diff options
Diffstat (limited to 'networking/udhcp/clientpacket.c')
-rw-r--r-- | networking/udhcp/clientpacket.c | 239 |
1 files changed, 239 insertions, 0 deletions
diff --git a/networking/udhcp/clientpacket.c b/networking/udhcp/clientpacket.c new file mode 100644 index 000000000..ecbd7953f --- /dev/null +++ b/networking/udhcp/clientpacket.c | |||
@@ -0,0 +1,239 @@ | |||
1 | /* clientpacket.c | ||
2 | * | ||
3 | * Packet generation and dispatching functions for the DHCP client. | ||
4 | * | ||
5 | * Russ Dill <Russ.Dill@asu.edu> July 2001 | ||
6 | * | ||
7 | * This program is free software; you can redistribute it and/or modify | ||
8 | * it under the terms of the GNU General Public License as published by | ||
9 | * the Free Software Foundation; either version 2 of the License, or | ||
10 | * (at your option) any later version. | ||
11 | * | ||
12 | * This program is distributed in the hope that it will be useful, | ||
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
15 | * GNU General Public License for more details. | ||
16 | * | ||
17 | * You should have received a copy of the GNU General Public License | ||
18 | * along with this program; if not, write to the Free Software | ||
19 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | ||
20 | */ | ||
21 | |||
22 | #include <string.h> | ||
23 | #include <sys/socket.h> | ||
24 | #include <features.h> | ||
25 | #if __GLIBC__ >=2 && __GLIBC_MINOR >= 1 | ||
26 | #include <netpacket/packet.h> | ||
27 | #include <net/ethernet.h> | ||
28 | #else | ||
29 | #include <asm/types.h> | ||
30 | #include <linux/if_packet.h> | ||
31 | #include <linux/if_ether.h> | ||
32 | #endif | ||
33 | #include <stdlib.h> | ||
34 | #include <time.h> | ||
35 | #include <unistd.h> | ||
36 | #include <netinet/in.h> | ||
37 | #include <arpa/inet.h> | ||
38 | |||
39 | |||
40 | #include "dhcpd.h" | ||
41 | #include "packet.h" | ||
42 | #include "options.h" | ||
43 | #include "dhcpc.h" | ||
44 | #include "debug.h" | ||
45 | |||
46 | |||
47 | /* Create a random xid */ | ||
48 | unsigned long random_xid(void) | ||
49 | { | ||
50 | static int initialized; | ||
51 | if (!initialized) { | ||
52 | srand(time(0)); | ||
53 | initialized++; | ||
54 | } | ||
55 | return rand(); | ||
56 | } | ||
57 | |||
58 | |||
59 | /* initialize a packet with the proper defaults */ | ||
60 | static void init_packet(struct dhcpMessage *packet, char type) | ||
61 | { | ||
62 | struct vendor { | ||
63 | char vendor, length; | ||
64 | char str[sizeof("udhcp "VERSION)]; | ||
65 | } vendor_id = { DHCP_VENDOR, sizeof("udhcp "VERSION) - 1, "udhcp "VERSION}; | ||
66 | |||
67 | init_header(packet, type); | ||
68 | memcpy(packet->chaddr, client_config.arp, 6); | ||
69 | add_option_string(packet->options, client_config.clientid); | ||
70 | if (client_config.hostname) add_option_string(packet->options, client_config.hostname); | ||
71 | add_option_string(packet->options, (unsigned char *) &vendor_id); | ||
72 | } | ||
73 | |||
74 | |||
75 | /* Add a paramater request list for stubborn DHCP servers. Pull the data | ||
76 | * from the struct in options.c. Don't do bounds checking here because it | ||
77 | * goes towards the head of the packet. */ | ||
78 | static void add_requests(struct dhcpMessage *packet) | ||
79 | { | ||
80 | int end = end_option(packet->options); | ||
81 | int i, len = 0; | ||
82 | |||
83 | packet->options[end + OPT_CODE] = DHCP_PARAM_REQ; | ||
84 | for (i = 0; options[i].code; i++) | ||
85 | if (options[i].flags & OPTION_REQ) | ||
86 | packet->options[end + OPT_DATA + len++] = options[i].code; | ||
87 | packet->options[end + OPT_LEN] = len; | ||
88 | packet->options[end + OPT_DATA + len] = DHCP_END; | ||
89 | |||
90 | } | ||
91 | |||
92 | |||
93 | /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */ | ||
94 | int send_discover(unsigned long xid, unsigned long requested) | ||
95 | { | ||
96 | struct dhcpMessage packet; | ||
97 | |||
98 | init_packet(&packet, DHCPDISCOVER); | ||
99 | packet.xid = xid; | ||
100 | if (requested) | ||
101 | add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); | ||
102 | |||
103 | add_requests(&packet); | ||
104 | LOG(LOG_DEBUG, "Sending discover..."); | ||
105 | return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, | ||
106 | SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); | ||
107 | } | ||
108 | |||
109 | |||
110 | /* Broadcasts a DHCP request message */ | ||
111 | int send_selecting(unsigned long xid, unsigned long server, unsigned long requested) | ||
112 | { | ||
113 | struct dhcpMessage packet; | ||
114 | struct in_addr addr; | ||
115 | |||
116 | init_packet(&packet, DHCPREQUEST); | ||
117 | packet.xid = xid; | ||
118 | |||
119 | add_simple_option(packet.options, DHCP_REQUESTED_IP, requested); | ||
