[3320] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Utility routines.
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| 4 | *
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| 5 | * Copyright (C) 2007 Denys Vlasenko
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| 6 | *
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| 7 | * Licensed under GPLv2, see file LICENSE in this source tree.
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| 8 | */
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| 9 | #include "libbb.h"
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| 10 |
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| 11 | /*
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| 12 | * This asks kernel to let us know dst addr/port of incoming packets
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| 13 | * We don't check for errors here. Not supported == won't be used
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| 14 | */
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| 15 | void FAST_FUNC
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| 16 | socket_want_pktinfo(int fd)
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| 17 | {
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| 18 | #ifdef IP_PKTINFO
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| 19 | setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &const_int_1, sizeof(int));
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| 20 | #endif
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| 21 | #if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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| 22 | setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, &const_int_1, sizeof(int));
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| 23 | #endif
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| 24 | }
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| 25 |
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| 26 |
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| 27 | ssize_t FAST_FUNC
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| 28 | send_to_from(int fd, void *buf, size_t len, int flags,
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| 29 | const struct sockaddr *to,
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| 30 | const struct sockaddr *from,
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| 31 | socklen_t tolen)
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| 32 | {
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| 33 | #ifndef IP_PKTINFO
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| 34 | (void)from; /* suppress "unused from" warning */
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| 35 | return sendto(fd, buf, len, flags, to, tolen);
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| 36 | #else
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| 37 | struct iovec iov[1];
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| 38 | struct msghdr msg;
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| 39 | union {
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| 40 | char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
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| 41 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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| 42 | char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
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| 43 | # endif
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| 44 | } u;
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| 45 | struct cmsghdr* cmsgptr;
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| 46 |
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| 47 | if (from->sa_family != AF_INET
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| 48 | # if ENABLE_FEATURE_IPV6
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| 49 | && from->sa_family != AF_INET6
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| 50 | # endif
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| 51 | ) {
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| 52 | /* ANY local address */
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| 53 | return sendto(fd, buf, len, flags, to, tolen);
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| 54 | }
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| 55 |
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| 56 | /* man recvmsg and man cmsg is needed to make sense of code below */
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| 57 |
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| 58 | iov[0].iov_base = buf;
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| 59 | iov[0].iov_len = len;
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| 60 |
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| 61 | memset(&u, 0, sizeof(u));
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| 62 |
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| 63 | memset(&msg, 0, sizeof(msg));
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| 64 | msg.msg_name = (void *)(struct sockaddr *)to; /* or compiler will annoy us */
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| 65 | msg.msg_namelen = tolen;
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| 66 | msg.msg_iov = iov;
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| 67 | msg.msg_iovlen = 1;
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| 68 | msg.msg_control = &u;
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| 69 | msg.msg_controllen = sizeof(u);
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| 70 | msg.msg_flags = flags;
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| 71 |
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| 72 | cmsgptr = CMSG_FIRSTHDR(&msg);
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| 73 | if (to->sa_family == AF_INET && from->sa_family == AF_INET) {
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| 74 | struct in_pktinfo *pktptr;
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| 75 | cmsgptr->cmsg_level = IPPROTO_IP;
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| 76 | cmsgptr->cmsg_type = IP_PKTINFO;
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| 77 | cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
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| 78 | pktptr = (struct in_pktinfo *)(CMSG_DATA(cmsgptr));
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| 79 | /*pktptr->ipi_ifindex = 0; -- already done by memset(u...) */
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| 80 | /* In general, CMSG_DATA() can be unaligned, but in this case
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| 81 | * we know for sure it is sufficiently aligned:
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| 82 | * CMSG_FIRSTHDR simply returns &u above,
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| 83 | * and CMSG_DATA returns &u + size_t + int + int.
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| 84 | * Thus direct assignment is ok:
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| 85 | */
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| 86 | pktptr->ipi_spec_dst = ((struct sockaddr_in*)from)->sin_addr;
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| 87 | }
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| 88 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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| 89 | else if (to->sa_family == AF_INET6 && from->sa_family == AF_INET6) {
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| 90 | struct in6_pktinfo *pktptr;
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| 91 | cmsgptr->cmsg_level = IPPROTO_IPV6;
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| 92 | cmsgptr->cmsg_type = IPV6_PKTINFO;
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| 93 | cmsgptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
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| 94 | pktptr = (struct in6_pktinfo *)(CMSG_DATA(cmsgptr));
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| 95 | /* pktptr->ipi6_ifindex = 0; -- already done by memset(u...) */
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| 96 | pktptr->ipi6_addr = ((struct sockaddr_in6*)from)->sin6_addr;
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| 97 | }
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| 98 | # endif
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| 99 | msg.msg_controllen = cmsgptr->cmsg_len;
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| 100 |
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| 101 | return sendmsg(fd, &msg, flags);
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| 102 | #endif
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| 103 | }
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| 104 |
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| 105 | /* NB: this will never set port# in 'to'!
