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