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src/sbin/unwind/libunbound/dns64/dns64.c

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/*
* dns64/dns64.c - DNS64 module
*
* Copyright (c) 2009, Viagénie. All rights reserved.
*
* This software is open source.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of Viagénie nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* \file
*
* This file contains a module that performs DNS64 query processing.
*/
#include "config.h"
#include "dns64/dns64.h"
#include "services/cache/dns.h"
#include "services/cache/rrset.h"
#include "util/config_file.h"
#include "util/data/msgreply.h"
#include "util/fptr_wlist.h"
#include "util/net_help.h"
#include "util/regional.h"
#include "util/storage/dnstree.h"
#include "util/data/dname.h"
#include "sldns/str2wire.h"
/******************************************************************************
* *
* STATIC CONSTANTS *
* *
******************************************************************************/
/**
* This is the default DNS64 prefix that is used when the dns64 module is listed
* in module-config but when the dns64-prefix variable is not present.
*/
static const char DEFAULT_DNS64_PREFIX[] = "64:ff9b::/96";
/**
* Maximum length of a domain name in a PTR query in the .in-addr.arpa tree.
*/
#define MAX_PTR_QNAME_IPV4 30
/**
* State of DNS64 processing for a query.
*/
enum dns64_state {
DNS64_INTERNAL_QUERY, /**< Internally-generated query, no DNS64
processing. */
DNS64_NEW_QUERY, /**< Query for which we're the first module in
line. */
DNS64_SUBQUERY_FINISHED /**< Query for which we generated a sub-query, and
for which this sub-query is finished. */
};
/**
* Per-query module-specific state. For the DNS64 module.
*/
struct dns64_qstate {
/** State of the DNS64 module. */
enum dns64_state state;
/** If the dns64 module started with no_cache bool set in the qstate,
* a message to tell it to not modify the cache contents, then this
* is true. The dns64 module is then free to modify that flag for
* its own purposes.
* Otherwise, it is false, the dns64 module was not told to no_cache */
int started_no_cache_store;
};
/******************************************************************************
* *
* STRUCTURES *
* *
******************************************************************************/
/**
* This structure contains module configuration information. One instance of
* this structure exists per instance of the module. Normally there is only one
* instance of the module.
*/
struct dns64_env {
/**
* DNS64 prefix address. We're using a full sockaddr instead of just an
* in6_addr because we can reuse Unbound's generic string parsing functions.
* It will always contain a sockaddr_in6, and only the sin6_addr member will
* ever be used.
*/
struct sockaddr_storage prefix_addr;
/**
* This is always sizeof(sockaddr_in6).
*/
socklen_t prefix_addrlen;
/**
* This is the CIDR length of the prefix. It needs to be between 0 and 96.
*/
int prefix_net;
/**
* Tree of names for which AAAA is ignored. always synthesize from A.
*/
rbtree_type ignore_aaaa;
};
/******************************************************************************
* *
* UTILITY FUNCTIONS *
* *
******************************************************************************/
/**
* Generic macro for swapping two variables.
*
* \param t Type of the variables. (e.g. int)
* \param a First variable.
* \param b Second variable.
*
* \warning Do not attempt something foolish such as swap(int,a++,b++)!
*/
#define swap(t,a,b) do {t x = a; a = b; b = x;} while(0)
/**
* Reverses a string.
*
* \param begin Points to the first character of the string.
* \param end Points one past the last character of the string.
*/
static void
reverse(char* begin, char* end)
{
while ( begin < --end ) {
swap(char, *begin, *end);
++begin;
}
}
/**
* Convert an unsigned integer to a string. The point of this function is that
* of being faster than sprintf().
*
* \param n The number to be converted.
* \param s The result will be written here. Must be large enough, be careful!
*
* \return The number of characters written.
*/
static int
uitoa(unsigned n, char* s)
{
char* ss = s;
do {
*ss++ = '0' + n % 10;
} while (n /= 10);
reverse(s, ss);
return ss - s;
}
/**
* Extract an IPv4 address embedded in the IPv6 address \a ipv6 at offset \a
* offset (in bits). Note that bits are not necessarily aligned on bytes so we
* need to be careful.
*
* \param ipv6 IPv6 address represented as a 128-bit array in big-endian
* order.
