swarm: mock store listings (#19157)

* swarm/storage/mock: implement listings methods for mem and rpc stores

* swarm/storage/mock/rpc: add comments and newTestStore helper function

* swarm/storage/mock/mem: add missing comments

* swarm/storage/mock: add comments to new types and constants

* swarm/storage/mock/db: implement listings for mock/db global store

* swarm/storage/mock/test: add comments for MockStoreListings

* swarm/storage/mock/explorer: initial implementation

* cmd/swarm/global-store: add chunk explorer

* cmd/swarm/global-store: add chunk explorer tests

* swarm/storage/mock/explorer: add tests

* swarm/storage/mock/explorer: add swagger api definition

* swarm/storage/mock/explorer: not-zero test values for invalid addr and key

* swarm/storage/mock/explorer: test wildcard cors origin

* swarm/storage/mock/db: renames based on Fabio's suggestions

* swarm/storage/mock/explorer: add more comments to testHandler function

* cmd/swarm/global-store: terminate subprocess with Kill in tests

cmd/swarm/global-store/explorer.go

@@ -0,0 +1,66 @@
+// Copyright 2019 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/http"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/swarm/storage/mock"
+	"github.com/ethereum/go-ethereum/swarm/storage/mock/explorer"
+	cli "gopkg.in/urfave/cli.v1"
+)
+
+// serveChunkExplorer starts an http server in background with chunk explorer handler
+// using the provided global store. Server is started if the returned shutdown function
+// is not nil.
+func serveChunkExplorer(ctx *cli.Context, globalStore mock.GlobalStorer) (shutdown func(), err error) {
+	if !ctx.IsSet("explorer-address") {
+		return nil, nil
+	}
+
+	corsOrigins := ctx.StringSlice("explorer-cors-origin")
+	server := &http.Server{
+		Handler:      explorer.NewHandler(globalStore, corsOrigins),
+		IdleTimeout:  30 * time.Minute,
+		ReadTimeout:  2 * time.Minute,
+		WriteTimeout: 2 * time.Minute,
+	}
+	listener, err := net.Listen("tcp", ctx.String("explorer-address"))
+	if err != nil {
+		return nil, fmt.Errorf("explorer: %v", err)
+	}
+	log.Info("chunk explorer http", "address", listener.Addr().String(), "origins", corsOrigins)
+
+	go func() {
+		if err := server.Serve(listener); err != nil {
+			log.Error("chunk explorer", "err", err)
+		}
+	}()
+
+	return func() {
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		if err := server.Shutdown(ctx); err != nil {
+			log.Error("chunk explorer: shutdown", "err", err)
+		}
+	}, nil
+}

cmd/swarm/global-store/explorer_test.go

@@ -0,0 +1,254 @@
+// Copyright 2019 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"sort"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/swarm/storage/mock/explorer"
+	mockRPC "github.com/ethereum/go-ethereum/swarm/storage/mock/rpc"
+)
+
+// TestExplorer validates basic chunk explorer functionality by storing
+// a small set of chunk and making http requests on exposed endpoint.
+// Full chunk explorer validation is done in mock/explorer package.
+func TestExplorer(t *testing.T) {
+	addr := findFreeTCPAddress(t)
+	explorerAddr := findFreeTCPAddress(t)
+	testCmd := runGlobalStore(t, "ws", "--addr", addr, "--explorer-address", explorerAddr)
+	defer testCmd.Kill()
+
+	client := websocketClient(t, addr)
+
+	store := mockRPC.NewGlobalStore(client)
+	defer store.Close()
+
+	nodeKeys := map[string][]string{
+		"a1": {"b1", "b2", "b3"},
+		"a2": {"b3", "b4", "b5"},
+	}
+
+	keyNodes := make(map[string][]string)
+
+	for addr, keys := range nodeKeys {
+		for _, key := range keys {
+			keyNodes[key] = append(keyNodes[key], addr)
+		}
+	}
+
+	invalidAddr := "c1"
+	invalidKey := "d1"
+
+	for addr, keys := range nodeKeys {
+		for _, key := range keys {
+			err := store.Put(common.HexToAddress(addr), common.Hex2Bytes(key), []byte("data"))
+			if err != nil {
+				t.Fatal(err)
+			}
+		}
+	}
+
+	endpoint := "http://" + explorerAddr
+
+	t.Run("has key", func(t *testing.T) {
+		for addr, keys := range nodeKeys {
+			for _, key := range keys {
+				testStatusResponse(t, endpoint+"/api/has-key/"+addr+"/"+key, http.StatusOK)
+				testStatusResponse(t, endpoint+"/api/has-key/"+invalidAddr+"/"+key, http.StatusNotFound)
+			}
+			testStatusResponse(t, endpoint+"/api/has-key/"+addr+"/"+invalidKey, http.StatusNotFound)
+		}
+		testStatusResponse(t, endpoint+"/api/has-key/"+invalidAddr+"/"+invalidKey, http.StatusNotFound)
+	})
+
+	t.Run("keys", func(t *testing.T) {
+		var keys []string
+		for key := range keyNodes {
+			keys = append(keys, key)
+		}
+		sort.Strings(keys)
+		testKeysResponse(t, endpoint+"/api/keys", explorer.KeysResponse{
+			Keys: keys,
+		})
+	})
+
+	t.Run("nodes", func(t *testing.T) {
+		var nodes []string
+		for addr := range nodeKeys {
+			nodes = append(nodes, common.HexToAddress(addr).Hex())
+		}
+		sort.Strings(nodes)
+		testNodesResponse(t, endpoint+"/api/nodes", explorer.NodesResponse{
+			Nodes: nodes,
+		})
+	})
+
+	t.Run("node keys", func(t *testing.T) {
+		for addr, keys := range nodeKeys {
+			testKeysResponse(t, endpoint+"/api/keys?node="+addr, explorer.KeysResponse{
+				Keys: keys,
+			})
+		}
+		testKeysResponse(t, endpoint+"/api/keys?node="+invalidAddr, explorer.KeysResponse{})
+	})
+
+	t.Run("key nodes", func(t *testing.T) {
+		for key, addrs := range keyNodes {
+			var nodes []string
+			for _, addr := range addrs {
+				nodes = append(nodes, common.HexToAddress(addr).Hex())
+			}
+			sort.Strings(nodes)
+			testNodesResponse(t, endpoint+"/api/nodes?key="+key, explorer.NodesResponse{
+				Nodes: nodes,
+			})
+		}
+		testNodesResponse(t, endpoint+"/api/nodes?key="+invalidKey, explorer.NodesResponse{})
+	})
+}
+
+// TestExplorer_CORSOrigin validates if chunk explorer returns
+// correct CORS origin header in GET and OPTIONS requests.
+func TestExplorer_CORSOrigin(t *testing.T) {
+	origin := "http://localhost/"
+	addr := findFreeTCPAddress(t)
+	explorerAddr := findFreeTCPAddress(t)
+	testCmd := runGlobalStore(t, "ws",
+		"--addr", addr,
+		"--explorer-address", explorerAddr,
+		"--explorer-cors-origin", origin,
+	)
+	defer testCmd.Kill()
+
+	// wait until the server is started
+	waitHTTPEndpoint(t, explorerAddr)
+
+	url := "http://" + explorerAddr + "/api/keys"
+
+	t.Run("get", func(t *testing.T) {
+		req, err := http.NewRequest(http.MethodGet, url, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		req.Header.Set("Origin", origin)
+
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatal(err)
+		}
+		header := resp.Header.Get("Access-Control-Allow-Origin")
+		if header != origin {
+			t.Errorf("got Access-Control-Allow-Origin header %q, want %q", header, origin)
+		}
+	})
+
+	t.Run("preflight", func(t *testing.T) {
+		req, err := http.NewRequest(http.MethodOptions, url, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		req.Header.Set("Origin", origin)
+		req.Header.Set("Access-Control-Request-Method", "GET")
+
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatal(err)
+		}
+		header := resp.Header.Get("Access-Control-Allow-Origin")
+		if header != origin {
+			t.Errorf("got Access-Control-Allow-Origin header %q, want %q", header, origin)
+		}
+	})
+}
+
+// testStatusResponse makes an http request to provided url
+// and validates if response is explorer.StatusResponse for
+// the expected status code.
+func testStatusResponse(t *testing.T, url string, code int) {
+	t.Helper()
+
+	resp, err := http.Get(url)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.StatusCode != code {
+		t.Errorf("got status code %v, want %v", resp.StatusCode, code)
+	}
+	var r explorer.StatusResponse
+	if err := json.NewDecoder(resp.Body).Decode(&r); err != nil {
+		t.Fatal(err)
+	}
+	if r.Code != code {
+		t.Errorf("got response code %v, want %v", r.Code, code)
+	}
+	if r.Message != http.StatusText(code) {
+		t.Errorf("got response message %q, want %q", r.Message, http.StatusText(code))
+	}
+}
+
+// testKeysResponse makes an http request to provided url
+// and validates if response machhes expected explorer.KeysResponse.
+func testKeysResponse(t *testing.T, url string, want explorer.KeysResponse) {
+	t.Helper()
+
+	resp, err := http.Get(url)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("got status code %v, want %v", resp.StatusCode, http.StatusOK)
+	}
+	var r explorer.KeysResponse
+	if err := json.NewDecoder(resp.Body).Decode(&r); err != nil {
+		t.Fatal(err)
+	}
+	if fmt.Sprint(r.Keys) != fmt.Sprint(want.Keys) {
+		t.Errorf("got keys %v, want %v", r.Keys, want.Keys)
+	}
+	if r.Next != want.Next {
+		t.Errorf("got next %s, want %s", r.Next, want.Next)
+	}
+}
+
+// testNodeResponse makes an http request to provided url
+// and validates if response machhes expected explorer.NodeResponse.
+func testNodesResponse(t *testing.T, url string, want explorer.NodesResponse) {
+	t.Helper()
+
+	resp, err := http.Get(url)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("got status code %v, want %v", resp.StatusCode, http.StatusOK)
+	}
+	var r explorer.NodesResponse
+	if err := json.NewDecoder(resp.Body).Decode(&r); err != nil {
+		t.Fatal(err)
+	}
+	if fmt.Sprint(r.Nodes) != fmt.Sprint(want.Nodes) {
+		t.Errorf("got nodes %v, want %v", r.Nodes, want.Nodes)
+	}
+	if r.Next != want.Next {
+		t.Errorf("got next %s, want %s", r.Next, want.Next)
+	}
+}

cmd/swarm/global-store/global_store.go

@@ -17,6 +17,7 @@
 package main
 
 import (
+	"io"
 	"net"
 	"net/http"
 	"os"
@@ -66,7 +67,7 @@ func startWS(ctx *cli.Context) (err error) {
 	return http.Serve(listener, server.WebsocketHandler(origins))
 }
 
-// newServer creates a global store and returns its RPC server.
+// newServer creates a global store and starts a chunk explorer server if configured.
 // Returned cleanup function should be called only if err is nil.
 func newServer(ctx *cli.Context) (server *rpc.Server, cleanup func(), err error) {
 	log.PrintOrigins(true)
@@ -81,7 +82,9 @@ func newServer(ctx *cli.Context) (server *rpc.Server, cleanup func(), err error)
 			return nil, nil, err
 		}
 		cleanup = func() {
-			dbStore.Close()
+			if err := dbStore.Close(); err != nil {
+				log.Error("global store: close", "err", err)
+			}
 		}
 		globalStore = dbStore
 		log.Info("database global store", "dir", dir)
@@ -96,5 +99,22 @@ func newServer(ctx *cli.Context) (server *rpc.Server, cleanup func(), err error)
 		return nil, nil, err
 	}
 
