1// Copyright 2011 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package net
6
7import (
8	"os"
9	"syscall"
10	"unsafe"
11)
12
13// If the ifindex is zero, interfaceTable returns mappings of all
14// network interfaces. Otherwise it returns a mapping of a specific
15// interface.
16func interfaceTable(ifindex int) ([]Interface, error) {
17	tab, err := syscall.NetlinkRIB(syscall.RTM_GETLINK, syscall.AF_UNSPEC)
18	if err != nil {
19		return nil, os.NewSyscallError("netlinkrib", err)
20	}
21	msgs, err := syscall.ParseNetlinkMessage(tab)
22	if err != nil {
23		return nil, os.NewSyscallError("parsenetlinkmessage", err)
24	}
25	var ift []Interface
26loop:
27	for _, m := range msgs {
28		switch m.Header.Type {
29		case syscall.NLMSG_DONE:
30			break loop
31		case syscall.RTM_NEWLINK:
32			ifim := (*syscall.IfInfomsg)(unsafe.Pointer(&m.Data[0]))
33			if ifindex == 0 || ifindex == int(ifim.Index) {
34				attrs, err := syscall.ParseNetlinkRouteAttr(&m)
35				if err != nil {
36					return nil, os.NewSyscallError("parsenetlinkrouteattr", err)
37				}
38				ift = append(ift, *newLink(ifim, attrs))
39				if ifindex == int(ifim.Index) {
40					break loop
41				}
42			}
43		}
44	}
45	return ift, nil
46}
47
48const (
49	// See linux/if_arp.h.
50	// Note that Linux doesn't support IPv4 over IPv6 tunneling.
51	sysARPHardwareIPv4IPv4 = 768 // IPv4 over IPv4 tunneling
52	sysARPHardwareIPv6IPv6 = 769 // IPv6 over IPv6 tunneling
53	sysARPHardwareIPv6IPv4 = 776 // IPv6 over IPv4 tunneling
54	sysARPHardwareGREIPv4  = 778 // any over GRE over IPv4 tunneling
55	sysARPHardwareGREIPv6  = 823 // any over GRE over IPv6 tunneling
56)
57
58func newLink(ifim *syscall.IfInfomsg, attrs []syscall.NetlinkRouteAttr) *Interface {
59	ifi := &Interface{Index: int(ifim.Index), Flags: linkFlags(ifim.Flags)}
60	for _, a := range attrs {
61		switch a.Attr.Type {
62		case syscall.IFLA_ADDRESS:
63			// We never return any /32 or /128 IP address
64			// prefix on any IP tunnel interface as the
65			// hardware address.
66			switch len(a.Value) {
67			case IPv4len:
68				switch ifim.Type {
69				case sysARPHardwareIPv4IPv4, sysARPHardwareGREIPv4, sysARPHardwareIPv6IPv4:
70					continue
71				}
72			case IPv6len:
73				switch ifim.Type {
74				case sysARPHardwareIPv6IPv6, sysARPHardwareGREIPv6:
75					continue
76				}
77			}
78			var nonzero bool
79			for _, b := range a.Value {
80				if b != 0 {
81					nonzero = true
82					break
83				}
84			}
85			if nonzero {
86				ifi.HardwareAddr = a.Value[:]
87			}
88		case syscall.IFLA_IFNAME:
89			ifi.Name = string(a.Value[:len(a.Value)-1])
90		case syscall.IFLA_MTU:
91			ifi.MTU = int(*(*uint32)(unsafe.Pointer(&a.Value[:4][0])))
92		}
93	}
94	return ifi
95}
96
97func linkFlags(rawFlags uint32) Flags {
98	var f Flags
99	if rawFlags&syscall.IFF_UP != 0 {
100		f |= FlagUp
101	}
102	if rawFlags&syscall.IFF_BROADCAST != 0 {
103		f |= FlagBroadcast
104	}
105	if rawFlags&syscall.IFF_LOOPBACK != 0 {
106		f |= FlagLoopback
107	}
108	if rawFlags&syscall.IFF_POINTOPOINT != 0 {
109		f |= FlagPointToPoint
110	}
111	if rawFlags&syscall.IFF_MULTICAST != 0 {
112		f |= FlagMulticast
113	}
114	return f
115}
116
117// If the ifi is nil, interfaceAddrTable returns addresses for all
118// network interfaces. Otherwise it returns addresses for a specific
119// interface.