* \param ipv6_len length of the ipv6 byte array.
* \param offset Index of the MSB of the IPv4 address embedded in the IPv6
* address.
*/
static uint32_t
extract_ipv4(const uint8_t ipv6[], size_t ipv6_len, const int offset)
{
uint32_t ipv4 = 0;
int i, pos;
log_assert(ipv6_len == 16); (void)ipv6_len;
log_assert(offset == 32 || offset == 40 || offset == 48 || offset == 56 ||
offset == 64 || offset == 96);
for(i = 0, pos = offset / 8; i < 4; i++, pos++) {
if (pos == 8)
pos++;
ipv4 = ipv4 << 8;
ipv4 |= ipv6[pos];
}
return ipv4;
}
/**
* Builds the PTR query name corresponding to an IPv4 address. For example,
* given the number 3,464,175,361, this will build the string
* "\03206\03123\0231\011\07in-addr\04arpa".
*
* \param ipv4 IPv4 address represented as an unsigned 32-bit number.
* \param ptr The result will be written here. Must be large enough, be
* careful!
* \param nm_len length of the ptr buffer.
*
* \return The number of characters written.
*/
static size_t
ipv4_to_ptr(uint32_t ipv4, char ptr[], size_t nm_len)
{
static const char IPV4_PTR_SUFFIX[] = "\07in-addr\04arpa";
int i;
char* c = ptr;
log_assert(nm_len == MAX_PTR_QNAME_IPV4); (void)nm_len;
for (i = 0; i < 4; ++i) {
*c = uitoa((unsigned int)(ipv4 % 256), c + 1);
c += *c + 1;
log_assert(c < ptr+nm_len);
ipv4 /= 256;
}
log_assert(c + sizeof(IPV4_PTR_SUFFIX) <= ptr+nm_len);
memmove(c, IPV4_PTR_SUFFIX, sizeof(IPV4_PTR_SUFFIX));
return c + sizeof(IPV4_PTR_SUFFIX) - ptr;
}
/**
* Converts an IPv6-related domain name string from a PTR query into an IPv6
* address represented as a 128-bit array.
*
* \param ptr The domain name. (e.g. "\011[...]\010\012\016\012\03ip6\04arpa")
* \param ipv6 The result will be written here, in network byte order.
* \param ipv6_len length of the ipv6 byte array.
*
* \return 1 on success, 0 on failure.
*/
static int
ptr_to_ipv6(const char* ptr, uint8_t ipv6[], size_t ipv6_len)
{
int i;
log_assert(ipv6_len == 16); (void)ipv6_len;
for (i = 0; i < 64; i++) {
int x;
if (ptr[i++] != 1)
return 0;
if (ptr[i] >= '0' && ptr[i] <= '9') {
x = ptr[i] - '0';
} else if (ptr[i] >= 'a' && ptr[i] <= 'f') {
x = ptr[i] - 'a' + 10;
} else if (ptr[i] >= 'A' && ptr[i] <= 'F') {
x = ptr[i] - 'A' + 10;
} else {
return 0;
}
ipv6[15-i/4] |= x << (2 * ((i-1) % 4));
}
return 1;
}
/**
* Synthesize an IPv6 address based on an IPv4 address and the DNS64 prefix.
*
* \param prefix_addr DNS64 prefix address.
* \param prefix_addr_len length of the prefix_addr buffer.
* \param prefix_net CIDR length of the DNS64 prefix. Must be between 0 and 96.
* \param a IPv4 address.
* \param a_len length of the a buffer.
* \param aaaa IPv6 address. The result will be written here.
* \param aaaa_len length of the aaaa buffer.
*/
static void
synthesize_aaaa(const uint8_t prefix_addr[], size_t prefix_addr_len,
int prefix_net, const uint8_t a[], size_t a_len, uint8_t aaaa[],
size_t aaaa_len)
{
size_t i;
int pos;
log_assert(prefix_addr_len == 16 && a_len == 4 && aaaa_len == 16);
log_assert(prefix_net == 32 || prefix_net == 40 || prefix_net == 48 ||
prefix_net == 56 || prefix_net == 64 || prefix_net == 96);
(void)prefix_addr_len; (void)a_len; (void)aaaa_len;
memcpy(aaaa, prefix_addr, 16);
for(i = 0, pos = prefix_net / 8; i < a_len; i++, pos++) {
if(pos == 8)
aaaa[pos++] = 0;
aaaa[pos] = a[i];
}
}
/******************************************************************************
* *
* DNS64 MODULE FUNCTIONS *
* *
******************************************************************************/
/**
* insert ignore_aaaa element into the tree
* @param dns64_env: module env.