+	shutdown, err := serveChunkExplorer(ctx, globalStore)
+	if err != nil {
+		cleanup()
+		return nil, nil, err
+	}
+	if shutdown != nil {
+		cleanup = func() {
+			shutdown()
+
+			if c, ok := globalStore.(io.Closer); ok {
+				if err := c.Close(); err != nil {
+					log.Error("global store: close", "err", err)
+				}
+			}
+		}
+	}
+
 	return server, cleanup, nil
 }

cmd/swarm/global-store/global_store_test.go

@@ -69,16 +69,7 @@ func testHTTP(t *testing.T, put bool, args ...string) {
 
 	// wait until global store process is started as
 	// rpc.DialHTTP is actually not connecting
-	for i := 0; i < 1000; i++ {
-		_, err = http.DefaultClient.Get("http://" + addr)
-		if err == nil {
-			break
-		}
-		time.Sleep(10 * time.Millisecond)
-	}
-	if err != nil {
-		t.Fatal(err)
-	}
+	waitHTTPEndpoint(t, addr)
 
 	store := mockRPC.NewGlobalStore(client)
 	defer store.Close()
@@ -137,19 +128,7 @@ func testWebsocket(t *testing.T, put bool, args ...string) {
 	testCmd := runGlobalStore(t, append([]string{"ws", "--addr", addr}, args...)...)
 	defer testCmd.Kill()
 
-	var client *rpc.Client
-	var err error
-	// wait until global store process is started
-	for i := 0; i < 1000; i++ {
-		client, err = rpc.DialWebsocket(context.Background(), "ws://"+addr, "")
-		if err == nil {
-			break
-		}
-		time.Sleep(10 * time.Millisecond)
-	}
-	if err != nil {
-		t.Fatal(err)
-	}
+	client := websocketClient(t, addr)
 
 	store := mockRPC.NewGlobalStore(client)
 	defer store.Close()
@@ -160,7 +139,7 @@ func testWebsocket(t *testing.T, put bool, args ...string) {
 	wantValue := "value"
 
 	if put {
-		err = node.Put([]byte(wantKey), []byte(wantValue))
+		err := node.Put([]byte(wantKey), []byte(wantValue))
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -189,3 +168,40 @@ func findFreeTCPAddress(t *testing.T) (addr string) {
 
 	return listener.Addr().String()
 }
+
+// websocketClient waits until global store process is started
+// and returns rpc client.
+func websocketClient(t *testing.T, addr string) (client *rpc.Client) {
+	t.Helper()
+
+	var err error
+	for i := 0; i < 1000; i++ {
+		client, err = rpc.DialWebsocket(context.Background(), "ws://"+addr, "")
+		if err == nil {
+			break
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	return client
+}
+
+// waitHTTPEndpoint retries http requests to a provided
+// address until the connection is established.
+func waitHTTPEndpoint(t *testing.T, addr string) {
+	t.Helper()
+
+	var err error
+	for i := 0; i < 1000; i++ {
+		_, err = http.Get("http://" + addr)
+		if err == nil {
+			break
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+}

cmd/swarm/global-store/main.go

@@ -19,12 +19,14 @@ package main
 import (
 	"os"
 
-	"github.com/ethereum/go-ethereum/cmd/utils"
 	"github.com/ethereum/go-ethereum/log"
 	cli "gopkg.in/urfave/cli.v1"
 )
 
-var gitCommit string // Git SHA1 commit hash of the release (set via linker flags)
+var (
+	version   = "0.1"
+	gitCommit string // Git SHA1 commit hash of the release (set via linker flags)
+)
 
 func main() {
 	err := newApp().Run(os.Args)
@@ -37,16 +39,30 @@ func main() {
 // newApp construct a new instance of Swarm Global Store.
 // Method Run is called on it in the main function and in tests.
 func newApp() (app *cli.App) {
-	app = utils.NewApp(gitCommit, "Swarm Global Store")
-
+	app = cli.NewApp()
 	app.Name = "global-store"
+	app.Version = version
+	if len(gitCommit) >= 8 {
+		app.Version += "-" + gitCommit[:8]
+	}
+	app.Usage = "Swarm Global Store"
 
 	// app flags (for all commands)
 	app.Flags = []cli.Flag{
 		cli.IntFlag{
 			Name:  "verbosity",
 			Value: 3,
-			Usage: "verbosity level",
+			Usage: "Verbosity level.",
+		},
+		cli.StringFlag{
+			Name:  "explorer-address",
+			Value: "",
+			Usage: "Chunk explorer HTTP listener address.",
+		},
+		cli.StringSliceFlag{
+			Name:  "explorer-cors-origin",
+			Value: nil,
+			Usage: "Chunk explorer CORS origin (can be specified multiple times).",
 		},
 	}
 
@@ -54,7 +70,7 @@ func newApp() (app *cli.App) {
 		{
 			Name:    "http",
 			Aliases: []string{"h"},
-			Usage:   "start swarm global store with http server",
+			Usage:   "Start swarm global store with HTTP server.",
 			Action:  startHTTP,
 			// Flags only for "start" command.
 			// Allow app flags to be specified after the
@@ -63,19 +79,19 @@ func newApp() (app *cli.App) {
 				cli.StringFlag{
 					Name:  "dir",
 					Value: "",
-					Usage: "data directory",
+					Usage: "Data directory.",
 				},
 				cli.StringFlag{
 					Name:  "addr",
 					Value: "0.0.0.0:3033",
-					Usage: "address to listen for http connection",
+					Usage: "Address to listen for HTTP connections.",
 				},
 			),
 		},
 		{
 			Name:    "websocket",
 			Aliases: []string{"ws"},
-			Usage:   "start swarm global store with websocket server",
+			Usage:   "Start swarm global store with WebSocket server.",
 			Action:  startWS,
 			// Flags only for "start" command.
 			// Allow app flags to be specified after the
@@ -84,17 +100,17 @@ func newApp() (app *cli.App) {
 				cli.StringFlag{
 					Name:  "dir",
 					Value: "",
-					Usage: "data directory",
+					Usage: "Data directory.",
 				},
 				cli.StringFlag{
 					Name:  "addr",
 					Value: "0.0.0.0:3033",
-					Usage: "address to listen for websocket connection",
+					Usage: "Address to listen for WebSocket connections.",
 				},
 				cli.StringSliceFlag{
-					Name:  "origins",
-					Value: &cli.StringSlice{"*"},
-					Usage: "websocket origins",
+					Name:  "origin",
+					Value: nil,
+					Usage: "WebSocket CORS origin (can be specified multiple times).",
 				},
 			),
 		},

swarm/storage/mock/db/db.go

@@ -21,8 +21,12 @@ import (
 	"archive/tar"
 	"bytes"
 	"encoding/json"
+	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
+	"sync"
+	"time"
 
 	"github.com/syndtr/goleveldb/leveldb"
 	"github.com/syndtr/goleveldb/leveldb/util"
@@ -37,6 +41,10 @@ import (
 // release resources used by the database.
 type GlobalStore struct {
 	db *leveldb.DB
+	// protects nodes and keys indexes
+	// in Put and Delete methods
+	nodesLocks sync.Map
+	keysLocks  sync.Map
 }
 
 // NewGlobalStore creates a new instance of GlobalStore.
@@ -64,14 +72,14 @@ func (s *GlobalStore) NewNodeStore(addr common.Address) *mock.NodeStore {
 // Get returns chunk data if the chunk with key exists for node
 // on address addr.
 func (s *GlobalStore) Get(addr common.Address, key []byte) (data []byte, err error) {
-	has, err := s.db.Has(nodeDBKey(addr, key), nil)
+	has, err := s.db.Has(indexForHashesPerNode(addr, key), nil)
 	if err != nil {
 		return nil, mock.ErrNotFound
 	}
 	if !has {
 		return nil, mock.ErrNotFound
 	}
-	data, err = s.db.Get(dataDBKey(key), nil)
+	data, err = s.db.Get(indexDataKey(key), nil)
 	if err == leveldb.ErrNotFound {
 		err = mock.ErrNotFound
 	}
@@ -80,28 +88,165 @@ func (s *GlobalStore) Get(addr common.Address, key []byte) (data []byte, err err
 
 // Put saves the chunk data for node with address addr.
 func (s *GlobalStore) Put(addr common.Address, key []byte, data []byte) error {
+	unlock, err := s.lock(addr, key)
+	if err != nil {
+		return err
+	}
+	defer unlock()
+
 	batch := new(leveldb.Batch)
-	batch.Put(nodeDBKey(addr, key), nil)
-	batch.Put(dataDBKey(key), data)
+	batch.Put(indexForHashesPerNode(addr, key), nil)
+	batch.Put(indexForNodesWithHash(key, addr), nil)
+	batch.Put(indexForNodes(addr), nil)
+	batch.Put(indexForHashes(key), nil)
+	batch.Put(indexDataKey(key), data)
 	return s.db.Write(batch, nil)
 }
 
 // Delete removes the chunk reference to node with address addr.
 func (s *GlobalStore) Delete(addr common.Address, key []byte) error {
+	unlock, err := s.lock(addr, key)
+	if err != nil {
+		return err
+	}
+	defer unlock()
+
 	batch := new(leveldb.Batch)
-	batch.Delete(nodeDBKey(addr, key))
+	batch.Delete(indexForHashesPerNode(addr, key))
+	batch.Delete(indexForNodesWithHash(key, addr))
+
+	// check if this node contains any keys, and if not
+	// remove it from the
+	x := indexForHashesPerNodePrefix(addr)
+	if k, _ := s.db.Get(x, nil); !bytes.HasPrefix(k, x) {
+		batch.Delete(indexForNodes(addr))
+	}
+
+	x = indexForNodesWithHashPrefix(key)
+	if k, _ := s.db.Get(x, nil); !bytes.HasPrefix(k, x) {
+		batch.Delete(indexForHashes(key))
+	}
 	return s.db.Write(batch, nil)
 }
 
 // HasKey returns whether a node with addr contains the key.
 func (s *GlobalStore) HasKey(addr common.Address, key []byte) bool {
-	has, err := s.db.Has(nodeDBKey(addr, key), nil)
+	has, err := s.db.Has(indexForHashesPerNode(addr, key), nil)
 	if err != nil {
 		has = false
 	}
 	return has
 }
 
