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/* ISC license. */
#include <errno.h>
#include <stdint.h>
#include <string.h>
#include <skalibs/uint16.h>
#include <skalibs/uint32.h>
#include <skalibs/error.h>
#include <skalibs/strerr2.h>
#include <skalibs/stralloc.h>
#include <skalibs/socket.h>
#include <s6-dns/s6dns-constants.h>
#include <s6-dns/s6dns-message.h>
#include "dnsfunneld.h"
static stralloc q = STRALLOC_ZERO ;
static size_t head = 0 ;
size_t dfanswer_pending ()
{
return q.len - head ;
}
static void dfanswer_push (char const *s, size_t len, uint32_t ip, uint16_t port)
{
if (len > 512)
{
if (verbosity)
strerr_warnw1x("answer too big, dropping - enable truncation to avoid this") ;
}
else
{
if (!stralloc_readyplus(&q, len + 8)) strerr_diefu1sys(111, "queue answer to client") ;
uint32_pack_big(q.s + q.len, ip) ; q.len += 4 ;
uint16_pack_big(q.s + q.len, port) ; q.len += 2 ;
uint16_pack_big(q.s + q.len, len) ; q.len += 2 ;
memcpy(q.s + q.len, s, len) ; q.len += len ;
}
}
int dfanswer_flush ()
{
while (dfanswer_pending())
{
uint16_t port, len ;
uint16_unpack_big(q.s + head + 4, &port) ;
uint16_unpack_big(q.s + head + 6, &len) ;
if (socket_send4(0, q.s + head + 8, len, q.s + head, port) < 0)
return error_isagain(errno) ? (errno = 0, 0) : -1 ;
head += len + 8 ;
if ((q.len - head) >> 2 <= q.len)
{
memmove(q.s, q.s + head, q.len - head) ;
q.len -= head ;
head = 0 ;
}
}
return 1 ;
}
static void switchaux (char *buf, uint16_t len)
{
uint16_t qtype ;
uint16_unpack_big(buf + len - 4, &qtype) ;
switch (qtype)
{
case S6DNS_T_A : qtype = S6DNS_T_AAAA ; break ;
case S6DNS_T_AAAA : qtype = S6DNS_T_A ; break ;
default : strerr_dief1x(101, "can't happen: invalid qtype in auxiliary query") ;
}
uint16_pack_big(buf + len - 4, qtype) ;
}
void dfanswer_fail (dfquery_t const *q, int isaux)
{
char buf[512] ;
s6dns_message_header_t hdr ;
uint16_t len ;
uint16_unpack_big(q->dt.sa.s, &len) ;
memcpy(buf, q->dt.sa.s + 2, len) ;
s6dns_message_header_unpack(buf, &hdr) ;
hdr.id = q->id ;
hdr.qr = 1 ;
hdr.aa = 0 ;
hdr.tc = 0 ;
hdr.rd = 1 ;
hdr.ra = 1 ;
hdr.z = 0 ;
hdr.rcode = 2 ; /* servfail */
s6dns_message_header_pack(buf, &hdr) ;
if (isaux) switchaux(buf, len) ;
dfanswer_push(buf, len, q->ip, q->port) ;
}
void dfanswer_nxdomain (dfquery_t const *q, int isaux)
{
char buf[512] ;
s6dns_message_header_t hdr ;
uint16_t len ;
uint16_unpack_big(q->dt.sa.s, &len) ;
memcpy(buf, q->dt.sa.s + 2, len) ;
s6dns_message_header_unpack(buf, &hdr) ;
hdr.id = q->id ;
hdr.qr = 1 ;
hdr.aa = 1 ;
hdr.tc = 0 ;
hdr.rd = 1 ;
hdr.ra = 1 ;
hdr.z = 0 ;
hdr.rcode = 3 ; /* nxdomain */
s6dns_message_header_pack(buf, &hdr) ;
if (isaux) switchaux(buf, len) ;
dfanswer_push(buf, len, q->ip, q->port) ;
}
void dfanswer_nodata (dfquery_t const *q, int isaux)
{
char buf[512] ;
s6dns_message_header_t hdr ;
uint16_t len ;
uint16_unpack_big(q->dt.sa.s, &len) ;
memcpy(buf, q->dt.sa.s + 2, len) ;
s6dns_message_header_unpack(buf, &hdr) ;
hdr.id = q->id ;
hdr.qr = 1 ;
hdr.aa = 1 ;
hdr.tc = 0 ;
hdr.rd = 1 ;
hdr.ra = 1 ;
hdr.z = 0 ;
hdr.rcode = 0 ; /* success */
s6dns_message_header_pack(buf, &hdr) ;
if (isaux) switchaux(buf, len) ;
dfanswer_push(buf, len, q->ip, q->port) ;
}
void dfanswer_pass (dfquery_t const *q, char *s, unsigned int len)
{
s6dns_message_header_t hdr ;
s6dns_message_header_unpack(s, &hdr) ;
hdr.id = q->id ;
s6dns_message_header_pack(s, &hdr) ;
dfanswer_push(s, len, q->ip, q->port) ;
}
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