* @param str: string with domain name.
* @return false on failure.
*/
static int
dns64_insert_ignore_aaaa(struct dns64_env* dns64_env, char* str)
{
/* parse and insert element */
struct name_tree_node* node;
node = (struct name_tree_node*)calloc(1, sizeof(*node));
if(!node) {
log_err("out of memory");
return 0;
}
node->name = sldns_str2wire_dname(str, &node->len);
if(!node->name) {
free(node);
log_err("cannot parse dns64-ignore-aaaa: %s", str);
return 0;
}
node->labs = dname_count_labels(node->name);
node->dclass = LDNS_RR_CLASS_IN;
if(!name_tree_insert(&dns64_env->ignore_aaaa, node,
node->name, node->len, node->labs, node->dclass)) {
/* ignore duplicate element */
free(node->name);
free(node);
return 1;
}
return 1;
}
/**
* This function applies the configuration found in the parsed configuration
* file \a cfg to this instance of the dns64 module. Currently only the DNS64
* prefix (a.k.a. Pref64) is configurable.
*
* \param dns64_env Module-specific global parameters.
* \param cfg Parsed configuration file.
*/
static int
dns64_apply_cfg(struct dns64_env* dns64_env, struct config_file* cfg)
{
struct config_strlist* s;
verbose(VERB_ALGO, "dns64-prefix: %s", cfg->dns64_prefix);
if (!netblockstrtoaddr(cfg->dns64_prefix ? cfg->dns64_prefix :
DEFAULT_DNS64_PREFIX, 0, &dns64_env->prefix_addr,
&dns64_env->prefix_addrlen, &dns64_env->prefix_net)) {
log_err("cannot parse dns64-prefix netblock: %s", cfg->dns64_prefix);
return 0;
}
if (!addr_is_ip6(&dns64_env->prefix_addr, dns64_env->prefix_addrlen)) {
log_err("dns64_prefix is not IPv6: %s", cfg->dns64_prefix);
return 0;
}
if (dns64_env->prefix_net != 32 && dns64_env->prefix_net != 40 &&
dns64_env->prefix_net != 48 && dns64_env->prefix_net != 56 &&
dns64_env->prefix_net != 64 && dns64_env->prefix_net != 96 ) {
log_err("dns64-prefix length it not 32, 40, 48, 56, 64 or 96: %s",
cfg->dns64_prefix);
return 0;
}
for(s = cfg->dns64_ignore_aaaa; s; s = s->next) {
if(!dns64_insert_ignore_aaaa(dns64_env, s->str))
return 0;
}
name_tree_init_parents(&dns64_env->ignore_aaaa);
return 1;
}
/**
* Initializes this instance of the dns64 module.
*
* \param env Global state of all module instances.
* \param id This instance's ID number.
*/
int
dns64_init(struct module_env* env, int id)
{
struct dns64_env* dns64_env =
(struct dns64_env*)calloc(1, sizeof(struct dns64_env));
if (!dns64_env) {
log_err("malloc failure");
return 0;
}
env->modinfo[id] = (void*)dns64_env;
name_tree_init(&dns64_env->ignore_aaaa);
if (!dns64_apply_cfg(dns64_env, env->cfg)) {
log_err("dns64: could not apply configuration settings.");
return 0;
}
return 1;
}
/** free ignore AAAA elements */
static void
free_ignore_aaaa_node(rbnode_type* node, void* ATTR_UNUSED(arg))
{
struct name_tree_node* n = (struct name_tree_node*)node;
if(!n) return;
free(n->name);
free(n);
}
/**
* Deinitializes this instance of the dns64 module.
*
* \param env Global state of all module instances.
* \param id This instance's ID number.