120 | add_simple_option(packet.options, DHCP_SERVER_ID, server); | ||
121 | |||
122 | add_requests(&packet); | ||
123 | addr.s_addr = requested; | ||
124 | LOG(LOG_DEBUG, "Sending select for %s...", inet_ntoa(addr)); | ||
125 | return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, | ||
126 | SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); | ||
127 | } | ||
128 | |||
129 | |||
130 | /* Unicasts or broadcasts a DHCP renew message */ | ||
131 | int send_renew(unsigned long xid, unsigned long server, unsigned long ciaddr) | ||
132 | { | ||
133 | struct dhcpMessage packet; | ||
134 | int ret = 0; | ||
135 | |||
136 | init_packet(&packet, DHCPREQUEST); | ||
137 | packet.xid = xid; | ||
138 | packet.ciaddr = ciaddr; | ||
139 | |||
140 | add_requests(&packet); | ||
141 | LOG(LOG_DEBUG, "Sending renew..."); | ||
142 | if (server) | ||
143 | ret = kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT); | ||
144 | else ret = raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, | ||
145 | SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex); | ||
146 | return ret; | ||
147 | } | ||
148 | |||
149 | |||
150 | /* Unicasts a DHCP release message */ | ||
151 | int send_release(unsigned long server, unsigned long ciaddr) | ||
152 | { | ||
153 | struct dhcpMessage packet; | ||
154 | |||
155 | init_packet(&packet, DHCPRELEASE); | ||
156 | packet.xid = random_xid(); | ||
157 | packet.ciaddr = ciaddr; | ||
158 | |||
159 | add_simple_option(packet.options, DHCP_REQUESTED_IP, ciaddr); | ||
160 | add_simple_option(packet.options, DHCP_SERVER_ID, server); | ||
161 | |||
162 | LOG(LOG_DEBUG, "Sending release..."); | ||
163 | return kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT); | ||
164 | } | ||
165 | |||
166 | |||
167 | /* return -1 on errors that are fatal for the socket, -2 for those that aren't */ | ||
168 | int get_raw_packet(struct dhcpMessage *payload, int fd) | ||
169 | { | ||
170 | int bytes; | ||
171 | struct udp_dhcp_packet packet; | ||
172 | u_int32_t source, dest; | ||
173 | u_int16_t check; | ||
174 | |||
175 | memset(&packet, 0, sizeof(struct udp_dhcp_packet)); | ||
176 | bytes = read(fd, &packet, sizeof(struct udp_dhcp_packet)); | ||
177 | if (bytes < 0) { | ||
178 | DEBUG(LOG_INFO, "couldn't read on raw listening socket -- ignoring"); | ||
179 | usleep(500000); /* possible down interface, looping condition */ | ||
180 | return -1; | ||
181 | } | ||
182 | |||
183 | if (bytes < (int) (sizeof(struct iphdr) + sizeof(struct udphdr))) { | ||
184 | DEBUG(LOG_INFO, "message too short, ignoring"); | ||
185 | return -2; | ||
186 | } | ||
187 | |||
188 | if (bytes < ntohs(packet.ip.tot_len)) { | ||
189 | DEBUG(LOG_INFO, "Truncated packet"); | ||
190 | return -2; | ||
191 | } | ||
192 | |||
193 | /* ignore any extra garbage bytes */ | ||
194 | bytes = ntohs(packet.ip.tot_len); | ||
195 | |||
196 | /* Make sure its the right packet for us, and that it passes sanity checks */ | ||
197 | if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION || | ||
198 | packet.ip.ihl != sizeof(packet.ip) >> 2 || packet.udp.dest != htons(CLIENT_PORT) || | ||
199 | bytes > (int) sizeof(struct udp_dhcp_packet) || | ||
200 | ntohs(packet.udp.len) != (short) (bytes - sizeof(packet.ip))) { | ||
201 | DEBUG(LOG_INFO, "unrelated/bogus packet"); | ||
202 | return -2; | ||
203 | } | ||
204 | |||
205 | /* check IP checksum */ | ||
206 | check = packet.ip.check; | ||
207 | packet.ip.check = 0; | ||
208 | if (check != checksum(&(packet.ip), sizeof(packet.ip))) { | ||
209 | DEBUG(LOG_INFO, "bad IP header checksum, ignoring"); | ||
210 | return -1; | ||
211 | } | ||
212 | |||
213 | /* verify the UDP checksum by replacing the header with a psuedo header */ | ||
214 | source = packet.ip.saddr; | ||
215 | dest = packet.ip.daddr; | ||
216 | check = packet.udp.check; | ||
217 | packet.udp.check = 0; | ||
218 | memset(&packet.ip, 0, sizeof(packet.ip)); | ||
219 | |||
220 | packet.ip.protocol = IPPROTO_UDP; | ||
221 | packet.ip.saddr = source; | ||
222 | packet.ip.daddr = dest; | ||
223 | packet.ip.tot_len = packet.udp.len; /* cheat on the psuedo-header */ | ||
224 | if (check && check != checksum(&packet, bytes)) { | ||
225 | DEBUG(LOG_ERR, "packet with bad UDP checksum received, ignoring"); | ||
226 | return -2; | ||
227 | } | ||
228 | |||
229 | memcpy(payload, &(packet.data), bytes - (sizeof(packet.ip) + sizeof(packet.udp))); | ||
230 | |||
231 | if (ntohl(payload->cookie) != DHCP_MAGIC) { | ||
232 | LOG(LOG_ERR, "received bogus message (bad magic) -- ignoring"); | ||
233 | return -2; | ||
234 | } | ||
235 | DEBUG(LOG_INFO, "oooooh!!! got some!"); | ||
236 | return bytes - (sizeof(packet.ip) + sizeof(packet.udp)); | ||
237 | |||
238 | } | ||
239 | |||