Add helper for checking local peers

CONTRIBUTING.md

@@ -183,7 +183,8 @@ you can run those with `task test-unit` after starting the environment as descri
 
 We also have a set of "integration" tests in the `integration` directory.
 They use the Go MongoDB driver like a regular user application.
-They could test any MongoDB-compatible database (such as FerretDB or MongoDB itself) via a regular TCP or TLS port or Unix socket.
+They could test any MongoDB-compatible database (such as FerretDB or MongoDB itself) via a regular TCP or TLS port
+or Unix domain socket.
 They also could test in-process FerretDB instances
 (meaning that integration tests start and stop them themselves) with a given backend.
 Finally, some integration tests (so-called compatibility or "compat" tests) connect to two systems

ferretdb/ferretdb.go

@@ -214,7 +214,7 @@ func (f *FerretDB) MongoDBURI() string {
 			Path:   "/",
 		}
 	case f.config.Listener.Unix != "":
-		// MongoDB really wants Unix socket path in the host part of the URI
+		// MongoDB really wants Unix domain socket path in the host part of the URI
 		u = &url.URL{
 			Scheme: "mongodb",
 			Host:   f.l.UnixAddr().String(),

integration/commands_diagnostic_test.go

@@ -403,7 +403,7 @@ func TestCommandsDiagnosticWhatsMyURI(t *testing.T) {
 	databaseName := s.Collection.Database().Name()
 	collectionName := s.Collection.Name()
 
-	// only check port number on TCP connection, no need to check on Unix socket
+	// only check port number on TCP connection, no need to check on Unix domain socket
 	isUnix := s.IsUnixSocket(t)
 
 	// setup second client connection to check that `whatsmyuri` returns different ports

integration/setup/setup.go

@@ -45,7 +45,7 @@ var (
 
 	targetProxyAddrF  = flag.String("target-proxy-addr", "", "in-process FerretDB: use given proxy")
 	targetTLSF        = flag.Bool("target-tls", false, "in-process FerretDB: use TLS")
-	targetUnixSocketF = flag.Bool("target-unix-socket", false, "in-process FerretDB: use Unix socket")
+	targetUnixSocketF = flag.Bool("target-unix-socket", false, "in-process FerretDB: use Unix domain socket")
 
 	postgreSQLURLF = flag.String("postgresql-url", "", "in-process FerretDB: PostgreSQL URL for 'postgresql' handler.")
 	sqliteURLF     = flag.String("sqlite-url", "", "in-process FerretDB: SQLite URI for 'sqlite' handler.")
@@ -97,12 +97,12 @@ type SetupResult struct {
 	MongoDBURI string
 }
 
-// IsUnixSocket returns true if MongoDB URI is a Unix socket.
+// IsUnixSocket returns true if MongoDB URI is a Unix domain socket.
 func (s *SetupResult) IsUnixSocket(tb testtb.TB) bool {
 	tb.Helper()
 
 	// we can't use a regular url.Parse because
-	// MongoDB really wants Unix socket path in the host part of the URI
+	// MongoDB really wants Unix domain socket path in the host part of the URI
 	opts := options.Client().ApplyURI(s.MongoDBURI)
 	res := slices.ContainsFunc(opts.Hosts, func(host string) bool {
 		return strings.Contains(host, "/")

internal/clientconn/conn.go

@@ -24,6 +24,7 @@
 	"fmt"
 	"io"
 	"net"
+	"net/netip"
 	"os"
 	"path/filepath"
 	"runtime/pprof"
@@ -140,7 +141,10 @@
 
 	connInfo := conninfo.New()
 	if c.netConn.RemoteAddr().Network() != "unix" {
-		connInfo.PeerAddr = c.netConn.RemoteAddr().String()
+		connInfo.Peer, err = netip.ParseAddrPort(c.netConn.RemoteAddr().String())
+		if err != nil {
+			return
+		}
 	}
 
 	ctx = conninfo.Ctx(ctx, connInfo)

internal/clientconn/conninfo/conn_info.go

@@ -17,6 +17,7 @@ package conninfo
 
 import (
 	"context"
+	"net/netip"
 	"sync"
 
 	"github.com/xdg-go/scram"
@@ -32,28 +33,35 @@ var connInfoKey = contextKey{}
 type ConnInfo struct {
 	// the order of fields is weird to make the struct smaller due to alignment
 
