Contents of /tags/mkinitrd-6_4_0/busybox/libbb/udp_io.c
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Fri May 27 18:20:23 2011 UTC (13 years, 4 months ago) by niro
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File size: 5431 byte(s)
Fri May 27 18:20:23 2011 UTC (13 years, 4 months ago) by niro
File MIME type: text/plain
File size: 5431 byte(s)
tagged 'mkinitrd-6_4_0'
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Utility routines. |
4 | * |
5 | * Copyright (C) 2007 Denys Vlasenko |
6 | * |
7 | * Licensed under GPL version 2, see file LICENSE in this tarball for details. |
8 | */ |
9 | #include "libbb.h" |
10 | |
11 | /* |
12 | * This asks kernel to let us know dst addr/port of incoming packets |
13 | * We don't check for errors here. Not supported == won't be used |
14 | */ |
15 | void FAST_FUNC |
16 | socket_want_pktinfo(int fd) |
17 | { |
18 | #ifdef IP_PKTINFO |
19 | setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &const_int_1, sizeof(int)); |
20 | #endif |
21 | #if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
22 | setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, &const_int_1, sizeof(int)); |
23 | #endif |
24 | } |
25 | |
26 | |
27 | ssize_t FAST_FUNC |
28 | send_to_from(int fd, void *buf, size_t len, int flags, |
29 | const struct sockaddr *to, |
30 | const struct sockaddr *from, |
31 | socklen_t tolen) |
32 | { |
33 | #ifndef IP_PKTINFO |
34 | (void)from; /* suppress "unused from" warning */ |
35 | return sendto(fd, buf, len, flags, to, tolen); |
36 | #else |
37 | struct iovec iov[1]; |
38 | struct msghdr msg; |
39 | union { |
40 | char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))]; |
41 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
42 | char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))]; |
43 | # endif |
44 | } u; |
45 | struct cmsghdr* cmsgptr; |
46 | |
47 | if (from->sa_family != AF_INET |
48 | # if ENABLE_FEATURE_IPV6 |
49 | && from->sa_family != AF_INET6 |
50 | # endif |
51 | ) { |
52 | /* ANY local address */ |
53 | return sendto(fd, buf, len, flags, to, tolen); |
54 | } |
55 | |
56 | /* man recvmsg and man cmsg is needed to make sense of code below */ |
57 | |
58 | iov[0].iov_base = buf; |
59 | iov[0].iov_len = len; |
60 | |
61 | memset(&u, 0, sizeof(u)); |
62 | |
63 | memset(&msg, 0, sizeof(msg)); |
64 | msg.msg_name = (void *)(struct sockaddr *)to; /* or compiler will annoy us */ |
65 | msg.msg_namelen = tolen; |
66 | msg.msg_iov = iov; |
67 | msg.msg_iovlen = 1; |
68 | msg.msg_control = &u; |
69 | msg.msg_controllen = sizeof(u); |
70 | msg.msg_flags = flags; |
71 | |
72 | cmsgptr = CMSG_FIRSTHDR(&msg); |
73 | if (to->sa_family == AF_INET && from->sa_family == AF_INET) { |
74 | struct in_pktinfo *pktptr; |
75 | cmsgptr->cmsg_level = IPPROTO_IP; |
76 | cmsgptr->cmsg_type = IP_PKTINFO; |
77 | cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo)); |
78 | pktptr = (struct in_pktinfo *)(CMSG_DATA(cmsgptr)); |
79 | /*pktptr->ipi_ifindex = 0; -- already done by memset(u...) */ |
80 | /* In general, CMSG_DATA() can be unaligned, but in this case |
81 | * we know for sure it is sufficiently aligned: |
82 | * CMSG_FIRSTHDR simply returns &u above, |
83 | * and CMSG_DATA returns &u + size_t + int + int. |
84 | * Thus direct assignment is ok: |
85 | */ |
86 | pktptr->ipi_spec_dst = ((struct sockaddr_in*)from)->sin_addr; |
87 | } |
88 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
89 | else if (to->sa_family == AF_INET6 && from->sa_family == AF_INET6) { |