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| 106 | * _Only_ IP/IPv6 address part of 'to' is _maybe_ modified.
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| 107 | * Typical usage is to preinit 'to' with "default" value
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| 108 | * before calling recv_from_to(). */
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| 109 | ssize_t FAST_FUNC
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| 110 | recv_from_to(int fd, void *buf, size_t len, int flags,
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| 111 | struct sockaddr *from, struct sockaddr *to,
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| 112 | socklen_t sa_size)
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| 113 | {
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| 114 | #ifndef IP_PKTINFO
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| 115 | (void)to; /* suppress "unused to" warning */
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| 116 | return recvfrom(fd, buf, len, flags, from, &sa_size);
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| 117 | #else
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| 118 | /* man recvmsg and man cmsg is needed to make sense of code below */
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| 119 | struct iovec iov[1];
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| 120 | union {
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| 121 | char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo))];
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| 122 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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| 123 | char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo))];
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| 124 | # endif
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| 125 | } u;
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| 126 | struct cmsghdr *cmsgptr;
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| 127 | struct msghdr msg;
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| 128 | ssize_t recv_length;
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| 129 |
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| 130 | iov[0].iov_base = buf;
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| 131 | iov[0].iov_len = len;
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| 132 |
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| 133 | memset(&msg, 0, sizeof(msg));
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| 134 | msg.msg_name = (struct sockaddr *)from;
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| 135 | msg.msg_namelen = sa_size;
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| 136 | msg.msg_iov = iov;
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| 137 | msg.msg_iovlen = 1;
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| 138 | msg.msg_control = &u;
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| 139 | msg.msg_controllen = sizeof(u);
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| 140 |
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| 141 | recv_length = recvmsg(fd, &msg, flags);
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| 142 | if (recv_length < 0)
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| 143 | return recv_length;
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| 144 |
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| 145 | # define to4 ((struct sockaddr_in*)to)
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| 146 | # define to6 ((struct sockaddr_in6*)to)
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| 147 | /* Here we try to retrieve destination IP and memorize it */
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| 148 | for (cmsgptr = CMSG_FIRSTHDR(&msg);
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| 149 | cmsgptr != NULL;
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| 150 | cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)
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| 151 | ) {
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| 152 | if (cmsgptr->cmsg_level == IPPROTO_IP
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| 153 | && cmsgptr->cmsg_type == IP_PKTINFO
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| 154 | ) {
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| 155 | const int IPI_ADDR_OFF = offsetof(struct in_pktinfo, ipi_addr);
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| 156 | to->sa_family = AF_INET;
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| 157 | /*# define pktinfo(cmsgptr) ( (struct in_pktinfo*)(CMSG_DATA(cmsgptr)) )*/
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| 158 | /*to4->sin_addr = pktinfo(cmsgptr)->ipi_addr; - may be unaligned */
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| 159 | memcpy(&to4->sin_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI_ADDR_OFF, sizeof(to4->sin_addr));
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| 160 | /*to4->sin_port = 123; - this data is not supplied by kernel */
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| 161 | break;
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| 162 | }
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| 163 | # if ENABLE_FEATURE_IPV6 && defined(IPV6_PKTINFO)
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| 164 | if (cmsgptr->cmsg_level == IPPROTO_IPV6
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| 165 | && cmsgptr->cmsg_type == IPV6_PKTINFO
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| 166 | ) {
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| 167 | const int IPI6_ADDR_OFF = offsetof(struct in6_pktinfo, ipi6_addr);
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| 168 | to->sa_family = AF_INET6;
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| 169 | /*# define pktinfo(cmsgptr) ( (struct in6_pktinfo*)(CMSG_DATA(cmsgptr)) )*/
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| 170 | /*to6->sin6_addr = pktinfo(cmsgptr)->ipi6_addr; - may be unaligned */
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| 171 | memcpy(&to6->sin6_addr, (char*)(CMSG_DATA(cmsgptr)) + IPI6_ADDR_OFF, sizeof(to6->sin6_addr));
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| 172 | /*to6->sin6_port = 123; */
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| 173 | break;
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| 174 | }
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| 175 | # endif
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| 176 | }
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| 177 | return recv_length;
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| 178 | #endif
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| 179 | }
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