All in_cksum() does is IPv4 header checksum verification, so name it accordingly and in process simplify it a bit.
Signed-off-by: Vitezslav Samel vitezslav@samel.cz --- src/packet.c | 22 ++++++++-------------- 1 files changed, 8 insertions(+), 14 deletions(-)
diff --git a/src/packet.c b/src/packet.c index bc8ed21..8de68e4 100644 --- a/src/packet.c +++ b/src/packet.c @@ -38,12 +38,14 @@ packet.c - routines to open the raw socket, read socket data and pkt_cast_hdrp_l3off_t(hdr, pkt, 0)
/* code taken from http://www.faqs.org/rfcs/rfc1071.html. See section 4.1 "C" */ -static int in_cksum(u_short * addr, int len) +static int verify_ipv4_hdr_chksum(struct iphdr *ip) { register int sum = 0; + u_short *addr = (u_short *)ip; + int len = ip->ihl * 4;
while (len > 1) { - sum += *(u_short *) addr++; + sum += *addr++; len -= 2; }
@@ -53,7 +55,9 @@ static int in_cksum(u_short * addr, int len) while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16);
- return (u_short) (~sum); + sum = (u_short) (~sum); + + return sum == 0; }
static int packet_adjust(struct pkt_hdr *pkt) @@ -198,19 +202,9 @@ again: switch (pkt->pkt_protocol) { case ETH_P_IP: { struct iphdr *ip = pkt->iphdr; - int hdr_check; - register int ip_checksum; in_port_t f_sport = 0, f_dport = 0;
- /* - * Compute and verify IP header checksum. - */ - - ip_checksum = ip->check; - ip->check = 0; - hdr_check = in_cksum((u_short *) pkt->iphdr, pkt_iph_len(pkt)); - - if ((hdr_check != ip_checksum)) + if (!verify_ipv4_hdr_chksum(ip)) return CHECKSUM_ERROR;
if ((ip->protocol == IPPROTO_TCP || ip->protocol == IPPROTO_UDP)