90 | struct in6_pktinfo *pktptr; |
91 | cmsgptr->cmsg_level = IPPROTO_IPV6; |
92 | cmsgptr->cmsg_type = IPV6_PKTINFO; |
93 | cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo)); |
94 | pktptr = (struct in6_pktinfo *)(CMSG_DATA(cmsgptr)); |
95 | /* pktptr->ipi6_ifindex = 0; -- already done by memset(u...) */ |
96 | pktptr->ipi6_addr = ((struct sockaddr_in6*)from)->sin6_addr; |
97 | } |
98 | # endif |
99 | msg.msg_controllen = cmsgptr->cmsg_len; |
100 | |
101 | return sendmsg(fd, &msg, flags); |
102 | #endif |
103 | } |
104 | |
105 | /* NB: this will never set port# in 'to'! |
106 | * _Only_ IP/IPv6 address part of 'to' is _maybe_ modified. |
107 | * Typical usage is to preinit 'to' with "default" value |
108 | * before calling recv_from_to(). */ |
109 | ssize_t FAST_FUNC |
110 | recv_from_to(int fd, void *buf, size_t len, int flags, |
111 | struct sockaddr *from, struct sockaddr *to, |
112 | socklen_t sa_size) |
113 | { |
114 | #ifndef IP_PKTINFO |
115 | (void)to; /* suppress "unused to" warning */ |
116 | return recvfrom(fd, buf, len, flags, from, &sa_size); |
117 | #else |
118 | /* man recvmsg and man cmsg is needed to make sense of code below */ |
119 | struct iovec iov[1]; |
120 | union { |
121 | char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))]; |
122 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
123 | char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))]; |
124 | # endif |
125 | } u; |
126 | struct cmsghdr *cmsgptr; |
127 | struct msghdr msg; |
128 | ssize_t recv_length; |
129 | |
130 | iov[0].iov_base = buf; |
131 | iov[0].iov_len = len; |
132 | |
133 | memset(&msg, 0, sizeof(msg)); |
134 | msg.msg_name = (struct sockaddr *)from; |
135 | msg.msg_namelen = sa_size; |
136 | msg.msg_iov = iov; |
137 | msg.msg_iovlen = 1; |
138 | msg.msg_control = &u; |
139 | msg.msg_controllen = sizeof(u); |
140 | |
141 | recv_length = recvmsg(fd, &msg, flags); |
142 | if (recv_length < 0) |
143 | return recv_length; |
144 | |
145 | # define to4 ((struct sockaddr_in*)to) |
146 | # define to6 ((struct sockaddr_in6*)to) |
147 | /* Here we try to retrieve destination IP and memorize it */ |
148 | for (cmsgptr = CMSG_FIRSTHDR(&msg); |
149 | cmsgptr != NULL; |
150 | cmsgptr = CMSG_NXTHDR(&msg, cmsgptr) |
151 | ) { |
152 | if (cmsgptr->cmsg_level == IPPROTO_IP |
153 | && cmsgptr->cmsg_type == IP_PKTINFO |
154 | ) { |
155 | const int IPI_ADDR_OFF = offsetof(struct in_pktinfo, ipi_addr); |
156 | to->sa_family = AF_INET; |
157 | /*# define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )*/ |
158 | /*to4->sin_addr = pktinfo(cmsgptr)->ipi_addr; - may be unaligned */ |
159 | memcpy(&to4->sin_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI_ADDR_OFF, sizeof(to4->sin_addr)); |
160 | /*to4->sin_port = 123; - this data is not supplied by kernel */ |
161 | break; |
162 | } |
163 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO) |
164 | if (cmsgptr->cmsg_level == IPPROTO_IPV6 |
165 | && cmsgptr->cmsg_type == IPV6_PKTINFO |
166 | ) { |
167 | const int IPI6_ADDR_OFF = offsetof(struct in6_pktinfo, ipi6_addr); |
168 | to->sa_family = AF_INET6; |
169 | /*# define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )*/ |
170 | /*to6->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; - may be unaligned */ |
171 | memcpy(&to6->sin6_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI6_ADDR_OFF, sizeof(to6->sin6_addr)); |
172 | /*to6->sin6_port = 123; */ |
173 | break; |
174 | } |
175 | # endif |
176 | } |
177 | return recv_length; |
178 | #endif |
179 | } |