ipc: pin that a scheme-less address still dials unix (V-484)

Six cases. The load-bearing one is the first: every deploy in the tree
writes a bare path, and it must keep meaning a unix socket with no
handshake in front of the payload.

The rest cover the tcp seam: a good token round-trips, a wrong one comes
back ErrUnauthorized, a stranger that speaks HTTP at the port is dropped
while the listener stays up for the next peer, and a tokenless tcp bind
fails rather than serving his turns to anyone who connects.

internal/netaddr/netaddr_test.go

@@ -0,0 +1,185 @@
+package netaddr
+
+import (
+	"errors"
+	"net"
+	"path/filepath"
+	"testing"
+)
+
+// A scheme-less address must stay unix. Every deploy in the tree writes a bare
+// path, so this is the test that says the transport change costs them nothing.
+func TestParseSchemelessIsUnix(t *testing.T) {
+	a, err := Parse("/run/maven/stt.sock")
+	if err != nil {
+		t.Fatalf("parse: %v", err)
+	}
+	if !a.IsUnix() {
+		t.Fatalf("want unix, got %q", a.Network)
+	}
+	if a.Address != "/run/maven/stt.sock" {
+		t.Fatalf("address = %q", a.Address)
+	}
+	if a.Token != "" {
+		t.Fatalf("unix seam carries a token: %q", a.Token)
+	}
+}
+
+func TestParse(t *testing.T) {
+	cases := []struct {
+		in            string
+		net, addr, tk string
+		wantErr       bool
+	}{
+		{in: "", net: "unix", addr: ""},
+		{in: "unix:///run/maven/core.sock", net: "unix", addr: "/run/maven/core.sock"},
+		{in: "tcp://workstation:9310", net: "tcp", addr: "workstation:9310"},
+		{in: "tcp://workstation:9310?token=hunter2", net: "tcp", addr: "workstation:9310", tk: "hunter2"},
+		{in: "tcp://", wantErr: true},
+		{in: "udp://workstation:9310", wantErr: true},
+	}
+	for _, c := range cases {
+		a, err := Parse(c.in)
+		if c.wantErr {
+			if err == nil {
+				t.Errorf("Parse(%q) = %v, want error", c.in, a)
+			}
+			continue
+		}
+		if err != nil {
+			t.Errorf("Parse(%q): %v", c.in, err)
+			continue
+		}
+		if a.Network != c.net || a.Address != c.addr || a.Token != c.tk {
+			t.Errorf("Parse(%q) = %+v, want %s/%s/%s", c.in, a, c.net, c.addr, c.tk)
+		}
+	}
+}
+
+// The token must never reach a log line.
+func TestStringHidesToken(t *testing.T) {
+	a := MustParse("tcp://workstation:9310?token=hunter2")
+	if got := a.String(); got != "tcp://workstation:9310" {
+		t.Fatalf("String() = %q", got)
+	}
+}
+
+// A unix seam must round-trip with no handshake in front of the payload: the
+// first bytes the listener sees are the caller's, exactly as before.
+func TestUnixRoundTripHasNoHandshake(t *testing.T) {
+	a := MustParse(filepath.Join(t.TempDir(), "s.sock"))
+	ln, err := Listen(a)
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+	defer ln.Close()
+	go echoOnce(ln)
+
+	c, err := Dial(a)
+	if err != nil {
+		t.Fatalf("dial: %v", err)
+	}
+	defer c.Close()
+	if got := roundTrip(t, c, "hello"); got != "hello" {
+		t.Fatalf("got %q", got)
+	}
+}
+
+func TestTCPRoundTripWithToken(t *testing.T) {
+	ln, addr := listenLoopback(t, "s3cret")
+	defer ln.Close()
+	go echoOnce(ln)
+
+	c, err := Dial(addr)
+	if err != nil {
+		t.Fatalf("dial: %v", err)
+	}
+	defer c.Close()
+	if got := roundTrip(t, c, "hello"); got != "hello" {
+		t.Fatalf("got %q", got)
+	}
+}
+
+func TestTCPWrongTokenIsRejected(t *testing.T) {
+	ln, addr := listenLoopback(t, "s3cret")
+	defer ln.Close()
+	// Accept keeps waiting past the bad peer, so nothing here should ever
+	// reach the echo. A conn that does means the token was not checked.
+	go echoOnce(ln)
+
+	bad := addr
+	bad.Token = "wrong"
+	if _, err := Dial(bad); !errors.Is(err, ErrUnauthorized) {
+		t.Fatalf("dial with wrong token: err = %v, want ErrUnauthorized", err)
+	}
+}
+
+// A stranger that speaks the protocol instead of the greeting is dropped, and
+// the listener stays up for the peer that follows it.
+func TestTCPUngreetedPeerDoesNotKillTheListener(t *testing.T) {
+	ln, addr := listenLoopback(t, "s3cret")
+	defer ln.Close()
+	go echoOnce(ln)
+
+	raw, err := net.Dial("tcp", addr.Address)
+	if err != nil {
+		t.Fatalf("raw dial: %v", err)
+	}
+	if _, err := raw.Write([]byte("GET / HTTP/1.1\n")); err != nil {
+		t.Fatalf("raw write: %v", err)
+	}
+	raw.Close()
+
+	c, err := Dial(addr)
+	if err != nil {
+		t.Fatalf("dial after stranger: %v", err)
+	}
+	defer c.Close()
+	if got := roundTrip(t, c, "still here"); got != "still here" {
+		t.Fatalf("got %q", got)
+	}
+}
+
+// A tcp seam with no token is a misconfiguration, and it must fail at bind
+// rather than serve the owner's turns to anyone who connects.
+func TestTCPListenRequiresToken(t *testing.T) {
+	if _, err := Listen(MustParse("tcp://127.0.0.1:0")); err == nil {
+		t.Fatal("listen on a tokenless tcp seam succeeded")
+	}
+}
+
+func listenLoopback(t *testing.T, token string) (*Listener, Addr) {
+	t.Helper()
+	ln, err := Listen(Addr{Network: "tcp", Address: "127.0.0.1:0", Token: token})
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+	return ln, Addr{Network: "tcp", Address: ln.Addr().String(), Token: token}
+}
+
+func echoOnce(ln *Listener) {
+	c, err := ln.Accept()
+	if err != nil {
+		return
+	}
+	defer c.Close()
+	buf := make([]byte, 256)
+	n, err := c.Read(buf)
+	if err != nil {
+		return
+	}
+	_, _ = c.Write(buf[:n])
+}
+
+func roundTrip(t *testing.T, c net.Conn, msg string) string {
+	t.Helper()
+	if _, err := c.Write([]byte(msg)); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	buf := make([]byte, 256)
+	n, err := c.Read(buf)
+	if err != nil {
+		t.Fatalf("read: %v", err)
+	}
+	return string(buf[:n])
+}