diff options
| -rw-r--r-- | epan/dissectors/packet-ip.c | 56 |
1 files changed, 30 insertions, 26 deletions
diff --git a/epan/dissectors/packet-ip.c b/epan/dissectors/packet-ip.c index d1957d8a35..2bec7b5309 100644 --- a/epan/dissectors/packet-ip.c +++ b/epan/dissectors/packet-ip.c @@ -2039,42 +2039,46 @@ dissect_ip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree) doing its checksumming. */ iph->ip_len = tvb_get_ntohs(tvb, offset + 2); - /* Correct for zero-length TSO packets - * If ip_len is zero, assume TSO and use the reported length instead. Note - * that we need to use the frame/reported length instead of the - * actually-available length, just in case a snaplen was used on capture. */ - if (ip_tso_supported && !iph->ip_len) - iph->ip_len = tvb_reported_length(tvb); - if (iph->ip_len < hlen) { - col_add_fstr(pinfo->cinfo, COL_INFO, - "Bogus IP length (%u, less than header length %u)", - iph->ip_len, hlen); - if (tree) { - if (!iph->ip_len) { - tf = proto_tree_add_uint_format(ip_tree, hf_ip_len, tvb, offset + 2, 2, + if (ip_tso_supported && !iph->ip_len) { + /* TSO support enabled, and zero length. Assume the zero length is + * the result of TSO, and use the reported length instead. Note that + * we need to use the frame/reported length instead of the actually- + * available length, just in case a snaplen was used on capture. */ + iph->ip_len = tvb_reported_length(tvb); + if (tree) { + tf = proto_tree_add_uint_format_value(ip_tree, hf_ip_len, tvb, offset + 2, 2, iph->ip_len, - "Total length: 0 bytes (may be caused by \"TCP segmentation offload\" (TSO)?)"); - } else { + "%u bytes (reported as 0, presumed to be because of \"TCP segmentation offload\" (TSO))", + iph->ip_len); + PROTO_ITEM_SET_GENERATED(tf); + } + } else { + /* TSO support not enabled, or non-zero length, so treat it as an error. */ + col_add_fstr(pinfo->cinfo, COL_INFO, + "Bogus IP length (%u, less than header length %u)", + iph->ip_len, hlen); + if (tree) { tf = proto_tree_add_uint_format(ip_tree, hf_ip_len, tvb, offset + 2, 2, iph->ip_len, "Total length: %u bytes (bogus, less than header length %u)", iph->ip_len, hlen); } expert_add_info_format(pinfo, tf, PI_PROTOCOL, PI_ERROR, "Bogus IP length"); + /* Can't dissect any further */ + return; } - return; - } - - /* - * Now that we know that the total length of this IP datagram isn't - * obviously bogus, adjust the length of this tvbuff to include only - * the IP datagram. - */ - set_actual_length(tvb, iph->ip_len); + } else { + /* + * Now that we know that the total length of this IP datagram isn't + * obviously bogus, adjust the length of this tvbuff to include only + * the IP datagram. + */ + set_actual_length(tvb, iph->ip_len); - if (tree) - proto_tree_add_uint(ip_tree, hf_ip_len, tvb, offset + 2, 2, iph->ip_len); + if (tree) + proto_tree_add_uint(ip_tree, hf_ip_len, tvb, offset + 2, 2, iph->ip_len); + } iph->ip_id = tvb_get_ntohs(tvb, offset + 4); if (tree) |