文章资料取自我的禅宗频道。
使用TShark分析RTP数据包
在上一篇文章中，我们组装了一个由发生器和音频信号检测器组成的远程控制电路，它们之间的通信是使用RTP流进行的。
RTP-. RTP- .
, RTP, , mstest6.c , , , mstest_common.c, include:
#include <mediastreamer2/msfilter.h>
#include <mediastreamer2/msticker.h>
#include <mediastreamer2/msrtp.h>
#include <ortp/rtpsession.h>
#include <ortp/payloadtype.h>
define PCMU 0
void register_payloads(void)
{
rtp_profile_set_payload (&av_profile, PCMU, &payload_type_pcm8000);
}
static RtpSession *create_rtpsession (int loc_rtp_port, int loc_rtcp_port, bool_t ipv6, RtpSessionMode mode)
{
RtpSession *rtpr; rtpr = rtp_session_new ((int) mode);
rtp_session_set_scheduling_mode (rtpr, 0);
rtp_session_set_blocking_mode (rtpr, 0);
rtp_session_enable_adaptive_jitter_compensation (rtpr, TRUE);
rtp_session_set_symmetric_rtp (rtpr, TRUE);
rtp_session_set_local_addr (rtpr, ipv6 ? "::" : "0.0.0.0", loc_rtp_port, loc_rtcp_port);
rtp_session_signal_connect (rtpr, "timestamp_jump", (RtpCallback) rtp_session_resync, 0);
rtp_session_signal_connect (rtpr, "ssrc_changed", (RtpCallback) rtp_session_resync, 0);
rtp_session_set_ssrc_changed_threshold (rtpr, 0);
rtp_session_set_send_payload_type(rtpr, PCMU);
rtp_session_enable_rtcp (rtpr, FALSE);
return rtpr;
}
:
#include <mediastreamer2/dtmfgen.h>
#include <mediastreamer2/msrtp.h>
#include "mstest_common.c"
int main()
{
ms_init();
MSFilter *voidsource = ms_filter_new(MS_VOID_SOURCE_ID);
MSFilter *dtmfgen = ms_filter_new(MS_DTMF_GEN_ID);
MSFilter *encoder = ms_filter_create_encoder("PCMU");
register_payloads();
RtpSession *tx_rtp_session = create_rtpsession (8010, 8011, FALSE, RTP_SESSION_SENDONLY);
rtp_session_set_remote_addr_and_port(tx_rtp_session,"127.0.0.1", 7010, 7011);
rtp_session_set_send_payload_type(tx_rtp_session, PCMU);
MSFilter *rtpsend = ms_filter_new(MS_RTP_SEND_ID);
ms_filter_call_method(rtpsend, MS_RTP_SEND_SET_SESSION, tx_rtp_session);
MSTicker *ticker_tx = ms_ticker_new();
ms_filter_link(voidsource, 0, dtmfgen, 0);
ms_filter_link(dtmfgen, 0, encoder, 0);
ms_filter_link(encoder, 0, rtpsend, 0);
ms_ticker_attach(ticker_tx, voidsource);
MSDtmfGenCustomTone dtmf_cfg;
dtmf_cfg.tone_name[0] = 0;
dtmf_cfg.duration = 1000;
dtmf_cfg.frequencies[0] = 440;
dtmf_cfg.frequencies[1] = 0;
dtmf_cfg.amplitude = 1.0;
dtmf_cfg.interval = 0.;
dtmf_cfg.repeat_count = 0.;
char key='9';
printf(" , .\n"
" 0.\n");
while(key != '0')
{
key = getchar();
if ((key >= 49) && (key <= 54))
{
printf(" : %c\n", key);
dtmf_cfg.frequencies[0] = 440 + 100*(key-49);
ms_filter_call_method(dtmfgen, MS_DTMF_GEN_PLAY_CUSTOM, (void*)&dtmf_cfg);
}
ms_usleep(20000);
}
}
, :
include <mediastreamer2/mssndcard.h>
include <mediastreamer2/mstonedetector.h>
include <mediastreamer2/msrtp.h>
include <mediastreamer2/mseventqueue.h>
include "mstest_common.c"
static void tone_detected_cb(void *data, MSFilter *f, unsigned int event_id,MSToneDetectorEvent *ev)
{
printf(" : %s\n", ev->tone_name);
}
int main()
{
ms_init();
MSSndCard *card_playback = ms_snd_card_manager_get_default_card(ms_snd_card_manager_get());
MSFilter *snd_card_write = ms_snd_card_create_writer(card_playback);
MSFilter *detector = ms_filter_new(MS_TONE_DETECTOR_ID);
ms_filter_call_method(detector, MS_TONE_DETECTOR_CLEAR_SCANS, 0);
ms_filter_set_notify_callback(detector, (MSFilterNotifyFunc)tone_detected_cb, NULL);
MSToneDetectorDef scan[6]=
{
{"V+",440, 100, 0.1},
{"V-",540, 100, 0.1},
{"C+",640, 100, 0.1},
{"C-",740, 100, 0.1},
{"ON",840, 100, 0.1},
{"OFF", 940, 100, 0.1}
};
int i;
for (i = 0; i < 6; i++)
{
ms_filter_call_method(detector, MS_TONE_DETECTOR_ADD_SCAN, &scan[i]);
}
MSFilter *decoder=ms_filter_create_decoder("PCMU");
register_payloads();
MSFilter *rtprecv = ms_filter_new(MS_RTP_RECV_ID);
RtpSession *rx_rtp_session = create_rtpsession (7010, 7011, FALSE, RTP_SESSION_RECVONLY);
ms_filter_call_method(rtprecv, MS_RTP_RECV_SET_SESSION, rx_rtp_session);
MSTicker *ticker_rx = ms_ticker_new();
ms_filter_link(rtprecv, 0, decoder, 0);
ms_filter_link(decoder, 0, detector, 0);
ms_filter_link(detector, 0, snd_card_write, 0);
ms_ticker_attach(ticker_rx, rtprecv);
char key='9';
printf( " 0.\n");
while(key != '0')
{
key = getchar();
ms_usleep(20000);
}
}
, , . — 1 6 , . . , — RTP- .