+// Keys returns a paginated list of keys on all nodes.
+func (s *GlobalStore) Keys(startKey []byte, limit int) (keys mock.Keys, err error) {
+	return s.keys(nil, startKey, limit)
+}
+
+// Nodes returns a paginated list of all known nodes.
+func (s *GlobalStore) Nodes(startAddr *common.Address, limit int) (nodes mock.Nodes, err error) {
+	return s.nodes(nil, startAddr, limit)
+}
+
+// NodeKeys returns a paginated list of keys on a node with provided address.
+func (s *GlobalStore) NodeKeys(addr common.Address, startKey []byte, limit int) (keys mock.Keys, err error) {
+	return s.keys(&addr, startKey, limit)
+}
+
+// KeyNodes returns a paginated list of nodes that contain a particular key.
+func (s *GlobalStore) KeyNodes(key []byte, startAddr *common.Address, limit int) (nodes mock.Nodes, err error) {
+	return s.nodes(key, startAddr, limit)
+}
+
+// keys returns a paginated list of keys. If addr is not nil, only keys on that
+// node will be returned.
+func (s *GlobalStore) keys(addr *common.Address, startKey []byte, limit int) (keys mock.Keys, err error) {
+	iter := s.db.NewIterator(nil, nil)
+	defer iter.Release()
+
+	if limit <= 0 {
+		limit = mock.DefaultLimit
+	}
+
+	prefix := []byte{indexForHashesPrefix}
+	if addr != nil {
+		prefix = indexForHashesPerNodePrefix(*addr)
+	}
+	if startKey != nil {
+		if addr != nil {
+			startKey = indexForHashesPerNode(*addr, startKey)
+		} else {
+			startKey = indexForHashes(startKey)
+		}
+	} else {
+		startKey = prefix
+	}
+
+	ok := iter.Seek(startKey)
+	if !ok {
+		return keys, iter.Error()
+	}
+	for ; ok; ok = iter.Next() {
+		k := iter.Key()
+		if !bytes.HasPrefix(k, prefix) {
+			break
+		}
+		key := append([]byte(nil), bytes.TrimPrefix(k, prefix)...)
+
+		if len(keys.Keys) >= limit {
+			keys.Next = key
+			break
+		}
+
+		keys.Keys = append(keys.Keys, key)
+	}
+	return keys, iter.Error()
+}
+
+// nodes returns a paginated list of node addresses. If key is not nil,
+// only nodes that contain that key will be returned.
+func (s *GlobalStore) nodes(key []byte, startAddr *common.Address, limit int) (nodes mock.Nodes, err error) {
+	iter := s.db.NewIterator(nil, nil)
+	defer iter.Release()
+
+	if limit <= 0 {
+		limit = mock.DefaultLimit
+	}
+
+	prefix := []byte{indexForNodesPrefix}
+	if key != nil {
+		prefix = indexForNodesWithHashPrefix(key)
+	}
+	startKey := prefix
+	if startAddr != nil {
+		if key != nil {
+			startKey = indexForNodesWithHash(key, *startAddr)
+		} else {
+			startKey = indexForNodes(*startAddr)
+		}
+	}
+
+	ok := iter.Seek(startKey)
+	if !ok {
+		return nodes, iter.Error()
+	}
+	for ; ok; ok = iter.Next() {
+		k := iter.Key()
+		if !bytes.HasPrefix(k, prefix) {
+			break
+		}
+		addr := common.BytesToAddress(append([]byte(nil), bytes.TrimPrefix(k, prefix)...))
+
+		if len(nodes.Addrs) >= limit {
+			nodes.Next = &addr
+			break
+		}
+
+		nodes.Addrs = append(nodes.Addrs, addr)
+	}
+	return nodes, iter.Error()
+}
+
 // Import reads tar archive from a reader that contains exported chunk data.
 // It returns the number of chunks imported and an error.
 func (s *GlobalStore) Import(r io.Reader) (n int, err error) {
@@ -126,12 +271,18 @@ func (s *GlobalStore) Import(r io.Reader) (n int, err error) {
 			return n, err
 		}
 
+		key := common.Hex2Bytes(hdr.Name)
+
 		batch := new(leveldb.Batch)
 		for _, addr := range c.Addrs {
-			batch.Put(nodeDBKeyHex(addr, hdr.Name), nil)
+			batch.Put(indexForHashesPerNode(addr, key), nil)
+			batch.Put(indexForNodesWithHash(key, addr), nil)
+			batch.Put(indexForNodes(addr), nil)
 		}
 
-		batch.Put(dataDBKey(common.Hex2Bytes(hdr.Name)), c.Data)
+		batch.Put(indexForHashes(key), nil)
+		batch.Put(indexDataKey(key), c.Data)
+
 		if err = s.db.Write(batch, nil); err != nil {
 			return n, err
 		}
@@ -150,18 +301,23 @@ func (s *GlobalStore) Export(w io.Writer) (n int, err error) {
 	buf := bytes.NewBuffer(make([]byte, 0, 1024))
 	encoder := json.NewEncoder(buf)
 
-	iter := s.db.NewIterator(util.BytesPrefix(nodeKeyPrefix), nil)
+	snap, err := s.db.GetSnapshot()
+	if err != nil {
+		return 0, err
+	}
+
+	iter := snap.NewIterator(util.BytesPrefix([]byte{indexForHashesByNodePrefix}), nil)
 	defer iter.Release()
 
 	var currentKey string
 	var addrs []common.Address
 
-	saveChunk := func(hexKey string) error {
-		key := common.Hex2Bytes(hexKey)
+	saveChunk := func() error {
+		hexKey := currentKey
 
-		data, err := s.db.Get(dataDBKey(key), nil)
+		data, err := snap.Get(indexDataKey(common.Hex2Bytes(hexKey)), nil)
 		if err != nil {
-			return err
+			return fmt.Errorf("get data %s: %v", hexKey, err)
 		}
 
 		buf.Reset()
@@ -189,8 +345,8 @@ func (s *GlobalStore) Export(w io.Writer) (n int, err error) {
 	}
 
 	for iter.Next() {
-		k := bytes.TrimPrefix(iter.Key(), nodeKeyPrefix)
-		i := bytes.Index(k, []byte("-"))
+		k := bytes.TrimPrefix(iter.Key(), []byte{indexForHashesByNodePrefix})
+		i := bytes.Index(k, []byte{keyTermByte})
 		if i < 0 {
 			continue
 		}
@@ -201,7 +357,7 @@ func (s *GlobalStore) Export(w io.Writer) (n int, err error) {
 		}
 
 		if hexKey != currentKey {
-			if err = saveChunk(currentKey); err != nil {
+			if err = saveChunk(); err != nil {
 				return n, err
 			}
 
@@ -209,35 +365,112 @@ func (s *GlobalStore) Export(w io.Writer) (n int, err error) {
 		}
 
 		currentKey = hexKey
-		addrs = append(addrs, common.BytesToAddress(k[i:]))
+		addrs = append(addrs, common.BytesToAddress(k[i+1:]))
 	}
 
 	if len(addrs) > 0 {
-		if err = saveChunk(currentKey); err != nil {
+		if err = saveChunk(); err != nil {
 			return n, err
 		}
 	}
 
-	return n, err
+	return n, iter.Error()
 }
 
 var (
-	nodeKeyPrefix = []byte("node-")
-	dataKeyPrefix = []byte("data-")
+	// maximal time for lock to wait until it returns error
+	lockTimeout = 3 * time.Second
+	// duration between two lock checks.
+	lockCheckDelay = 30 * time.Microsecond
+	// error returned by lock method when lock timeout is reached
+	errLockTimeout = errors.New("lock timeout")
+)
+
+// lock protects parallel writes in Put and Delete methods for both
+// node with provided address and for data with provided key.
+func (s *GlobalStore) lock(addr common.Address, key []byte) (unlock func(), err error) {
+	start := time.Now()
+	nodeLockKey := addr.Hex()
+	for {
+		_, loaded := s.nodesLocks.LoadOrStore(nodeLockKey, struct{}{})
+		if !loaded {
+			break
+		}
+		time.Sleep(lockCheckDelay)
+		if time.Since(start) > lockTimeout {
+			return nil, errLockTimeout
+		}
+	}
+	start = time.Now()
+	keyLockKey := common.Bytes2Hex(key)
+	for {
+		_, loaded := s.keysLocks.LoadOrStore(keyLockKey, struct{}{})
+		if !loaded {
+			break
+		}
+		time.Sleep(lockCheckDelay)
+		if time.Since(start) > lockTimeout {
+			return nil, errLockTimeout
+		}
+	}
+	return func() {
+		s.nodesLocks.Delete(nodeLockKey)
+		s.keysLocks.Delete(keyLockKey)
+	}, nil
+}
+
+const (
+	// prefixes for different indexes
+	indexDataPrefix               = 0
+	indexForNodesWithHashesPrefix = 1
+	indexForHashesByNodePrefix    = 2
+	indexForNodesPrefix           = 3
+	indexForHashesPrefix          = 4
+
+	// keyTermByte splits keys and node addresses
+	// in database keys
+	keyTermByte = 0xff
 )
 
-// nodeDBKey constructs a database key for key/node mappings.
-func nodeDBKey(addr common.Address, key []byte) []byte {
-	return nodeDBKeyHex(addr, common.Bytes2Hex(key))
+// indexForHashesPerNode constructs a database key to store keys used in
+// NodeKeys method.
+func indexForHashesPerNode(addr common.Address, key []byte) []byte {
+	return append(indexForHashesPerNodePrefix(addr), key...)
+}
+
+// indexForHashesPerNodePrefix returns a prefix containing a node address used in
+// NodeKeys method. Node address is hex encoded to be able to use keyTermByte
+// for splitting node address and key.
+func indexForHashesPerNodePrefix(addr common.Address) []byte {
+	return append([]byte{indexForNodesWithHashesPrefix}, append([]byte(addr.Hex()), keyTermByte)...)
+}
+
+// indexForNodesWithHash constructs a database key to store keys used in
+// KeyNodes method.
+func indexForNodesWithHash(key []byte, addr common.Address) []byte {
+	return append(indexForNodesWithHashPrefix(key), addr[:]...)
+}
+
+// indexForNodesWithHashPrefix returns a prefix containing a key used in
+// KeyNodes method. Key is hex encoded to be able to use keyTermByte
+// for splitting key and node address.
+func indexForNodesWithHashPrefix(key []byte) []byte {
+	return append([]byte{indexForHashesByNodePrefix}, append([]byte(common.Bytes2Hex(key)), keyTermByte)...)
+}
+
+// indexForNodes constructs a database key to store keys used in
+// Nodes method.
+func indexForNodes(addr common.Address) []byte {
+	return append([]byte{indexForNodesPrefix}, addr[:]...)
 }
 
-// nodeDBKeyHex constructs a database key for key/node mappings
-// using the hexadecimal string representation of the key.
-func nodeDBKeyHex(addr common.Address, hexKey string) []byte {
-	return append(append(nodeKeyPrefix, []byte(hexKey+"-")...), addr[:]...)
+// indexForHashes constructs a database key to store keys used in
+// Keys method.
+func indexForHashes(key []byte) []byte {
+	return append([]byte{indexForHashesPrefix}, key...)
 }
 
-// dataDBkey constructs a database key for key/data storage.
-func dataDBKey(key []byte) []byte {
-	return append(dataKeyPrefix, key...)
+// indexDataKey constructs a database key for key/data storage.
+func indexDataKey(key []byte) []byte {
+	return append([]byte{indexDataPrefix}, key...)
 }

swarm/storage/mock/db/db_test.go

@@ -1,5 +1,3 @@
-// +build go1.8
-//
 // Copyright 2018 The go-ethereum Authors
 // This file is part of the go-ethereum library.
 //
@@ -29,47 +27,49 @@ import (
 // TestDBStore is running a test.MockStore tests
 // using test.MockStore function.
 func TestDBStore(t *testing.T) {
-	dir, err := ioutil.TempDir("", "mock_"+t.Name())
-	if err != nil {
-		panic(err)
-	}
-	defer os.RemoveAll(dir)
-
-	store, err := NewGlobalStore(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer store.Close()
+	store, cleanup := newTestStore(t)
+	defer cleanup()
 
 	test.MockStore(t, store, 100)
 }
 
+// TestDBStoreListings is running test.MockStoreListings tests.
+func TestDBStoreListings(t *testing.T) {
+	store, cleanup := newTestStore(t)
+	defer cleanup()
+
+	test.MockStoreListings(t, store, 1000)
+}
+
 // TestImportExport is running a test.ImportExport tests
 // using test.MockStore function.
 func TestImportExport(t *testing.T) {
-	dir1, err := ioutil.TempDir("", "mock_"+t.Name()+"_exporter")
-	if err != nil {
-		panic(err)
-	}
-	defer os.RemoveAll(dir1)
+	store1, cleanup := newTestStore(t)
+	defer cleanup()
 
