/*-
 * 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.
 *
 * @(#)linkaddr.c       8.1 (Berkeley) 6/4/93
 * $FreeBSD: head/lib/libc/net/linkaddr.c 309688 2016-12-07 23:18:00Z glebius $
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_dl.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 *)sdl;
        int byte = 0, state = NAMING, new;

        bzero((char *)&sdl->sdl_family, sdl->sdl_len - 1);
        sdl->sdl_family = AF_LINK;
        do {
                state &= ~LETTER;
                if ((*addr >= '0') && (*addr <= '9')) {
                        new = *addr - '0';
                } else if ((*addr >= 'a') && (*addr <= 'f')) {
                        new = *addr - 'a' + 10;
                } else if ((*addr >= 'A') && (*addr <= 'F')) {
                        new = *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;
                        sdl->sdl_nlen = cp - sdl->sdl_data;
                        continue;
                case GOTTWO | DIGIT:
                        *cp++ = byte;
                        /* FALLTHROUGH */
                case RESET | DIGIT:
                        state = GOTONE;
                        byte = new;
                        continue;
                case GOTONE | DIGIT:
                        state = GOTTWO;
                        byte = new + (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);
        sdl->sdl_alen = cp - LLADDR(sdl);
        new = cp - (char *)sdl;
        if (new > sizeof(*sdl))
                sdl->sdl_len = new;
        return;
}

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

char *
link_ntoa(const struct sockaddr_dl *sdl)
{
        static char obuf[64];
        _Static_assert(sizeof(obuf) >= IFNAMSIZ + 20, "obuf is too small");
        char *out;
        const u_char *in, *inlim;
        int namelen, i, rem;

        namelen = (sdl->sdl_nlen <= IFNAMSIZ) ? sdl->sdl_nlen : IFNAMSIZ;

        out = obuf;
        rem = sizeof(obuf);
        if (namelen > 0) {
                bcopy(sdl->sdl_data, out, namelen);
                out += namelen;
                rem -= namelen;
                if (sdl->sdl_alen > 0) {
                        *out++ = ':';
                        rem--;
                }
        }

        in = (const u_char *)sdl->sdl_data + sdl->sdl_nlen;
        inlim = in + sdl->sdl_alen;

        while (in < inlim && rem > 1) {
                if (in != (const u_char *)sdl->sdl_data + sdl->sdl_nlen) {
                        *out++ = '.';
                        rem--;
                }
                i = *in++;
                if (i > 0xf) {
                        if (rem < 3)
                                break;
                        *out++ = hexlist[i >> 4];
                        *out++ = hexlist[i & 0xf];
                        rem -= 2;
                } else {
                        if (rem < 2)
                                break;
                        *out++ = hexlist[i];
                        rem--;
                }
        }
        *out = 0;
        return (obuf);
}