Annotation of /trunk/mkinitrd-magellan/busybox/networking/udhcp/clientpacket.c
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Sat Sep 1 22:45:15 2007 UTC (16 years, 9 months ago) by niro
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Sat Sep 1 22:45:15 2007 UTC (16 years, 9 months ago) by niro
File MIME type: text/plain
File size: 6448 byte(s)
-import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
1 | niro | 532 | /* vi: set sw=4 ts=4: */ |
2 | /* clientpacket.c | ||
3 | * | ||
4 | * Packet generation and dispatching functions for the DHCP client. | ||
5 | * | ||
6 | * Russ Dill <Russ.Dill@asu.edu> July 2001 | ||
7 | * | ||
8 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. | ||
9 | */ | ||
10 | |||
11 | #include <features.h> | ||
12 | #if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined _NEWLIB_VERSION | ||
13 | #include <netpacket/packet.h> | ||
14 | #include <net/ethernet.h> | ||
15 | #else | ||
16 | #include <asm/types.h> | ||
17 | #include <linux/if_packet.h> | ||
18 | #include <linux/if_ether.h> | ||
19 | #endif | ||
20 | |||
21 | #include "common.h" | ||
22 | #include "dhcpd.h" | ||
23 | #include "dhcpc.h" | ||
24 | #include "options.h" | ||
25 | |||
26 | |||
27 | /* Create a random xid */ | ||
28 | unsigned long random_xid(void) | ||
29 | { | ||
30 | static int initialized; | ||
31 | if (!initialized) { | ||
32 | unsigned long seed; | ||
33 | |||
34 | if (open_read_close("/dev/urandom", &seed, sizeof(seed)) < 0) { | ||
35 | bb_info_msg("Cannot load seed " | ||
36 | "from /dev/urandom: %s", strerror(errno)); | ||
37 | seed = time(0); | ||
38 | } | ||
39 | srand(seed); | ||
40 | initialized++; | ||
41 | } | ||
42 | return rand(); | ||
43 | } | ||
44 | |||
45 | |||
46 | /* initialize a packet with the proper defaults */ | ||
47 | static void init_packet(struct dhcpMessage *packet, char type) | ||
48 | { | ||
49 | udhcp_init_header(packet, type); | ||
50 | memcpy(packet->chaddr, client_config.arp, 6); | ||
51 | if (client_config.clientid) | ||
52 | add_option_string(packet->options, client_config.clientid); | ||
53 | if (client_config.hostname) add_option_string(packet->options, client_config.hostname); | ||
54 | if (client_config.fqdn) add_option_string(packet->options, client_config.fqdn); | ||
55 | add_option_string(packet->options, client_config.vendorclass); | ||
56 | } | ||
57 | |||
58 | |||
59 | /* Add a parameter request list for stubborn DHCP servers. Pull the data | ||
60 | * from the struct in options.c. Don't do bounds checking here because it | ||
61 | * goes towards the head of the packet. */ | ||
62 | static void add_requests(struct dhcpMessage *packet) | ||
63 | { | ||
64 | int end = end_option(packet->options); | ||
65 | int i, len = 0; | ||
66 | |||
67 | packet->options[end + OPT_CODE] = DHCP_PARAM_REQ; | ||
68 | for (i = 0; dhcp_options[i].code; i++) | ||
69 | if (dhcp_options[i].flags & OPTION_REQ) | ||
70 | packet->options[end + OPT_DATA + len++] = dhcp_options[i].code; | ||
71 | packet->options[end + OPT_LEN] = len; | ||
72 | packet->options[end + OPT_DATA + len] = DHCP_END; | ||
73 | |||
74 | } | ||
75 | |||
76 | |||
77 | /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */ | ||
78 | int send_discover(unsigned long xid, unsigned long requested) | ||
79 | { | ||
80 | struct dhcpMessage packet; | ||
81 | |||
82 | init_packet(&packet, DHCPDISCOVER); | ||
83 | packet.xid = xid; | ||
84 | if (requested) | ||
85 | add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); | ||
86 | |||
87 | add_requests(&packet); | ||
88 | bb_info_msg("Sending discover..."); | ||
89 | return udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, | ||
90 | SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); | ||
91 | } | ||
92 | |||
93 | |||
94 | /* Broadcasts a DHCP request message */ | ||
95 | int send_selecting(unsigned long xid, unsigned long server, unsigned long requested) | ||
96 | { | ||
97 | struct dhcpMessage packet; | ||
98 | struct in_addr addr; | ||
99 | |||
100 | init_packet(&packet, DHCPREQUEST); | ||
101 | packet.xid = xid; | ||
102 | |||
103 | add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); | ||
104 | add_simple_option(packet.options, DHCP_SERVER_ID, server); | ||
105 | |||
106 | add_requests(&packet); | ||
107 | addr.s_addr = requested; | ||
108 | bb_info_msg("Sending select for %s...", inet_ntoa(addr)); | ||
109 | return udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, | ||
