| 1 | --- a/networking/udhcp/packet.c |
| 2 | +++ b/networking/udhcp/packet.c |
| 3 | @@ -165,6 +165,11 @@ uint16_t FAST_FUNC udhcp_checksum(void * |
| 4 | return ~sum; |
| 5 | } |
| 6 | |
| 7 | +int udhcp_get_payload_len(struct dhcp_packet *dhcp_pkt) |
| 8 | +{ |
| 9 | + return sizeof(struct dhcp_packet) - DHCP_OPTIONS_BUFSIZE + udhcp_end_option(dhcp_pkt->options) + sizeof(dhcp_pkt->options[0]); |
| 10 | +} |
| 11 | + |
| 12 | /* Construct a ip/udp header for a packet, send packet */ |
| 13 | int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt, |
| 14 | uint32_t source_nip, int source_port, |
| 15 | @@ -173,10 +178,10 @@ int FAST_FUNC udhcp_send_raw_packet(stru |
| 16 | { |
| 17 | struct sockaddr_ll dest_sll; |
| 18 | struct ip_udp_dhcp_packet packet; |
| 19 | - unsigned padding; |
| 20 | int fd; |
| 21 | int result = -1; |
| 22 | const char *msg; |
| 23 | + int p_len = udhcp_get_payload_len(dhcp_pkt); |
| 24 | |
| 25 | fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP)); |
| 26 | if (fd < 0) { |
| 27 | @@ -185,8 +190,8 @@ int FAST_FUNC udhcp_send_raw_packet(stru |
| 28 | } |
| 29 | |
| 30 | memset(&dest_sll, 0, sizeof(dest_sll)); |
| 31 | - memset(&packet, 0, offsetof(struct ip_udp_dhcp_packet, data)); |
| 32 | - packet.data = *dhcp_pkt; /* struct copy */ |
| 33 | + memset(&packet, 0, sizeof(packet)); |
| 34 | + memcpy(&(packet.data), dhcp_pkt, p_len); |
| 35 | |
| 36 | dest_sll.sll_family = AF_PACKET; |
| 37 | dest_sll.sll_protocol = htons(ETH_P_IP); |
| 38 | @@ -199,36 +204,24 @@ int FAST_FUNC udhcp_send_raw_packet(stru |
| 39 | goto ret_close; |
| 40 | } |
| 41 | |
| 42 | - /* We were sending full-sized DHCP packets (zero padded), |
| 43 | - * but some badly configured servers were seen dropping them. |
| 44 | - * Apparently they drop all DHCP packets >576 *ethernet* octets big, |
| 45 | - * whereas they may only drop packets >576 *IP* octets big |
| 46 | - * (which for typical Ethernet II means 590 octets: 6+6+2 + 576). |
| 47 | - * |
| 48 | - * In order to work with those buggy servers, |
| 49 | - * we truncate packets after end option byte. |
| 50 | - */ |
| 51 | - padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(packet.data.options); |
| 52 | - |
| 53 | packet.ip.protocol = IPPROTO_UDP; |
| 54 | packet.ip.saddr = source_nip; |
| 55 | packet.ip.daddr = dest_nip; |
| 56 | packet.udp.source = htons(source_port); |
| 57 | packet.udp.dest = htons(dest_port); |
| 58 | - /* size, excluding IP header: */ |
| 59 | - packet.udp.len = htons(UDP_DHCP_SIZE - padding); |
| 60 | - /* for UDP checksumming, ip.len is set to UDP packet len */ |
| 61 | + p_len += sizeof(packet.udp); |
| 62 | + packet.udp.len = htons(p_len); |
| 63 | packet.ip.tot_len = packet.udp.len; |
| 64 | - packet.udp.check = udhcp_checksum(&packet, IP_UDP_DHCP_SIZE - padding); |
| 65 | - /* but for sending, it is set to IP packet len */ |
| 66 | - packet.ip.tot_len = htons(IP_UDP_DHCP_SIZE - padding); |
| 67 | + p_len += sizeof(packet.ip); |
| 68 | + packet.udp.check = udhcp_checksum(&packet, p_len); |
| 69 | + packet.ip.tot_len = htons(p_len); |
| 70 | packet.ip.ihl = sizeof(packet.ip) >> 2; |
| 71 | packet.ip.version = IPVERSION; |
| 72 | packet.ip.ttl = IPDEFTTL; |
| 73 | packet.ip.check = udhcp_checksum(&packet.ip, sizeof(packet.ip)); |
| 74 | |
| 75 | udhcp_dump_packet(dhcp_pkt); |
| 76 | - result = sendto(fd, &packet, IP_UDP_DHCP_SIZE - padding, /*flags:*/ 0, |
| 77 | + result = sendto(fd, &packet, p_len, /*flags:*/ 0, |
| 78 | (struct sockaddr *) &dest_sll, sizeof(dest_sll)); |
| 79 | msg = "sendto"; |
| 80 | ret_close: |
| 81 | @@ -246,7 +239,6 @@ int FAST_FUNC udhcp_send_kernel_packet(s |
| 82 | uint32_t dest_nip, int dest_port) |
| 83 | { |
| 84 | struct sockaddr_in client; |
| 85 | - unsigned padding; |
| 86 | int fd; |
| 87 | int result = -1; |
| 88 | const char *msg; |
| 89 | @@ -277,9 +269,7 @@ int FAST_FUNC udhcp_send_kernel_packet(s |
| 90 | } |
| 91 | |
| 92 | udhcp_dump_packet(dhcp_pkt); |
| 93 | - |
| 94 | - padding = DHCP_OPTIONS_BUFSIZE - 1 - udhcp_end_option(dhcp_pkt->options); |
| 95 | - result = safe_write(fd, dhcp_pkt, DHCP_SIZE - padding); |
| 96 | + result = safe_write(fd, dhcp_pkt, udhcp_get_payload_len(dhcp_pkt)); |
| 97 | msg = "write"; |
| 98 | ret_close: |
| 99 | close(fd); |
| 100 | |
