patty/src/decode.c

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <unistd.h>

#include <patty/kiss.h>
#include <patty/ax25.h>

static void usage(int argc, char **argv, const char *message, ...) {
    if (message) {
        va_list args;

        va_start(args, message);
        vfprintf(stderr, message, args);
         fprintf(stderr, "\n");
        va_end(args);
    }

    fprintf(stderr, "usage: %s kiss.cap\n", argv[0]);

    exit(1);
}

static int callsign_fprint(FILE *stream, const patty_ax25_address *address) {
    fprintf(stream, "%s", address->callsign);

    if (address->ssid) {
        fprintf(stream, "/%d", address->ssid);
    }

    return 0;
}

static int address_fprint(FILE *stream, const patty_ax25_frame *frame) {
    int i;

    callsign_fprint(stream, &frame->src);
    fprintf(stream, " > ");
    callsign_fprint(stream, &frame->dest);

    for (i=0; i<frame->hops; i++) {
        fprintf(stream, " < ");
        callsign_fprint(stream, &frame->repeaters[i]);
    }

    return 0;
}

int main(int argc, char **argv) {
    patty_kiss_tnc *tnc;
    ssize_t len;
    void *data;
    int port;

    if (argc != 2) {
        usage(argc, argv, "No TNC device provided");
    }

    if ((tnc = patty_kiss_tnc_open(argv[1], 330)) == NULL) {
        perror("Unable to open TNC");

        exit(127);
    }

    while ((len = patty_kiss_tnc_recv(tnc, &data, &port)) > 0) {
        patty_ax25_frame frame;

        if (patty_ax25_frame_decode(&frame, data, len, PATTY_AX25_FRAME_NORMAL) < 0) {
            perror("Unable to decode frame");

            exit(127);
        }

        address_fprint(stderr, &frame);

        if (frame.type == PATTY_AX25_FRAME_INFO) {
            fprintf(stderr, " poll %d", PATTY_AX25_CONTROL_POLL(frame.control));
            fprintf(stderr, " ns %d",   PATTY_AX25_CONTROL_SEQ_SEND(frame.control));
            fprintf(stderr, " nr %d",   PATTY_AX25_CONTROL_SEQ_RECV(frame.control));
        }

        if (frame.payload) {
            fprintf(stderr, " proto %02x", frame.proto);
        }

        fprintf(stderr, " %ld bytes\n", len);
    }

    patty_kiss_tnc_close(tnc);

    return 0;
}