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#include "taia.h"
#include "readclose.h"
#include "byte.h"
#include "ip.h"
#include "env.h"
#include "dnsresolv.h"
#include "socket_if.h"
/**
* @file dns_rcip.c
* @author djb, fefe, feh
* @ref ucspi-tcp
* @brief DNS receive for query
*/
static stralloc data = {0};
static stralloc ifname = {0};
static int init(char ip[QUERY_MAXIPLEN],uint32 sid[QUERY_MAXNS])
{
int i;
int j;
int k = 0;
int iplen = 0;
char *x;
char ip4[4];
/* Read (compactified) IPv4|v6 addresses of resolvers
Store them in array IP with fixed length :
ip(64) -> 16 IPv4 addresses (not used anymore)
ip(512) -> 16*2 IPv6 addresses (we use IPv4 mapped IPv6 addresses)
sid(32) -> the scope for the respective IPv6 or 0
*/
for (i = 0; i < QUERY_MAXNS; ++i) sid[i] = 0;
x = env_get("DNSCACHEIP");
if (x)
while (iplen <= 240 && *x != '\0') {
if (*x == ' ')
++x;
else
if ((i = ip6_ifscan(x,ip + iplen,&ifname))) {
if (ifname.len > 2) sid[k] = socket_getifidx(ifname.s);
iplen += 16; k++;
if (*(x += i) == '\0') break;
}
}
if (!iplen) {
i = openreadclose("/etc/resolv.conf",&data,64);
if (i == -1) return DNS_INT;
if (i) {
if (!stralloc_append(&data,"\n")) return DNS_MEM;
i = 0;
for (j = 0; j < data.len; ++j)
if (data.s[j] == '\n') {
if (byte_equal("nameserver ",11,data.s + i) || byte_equal("nameserver\t",11,data.s + i)) {
i += 10;
while ((data.s[i] == ' ') || (data.s[i] == '\t'))
i++;
if (iplen <= 240) {
data.s[j] = '\0'; /* ip6_ifscan needs terminated string on input */
if (ip4_scan(data.s + i,ip4)) {
if (byte_equal(ip4,4,"\0\0\0\0"))
byte_copy(ip4,4,"\177\0\0\1");
byte_copy(ip + iplen,12,V4mappedprefix);
byte_copy(ip + iplen + 12,4,ip4);
sid[k] = 0; iplen += 16; k++;
} else if (ip6_ifscan(data.s + i,ip + iplen,&ifname)) {
if (ifname.len > 2) sid[k] = socket_getifidx(ifname.s);
iplen += 16; k++;
}
}
}
i = j + 1;
}
}
}
if (!iplen) {
byte_copy(ip,16,"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1");
iplen = 16;
}
byte_zero(ip + iplen,QUERY_MAXIPLEN - iplen);
return 0;
}
static int ok = 0;
static unsigned int uses;
static struct taia deadline;
static char ip[QUERY_MAXIPLEN]; /* defined if ok */
static uint32 scopes[QUERY_MAXNS];
int dns_resolvconfip(char s[QUERY_MAXIPLEN],uint32 scope[QUERY_MAXNS])
{
struct taia now;
taia_now(&now);
if (taia_less(&deadline,&now)) ok = 0;
if (!uses) ok = 0;
if (!ok) {
if (init(ip,scopes) < 0) return DNS_INT;
taia_uint(&deadline,600);
taia_add(&deadline,&now,&deadline);
uses = 10000;
ok = 1;
}
--uses;
byte_copy(s,QUERY_MAXIPLEN,ip);
byte_copy(scope,128,scopes);
return 0;
}
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