*/
void
dns64_deinit(struct module_env* env, int id)
{
struct dns64_env* dns64_env;
if (!env)
return;
dns64_env = (struct dns64_env*)env->modinfo[id];
if(dns64_env) {
traverse_postorder(&dns64_env->ignore_aaaa, free_ignore_aaaa_node,
NULL);
}
free(env->modinfo[id]);
env->modinfo[id] = NULL;
}
/**
* Handle PTR queries for IPv6 addresses. If the address belongs to the DNS64
* prefix, we must do a PTR query for the corresponding IPv4 address instead.
*
* \param qstate Query state structure.
* \param id This module instance's ID number.
*
* \return The new state of the query.
*/
static enum module_ext_state
handle_ipv6_ptr(struct module_qstate* qstate, int id)
{
struct dns64_env* dns64_env = (struct dns64_env*)qstate->env->modinfo[id];
struct module_qstate* subq = NULL;
struct query_info qinfo;
struct sockaddr_in6 sin6;
/* Convert the PTR query string to an IPv6 address. */
memset(&sin6, 0, sizeof(sin6));
sin6.sin6_family = AF_INET6;
if (!ptr_to_ipv6((char*)qstate->qinfo.qname, sin6.sin6_addr.s6_addr,
sizeof(sin6.sin6_addr.s6_addr)))
return module_wait_module; /* Let other module handle this. */
/*
* If this IPv6 address is not part of our DNS64 prefix, then we don't need
* to do anything. Let another module handle the query.
*/
if (addr_in_common((struct sockaddr_storage*)&sin6, 128,
&dns64_env->prefix_addr, dns64_env->prefix_net,
(socklen_t)sizeof(sin6)) != dns64_env->prefix_net)
return module_wait_module;
verbose(VERB_ALGO, "dns64: rewrite PTR record");
/*
* Create a new PTR query info for the domain name corresponding to the IPv4
* address corresponding to the IPv6 address corresponding to the original
* PTR query domain name.
*/
qinfo = qstate->qinfo;
if (!(qinfo.qname = regional_alloc(qstate->region, MAX_PTR_QNAME_IPV4)))
return module_error;
qinfo.qname_len = ipv4_to_ptr(extract_ipv4(sin6.sin6_addr.s6_addr,
sizeof(sin6.sin6_addr.s6_addr), dns64_env->prefix_net),
(char*)qinfo.qname, MAX_PTR_QNAME_IPV4);
/* Create the new sub-query. */
fptr_ok(fptr_whitelist_modenv_attach_sub(qstate->env->attach_sub));
if(!(*qstate->env->attach_sub)(qstate, &qinfo, qstate->query_flags, 0, 0,
&subq))
return module_error;
if (subq) {
subq->curmod = id;
subq->ext_state[id] = module_state_initial;
subq->minfo[id] = NULL;
}
return module_wait_subquery;
}
static enum module_ext_state
generate_type_A_query(struct module_qstate* qstate, int id)
{
struct module_qstate* subq = NULL;
struct query_info qinfo;
verbose(VERB_ALGO, "dns64: query A record");
/* Create a new query info. */
qinfo = qstate->qinfo;
qinfo.qtype = LDNS_RR_TYPE_A;
/* Start the sub-query. */
fptr_ok(fptr_whitelist_modenv_attach_sub(qstate->env->attach_sub));
if(!(*qstate->env->attach_sub)(qstate, &qinfo, qstate->query_flags, 0,
0, &subq))
{
verbose(VERB_ALGO, "dns64: sub-query creation failed");
return module_error;
}
if (subq) {
subq->curmod = id;
subq->ext_state[id] = module_state_initial;
subq->minfo[id] = NULL;
}
return module_wait_subquery;
}
/**
* See if query name is in the always synth config.
* The ignore-aaaa list has names for which the AAAA for the domain is
* ignored and the A is always used to create the answer.
* @param qstate: query state.
* @param id: module id.
* @return true if the name is covered by ignore-aaaa.
*/
static int
dns64_always_synth_for_qname(struct module_qstate* qstate, int id)
{
struct dns64_env* dns64_env = (struct dns64_env*)qstate->env->modinfo[id];
int labs = dname_count_labels(qstate->qinfo.qname);
struct name_tree_node* node = name_tree_lookup(&dns64_env->ignore_aaaa,
qstate->qinfo.qname, qstate->qinfo.qname_len, labs,
qstate->qinfo.qclass);
return (node != NULL);
}
/**
* Handles the "pass" event for a query. This event is received when a new query
* is received by this module. The query may have been generated internally by
* another module, in which case we don't want to do any special processing
* (this is an interesting discussion topic), or it may be brand new, e.g.
