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dns_rcrw.c
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dns_rcrw.c
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#include <unistd.h>
#include "taia.h"
#include "env.h"
#include "byte.h"
#include "str.h"
#include "openreadclose.h"
#include "dns.h"
static stralloc data = { 0, 0, 0 };
static int init(stralloc *rules)
{
char host[256];
const char *x;
int i;
int j;
int k;
if (!stralloc_copys(rules,"")) return -1;
x = env_get("DNSREWRITEFILE");
if (!x) x = "/etc/dnsrewrite";
i = openreadclose(x,&data,64);
if (i == -1) return -1;
if (i) {
if (!stralloc_append(&data,"\n")) return -1;
i = 0;
for (j = 0; (unsigned)j < data.len;++j)
if (data.s[j] == '\n') {
if (!stralloc_catb(rules,data.s + i,j - i)) return -1;
while (rules->len) {
if (rules->s[rules->len - 1] != ' ')
if (rules->s[rules->len - 1] != '\t')
if (rules->s[rules->len - 1] != '\r')
break;
--rules->len;
}
if (!stralloc_0(rules)) return -1;
i = j + 1;
}
return 0;
}
x = env_get("LOCALDOMAIN");
if (x) {
if (!stralloc_copys(&data,x)) return -1;
if (!stralloc_append(&data," ")) return -1;
if (!stralloc_copys(rules,"?:")) return -1;
i = 0;
for (j = 0; (unsigned)j < data.len;++j)
if (data.s[j] == ' ') {
if (!stralloc_cats(rules,"+.")) return -1;
if (!stralloc_catb(rules,data.s + i,j - i)) return -1;
i = j + 1;
}
if (!stralloc_0(rules)) return -1;
if (!stralloc_cats(rules,"*.:")) return -1;
if (!stralloc_0(rules)) return -1;
return 0;
}
i = openreadclose("/etc/resolv.conf",&data,64);
if (i == -1) return -1;
if (i) {
if (!stralloc_append(&data,"\n")) return -1;
i = 0;
for (j = 0; (unsigned)j < data.len;++j)
if (data.s[j] == '\n') {
if (byte_equal("search ",7,data.s + i) || byte_equal("search\t",7,data.s + i) || byte_equal("domain ",7,data.s + i) || byte_equal("domain\t",7,data.s + i)) {
if (!stralloc_copys(rules,"?:")) return -1;
i += 7;
while (i < j) {
k = byte_chr(data.s + i,j - i,' ');
k = byte_chr(data.s + i,k,'\t');
if (!k) { ++i; continue; }
if (!stralloc_cats(rules,"+.")) return -1;
if (!stralloc_catb(rules,data.s + i,k)) return -1;
i += k;
}
if (!stralloc_0(rules)) return -1;
if (!stralloc_cats(rules,"*.:")) return -1;
if (!stralloc_0(rules)) return -1;
return 0;
}
i = j + 1;
}
}
host[0] = 0;
if (gethostname(host,sizeof host) == -1) return -1;
host[(sizeof host) - 1] = 0;
i = str_chr(host,'.');
if (host[i]) {
if (!stralloc_copys(rules,"?:")) return -1;
if (!stralloc_cats(rules,host + i)) return -1;
if (!stralloc_0(rules)) return -1;
}
if (!stralloc_cats(rules,"*.:")) return -1;
if (!stralloc_0(rules)) return -1;
return 0;
}
static int ok = 0;
static unsigned int uses;
static struct taia deadline;
static stralloc rules = { 0, 0, 0 }; /* defined if ok */
int dns_resolvconfrewrite(stralloc *out)
{
struct taia now;
taia_now(&now);
if (taia_less(&deadline,&now)) ok = 0;
if (!uses) ok = 0;
if (!ok) {
if (init(&rules) == -1) return -1;
taia_uint(&deadline,600);
taia_add(&deadline,&now,&deadline);
uses = 10000;
ok = 1;
}
--uses;
if (!stralloc_copy(out,&rules)) return -1;
return 0;
}