patty/src/ax25.c

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/select.h>

#include <patty/ax25.h>

int patty_ax25_pton(const char *callsign,
                    uint8_t ssid,
                    patty_ax25_addr *addr) {
    int i,
        end = 0;

    for (i=0; i<PATTY_AX25_CALLSIGN_LEN; i++) {
        if (callsign[i] == '\0') {
            if (i == 0) {
                errno = EINVAL;

                goto error_invalid_callsign;
            }

            end = 1;
        } else {
            if (!PATTY_AX25_ADDR_CHAR_VALID(callsign[i])) {
                errno = EINVAL;

                goto error_invalid_callsign;
            }
        }

        addr->callsign[i] = ((end? ' ': callsign[i]) & 0x7f) << 1;
    }

    addr->ssid = (ssid & 0x0f) << 1;

    return 0;

error_invalid_callsign:
    return -1;
}

int patty_ax25_ntop(const patty_ax25_addr *addr,
                    char *dest,
                    uint8_t *ssid,
                    size_t len) {
    int i, o, space = 0;

    if (addr == NULL || dest == NULL || ssid == NULL) {
        errno = EINVAL;

        goto error_invalid_args;
    }

    for (i=0, o=0; i<PATTY_AX25_CALLSIGN_LEN; i++) {
        uint8_t c;

        if (o == len) {
            break;
        }

        if (PATTY_AX25_ADDR_OCTET_LAST(addr->callsign[i])) {
            errno = EINVAL;

            goto error_invalid_args;
        }

        c = (addr->callsign[i] & 0xfe) >> 1;

        if (!PATTY_AX25_ADDR_CHAR_VALID(c)) {
            errno = EINVAL;

            goto error_invalid_args;
        } else if (c == ' ' && !space) {
            space = 1;
        } else if (c != ' ' && space) {
            errno = EINVAL;

            goto error_invalid_args;
        }

        dest[o++] = space? '\0': c;
    }

    dest[o] = '\0';

    *ssid = (addr->ssid & 0x1e) >> 1;

    return 0;

error_invalid_args:
    return -1;
}

static inline void hash_byte(uint32_t *hash, uint8_t c) {
    *hash += c;
    *hash += (*hash << 10);
    *hash ^= (*hash >>  6);
}

void patty_ax25_addr_hash(uint32_t *hash, const patty_ax25_addr *addr) {
    size_t i;

    for (i=0; i<PATTY_AX25_CALLSIGN_LEN; i++) {
        hash_byte(hash, addr->callsign[i] >> 1);
    }

    hash_byte(hash, PATTY_AX25_ADDR_SSID_NUMBER(addr->ssid));
}