* received over a socket, in which case we do want to apply DNS64 processing.
*
* \param qstate A structure representing the state of the query that has just
* received the "pass" event.
* \param id This module's instance ID.
*
* \return The new state of the query.
*/
static enum module_ext_state
handle_event_pass(struct module_qstate* qstate, int id)
{
struct dns64_qstate* iq = (struct dns64_qstate*)qstate->minfo[id];
int synth_all_cfg = qstate->env->cfg->dns64_synthall;
int synth_qname = 0;
if(iq && iq->state == DNS64_NEW_QUERY
&& qstate->qinfo.qtype == LDNS_RR_TYPE_PTR
&& qstate->qinfo.qname_len == 74
&& !strcmp((char*)&qstate->qinfo.qname[64], "\03ip6\04arpa")) {
/* Handle PTR queries for IPv6 addresses. */
return handle_ipv6_ptr(qstate, id);
}
if(iq && iq->state == DNS64_NEW_QUERY &&
qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA &&
(synth_all_cfg ||
(synth_qname=(dns64_always_synth_for_qname(qstate, id)
&& !(qstate->query_flags & BIT_CD))))) {
if(synth_qname)
verbose(VERB_ALGO, "dns64: ignore-aaaa and synthesize anyway");
return generate_type_A_query(qstate, id);
}
/* We are finished when our sub-query is finished. */
if(iq && iq->state == DNS64_SUBQUERY_FINISHED)
return module_finished;
/* Otherwise, pass request to next module. */
verbose(VERB_ALGO, "dns64: pass to next module");
return module_wait_module;
}
/**
* Handles the "done" event for a query. We need to analyze the response and
* maybe issue a new sub-query for the A record.
*
* \param qstate A structure representing the state of the query that has just
* received the "pass" event.
* \param id This module's instance ID.
*
* \return The new state of the query.
*/
static enum module_ext_state
handle_event_moddone(struct module_qstate* qstate, int id)
{
struct dns64_qstate* iq = (struct dns64_qstate*)qstate->minfo[id];
/*
* In many cases we have nothing special to do. From most to least common:
*
* - An internal query.
* - A query for a record type other than AAAA.
* - CD FLAG was set on querier
* - An AAAA query for which an error was returned.(qstate.return_rcode)
* -> treated as servfail thus synthesize (sec 5.1.3 6147), thus
* synthesize in (sec 5.1.2 of RFC6147).
* - A successful AAAA query with an answer.
*/
/* When an AAAA query completes check if we want to perform DNS64
* synthesis. We skip queries with DNSSEC enabled (!CD) and
* ones generated by us to retrive the A/PTR record to use for
* synth. */
int could_synth =
qstate->qinfo.qtype == LDNS_RR_TYPE_AAAA &&
(!iq || iq->state != DNS64_INTERNAL_QUERY) &&
!(qstate->query_flags & BIT_CD);
int has_data = /* whether query returned non-empty rrset */
qstate->return_msg &&
qstate->return_msg->rep &&
reply_find_answer_rrset(&qstate->qinfo, qstate->return_msg->rep);
int synth_qname = 0;
if(could_synth &&
(!has_data ||
(synth_qname=dns64_always_synth_for_qname(qstate, id)))) {
if(synth_qname)
verbose(VERB_ALGO, "dns64: ignore-aaaa and synthesize anyway");
return generate_type_A_query(qstate, id);
}
/* Store the response in cache. */
if( (!iq || !iq->started_no_cache_store) &&
qstate->return_msg &&
qstate->return_msg->rep &&
!dns_cache_store(
qstate->env, &qstate->qinfo, qstate->return_msg->rep,
0, 0, 0, NULL,
qstate->query_flags, qstate->qstarttime))
log_err("out of memory");
/* do nothing */
return module_finished;
}
/**
* This is the module's main() function. It gets called each time a query
* receives an event which we may need to handle. We respond by updating the
* state of the query.
*
* \param qstate Structure containing the state of the query.
* \param event Event that has just been received.
* \param id This module's instance ID.
