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Diffstat (limited to 'src/openvpn/dhcp.c')
-rw-r--r--src/openvpn/dhcp.c51
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)