It is totally wrong to use user specified IHL field for csum calculation which might lead to unexpectable cases.
So use new 'hdr->len' field which is calculated automatically after when header is built. Signed-off-by: Vadim Kochan <[email protected]> --- trafgen_l3.c | 4 +--- trafgen_proto.c | 4 +++- trafgen_proto.h | 1 + 3 files changed, 5 insertions(+), 4 deletions(-) diff --git a/trafgen_l3.c b/trafgen_l3.c index ae3f136..1c13cf5 100644 --- a/trafgen_l3.c +++ b/trafgen_l3.c @@ -53,10 +53,8 @@ static void ipv4_packet_finish(struct proto_hdr *hdr) if (!proto_field_is_set(hdr, IP4_CSUM)) { uint16_t csum; - uint8_t ihl; - ihl = proto_field_get_u8(hdr, IP4_IHL); - csum = htons(calc_csum(&pkt->payload[hdr->pkt_offset], ihl * 4)); + csum = htons(calc_csum(&pkt->payload[hdr->pkt_offset], hdr->len)); proto_field_set_u16(hdr, IP4_CSUM, bswap_16(csum)); } } diff --git a/trafgen_proto.c b/trafgen_proto.c index 1babba5..cb0c6ae 100644 --- a/trafgen_proto.c +++ b/trafgen_proto.c @@ -100,8 +100,10 @@ void proto_header_fields_add(struct proto_hdr *hdr, f->mask = fields[i].mask; f->pkt_offset = hdr->pkt_offset + fields[i].offset; - if (f->pkt_offset + f->len > pkt->len) + if (f->pkt_offset + f->len > pkt->len) { + hdr->len += f->len; set_fill(0, (f->pkt_offset + f->len) - pkt->len); + } } } diff --git a/trafgen_proto.h b/trafgen_proto.h index 822d841..72cd9f7 100644 --- a/trafgen_proto.h +++ b/trafgen_proto.h @@ -51,6 +51,7 @@ struct proto_hdr { uint16_t pkt_offset; struct proto_field *fields; size_t fields_count; + size_t len; void (*header_init)(struct proto_hdr *hdr); void (*header_finish)(struct proto_hdr *hdr); -- 2.6.3 -- You received this message because you are subscribed to the Google Groups "netsniff-ng" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
