FreeCalypso > hg > gsm-codec-lib
view pcap/rtp-cont-check.c @ 181:3a0ee08a3b9d
doc/EFR-rationale: typo fix
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Mon, 02 Jan 2023 20:09:07 +0000 |
parents | 693a0958a303 |
children | 10f11a2d4042 |
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/* * This program reads a pcap file, extracts packets belonging to a * particular RTP stream as identified by a source or destination * IP:port, and checks its continuity: verifies that the sequence * number always increments by 1 and that the timestamp always * increments by 160 units. Finally, this program prints out * the minimum and maximum observed capture time deltas between * successive packets of the stream. * * The codec can be anything, and this program can also be used to * check continuity of RTP streams coming from PSTN/SIP, but the * core assumption is that packets must arrive every 20 ms, with * the timestamp field incrementing by 160 units each time. */ #include <sys/types.h> #include <sys/socket.h> #include <sys/time.h> #include <netinet/in.h> #include <arpa/inet.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <strings.h> #include <pcap/pcap.h> static pcap_t *pcap; static in_addr_t match_ip_addr; static u_short match_udp_port; static unsigned iphdr_addr_offset, udphdr_port_offset; static unsigned link_hdr_len, ethertype_offset; static int stream_init_flag, deltat_init_flag; static unsigned last_seq, last_tstamp, stream_ssrc; static struct timeval last_pkt_time; static unsigned deltat_min, deltat_max; static void check_dl_type() { int dltype; dltype = pcap_datalink(pcap); switch (dltype) { case DLT_EN10MB: link_hdr_len = 14; ethertype_offset = 12; break; case DLT_RAW: link_hdr_len = 0; break; case DLT_LINUX_SLL: link_hdr_len = 16; ethertype_offset = 14; break; default: fprintf(stderr, "error: unsupported data link type %d\n", dltype); exit(1); } } static void rtp_stream_logic(rtp_hdr, pkt_idx, pkt_time) u_char *rtp_hdr; unsigned pkt_idx; struct timeval *pkt_time; { unsigned cur_seq, cur_tstamp, cur_ssrc; struct timeval deltat; cur_seq = (rtp_hdr[2] << 8) | rtp_hdr[3]; cur_tstamp = (rtp_hdr[4] << 24) | (rtp_hdr[5] << 16) | (rtp_hdr[6] << 8) | rtp_hdr[7]; cur_ssrc = (rtp_hdr[8] << 24) | (rtp_hdr[9] << 16) | (rtp_hdr[10] << 8) | rtp_hdr[11]; if (stream_init_flag) { if (cur_ssrc != stream_ssrc) { fprintf(stderr, "error in packet #%u: SSRC change from 0x%08X to 0x%08X\n", pkt_idx, stream_ssrc, cur_ssrc); exit(1); } if (cur_seq != last_seq + 1) { fprintf(stderr, "error in packet #%u: seq break from 0x%04X to 0x%04X\n", pkt_idx, last_seq, cur_seq); exit(1); } if (cur_tstamp != last_tstamp + 160) { fprintf(stderr, "error in packet #%u: timestamp break from 0x%08X to 0x%08X\n", pkt_idx, last_tstamp, cur_tstamp); exit(1); } if (timercmp(pkt_time, &last_pkt_time, <)) { fprintf(stderr, "packet #%u timing error: Rx time goes backward\n", pkt_idx); exit(1); } timersub(pkt_time, &last_pkt_time, &deltat); if (deltat.tv_sec) { fprintf(stderr, "packet #%u timing error: Rx time gap >= 1 s\n", pkt_idx); exit(1); } if (deltat_init_flag) { if (deltat.tv_usec < deltat_min) deltat_min = deltat.tv_usec; if (deltat.tv_usec > deltat_max) deltat_max = deltat.tv_usec; } else { deltat_min = deltat.tv_usec; deltat_max = deltat.tv_usec; deltat_init_flag = 1; } } else { stream_init_flag = 1; stream_ssrc = cur_ssrc; } last_seq = cur_seq; last_tstamp = cur_tstamp; bcopy(pkt_time, &last_pkt_time, sizeof(struct timeval)); } static void process_packet(pkt, caplen, pkt_idx, pkt_time) u_char *pkt; unsigned caplen, pkt_idx; struct timeval *pkt_time; { unsigned udplen; if (caplen < link_hdr_len + 28) return; if (link_hdr_len) { if (pkt[ethertype_offset] != 0x08) return; if (pkt[ethertype_offset+1] != 0x00) return; pkt += link_hdr_len; caplen -= link_hdr_len; } /* check IP header */ if (pkt[0] != 0x45) return; if (pkt[9] != 17) /* UDP */ return; if (bcmp(pkt + iphdr_addr_offset, &match_ip_addr, 4)) return; /* check UDP header */ if (bcmp(pkt + 20 + udphdr_port_offset, &match_udp_port, 2)) return; /* it is our target - now scrutinize it */ udplen = (pkt[24] << 8) | pkt[25]; if (caplen < udplen + 20) { fprintf(stderr, "error: packet #%u is truncated in the capture\n", pkt_idx); exit(1); } if (udplen < 20) { fprintf(stderr, "error in packet #%u: UDP length is too short for RTP header\n", pkt_idx); exit(1); } if (pkt[28] != 0x80) { fprintf(stderr, "error in packet #%u: unsupported RTP header structure\n", pkt_idx); exit(1); } rtp_stream_logic(pkt + 28, pkt_idx, pkt_time); } main(argc, argv) char **argv; { char errbuf[PCAP_ERRBUF_SIZE]; u_char *pkt; struct pcap_pkthdr pkthdr; unsigned pkt_idx; if (argc != 5) { fprintf(stderr, "usage: %s pcap-file src|dest ip-addr udp-port\n", argv[0]); exit(1); } pcap = pcap_open_offline(argv[1], errbuf); if (!pcap) { fprintf(stderr, "%s: %s\n", argv[1], errbuf); exit(1); } check_dl_type(); if (!strcmp(argv[2], "src")) { iphdr_addr_offset = 12; udphdr_port_offset = 0; } else if (!strcmp(argv[2], "dest")) { iphdr_addr_offset = 16; udphdr_port_offset = 2; } else { fprintf(stderr, "error: direction argument must be \"src\" or \"dest\"\n"); exit(1); } match_ip_addr = inet_addr(argv[3]); if (match_ip_addr == INADDR_NONE) { fprintf(stderr, "error: IP address argument is invalid\n"); exit(1); } match_udp_port = htons(strtoul(argv[4], 0, 0)); for (pkt_idx = 0; ; pkt_idx++) { pkt = pcap_next(pcap, &pkthdr); if (!pkt) break; process_packet(pkt, (unsigned) pkthdr.caplen, pkt_idx, &pkthdr.ts); } if (!stream_init_flag) { fprintf(stderr, "error: specified RTP stream not found\n"); exit(1); } if (!deltat_init_flag) { fprintf(stderr, "error: found only one matching packet\n"); exit(1); } printf("Minimum time delta: %u us\n", deltat_min); printf("Maximum time delta: %u us\n", deltat_max); exit(0); }