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/* ISC license. */
#include <string.h>
#include <skalibs/bytestr.h>
#include <skalibs/sgetopt.h>
#include <skalibs/buffer.h>
#include <skalibs/fmtscan.h>
#include <skalibs/strerr2.h>
#include <skalibs/djbunix.h>
#include <skalibs/ip46.h>
#include <s6-dns/s6dns-constants.h>
#define USAGE "dnsfunnel-translate [ -i resolvconf ] [ -o cachelist ] [ -x ignoredip ]"
#define dieusage() strerr_dieusage(100, USAGE)
static size_t parse_nameservers (ip46 *list, char const *file, char const *ignore)
{
static char const zero[SKALIBS_IP_SIZE] = { 0 } ;
char buf[4096] ;
size_t n = 0, i = 0 ;
ssize_t len = openreadnclose(file, buf, 4095) ;
if (len < 0) strerr_diefu2sys(111, "open ", file) ;
buf[len++] = '\n' ;
while ((i < len) && (n < S6DNS_MAX_SERVERS))
{
size_t j = byte_chr(buf + i, len - i, '\n') ;
if ((i + j < len) && (j > 13U) && !memcmp("nameserver", buf + i, 10))
{
size_t k = 0 ;
while ((buf[i+10+k] == ' ') || (buf[i+10+k] == '\t')) k++ ;
if (k && ip46_scan(buf+i+10+k, list + n)
&& memcmp(list[n].ip, zero, SKALIBS_IP_SIZE)
&& (ip46_is6(list + n) || memcmp(list[n].ip, ignore, 4))
) n++ ;
}
i += j + 1 ;
}
return n ;
}
int main (int argc, char const *const *argv)
{
ip46 list[S6DNS_MAX_SERVERS] = { IP46_ZERO } ;
char const *resolvconf = "/etc/resolv.conf" ;
char const *cachelist = "/run/dnsfunnel/root/caches" ;
char ignore[4] = "\177\0\0\1" ;
size_t n ;
PROG = "dnsfunnel-translate" ;
{
subgetopt l = SUBGETOPT_ZERO ;
for (;;)
{
int opt = subgetopt_r(argc, argv, "i:o:x:", &l) ;
if (opt == -1) break ;
switch (opt)
{
case 'i' : resolvconf = l.arg ; break ;
case 'o' : cachelist = l.arg ; break ;
case 'x' : if (!ip4_scan(l.arg, ignore)) dieusage() ; break ;
default : dieusage() ;
}
}
argc -= l.ind ; argv += l.ind ;
}
n = parse_nameservers(list, resolvconf, ignore) ;
if (!n) strerr_dief2x(1, "no suitable cache address in ", resolvconf) ;
{
char buf[4096] ;
buffer b ;
int fd = openc_trunc(cachelist) ;
if (fd < 0) strerr_diefu2sys(111, "open ", cachelist) ;
buffer_init(&b, &buffer_write, fd, buf, 4096) ;
for (size_t i = 0 ; i < n ; i++)
{
char fmt[IP46_FMT] ;
size_t len = ip46_fmt(fmt, list + i) ;
fmt[len++] = '\n' ;
if (buffer_put(&b, fmt, len) < len)
strerr_diefu2sys(111, "write to ", cachelist) ;
}
if (!buffer_flush(&b))
strerr_diefu2sys(111, "write to ", cachelist) ;
}
return 0 ;
}
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