blob: d37a73ba466951f18dc4ee072c8214ee580d1692
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Utility routines. |
4 | * |
5 | * Copyright (C) 2007 Denys Vlasenko |
6 | * |
7 | * Licensed under GPLv2, see file LICENSE in this source tree. |
8 | */ |
9 | #include "libbb.h" |
10 | |
11 | #if defined(IPV6_PKTINFO) && defined(__BIONIC__) && !defined(BIONIC_ICS) |
12 | // now included in Bionic ICS |
13 | struct in6_pktinfo { |
14 | struct in6_addr ipi6_addr; // src/dst IPv6 address |
15 | unsigned int ipi6_ifindex; // send/recv if index |
16 | }; |
17 | #endif |
18 | |
19 | /* |
20 | * This asks kernel to let us know dst addr/port of incoming packets |
21 | * We don't check for errors here. Not supported == won't be used |
22 | */ |
23 | void FAST_FUNC |
24 | socket_want_pktinfo(int fd UNUSED_PARAM) |
25 | { |
26 | #ifdef IP_PKTINFO |
27 | setsockopt_1(fd, IPPROTO_IP, IP_PKTINFO); |
28 | #endif |
29 | #if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
30 | setsockopt_1(fd, IPPROTO_IPV6, IPV6_PKTINFO); |
31 | #endif |
32 | } |
33 | |
34 | |
35 | ssize_t FAST_FUNC |
36 | send_to_from(int fd, void *buf, size_t len, int flags, |
37 | const struct sockaddr *to, |
38 | const struct sockaddr *from, |
39 | socklen_t tolen) |
40 | { |
41 | #ifndef IP_PKTINFO |
42 | (void)from; /* suppress "unused from" warning */ |
43 | return sendto(fd, buf, len, flags, to, tolen); |
44 | #else |
45 | struct iovec iov[1]; |
46 | struct msghdr msg; |
47 | union { |
48 | char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))]; |
49 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
50 | char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))]; |
51 | # endif |
52 | } u; |
53 | struct cmsghdr* cmsgptr; |
54 | |
55 | if (from->sa_family != AF_INET |
56 | # if ENABLE_FEATURE_IPV6 |
57 | && from->sa_family != AF_INET6 |
58 | # endif |
59 | ) { |
60 | /* ANY local address */ |
61 | return sendto(fd, buf, len, flags, to, tolen); |
62 | } |
63 | |
64 | /* man recvmsg and man cmsg is needed to make sense of code below */ |
65 | |
66 | iov[0].iov_base = buf; |
67 | iov[0].iov_len = len; |
68 | |
69 | memset(&u, 0, sizeof(u)); |
70 | |
71 | memset(&msg, 0, sizeof(msg)); |
72 | msg.msg_name = (void *)(struct sockaddr *)to; /* or compiler will annoy us */ |
73 | msg.msg_namelen = tolen; |
74 | msg.msg_iov = iov; |
75 | msg.msg_iovlen = 1; |
76 | msg.msg_control = &u; |
77 | msg.msg_controllen = sizeof(u); |
78 | msg.msg_flags = flags; |
79 | |
80 | cmsgptr = CMSG_FIRSTHDR(&msg); |
81 | /* |
82 | * Users report that to->sa_family can be AF_INET6 too, |
83 | * if "to" was acquired by recv_from_to(). IOW: recv_from_to() |
84 | * was seen showing IPv6 "from" even when the destination |
85 | * of received packet (our local address) was IPv4. |
86 | */ |
87 | if (/* to->sa_family == AF_INET && */ from->sa_family == AF_INET) { |
88 | struct in_pktinfo *pktptr; |
89 | cmsgptr->cmsg_level = IPPROTO_IP; |
90 | cmsgptr->cmsg_type = IP_PKTINFO; |
91 | cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo)); |
92 | pktptr = (struct in_pktinfo *)(CMSG_DATA(cmsgptr)); |
93 | /*pktptr->ipi_ifindex = 0; -- already done by memset(u...) */ |
94 | /* In general, CMSG_DATA() can be unaligned, but in this case |
95 | * we know for sure it is sufficiently aligned: |
96 | * CMSG_FIRSTHDR simply returns &u above, |
97 | * and CMSG_DATA returns &u + size_t + int + int. |
98 | * Thus direct assignment is ok: |
99 | */ |
100 | pktptr->ipi_spec_dst = ((struct sockaddr_in*)from)->sin_addr; |
101 | } |
102 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
