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nsec3.cpp
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nsec3.cpp
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/**
* Support for the nsec3 lookup
*
* See also: RFC 5155
*/
#include "nsec3.h"
#include "base32.h"
#include "dns_util.h"
#include "hash_cache.h"
#include "misc.h"
#include "request_context.h"
#include <cassert>
#include <stdio.h>
// #define NSEC3_DEBUG
extern int dnssec_nsec3_bind9_wildcard_compatibility; // from settings
typedef char nsec3_hash_t[DNS_MAX_DOMAIN_LENGTH + 1]; // a fqdn, nsec3 hash name
// ensure we do not add the same nsec3 record (~= hash) twice, since our RRSIG would no longer match
// in that case.
// For this, we keep a list of known nsec3_hashes we've added and return 1 when we've added a
// fqdn hash we haven't seen yet and return 0 if we already added it. The caller should
// not add the nsec3 rr to the output of the package when this method returns 0.
int nsec3_add_already_known_hash(nsec3_hash_t* already_added_nsec3_hashes, int response_info_count, char* hash, int len)
{
nsec3_hash_t hash_to_compare = { 0 };
memcpy(hash_to_compare, hash, len);
for (int i = 0; i < DNS_MAX_NEEDED_NSEC3_RECORDS * response_info_count; ++i) {
char* known_hash = already_added_nsec3_hashes[i];
if (known_hash[0] == '\0') {
memmove(known_hash, hash_to_compare, DNS_MAX_DOMAIN_LENGTH + 1);
return 1;
}
// we do use cmp_label_text here on a FQDN, but we can safely also ignore the length bytes of a FQDN as text.
else if (dns_util::cmp_label_text(known_hash, hash_to_compare, DNS_MAX_DOMAIN_LENGTH) == 0) {
return 0;
}
}
return 0;
}
// Calculates the hash for a given name and salt, iterations.
// Returns the length of the hash. The hash is stored in the [out] output buffer.
int nsec3_calc_hash(request_context_t* context, const char* name, int name_len, const char* salt, int salt_len, uint16 iterations, char* output, int output_len)
{
unsigned char hash[SHA_DIGEST_LENGTH];
int hash_len = iterated_cached_hash(context->dnssec_hash_cache, (unsigned char*)hash, (unsigned char*)salt, salt_len, (unsigned char*)name, name_len, iterations);
return base32_encode((unsigned char*)hash, hash_len, output, output_len);
}
// Hashes a given name with the given NSEC3 parameters.
// Returns the length of the hash. The hash is stored in the [out] output buffer.
int nsec3_hash_name(request_context_t* context, const char* name, int name_len, dns_resource* params, char* output, int output_len)
{
uint16 iterations;
uint8 salt_len = *(params->rdata + 4);
const char* salt = params->rdata + 5;
dns_uint16_decode(params->rdata + 2, &iterations);
char lowercased_name[DNS_MAX_DOMAIN_LENGTH];
if (name_len >= sizeof(lowercased_name) / sizeof(lowercased_name[0]))
return 0; // SERVFAIL via meta data in future releases
for (int i = 0; i < name_len; ++i) {
lowercased_name[i] = LOWERCASE[(unsigned char)name[i]];
}
return nsec3_calc_hash(context, lowercased_name, name_len, salt, salt_len, iterations, output, output_len);
}
// Find the NSEC3PARAM dns_resource for a zone for a given response_info. When there is no NSEC3PARAM
// (either a zone without DNSSEC or an zone with a missing NSEC3PARAM), NULL will be returned.
