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
d6_dump_packet(struct d6_packet * packet)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
d6_recv_kernel_packet(struct in6_addr * peer_ipv6 UNUSED_PARAM,struct d6_packet * packet,int fd)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 */
d6_send_raw_packet(struct d6_packet * d6_pkt,unsigned d6_pkt_size,struct in6_addr * src_ipv6,int source_port,struct in6_addr * dst_ipv6,int dest_port,const uint8_t * dest_arp,int ifindex)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 */
d6_send_kernel_packet(struct d6_packet * d6_pkt,unsigned d6_pkt_size,struct in6_addr * src_ipv6,int source_port,struct in6_addr * dst_ipv6,int dest_port)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