[Winpcap-users] pcap_sendpacket sends only 4 bytes...!

[Valpondi Hereza, Fabio]

Hi Boaz,

you are right!!! What an childish mistake...!!

I used "sizeof(header->length)" instead of "header->length". I tried it, and it works perfectly!

Thanks again!



________________________________
Von: winpcap-users-bounces at winpcap.org [mailto:winpcap-users-bounces at winpcap.org] Im Auftrag von Boaz Brickner
Gesendet: Donnerstag, 25. Februar 2010 12:47
An: winpcap-users at winpcap.org
Betreff: Re: [Winpcap-users] pcap_sendpacket sends only 4 bytes...!

Hi,

It seems that your bug is "sizeof(pkt_data_iface1_2) is the buffer size."
sizeof is an operator that returns the size of the type and not the length of the buffer.
http://msdn.microsoft.com/en-us/library/4s7x1k91%28VS.71%29.aspx

You should use the length of the buffer you want to send.

When you receive a packet, you also receive a packet header (pcap_pkthdr), which contains the length of the packet buffer (caplen).
You should use this length and you should not use the sizeof operator.

By the way, the sizeof operator returns 4 when you use it on an int type or a pointer type, so this is why you got only 4 bytes.

I hope this helps,

Boaz.


Try Pcap.Net in http://pcapdotnet.codeplex.com


On Thu, Feb 25, 2010 at 12:39, Valpondi Hereza, Fabio <fabio.valpondi_hereza at siemens.com<mailto:fabio.valpondi_hereza at siemens.com>> wrote:
Hi,

I am programming a kind of bridge device, reading from one interface, and forwarding the frame through another interface. Also in the inverse way.
The frame capture using "pcap_loop" happens without problems (I print the frame contents as well as length for debugging purposes).

The problem is when I try to send the interface via the other interface. I use the following call for the pcap_sendpacket function:
pcap_sendpacket(iface2, pkt_data_iface1_2,sizeof(pkt_data_iface1_2));

iface2 is the outgoing interface
pkt_data_iface1_2 is the frame received on Interface 1 and being sent over Interface 2
sizeof(pkt_data_iface1_2) is the buffer size.

Only the first four bytes of the frame are sent. The device that uses wireshark to analyze the frames sent by my program, shows them as malformed.
I also tried for the size parameter sizeof(hear_iface1_2->caplen) or the pcap_inject function:  The result was the same.

My question is: does anybody know, why only the first four bytes are sent?


Thanks a lot for your help!

Best regards,
Fabio Valpondi

_______________________________________________
Winpcap-users mailing list
Winpcap-users at winpcap.org<mailto:Winpcap-users at winpcap.org>
https://www.winpcap.org/mailman/listinfo/winpcap-users


-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.winpcap.org/pipermail/winpcap-users/attachments/20100225/cf35e1ea/attachment.htm