120func interfaceAddrTable(ifi *Interface) ([]Addr, error) {
121	tab, err := syscall.NetlinkRIB(syscall.RTM_GETADDR, syscall.AF_UNSPEC)
122	if err != nil {
123		return nil, os.NewSyscallError("netlinkrib", err)
124	}
125	msgs, err := syscall.ParseNetlinkMessage(tab)
126	if err != nil {
127		return nil, os.NewSyscallError("parsenetlinkmessage", err)
128	}
129	var ift []Interface
130	if ifi == nil {
131		var err error
132		ift, err = interfaceTable(0)
133		if err != nil {
134			return nil, err
135		}
136	}
137	ifat, err := addrTable(ift, ifi, msgs)
138	if err != nil {
139		return nil, err
140	}
141	return ifat, nil
142}
143
144func addrTable(ift []Interface, ifi *Interface, msgs []syscall.NetlinkMessage) ([]Addr, error) {
145	var ifat []Addr
146loop:
147	for _, m := range msgs {
148		switch m.Header.Type {
149		case syscall.NLMSG_DONE:
150			break loop
151		case syscall.RTM_NEWADDR:
152			ifam := (*syscall.IfAddrmsg)(unsafe.Pointer(&m.Data[0]))
153			if len(ift) != 0 || ifi.Index == int(ifam.Index) {
154				if len(ift) != 0 {
155					var err error
156					ifi, err = interfaceByIndex(ift, int(ifam.Index))
157					if err != nil {
158						return nil, err
159					}
160				}
161				attrs, err := syscall.ParseNetlinkRouteAttr(&m)
162				if err != nil {
163					return nil, os.NewSyscallError("parsenetlinkrouteattr", err)
164				}
165				ifa := newAddr(ifam, attrs)
166				if ifa != nil {
167					ifat = append(ifat, ifa)
168				}
169			}
170		}
171	}
172	return ifat, nil
173}
174
175func newAddr(ifam *syscall.IfAddrmsg, attrs []syscall.NetlinkRouteAttr) Addr {
176	var ipPointToPoint bool
177	// Seems like we need to make sure whether the IP interface
178	// stack consists of IP point-to-point numbered or unnumbered
179	// addressing.
180	for _, a := range attrs {
181		if a.Attr.Type == syscall.IFA_LOCAL {
182			ipPointToPoint = true
183			break
184		}
185	}
186	for _, a := range attrs {
187		if ipPointToPoint && a.Attr.Type == syscall.IFA_ADDRESS {
188			continue
189		}
190		switch ifam.Family {
191		case syscall.AF_INET:
192			return &IPNet{IP: IPv4(a.Value[0], a.Value[1], a.Value[2], a.Value[3]), Mask: CIDRMask(int(ifam.Prefixlen), 8*IPv4len)}
193		case syscall.AF_INET6:
194			ifa := &IPNet{IP: make(IP, IPv6len), Mask: CIDRMask(int(ifam.Prefixlen), 8*IPv6len)}
195			copy(ifa.IP, a.Value[:])
196			return ifa
197		}
198	}
199	return nil
200}
201
202// interfaceMulticastAddrTable returns addresses for a specific
203// interface.
204func interfaceMulticastAddrTable(ifi *Interface) ([]Addr, error) {
205	ifmat4 := parseProcNetIGMP("/proc/net/igmp", ifi)
206	ifmat6 := parseProcNetIGMP6("/proc/net/igmp6", ifi)
207	return append(ifmat4, ifmat6...), nil
208}
209
210func parseProcNetIGMP(path string, ifi *Interface) []Addr {
211	fd, err := open(path)
212	if err != nil {
213		return nil
214	}
215	defer fd.close()
216	var (
217		ifmat []Addr
218		name  string
219	)
220	fd.readLine() // skip first line
221	b := make([]byte, IPv4len)
222	for l, ok := fd.readLine(); ok; l, ok = fd.readLine() {
223		f := splitAtBytes(l, " :\r\t\n")
224		if len(f) < 4 {
225			continue
226		}
227		switch {
228		case l[0] != ' ' && l[0] != '\t': // new interface line
229			name = f[1]
230		case len(f[0]) == 8:
231			if ifi == nil || name == ifi.Name {
232				// The Linux kernel puts the IP
233				// address in /proc/net/igmp in native
234				// endianness.
235				for i := 0; i+1 < len(f[0]); i += 2 {
236					b[i/2], _ = xtoi2(f[0][i:i+2], 0)
237				}
238				i := *(*uint32)(unsafe.Pointer(&b[:4][0]))
239				ifma := &IPAddr{IP: IPv4(byte(i>>24), byte(i>>16), byte(i>>8), byte(i))}
240				ifmat = append(ifmat, ifma)
241			}
242		}
243	}
244	return ifmat
245}
246
247func parseProcNetIGMP6(path string, ifi *Interface) []Addr {
248	fd, err := open(path)
249	if err != nil {
250		return nil
251	}
252	defer fd.close()
253	var ifmat []Addr
254	b := make([]byte, IPv6len)
255	for l, ok := fd.readLine(); ok; l, ok = fd.readLine() {
256		f := splitAtBytes(l, " \r\t\n")
257		if len(f) < 6 {
258			continue
259		}
260		if ifi == nil || f[1] == ifi.Name {
261			for i := 0; i+1 < len(f[2]); i += 2 {
262				b[i/2], _ = xtoi2(f[2][i:i+2], 0)
263			}
264			ifma := &IPAddr{IP: IP{b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7], b[8], b[9], b[10], b[11], b[12], b[13], b[14], b[15]}}
265			ifmat = append(ifmat, ifma)
266		}
267	}
268	return ifmat
269}
270