Merge pull request #5372 from raulk/dns-resolution-api-endpoint

Run DNS lookup for --api endpoint provided in CLI

cmd/ipfs/dnsresolve_test.go

+package main
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"strings"
+	"testing"
+
+	ma "gx/ipfs/QmYmsdtJ3HsodkePE3eU3TsCaP2YvPZJ4LoXnNkDE5Tpt7/go-multiaddr"
+	madns "gx/ipfs/QmfXU2MhWoegxHoeMd3A2ytL2P6CY4FfqGWc23LTNWBwZt/go-multiaddr-dns"
+)
+
+var (
+	ctx         = context.Background()
+	testAddr, _ = ma.NewMultiaddr("/dns4/example.com/tcp/5001")
+)
+
+func makeResolver(n uint8) *madns.Resolver {
+	results := make([]net.IPAddr, n)
+	for i := uint8(0); i < n; i++ {
+		results[i] = net.IPAddr{IP: net.ParseIP(fmt.Sprintf("192.0.2.%d", i))}
+	}
+
+	backend := &madns.MockBackend{
+		IP: map[string][]net.IPAddr{
+			"example.com": results,
+		}}
+
+	return &madns.Resolver{
+		Backend: backend,
+	}
+}
+
+func TestApiEndpointResolveDNSOneResult(t *testing.T) {
+	dnsResolver = makeResolver(1)
+
+	addr, err := resolveAddr(ctx, testAddr)
+	if err != nil {
+		t.Error(err)
+	}
+
+	if ref, _ := ma.NewMultiaddr("/ip4/192.0.2.0/tcp/5001"); !addr.Equal(ref) {
+		t.Errorf("resolved address was different than expected")
+	}
+}
+
+func TestApiEndpointResolveDNSMultipleResults(t *testing.T) {
+	dnsResolver = makeResolver(4)
+
+	addr, err := resolveAddr(ctx, testAddr)
+	if err != nil {
+		t.Error(err)
+	}
+
+	if ref, _ := ma.NewMultiaddr("/ip4/192.0.2.0/tcp/5001"); !addr.Equal(ref) {
+		t.Errorf("resolved address was different than expected")
+	}
+}
+
+func TestApiEndpointResolveDNSNoResults(t *testing.T) {
+	dnsResolver = makeResolver(0)
+
+	addr, err := resolveAddr(ctx, testAddr)
+	if addr != nil || err == nil {
+		t.Error("expected test address not to resolve, and to throw an error")
+	}
+
+	if !strings.HasPrefix(err.Error(), "non-resolvable API endpoint") {
+		t.Errorf("expected error not thrown; actual: %v", err)
+	}
+}

cmd/ipfs/main.go

@@ -34,6 +34,7 @@ import (
 	osh "gx/ipfs/QmXuBJ7DR6k3rmUEKtvVMhwjmXDuJgXXPUt4LQXKBMsU93/go-os-helper"
 	ma "gx/ipfs/QmYmsdtJ3HsodkePE3eU3TsCaP2YvPZJ4LoXnNkDE5Tpt7/go-multiaddr"
 	loggables "gx/ipfs/QmZ4zF1mBrt8C2mSCM4ZYE4aAnv78f7GvrzufJC4G5tecK/go-libp2p-loggables"
+	madns "gx/ipfs/QmfXU2MhWoegxHoeMd3A2ytL2P6CY4FfqGWc23LTNWBwZt/go-multiaddr-dns"
 )
 
 // log is the command logger
@@ -41,6 +42,9 @@ var log = logging.Logger("cmd/ipfs")
 
 var errRequestCanceled = errors.New("request canceled")
 
+// declared as a var for testing purposes
+var dnsResolver = madns.DefaultResolver
+
 const (
 	EnvEnableProfiling = "IPFS_PROF"
 	cpuProfile         = "ipfs.cpuprof"
@@ -235,7 +239,7 @@ func commandShouldRunOnDaemon(details cmdDetails, req *cmds.Request, cctx *oldcm
 	// did user specify an api to use for this command?
 	apiAddrStr, _ := req.Options[corecmds.ApiOption].(string)
 
