GopherProxy

/*
* cachedb/cachedb.c - cache from a database external to the program module
*
* Copyright (c) 2016, NLnet Labs. 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 the NLNET LABS 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 COPYRIGHT
* HOLDER 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 uses an external database to cache
* dns responses.
*/

#include "config.h"
#ifdef USE_CACHEDB
#include "cachedb/cachedb.h"
#include "cachedb/redis.h"
#include "util/regional.h"
#include "util/net_help.h"
#include "util/config_file.h"
#include "util/data/dname.h"
#include "util/data/msgreply.h"
#include "util/data/msgencode.h"
#include "services/cache/dns.h"
#include "services/mesh.h"
#include "services/modstack.h"
#include "validator/val_neg.h"
#include "validator/val_secalgo.h"
#include "iterator/iter_utils.h"
#include "sldns/parseutil.h"
#include "sldns/wire2str.h"
#include "sldns/sbuffer.h"

/* header file for htobe64 */
#ifdef HAVE_ENDIAN_H
# include <endian.h>
#endif
#ifdef HAVE_SYS_ENDIAN_H
# include <sys/endian.h>
#endif

#ifndef HAVE_HTOBE64
# ifdef HAVE_LIBKERN_OSBYTEORDER_H
/* In practice this is specific to MacOS X. We assume it doesn't have
* htobe64/be64toh but has alternatives with a different name. */
# include <libkern/OSByteOrder.h>
# define htobe64(x) OSSwapHostToBigInt64(x)
# define be64toh(x) OSSwapBigToHostInt64(x)
# else
/* not OSX */
/* Some compilers do not define __BYTE_ORDER__, like IBM XLC on AIX */
# if __BIG_ENDIAN__
# define be64toh(n) (n)
# define htobe64(n) (n)
# else
# define be64toh(n) (((uint64_t)htonl((n) & 0xFFFFFFFF) << 32) | htonl((n) >> 32))
# define htobe64(n) (((uint64_t)htonl((n) & 0xFFFFFFFF) << 32) | htonl((n) >> 32))
# endif /* _ENDIAN */
# endif /* HAVE_LIBKERN_OSBYTEORDER_H */
#endif /* HAVE_BE64TOH */

/** the unit test testframe for cachedb, its module state contains
* a cache for a couple queries (in memory). */
struct testframe_moddata {
/** lock for mutex */
lock_basic_type lock;
/** key for single stored data element, NULL if none */
char* stored_key;
/** data for single stored data element, NULL if none */
uint8_t* stored_data;
/** length of stored data */
size_t stored_datalen;
};

static int
testframe_init(struct module_env* env, struct cachedb_env* cachedb_env)
{
struct testframe_moddata* d;
verbose(VERB_ALGO, "testframe_init");
d = (struct testframe_moddata*)calloc(1,
sizeof(struct testframe_moddata));
cachedb_env->backend_data = (void*)d;
if(!cachedb_env->backend_data) {
log_err("out of memory");
return 0;
}
/* Register an EDNS option (65534) to bypass the worker cache lookup
* for testing */
if(!edns_register_option(LDNS_EDNS_UNBOUND_CACHEDB_TESTFRAME_TEST,
1 /* bypass cache */,
0 /* no aggregation */, env)) {
log_err("testframe_init, could not register test opcode");
free(d);
return 0;
}
lock_basic_init(&d->lock);
lock_protect(&d->lock, d, sizeof(*d));
return 1;
}

static void
testframe_deinit(struct module_env* env, struct cachedb_env* cachedb_env)
{
struct testframe_moddata* d = (struct testframe_moddata*)
cachedb_env->backend_data;
(void)env;
verbose(VERB_ALGO, "testframe_deinit");
if(!d)
return;
lock_basic_destroy(&d->lock);
free(d->stored_key);
free(d->stored_data);
free(d);
}

static int
testframe_lookup(struct module_env* env, struct cachedb_env* cachedb_env,
char* key, struct sldns_buffer* result_buffer)
{
struct testframe_moddata* d = (struct testframe_moddata*)
cachedb_env->backend_data;
(void)env;
verbose(VERB_ALGO, "testframe_lookup of %s", key);
lock_basic_lock(&d->lock);
if(d->stored_key && strcmp(d->stored_key, key) == 0) {
if(d->stored_datalen > sldns_buffer_capacity(result_buffer)) {
lock_basic_unlock(&d->lock);
return 0; /* too large */
}
verbose(VERB_ALGO, "testframe_lookup found %d bytes",
(int)d->stored_datalen);
sldns_buffer_clear(result_buffer);
sldns_buffer_write(result_buffer, d->stored_data,
d->stored_datalen);
sldns_buffer_flip(result_buffer);
lock_basic_unlock(&d->lock);
return 1;
}
lock_basic_unlock(&d->lock);
return 0;
}

static void
testframe_store(struct module_env* env, struct cachedb_env* cachedb_env,
char* key, uint8_t* data, size_t data_len, time_t ATTR_UNUSED(ttl))
{
struct testframe_moddata* d = (struct testframe_moddata*)
cachedb_env->backend_data;
(void)env;
lock_basic_lock(&d->lock);
verbose(VERB_ALGO, "testframe_store %s (%d bytes)", key, (int)data_len);

/* free old data element (if any) */
free(d->stored_key);
d->stored_key = NULL;
free(d->stored_data);
d->stored_data = NULL;
d->stored_datalen = 0;

d->stored_data = memdup(data, data_len);
if(!d->stored_data) {
lock_basic_unlock(&d->lock);
log_err("out of memory");
return;
}
d->stored_datalen = data_len;
d->stored_key = strdup(key);
if(!d->stored_key) {
free(d->stored_data);
d->stored_data = NULL;
d->stored_datalen = 0;
lock_basic_unlock(&d->lock);
return;
}
lock_basic_unlock(&d->lock);
/* (key,data) successfully stored */
}