103 | else if (/* to->sa_family == AF_INET6 && */ from->sa_family == AF_INET6) { |
104 | struct in6_pktinfo *pktptr; |
105 | cmsgptr->cmsg_level = IPPROTO_IPV6; |
106 | cmsgptr->cmsg_type = IPV6_PKTINFO; |
107 | cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo)); |
108 | pktptr = (struct in6_pktinfo *)(CMSG_DATA(cmsgptr)); |
109 | /* pktptr->ipi6_ifindex = 0; -- already done by memset(u...) */ |
110 | pktptr->ipi6_addr = ((struct sockaddr_in6*)from)->sin6_addr; |
111 | } |
112 | # endif |
113 | msg.msg_controllen = cmsgptr->cmsg_len; |
114 | |
115 | return sendmsg(fd, &msg, flags); |
116 | #endif |
117 | } |
118 | |
119 | /* NB: this will never set port# in 'to'! |
120 | * _Only_ IP/IPv6 address part of 'to' is _maybe_ modified. |
121 | * Typical usage is to preinit 'to' with "default" value |
122 | * before calling recv_from_to(). */ |
123 | ssize_t FAST_FUNC |
124 | recv_from_to(int fd, void *buf, size_t len, int flags, |
125 | struct sockaddr *from, struct sockaddr *to, |
126 | socklen_t sa_size) |
127 | { |
128 | #ifndef IP_PKTINFO |
129 | (void)to; /* suppress "unused to" warning */ |
130 | return recvfrom(fd, buf, len, flags, from, &sa_size); |
131 | #else |
132 | /* man recvmsg and man cmsg is needed to make sense of code below */ |
133 | struct iovec iov[1]; |
134 | union { |
135 | char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))]; |
136 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
137 | char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))]; |
138 | # endif |
139 | } u; |
140 | struct cmsghdr *cmsgptr; |
141 | struct msghdr msg; |
142 | ssize_t recv_length; |
143 | |
144 | iov[0].iov_base = buf; |
145 | iov[0].iov_len = len; |
146 | |
147 | memset(&msg, 0, sizeof(msg)); |
148 | msg.msg_name = (struct sockaddr *)from; |
149 | msg.msg_namelen = sa_size; |
150 | msg.msg_iov = iov; |
151 | msg.msg_iovlen = 1; |
152 | msg.msg_control = &u; |
153 | msg.msg_controllen = sizeof(u); |
154 | |
155 | recv_length = recvmsg(fd, &msg, flags); |
156 | if (recv_length < 0) |
157 | return recv_length; |
158 | |
159 | # define to4 ((struct sockaddr_in*)to) |
160 | # define to6 ((struct sockaddr_in6*)to) |
161 | /* Here we try to retrieve destination IP and memorize it */ |
162 | for (cmsgptr = CMSG_FIRSTHDR(&msg); |
163 | cmsgptr != NULL; |
164 | cmsgptr = CMSG_NXTHDR(&msg, cmsgptr) |
165 | ) { |
166 | if (cmsgptr->cmsg_level == IPPROTO_IP |
167 | && cmsgptr->cmsg_type == IP_PKTINFO |
168 | ) { |
169 | const int IPI_ADDR_OFF = offsetof(struct in_pktinfo, ipi_addr); |
170 | to->sa_family = AF_INET; |
171 | /*# define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )*/ |
172 | /*to4->sin_addr = pktinfo(cmsgptr)->ipi_addr; - may be unaligned */ |
173 | memcpy(&to4->sin_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI_ADDR_OFF, sizeof(to4->sin_addr)); |
174 | /*to4->sin_port = 123; - this data is not supplied by kernel */ |
175 | break; |
176 | } |
177 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
178 | if (cmsgptr->cmsg_level == IPPROTO_IPV6 |
179 | && cmsgptr->cmsg_type == IPV6_PKTINFO |
180 | ) { |
181 | const int IPI6_ADDR_OFF = offsetof(struct in6_pktinfo, ipi6_addr); |
182 | to->sa_family = AF_INET6; |
183 | /*# define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )*/ |
184 | /*to6->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; - may be unaligned */ |
185 | memcpy(&to6->sin6_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI6_ADDR_OFF, sizeof(to6->sin6_addr)); |
186 | /*to6->sin6_port = 123; */ |
187 | break; |
188 | } |
189 | # endif |
190 | } |
191 | return recv_length; |
192 | #endif |
193 | } |
194 |