unix: implement AF_TIPC sockets on Linux

Adds initial constants and types to use with SockaddrTIPC. For more
information on TIPC, see: http://tipc.sourceforge.net/.

Because the C struct sockaddr_tipc makes use of a union for its addr
field, I have created a wrapping layer in SockaddrTIPC that uses
an interface to determine which variant is in use.

Tests accompany this change due to the complexity of this code. There
is currently little test coverage in the Sockaddr-related code, but
perhaps this is something that could be picked up as a relatively
straightforward task for a new contributor.

Change-Id: I5033a0685cb7128d4b1a23d18aca71c202d0c0aa
Reviewed-on: https://go-review.googlesource.com/c/sys/+/187960
Run-TryBot: Matt Layher <mdlayher@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

unix/syscall_internal_linux_test.go

@@ -0,0 +1,216 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build linux
+
+package unix
+
+import (
+	"reflect"
+	"testing"
+	"unsafe"
+)
+
+func Test_anyToSockaddr(t *testing.T) {
+	tests := []struct {
+		name string
+		rsa  *RawSockaddrAny
+		sa   Sockaddr
+		err  error
+	}{
+		{
+			name: "AF_TIPC bad addrtype",
+			rsa: &RawSockaddrAny{
+				Addr: RawSockaddr{
+					Family: AF_TIPC,
+				},
+			},
+			err: EINVAL,
+		},
+		{
+			name: "AF_TIPC NameSeq",
+			rsa: (*RawSockaddrAny)(unsafe.Pointer(&RawSockaddrTIPC{
+				Family:   AF_TIPC,
+				Addrtype: TIPC_SERVICE_RANGE,
+				Scope:    1,
+				Addr: (&TIPCServiceRange{
+					Type:  1,
+					Lower: 2,
+					Upper: 3,
+				}).tipcAddr(),
+			})),
+			sa: &SockaddrTIPC{
+				Scope: 1,
+				Addr: &TIPCServiceRange{
+					Type:  1,
+					Lower: 2,
+					Upper: 3,
+				},
+			},
+		},
+		{
+			name: "AF_TIPC Name",
+			rsa: (*RawSockaddrAny)(unsafe.Pointer(&RawSockaddrTIPC{
+				Family:   AF_TIPC,
+				Addrtype: TIPC_SERVICE_ADDR,
+				Scope:    2,
+				Addr: (&TIPCServiceName{
+					Type:     1,
+					Instance: 2,
+					Domain:   3,
+				}).tipcAddr(),
+			})),
+			sa: &SockaddrTIPC{
+				Scope: 2,
+				Addr: &TIPCServiceName{
+					Type:     1,
+					Instance: 2,
+					Domain:   3,
+				},
+			},
+		},
+		{
+			name: "AF_TIPC ID",
+			rsa: (*RawSockaddrAny)(unsafe.Pointer(&RawSockaddrTIPC{
+				Family:   AF_TIPC,
+				Addrtype: TIPC_SOCKET_ADDR,
+				Scope:    3,
+				Addr: (&TIPCSocketAddr{
+					Ref:  1,
+					Node: 2,
+				}).tipcAddr(),
+			})),
+			sa: &SockaddrTIPC{
+				Scope: 3,
+				Addr: &TIPCSocketAddr{
+					Ref:  1,
+					Node: 2,
+				},
+			},
+		},
+		{
+			name: "AF_MAX EAFNOSUPPORT",
+			rsa: &RawSockaddrAny{
+				Addr: RawSockaddr{
+					Family: AF_MAX,
+				},
+			},
+			err: EAFNOSUPPORT,
+		},
+		// TODO: expand to support other families.
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: parameterize fd (and its setup) when needed.
+			sa, err := anyToSockaddr(0, tt.rsa)
+			if err != tt.err {
+				t.Fatalf("unexpected error: %v, want: %v", err, tt.err)
+			}
+
+			if !reflect.DeepEqual(sa, tt.sa) {
+				t.Fatalf("unexpected Sockaddr:\n got: %#v\nwant: %#v", sa, tt.sa)
+			}
+		})
+	}
+}
+
+func TestSockaddrTIPC_sockaddr(t *testing.T) {
+	tests := []struct {
+		name string
+		sa   *SockaddrTIPC
+		raw  *RawSockaddrTIPC
+		err  error
+	}{
+		{
+			name: "no fields set",
+			sa:   &SockaddrTIPC{},
+			err:  EINVAL,
+		},
+		{
+			name: "ID",
+			sa: &SockaddrTIPC{
+				Scope: 1,
+				Addr: &TIPCSocketAddr{
+					Ref:  1,
+					Node: 2,
+				},
+			},
+			raw: &RawSockaddrTIPC{
+				Family:   AF_TIPC,
+				Addrtype: TIPC_SOCKET_ADDR,
+				Scope:    1,
+				Addr: (&TIPCSocketAddr{
+					Ref:  1,
+					Node: 2,
+				}).tipcAddr(),
+			},
+		},
+		{
+			name: "NameSeq",
+			sa: &SockaddrTIPC{
+				Scope: 2,
+				Addr: &TIPCServiceRange{
+					Type:  1,
+					Lower: 2,
+					Upper: 3,
+				},
+			},
+			raw: &RawSockaddrTIPC{
+				Family:   AF_TIPC,
+				Addrtype: TIPC_SERVICE_RANGE,
+				Scope:    2,
+				Addr: (&TIPCServiceRange{
+					Type:  1,
+					Lower: 2,
+					Upper: 3,
+				}).tipcAddr(),
+			},
+		},
+		{
+			name: "Name",
+			sa: &SockaddrTIPC{
+				Scope: 3,
+				Addr: &TIPCServiceName{
+					Type:     1,
+					Instance: 2,
+					Domain:   3,
+				},
+			},
+			raw: &RawSockaddrTIPC{
+				Family:   AF_TIPC,
+				Addrtype: TIPC_SERVICE_ADDR,
+				Scope:    3,
+				Addr: (&TIPCServiceName{
+					Type:     1,
+					Instance: 2,
+					Domain:   3,
+				}).tipcAddr(),
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			out, l, err := tt.sa.sockaddr()
+			if err != tt.err {
+				t.Fatalf("unexpected error: %v, want: %v", err, tt.err)
+			}
+
+			// Must be 0 on error or a fixed size otherwise.
+			if (tt.err != nil && l != 0) || (tt.raw != nil && l != SizeofSockaddrTIPC) {
+				t.Fatalf("unexpected Socklen: %d", l)
+			}
+			if out == nil {
+				// No pointer to cast, return early.
+				return
+			}
+
+			raw := (*RawSockaddrTIPC)(out)
+			if !reflect.DeepEqual(raw, tt.raw) {
+				t.Fatalf("unexpected RawSockaddrTIPC:\n got: %#v\nwant: %#v", raw, tt.raw)
+			}
+		})
+	}
+}