//
// Also returns the zone apex in the [out]apex and [out]apex_len arguments.
dns_resource* nsec3_find_params(request_context_t* context, response_info_t* response_info, char** apex, int* apex_len)
{
dns_question q1 = response_info->q; // by value, since we modify q1
dns_data_iter_t iter, iter_end;
q1.qtype = DNS_TYPE_NSEC3PARAM;
dns_domain domain;
domain.name = q1.name;
domain.len = q1.len;
dns_resource_type* resourceType = dns_data_get_record_type_data(dns_data_get_label(context, &domain, 0), DNS_TYPE_NSEC3PARAM);
while (domain.len > 0 && *domain.name && resourceType == NULL) {
domain.len -= (*domain.name + 1);
domain.name += *domain.name + 1;
resourceType = dns_data_get_record_type_data(dns_data_get_label(context, &domain, 0), DNS_TYPE_NSEC3PARAM);
}
if (resourceType != NULL) {
dns_resource_v& v = resourceType->records;
int size = v.size();
for (int i = 0; i < size; ++i) {
dns_resource& rr = v[i];
if (NSEC3_HASH_ALGO_SHA1 == *rr.rdata) {
*apex = domain.name;
*apex_len = domain.len;
return &rr;
}
}
}
return NULL;
}
// Gets the dns_resource that matches the given algorithm for a given dns_resource_ve vector.
dns_resource* nsec3_get_rr(dns_resource_v& v, uint8 algo = NSEC3_HASH_ALGO_SHA1)
{
int size = v.size();
for (int i = 0; i < size; ++i) {
dns_resource& nsec3 = v[i];
if (*nsec3.rdata == algo)
return &nsec3;
}
return NULL;
}
int nsec3_find_and_pack_direct_match(request_context_t* context, dns_data_t* dns_data, const char* name, int name_len,
dns_resource* params, const char* apex, int apex_len, struct dns_header* h, char* pkt_out, int buf_len,
int* found_nsec3_when_needed, nsec3_hash_t* already_added_hashes)
{
int len = 0, res;
char question_hash[DNS_MAX_HASH_LENGTH + 1];
char question_hash_fqdn[DNS_MAX_DOMAIN_LENGTH + 1] = { 0 };
int question_hash_len = nsec3_hash_name(context, name, name_len, params, question_hash, sizeof(question_hash));
question_hash_fqdn[0] = question_hash_len;
memcpy(question_hash_fqdn + 1, question_hash, question_hash_len);
memcpy(question_hash_fqdn + 1 + question_hash_len, apex, apex_len);
dns_question q1 = { question_hash_fqdn, DNS_TYPE_NSEC3, DNS_CLASS_IN, (unsigned char)(1 + question_hash_len + apex_len) };
dns_domain domain;
domain.name = q1.name;
domain.len = q1.len;
dns_label* label = dns_data_get_label(context, &domain, 0);
dns_resource_type* resourceType = dns_data_get_record_type_data(label, DNS_TYPE_NSEC3);
// no direct match
dns_resource* nsec3 = NULL;
if (resourceType != NULL)
nsec3 = nsec3_get_rr(resourceType->records);
if (nsec3 != NULL) {
*found_nsec3_when_needed = 1;
if (nsec3_add_already_known_hash(already_added_hashes, context->number_of_response_infos, question_hash_fqdn, DNS_MAX_DOMAIN_LENGTH + 1)) {
res = dns_resource_encode(*nsec3, q1, pkt_out + len, buf_len);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
h->nscount++;
if (len > 0) {
res = dns_data_answer_add_rrsigs(label, pkt_out + len, buf_len, q1, &h->nscount);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
}
}
} else {
*found_nsec3_when_needed = 0;
}
return len;
}
// Finds the next closer for a wildcard hit:
// question: a.z.w.example.com
// wildcard hit: *.w.example.com
// ancestor: w.example.com
// next closer: z.w.example.com
//
// The next closer is the first name that's longer than the ancestor of the wildcard.
