blob: e166f520de994b50c2c9f77094297ee4dc4e103e
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Copyright (C) 2011 Denys Vlasenko. |
4 | * |
5 | * Licensed under GPLv2, see file LICENSE in this source tree. |
6 | */ |
7 | #include "common.h" |
8 | #include "d6_common.h" |
9 | #include "dhcpd.h" |
10 | #include <netinet/in.h> |
11 | #include <netinet/if_ether.h> |
12 | #include <netpacket/packet.h> |
13 | |
14 | #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2 |
15 | void FAST_FUNC d6_dump_packet(struct d6_packet *packet) |
16 | { |
17 | if (dhcp_verbose < 2) |
18 | return; |
19 | |
20 | bb_error_msg( |
21 | "xid %x" |
22 | , packet->d6_xid32 |
23 | ); |
24 | //*bin2hex(buf, (void *) packet->chaddr, sizeof(packet->chaddr)) = '\0'; |
25 | //bb_error_msg(" chaddr %s", buf); |
26 | } |
27 | #endif |
28 | |
29 | int FAST_FUNC d6_recv_kernel_packet(struct in6_addr *peer_ipv6 |
30 | UNUSED_PARAM |
31 | , struct d6_packet *packet, int fd) |
32 | { |
33 | int bytes; |
34 | |
35 | memset(packet, 0, sizeof(*packet)); |
36 | bytes = safe_read(fd, packet, sizeof(*packet)); |
37 | if (bytes < 0) { |
38 | log1("packet read error, ignoring"); |
39 | return bytes; /* returns -1 */ |
40 | } |
41 | |
42 | if (bytes < offsetof(struct d6_packet, d6_options)) { |
43 | bb_error_msg("packet with bad magic, ignoring"); |
44 | return -2; |
45 | } |
46 | log1("received %s", "a packet"); |
47 | d6_dump_packet(packet); |
48 | |
49 | return bytes; |
50 | } |
51 | |
52 | /* Construct a ipv6+udp header for a packet, send packet */ |
53 | int FAST_FUNC d6_send_raw_packet( |
54 | struct d6_packet *d6_pkt, unsigned d6_pkt_size, |
55 | struct in6_addr *src_ipv6, int source_port, |
56 | struct in6_addr *dst_ipv6, int dest_port, const uint8_t *dest_arp, |
57 | int ifindex) |
58 | { |
59 | struct sockaddr_ll dest_sll; |
60 | struct ip6_udp_d6_packet packet; |
61 | int fd; |
62 | int result = -1; |
63 | const char *msg; |
64 | |
65 | fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IPV6)); |
66 | if (fd < 0) { |
67 | msg = "socket(%s)"; |
68 | goto ret_msg; |
69 | } |
70 | |
71 | memset(&dest_sll, 0, sizeof(dest_sll)); |
72 | memset(&packet, 0, offsetof(struct ip6_udp_d6_packet, data)); |
73 | packet.data = *d6_pkt; /* struct copy */ |
74 | |
75 | dest_sll.sll_family = AF_PACKET; |
76 | dest_sll.sll_protocol = htons(ETH_P_IPV6); |
77 | dest_sll.sll_ifindex = ifindex; |
78 | dest_sll.sll_halen = 6; |
79 | memcpy(dest_sll.sll_addr, dest_arp, 6); |
80 | |
81 | if (bind(fd, (struct sockaddr *)&dest_sll, sizeof(dest_sll)) < 0) { |
82 | msg = "bind(%s)"; |
83 | goto ret_close; |
84 | } |
85 | |
86 | packet.ip6.ip6_vfc = (6 << 4); /* 4 bits version, top 4 bits of tclass */ |
87 | if (src_ipv6) |
88 | packet.ip6.ip6_src = *src_ipv6; /* struct copy */ |
89 | packet.ip6.ip6_dst = *dst_ipv6; /* struct copy */ |
90 | packet.udp.source = htons(source_port); |
91 | packet.udp.dest = htons(dest_port); |
92 | /* size, excluding IP header: */ |
93 | packet.udp.len = htons(sizeof(struct udphdr) + d6_pkt_size); |
94 | packet.ip6.ip6_plen = packet.udp.len; |
95 | /* |
96 | * Someone was smoking weed (at least) while inventing UDP checksumming: |
97 | * UDP checksum skips first four bytes of IPv6 header. |
98 | * 'next header' field should be summed as if it is one more byte |
99 | * to the right, therefore we write its value (IPPROTO_UDP) |
100 | * into ip6_hlim, and its 'real' location remains zero-filled for now. |
101 | */ |
102 | packet.ip6.ip6_hlim = IPPROTO_UDP; |
103 | packet.udp.check = inet_cksum( |
104 | (uint16_t *)&packet + 2, |
105 | offsetof(struct ip6_udp_d6_packet, data) - 4 + d6_pkt_size |
106 | ); |
107 | /* fix 'hop limit' and 'next header' after UDP checksumming */ |
108 | packet.ip6.ip6_hlim = 1; /* observed Windows machines to use hlim=1 */ |
109 | packet.ip6.ip6_nxt = IPPROTO_UDP; |
110 | |
111 | d6_dump_packet(d6_pkt); |
112 | result = sendto(fd, &packet, offsetof(struct ip6_udp_d6_packet, data) + d6_pkt_size, |
113 | /*flags:*/ 0, |
114 | (struct sockaddr *) &dest_sll, sizeof(dest_sll) |
115 | ); |
116 | msg = "sendto"; |
117 | ret_close: |
118 | close(fd); |
119 | if (result < 0) { |
120 | ret_msg: |
121 | bb_perror_msg(msg, "PACKET"); |
122 | } |
123 | return result; |
124 | } |
125 | |
126 | /* Let the kernel do all the work for packet generation */ |
127 | int FAST_FUNC d6_send_kernel_packet( |
128 | struct d6_packet *d6_pkt, unsigned d6_pkt_size, |
129 | struct in6_addr *src_ipv6, int source_port, |
130 | struct in6_addr *dst_ipv6, int dest_port) |
131 | { |
132 | struct sockaddr_in6 sa; |
133 | int fd; |
134 | int result = -1; |
135 | const char *msg; |
136 | |
137 | fd = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP); |
138 | if (fd < 0) { |
139 | msg = "socket(%s)"; |
140 | goto ret_msg; |
141 | } |
142 | setsockopt_reuseaddr(fd); |
143 | |
144 | memset(&sa, 0, sizeof(sa)); |
145 | sa.sin6_family = AF_INET6; |
146 | sa.sin6_port = htons(source_port); |
147 | sa.sin6_addr = *src_ipv6; /* struct copy */ |
148 | if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) { |
149 | msg = "bind(%s)"; |
150 | goto ret_close; |
151 | } |
152 | |
153 | memset(&sa, 0, sizeof(sa)); |
154 | sa.sin6_family = AF_INET6; |
155 | sa.sin6_port = htons(dest_port); |
156 | sa.sin6_addr = *dst_ipv6; /* struct copy */ |
157 | if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) { |
158 | msg = "connect"; |
159 | goto ret_close; |
160 | } |
161 | |
162 | d6_dump_packet(d6_pkt); |
163 | result = safe_write(fd, d6_pkt, d6_pkt_size); |
164 | msg = "write"; |
165 | ret_close: |
166 | close(fd); |
167 | if (result < 0) { |
168 | ret_msg: |
169 | bb_perror_msg(msg, "UDP"); |
170 | } |
171 | return result; |
172 | } |
173 |