1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Copyright (C) 2011 Denys Vlasenko.
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4 | *
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5 | * Licensed under GPLv2, see file LICENSE in this source tree.
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6 | */
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7 | #include "common.h"
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8 | #include "d6_common.h"
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9 | #include "dhcpd.h"
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10 | #include <netinet/in.h>
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11 | #include <netinet/if_ether.h>
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12 | #include <netpacket/packet.h>
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13 |
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14 | #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2
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15 | void FAST_FUNC d6_dump_packet(struct d6_packet *packet)
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16 | {
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17 | if (dhcp_verbose < 2)
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18 | return;
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19 |
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20 | bb_error_msg(
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21 | "xid %x"
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22 | , packet->d6_xid32
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23 | );
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24 | //*bin2hex(buf, (void *) packet->chaddr, sizeof(packet->chaddr)) = '\0';
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25 | //bb_error_msg(" chaddr %s", buf);
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26 | }
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27 | #endif
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28 |
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29 | int FAST_FUNC d6_recv_kernel_packet(struct in6_addr *peer_ipv6
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30 | UNUSED_PARAM
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31 | , struct d6_packet *packet, int fd)
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32 | {
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33 | int bytes;
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34 |
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35 | memset(packet, 0, sizeof(*packet));
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36 | bytes = safe_read(fd, packet, sizeof(*packet));
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37 | if (bytes < 0) {
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38 | log1("packet read error, ignoring");
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39 | return bytes; /* returns -1 */
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40 | }
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41 |
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42 | if (bytes < offsetof(struct d6_packet, d6_options)) {
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43 | bb_error_msg("packet with bad magic, ignoring");
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44 | return -2;
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45 | }
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46 | log1("received %s", "a packet");
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47 | d6_dump_packet(packet);
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48 |
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49 | return bytes;
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50 | }
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51 |
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52 | /* Construct a ipv6+udp header for a packet, send packet */
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53 | int FAST_FUNC d6_send_raw_packet(
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54 | struct d6_packet *d6_pkt, unsigned d6_pkt_size,
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55 | struct in6_addr *src_ipv6, int source_port,
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56 | struct in6_addr *dst_ipv6, int dest_port, const uint8_t *dest_arp,
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57 | int ifindex)
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58 | {
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59 | struct sockaddr_ll dest_sll;
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60 | struct ip6_udp_d6_packet packet;
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61 | int fd;
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62 | int result = -1;
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63 | const char *msg;
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64 |
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65 | fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IPV6));
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66 | if (fd < 0) {
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67 | msg = "socket(%s)";
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68 | goto ret_msg;
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69 | }
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70 |
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71 | memset(&dest_sll, 0, sizeof(dest_sll));
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72 | memset(&packet, 0, offsetof(struct ip6_udp_d6_packet, data));
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73 | packet.data = *d6_pkt; /* struct copy */
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74 |
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75 | dest_sll.sll_family = AF_PACKET;
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76 | dest_sll.sll_protocol = htons(ETH_P_IPV6);
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77 | dest_sll.sll_ifindex = ifindex;
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78 | dest_sll.sll_halen = 6;
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79 | memcpy(dest_sll.sll_addr, dest_arp, 6);
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80 |
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81 | if (bind(fd, (struct sockaddr *)&dest_sll, sizeof(dest_sll)) < 0) {
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82 | msg = "bind(%s)";
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83 | goto ret_close;
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84 | }
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85 |
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86 | packet.ip6.ip6_vfc = (6 << 4); /* 4 bits version, top 4 bits of tclass */
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87 | if (src_ipv6)
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88 | packet.ip6.ip6_src = *src_ipv6; /* struct copy */
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89 | packet.ip6.ip6_dst = *dst_ipv6; /* struct copy */
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90 | packet.udp.source = htons(source_port);
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91 | packet.udp.dest = htons(dest_port);
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92 | /* size, excluding IP header: */
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93 | packet.udp.len = htons(sizeof(struct udphdr) + d6_pkt_size);
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94 | packet.ip6.ip6_plen = packet.udp.len;
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95 | /*
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96 | * Someone was smoking weed (at least) while inventing UDP checksumming:
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97 | * UDP checksum skips first four bytes of IPv6 header.
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98 | * 'next header' field should be summed as if it is one more byte
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99 | * to the right, therefore we write its value (IPPROTO_UDP)
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100 | * into ip6_hlim, and its 'real' location remains zero-filled for now.
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101 | */
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102 | packet.ip6.ip6_hlim = IPPROTO_UDP;
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103 | packet.udp.check = inet_cksum(
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104 | (uint16_t *)&packet + 2,
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105 | offsetof(struct ip6_udp_d6_packet, data) - 4 + d6_pkt_size
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106 | );
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107 | /* fix 'hop limit' and 'next header' after UDP checksumming */
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108 | packet.ip6.ip6_hlim = 1; /* observed Windows machines to use hlim=1 */
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109 | packet.ip6.ip6_nxt = IPPROTO_UDP;
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110 |
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111 | d6_dump_packet(d6_pkt);
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112 | result = sendto(fd, &packet, offsetof(struct ip6_udp_d6_packet, data) + d6_pkt_size,
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113 | /*flags:*/ 0,
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114 | (struct sockaddr *) &dest_sll, sizeof(dest_sll)
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115 | );
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116 | msg = "sendto";
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117 | ret_close:
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118 | close(fd);
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119 | if (result < 0) {
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120 | ret_msg:
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121 | bb_perror_msg(msg, "PACKET");
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122 | }
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123 | return result;
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124 | }
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125 |
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126 | /* Let the kernel do all the work for packet generation */
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127 | int FAST_FUNC d6_send_kernel_packet(
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128 | struct d6_packet *d6_pkt, unsigned d6_pkt_size,
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129 | struct in6_addr *src_ipv6, int source_port,
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130 | struct in6_addr *dst_ipv6, int dest_port)
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131 | {
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132 | struct sockaddr_in6 sa;
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133 | int fd;
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134 | int result = -1;
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135 | const char *msg;
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136 |
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137 | fd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
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138 | if (fd < 0) {
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139 | msg = "socket(%s)";
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140 | goto ret_msg;
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141 | }
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142 | setsockopt_reuseaddr(fd);
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143 |
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144 | memset(&sa, 0, sizeof(sa));
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145 | sa.sin6_family = AF_INET6;
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146 | sa.sin6_port = htons(source_port);
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147 | sa.sin6_addr = *src_ipv6; /* struct copy */
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148 | if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
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149 | msg = "bind(%s)";
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150 | goto ret_close;
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151 | }
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152 |
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153 | memset(&sa, 0, sizeof(sa));
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154 | sa.sin6_family = AF_INET6;
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155 | sa.sin6_port = htons(dest_port);
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156 | sa.sin6_addr = *dst_ipv6; /* struct copy */
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157 | if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
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158 | msg = "connect";
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159 | goto ret_close;
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160 | }
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161 |
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162 | d6_dump_packet(d6_pkt);
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163 | result = safe_write(fd, d6_pkt, d6_pkt_size);
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164 | msg = "write";
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165 | ret_close:
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166 | close(fd);
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167 | if (result < 0) {
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168 | ret_msg:
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169 | bb_perror_msg(msg, "UDP");
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170 | }
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171 | return result;
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172 | }
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