//
// returns true when the response_info is a wildcard hit and we found a next closer
//
bool nsec3_find_wildcard_next_closer(response_info_t* response_info, char** next_closer, int* next_closer_len)
{
assert(response_info != NULL);
assert(next_closer != NULL);
assert(next_closer_len != NULL);
dns_question* q = &response_info->q;
// ensure that we can find a next closer
if (!response_info->is_wildcard_hit || response_info->wildcard_name_len < 2 || (response_info->wildcard_name[0] != 2 && response_info->wildcard_name[1] != '*') || q->len < response_info->wildcard_name_len) {
return false;
}
*next_closer = q->name;
*next_closer_len = q->len;
int wildcard_ancestor_len = response_info->wildcard_name_len - 2; // -2 for *.
while (*next_closer_len - (**next_closer + 1) > wildcard_ancestor_len) {
*next_closer_len -= (**next_closer + 1);
*next_closer += (**next_closer + 1);
}
#ifdef NSEC3_DEBUG
char buf[DNS_MAX_DOMAIN_LENGTH];
dns_domain_decode(*next_closer, buf);
printf("next closer: %s\n", buf);
#endif
return true;
}
// Finds and adds the NSEC3 record that covers the given
// name. Returns the length of the data to the packet added.
//
// Beware: A length of 0 does not mean that this case did not apply,
// but could also mean that the NSEC3 record was already
// present in packet. Use found_nsec3_when_needed
// to determine if the NSEC3 record was found.
int nsec3_find_and_add_covering_rr(request_context_t* context,
dns_resource_named_v* nsecs3,
char* name,
int name_len,
dns_resource* params,
dns_header* h,
char* pkt_out,
int buf_len,
int* found_nsec3_when_needed,
nsec3_hash_t* already_added_hashes)
{
int len = 0, res;
// first, create the hash of the name we want to cover
char hash[DNS_MAX_HASH_LENGTH + 2];
int hash_len = nsec3_hash_name(context, name, name_len, params, hash + 1, sizeof(hash));
hash[0] = hash_len;
// Next, search the list of NSEC3 records for our zone in order and
// find the record where the hash of <hash>.zonename is larger
// than the hash of the name we want to cover.
int size = nsecs3->size();
int prev = -1;
for (int i = 0; i < size; ++i) {
dns_resource_named& rr = (*nsecs3)[i];
if (rr.rtype == DNS_TYPE_NSEC3 && *rr.rdata == NSEC3_HASH_ALGO_SHA1) {
// we use cmp_label_text here on a FQDN, because we can safely compare the length bytes
// of the FQDNs
if (dns_util::cmp_label_text(rr.name, hash, SHA_BASE32_DIGEST_LENGTH) > 0) {
break;
}
prev = i;
}
}
if (prev == -1) {
// the first sorted hash > the wanted hash, so our last item covers it:
// search backwards to find the last item that is of NSEC3 type and the correct algorithm
for (int i = size - 1; i >= 0; --i) {
dns_resource_named& rr = (*nsecs3)[i];
if (rr.rtype == DNS_TYPE_NSEC3 && *rr.rdata == NSEC3_HASH_ALGO_SHA1) {
prev = i;
break;
}
}
}
// if we found a covering NSEC3 record, add it to the packet when it's not already there
if (prev != -1) {
*found_nsec3_when_needed = 1;
dns_resource_named& rr = (*nsecs3)[prev];
if (nsec3_add_already_known_hash(already_added_hashes, context->number_of_response_infos, rr.name, rr.name_len)) {
dns_question q1 = { rr.name, rr.rtype, rr.rclass, (unsigned char)rr.name_len };
res = dns_resource_encode(rr, q1, pkt_out + len, buf_len);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
h->nscount++;
if (len > 0) {
dns_domain domain;
domain.name = rr.name;
domain.len = rr.name_len;
dns_label* label = dns_data_get_label(context, &domain, 0);
res = dns_data_answer_add_rrsigs(label, pkt_out + len, buf_len, q1, &h->nscount);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
}
}
}
return len;
}
int nsec3_name_error(request_context_t* context, response_info_t* response_info, char* pkt_out, int buf_len, struct dns_header* h,
int* found_nsec3_when_needed, dns_resource* params, char* apex, int apex_len, nsec3_hash_t* already_added_hashes)