110 | SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); | ||
111 | } | ||
112 | |||
113 | |||
114 | /* Unicasts or broadcasts a DHCP renew message */ | ||
115 | int send_renew(unsigned long xid, unsigned long server, unsigned long ciaddr) | ||
116 | { | ||
117 | struct dhcpMessage packet; | ||
118 | int ret = 0; | ||
119 | |||
120 | init_packet(&packet, DHCPREQUEST); | ||
121 | packet.xid = xid; | ||
122 | packet.ciaddr = ciaddr; | ||
123 | |||
124 | add_requests(&packet); | ||
125 | bb_info_msg("Sending renew..."); | ||
126 | if (server) | ||
127 | ret = udhcp_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT); | ||
128 | else ret = udhcp_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, | ||
129 | SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); | ||
130 | return ret; | ||
131 | } | ||
132 | |||
133 | |||
134 | /* Unicasts a DHCP release message */ | ||
135 | int send_release(unsigned long server, unsigned long ciaddr) | ||
136 | { | ||
137 | struct dhcpMessage packet; | ||
138 | |||
139 | init_packet(&packet, DHCPRELEASE); | ||
140 | packet.xid = random_xid(); | ||
141 | packet.ciaddr = ciaddr; | ||
142 | |||
143 | add_simple_option(packet.options, DHCP_REQUESTED_IP, ciaddr); | ||
144 | add_simple_option(packet.options, DHCP_SERVER_ID, server); | ||
145 | |||
146 | bb_info_msg("Sending release..."); | ||
147 | return udhcp_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT); | ||
148 | } | ||
149 | |||
150 | |||
151 | /* return -1 on errors that are fatal for the socket, -2 for those that aren't */ | ||
152 | int get_raw_packet(struct dhcpMessage *payload, int fd) | ||
153 | { | ||
154 | int bytes; | ||
155 | struct udp_dhcp_packet packet; | ||
156 | uint32_t source, dest; | ||
157 | uint16_t check; | ||
158 | |||
159 | memset(&packet, 0, sizeof(struct udp_dhcp_packet)); | ||
160 | bytes = read(fd, &packet, sizeof(struct udp_dhcp_packet)); | ||
161 | if (bytes < 0) { | ||
162 | DEBUG("Cannot read on raw listening socket - ignoring"); | ||
163 | usleep(500000); /* possible down interface, looping condition */ | ||
164 | return -1; | ||
165 | } | ||
166 | |||
167 | if (bytes < (int) (sizeof(struct iphdr) + sizeof(struct udphdr))) { | ||
168 | DEBUG("Message too short, ignoring"); | ||
169 | return -2; | ||
170 | } | ||
171 | |||
172 | if (bytes < ntohs(packet.ip.tot_len)) { | ||
173 | DEBUG("Truncated packet"); | ||
174 | return -2; | ||
175 | } | ||
176 | |||
177 | /* ignore any extra garbage bytes */ | ||
178 | bytes = ntohs(packet.ip.tot_len); | ||
179 | |||
180 | /* Make sure its the right packet for us, and that it passes sanity checks */ | ||
181 | if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION | ||
182 | || packet.ip.ihl != sizeof(packet.ip) >> 2 | ||
183 | || packet.udp.dest != htons(CLIENT_PORT) | ||
184 | || bytes > (int) sizeof(struct udp_dhcp_packet) | ||
185 | || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip)) | ||
186 | ) { | ||
187 | DEBUG("Unrelated/bogus packet"); | ||
188 | return -2; | ||
189 | } | ||
190 | |||
191 | /* check IP checksum */ | ||
192 | check = packet.ip.check; | ||
193 | packet.ip.check = 0; | ||
194 | if (check != udhcp_checksum(&(packet.ip), sizeof(packet.ip))) { | ||
195 | DEBUG("bad IP header checksum, ignoring"); | ||
196 | return -1; | ||
197 | } | ||
198 | |||
199 | /* verify the UDP checksum by replacing the header with a psuedo header */ | ||
200 | source = packet.ip.saddr; | ||
201 | dest = packet.ip.daddr; | ||
202 | check = packet.udp.check; | ||
203 | packet.udp.check = 0; | ||
204 | memset(&packet.ip, 0, sizeof(packet.ip)); | ||
205 | |||
206 | packet.ip.protocol = IPPROTO_UDP; | ||
207 | packet.ip.saddr = source; | ||
208 | packet.ip.daddr = dest; | ||
209 | packet.ip.tot_len = packet.udp.len; /* cheat on the psuedo-header */ | ||
210 | if (check && check != udhcp_checksum(&packet, bytes)) { | ||
211 | bb_error_msg("packet with bad UDP checksum received, ignoring"); | ||
212 | return -2; | ||
213 | } | ||
214 | |||
215 | memcpy(payload, &(packet.data), bytes - (sizeof(packet.ip) + sizeof(packet.udp))); | ||
216 | |||
217 | if (ntohl(payload->cookie) != DHCP_MAGIC) { | ||
218 | bb_error_msg("received bogus message (bad magic) - ignoring"); | ||
219 | return -2; | ||
220 | } | ||
221 | DEBUG("oooooh!!! got some!"); | ||
222 | return bytes - (sizeof(packet.ip) + sizeof(packet.udp)); | ||
223 | |||
224 | } |