-	store1, err := NewGlobalStore(dir1)
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer store1.Close()
+	store2, cleanup := newTestStore(t)
+	defer cleanup()
+
+	test.ImportExport(t, store1, store2, 100)
+}
 
-	dir2, err := ioutil.TempDir("", "mock_"+t.Name()+"_importer")
+// newTestStore creates a temporary GlobalStore
+// that will be closed and data deleted when
+// calling returned cleanup function.
+func newTestStore(t *testing.T) (s *GlobalStore, cleanup func()) {
+	dir, err := ioutil.TempDir("", "swarm-mock-db-")
 	if err != nil {
-		panic(err)
+		t.Fatal(err)
 	}
-	defer os.RemoveAll(dir2)
 
-	store2, err := NewGlobalStore(dir2)
+	s, err = NewGlobalStore(dir)
 	if err != nil {
+		os.RemoveAll(dir)
 		t.Fatal(err)
 	}
-	defer store2.Close()
 
-	test.ImportExport(t, store1, store2, 100)
+	return s, func() {
+		s.Close()
+		os.RemoveAll(dir)
+	}
 }

swarm/storage/mock/explorer/explorer.go

@@ -0,0 +1,257 @@
+// Copyright 2019 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package explorer
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/swarm/log"
+	"github.com/ethereum/go-ethereum/swarm/storage/mock"
+	"github.com/rs/cors"
+)
+
+const jsonContentType = "application/json; charset=utf-8"
+
+// NewHandler constructs an http.Handler with router
+// that servers requests required by chunk explorer.
+//
+//   /api/has-key/{node}/{key}
+//   /api/keys?start={key}&node={node}&limit={int[0..1000]}
+//   /api/nodes?start={node}&key={key}&limit={int[0..1000]}
+//
+// Data from global store will be served and appropriate
+// CORS headers will be sent if allowed origins are provided.
+func NewHandler(store mock.GlobalStorer, corsOrigins []string) (handler http.Handler) {
+	mux := http.NewServeMux()
+	mux.Handle("/api/has-key/", newHasKeyHandler(store))
+	mux.Handle("/api/keys", newKeysHandler(store))
+	mux.Handle("/api/nodes", newNodesHandler(store))
+	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		jsonStatusResponse(w, http.StatusNotFound)
+	})
+	handler = noCacheHandler(mux)
+	if corsOrigins != nil {
+		handler = cors.New(cors.Options{
+			AllowedOrigins: corsOrigins,
+			AllowedMethods: []string{"GET"},
+			MaxAge:         600,
+		}).Handler(handler)
+	}
+	return handler
+}
+
+// newHasKeyHandler returns a new handler that serves
+// requests for HasKey global store method.
+// Possible responses are StatusResponse with
+// status codes 200 or 404 if the chunk is found or not.
+func newHasKeyHandler(store mock.GlobalStorer) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		addr, key, ok := parseHasKeyPath(r.URL.Path)
+		if !ok {
+			jsonStatusResponse(w, http.StatusNotFound)
+			return
+		}
+		found := store.HasKey(addr, key)
+		if !found {
+			jsonStatusResponse(w, http.StatusNotFound)
+			return
+		}
+		jsonStatusResponse(w, http.StatusOK)
+	}
+}
+
+// KeysResponse is a JSON-encoded response for global store
+// Keys and NodeKeys methods.
+type KeysResponse struct {
+	Keys []string `json:"keys"`
+	Next string   `json:"next,omitempty"`
+}
+
+// newKeysHandler returns a new handler that serves
+// requests for Key global store method.
+// HTTP response body will be JSON-encoded KeysResponse.
+func newKeysHandler(store mock.GlobalStorer) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		q := r.URL.Query()
+		node := q.Get("node")
+		start, limit := listingPage(q)
+
+		var keys mock.Keys
+		if node == "" {
+			var err error
+			keys, err = store.Keys(common.Hex2Bytes(start), limit)
+			if err != nil {
+				log.Error("chunk explorer: keys handler: get keys", "start", start, "err", err)
+				jsonStatusResponse(w, http.StatusInternalServerError)
+				return
+			}
+		} else {
+			var err error
+			keys, err = store.NodeKeys(common.HexToAddress(node), common.Hex2Bytes(start), limit)
+			if err != nil {
+				log.Error("chunk explorer: keys handler: get node keys", "node", node, "start", start, "err", err)
+				jsonStatusResponse(w, http.StatusInternalServerError)
+				return
+			}
+		}
+		ks := make([]string, len(keys.Keys))
+		for i, k := range keys.Keys {
+			ks[i] = common.Bytes2Hex(k)
+		}
+		data, err := json.Marshal(KeysResponse{
+			Keys: ks,
+			Next: common.Bytes2Hex(keys.Next),
+		})
+		if err != nil {
+			log.Error("chunk explorer: keys handler: json marshal", "err", err)
+			jsonStatusResponse(w, http.StatusInternalServerError)
+			return
+		}
+		w.Header().Set("Content-Type", jsonContentType)
+		_, err = io.Copy(w, bytes.NewReader(data))
+		if err != nil {
+			log.Error("chunk explorer: keys handler: write response", "err", err)
+		}
+	}
+}
+
+// NodesResponse is a JSON-encoded response for global store
+// Nodes and KeyNodes methods.
+type NodesResponse struct {
+	Nodes []string `json:"nodes"`
+	Next  string   `json:"next,omitempty"`
+}
+
+// newNodesHandler returns a new handler that serves
+// requests for Nodes global store method.
+// HTTP response body will be JSON-encoded NodesResponse.
+func newNodesHandler(store mock.GlobalStorer) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		q := r.URL.Query()
+		key := q.Get("key")
+		var start *common.Address
+		queryStart, limit := listingPage(q)
+		if queryStart != "" {
+			s := common.HexToAddress(queryStart)
+			start = &s
+		}
+
+		var nodes mock.Nodes
+		if key == "" {
+			var err error
+			nodes, err = store.Nodes(start, limit)
+			if err != nil {
+				log.Error("chunk explorer: nodes handler: get nodes", "start", queryStart, "err", err)
+				jsonStatusResponse(w, http.StatusInternalServerError)
+				return
+			}
+		} else {
+			var err error
+			nodes, err = store.KeyNodes(common.Hex2Bytes(key), start, limit)
+			if err != nil {
+				log.Error("chunk explorer: nodes handler: get key nodes", "key", key, "start", queryStart, "err", err)
+				jsonStatusResponse(w, http.StatusInternalServerError)
+				return
+			}
+		}
+		ns := make([]string, len(nodes.Addrs))
+		for i, n := range nodes.Addrs {
+			ns[i] = n.Hex()
+		}
+		var next string
+		if nodes.Next != nil {
+			next = nodes.Next.Hex()
+		}
+		data, err := json.Marshal(NodesResponse{
+			Nodes: ns,
+			Next:  next,
+		})
+		if err != nil {
+			log.Error("chunk explorer: nodes handler", "err", err)
+			jsonStatusResponse(w, http.StatusInternalServerError)
+			return
+		}
+		w.Header().Set("Content-Type", jsonContentType)
+		_, err = io.Copy(w, bytes.NewReader(data))
+		if err != nil {
+			log.Error("chunk explorer: nodes handler: write response", "err", err)
+		}
+	}
+}
+
+// parseHasKeyPath extracts address and key from HTTP request
+// path for HasKey route: /api/has-key/{node}/{key}.
+// If ok is false, the provided path is not matched.
+func parseHasKeyPath(p string) (addr common.Address, key []byte, ok bool) {
+	p = strings.TrimPrefix(p, "/api/has-key/")
+	parts := strings.SplitN(p, "/", 2)
+	if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
+		return addr, nil, false
+	}
+	addr = common.HexToAddress(parts[0])
+	key = common.Hex2Bytes(parts[1])
+	return addr, key, true
+}
+
+// listingPage returns start value and listing limit
+// from url query values.
+func listingPage(q url.Values) (start string, limit int) {
+	// if limit is not a valid integer (or blank string),
+	// ignore the error and use the returned 0 value
+	limit, _ = strconv.Atoi(q.Get("limit"))
+	return q.Get("start"), limit
+}
+
+// StatusResponse is a standardized JSON-encoded response
+// that contains information about HTTP response code
+// for easier status identification.
+type StatusResponse struct {
+	Message string `json:"message"`
+	Code    int    `json:"code"`
+}
+
+// jsonStatusResponse writes to the response writer
+// JSON-encoded StatusResponse based on the provided status code.
+func jsonStatusResponse(w http.ResponseWriter, code int) {
+	w.Header().Set("Content-Type", jsonContentType)
+	w.WriteHeader(code)
+	err := json.NewEncoder(w).Encode(StatusResponse{
+		Message: http.StatusText(code),
+		Code:    code,
+	})
+	if err != nil {
+		log.Error("chunk explorer: json status response", "err", err)
+	}
+}
+
+// noCacheHandler sets required HTTP headers to prevent
+// response caching at the client side.
+func noCacheHandler(h http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Cache-Control", "no-cache, no-store, must-revalidate")
+		w.Header().Set("Pragma", "no-cache")
+		w.Header().Set("Expires", "0")
+		h.ServeHTTP(w, r)
+	})
+}

