cosmopolitan/libc/dns/parseresolvconf.c

70 lines
3.4 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/alg/arraylist.internal.h"
#include "libc/dns/dns.h"
#include "libc/dns/resolvconf.h"
#include "libc/mem/mem.h"
#include "libc/runtime/runtime.h"
#include "libc/sock/sock.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/af.h"
#include "libc/sysv/consts/inaddr.h"
/**
* Parses /etc/resolv.conf file.
*
* The content of the file usually looks like this:
*
* nameserver 8.8.8.8
* nameserver 8.8.4.4
*
* @param resolv points to a ResolvConf object, which should be zero
* initialized by the caller; or if it already contains items,
* this function will append
* @param f is an open stream with file content
* @return number of nameservers appended, or -1 w/ errno
*/
int parseresolvconf(struct ResolvConf *resolv, struct FILE *f) {
/* TODO(jart): options ndots:5 */
int rc;
char *line;
size_t linesize;
struct sockaddr_in nameserver;
char *directive, *value, *tok, *comment;
rc = 0;
line = NULL;
linesize = 0;
nameserver.sin_family = AF_INET;
nameserver.sin_port = htons(DNS_PORT);
while (getline(&line, &linesize, f) != -1) {
if ((comment = strchr(line, '#'))) *comment = '\0';
if ((directive = strtok_r(line, " \t\r\n\v", &tok)) &&
(value = strtok_r(NULL, " \t\r\n\v", &tok))) {
if ((strcmp(directive, "nameserver") == 0 &&
inet_pton(AF_INET, value, &nameserver.sin_addr.s_addr) == 1)) {
if (append(&resolv->nameservers, &nameserver) != -1) ++rc;
}
}
}
free(line);
return rc | ferror(f);
}