diff options
Diffstat (limited to 'sbin/dhclient/packet.c')
| -rw-r--r-- | sbin/dhclient/packet.c | 53 |
1 files changed, 35 insertions, 18 deletions
diff --git a/sbin/dhclient/packet.c b/sbin/dhclient/packet.c index 3d7390c06ee0..fc0305a8cb0c 100644 --- a/sbin/dhclient/packet.c +++ b/sbin/dhclient/packet.c @@ -135,11 +135,14 @@ assemble_udp_ip_header(unsigned char *buf, int *bufix, u_int32_t from, udp.uh_ulen = htons(sizeof(udp) + len); memset(&udp.uh_sum, 0, sizeof(udp.uh_sum)); - udp.uh_sum = wrapsum(checksum((unsigned char *)&udp, sizeof(udp), - checksum(data, len, checksum((unsigned char *)&ip.ip_src, + udp.uh_sum = wrapsum(checksum(data, len, checksum((unsigned char *)&udp, + sizeof(udp), checksum((unsigned char *)&ip.ip_src, 2 * sizeof(ip.ip_src), IPPROTO_UDP + (u_int32_t)ntohs(udp.uh_ulen))))); + if (udp.uh_sum == htons(0)) + udp.uh_sum = htons(0xffff); + memcpy(&buf[*bufix], &udp, sizeof(udp)); *bufix += sizeof(udp); } @@ -166,7 +169,7 @@ decode_udp_ip_header(unsigned char *buf, int bufix, struct sockaddr_in *from, struct ip *ip; struct udphdr *udp; u_int32_t ip_len = (buf[bufix] & 0xf) << 2; - u_int32_t sum, usum; + u_int32_t sum, usum, pseudo_sum; static int ip_packets_seen; static int ip_packets_bad_checksum; static int udp_packets_seen; @@ -224,23 +227,37 @@ decode_udp_ip_header(unsigned char *buf, int bufix, struct sockaddr_in *from, } usum = udp->uh_sum; - udp->uh_sum = 0; - - sum = wrapsum(checksum((unsigned char *)udp, sizeof(*udp), - checksum(data, len, checksum((unsigned char *)&ip->ip_src, - 2 * sizeof(ip->ip_src), - IPPROTO_UDP + (u_int32_t)ntohs(udp->uh_ulen))))); - udp_packets_seen++; - if (usum && usum != sum) { - udp_packets_bad_checksum++; - if (udp_packets_seen > 4 && udp_packets_bad_checksum != 0 && - (udp_packets_seen / udp_packets_bad_checksum) < 2) { - note("%d bad udp checksums in %d packets", - udp_packets_bad_checksum, udp_packets_seen); - udp_packets_seen = udp_packets_bad_checksum = 0; + + if (usum != htons(0)) { + udp->uh_sum = 0; + + pseudo_sum = checksum((unsigned char *)&ip->ip_src, + 2 * sizeof(ip->ip_src), + IPPROTO_UDP + (u_int32_t)ntohs(udp->uh_ulen)); + sum = wrapsum(checksum(data, len, + checksum((unsigned char *)udp, sizeof(*udp), pseudo_sum))); + if (sum == htons(0)) + sum = htons(0xffff); + + /* + * In addition to accepting UDP packets with the correct + * checksum in the checksum field, accept also the ones which + * have the correct pseudo header checksum in the checksum + * field. This allows to process UDP packets, which have been + * marked for transmit checksum offloading by the sender side. + */ + if (usum != sum && usum != htons(pseudo_sum & 0x0000ffff)) { + udp_packets_bad_checksum++; + if (udp_packets_seen > 4 && + udp_packets_bad_checksum != 0 && + (udp_packets_seen / udp_packets_bad_checksum) < 2) { + note("%d bad udp checksums in %d packets", + udp_packets_bad_checksum, udp_packets_seen); + udp_packets_seen = udp_packets_bad_checksum = 0; + } + return (-1); } - return (-1); } memcpy(&from->sin_port, &udp->uh_sport, sizeof(udp->uh_sport)); |