[fpc-pascal] Help Reading SIP Messages.

lloyd thomas lloydie.t at googlemail.com
Wed Jan 6 12:30:20 CET 2010


Well I have made a start using someone elese libpcap inplementation, but
have bump into my first issue and because of my lack of skill I am not sure
how to code round it. Any Ideas?
I get the following errors

PlibCap\Pcap.pas(207,13) Error: Illegal qualifier
PlibCap\Pcap.pas(207,13) Hint: may be pointer dereference is missing
PlibCap\Pcap.pas(207,13) Fatal: Syntax error, "THEN" expected but
"identifier ADAPTER" found

In this section (so far)
     procedure CleanUp;
     begin
       if P.Adapter <> nil then PacketCloseAdapter(P.adapter); //error here
       if P.buffer<>nil then FreeMem(P.buffer,PcapBufSize); //but suspect I
would get one here as well
       Freemem(P,SizeOf(Tpcap));
     end,

(which I think has something to do with this)
type
  TWinVersion = (wv_WinS,
                 wv_Win9x,              //Added by Lars Peter Christiansen.
                 wv_WinNT,              //Eases the process of determing the
                 wv_Win2000,             //platform and do proper
instructions
                 wv_WinXP,               //I.e : Char vs. WideChar issue
                 wv_Unknown );



  PPcap_Stat = ^TPcap_stat;
  Tpcap_stat = record
    ps_recv,                          //* number of packets received */
    ps_drop,                         //* number of packets dropped */
    ps_ifdrop : LongWord;                //* drops by interface not
supported */
  end;

  TPcap_sf = record                      // Save file for offline reading.
    rfile : HFILE;
    swapped:integer;
    version_major : integer;
    Version_Minor : integer;
    base : Pointer;
  end;

  TPcap_md = record
    Stat : TPcap_stat;
    use_bpf : integer;
    TotPkts  : LongWord;               // Can owerflow after 79hours on
ethernet
    TotAccepted:LongWord;              // accepted by filter/sniffer
    TotDrops : LongWord;               // dropped packets
    TotMissed: Longword;               // missed by i/f during this run
    OrigMissed:LongWord;               // missed by i/f before this run
  end;

  PPcap_PktHdr = ^Tpcap_pkthdr;        // Wrapped Drivers packetHeader
  TPcap_pkthdr = record
    ts     : TUnixTimeVal;             // Time of capture
    CapLen,                            // captured length
    Len    : Integer;                  // actual length of packet
  end;

  PPcap = ^TPcap;                      // THE MAIN INTERFACE HANDLE
  TPcap = record                       // used with allmost all Pcap calls.
    Adapter:Padapter;
    Packet :PPacket;                   // Global Driver packet. kind of a
buffer
    snapshot:integer;
    linktype:integer;                  // Type and speed of net
    tzoff   :integer;                   // timezone offset
    offset  :integer;
    sf      :Tpcap_sf;                 // Save file
    md      :Tpcap_md;                 // Diagnostics
    //READ BUFFER
    bufsize :integer;
    buffer  :Pointer; //*u_char
    bp      :Pointer; //*u_char
    cc      :integer;
    //Place holder for pcap_next().
    pkt     :Pointer; //*U_char
    //Placeholder for filter code if bpf not in kernel.
    fcode   :Tbpf_program;
    errbuf  : array [0..PCAP_ERRBUF_SIZE-1] of char;  //Last error message
  end;