{
int len = 0, res;
dns_data_t* dns_data = context->dns_data;
dns_domain_rrs_t* nsec_data = context->dnssec_nsec_data;
dns_question q = response_info->q;
char domain[DNS_MAX_DOMAIN_LENGTH + 1];
int domain_len = dns_domain_decode(apex, domain);
dns_domain d = { domain, (unsigned char)(domain_len - 2) };
dns_domain_rrs_iter_t iter = nsec_data->find(d);
if (iter == nsec_data->end())
return 0;
// find closest encloser and keep track of the next encloser
bool found_closest_encloser = false;
char* closest_encloser = q.name;
int closest_encloser_len = q.len;
char* next_closer = q.name;
int next_closer_len = q.len;
while (closest_encloser_len > 0 && *closest_encloser && !found_closest_encloser) {
closest_encloser_len -= (*closest_encloser + 1);
closest_encloser += *closest_encloser + 1;
dns_domain domainObj;
domainObj.name = closest_encloser;
domainObj.len = closest_encloser_len;
if (dns_data_get_label(context, &domainObj, 0) != NULL) {
found_closest_encloser = true;
} else {
next_closer_len -= (*next_closer + 1);
next_closer += (*next_closer + 1);
}
}
if (found_closest_encloser) {
// nsec3 that matches the closest encloser
res = nsec3_find_and_pack_direct_match(context, dns_data, closest_encloser, closest_encloser_len, params,
apex, apex_len, h, pkt_out + len, buf_len,
found_nsec3_when_needed, already_added_hashes);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
if (!*found_nsec3_when_needed) {
h->nscount -= 0;
return 0;
}
// nsec3 that covers the next closer
res = nsec3_find_and_add_covering_rr(context, &iter->second, next_closer, next_closer_len, params,
h, pkt_out + len, buf_len,
found_nsec3_when_needed, already_added_hashes);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
if (!*found_nsec3_when_needed) {
h->nscount -= 1;
return 0;
}
char wildcard[DNS_MAX_DOMAIN_LENGTH + 1] = "\1*";
memcpy(wildcard + 2, closest_encloser, closest_encloser_len);
int wildcard_len = closest_encloser_len + 2;
// nsec3 that matches the wildcard rr at the closest encloser
res = nsec3_find_and_add_covering_rr(context, &iter->second, wildcard, wildcard_len, params,
h, pkt_out + len, buf_len,
found_nsec3_when_needed, already_added_hashes);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
if (!*found_nsec3_when_needed) {
h->nscount -= 2;
return 0;
}
}
return len;
}
int nsec3_wildcard_hit(request_context_t* context, response_info_t* response_info, char* pkt_out, int buf_len, struct dns_header* h,
int* found_nsec3_when_needed, dns_resource* params, char* apex, int apex_len, nsec3_hash_t* already_added_hashes)
{
int len = 0, res;
dns_data_t* dns_data = context->dns_data;
dns_domain_rrs_t* nsec_data = context->dnssec_nsec_data;
// find next closer name:
// 0. (e.g. qname = a.z.w.example.)
// 1. find the wildcard name that matches (*.w.example)
// 2. take the ancestor of the wildcard (w.example)
// 3. take the next closer name (z.w.example)
// 4. prove that it doesn't exist by providing an nsec
// that covers the hash of the next closer name
// .e.g. nsec.owner_name < hash(z.w.example) < nsec.next_owner_name
char* next_closer;
int next_closer_len;
bool wildcard_found = nsec3_find_wildcard_next_closer(response_info, &next_closer, &next_closer_len);
if (wildcard_found) {
char domain[DNS_MAX_DOMAIN_LENGTH + 1];
int domain_len = dns_domain_decode(apex, domain);
dns_domain d = { domain, (unsigned char)(domain_len - 2) };
dns_domain_rrs_iter_t iter = nsec_data->find(d);
if (iter != nsec_data->end()) {
res = nsec3_find_and_add_covering_rr(context, &iter->second, next_closer,
next_closer_len, params, h, pkt_out + len, buf_len,
found_nsec3_when_needed, already_added_hashes);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
}
}
// bug for bug compatible with bind9 if enabled
// bind9 returns the closest provable encloser on a direct wildcard hit.