swarm/storage/mock/explorer/explorer_test.go

@@ -0,0 +1,471 @@
+// Copyright 2019 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package explorer
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/swarm/storage/mock"
+	"github.com/ethereum/go-ethereum/swarm/storage/mock/db"
+	"github.com/ethereum/go-ethereum/swarm/storage/mock/mem"
+)
+
+// TestHandler_memGlobalStore runs a set of tests
+// to validate handler with mem global store.
+func TestHandler_memGlobalStore(t *testing.T) {
+	t.Parallel()
+
+	globalStore := mem.NewGlobalStore()
+
+	testHandler(t, globalStore)
+}
+
+// TestHandler_dbGlobalStore runs a set of tests
+// to validate handler with database global store.
+func TestHandler_dbGlobalStore(t *testing.T) {
+	t.Parallel()
+
+	dir, err := ioutil.TempDir("", "swarm-mock-explorer-db-")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	globalStore, err := db.NewGlobalStore(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer globalStore.Close()
+
+	testHandler(t, globalStore)
+}
+
+// testHandler stores data distributed by node addresses
+// and validates if this data is correctly retrievable
+// by using the http.Handler returned by NewHandler function.
+// This test covers all HTTP routes and various get parameters
+// on them to check paginated results.
+func testHandler(t *testing.T, globalStore mock.GlobalStorer) {
+	const (
+		nodeCount       = 350
+		keyCount        = 250
+		keysOnNodeCount = 150
+	)
+
+	// keys for every node
+	nodeKeys := make(map[string][]string)
+
+	// a node address that is not present in global store
+	invalidAddr := "0x7b8b72938c254cf002c4e1e714d27e022be88d93"
+
+	// a key that is not present in global store
+	invalidKey := "f9824192fb515cfb"
+
+	for i := 1; i <= nodeCount; i++ {
+		b := make([]byte, 8)
+		binary.BigEndian.PutUint64(b, uint64(i))
+		addr := common.BytesToAddress(b).Hex()
+		nodeKeys[addr] = make([]string, 0)
+	}
+
+	for i := 1; i <= keyCount; i++ {
+		b := make([]byte, 8)
+		binary.BigEndian.PutUint64(b, uint64(i))
+
+		key := common.Bytes2Hex(b)
+
+		var c int
+		for addr := range nodeKeys {
+			nodeKeys[addr] = append(nodeKeys[addr], key)
+			c++
+			if c >= keysOnNodeCount {
+				break
+			}
+		}
+	}
+
+	// sort keys for every node as they are expected to be
+	// sorted in HTTP responses
+	for _, keys := range nodeKeys {
+		sort.Strings(keys)
+	}
+
+	// nodes for every key
+	keyNodes := make(map[string][]string)
+
+	// construct a reverse mapping of nodes for every key
+	for addr, keys := range nodeKeys {
+		for _, key := range keys {
+			keyNodes[key] = append(keyNodes[key], addr)
+		}
+	}
+
+	// sort node addresses with case insensitive sort,
+	// as hex letters in node addresses are in mixed caps
+	for _, addrs := range keyNodes {
+		sortCaseInsensitive(addrs)
+	}
+
+	// find a key that is not stored at the address
+	var (
+		unmatchedAddr string
+		unmatchedKey  string
+	)
+	for addr, keys := range nodeKeys {
+		for key := range keyNodes {
+			var found bool
+			for _, k := range keys {
+				if k == key {
+					found = true
+					break
+				}
+			}
+			if !found {
+				unmatchedAddr = addr
+				unmatchedKey = key
+			}
+			break
+		}
+		if unmatchedAddr != "" {
+			break
+		}
+	}
+	// check if unmatched key/address pair is found
+	if unmatchedAddr == "" || unmatchedKey == "" {
+		t.Fatalf("could not find a key that is not associated with a node")
+	}
+
+	// store the data
+	for addr, keys := range nodeKeys {
+		for _, key := range keys {
+			err := globalStore.Put(common.HexToAddress(addr), common.Hex2Bytes(key), []byte("data"))
+			if err != nil {
+				t.Fatal(err)
+			}
+		}
+	}
+
+	handler := NewHandler(globalStore, nil)
+
+	// this subtest confirms that it has uploaded key and that it does not have invalid keys
+	t.Run("has key", func(t *testing.T) {
+		for addr, keys := range nodeKeys {
+			for _, key := range keys {
+				testStatusResponse(t, handler, "/api/has-key/"+addr+"/"+key, http.StatusOK)
+				testStatusResponse(t, handler, "/api/has-key/"+invalidAddr+"/"+key, http.StatusNotFound)
+			}
+			testStatusResponse(t, handler, "/api/has-key/"+addr+"/"+invalidKey, http.StatusNotFound)
+		}
+		testStatusResponse(t, handler, "/api/has-key/"+invalidAddr+"/"+invalidKey, http.StatusNotFound)
+		testStatusResponse(t, handler, "/api/has-key/"+unmatchedAddr+"/"+unmatchedKey, http.StatusNotFound)
+	})
+
+	// this subtest confirms that all keys are are listed in correct order with expected pagination
+	t.Run("keys", func(t *testing.T) {
+		var allKeys []string
+		for key := range keyNodes {
+			allKeys = append(allKeys, key)
+		}
+		sort.Strings(allKeys)
+
+		t.Run("limit 0", testKeys(handler, allKeys, 0, ""))
+		t.Run("limit default", testKeys(handler, allKeys, mock.DefaultLimit, ""))
+		t.Run("limit 2x default", testKeys(handler, allKeys, 2*mock.DefaultLimit, ""))
+		t.Run("limit 0.5x default", testKeys(handler, allKeys, mock.DefaultLimit/2, ""))
+		t.Run("limit max", testKeys(handler, allKeys, mock.MaxLimit, ""))
+		t.Run("limit 2x max", testKeys(handler, allKeys, 2*mock.MaxLimit, ""))
+		t.Run("limit negative", testKeys(handler, allKeys, -10, ""))
+	})
+
+	// this subtest confirms that all keys are are listed for every node in correct order
+	// and that for one node different pagination options are correct
+	t.Run("node keys", func(t *testing.T) {
+		var limitCheckAddr string
+
+		for addr, keys := range nodeKeys {
+			testKeys(handler, keys, 0, addr)(t)
+			if limitCheckAddr == "" {
+				limitCheckAddr = addr
+			}
+		}
+		testKeys(handler, nil, 0, invalidAddr)(t)
+
+		limitCheckKeys := nodeKeys[limitCheckAddr]
+		t.Run("limit 0", testKeys(handler, limitCheckKeys, 0, limitCheckAddr))
+		t.Run("limit default", testKeys(handler, limitCheckKeys, mock.DefaultLimit, limitCheckAddr))
+		t.Run("limit 2x default", testKeys(handler, limitCheckKeys, 2*mock.DefaultLimit, limitCheckAddr))
+		t.Run("limit 0.5x default", testKeys(handler, limitCheckKeys, mock.DefaultLimit/2, limitCheckAddr))
+		t.Run("limit max", testKeys(handler, limitCheckKeys, mock.MaxLimit, limitCheckAddr))
+		t.Run("limit 2x max", testKeys(handler, limitCheckKeys, 2*mock.MaxLimit, limitCheckAddr))
+		t.Run("limit negative", testKeys(handler, limitCheckKeys, -10, limitCheckAddr))
+	})
+
+	// this subtest confirms that all nodes are are listed in correct order with expected pagination
+	t.Run("nodes", func(t *testing.T) {
+		var allNodes []string
+		for addr := range nodeKeys {
+			allNodes = append(allNodes, addr)
+		}
+		sortCaseInsensitive(allNodes)
+
+		t.Run("limit 0", testNodes(handler, allNodes, 0, ""))
+		t.Run("limit default", testNodes(handler, allNodes, mock.DefaultLimit, ""))
+		t.Run("limit 2x default", testNodes(handler, allNodes, 2*mock.DefaultLimit, ""))
+		t.Run("limit 0.5x default", testNodes(handler, allNodes, mock.DefaultLimit/2, ""))
+		t.Run("limit max", testNodes(handler, allNodes, mock.MaxLimit, ""))
+		t.Run("limit 2x max", testNodes(handler, allNodes, 2*mock.MaxLimit, ""))
+		t.Run("limit negative", testNodes(handler, allNodes, -10, ""))
+	})
+
+	// this subtest confirms that all nodes are are listed that contain a a particular key in correct order
+	// and that for one key different node pagination options are correct
+	t.Run("key nodes", func(t *testing.T) {
+		var limitCheckKey string
+
+		for key, addrs := range keyNodes {
+			testNodes(handler, addrs, 0, key)(t)
+			if limitCheckKey == "" {
+				limitCheckKey = key
+			}
+		}
+		testNodes(handler, nil, 0, invalidKey)(t)
+
+		limitCheckKeys := keyNodes[limitCheckKey]
+		t.Run("limit 0", testNodes(handler, limitCheckKeys, 0, limitCheckKey))
+		t.Run("limit default", testNodes(handler, limitCheckKeys, mock.DefaultLimit, limitCheckKey))
+		t.Run("limit 2x default", testNodes(handler, limitCheckKeys, 2*mock.DefaultLimit, limitCheckKey))
+		t.Run("limit 0.5x default", testNodes(handler, limitCheckKeys, mock.DefaultLimit/2, limitCheckKey))
+		t.Run("limit max", testNodes(handler, limitCheckKeys, mock.MaxLimit, limitCheckKey))
+		t.Run("limit 2x max", testNodes(handler, limitCheckKeys, 2*mock.MaxLimit, limitCheckKey))
+		t.Run("limit negative", testNodes(handler, limitCheckKeys, -10, limitCheckKey))
+	})
+}
+
+// testsKeys returns a test function that validates wantKeys against a series of /api/keys
+// HTTP responses with provided limit and node options.
+func testKeys(handler http.Handler, wantKeys []string, limit int, node string) func(t *testing.T) {
+	return func(t *testing.T) {
+		t.Helper()
+
+		wantLimit := limit
+		if wantLimit <= 0 {
+			wantLimit = mock.DefaultLimit
+		}
+		if wantLimit > mock.MaxLimit {
+			wantLimit = mock.MaxLimit
+		}
+		wantKeysLen := len(wantKeys)
+		var i int
+		var startKey string
+		for {
+			var wantNext string
+			start := i * wantLimit
+			end := (i + 1) * wantLimit
+			if end < wantKeysLen {
+				wantNext = wantKeys[end]
+			} else {
+				end = wantKeysLen
+			}
+			testKeysResponse(t, handler, node, startKey, limit, KeysResponse{
+				Keys: wantKeys[start:end],
+				Next: wantNext,
+			})
+			if wantNext == "" {
+				break
+			}
+			startKey = wantNext
+			i++
+		}
+	}
+}
+
+// testNodes returns a test function that validates wantAddrs against a series of /api/nodes
+// HTTP responses with provided limit and key options.
+func testNodes(handler http.Handler, wantAddrs []string, limit int, key string) func(t *testing.T) {
+	return func(t *testing.T) {
+		t.Helper()
+
+		wantLimit := limit
+		if wantLimit <= 0 {
+			wantLimit = mock.DefaultLimit
+		}
+		if wantLimit > mock.MaxLimit {
+			wantLimit = mock.MaxLimit
+		}
+		wantAddrsLen := len(wantAddrs)
+		var i int
+		var startKey string
+		for {
+			var wantNext string
+			start := i * wantLimit
+			end := (i + 1) * wantLimit
+			if end < wantAddrsLen {
+				wantNext = wantAddrs[end]
+			} else {
+				end = wantAddrsLen
+			}
+			testNodesResponse(t, handler, key, startKey, limit, NodesResponse{
+				Nodes: wantAddrs[start:end],
+				Next:  wantNext,
+			})
+			if wantNext == "" {
+				break
+			}
+			startKey = wantNext
+			i++
+		}
+	}
+}
+
+// testStatusResponse validates a response made on url if it matches
+// the expected StatusResponse.
+func testStatusResponse(t *testing.T, handler http.Handler, url string, code int) {
+	t.Helper()
+
+	resp := httpGet(t, handler, url)
+
+	if resp.StatusCode != code {
+		t.Errorf("got status code %v, want %v", resp.StatusCode, code)
+	}
+	if got := resp.Header.Get("Content-Type"); got != jsonContentType {
+		t.Errorf("got Content-Type header %q, want %q", got, jsonContentType)
+	}
+	var r StatusResponse
+	if err := json.NewDecoder(resp.Body).Decode(&r); err != nil {
+		t.Fatal(err)
+	}
+	if r.Code != code {
+		t.Errorf("got response code %v, want %v", r.Code, code)
+	}
+	if r.Message != http.StatusText(code) {
+		t.Errorf("got response message %q, want %q", r.Message, http.StatusText(code))
+	}
+}
+
+// testKeysResponse validates response returned from handler on /api/keys
+// with node, start and limit options against KeysResponse.
+func testKeysResponse(t *testing.T, handler http.Handler, node, start string, limit int, want KeysResponse) {
+	t.Helper()
+
+	u, err := url.Parse("/api/keys")
+	if err != nil {
+		t.Fatal(err)
+	}
+	q := u.Query()
+	if node != "" {
+		q.Set("node", node)
+	}
+	if start != "" {
+		q.Set("start", start)
+	}
+	if limit != 0 {
+		q.Set("limit", strconv.Itoa(limit))
+	}
+	u.RawQuery = q.Encode()
+
+	resp := httpGet(t, handler, u.String())
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("got status code %v, want %v", resp.StatusCode, http.StatusOK)
+	}
+	if got := resp.Header.Get("Content-Type"); got != jsonContentType {
+		t.Errorf("got Content-Type header %q, want %q", got, jsonContentType)
+	}
+	var r KeysResponse
+	if err := json.NewDecoder(resp.Body).Decode(&r); err != nil {
+		t.Fatal(err)
+	}
+	if fmt.Sprint(r.Keys) != fmt.Sprint(want.Keys) {
+		t.Errorf("got keys %v, want %v", r.Keys, want.Keys)
+	}
+	if r.Next != want.Next {
+		t.Errorf("got next %s, want %s", r.Next, want.Next)
+	}
+}
+
+// testNodesResponse validates response returned from handler on /api/nodes
+// with key, start and limit options against NodesResponse.
+func testNodesResponse(t *testing.T, handler http.Handler, key, start string, limit int, want NodesResponse) {
+	t.Helper()
+
+	u, err := url.Parse("/api/nodes")
+	if err != nil {
+		t.Fatal(err)
+	}
+	q := u.Query()
+	if key != "" {
+		q.Set("key", key)
+	}
+	if start != "" {
+		q.Set("start", start)
+	}
+	if limit != 0 {
+		q.Set("limit", strconv.Itoa(limit))
+	}
+	u.RawQuery = q.Encode()
+
+	resp := httpGet(t, handler, u.String())
+
+	if resp.StatusCode != http.StatusOK {
+		t.Errorf("got status code %v, want %v", resp.StatusCode, http.StatusOK)
+	}
+	if got := resp.Header.Get("Content-Type"); got != jsonContentType {
+		t.Errorf("got Content-Type header %q, want %q", got, jsonContentType)
+	}
+	var r NodesResponse
+	if err := json.NewDecoder(resp.Body).Decode(&r); err != nil {
+		t.Fatal(err)
+	}
+	if fmt.Sprint(r.Nodes) != fmt.Sprint(want.Nodes) {
+		t.Errorf("got nodes %v, want %v", r.Nodes, want.Nodes)
+	}
+	if r.Next != want.Next {
+		t.Errorf("got next %s, want %s", r.Next, want.Next)
+	}
+}
+
+// httpGet uses httptest recorder to provide a response on handler's url.
+func httpGet(t *testing.T, handler http.Handler, url string) (r *http.Response) {
+	t.Helper()
+
+	req, err := http.NewRequest(http.MethodGet, url, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	w := httptest.NewRecorder()
+	handler.ServeHTTP(w, req)
+	return w.Result()
+}
+
+// sortCaseInsensitive performs a case insensitive sort on a string slice.
+func sortCaseInsensitive(s []string) {
+	sort.Slice(s, func(i, j int) bool {
+		return strings.ToLower(s[i]) < strings.ToLower(s[j])
+	})
+}