2010/1/5 ik <idokan at gmail.com>

> use libpcap (and bind it to FPC and share with us all :)) and then you can
> sniff packets (that's the easiest way I know).
>
>
> Ido
> http://ik.homelinux.org/
>
>
> On Tue, Jan 5, 2010 at 16:48, lloyd thomas <lloydie.t at googlemail.com>wrote:
>
>> Also came across this which uses pcap, but seems to be delphi only
>> http://www.magsys.co.uk/delphi/magmonsock.asp
>>
>> is there something similar for fpc?
>>
>> 2010/1/5 lloyd thomas <lloydie.t at googlemail.com>
>>
>> OK. I wish to monitor and record calls between a SIP endpoint and SIP
>>> Gateway. At the moment I am doing that by connecting the SIP endpoint and my
>>> machine to an ethernet hub so that I can see all the traffic.
>>> In the first instance I just need to correctly capture, read and
>>> interprete the SIP messages so that I can make an informed decision which
>>> RDP packets to capture.
>>>
>>> Then I suppose I will have an even harder task capturing the RDP packets
>>> and joining both legs together (my coding skills is not great)!
>>>
>>> Lloydie T
>>>
>>> 2010/1/5 ik <idokan at gmail.com>
>>>
>>> Hello,
>>>>
>>>> SIP first of all uses UDP most of the times (and rarely TCP) .
>>>> It only create a tunnel that other protocols such as RDP and SDP are
>>>> going inside.
>>>>
>>>> Can you explain a bit more what exactly do you wish to implement (i'm
>>>> not sure that I understand) ?
>>>>
>>>> Ido
>>>>
>>>> http://ik.homelinux.org/
>>>>
>>>>
>>>> On Tue, Jan 5, 2010 at 15:08, lloyd thomas <lloydie.t at googlemail.com>wrote:
>>>>
>>>>> Please forgive my ignorance regarding the project I am about to embark
>>>>> on.
>>>>> Need some advice on Lnet and capturing SIP RTP data to file. In the
>>>>> first instance I just need to work with the sip messages. I believe the SIP
>>>>> messages are similar to HTTP. I am using wireshark to understand how the SIP
>>>>> messages are processed, but I am not sure how to capture and read each frame
>>>>> (wireshark speak) using Lnet.
>>>>>
>>>>> (FYI:
>>>>> http://en.wikipedia.org/wiki/Session_Initiation_Protocol#SIP_network_elements
>>>>> )
>>>>>
>>>>> For instance the following is from frame 12 (935 bytes)
>>>>>
>>>>> ----------------------------------------------------------------------------------------------
>>>>> INVITE sip:1002 at 192.168.91.200 <sip%3A1002 at 192.168.91.200> SIP/2.0
>>>>> Via:SIP/2.0/UDP 192.168.91.190:5060;rport;branch=z9hG4bK83570061
>>>>> From:"Lloyd" <sip:1000 at 192.168.91.200 <sip%3A1000 at 192.168.91.200>
>>>>> >;tag=4b428357-2fa-1ec5d4e
>>>>> To:<sip:1002 at 192.168.91.200 <sip%3A1002 at 192.168.91.200>>
>>>>> Contact:"Lloyd" <sip:1000 at 192.168.91.190:5060;transport=UDP>
>>>>> Call-ID:83570000-4ce59f27 at 192.168.91.200<Call-ID%3A83570000-4ce59f27 at 192.168.91.200>
>>>>> Subject:sip phone call
>>>>> CSeq:2112045024 INVITE
>>>>> User-Agent:Mitel-5212-SIP-Phone 07.02.00.04 08000F24BEE5
>>>>> Allow:INVITE,ACK,CANCEL,BYE,OPTIONS,REFER,NOTIFY,PRACK,UPDATE
>>>>> Allow-Events:talk,hold,conference
>>>>> Supported:timer,100rel,replaces
>>>>> Session-Expires: 1800
>>>>> Min-SE: 90
>>>>> Max-Forwards:70
>>>>> Content-Type:application/sdp
>>>>> Content-Length:247
>>>>>
>>>>> v=0
>>>>> o=1000 1262650963 1262650962 IN IP4 192.168.91.190
>>>>> s=SIP Call
>>>>> c=IN IP4 192.168.91.190
>>>>> t=0 0
>>>>> a=sendrecv
>>>>> m=audio 20036 RTP/AVP 0 8 18 96
>>>>> a=rtpmap:0 PCMU/8000
>>>>> a=rtpmap:8 PCMA/8000
>>>>> a=rtpmap:18 G729/8000
>>>>> a=rtpmap:96 telephone-event/8000
>>>>>
>>>>> -----------------------------------------------------------------------------------------------
>>>>>
>>>>> I get a response from the sip server on frame 13 (371 bytes)
>>>>>
>>>>> ----------------------------------------------------------------------------------------------
>>>>> SIP/2.0 100 Trying
>>>>> Via: SIP/2.0/UDP 192.168.91.190:5060;rport=5060;branch=z9hG4bK83570061
>>>>> From: "Lloyd" <sip:1000 at 192.168.91.200 <sip%3A1000 at 192.168.91.200>
>>>>> >;tag=4b428357-2fa-1ec5d4e
>>>>> To: <sip:1002 at 192.168.91.200 <sip%3A1002 at 192.168.91.200>>
>>>>> Call-ID: 83570000-4ce59f27 at 192.168.91.200
>>>>> CSeq: 2112045024 INVITE
>>>>> User-Agent: FreeSWITCH-mod_sofia/1.0.trunk-15355M
>>>>> Content-Length: 0
>>>>>
>>>>> -----------------------------------------------------------------------------------------------
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> fpc-pascal maillist  -  fpc-pascal at lists.freepascal.org
>>>>> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
>>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> fpc-pascal maillist  -  fpc-pascal at lists.freepascal.org
>>>> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
>>>>
>>>
>>>
>>
>> _______________________________________________
>> fpc-pascal maillist  -  fpc-pascal at lists.freepascal.org
>> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
>>
>
>
> _______________________________________________
> fpc-pascal maillist  -  fpc-pascal at lists.freepascal.org
> http://lists.freepascal.org/mailman/listinfo/fpc-pascal
>
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