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Diffstat (limited to 'networking/udhcp/clientpacket.c')
-rw-r--r--networking/udhcp/clientpacket.c25
1 files changed, 13 insertions, 12 deletions
diff --git a/networking/udhcp/clientpacket.c b/networking/udhcp/clientpacket.c
index 03473109f..b8190ba43 100644
--- a/networking/udhcp/clientpacket.c
+++ b/networking/udhcp/clientpacket.c
@@ -167,39 +167,40 @@ int send_release(uint32_t server, uint32_t ciaddr)
167} 167}
168 168
169 169
170/* return -1 on errors that are fatal for the socket, -2 for those that aren't */ 170/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
171int get_raw_packet(struct dhcpMessage *payload, int fd) 171int get_raw_packet(struct dhcpMessage *payload, int fd)
172{ 172{
173 int bytes; 173 int bytes;
174 struct udp_dhcp_packet packet; 174 struct udp_dhcp_packet packet;
175 uint16_t check; 175 uint16_t check;
176 176
177 memset(&packet, 0, sizeof(struct udp_dhcp_packet)); 177 memset(&packet, 0, sizeof(packet));
178 bytes = read(fd, &packet, sizeof(struct udp_dhcp_packet)); 178 bytes = safe_read(fd, &packet, sizeof(packet));
179 if (bytes < 0) { 179 if (bytes < 0) {
180 DEBUG("Cannot read on raw listening socket - ignoring"); 180 DEBUG("Cannot read on raw listening socket - ignoring");
181 sleep(1); /* possible down interface, looping condition */ 181 sleep(1); /* possible down interface, looping condition */
182 return -1; 182 return bytes; /* returns -1 */
183 } 183 }
184 184
185 if (bytes < (int) (sizeof(struct iphdr) + sizeof(struct udphdr))) { 185 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
186 DEBUG("Message too short, ignoring"); 186 DEBUG("Packet is too short, ignoring");
187 return -2; 187 return -2;
188 } 188 }
189 189
190 if (bytes < ntohs(packet.ip.tot_len)) { 190 if (bytes < ntohs(packet.ip.tot_len)) {
191 DEBUG("Truncated packet"); 191 /* packet is bigger than sizeof(packet), we did partial read */
192 DEBUG("Oversized packet, ignoring");
192 return -2; 193 return -2;
193 } 194 }
194 195
195 /* ignore any extra garbage bytes */ 196 /* ignore any extra garbage bytes */
196 bytes = ntohs(packet.ip.tot_len); 197 bytes = ntohs(packet.ip.tot_len);
197 198
198 /* Make sure its the right packet for us, and that it passes sanity checks */ 199 /* make sure its the right packet for us, and that it passes sanity checks */
199 if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION 200 if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
200 || packet.ip.ihl != (sizeof(packet.ip) >> 2) 201 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
201 || packet.udp.dest != htons(CLIENT_PORT) 202 || packet.udp.dest != htons(CLIENT_PORT)
202 || bytes > (int) sizeof(struct udp_dhcp_packet) 203 /* || bytes > (int) sizeof(packet) - can't happen */
203 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip)) 204 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
204 ) { 205 ) {
205 DEBUG("Unrelated/bogus packet"); 206 DEBUG("Unrelated/bogus packet");
@@ -211,12 +212,12 @@ int get_raw_packet(struct dhcpMessage *payload, int fd)
211 packet.ip.check = 0; 212 packet.ip.check = 0;
212 if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) { 213 if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
213 DEBUG("Bad IP header checksum, ignoring"); 214 DEBUG("Bad IP header checksum, ignoring");
214 return -1; 215 return -2;
215 } 216 }
216 217
217 /* verify UDP checksum. IP header has to be modified for this */ 218 /* verify UDP checksum. IP header has to be modified for this */
218 memset(&packet.ip, 0, offsetof(struct iphdr, protocol)); 219 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
219 /* fields which are not memset: protocol, check, saddr, daddr */ 220 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
220 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */ 221 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
221 check = packet.udp.check; 222 check = packet.udp.check;
222 packet.udp.check = 0; 223 packet.udp.check = 0;
@@ -228,7 +229,7 @@ int get_raw_packet(struct dhcpMessage *payload, int fd)
228 memcpy(payload, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp))); 229 memcpy(payload, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
229 230
230 if (payload->cookie != htonl(DHCP_MAGIC)) { 231 if (payload->cookie != htonl(DHCP_MAGIC)) {
231 bb_error_msg("received bogus message (bad magic) - ignoring"); 232 bb_error_msg("received bogus message (bad magic), ignoring");
232 return -2; 233 return -2;
233 } 234 }
234 DEBUG("Got valid DHCP packet"); 235 DEBUG("Got valid DHCP packet");