swarm/storage/mock/explorer/headers_test.go

@@ -0,0 +1,163 @@
+// Copyright 2019 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package explorer
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/swarm/storage/mock/mem"
+)
+
+// TestHandler_CORSOrigin validates that the correct Access-Control-Allow-Origin
+// header is served with various allowed origin settings.
+func TestHandler_CORSOrigin(t *testing.T) {
+	notAllowedOrigin := "http://not-allowed-origin.com/"
+
+	for _, tc := range []struct {
+		name    string
+		origins []string
+	}{
+		{
+			name:    "no origin",
+			origins: nil,
+		},
+		{
+			name:    "single origin",
+			origins: []string{"http://localhost/"},
+		},
+		{
+			name:    "multiple origins",
+			origins: []string{"http://localhost/", "http://ethereum.org/"},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			handler := NewHandler(mem.NewGlobalStore(), tc.origins)
+
+			origins := tc.origins
+			if origins == nil {
+				// handle the "no origin" test case
+				origins = []string{""}
+			}
+
+			for _, origin := range origins {
+				t.Run(fmt.Sprintf("get %q", origin), newTestCORSOrigin(handler, origin, origin))
+				t.Run(fmt.Sprintf("preflight %q", origin), newTestCORSPreflight(handler, origin, origin))
+			}
+
+			t.Run(fmt.Sprintf("get %q", notAllowedOrigin), newTestCORSOrigin(handler, notAllowedOrigin, ""))
+			t.Run(fmt.Sprintf("preflight %q", notAllowedOrigin), newTestCORSPreflight(handler, notAllowedOrigin, ""))
+		})
+	}
+
+	t.Run("wildcard", func(t *testing.T) {
+		handler := NewHandler(mem.NewGlobalStore(), []string{"*"})
+
+		for _, origin := range []string{
+			"http://example.com/",
+			"http://ethereum.org",
+			"http://localhost",
+		} {
+			t.Run(fmt.Sprintf("get %q", origin), newTestCORSOrigin(handler, origin, origin))
+			t.Run(fmt.Sprintf("preflight %q", origin), newTestCORSPreflight(handler, origin, origin))
+		}
+	})
+}
+
+// newTestCORSOrigin returns a test function that validates if wantOrigin CORS header is
+// served by the handler for a GET request.
+func newTestCORSOrigin(handler http.Handler, origin, wantOrigin string) func(t *testing.T) {
+	return func(t *testing.T) {
+		req, err := http.NewRequest(http.MethodGet, "/", nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		req.Header.Set("Origin", origin)
+
+		w := httptest.NewRecorder()
+		handler.ServeHTTP(w, req)
+		resp := w.Result()
+
+		header := resp.Header.Get("Access-Control-Allow-Origin")
+		if header != wantOrigin {
+			t.Errorf("got Access-Control-Allow-Origin header %q, want %q", header, wantOrigin)
+		}
+	}
+}
+
+// newTestCORSPreflight returns a test function that validates if wantOrigin CORS header is
+// served by the handler for an OPTIONS CORS preflight request.
+func newTestCORSPreflight(handler http.Handler, origin, wantOrigin string) func(t *testing.T) {
+	return func(t *testing.T) {
+		req, err := http.NewRequest(http.MethodOptions, "/", nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		req.Header.Set("Origin", origin)
+		req.Header.Set("Access-Control-Request-Method", "GET")
+
+		w := httptest.NewRecorder()
+		handler.ServeHTTP(w, req)
+		resp := w.Result()
+
+		header := resp.Header.Get("Access-Control-Allow-Origin")
+		if header != wantOrigin {
+			t.Errorf("got Access-Control-Allow-Origin header %q, want %q", header, wantOrigin)
+		}
+	}
+}
+
+// TestHandler_noCacheHeaders validates that no cache headers are server.
+func TestHandler_noCacheHeaders(t *testing.T) {
+	handler := NewHandler(mem.NewGlobalStore(), nil)
+
+	for _, tc := range []struct {
+		url string
+	}{
+		{
+			url: "/",
+		},
+		{
+			url: "/api/nodes",
+		},
+		{
+			url: "/api/keys",
+		},
+	} {
+		req, err := http.NewRequest(http.MethodGet, tc.url, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		w := httptest.NewRecorder()
+		handler.ServeHTTP(w, req)
+		resp := w.Result()
+
+		for header, want := range map[string]string{
+			"Cache-Control": "no-cache, no-store, must-revalidate",
+			"Pragma":        "no-cache",
+			"Expires":       "0",
+		} {
+			got := resp.Header.Get(header)
+			if got != want {
+				t.Errorf("got %q header %q for url %q, want %q", header, tc.url, got, want)
+			}
+		}
+	}
+}

swarm/storage/mock/explorer/swagger.yaml

@@ -0,0 +1,176 @@
+swagger: '2.0'
+info:
+  title: Swarm Global Store API
+  version: 0.1.0
+tags:
+  - name: Has Key
+    description: Checks if a Key is stored on a Node
+  - name: Keys
+    description: Lists Keys
+  - name: Nodes
+    description: Lists Node addresses
+
+paths:
+  '/api/has-key/{node}/{key}':
+    get:
+      tags:
+        - Has Key
+      summary: Checks if a Key is stored on a Node
+      operationId: hasKey
+      produces:
+        - application/json
+
+      parameters:
+        - name: node
+          in: path
+          required: true
+          type: string
+          format: hex-endoded
+          description: Node address.
+
+        - name: key
+          in: path
+          required: true
+          type: string
+          format: hex-endoded
+          description: Key.
+
+      responses:
+        '200':
+          description: Key is stored on Node
+          schema:
+            $ref: '#/definitions/Status'
+        '404':
+          description: Key is not stored on Node
+          schema:
+            $ref: '#/definitions/Status'
+        '500':
+          description: Internal Server Error
+          schema:
+            $ref: '#/definitions/Status'
+
+  '/api/keys':
+    get:
+      tags:
+        - Keys
+      summary: Lists Keys
+      operationId: keys
+      produces:
+        - application/json
+
+      parameters:
+        - name: start
+          in: query
+          required: false
+          type: string
+          format: hex-encoded Key
+          description: A Key as the starting point for the returned list. It is usually a value from the returned "next" field in the Keys repsonse.
+
+        - name: limit
+          in: query
+          required: false
+          type: integer
+          default: 100
+          minimum: 1
+          maximum: 1000
+          description: Limits the number of Keys returned in on response.
+
+        - name: node
+          in: query
+          required: false
+          type: string
+          format: hex-encoded Node address
+          description: If this parameter is provided, only Keys that are stored on this Node be returned in the response. If not, all known Keys will be returned.
+
+      responses:
+        '200':
+          description: List of Keys
+          schema:
+            $ref: '#/definitions/Keys'
+        '500':
+          description: Internal Server Error
+          schema:
+            $ref: '#/definitions/Status'
+
+  '/api/nodes':
+    get:
+      tags:
+        - Nodes
+      summary: Lists Node addresses
+      operationId: nodes
+      produces:
+        - application/json
+
+      parameters:
+        - name: start
+          in: query
+          required: false
+          type: string
+          format: hex-encoded Node address
+          description: A Node address as the starting point for the returned list. It is usually a value from the returned "next" field in the Nodes repsonse.
+
+        - name: limit
+          in: query
+          required: false
+          type: integer
+          default: 100
+          minimum: 1
+          maximum: 1000
+          description: Limits the number of Node addresses returned in on response.
+
+        - name: key
+          in: query
+          required: false
+          type: string
+          format: hex-encoded Key
+          description: If this parameter is provided, only addresses of Nodes that store this Key will be returned in the response. If not, all known Node addresses will be returned.
+    
+      responses:
+        '200':
+          description: List of Node addresses
+          schema:
+            $ref: '#/definitions/Nodes'
+        '500':
+          description: Internal Server Error
+          schema:
+            $ref: '#/definitions/Status'
+
+definitions:
+
+  Status:
+    type: object
+    properties:
+      message:
+        type: string
+        description: HTTP Status Code name.
+      code:
+        type: integer
+        description: HTTP Status Code.
+
+  Keys:
+    type: object
+    properties:
+      keys:
+        type: array
+        description: A list of Keys.
+        items:
+          type: string
+          format: hex-encoded Key
+      next:
+        type: string
+        format: hex-encoded Key
+        description: If present, the next Key in listing. Can be passed as "start" query parameter to continue the listing. If not present, the end of the listing is reached.
+
+  Nodes:
+    type: object
+    properties:
+      nodes:
+        type: array
+        description: A list of Node addresses.
+        items:
+          type: string
+          format: hex-encoded Node address
+      next:
+        type: string
+        format: hex-encoded Node address
+        description: If present, the next Node address in listing. Can be passed as "start" query parameter to continue the listing. If not present, the end of the listing is reached.