// This isn't strictly necessary at all, because the existance of the closest encloser
// is proven by the presence of the expanded wildcard in the answer section.
if (dnssec_nsec3_bind9_wildcard_compatibility) {
#ifdef NSEC3_DEBUG
printf("NSEC3: wildcard hit, adding extra NSEC3 for bind compatiblity\n");
#endif //NSEC3_DEBUG
// nsec3 that matches the closest encloser
char* closest_encloser = next_closer + *next_closer + 1;
int closest_encloser_len = next_closer_len - (*next_closer + 1);
// nsec3 that matches the closest encloser
res = nsec3_find_and_pack_direct_match(context, dns_data, closest_encloser, closest_encloser_len, params,
apex, apex_len, h, pkt_out + len, buf_len,
found_nsec3_when_needed, already_added_hashes);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
}
return len;
}
int nsec3_check_wildcard_nodata_hit(request_context_t* context, response_info_t* response_info, char* pkt_out, int buf_len, struct dns_header* h,
int* found_nsec3_when_needed, dns_resource* params, char* apex, int apex_len, nsec3_hash_t* already_added_hashes)
{
int len = 0, res;
dns_data_t* dns_data = context->dns_data;
dns_domain_rrs_t* nsec_data = context->dnssec_nsec_data;
// 2) check for a wildcard hit
char* next_closer;
int next_closer_len;
bool wildcard_found = nsec3_find_wildcard_next_closer(response_info, &next_closer, &next_closer_len);
if (wildcard_found) {
char domain[DNS_MAX_DOMAIN_LENGTH + 1];
int domain_len = dns_domain_decode(apex, domain);
dns_domain d = { domain, (unsigned char)(domain_len - 2) };
dns_domain_rrs_iter_t iter = nsec_data->find(d);
if (iter == nsec_data->end())
return 0;
// nsec3 that matches the closest encloser
char* closest_encloser = next_closer + *next_closer + 1;
int closest_encloser_len = next_closer_len - (*next_closer + 1);
// nsec3 that matches the closest encloser
res = nsec3_find_and_pack_direct_match(context, dns_data, closest_encloser, closest_encloser_len, params,
apex, apex_len, h, pkt_out + len, buf_len,
found_nsec3_when_needed, already_added_hashes);
if (res < 0) {
return 1;
}
len += res;
buf_len -= res;
if (!*found_nsec3_when_needed) {
h->nscount -= 0;
return 0;
}
// nsec3 that covers the next closer
res = nsec3_find_and_add_covering_rr(context, &iter->second, next_closer, next_closer_len, params,
h, pkt_out + len, buf_len,
found_nsec3_when_needed, already_added_hashes);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
if (!*found_nsec3_when_needed) {
h->nscount -= 1;
return 0;
}
char wildcard[DNS_MAX_DOMAIN_LENGTH + 1] = "\1*";
memcpy(wildcard + 2, closest_encloser, closest_encloser_len);
int wildcard_len = closest_encloser_len + 2;
// nsec3 that matches the wildcard rr at the closest encloser
res = nsec3_find_and_pack_direct_match(context, dns_data, wildcard, wildcard_len, params,
apex, apex_len, h, pkt_out + len, buf_len,
found_nsec3_when_needed, already_added_hashes);
if (res < 0) {
return -1;
}
len += res;
buf_len -= res;
if (!*found_nsec3_when_needed) {
h->nscount -= 2;
return 0;
}
}
return len;
}
int nsec3_name_error_or_no_data(request_context_t* context, response_info_t* response_info, char* pkt_out, int buf_len, struct dns_header* h,
int* found_nsec3_when_needed, dns_resource* params, char* apex, int apex_len, nsec3_hash_t* already_added_hashes, int* is_empty_non_terminal_nsec3)
{
// name error or no data, 3 possibilities:
// 1) empty non-terminal hit -> search for a hit on hash name
// 2) wildcard hit without data -> search for a matching wildcard (must be after 1,
// consider existing rr a.y.w.example and *.w.example -> the wildcard would
