[3621] | 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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