Contents of /trunk/mkinitrd-magellan/busybox/networking/udhcp/clientpacket.c
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Sun May 30 11:32:42 2010 UTC (13 years, 11 months ago) by niro
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Sun May 30 11:32:42 2010 UTC (13 years, 11 months ago) by niro
File MIME type: text/plain
File size: 8008 byte(s)
-updated to busybox-1.16.1 and enabled blkid/uuid support in default config
1 | /* 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 | #include "common.h" |
11 | #include "dhcpd.h" |
12 | #include "dhcpc.h" |
13 | #include "options.h" |
14 | |
15 | //#include <features.h> |
16 | #if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined _NEWLIB_VERSION |
17 | #include <netpacket/packet.h> |
18 | #include <net/ethernet.h> |
19 | #else |
20 | #include <asm/types.h> |
21 | #include <linux/if_packet.h> |
22 | #include <linux/if_ether.h> |
23 | #endif |
24 | |
25 | |
26 | /* Create a random xid */ |
27 | uint32_t FAST_FUNC random_xid(void) |
28 | { |
29 | static smallint initialized; |
30 | |
31 | if (!initialized) { |
32 | srand(monotonic_us()); |
33 | initialized = 1; |
34 | } |
35 | return rand(); |
36 | } |
37 | |
38 | |
39 | /* Initialize the packet with the proper defaults */ |
40 | static void init_packet(struct dhcp_packet *packet, char type) |
41 | { |
42 | udhcp_init_header(packet, type); |
43 | memcpy(packet->chaddr, client_config.client_mac, 6); |
44 | if (client_config.clientid) |
45 | add_option_string(packet->options, client_config.clientid); |
46 | if (client_config.hostname) |
47 | add_option_string(packet->options, client_config.hostname); |
48 | if (client_config.fqdn) |
49 | add_option_string(packet->options, client_config.fqdn); |
50 | if ((type != DHCPDECLINE) && (type != DHCPRELEASE)) |
51 | add_option_string(packet->options, client_config.vendorclass); |
52 | } |
53 | |
54 | |
55 | /* Add a parameter request list for stubborn DHCP servers. Pull the data |
56 | * from the struct in options.c. Don't do bounds checking here because it |
57 | * goes towards the head of the packet. */ |
58 | static void add_param_req_option(struct dhcp_packet *packet) |
59 | { |
60 | uint8_t c; |
61 | int end = end_option(packet->options); |
62 | int i, len = 0; |
63 | |
64 | for (i = 0; (c = dhcp_options[i].code) != 0; i++) { |
65 | if (((dhcp_options[i].flags & OPTION_REQ) |
66 | && !client_config.no_default_options) |
67 | || (client_config.opt_mask[c >> 3] & (1 << (c & 7))) |
68 | ) { |
69 | packet->options[end + OPT_DATA + len] = c; |
70 | len++; |
71 | } |
72 | } |
73 | if (len) { |
74 | packet->options[end + OPT_CODE] = DHCP_PARAM_REQ; |
75 | packet->options[end + OPT_LEN] = len; |
76 | packet->options[end + OPT_DATA + len] = DHCP_END; |
77 | } |
78 | } |
79 | |
80 | /* RFC 2131 |
81 | * 4.4.4 Use of broadcast and unicast |
82 | * |
83 | * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM |
84 | * messages, unless the client knows the address of a DHCP server. |
85 | * The client unicasts DHCPRELEASE messages to the server. Because |
86 | * the client is declining the use of the IP address supplied by the server, |
87 | * the client broadcasts DHCPDECLINE messages. |
88 | * |
89 | * When the DHCP client knows the address of a DHCP server, in either |
90 | * INIT or REBOOTING state, the client may use that address |
91 | * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address. |
92 | * The client may also use unicast to send DHCPINFORM messages |
93 | * to a known DHCP server. If the client receives no response to DHCP |
94 | * messages sent to the IP address of a known DHCP server, the DHCP |
95 | * client reverts to using the IP broadcast address. |
96 | */ |
97 | |
98 | static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet) |
99 | { |
100 | return udhcp_send_raw_packet(packet, |
101 | /*src*/ INADDR_ANY, CLIENT_PORT, |
102 | /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR, |
103 | client_config.ifindex); |
104 | } |
105 | |
106 | |
107 | #if ENABLE_FEATURE_UDHCPC_ARPING |
108 | /* Broadcast a DHCP decline message */ |
109 | int FAST_FUNC send_decline(uint32_t xid, uint32_t server, uint32_t requested) |
110 | { |
111 | struct dhcp_packet packet; |
112 | |
113 | init_packet(&packet, DHCPDECLINE); |
114 | packet.xid = xid; |
115 | add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); |
116 | add_simple_option(packet.options, DHCP_SERVER_ID, server); |
117 | |
118 | bb_info_msg("Sending decline..."); |
119 | |
120 | return raw_bcast_from_client_config_ifindex(&packet); |
121 | } |
122 | #endif |
123 | |
124 | |
125 | /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */ |
126 | int FAST_FUNC send_discover(uint32_t xid, uint32_t requested) |
127 | { |
128 | struct dhcp_packet packet; |
129 | |
130 | init_packet(&packet, DHCPDISCOVER); |
131 | packet.xid = xid; |
132 | if (requested) |
133 | add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); |