// hit before the empty non terminal y.w.example otherwise)
// 3) name does not exist
int len = 0;
dns_data_t* dns_data = context->dns_data;
dns_question q = response_info->q;
// 1) empty non-terminal
int did_find_direct_match_nsec3 = 0;
int added_len = nsec3_find_and_pack_direct_match(context, dns_data, q.name, q.len, params,
apex, apex_len, h, pkt_out + len, buf_len,
&did_find_direct_match_nsec3, already_added_hashes);
if (added_len < 0) {
return -1;
}
if (did_find_direct_match_nsec3) {
if (found_nsec3_when_needed != NULL)
*found_nsec3_when_needed = 1;
#ifdef NSEC3_DEBUG
printf("NSEC3: empty non-terminal: no data\n");
#endif //NSEC3_DEBUG
len += added_len;
buf_len -= added_len;
// matching empty non-terminal
// RFC5155, 7.2.3. No Data Responses, QTYPE is not DS
// RFC5155, 7.2.4. No Data Responses, QTYPE is DS -> this is okay, this NSEC3 proves the non-existance of the DS record
if (is_empty_non_terminal_nsec3 != NULL)
*is_empty_non_terminal_nsec3 = 1;
} else {
// XXX: RFC5155, 7.2.4. No Data Responses, QTYPE is DS ????
// 2) wildcard hit without data
// RFC5155, 7.2.3. No Data Responses, QTYPE is not DS
int did_matched_wildcard_nodata_nsec3 = 0;
int added_len = nsec3_check_wildcard_nodata_hit(context, response_info, pkt_out + len, buf_len, h, &did_matched_wildcard_nodata_nsec3, params, apex, apex_len, already_added_hashes);
if (added_len < 0) {
return -1;
}
if (did_matched_wildcard_nodata_nsec3) {
if (found_nsec3_when_needed != NULL)
*found_nsec3_when_needed = 1;
#ifdef NSEC3_DEBUG
printf("NSEC3: wildcard hit: no data\n");
#endif //NSEC3_DEBUG
len = added_len;
} else {
#ifdef NSEC3_DEBUG
printf("NSEC3: name error\n");
#endif //NSEC3_DEBUG
// 3) name does not exist (NAMEERROR)
// RFC5155, 7.2.2. Name Error Responses
len = nsec3_name_error(context, response_info, pkt_out + len, buf_len, h, found_nsec3_when_needed, params, apex, apex_len, already_added_hashes);
}
}
return len;
}
int dnssec_add_nsec3s_for_response_info(request_context_t* context, response_info_t* response_info, char* pkt_out, int buf_len, struct dns_header* h,
int* found_nsec3_when_needed, int* is_empty_non_terminal_nsec3, nsec3_hash_t* already_added_hashes)
{
int len = 0;
dns_data_t* dns_data = context->dns_data;
char* apex = 0;
int apex_len = 0;
dns_resource* params = nsec3_find_params(context, response_info, &apex, &apex_len);
if (NULL == params) {
#ifdef NSEC3_DEBUG
printf("NSEC3: no NSEC3PARAMS found\n");
#endif
return 0;
}
if (is_empty_non_terminal_nsec3 != NULL) {
*is_empty_non_terminal_nsec3 = 0;
}
// HANDLING
if (response_info->is_delegation) {
// RFC5155, 7.2.7. Referrals to Unsigned Subzones
if (!response_info->is_secure_delegation) {
#ifdef NSEC3_DEBUG
printf("NSEC3: insecure delegation: needs nsec3 for the direct hit\n");
#endif //NSEC3_DEBUG
// if this is a query for NS records on an insecure subzone delegation,
// we should return the matching NSEC3 per RFC5155 (7.2.7) to prove there
// are no DS records (the NSEC3 proves this with its types field) under
// this label.
len = nsec3_find_and_pack_direct_match(context, dns_data, response_info->delegation_name, response_info->delegation_name_len, params, apex, apex_len, h, pkt_out + len, buf_len, found_nsec3_when_needed, already_added_hashes);
} else {
#ifdef NSEC3_DEBUG
printf("NSEC3: secure delegation: DS records present with RRSIGS\n");
#endif //NSEC3_DEBUG
// thisis a secure subzone delegation, since there are DS records. We do not need to return
// any NSEC3s, since the existance of the DS records will prove the secure-ness of the delegation.
