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Merge pull request #27

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5eca8e2 Fix negative responses (Peter Todd)
This commit is contained in:
Pieter Wuille 2015-07-29 14:56:56 +02:00
commit 5b36c248f5
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GPG key ID: 57896D2FF8F0B657
1 changed files with 27 additions and 13 deletions
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dns.c
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@ -287,18 +287,23 @@ ssize_t static dnshandle(dns_opt_t *opt, const unsigned char *inbuf, size_t insi
unsigned char *outpos = outbuf+(inpos-inbuf);
unsigned char *outend = outbuf + BUFLEN;
// printf("DNS: Request host='%s' type=%i class=%i\n", name, typ, cls);
// printf("DNS: Request host='%s' type=%i class=%i\n", name, typ, cls);
// calculate size of authority section
// calculate max size of authority section
int auth_size = 0;
int max_auth_size = 0;
if (!((typ == TYPE_NS || typ == QTYPE_ANY) && (cls == CLASS_IN || cls == QCLASS_ANY))) {
// authority section will be necessary
unsigned char *oldpos = outpos;
write_record_ns(&oldpos, outend, "", offset, CLASS_IN, 0, opt->ns);
auth_size = oldpos - outpos;
// printf("Authority section will claim %i bytes\n", auth_size);
// authority section will be necessary, either NS or SOA
unsigned char *newpos = outpos;
write_record_ns(&newpos, outend, "", offset, CLASS_IN, 0, opt->ns);
max_auth_size = newpos - outpos;
newpos = outpos;
write_record_soa(&newpos, outend, "", offset, CLASS_IN, opt->nsttl, opt->ns, opt->mbox, time(NULL), 604800, 86400, 2592000, 604800);
if (max_auth_size < newpos - outpos)
max_auth_size = newpos - outpos;
// printf("Authority section will claim %i bytes max\n", max_auth_size);
}
// Answer section
@ -307,14 +312,14 @@ ssize_t static dnshandle(dns_opt_t *opt, const unsigned char *inbuf, size_t insi
// NS records
if ((typ == TYPE_NS || typ == QTYPE_ANY) && (cls == CLASS_IN || cls == QCLASS_ANY)) {
int ret2 = write_record_ns(&outpos, outend - auth_size, "", offset, CLASS_IN, opt->nsttl, opt->ns);
int ret2 = write_record_ns(&outpos, outend - max_auth_size, "", offset, CLASS_IN, opt->nsttl, opt->ns);
// printf("wrote NS record: %i\n", ret2);
if (!ret2) { outbuf[7]++; have_ns++; }
}
// SOA records
if ((typ == TYPE_SOA || typ == QTYPE_ANY) && (cls == CLASS_IN || cls == QCLASS_ANY) && opt->mbox) {
int ret2 = write_record_soa(&outpos, outend - auth_size, "", offset, CLASS_IN, opt->nsttl, opt->ns, opt->mbox, time(NULL), 604800, 86400, 2592000, 604800);
int ret2 = write_record_soa(&outpos, outend - max_auth_size, "", offset, CLASS_IN, opt->nsttl, opt->ns, opt->mbox, time(NULL), 604800, 86400, 2592000, 604800);
// printf("wrote SOA record: %i\n", ret2);
if (!ret2) { outbuf[7]++; }
}
@ -327,9 +332,9 @@ ssize_t static dnshandle(dns_opt_t *opt, const unsigned char *inbuf, size_t insi
while (n < naddr) {
int ret = 1;
if (addr[n].v == 4)
ret = write_record_a(&outpos, outend - auth_size, "", offset, CLASS_IN, opt->datattl, &addr[n]);
ret = write_record_a(&outpos, outend - max_auth_size, "", offset, CLASS_IN, opt->datattl, &addr[n]);
else if (addr[n].v == 6)
ret = write_record_aaaa(&outpos, outend - auth_size, "", offset, CLASS_IN, opt->datattl, &addr[n]);
ret = write_record_aaaa(&outpos, outend - max_auth_size, "", offset, CLASS_IN, opt->datattl, &addr[n]);
// printf("wrote A record: %i\n", ret);
if (!ret) {
n++;
@ -340,13 +345,22 @@ ssize_t static dnshandle(dns_opt_t *opt, const unsigned char *inbuf, size_t insi
}
// Authority section
if (!have_ns) {
if (!have_ns && outbuf[7]) {
int ret2 = write_record_ns(&outpos, outend, "", offset, CLASS_IN, opt->nsttl, opt->ns);
// printf("wrote NS record: %i\n", ret2);
if (!ret2) {
outbuf[9]++;
}
}
else if (!outbuf[7]) {
// Didn't include any answers, so reply with SOA as this is a negative
// response. If we replied with NS above we'd create a bad horizontal
// referral loop, as the NS response indicates where the resolver should
// try next.
int ret2 = write_record_soa(&outpos, outend, "", offset, CLASS_IN, opt->nsttl, opt->ns, opt->mbox, time(NULL), 604800, 86400, 2592000, 604800);
// printf("wrote SOA record: %i\n", ret2);
if (!ret2) { outbuf[9]++; }
}
// set AA
outbuf[2] |= 4;