* \param outbound State of a DNS query on an authoritative server. We never do
* our own queries ourselves (other modules do it for us), so
* this is unused.
*/
void
dns64_operate(struct module_qstate* qstate, enum module_ev event, int id,
struct outbound_entry* outbound)
{
struct dns64_qstate* iq;
(void)outbound;
verbose(VERB_QUERY, "dns64[module %d] operate: extstate:%s event:%s",
id, strextstate(qstate->ext_state[id]),
strmodulevent(event));
log_query_info(VERB_QUERY, "dns64 operate: query", &qstate->qinfo);
switch(event) {
case module_event_new:
/* Tag this query as being new and fall through. */
if (!(iq = (struct dns64_qstate*)regional_alloc(
qstate->region, sizeof(*iq)))) {
log_err("out of memory");
qstate->ext_state[id] = module_error;
return;
}
qstate->minfo[id] = iq;
iq->state = DNS64_NEW_QUERY;
iq->started_no_cache_store = qstate->no_cache_store;
qstate->no_cache_store = 1;
/* fallthrough */
case module_event_pass:
qstate->ext_state[id] = handle_event_pass(qstate, id);
break;
case module_event_moddone:
qstate->ext_state[id] = handle_event_moddone(qstate, id);
break;
default:
qstate->ext_state[id] = module_finished;
break;
}
if(qstate->ext_state[id] == module_finished) {
iq = (struct dns64_qstate*)qstate->minfo[id];
if(iq && iq->state != DNS64_INTERNAL_QUERY)
qstate->no_cache_store = iq->started_no_cache_store;
}
}
static void
dns64_synth_aaaa_data(const struct ub_packed_rrset_key* fk,
const struct packed_rrset_data* fd,
struct ub_packed_rrset_key *dk,
struct packed_rrset_data **dd_out, struct regional *region,
struct dns64_env* dns64_env )
{
struct packed_rrset_data *dd;
size_t i;
/*
* Create synthesized AAAA RR set data. We need to allocated extra memory
* for the RRs themselves. Each RR has a length, TTL, pointer to wireformat
* data, 2 bytes of data length, and 16 bytes of IPv6 address.
*/
if(fd->count > RR_COUNT_MAX) {
*dd_out = NULL;
return; /* integer overflow protection in alloc */
}
if (!(dd = *dd_out = regional_alloc_zero(region,
sizeof(struct packed_rrset_data)
+ fd->count * (sizeof(size_t) + sizeof(time_t) +
sizeof(uint8_t*) + 2 + 16)))) {
log_err("out of memory");
return;
}
/* Copy attributes from A RR set. */
dd->ttl = fd->ttl;
dd->count = fd->count;
dd->rrsig_count = 0;
dd->trust = fd->trust;
dd->security = fd->security;
/*
* Synthesize AAAA records. Adjust pointers in structure.
*/
dd->rr_len =
(size_t*)((uint8_t*)dd + sizeof(struct packed_rrset_data));
dd->rr_data = (uint8_t**)&dd->rr_len[dd->count];
dd->rr_ttl = (time_t*)&dd->rr_data[dd->count];
for(i = 0; i < fd->count; ++i) {
if (fd->rr_len[i] != 6 || fd->rr_data[i][0] != 0
|| fd->rr_data[i][1] != 4) {
*dd_out = NULL;
return;
}
dd->rr_len[i] = 18;
dd->rr_data[i] =
(uint8_t*)&dd->rr_ttl[dd->count] + 18*i;
dd->rr_data[i][0] = 0;
dd->rr_data[i][1] = 16;
synthesize_aaaa(
((struct sockaddr_in6*)&dns64_env->prefix_addr)->sin6_addr.s6_addr,
sizeof(((struct sockaddr_in6*)&dns64_env->prefix_addr)->sin6_addr.s6_addr),
dns64_env->prefix_net, &fd->rr_data[i][2],
fd->rr_len[i]-2, &dd->rr_data[i][2],
dd->rr_len[i]-2);
dd->rr_ttl[i] = fd->rr_ttl[i];
}
/*
* Create synthesized AAAA RR set key. This is mostly just bookkeeping,
* nothing interesting here.
