X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Flibsystemd-network%2Fdhcp-packet.c;h=3e2fb96c27f3054633dc7430381a40f3deb22303;hb=ecde7065f7b11a7a226d2f7b0e90e998a6347a59;hp=3b62c2572f52608f7990b64bb20355319ca6a21a;hpb=6e34949d7207f9dff4e2b01a3037a0af88e1c25c;p=elogind.git diff --git a/src/libsystemd-network/dhcp-packet.c b/src/libsystemd-network/dhcp-packet.c index 3b62c2572..3e2fb96c2 100644 --- a/src/libsystemd-network/dhcp-packet.c +++ b/src/libsystemd-network/dhcp-packet.c @@ -38,52 +38,70 @@ #define DHCP_CLIENT_MIN_OPTIONS_SIZE 312 int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid, - uint8_t type, uint8_t **opt, size_t *optlen) { - int err; + uint8_t type, size_t optlen, size_t *optoffset) { + size_t offset = 0; + int r; assert(op == BOOTREQUEST || op == BOOTREPLY); - *opt = (uint8_t *)(message + 1); - - if (*optlen < 4) - return -ENOBUFS; - *optlen -= 4; - message->op = op; message->htype = ARPHRD_ETHER; message->hlen = ETHER_ADDR_LEN; message->xid = htobe32(xid); + message->magic = htobe32(DHCP_MAGIC_COOKIE); - (*opt)[0] = 0x63; - (*opt)[1] = 0x82; - (*opt)[2] = 0x53; - (*opt)[3] = 0x63; - - *opt += 4; + r = dhcp_option_append(message, optlen, &offset, 0, + DHCP_OPTION_MESSAGE_TYPE, 1, &type); + if (r < 0) + return r; - err = dhcp_option_append(opt, optlen, DHCP_OPTION_MESSAGE_TYPE, 1, - &type); - if (err < 0) - return err; + *optoffset = offset; return 0; } -uint16_t dhcp_packet_checksum(void *buf, int len) { - uint32_t sum; - uint16_t *check; - int i; - uint8_t *odd; +uint16_t dhcp_packet_checksum(void *buf, size_t len) { + uint64_t *buf_64 = buf; + uint64_t *end_64 = (uint64_t*)buf + (len / sizeof(uint64_t)); + uint32_t *buf_32; + uint16_t *buf_16; + uint8_t *buf_8; + uint64_t sum = 0; - sum = 0; - check = buf; + while (buf_64 < end_64) { + sum += *buf_64; + if (sum < *buf_64) + sum++; + + buf_64 ++; + } - for (i = 0; i < len / 2 ; i++) - sum += check[i]; + buf_32 = (uint32_t*)buf_64; - if (len & 0x01) { - odd = buf; - sum += odd[len - 1]; + if (len & sizeof(uint32_t)) { + sum += *buf_32; + if (sum < *buf_32) + sum++; + + buf_32 ++; + } + + buf_16 = (uint16_t*)buf_32; + + if (len & sizeof(uint16_t)) { + sum += *buf_16; + if (sum < *buf_16) + sum ++; + + buf_16 ++; + } + + buf_8 = (uint8_t*)buf_16; + + if (len & sizeof(uint8_t)) { + sum += *buf_8; + if (sum < *buf_8) + sum++; } while (sum >> 16) @@ -99,6 +117,8 @@ void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr, packet->ip.ihl = DHCP_IP_SIZE / 4; packet->ip.tot_len = htobe16(len); + packet->ip.tos = IPTOS_CLASS_CS6; + packet->ip.protocol = IPPROTO_UDP; packet->ip.saddr = source_addr; packet->ip.daddr = destination_addr; @@ -123,61 +143,58 @@ int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum) { /* IP */ - if (len < DHCP_IP_SIZE) { - log_dhcp_client(client, "ignoring packet: packet (%zu bytes) " - " smaller than IP header (%u bytes)", len, - DHCP_IP_SIZE); - return -EINVAL; - } - if (packet->ip.version != IPVERSION) { - log_dhcp_client(client, "ignoring packet: not IPv4"); + log_debug("ignoring packet: not IPv4"); return -EINVAL; } if (packet->ip.ihl < 5) { - log_dhcp_client(client, "ignoring packet: IPv4 IHL (%u words) invalid", - packet->ip.ihl); + log_debug("ignoring packet: IPv4 IHL (%u words) invalid", + packet->ip.ihl); return -EINVAL; } hdrlen = packet->ip.ihl * 4; if (hdrlen < 20) { - log_dhcp_client(client, "ignoring packet: IPv4 IHL (%zu bytes) " - "smaller than minimum (20 bytes)", hdrlen); + log_debug("ignoring packet: IPv4 IHL (%zu bytes) " + "smaller than minimum (20 bytes)", hdrlen); return -EINVAL; } if (len < hdrlen) { - log_dhcp_client(client, "ignoring packet: packet (%zu bytes) " - "smaller than expected (%zu) by IP header", len, - hdrlen); - return -EINVAL; - } - - if (dhcp_packet_checksum(&packet->ip, hdrlen)) { - log_dhcp_client(client, "ignoring packet: invalid IP checksum"); + log_debug("ignoring packet: packet (%zu bytes) " + "smaller than expected (%zu) by IP header", len, + hdrlen); return -EINVAL; } /* UDP */ if (packet->ip.protocol != IPPROTO_UDP) { - log_dhcp_client(client, "ignoring packet: not UDP"); + log_debug("ignoring packet: not UDP"); return -EINVAL; } - if (len < DHCP_IP_UDP_SIZE) { - log_dhcp_client(client, "ignoring packet: packet (%zu bytes) " - " smaller than IP+UDP header (%u bytes)", len, - DHCP_IP_UDP_SIZE); + if (len < hdrlen + be16toh(packet->udp.len)) { + log_debug("ignoring packet: packet (%zu bytes) " + "smaller than expected (%zu) by UDP header", len, + hdrlen + be16toh(packet->udp.len)); return -EINVAL; } - if (len < hdrlen + be16toh(packet->udp.len)) { - log_dhcp_client(client, "ignoring packet: packet (%zu bytes) " - "smaller than expected (%zu) by UDP header", len, - hdrlen + be16toh(packet->udp.len)); + if (be16toh(packet->udp.dest) != DHCP_PORT_CLIENT) { + log_debug("ignoring packet: to port %u, which " + "is not the DHCP client port (%u)", + be16toh(packet->udp.dest), DHCP_PORT_CLIENT); + return -EINVAL; + } + + /* checksums - computing these is relatively expensive, so only do it + if all the other checks have passed + */ + + if (dhcp_packet_checksum(&packet->ip, hdrlen)) { + log_debug("ignoring packet: invalid IP checksum"); return -EINVAL; } @@ -187,17 +204,10 @@ int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum) { if (dhcp_packet_checksum(&packet->ip.ttl, be16toh(packet->udp.len) + 12)) { - log_dhcp_client(client, "ignoring packet: invalid UDP checksum"); + log_debug("ignoring packet: invalid UDP checksum"); return -EINVAL; } } - if (be16toh(packet->udp.dest) != DHCP_PORT_CLIENT) { - log_dhcp_client(client, "ignoring packet: to port %u, which " - "is not the DHCP client port (%u)", - be16toh(packet->udp.dest), DHCP_PORT_CLIENT); - return -EINVAL; - } - return 0; }