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nfqws2: support mixed compressed+uncomressed DNS answers

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bol-van
2026-02-23 10:25:27 +03:00
parent d985bb316f
commit 61b0a70fa7
1 changed files with 34 additions and 20 deletions
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54
nfq2/desync.c
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@@ -1674,6 +1674,32 @@ static const uint8_t *dns_extract_name(const uint8_t *a, const uint8_t *b, const
name[nl] = 0;
return bptr ? a+2 : p+1;
}
static bool dns_skip_name(const uint8_t **a, size_t *len)
{
// 11 higher bits indicate pointer
// lazy skip name. mixed compressed/uncompressed names are supported
for(;;)
{
if (*len<2) return false;
if ((**a & 0xC0)==0xC0)
{
// pointer is the end
(*a)+=2; (*len)-=2;
break;
}
if (!**a)
{
// zero length is the end
(*a)++; (*len)--;
break;
}
if (*len<(**a+1)) return false;
*len-=**a+1;
*a+=**a+1;
}
return true;
}
static bool feed_dns_response(const uint8_t *a, size_t len)
{
if (!params.cache_hostname) return true;
@@ -1686,7 +1712,12 @@ static bool feed_dns_response(const uint8_t *a, size_t len)
size_t nl;
char name[256] = "";
if (!qcount || !acount || len<12 || !(a[2]&0x80)) return false;
if (!qcount || len<12 || !(a[2]&0x80)) return false;
if (!acount)
{
DLOG("skipping DNS response without answer\n");
return false;
}
a+=12; len-=12;
for(k=0,*name = 0 ; k<qcount ; k++)
{
@@ -1712,25 +1743,8 @@ static bool feed_dns_response(const uint8_t *a, size_t len)
if (!*name) return false;
for(k=0;k<acount;k++)
{
if (len<12) return false;
// 11 higher bits indicate pointer
if ((*a & 0xC0)==0xC0)
{
a+=2; len-=2;
}
else
{
// skip full name
while(*a)
{
// we do not support mixed names
if ((*a & 0xC0)==0xC0 || len<(*a + 11)) return false;
len-=*a+1;
a+=*a+1;
}
a++; len--;
}
if (!dns_skip_name(&a,&len)) return false;
if (len<10) return false;
dlen = a[8]<<8 | a[9];
if (len<(dlen+10)) return false;
if (a[2]==0 && a[3]==1) // IN class