int FAST_FUNC udhcp_recv_kernel_packet(struct dhcp_packet *packet, int fd)
{
int bytes;
- unsigned char *vendor;
memset(packet, 0, sizeof(*packet));
bytes = safe_read(fd, packet, sizeof(*packet));
return bytes; /* returns -1 */
}
- if (packet->cookie != htonl(DHCP_MAGIC)) {
+ if (bytes < offsetof(struct dhcp_packet, options)
+ || packet->cookie != htonl(DHCP_MAGIC)
+ ) {
bb_info_msg("Packet with bad magic, ignoring");
return -2;
}
log1("Received a packet");
udhcp_dump_packet(packet);
- if (packet->op == BOOTREQUEST) {
- vendor = udhcp_get_option(packet, DHCP_VENDOR);
- if (vendor) {
-#if 0
- static const char broken_vendors[][8] = {
- "MSFT 98",
- ""
- };
- int i;
- for (i = 0; broken_vendors[i][0]; i++) {
- if (vendor[OPT_LEN - OPT_DATA] == (uint8_t)strlen(broken_vendors[i])
- && strncmp((char*)vendor, broken_vendors[i], vendor[OPT_LEN - OPT_DATA]) == 0
- ) {
- log1("Broken client (%s), forcing broadcast replies",
- broken_vendors[i]);
- packet->flags |= htons(BROADCAST_FLAG);
- }
- }
-#else
- if (vendor[OPT_LEN - OPT_DATA] == (uint8_t)(sizeof("MSFT 98")-1)
- && memcmp(vendor, "MSFT 98", sizeof("MSFT 98")-1) == 0
- ) {
- log1("Broken client (%s), forcing broadcast replies", "MSFT 98");
- packet->flags |= htons(BROADCAST_FLAG);
- }
-#endif
- }
- }
-
return bytes;
}
-uint16_t FAST_FUNC udhcp_checksum(void *addr, int count)
-{
- /* Compute Internet Checksum for "count" bytes
- * beginning at location "addr".
- */
- int32_t sum = 0;
- uint16_t *source = (uint16_t *) addr;
-
- while (count > 1) {
- /* This is the inner loop */
- sum += *source++;
- count -= 2;
- }
-
- /* Add left-over byte, if any */
- if (count > 0) {
- /* Make sure that the left-over byte is added correctly both
- * with little and big endian hosts */
- uint16_t tmp = 0;
- *(uint8_t*)&tmp = *(uint8_t*)source;
- sum += tmp;
- }
- /* Fold 32-bit sum to 16 bits */
- while (sum >> 16)
- sum = (sum & 0xffff) + (sum >> 16);
-
- return ~sum;
-}
-
/* Construct a ip/udp header for a packet, send packet */
int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
uint32_t source_nip, int source_port,
*
* In order to work with those buggy servers,
* we truncate packets after end option byte.
+ *
+ * However, RFC 1542 says "The IP Total Length and UDP Length
+ * must be large enough to contain the minimal BOOTP header of 300 octets".
+ * Thus, we retain enough padding to not go below 300 BOOTP bytes.
+ * Some devices have filters which drop DHCP packets shorter than that.
*/
padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(packet.data.options);
+ if (padding > DHCP_SIZE - 300)
+ padding = DHCP_SIZE - 300;
packet.ip.protocol = IPPROTO_UDP;
packet.ip.saddr = source_nip;
packet.udp.len = htons(UDP_DHCP_SIZE - padding);
/* for UDP checksumming, ip.len is set to UDP packet len */
packet.ip.tot_len = packet.udp.len;
- packet.udp.check = udhcp_checksum(&packet, IP_UDP_DHCP_SIZE - padding);
+ packet.udp.check = inet_cksum((uint16_t *)&packet,
+ IP_UDP_DHCP_SIZE - padding);
/* but for sending, it is set to IP packet len */
packet.ip.tot_len = htons(IP_UDP_DHCP_SIZE - padding);
packet.ip.ihl = sizeof(packet.ip) >> 2;
packet.ip.version = IPVERSION;
packet.ip.ttl = IPDEFTTL;
- packet.ip.check = udhcp_checksum(&packet.ip, sizeof(packet.ip));
+ packet.ip.check = inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip));
udhcp_dump_packet(dhcp_pkt);
result = sendto(fd, &packet, IP_UDP_DHCP_SIZE - padding, /*flags:*/ 0,
uint32_t source_nip, int source_port,
uint32_t dest_nip, int dest_port)
{
- struct sockaddr_in client;
+ struct sockaddr_in sa;
unsigned padding;
int fd;
int result = -1;
}
setsockopt_reuseaddr(fd);
- memset(&client, 0, sizeof(client));
- client.sin_family = AF_INET;
- client.sin_port = htons(source_port);
- client.sin_addr.s_addr = source_nip;
- if (bind(fd, (struct sockaddr *)&client, sizeof(client)) == -1) {
+ memset(&sa, 0, sizeof(sa));
+ sa.sin_family = AF_INET;
+ sa.sin_port = htons(source_port);
+ sa.sin_addr.s_addr = source_nip;
+ if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
msg = "bind(%s)";
goto ret_close;
}
- memset(&client, 0, sizeof(client));
- client.sin_family = AF_INET;
- client.sin_port = htons(dest_port);
- client.sin_addr.s_addr = dest_nip;
- if (connect(fd, (struct sockaddr *)&client, sizeof(client)) == -1) {
+ memset(&sa, 0, sizeof(sa));
+ sa.sin_family = AF_INET;
+ sa.sin_port = htons(dest_port);
+ sa.sin_addr.s_addr = dest_nip;
+ if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
msg = "connect";
goto ret_close;
}
udhcp_dump_packet(dhcp_pkt);
-
padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(dhcp_pkt->options);
+ if (padding > DHCP_SIZE - 300)
+ padding = DHCP_SIZE - 300;
result = safe_write(fd, dhcp_pkt, DHCP_SIZE - padding);
msg = "write";
ret_close:
projects / oweals / busybox.git / blobdiff