-	PeerAddr     string
-	username     string // protected by rw
-	password     string // protected by rw
-	metadataRecv bool   // protected by rw
-
 	sc *scram.ServerConversation // protected by rw
 
+	Peer netip.AddrPort // invalid for Unix domain sockets
+
+	username string // protected by rw
+	password string // protected by rw
+
+	rw sync.RWMutex
+
+	metadataRecv bool // protected by rw
+
 	// If true, backend implementations should not perform authentication
 	// by adding username and password to the connection string.
 	// It is set to true for background connections (such us capped collections cleanup)
 	// and by the new authentication mechanism.
 	// See where it is used for more details.
 	bypassBackendAuth bool // protected by rw
-
-	rw sync.RWMutex
 }
 
 // New returns a new ConnInfo.
 func New() *ConnInfo {
 	return new(ConnInfo)
 }
 
+// LocalPeer returns whether the peer is considered local (using Unix domain socket or loopback IP).
+func (connInfo *ConnInfo) LocalPeer() bool {
+	return !connInfo.Peer.IsValid() || connInfo.Peer.Addr().IsLoopback()
+}
+
 // Username returns stored username.
 func (connInfo *ConnInfo) Username() string {
 	connInfo.rw.RLock()
@@ -89,8 +97,8 @@ func (connInfo *ConnInfo) Conv() *scram.ServerConversation {
 
 // SetConv stores the SCRAM server conversation.
 func (connInfo *ConnInfo) SetConv(sc *scram.ServerConversation) {
-	connInfo.rw.RLock()
-	defer connInfo.rw.RUnlock()
+	connInfo.rw.Lock()
+	defer connInfo.rw.Unlock()
 
 	connInfo.username = sc.Username()
 	connInfo.sc = sc

internal/clientconn/conninfo/conn_info_test.go

@@ -16,6 +16,7 @@ package conninfo
 
 import (
 	"context"
+	"net/netip"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -25,26 +26,30 @@ func TestGet(t *testing.T) {
 	t.Parallel()
 
 	for name, tc := range map[string]struct {
-		peerAddr string
+		peer  netip.AddrPort
+		local bool
 	}{
-		"EmptyPeerAddr": {
-			peerAddr: "",
+		"Unix": {
+			local: true,
 		},
-		"NonEmptyPeerAddr": {
-			peerAddr: "127.0.0.8:1234",
+		"Local": {
+			peer:  netip.MustParseAddrPort("127.42.7.1:1234"),
+			local: true,
+		},
+		"NonLocal": {
+			peer:  netip.MustParseAddrPort("192.168.0.1:1234"),
+			local: false,
 		},
 	} {
-		tc := tc
 		t.Run(name, func(t *testing.T) {
-			t.Parallel()
-
 			ctx := context.Background()
 			connInfo := &ConnInfo{
-				PeerAddr: tc.peerAddr,
+				Peer: tc.peer,
 			}
 			ctx = Ctx(ctx, connInfo)
 			actual := Get(ctx)
 			assert.Equal(t, connInfo, actual)
+			assert.Equal(t, tc.local, actual.LocalPeer())
 		})
 	}
 

internal/handler/msg_whatsmyuri.go

@@ -28,7 +28,7 @@ func (h *Handler) MsgWhatsMyURI(ctx context.Context, msg *wire.OpMsg) (*wire.OpM
 	var reply wire.OpMsg
 	must.NoError(reply.SetSections(wire.MakeOpMsgSection(
 		must.NotFail(types.NewDocument(
-			"you", conninfo.Get(ctx).PeerAddr,
+			"you", conninfo.Get(ctx).Peer.String(),
 			"ok", float64(1),
 		)),
 	)))

website/blog/2022-11-21-ferretdb-0-6-2-version-release.md

@@ -33,7 +33,7 @@ In the latest release, we have published our commands parity guide with MongoDB,
 
 ## Bug Fixes
 
-We've fixed issues with Unix socket listeners, where you get internal errors or panic when running FerretDB with a Unix socket listener.
+We've fixed issues with Unix domain socket listeners, where you get internal errors or panic when running FerretDB with a Unix domain socket listener.
 
 ## Other changes and enhancements