# HG changeset patch # User Mychaela Falconia # Date 1672089840 0 # Node ID b9af126bfddb3d64cde051685b89a26f0074eac3 # Parent 0c965c3c5e6e641cb6b94fcf10f38c4a6edb4d0e rtp-cont-check utility written diff -r 0c965c3c5e6e -r b9af126bfddb .hgignore --- a/.hgignore Sun Dec 25 09:53:04 2022 +0000 +++ b/.hgignore Mon Dec 26 21:24:00 2022 +0000 @@ -40,4 +40,5 @@ ^miscutil/pcm16-raw2wav$ ^miscutil/pcm16-wav2raw$ +^pcap/rtp-cont-check$ ^pcap/rtp-gsmfr-extr$ diff -r 0c965c3c5e6e -r b9af126bfddb pcap/Makefile --- a/pcap/Makefile Sun Dec 25 09:53:04 2022 +0000 +++ b/pcap/Makefile Mon Dec 26 21:24:00 2022 +0000 @@ -1,10 +1,13 @@ CC= gcc CFLAGS= -O2 -PROGS= rtp-gsmfr-extr +PROGS= rtp-cont-check rtp-gsmfr-extr INSTBIN=/opt/freecalypso/bin all: ${PROGS} +rtp-cont-check: rtp-cont-check.c + ${CC} ${CFLAGS} -o $@ $@.c -lpcap + rtp-gsmfr-extr: rtp-gsmfr-extr.c ${CC} ${CFLAGS} -o $@ $@.c -lpcap diff -r 0c965c3c5e6e -r b9af126bfddb pcap/rtp-cont-check.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/pcap/rtp-cont-check.c Mon Dec 26 21:24:00 2022 +0000 @@ -0,0 +1,231 @@ +/* + * 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 all sequence + * numbers and timestamps increase monotonously without breaks, + * and that the time delta between each consecutive pair of packets + * is within GSM TCH multiframe jitter bounds of 20 ms. + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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; +static unsigned last_seq, last_tstamp, stream_ssrc; +static struct timeval last_pkt_time; + +/* usec jitter thresholds around 20 ms ideal */ +#define DELTAT_MIN 18450 +#define DELTAT_MAX 23090 + +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.tv_usec > DELTAT_MAX) { + fprintf(stderr, +"packet #%u timing error: Rx time delta of %u us is above max threshold\n", + pkt_idx, (unsigned) deltat.tv_usec); + exit(1); + } + if (deltat.tv_usec < DELTAT_MIN) { + fprintf(stderr, +"packet #%u timing error: Rx time delta of %u us is below min threshold\n", + pkt_idx, (unsigned) deltat.tv_usec); + exit(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); + } + exit(0); +}