swarm/storage/mock/mem/mem.go

@@ -25,6 +25,7 @@ import (
 	"encoding/json"
 	"io"
 	"io/ioutil"
+	"sort"
 	"sync"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -34,16 +35,27 @@ import (
 // GlobalStore stores all chunk data and also keys and node addresses relations.
 // It implements mock.GlobalStore interface.
 type GlobalStore struct {
-	nodes map[string]map[common.Address]struct{}
-	data  map[string][]byte
-	mu    sync.Mutex
+	// holds a slice of keys per node
+	nodeKeys map[common.Address][][]byte
+	// holds which key is stored on which nodes
+	keyNodes map[string][]common.Address
+	// all node addresses
+	nodes []common.Address
+	// all keys
+	keys [][]byte
+	// all keys data
+	data map[string][]byte
+	mu   sync.RWMutex
 }
 
 // NewGlobalStore creates a new instance of GlobalStore.
 func NewGlobalStore() *GlobalStore {
 	return &GlobalStore{
-		nodes: make(map[string]map[common.Address]struct{}),
-		data:  make(map[string][]byte),
+		nodeKeys: make(map[common.Address][][]byte),
+		keyNodes: make(map[string][]common.Address),
+		nodes:    make([]common.Address, 0),
+		keys:     make([][]byte, 0),
+		data:     make(map[string][]byte),
 	}
 }
 
@@ -56,10 +68,10 @@ func (s *GlobalStore) NewNodeStore(addr common.Address) *mock.NodeStore {
 // Get returns chunk data if the chunk with key exists for node
 // on address addr.
 func (s *GlobalStore) Get(addr common.Address, key []byte) (data []byte, err error) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
+	s.mu.RLock()
+	defer s.mu.RUnlock()
 
-	if _, ok := s.nodes[string(key)][addr]; !ok {
+	if _, has := s.nodeKeyIndex(addr, key); !has {
 		return nil, mock.ErrNotFound
 	}
 
@@ -75,11 +87,33 @@ func (s *GlobalStore) Put(addr common.Address, key []byte, data []byte) error {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	if _, ok := s.nodes[string(key)]; !ok {
-		s.nodes[string(key)] = make(map[common.Address]struct{})
+	if i, found := s.nodeKeyIndex(addr, key); !found {
+		s.nodeKeys[addr] = append(s.nodeKeys[addr], nil)
+		copy(s.nodeKeys[addr][i+1:], s.nodeKeys[addr][i:])
+		s.nodeKeys[addr][i] = key
+	}
+
+	if i, found := s.keyNodeIndex(key, addr); !found {
+		k := string(key)
+		s.keyNodes[k] = append(s.keyNodes[k], addr)
+		copy(s.keyNodes[k][i+1:], s.keyNodes[k][i:])
+		s.keyNodes[k][i] = addr
+	}
+
+	if i, found := s.nodeIndex(addr); !found {
+		s.nodes = append(s.nodes, addr)
+		copy(s.nodes[i+1:], s.nodes[i:])
+		s.nodes[i] = addr
+	}
+
+	if i, found := s.keyIndex(key); !found {
+		s.keys = append(s.keys, nil)
+		copy(s.keys[i+1:], s.keys[i:])
+		s.keys[i] = key
 	}
-	s.nodes[string(key)][addr] = struct{}{}
+
 	s.data[string(key)] = data
+
 	return nil
 }
 
@@ -88,24 +122,177 @@ func (s *GlobalStore) Delete(addr common.Address, key []byte) error {
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
-	var count int
-	if _, ok := s.nodes[string(key)]; ok {
-		delete(s.nodes[string(key)], addr)
-		count = len(s.nodes[string(key)])
+	if i, has := s.nodeKeyIndex(addr, key); has {
+		s.nodeKeys[addr] = append(s.nodeKeys[addr][:i], s.nodeKeys[addr][i+1:]...)
+	}
+
+	k := string(key)
+	if i, on := s.keyNodeIndex(key, addr); on {
+		s.keyNodes[k] = append(s.keyNodes[k][:i], s.keyNodes[k][i+1:]...)
 	}
-	if count == 0 {
-		delete(s.data, string(key))
+
+	if len(s.nodeKeys[addr]) == 0 {
+		if i, found := s.nodeIndex(addr); found {
+			s.nodes = append(s.nodes[:i], s.nodes[i+1:]...)
+		}
+	}
+
+	if len(s.keyNodes[k]) == 0 {
+		if i, found := s.keyIndex(key); found {
+			s.keys = append(s.keys[:i], s.keys[i+1:]...)
+		}
 	}
 	return nil
 }
 
 // HasKey returns whether a node with addr contains the key.
-func (s *GlobalStore) HasKey(addr common.Address, key []byte) bool {
-	s.mu.Lock()
-	defer s.mu.Unlock()
+func (s *GlobalStore) HasKey(addr common.Address, key []byte) (yes bool) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	_, yes = s.nodeKeyIndex(addr, key)
+	return yes
+}
+
+// keyIndex returns the index of a key in keys slice.
+func (s *GlobalStore) keyIndex(key []byte) (index int, found bool) {
+	l := len(s.keys)
+	index = sort.Search(l, func(i int) bool {
+		return bytes.Compare(s.keys[i], key) >= 0
+	})
+	found = index < l && bytes.Equal(s.keys[index], key)
+	return index, found
+}
+
+// nodeIndex returns the index of a node address in nodes slice.
+func (s *GlobalStore) nodeIndex(addr common.Address) (index int, found bool) {
+	l := len(s.nodes)
+	index = sort.Search(l, func(i int) bool {
+		return bytes.Compare(s.nodes[i][:], addr[:]) >= 0
+	})
+	found = index < l && bytes.Equal(s.nodes[index][:], addr[:])
+	return index, found
+}
+
+// nodeKeyIndex returns the index of a key in nodeKeys slice.
+func (s *GlobalStore) nodeKeyIndex(addr common.Address, key []byte) (index int, found bool) {
+	l := len(s.nodeKeys[addr])
+	index = sort.Search(l, func(i int) bool {
+		return bytes.Compare(s.nodeKeys[addr][i], key) >= 0
+	})
+	found = index < l && bytes.Equal(s.nodeKeys[addr][index], key)
+	return index, found
+}
+
+// keyNodeIndex returns the index of a node address in keyNodes slice.
+func (s *GlobalStore) keyNodeIndex(key []byte, addr common.Address) (index int, found bool) {
+	k := string(key)
+	l := len(s.keyNodes[k])
+	index = sort.Search(l, func(i int) bool {
+		return bytes.Compare(s.keyNodes[k][i][:], addr[:]) >= 0
+	})
+	found = index < l && s.keyNodes[k][index] == addr
+	return index, found
+}
+
+// Keys returns a paginated list of keys on all nodes.
+func (s *GlobalStore) Keys(startKey []byte, limit int) (keys mock.Keys, err error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	var i int
+	if startKey != nil {
+		i, _ = s.keyIndex(startKey)
+	}
+	total := len(s.keys)
+	max := maxIndex(i, limit, total)
+	keys.Keys = make([][]byte, 0, max-i)
+	for ; i < max; i++ {
+		keys.Keys = append(keys.Keys, append([]byte(nil), s.keys[i]...))
+	}
+	if total > max {
+		keys.Next = s.keys[max]
+	}
+	return keys, nil
+}
+
+// Nodes returns a paginated list of all known nodes.
+func (s *GlobalStore) Nodes(startAddr *common.Address, limit int) (nodes mock.Nodes, err error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	var i int
+	if startAddr != nil {
+		i, _ = s.nodeIndex(*startAddr)
+	}
+	total := len(s.nodes)
+	max := maxIndex(i, limit, total)
+	nodes.Addrs = make([]common.Address, 0, max-i)
+	for ; i < max; i++ {
+		nodes.Addrs = append(nodes.Addrs, s.nodes[i])
+	}
+	if total > max {
+		nodes.Next = &s.nodes[max]
+	}
+	return nodes, nil
+}
+
+// NodeKeys returns a paginated list of keys on a node with provided address.
+func (s *GlobalStore) NodeKeys(addr common.Address, startKey []byte, limit int) (keys mock.Keys, err error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	var i int
+	if startKey != nil {
+		i, _ = s.nodeKeyIndex(addr, startKey)
+	}
+	total := len(s.nodeKeys[addr])
+	max := maxIndex(i, limit, total)
+	keys.Keys = make([][]byte, 0, max-i)
+	for ; i < max; i++ {
+		keys.Keys = append(keys.Keys, append([]byte(nil), s.nodeKeys[addr][i]...))
+	}
+	if total > max {
+		keys.Next = s.nodeKeys[addr][max]
+	}
+	return keys, nil
+}
+
+// KeyNodes returns a paginated list of nodes that contain a particular key.
+func (s *GlobalStore) KeyNodes(key []byte, startAddr *common.Address, limit int) (nodes mock.Nodes, err error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
 
-	_, ok := s.nodes[string(key)][addr]
-	return ok
+	var i int
+	if startAddr != nil {
+		i, _ = s.keyNodeIndex(key, *startAddr)
+	}
+	total := len(s.keyNodes[string(key)])
+	max := maxIndex(i, limit, total)
+	nodes.Addrs = make([]common.Address, 0, max-i)
+	for ; i < max; i++ {
+		nodes.Addrs = append(nodes.Addrs, s.keyNodes[string(key)][i])
+	}
+	if total > max {
+		nodes.Next = &s.keyNodes[string(key)][max]
+	}
+	return nodes, nil
+}
+
+// maxIndex returns the end index for one page listing
+// based on the start index, limit and total number of elements.
+func maxIndex(start, limit, total int) (max int) {
+	if limit <= 0 {
+		limit = mock.DefaultLimit
+	}
+	if limit > mock.MaxLimit {
+		limit = mock.MaxLimit
+	}
+	max = total
+	if start+limit < max {
+		max = start + limit
+	}
+	return max
 }
 
 // Import reads tar archive from a reader that contains exported chunk data.
@@ -135,14 +322,26 @@ func (s *GlobalStore) Import(r io.Reader) (n int, err error) {
 			return n, err
 		}
 