*/
if(!dk) {
log_err("no key");
*dd_out = NULL;
return;
}
dk->rk.dname = (uint8_t*)regional_alloc_init(region,
fk->rk.dname, fk->rk.dname_len);
if(!dk->rk.dname) {
log_err("out of memory");
*dd_out = NULL;
return;
}
dk->rk.type = htons(LDNS_RR_TYPE_AAAA);
memset(&dk->entry, 0, sizeof(dk->entry));
dk->entry.key = dk;
dk->entry.hash = rrset_key_hash(&dk->rk);
dk->entry.data = dd;
}
/**
* Synthesize an AAAA RR set from an A sub-query's answer and add it to the
* original empty response.
*
* \param id This module's instance ID.
* \param super Original AAAA query.
* \param qstate A query.
*/
static void
dns64_adjust_a(int id, struct module_qstate* super, struct module_qstate* qstate)
{
struct dns64_env* dns64_env = (struct dns64_env*)super->env->modinfo[id];
struct reply_info *rep, *cp;
size_t i, s;
struct packed_rrset_data* fd, *dd;
struct ub_packed_rrset_key* fk, *dk;
verbose(VERB_ALGO, "converting A answers to AAAA answers");
log_assert(super->region);
log_assert(qstate->return_msg);
log_assert(qstate->return_msg->rep);
/* If dns64-synthall is enabled, return_msg is not initialized */
if(!super->return_msg) {
super->return_msg = (struct dns_msg*)regional_alloc(
super->region, sizeof(struct dns_msg));
if(!super->return_msg)
return;
memset(super->return_msg, 0, sizeof(*super->return_msg));
super->return_msg->qinfo = super->qinfo;
}
rep = qstate->return_msg->rep;
/*
* Build the actual reply.
*/
cp = construct_reply_info_base(super->region, rep->flags, rep->qdcount,
rep->ttl, rep->prefetch_ttl, rep->serve_expired_ttl,
rep->an_numrrsets, rep->ns_numrrsets, rep->ar_numrrsets,
rep->rrset_count, rep->security, LDNS_EDE_NONE);
if(!cp)
return;
/* allocate ub_key structures special or not */
if(!reply_info_alloc_rrset_keys(cp, NULL, super->region)) {
return;
}
/* copy everything and replace A by AAAA */
for(i=0; i<cp->rrset_count; i++) {
fk = rep->rrsets[i];
dk = cp->rrsets[i];
fd = (struct packed_rrset_data*)fk->entry.data;
dk->rk = fk->rk;
dk->id = fk->id;
if(i<rep->an_numrrsets && fk->rk.type == htons(LDNS_RR_TYPE_A)) {
/* also sets dk->entry.hash */
dns64_synth_aaaa_data(fk, fd, dk, &dd, super->region, dns64_env);
if(!dd)
return;
/* Delete negative AAAA record from cache stored by
* the iterator module */
rrset_cache_remove(super->env->rrset_cache, dk->rk.dname,
dk->rk.dname_len, LDNS_RR_TYPE_AAAA,
LDNS_RR_CLASS_IN, 0);
/* Delete negative AAAA in msg cache for CNAMEs,
* stored by the iterator module */
if(i != 0) /* if not the first RR */
msg_cache_remove(super->env, dk->rk.dname,
dk->rk.dname_len, LDNS_RR_TYPE_AAAA,
LDNS_RR_CLASS_IN, 0);
} else {
dk->entry.hash = fk->entry.hash;
dk->rk.dname = (uint8_t*)regional_alloc_init(super->region,
fk->rk.dname, fk->rk.dname_len);
if(!dk->rk.dname)
return;
s = packed_rrset_sizeof(fd);
dd = (struct packed_rrset_data*)regional_alloc_init(
super->region, fd, s);
if(!dd)
return;
}
packed_rrset_ptr_fixup(dd);
dk->entry.data = (void*)dd;
}
/* Commit changes. */
super->return_msg->rep = cp;
}
/**
* Generate a response for the original IPv6 PTR query based on an IPv4 PTR
* sub-query's response.
*
* \param qstate IPv4 PTR sub-query.
* \param super Original IPv6 PTR query.