, Wireshrk — TShark. TShark , . Wireshark , Wireshark.
Wireshark, . TShark, VoIP , .
TShark :
sudo apt-get install tshark
, :
tshark --version
.
, tshark . loopback ( ), TShark -i lo:
sudo tshark -i lo
(, , ). , , . , , . Ctrl-C (8010): -f "udp port 8010". :
sudo tshark -i lo -f "udp port 8010"
( 10 ):
1 0.000000000 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
2 0.020059705 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
3 0.040044409 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
4 0.060057104 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
5 0.080082311 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
6 0.100597153 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
7 0.120122668 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
8 0.140204789 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
9 0.160719008 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
10 0.180673685 127.0.0.1 → 127.0.0.1 UDP 214 8010 → 7010 Len=172
, , , . , , . :
.
.
IP- IP- .
, UDP, RTP- UDP-.
.
.
, , RTP- 172 , , , UDP- 214 .
UDP-, TShark :
sudo tshark -i lo -f "udp port 8010" -P -V -O rtp -o rtp.heuristic_rtp:TRUE -x
结果，该程序的输出将得到充实-导致该程序包的内部内容的解密将被添加到每个事件中。为了更好地查看输出数据，您可以通过按Ctrl-C来停止TShark，或者通过将管道添加到tee程序中并在启动命令中添加文件名tee <filename>来将其输出复制到文件中：
sudo tshark -i lo -f "udp port 8010" -P -V -O rtp -o rtp.heuristic_rtp:TRUE -x | tee log.txt
现在让我们看一下文件中包含的内容，这是文件中的第一个包：
1 0.000000000 127.0.0.1 → 127.0.0.1 RTP 214 PT=ITU-T G.711 PCMU, SSRC=0x6B8B4567, Seq=58366, Time=355368720
Frame 1: 214 bytes on wire (1712 bits), 214 bytes captured (1712 bits) on interface 0
Ethernet II, Src: 00:00:00_00:00:00 (00:00:00:00:00:00), Dst: 00:00:00_00:00:00 (00:00:00:00:00:00)
Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1User Datagram Protocol, Src Port: 8010, Dst Port: 7010
Real-Time Transport Protocol [Stream setup by HEUR RT (frame 1)]
[Setup frame: 1]
[Setup Method: HEUR RT]
10.. .... = Version: RFC 1889 Version (2)
..0. .... = Padding: False
...0 .... = Extension: False
.... 0000 = Contributing source identifiers count: 0
0... .... = Marker: False
Payload type: ITU-T G.711 PCMU (0)
Sequence number: 58366 [Extended sequence number: 58366]
Timestamp: 355368720
Synchronization Source identifier: 0x6b8b4567 (1804289383)
Payload: ffffffffffffffffffffffffffffffffffffffffffffffff...
0000 00 00 00 00 00 00 00 00 00 00 00 00 08 00 45 00 ..............E.
0010 00 c8 3c 69 40 00 40 11 ff b9 7f 00 00 01 7f 00 ..<i@.@.........
0020 00 01 1f 4a 1b 62 00 b4 fe c7 80 00 e3 fe 15 2e ...J.b..........
0030 7f 10 6b 8b 45 67 ff ff ff ff ff ff ff ff ff ff ..k.Eg..........
0040 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
0050 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
0060 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
0070 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
0080 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
0090 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
00a0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
00b0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
00c0 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
00d0 ff ff ff ff ff ff ......
我们将把以下文章专门用于分析此清单中包含的信息，并且不可避免地我们将讨论RTP数据包的内部结构。