// the NS-response should include these DS records, which will be signed, making it possible
// to validate our response.
if (found_nsec3_when_needed != NULL)
*found_nsec3_when_needed = true;
}
} else if (response_info->is_name_error || response_info->is_no_data) {
#ifdef NSEC3_DEBUG
printf("NSEC3: name error OR no data\n");
#endif //NSEC3_DEBUG
// RFC5155, 7.2.2. Name Error Responses or 7.2.3. No Data Responses, QTYPE is not DS or 7.2.4. No Data Responses, QTYPE is DS
*found_nsec3_when_needed = 0;
len = nsec3_name_error_or_no_data(context, response_info, pkt_out + len, buf_len, h, found_nsec3_when_needed, params, apex, apex_len, already_added_hashes, is_empty_non_terminal_nsec3);
} else if (response_info->is_wildcard_hit) {
#ifdef NSEC3_DEBUG
printf("NSEC3: wildcard hit\n");
#endif //NSEC3_DEBUG
// RFC5155, 7.2.6. Wildcard Answer Responses
len = nsec3_wildcard_hit(context, response_info, pkt_out + len, buf_len, h, found_nsec3_when_needed, params, apex, apex_len, already_added_hashes);
} else {
*found_nsec3_when_needed = true;
#ifdef NSEC3_DEBUG
printf("NSEC3: direct hit, RRSIGS present or not signed\n");
#endif //NSEC3_DEBUG
}
return len;
}
int dnssec_add_nsec3s(request_context_t* context, char* pkt_out, int buf_len, struct dns_header* h, int* found_nsec3_when_needed, int* is_empty_non_terminal_nsec3)
{
int len = 0, res;
nsec3_hash_t* already_added_hashes = (nsec3_hash_t*)malloc(sizeof(nsec3_hash_t) * DNS_MAX_NEEDED_NSEC3_RECORDS * (context->number_of_response_infos)); // already known hashes
for (int i = 0; i < DNS_MAX_NEEDED_NSEC3_RECORDS * (context->number_of_response_infos); i++) {
already_added_hashes[i][0] = '\0';
}
if (context->number_of_response_infos > 1) {
is_empty_non_terminal_nsec3 = NULL; // there's no point in checking for non empty terminals when we are following a CNAME chain
}
#ifdef NSEC3_DEBUG
printf("NSEC3: looking for NSEC3 records (num chains: %d)\n", context->number_of_response_infos);
#endif //NSEC3_DEBUG
// loop over each response info, so we do an NSEC3 lookup for each part of a CNAME chain also
// we say we found all nsec3 records when needed, when each part of the chain has its nsec3 records found.
int added_all_nsec3s = 1;
for (int i = 0; i < context->number_of_response_infos; ++i) {
response_info_t* response_info = &context->response_info_chain[i];
#ifdef NSEC3_DEBUG
printf("%d from %d:\n", i + 1, context->number_of_response_infos);
response_info->debug_print();
#endif //NSEC3_DEBUG
int added_nsec3s = 0;
res = dnssec_add_nsec3s_for_response_info(context, response_info, pkt_out + len, buf_len, h, &added_nsec3s, is_empty_non_terminal_nsec3, already_added_hashes);
if (res < 0) {
free(already_added_hashes);
return -1;
}
len += res;
buf_len -= res;
added_all_nsec3s &= added_nsec3s;
#ifdef NSEC3_DEBUG
printf("==================\n\n");
#endif //NSEC3_DEBUG
}
if (found_nsec3_when_needed != NULL) {
*found_nsec3_when_needed = added_all_nsec3s;
}
free(already_added_hashes);
return len;
}