source: branches/3.2/mindi-busybox/libbb/udp_io.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 5 years ago
  • Update mindi-busybox to 1.21.1
  • Property svn:eol-style set to native
File size: 5.3 KB
Line 
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/*
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 */
15void FAST_FUNC
16socket_want_pktinfo(int fd UNUSED_PARAM)
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
27ssize_t FAST_FUNC
28send_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(). */
109ssize_t FAST_FUNC
110recv_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}
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