-	client, err := getApiClient(cctx.ConfigRoot, apiAddrStr)
+	client, err := getAPIClient(req.Context, cctx.ConfigRoot, apiAddrStr)
 	if err == repo.ErrApiNotRunning {
 		if apiAddrStr != "" && req.Command != daemonCmd {
 			// if user SPECIFIED an api, and this cmd is not daemon
@@ -403,10 +407,10 @@ If you're sure go-ipfs isn't running, you can just delete it.
 var checkIPFSUnixFmt = "Otherwise check:\n\tps aux | grep ipfs"
 var checkIPFSWinFmt = "Otherwise check:\n\ttasklist | findstr ipfs"
 
-// getApiClient checks the repo, and the given options, checking for
+// getAPIClient checks the repo, and the given options, checking for
 // a running API service. if there is one, it returns a client.
 // otherwise, it returns errApiNotRunning, or another error.
-func getApiClient(repoPath, apiAddrStr string) (http.Client, error) {
+func getAPIClient(ctx context.Context, repoPath, apiAddrStr string) (http.Client, error) {
 	var apiErrorFmt string
 	switch {
 	case osh.IsUnix():
@@ -440,10 +444,15 @@ func getApiClient(repoPath, apiAddrStr string) (http.Client, error) {
 	if len(addr.Protocols()) == 0 {
 		return nil, fmt.Errorf(apiErrorFmt, repoPath, "multiaddr doesn't provide any protocols")
 	}
-	return apiClientForAddr(addr)
+	return apiClientForAddr(ctx, addr)
 }
 
-func apiClientForAddr(addr ma.Multiaddr) (http.Client, error) {
+func apiClientForAddr(ctx context.Context, addr ma.Multiaddr) (http.Client, error) {
+	addr, err := resolveAddr(ctx, addr)
+	if err != nil {
+		return nil, err
+	}
+
 	_, host, err := manet.DialArgs(addr)
 	if err != nil {
 		return nil, err
@@ -451,3 +460,19 @@ func apiClientForAddr(addr ma.Multiaddr) (http.Client, error) {
 
 	return http.NewClient(host, http.ClientWithAPIPrefix(corehttp.APIPath)), nil
 }
+
+func resolveAddr(ctx context.Context, addr ma.Multiaddr) (ma.Multiaddr, error) {
+	ctx, cancelFunc := context.WithTimeout(ctx, 10*time.Second)
+	defer cancelFunc()
+
+	addrs, err := dnsResolver.Resolve(ctx, addr)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(addrs) == 0 {
+		return nil, errors.New("non-resolvable API endpoint")
+	}
+
+	return addrs[0], nil
+}

package.json

@@ -539,6 +539,12 @@
       "hash": "QmPyxJ2QS7L5FhGkNYkNcXHGjDhvGHueJ4auqAstFHYxy5",
       "name": "go-cidutil",
       "version": "0.0.2"
+    },
+    {
+      "author": "lgierth",
+      "hash": "QmfXU2MhWoegxHoeMd3A2ytL2P6CY4FfqGWc23LTNWBwZt",
+      "name": "go-multiaddr-dns",
+      "version": "0.2.4"
     }
   ],
   "gxVersion": "0.10.0",

test/sharness/t0236-cli-api-dns-resolve.sh

+#!/usr/bin/env bash
+#
+# Copyright (c) 2015 Jeromy Johnson
+# MIT Licensed; see the LICENSE file in this repository.
+#
+
+test_description="test dns resolution of api endpoint by cli"
+
+. lib/test-lib.sh
+
+test_init_ipfs
+
+test_expect_success "can make http request against dns resolved nc server" '
+  nc -ld 5005 > nc_out &
+  NCPID=$!
+  go-sleep 0.5s && kill "$NCPID" &
+  ipfs cat /ipfs/Qmabcdef --api /dns4/localhost/tcp/5005 || true
+'
+
+test_expect_success "request was received by local nc server" '
+  grep "POST /api/v0/cat" nc_out
+'
+
+test_done