route: fix address parsing of messages on Darwin

sizeofSockaddrInet is 16, but first byte of sockaddr specifies actual size of sockaddr. Although, 16 works for most cases, it fails for Netmasks addresses. On Darwin only the significant bits of the netmask are in the msg. Take this route message as an example ``` // rt_msg_hdr 88 00 05 01 00 00 00 00 41 08 00 00 07 00 00 00 92 7b 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // metrics 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 // SOCKADDRS - DST (100.113.0.0) 10 02 00 00 64 71 00 00 00 00 00 00 00 00 00 00 // GW utun4319 14 12 21 00 01 08 00 00 75 74 75 6e 34 33 31 39 00 00 00 00 // NETMASK 255.255.0.0 06 02 00 00 ff ff // NULL 00 00 ``` i.e. ipv4 ``` 06 02 00 00 ff ff ``` The above byte sequence is for a sockaddr that is 6 bytes long representing an ipv4 for address that is 255.255.0.0. i.e. ipv6 netmask ``` 0e 1e 00 00 00 00 00 00 ff ff ff ff ff ff 00 00 ``` The above is `/48` netmask that should also be parsed using `b[0]` of the sockaddr that contains the length. Confirmed by using `route monitor`. sources: https://github.com/apple/darwin-xnu/blob/main/bsd/net/route.h https://github.com/apple/darwin-xnu/blob/main/bsd/sys/socket.h#L603 Fixes golang/go#44740 Change-Id: I8153130d02d0a5e547fbf60a85762d3889e1d08c GitHub-Last-Rev: f7b9253 GitHub-Pull-Request: #220 Reviewed-on: https://go-review.googlesource.com/c/net/+/609577 LUCI-TryBot-Result: Go LUCI <[email protected]> Reviewed-by: Ian Lance Taylor <[email protected]> Reviewed-by: Dmitri Shuralyov <[email protected]> Auto-Submit: Ian Lance Taylor <[email protected]>
golang · Sep 6, 2024 · 3c333c0 · 3c333c0
1 parent 35b4aba
commit 3c333c0
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Showing 2 changed files with 76 additions and 5 deletions.
diff --git a/route/address.go b/route/address.go
@@ -170,20 +170,37 @@ func (a *Inet6Addr) marshal(b []byte) (int, error) {
 
 // parseInetAddr parses b as an internet address for IPv4 or IPv6.
 func parseInetAddr(af int, b []byte) (Addr, error) {
+	const (
+		off4 = 4 // offset of in_addr
+		off6 = 8 // offset of in6_addr
+	)
 	switch af {
 	case syscall.AF_INET:
-		if len(b) < sizeofSockaddrInet {
+		if len(b) < (off4+1) || len(b) < int(b[0]) {
 			return nil, errInvalidAddr
 		}
+		sockAddrLen := int(b[0])
 		a := &Inet4Addr{}
-		copy(a.IP[:], b[4:8])
+		n := off4 + 4
+		if sockAddrLen < n {
+			n = sockAddrLen
+		}
+		copy(a.IP[:], b[off4:n])
 		return a, nil
 	case syscall.AF_INET6:
-		if len(b) < sizeofSockaddrInet6 {
+		if len(b) < (off6+1) || len(b) < int(b[0]) {
 			return nil, errInvalidAddr
 		}
-		a := &Inet6Addr{ZoneID: int(nativeEndian.Uint32(b[24:28]))}
-		copy(a.IP[:], b[8:24])
+		sockAddrLen := int(b[0])
+		n := off6 + 16
+		if sockAddrLen < n {
+			n = sockAddrLen
+		}
+		a := &Inet6Addr{}
+		if sockAddrLen == sizeofSockaddrInet6 {
+			a.ZoneID = int(nativeEndian.Uint32(b[24:28]))
+		}
+		copy(a.IP[:], b[off6:n])
 		if a.IP[0] == 0xfe && a.IP[1]&0xc0 == 0x80 || a.IP[0] == 0xff && (a.IP[1]&0x0f == 0x01 || a.IP[1]&0x0f == 0x02) {
 			// KAME based IPv6 protocol stack usually
 			// embeds the interface index in the

diff --git a/route/address_darwin_test.go b/route/address_darwin_test.go
@@ -42,6 +42,60 @@ var parseAddrsOnDarwinLittleEndianTests = []parseAddrsOnDarwinTest{
 			nil,
 		},
 	},
+	{
+		syscall.RTA_DST | syscall.RTA_GATEWAY | syscall.RTA_NETMASK,
+		parseKernelInetAddr,
+		[]byte{
+			0x10, 0x02, 0x00, 0x00, 0x64, 0x71, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+
+			0x14, 0x12, 0x21, 0x00, 0x01, 0x08, 0x00, 0x00,
+			0x75, 0x74, 0x75, 0x6e, 0x34, 0x33, 0x31, 0x39,
+			0x00, 0x00, 0x00, 0x00,
+
+			0x06, 0x02, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00,
+		},
+		[]Addr{
+			&Inet4Addr{IP: [4]byte{100, 113, 0, 0}},
+			&LinkAddr{Index: 33, Name: "utun4319"},
+			&Inet4Addr{IP: [4]byte{255, 255, 0, 0}},
+			nil,
+			nil,
+			nil,
+			nil,
+			nil,
+		},
+	},
+	// route -n add -inet6 fd84:1b4e:6281:: -prefixlen 48 fe80::f22f:4bff:fe09:3bff%utun4319
+	// gw fe80:0000:0000:0000:f22f:4bff:fe09:3bff
+	{
+		syscall.RTA_DST | syscall.RTA_GATEWAY | syscall.RTA_NETMASK,
+		parseKernelInetAddr,
+		[]byte{
+			0x1c, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0xfd, 0x84, 0x1b, 0x4e, 0x62, 0x81, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00,
+
+			0x1c, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0xfe, 0x80, 0x00, 0x21, 0x00, 0x00, 0x00, 0x00,
+			0xf2, 0x2f, 0x4b, 0xff, 0xfe, 0x09, 0x3b, 0xff,
+			0x00, 0x00, 0x00, 0x00,
+
+			0x0e, 0x1e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+			0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00,
+		},
+		[]Addr{
+			&Inet6Addr{IP: [16]byte{ 0xfd, 0x84, 0x1b, 0x4e, 0x62, 0x81 }},
+			&Inet6Addr{IP: [16]byte{ 0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf2, 0x2f, 0x4b, 0xff, 0xfe, 0x09, 0x3b, 0xff }, ZoneID: 33},
+			&Inet6Addr{IP: [16]byte{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,}},
+			nil,
+			nil,
+			nil,
+			nil,
+			nil,
+		},
+	},
 }
 
 func TestParseAddrsOnDarwin(t *testing.T) {