contrib/dhcpcd/src/common.c

   1 /* SPDX-License-Identifier: BSD-2-Clause */
   2 /*
   3  * dhcpcd - DHCP client daemon
   4  * Copyright (c) 2006-2023 Roy Marples <roy@marples.name>
   5  * All rights reserved
   6
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/stat.h>
  30 #include <sys/statvfs.h>
  31
  32 #include <ctype.h>
  33 #include <errno.h>
  34 #include <fcntl.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38
  39 #include "common.h"
  40 #include "dhcpcd.h"
  41 #include "if-options.h"
  42
  43 const char *
  44 hwaddr_ntoa(const void *hwaddr, size_t hwlen, char *buf, size_t buflen)
  45 {
  46         const unsigned char *hp, *ep;
  47         char *p;
  48
  49         /* Allow a hwlen of 0 to be an empty string. */
  50         if (buf == NULL || buflen == 0) {
  51                 errno = ENOBUFS;
  52                 return NULL;
  53         }
  54
  55         if (hwlen * 3 > buflen) {
  56                 /* We should still terminate the string just in case. */
  57                 buf[0] = '\0';
  58                 errno = ENOBUFS;
  59                 return NULL;
  60         }
  61
  62         hp = hwaddr;
  63         ep = hp + hwlen;
  64         p = buf;
  65         while (hp < ep) {
  66                 if (hp != hwaddr)
  67                         *p ++= ':';
  68                 p += snprintf(p, 3, "%.2x", *hp++);
  69         }
  70         *p ++= '\0';
  71         return buf;
  72 }
  73
  74 size_t
  75 hwaddr_aton(uint8_t *buffer, const char *addr)
  76 {
  77         char c[3];
  78         const char *p = addr;
  79         uint8_t *bp = buffer;
  80         size_t len = 0;
  81
  82         c[2] = '\0';
  83         while (*p != '\0') {
  84                 /* Skip separators */
  85                 c[0] = *p++;
  86                 switch (c[0]) {
  87                 case '\n':      /* long duid split on lines */
  88                 case ':':       /* typical mac address */
  89                 case '-':       /* uuid */
  90                         continue;
  91                 }
  92                 c[1] = *p++;
  93                 /* Ensure that digits are hex */
  94                 if (isxdigit((unsigned char)c[0]) == 0 ||
  95                     isxdigit((unsigned char)c[1]) == 0)
  96                 {
  97                         errno = EINVAL;
  98                         return 0;
  99                 }
 100                 /* We should have at least two entries 00:01 */
 101                 if (len == 0 && *p == '\0') {
 102                         errno = EINVAL;
 103                         return 0;
 104                 }
 105                 if (bp)
 106                         *bp++ = (uint8_t)strtol(c, NULL, 16);
 107                 len++;
 108         }
 109         return len;
 110 }
 111
 112 ssize_t
 113 readfile(const char *file, void *data, size_t len)
 114 {
 115         int fd;
 116         ssize_t bytes;
 117
 118         fd = open(file, O_RDONLY);
 119         if (fd == -1)
 120                 return -1;
 121         bytes = read(fd, data, len);
 122         close(fd);
 123         if ((size_t)bytes == len) {
 124                 errno = ENOBUFS;
 125                 return -1;
 126         }
 127         return bytes;
 128 }
 129
 130 ssize_t
 131 writefile(const char *file, mode_t mode, const void *data, size_t len)
 132 {
 133         int fd;
 134         ssize_t bytes;
 135
 136         fd = open(file, O_WRONLY | O_CREAT | O_TRUNC, mode);
 137         if (fd == -1)
 138                 return -1;
 139         bytes = write(fd, data, len);
 140         close(fd);
 141         return bytes;
 142 }
 143
 144 int
 145 filemtime(const char *file, time_t *time)
 146 {
 147         struct stat st;
 148
 149         if (stat(file, &st) == -1)
 150                 return -1;
 151         *time = st.st_mtime;
 152         return 0;
 153 }
 154
 155 /* Handy routine to read very long lines in text files.
 156  * This means we read the whole line and avoid any nasty buffer overflows.
 157  * We strip leading space and avoid comment lines, making the code that calls
 158  * us smaller. */
 159 char *
 160 get_line(char ** __restrict buf, ssize_t * __restrict buflen)
 161 {
 162         char *p, *c;
 163         bool quoted;
 164
 165         do {
 166                 p = *buf;
 167                 if (*buf == NULL)
 168                         return NULL;
 169                 c = memchr(*buf, '\n', (size_t)*buflen);
 170                 if (c == NULL) {
 171                         c = memchr(*buf, '\0', (size_t)*buflen);
 172                         if (c == NULL)
 173                                 return NULL;
 174                         *buflen = c - *buf;
 175                         *buf = NULL;
 176                 } else {
 177                         *c++ = '\0';
 178                         *buflen -= c - *buf;
 179                         *buf = c;
 180                 }
 181                 for (; *p == ' ' || *p == '\t'; p++)
 182                         ;
 183         } while (*p == '\0' || *p == '\n' || *p == '#' || *p == ';');
 184
 185         /* Strip embedded comments unless in a quoted string or escaped */
 186         quoted = false;
 187         for (c = p; *c != '\0'; c++) {
 188                 if (*c == '\\') {
 189                         c++; /* escaped */
 190                         continue;
 191                 }
 192                 if (*c == '"')
 193                         quoted = !quoted;
 194                 else if (*c == '#' && !quoted) {
 195                         *c = '\0';
 196                         break;
 197                 }
 198         }
 199         return p;
 200 }
 201
 202
 203 int
 204 is_root_local(void)
 205 {
 206 #ifdef ST_LOCAL
 207         struct statvfs vfs;
 208
 209         if (statvfs("/", &vfs) == -1)
 210                 return -1;
 211         return vfs.f_flag & ST_LOCAL ? 1 : 0;
 212 #else
 213         errno = ENOTSUP;
 214         return -1;
 215 #endif
 216 }