*/
static void
dns64_adjust_ptr(struct module_qstate* qstate, struct module_qstate* super)
{
struct ub_packed_rrset_key* answer;
verbose(VERB_ALGO, "adjusting PTR reply");
/* Copy the sub-query's reply to the parent. */
if (!(super->return_msg = (struct dns_msg*)regional_alloc(super->region,
sizeof(struct dns_msg))))
return;
super->return_msg->qinfo = super->qinfo;
if (!(super->return_msg->rep = reply_info_copy(qstate->return_msg->rep,
NULL, super->region)))
return;
/*
* Adjust the domain name of the answer RR set so that it matches the
* initial query's domain name.
*/
answer = reply_find_answer_rrset(&qstate->qinfo, super->return_msg->rep);
if(answer) {
answer->rk.dname = super->qinfo.qname;
answer->rk.dname_len = super->qinfo.qname_len;
}
}
/**
* This function is called when a sub-query finishes to inform the parent query.
*
* We issue two kinds of sub-queries: PTR and A.
*
* \param qstate State of the sub-query.
* \param id This module's instance ID.
* \param super State of the super-query.
*/
void
dns64_inform_super(struct module_qstate* qstate, int id,
struct module_qstate* super)
{
struct dns64_qstate* super_dq = (struct dns64_qstate*)super->minfo[id];
log_query_info(VERB_ALGO, "dns64: inform_super, sub is",
&qstate->qinfo);
log_query_info(VERB_ALGO, "super is", &super->qinfo);
/*
* Signal that the sub-query is finished, no matter whether we are
* successful or not. This lets the state machine terminate.
*/
if(!super_dq) {
super_dq = (struct dns64_qstate*)regional_alloc(super->region,
sizeof(*super_dq));
if(!super_dq) {
log_err("out of memory");
super->return_rcode = LDNS_RCODE_SERVFAIL;
super->return_msg = NULL;
return;
}
super->minfo[id] = super_dq;
memset(super_dq, 0, sizeof(*super_dq));
super_dq->started_no_cache_store = super->no_cache_store;
}
super_dq->state = DNS64_SUBQUERY_FINISHED;
/* If there is no successful answer, we're done.
* Guarantee that we have at least a NOERROR reply further on. */
if(qstate->return_rcode != LDNS_RCODE_NOERROR
|| !qstate->return_msg
|| !qstate->return_msg->rep) {
return;
}
/* When no A record is found for synthesis fall back to AAAA again. */
if(qstate->qinfo.qtype == LDNS_RR_TYPE_A &&
!reply_find_answer_rrset(&qstate->qinfo,
qstate->return_msg->rep)) {
super_dq->state = DNS64_INTERNAL_QUERY;
return;
}
/* Use return code from A query in response to client. */
if (super->return_rcode != LDNS_RCODE_NOERROR)
super->return_rcode = qstate->return_rcode;
/* Generate a response suitable for the original query. */
if (qstate->qinfo.qtype == LDNS_RR_TYPE_A) {
dns64_adjust_a(id, super, qstate);
} else {
log_assert(qstate->qinfo.qtype == LDNS_RR_TYPE_PTR);
dns64_adjust_ptr(qstate, super);
}
/* Store the generated response in cache. */
if ( (!super_dq || !super_dq->started_no_cache_store) &&
!dns_cache_store(super->env, &super->qinfo, super->return_msg->rep,
0, 0, 0, NULL, super->query_flags, qstate->qstarttime))
log_err("out of memory");
}
/**
* Clear module-specific data from query state. Since we do not allocate memory,
* it's just a matter of setting a pointer to NULL.
*
* \param qstate Query state.
* \param id This module's instance ID.
*/
void
dns64_clear(struct module_qstate* qstate, int id)
{
qstate->minfo[id] = NULL;
}
/**
* Returns the amount of global memory that this module uses, not including
* per-query data.
*
* \param env Module environment.
* \param id This module's instance ID.
*/
size_t
dns64_get_mem(struct module_env* env, int id)
{
struct dns64_env* dns64_env = (struct dns64_env*)env->modinfo[id];
if (!dns64_env)
return 0;
return sizeof(*dns64_env);
}
/**
* The dns64 function block.
*/
static struct module_func_block dns64_block = {
"dns64",
&dns64_init, &dns64_deinit, &dns64_operate, &dns64_inform_super,
&dns64_clear, &dns64_get_mem
};
/**
* Function for returning the above function block.
*/
struct module_func_block *
dns64_get_funcblock(void)
{
return &dns64_block;
}
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