diff options
Diffstat (limited to 'src/openvpn/dhcp.c')
| -rw-r--r-- | src/openvpn/dhcp.c | 51 |
1 files changed, 4 insertions, 47 deletions
diff --git a/src/openvpn/dhcp.c b/src/openvpn/dhcp.c index fb28b27..c19370e 100644 --- a/src/openvpn/dhcp.c +++ b/src/openvpn/dhcp.c @@ -147,49 +147,6 @@ do_extract(struct dhcp *dhcp, int optlen) return ret; } -static uint16_t -udp_checksum(const uint8_t *buf, - const int len_udp, - const uint8_t *src_addr, - const uint8_t *dest_addr) -{ - uint16_t word16; - uint32_t sum = 0; - int i; - - /* make 16 bit words out of every two adjacent 8 bit words and */ - /* calculate the sum of all 16 bit words */ - for (i = 0; i < len_udp; i += 2) - { - word16 = ((buf[i] << 8) & 0xFF00) + ((i + 1 < len_udp) ? (buf[i+1] & 0xFF) : 0); - sum += word16; - } - - /* add the UDP pseudo header which contains the IP source and destination addresses */ - for (i = 0; i < 4; i += 2) - { - word16 = ((src_addr[i] << 8) & 0xFF00) + (src_addr[i+1] & 0xFF); - sum += word16; - } - for (i = 0; i < 4; i += 2) - { - word16 = ((dest_addr[i] << 8) & 0xFF00) + (dest_addr[i+1] & 0xFF); - sum += word16; - } - - /* the protocol number and the length of the UDP packet */ - sum += (uint16_t) OPENVPN_IPPROTO_UDP + (uint16_t) len_udp; - - /* keep only the last 16 bits of the 32 bit calculated sum and add the carries */ - while (sum >> 16) - { - sum = (sum & 0xFFFF) + (sum >> 16); - } - - /* Take the one's complement of sum */ - return ((uint16_t) ~sum); -} - in_addr_t dhcp_extract_router_msg(struct buffer *ipbuf) { @@ -210,10 +167,10 @@ dhcp_extract_router_msg(struct buffer *ipbuf) /* recompute the UDP checksum */ df->udp.check = 0; - df->udp.check = htons(udp_checksum((uint8_t *) &df->udp, - sizeof(struct openvpn_udphdr) + sizeof(struct dhcp) + optlen, - (uint8_t *)&df->ip.saddr, - (uint8_t *)&df->ip.daddr)); + df->udp.check = htons(ip_checksum(AF_INET, (uint8_t *)&df->udp, + sizeof(struct openvpn_udphdr) + sizeof(struct dhcp) + optlen, + (uint8_t *)&df->ip.saddr, (uint8_t *)&df->ip.daddr, + OPENVPN_IPPROTO_UDP)); /* only return the extracted Router address if DHCPACK */ if (message_type == DHCPACK) |