[PATCH libnetfilter_queue 0/1] src: Fix value returned by nfq_tcp_get_payload_len()

[PATCH libnetfilter_queue 0/1] src: Fix value returned by nfq_tcp_get_payload_len()

[Duncan Roe]

 This fix is similar to nfq_udp_get_payload_len fix b09038c
 
 Both nfq_tcp_get_payload_len & nfq_udp_get_payload_len are one-liners,
 unlike nfq_{tcp,udp}_get_payload which have checks for a malformed packet.
 
 It is not a given that programs will always call xx_get_payload before
 xx_get_payload_len so if you like I can make a v2 where
 nfq_{tcp,udp}_get_payload_len do have such checks.
 
 Cheers ... Duncan.

Duncan Roe (1):
  src: Fix value returned by nfq_tcp_get_payload_len()

 src/extra/tcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.14.5

[PATCH libnetfilter_queue 1/1] src: Fix value returned by nfq_tcp_get_payload_len()

[Duncan Roe]

Remember to subtract the TCP header length.

Signed-off-by: Duncan Roe <duncan_roe@optusnet.com.au>
---
 src/extra/tcp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/extra/tcp.c b/src/extra/tcp.c
index 0f83500..236663f 100644
--- a/src/extra/tcp.c
+++ b/src/extra/tcp.c
@@ -83,7 +83,7 @@ void *nfq_tcp_get_payload(struct tcphdr *tcph, struct pkt_buff *pktb)
 EXPORT_SYMBOL
 unsigned int nfq_tcp_get_payload_len(struct tcphdr *tcph, struct pkt_buff *pktb)
 {
-	return pktb->tail - pktb->transport_header;
+	return pktb->tail - pktb->transport_header -tcph->doff * 4;
 }
 
 /**
-- 
2.14.5

Re: [PATCH libnetfilter_queue 1/1] src: Fix value returned by nfq_tcp_get_payload_len()

[Pablo Neira Ayuso]

On Wed, Jan 08, 2020 at 08:42:24AM +1100, Duncan Roe wrote:
> Remember to subtract the TCP header length.

Applied, thanks.