134 | |
135 | /* Explicitly saying that we want RFC-compliant packets helps |
136 | * some buggy DHCP servers to NOT send bigger packets */ |
137 | add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576)); |
138 | |
139 | add_param_req_option(&packet); |
140 | |
141 | bb_info_msg("Sending discover..."); |
142 | return raw_bcast_from_client_config_ifindex(&packet); |
143 | } |
144 | |
145 | |
146 | /* Broadcast a DHCP request message */ |
147 | /* RFC 2131 3.1 paragraph 3: |
148 | * "The client _broadcasts_ a DHCPREQUEST message..." |
149 | */ |
150 | int FAST_FUNC send_select(uint32_t xid, uint32_t server, uint32_t requested) |
151 | { |
152 | struct dhcp_packet packet; |
153 | struct in_addr addr; |
154 | |
155 | init_packet(&packet, DHCPREQUEST); |
156 | packet.xid = xid; |
157 | |
158 | add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); |
159 | add_simple_option(packet.options, DHCP_SERVER_ID, server); |
160 | add_param_req_option(&packet); |
161 | |
162 | addr.s_addr = requested; |
163 | bb_info_msg("Sending select for %s...", inet_ntoa(addr)); |
164 | return raw_bcast_from_client_config_ifindex(&packet); |
165 | } |
166 | |
167 | |
168 | /* Unicast or broadcast a DHCP renew message */ |
169 | int FAST_FUNC send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr) |
170 | { |
171 | struct dhcp_packet packet; |
172 | |
173 | init_packet(&packet, DHCPREQUEST); |
174 | packet.xid = xid; |
175 | packet.ciaddr = ciaddr; |
176 | |
177 | add_param_req_option(&packet); |
178 | bb_info_msg("Sending renew..."); |
179 | if (server) |
180 | return udhcp_send_kernel_packet(&packet, |
181 | ciaddr, CLIENT_PORT, |
182 | server, SERVER_PORT); |
183 | |
184 | return raw_bcast_from_client_config_ifindex(&packet); |
185 | } |
186 | |
187 | |
188 | /* Unicast a DHCP release message */ |
189 | int FAST_FUNC send_release(uint32_t server, uint32_t ciaddr) |
190 | { |
191 | struct dhcp_packet packet; |
192 | |
193 | init_packet(&packet, DHCPRELEASE); |
194 | packet.xid = random_xid(); |
195 | packet.ciaddr = ciaddr; |
196 | |
197 | add_simple_option(packet.options, DHCP_SERVER_ID, server); |
198 | |
199 | bb_info_msg("Sending release..."); |
200 | return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT); |
201 | } |
202 | |
203 | |
204 | /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */ |
205 | int FAST_FUNC udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd) |
206 | { |
207 | int bytes; |
208 | struct ip_udp_dhcp_packet packet; |
209 | uint16_t check; |
210 | |
211 | memset(&packet, 0, sizeof(packet)); |
212 | bytes = safe_read(fd, &packet, sizeof(packet)); |
213 | if (bytes < 0) { |
214 | log1("Packet read error, ignoring"); |
215 | /* NB: possible down interface, etc. Caller should pause. */ |
216 | return bytes; /* returns -1 */ |
217 | } |
218 | |
219 | if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) { |
220 | log1("Packet is too short, ignoring"); |
221 | return -2; |
222 | } |
223 | |
224 | if (bytes < ntohs(packet.ip.tot_len)) { |
225 | /* packet is bigger than sizeof(packet), we did partial read */ |
226 | log1("Oversized packet, ignoring"); |
227 | return -2; |
228 | } |
229 | |
230 | /* ignore any extra garbage bytes */ |
231 | bytes = ntohs(packet.ip.tot_len); |
232 | |
233 | /* make sure its the right packet for us, and that it passes sanity checks */ |
234 | if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION |
235 | || packet.ip.ihl != (sizeof(packet.ip) >> 2) |
236 | || packet.udp.dest != htons(CLIENT_PORT) |
237 | /* || bytes > (int) sizeof(packet) - can't happen */ |
238 | || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip)) |
239 | ) { |
240 | log1("Unrelated/bogus packet, ignoring"); |
241 | return -2; |
242 | } |
243 | |
244 | /* verify IP checksum */ |
245 | check = packet.ip.check; |
246 | packet.ip.check = 0; |
247 | if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) { |
248 | log1("Bad IP header checksum, ignoring"); |
249 | return -2; |
250 | } |
251 | |
252 | /* verify UDP checksum. IP header has to be modified for this */ |
253 | memset(&packet.ip, 0, offsetof(struct iphdr, protocol)); |
254 | /* ip.xx fields which are not memset: protocol, check, saddr, daddr */ |
255 | packet.ip.tot_len = packet.udp.len; /* yes, this is needed */ |
256 | check = packet.udp.check; |
257 | packet.udp.check = 0; |
258 | if (check && check != udhcp_checksum(&packet, bytes)) { |
259 | log1("Packet with bad UDP checksum received, ignoring"); |
260 | return -2; |
261 | } |
262 | |
263 | memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp))); |
264 | |
265 | if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) { |
266 | bb_info_msg("Packet with bad magic, ignoring"); |
267 | return -2; |
268 | } |
269 | log1("Got valid DHCP packet"); |
270 | udhcp_dump_packet(dhcp_pkt); |
271 | return bytes - (sizeof(packet.ip) + sizeof(packet.udp)); |
272 | } |