/*      $NetBSD: linkaddr.c,v 1.23 2022/04/19 20:32:15 rillig Exp $     */

/*-
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)linkaddr.c  8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: linkaddr.c,v 1.23 2022/04/19 20:32:15 rillig Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/socket.h>
#include <net/if_dl.h>

#include <assert.h>
#include <string.h>

/* States*/
#define NAMING  0
#define GOTONE  1
#define GOTTWO  2
#define RESET   3
/* Inputs */
#define DIGIT   (4*0)
#define END     (4*1)
#define DELIM   (4*2)
#define LETTER  (4*3)

void
link_addr(const char *addr, struct sockaddr_dl *sdl)
{
        char *cp = sdl->sdl_data;
        char *cplim = sdl->sdl_len + (char *)(void *)sdl;
        int byte = 0, state = NAMING;
        size_t newaddr = 0;     /* pacify gcc */

        _DIAGASSERT(addr != NULL);
        _DIAGASSERT(sdl != NULL);

        (void)memset(&sdl->sdl_family, 0, (size_t)sdl->sdl_len - 1);
        sdl->sdl_family = AF_LINK;
        do {
                state &= ~LETTER;
                if ((*addr >= '0') && (*addr <= '9')) {
                        newaddr = *addr - '0';
                } else if ((*addr >= 'a') && (*addr <= 'f')) {
                        newaddr = *addr - 'a' + 10;
                } else if ((*addr >= 'A') && (*addr <= 'F')) {
                        newaddr = *addr - 'A' + 10;
                } else if (*addr == 0) {
                        state |= END;
                } else if (state == NAMING &&
                           (((*addr >= 'A') && (*addr <= 'Z')) ||
                           ((*addr >= 'a') && (*addr <= 'z'))))
                        state |= LETTER;
                else
                        state |= DELIM;
                addr++;
                switch (state /* | INPUT */) {
                case NAMING | DIGIT:
                case NAMING | LETTER:
                        *cp++ = addr[-1];
                        continue;
                case NAMING | DELIM:
                        state = RESET;
                        _DIAGASSERT(__type_fit(uint8_t, cp - sdl->sdl_data));
                        sdl->sdl_nlen = (uint8_t)(cp - sdl->sdl_data);
                        continue;
                case GOTTWO | DIGIT:
                        *cp++ = byte;
                        /* FALLTHROUGH */
                case RESET | DIGIT:
                        state = GOTONE;
                        byte = (int)newaddr;
                        continue;
                case GOTONE | DIGIT:
                        state = GOTTWO;
                        byte = (int)newaddr + (byte << 4);
                        continue;
                default: /* | DELIM */
                        state = RESET;
                        *cp++ = byte;
                        byte = 0;
                        continue;
                case GOTONE | END:
                case GOTTWO | END:
                        *cp++ = byte;
                        /* FALLTHROUGH */
                case RESET | END:
                        break;
                }
                break;
        } while (cp < cplim); 

        _DIAGASSERT(__type_fit(uint8_t, cp - LLADDR(sdl)));
        sdl->sdl_alen = (uint8_t)(cp - LLADDR(sdl));
        newaddr = cp - (char *)(void *)sdl;
        if (newaddr > sizeof(*sdl)) {
                _DIAGASSERT(__type_fit(uint8_t, newaddr));
                sdl->sdl_len = (uint8_t)newaddr;
        }
        return;
}

static const char hexlist[16] = "0123456789abcdef";

char *
link_ntoa(const struct sockaddr_dl *sdl)
{
        static char obuf[64];
        char *out = obuf; 
        size_t i;
        const u_char *in = (const u_char *)CLLADDR(sdl);
        const u_char *inlim = in + sdl->sdl_alen;
        int firsttime = 1;

        _DIAGASSERT(sdl != NULL);

#define ADDC(ch) \
        do { \
                if (out >= obuf + sizeof(obuf) - 1) \
                        return obuf; \
                *out++ = (ch); \
        } while (0)

        /*
         * This is not needed on the first call, as the static
         * obuf wil be fully init'd to 0 by default.   But after
         * obuf has been returned to userspace the first time,
         * anything may have been written to it, so, let's be safe.
         *
         * (An alternative method would be to make ADDC() more
         *  complex:
         *      if (out < obuf + sizeof(obuf) - ((ch) != '\0'))
         *              *out++ = (ch);
         *  so it never returns, and the final ADDC(0) always works
         *  but that evaluates 'ch' twice, and is slower, so ...)
         */
        obuf[sizeof(obuf) - 1] = '\0';

        if (sdl->sdl_nlen) {
                if (sdl->sdl_nlen >= sizeof(obuf))
                        i = sizeof(obuf) - 1;
                else
                        i = sdl->sdl_nlen;
                (void)memcpy(obuf, sdl->sdl_data, i);
                out += i;
                if (sdl->sdl_alen)
                        ADDC(':');
        }
        while (in < inlim) {
                if (firsttime)
                        firsttime = 0;
                else
                        ADDC('.');
                i = *in++;
                if (i > 0xf) {
                        size_t j = i & 0xf;
                        i >>= 4;
                        ADDC(hexlist[i]);
                        ADDC(hexlist[j]);
                } else
                        ADDC(hexlist[i]);
        }
        ADDC('\0');
        return obuf;
}