-		addrs := make(map[common.Address]struct{})
-		for _, a := range c.Addrs {
-			addrs[a] = struct{}{}
+		key := common.Hex2Bytes(hdr.Name)
+		s.keyNodes[string(key)] = c.Addrs
+		for _, addr := range c.Addrs {
+			if i, has := s.nodeKeyIndex(addr, key); !has {
+				s.nodeKeys[addr] = append(s.nodeKeys[addr], nil)
+				copy(s.nodeKeys[addr][i+1:], s.nodeKeys[addr][i:])
+				s.nodeKeys[addr][i] = key
+			}
+			if i, found := s.nodeIndex(addr); !found {
+				s.nodes = append(s.nodes, addr)
+				copy(s.nodes[i+1:], s.nodes[i:])
+				s.nodes[i] = addr
+			}
 		}
-
-		key := string(common.Hex2Bytes(hdr.Name))
-		s.nodes[key] = addrs
-		s.data[key] = c.Data
+		if i, found := s.keyIndex(key); !found {
+			s.keys = append(s.keys, nil)
+			copy(s.keys[i+1:], s.keys[i:])
+			s.keys[i] = key
+		}
+		s.data[string(key)] = c.Data
 		n++
 	}
 	return n, err
@@ -151,23 +350,18 @@ func (s *GlobalStore) Import(r io.Reader) (n int, err error) {
 // Export writes to a writer a tar archive with all chunk data from
 // the store. It returns the number of chunks exported and an error.
 func (s *GlobalStore) Export(w io.Writer) (n int, err error) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
+	s.mu.RLock()
+	defer s.mu.RUnlock()
 
 	tw := tar.NewWriter(w)
 	defer tw.Close()
 
 	buf := bytes.NewBuffer(make([]byte, 0, 1024))
 	encoder := json.NewEncoder(buf)
-	for key, addrs := range s.nodes {
-		al := make([]common.Address, 0, len(addrs))
-		for a := range addrs {
-			al = append(al, a)
-		}
-
+	for key, addrs := range s.keyNodes {
 		buf.Reset()
 		if err = encoder.Encode(mock.ExportedChunk{
-			Addrs: al,
+			Addrs: addrs,
 			Data:  s.data[key],
 		}); err != nil {
 			return n, err

swarm/storage/mock/mem/mem_test.go

@@ -28,6 +28,12 @@ func TestGlobalStore(t *testing.T) {
 	test.MockStore(t, NewGlobalStore(), 100)
 }
 
+// TestGlobalStoreListings is running test for a GlobalStore
+// using test.MockStoreListings function.
+func TestGlobalStoreListings(t *testing.T) {
+	test.MockStoreListings(t, NewGlobalStore(), 1000)
+}
+
 // TestImportExport is running tests for importing and
 // exporting data between two GlobalStores
 // using test.ImportExport function.

swarm/storage/mock/mock.go

@@ -39,6 +39,17 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 )
 
+const (
+	// DefaultLimit should be used as default limit for
+	// Keys, Nodes, NodeKeys and KeyNodes GlobarStorer
+	// methids implementations.
+	DefaultLimit = 100
+	// MaxLimit should be used as the maximal returned number
+	// of items for Keys, Nodes, NodeKeys and KeyNodes GlobarStorer
+	// methids implementations, regardless of provided limit.
+	MaxLimit = 1000
+)
+
 // ErrNotFound indicates that the chunk is not found.
 var ErrNotFound = errors.New("not found")
 
@@ -76,6 +87,10 @@ func (n *NodeStore) Delete(key []byte) error {
 	return n.store.Delete(n.addr, key)
 }
 
+func (n *NodeStore) Keys(startKey []byte, limit int) (keys Keys, err error) {
+	return n.store.NodeKeys(n.addr, startKey, limit)
+}
+
 // GlobalStorer defines methods for mock db store
 // that stores chunk data for all swarm nodes.
 // It is used in tests to construct mock NodeStores
@@ -85,12 +100,28 @@ type GlobalStorer interface {
 	Put(addr common.Address, key []byte, data []byte) error
 	Delete(addr common.Address, key []byte) error
 	HasKey(addr common.Address, key []byte) bool
+	Keys(startKey []byte, limit int) (keys Keys, err error)
+	Nodes(startAddr *common.Address, limit int) (nodes Nodes, err error)
+	NodeKeys(addr common.Address, startKey []byte, limit int) (keys Keys, err error)
+	KeyNodes(key []byte, startAddr *common.Address, limit int) (nodes Nodes, err error)
 	// NewNodeStore creates an instance of NodeStore
 	// to be used by a single swarm node with
 	// address addr.
 	NewNodeStore(addr common.Address) *NodeStore
 }
 
+// Keys are returned results by Keys and NodeKeys GlobalStorer methods.
+type Keys struct {
+	Keys [][]byte
+	Next []byte
+}
+
+// Nodes are returned results by Nodes and KeyNodes GlobalStorer methods.
+type Nodes struct {
+	Addrs []common.Address
+	Next  *common.Address
+}
+
 // Importer defines method for importing mock store data
 // from an exported tar archive.
 type Importer interface {

swarm/storage/mock/rpc/rpc.go

@@ -88,3 +88,27 @@ func (s *GlobalStore) HasKey(addr common.Address, key []byte) bool {
 	}
 	return has
 }
+
+// Keys returns a paginated list of keys on all nodes.
+func (s *GlobalStore) Keys(startKey []byte, limit int) (keys mock.Keys, err error) {
+	err = s.client.Call(&keys, "mockStore_keys", startKey, limit)
+	return keys, err
+}
+
+// Nodes returns a paginated list of all known nodes.
+func (s *GlobalStore) Nodes(startAddr *common.Address, limit int) (nodes mock.Nodes, err error) {
+	err = s.client.Call(&nodes, "mockStore_nodes", startAddr, limit)
+	return nodes, err
+}
+
+// NodeKeys returns a paginated list of keys on a node with provided address.
+func (s *GlobalStore) NodeKeys(addr common.Address, startKey []byte, limit int) (keys mock.Keys, err error) {
+	err = s.client.Call(&keys, "mockStore_nodeKeys", addr, startKey, limit)
+	return keys, err
+}
+
+// KeyNodes returns a paginated list of nodes that contain a particular key.
+func (s *GlobalStore) KeyNodes(key []byte, startAddr *common.Address, limit int) (nodes mock.Nodes, err error) {
+	err = s.client.Call(&nodes, "mockStore_keyNodes", key, startAddr, limit)
+	return nodes, err
+}

swarm/storage/mock/rpc/rpc_test.go

@@ -27,6 +27,27 @@ import (
 // TestDBStore is running test for a GlobalStore
 // using test.MockStore function.
 func TestRPCStore(t *testing.T) {
+	store, cleanup := newTestStore(t)
+	defer cleanup()
+
+	test.MockStore(t, store, 30)
+}
+
+// TestRPCStoreListings is running test for a GlobalStore
+// using test.MockStoreListings function.
+func TestRPCStoreListings(t *testing.T) {
+	store, cleanup := newTestStore(t)
+	defer cleanup()
+
+	test.MockStoreListings(t, store, 1000)
+}
+
+// newTestStore creates a temporary GlobalStore
+// that will be closed when returned cleanup function
+// is called.
+func newTestStore(t *testing.T) (s *GlobalStore, cleanup func()) {
+	t.Helper()
+
 	serverStore := mem.NewGlobalStore()
 
 	server := rpc.NewServer()
@@ -35,7 +56,9 @@ func TestRPCStore(t *testing.T) {
 	}
 
 	store := NewGlobalStore(rpc.DialInProc(server))
-	defer store.Close()
-
-	test.MockStore(t, store, 30)
+	return store, func() {
+		if err := store.Close(); err != nil {
+			t.Error(err)
+		}
+	}
 }

swarm/storage/mock/test/test.go

@@ -20,6 +20,7 @@ package test
 
 import (
 	"bytes"
+	"encoding/binary"
 	"fmt"
 	"io"
 	"strconv"
@@ -170,6 +171,123 @@ func MockStore(t *testing.T, globalStore mock.GlobalStorer, n int) {
 	})
 }
 
+// MockStoreListings tests global store methods Keys, Nodes, NodeKeys and KeyNodes.
+// It uses a provided globalstore to put chunks for n number of node addresses
+// and to validate that methods are returning the right responses.
+func MockStoreListings(t *testing.T, globalStore mock.GlobalStorer, n int) {
+	addrs := make([]common.Address, n)
+	for i := 0; i < n; i++ {
+		addrs[i] = common.HexToAddress(strconv.FormatInt(int64(i)+1, 16))
+	}
+	type chunk struct {
+		key  []byte
+		data []byte
+	}
+	const chunksPerNode = 5
+	keys := make([][]byte, n*chunksPerNode)
+	for i := 0; i < n*chunksPerNode; i++ {
+		b := make([]byte, 8)
+		binary.BigEndian.PutUint64(b, uint64(i))
+		keys[i] = b
+	}
+
+	// keep track of keys on every node
+	nodeKeys := make(map[common.Address][][]byte)
+	// keep track of nodes that store particular key
+	keyNodes := make(map[string][]common.Address)
+	for i := 0; i < chunksPerNode; i++ {
+		// put chunks for every address
+		for j := 0; j < n; j++ {
+			addr := addrs[j]
+			key := keys[(i*n)+j]
+			err := globalStore.Put(addr, key, []byte("data"))
+			if err != nil {
+				t.Fatal(err)
+			}
+			nodeKeys[addr] = append(nodeKeys[addr], key)
+			keyNodes[string(key)] = append(keyNodes[string(key)], addr)
+		}
+
+		// test Keys method
+		var startKey []byte
+		var gotKeys [][]byte
+		for {
+			keys, err := globalStore.Keys(startKey, 0)
+			if err != nil {
+				t.Fatal(err)
+			}
+			gotKeys = append(gotKeys, keys.Keys...)
+			if keys.Next == nil {
+				break
+			}
+			startKey = keys.Next
+		}
+		wantKeys := keys[:(i+1)*n]
+		if fmt.Sprint(gotKeys) != fmt.Sprint(wantKeys) {
+			t.Fatalf("got #%v keys %v, want %v", i+1, gotKeys, wantKeys)
+		}
+
+		// test Nodes method
+		var startNode *common.Address
+		var gotNodes []common.Address
+		for {
+			nodes, err := globalStore.Nodes(startNode, 0)
+			if err != nil {
+				t.Fatal(err)
+			}
+			gotNodes = append(gotNodes, nodes.Addrs...)
+			if nodes.Next == nil {
+				break
+			}
+			startNode = nodes.Next
+		}
+		wantNodes := addrs
+		if fmt.Sprint(gotNodes) != fmt.Sprint(wantNodes) {
+			t.Fatalf("got #%v nodes %v, want %v", i+1, gotNodes, wantNodes)
+		}
+
+		// test NodeKeys method
+		for addr, wantKeys := range nodeKeys {
+			var startKey []byte
+			var gotKeys [][]byte
+			for {
+				keys, err := globalStore.NodeKeys(addr, startKey, 0)
+				if err != nil {
+					t.Fatal(err)
+				}
+				gotKeys = append(gotKeys, keys.Keys...)
+				if keys.Next == nil {
+					break
+				}
+				startKey = keys.Next
+			}
+			if fmt.Sprint(gotKeys) != fmt.Sprint(wantKeys) {
+				t.Fatalf("got #%v %s node keys %v, want %v", i+1, addr.Hex(), gotKeys, wantKeys)
+			}
+		}
+
+		// test KeyNodes method
+		for key, wantNodes := range keyNodes {
+			var startNode *common.Address
+			var gotNodes []common.Address
+			for {
+				nodes, err := globalStore.KeyNodes([]byte(key), startNode, 0)
+				if err != nil {
+					t.Fatal(err)
+				}
+				gotNodes = append(gotNodes, nodes.Addrs...)
+				if nodes.Next == nil {
+					break
+				}
+				startNode = nodes.Next
+			}
+			if fmt.Sprint(gotNodes) != fmt.Sprint(wantNodes) {
+				t.Fatalf("got #%v %x key nodes %v, want %v", i+1, []byte(key), gotNodes, wantNodes)
+			}
+		}
+	}
+}
+
 // ImportExport saves chunks to the outStore, exports them to the tar archive,
 // imports tar archive to the inStore and checks if all chunks are imported correctly.
 func ImportExport(t *testing.T, outStore, inStore mock.GlobalStorer, n int) {