/** The testframe backend is for unit tests */
static struct cachedb_backend testframe_backend = { "testframe",
testframe_init, testframe_deinit, testframe_lookup, testframe_store
};

/** find a particular backend from possible backends */
static struct cachedb_backend*
cachedb_find_backend(const char* str)
{
#ifdef USE_REDIS
if(strcmp(str, redis_backend.name) == 0)
return &redis_backend;
#endif
if(strcmp(str, testframe_backend.name) == 0)
return &testframe_backend;
/* TODO add more backends here */
return NULL;
}

/** apply configuration to cachedb module 'global' state */
static int
cachedb_apply_cfg(struct cachedb_env* cachedb_env, struct config_file* cfg)
{
const char* backend_str = cfg->cachedb_backend;
if(!backend_str || *backend_str==0)
return 1;
cachedb_env->backend = cachedb_find_backend(backend_str);
if(!cachedb_env->backend) {
log_err("cachedb: cannot find backend name '%s'", backend_str);
return 0;
}

/* TODO see if more configuration needs to be applied or not */
return 1;
}

int
cachedb_init(struct module_env* env, int id)
{
struct cachedb_env* cachedb_env = (struct cachedb_env*)calloc(1,
sizeof(struct cachedb_env));
if(!cachedb_env) {
log_err("malloc failure");
return 0;
}
env->modinfo[id] = (void*)cachedb_env;
if(!cachedb_apply_cfg(cachedb_env, env->cfg)) {
log_err("cachedb: could not apply configuration settings.");
free(cachedb_env);
env->modinfo[id] = NULL;
return 0;
}
/* see if a backend is selected */
if(!cachedb_env->backend || !cachedb_env->backend->name)
return 1;
if(!(*cachedb_env->backend->init)(env, cachedb_env)) {
log_err("cachedb: could not init %s backend",
cachedb_env->backend->name);
free(cachedb_env);
env->modinfo[id] = NULL;
return 0;
}
cachedb_env->enabled = 1;
return 1;
}

void
cachedb_deinit(struct module_env* env, int id)
{
struct cachedb_env* cachedb_env;
if(!env || !env->modinfo[id])
return;
cachedb_env = (struct cachedb_env*)env->modinfo[id];
if(cachedb_env->enabled) {
(*cachedb_env->backend->deinit)(env, cachedb_env);
}
free(cachedb_env);
env->modinfo[id] = NULL;
}

/** new query for cachedb */
static int
cachedb_new(struct module_qstate* qstate, int id)
{
struct cachedb_qstate* iq = (struct cachedb_qstate*)regional_alloc(
qstate->region, sizeof(struct cachedb_qstate));
qstate->minfo[id] = iq;
if(!iq)
return 0;
memset(iq, 0, sizeof(*iq));
/* initialise it */
/* TODO */

return 1;
}

/**
* Return an error
* @param qstate: our query state
* @param id: module id
* @param rcode: error code (DNS errcode).
* @return: 0 for use by caller, to make notation easy, like:
* return error_response(..).
*/
static int
error_response(struct module_qstate* qstate, int id, int rcode)
{
verbose(VERB_QUERY, "return error response %s",
sldns_lookup_by_id(sldns_rcodes, rcode)?
sldns_lookup_by_id(sldns_rcodes, rcode)->name:"??");
qstate->return_rcode = rcode;
qstate->return_msg = NULL;
qstate->ext_state[id] = module_finished;
return 0;
}

/**
* Hash the query name, type, class and dbacess-secret into lookup buffer.
* @param qinfo: query info
* @param env: with env->cfg with secret.
* @param buf: returned buffer with hash to lookup
* @param len: length of the buffer.
*/
static void
calc_hash(struct query_info* qinfo, struct module_env* env, char* buf,
size_t len)
{
uint8_t clear[1024];
size_t clen = 0;
uint8_t hash[CACHEDB_HASHSIZE/8];
const char* hex = "0123456789ABCDEF";
const char* secret = env->cfg->cachedb_secret;
size_t i;

/* copy the hash info into the clear buffer */
if(clen + qinfo->qname_len < sizeof(clear)) {
memmove(clear+clen, qinfo->qname, qinfo->qname_len);
query_dname_tolower(clear+clen);
clen += qinfo->qname_len;
}
if(clen + 4 < sizeof(clear)) {
uint16_t t = htons(qinfo->qtype);
uint16_t c = htons(qinfo->qclass);
memmove(clear+clen, &t, 2);
memmove(clear+clen+2, &c, 2);
clen += 4;
}
if(secret && secret[0] && clen + strlen(secret) < sizeof(clear)) {
memmove(clear+clen, secret, strlen(secret));
clen += strlen(secret);
}

/* hash the buffer */
secalgo_hash_sha256(clear, clen, hash);
#ifdef HAVE_EXPLICIT_BZERO
explicit_bzero(clear, clen);
#else
memset(clear, 0, clen);
#endif

/* hex encode output for portability (some online dbs need
* no nulls, no control characters, and so on) */
log_assert(len >= sizeof(hash)*2 + 1);
(void)len;
for(i=0; i<sizeof(hash); i++) {
buf[i*2] = hex[(hash[i]&0xf0)>>4];
buf[i*2+1] = hex[hash[i]&0x0f];
}
buf[sizeof(hash)*2] = 0;
}

/** convert data from return_msg into the data buffer */
static int
prep_data(struct module_qstate* qstate, struct sldns_buffer* buf)
{
uint64_t timestamp, expiry;
size_t oldlim;
struct edns_data edns;
memset(&edns, 0, sizeof(edns));
edns.edns_present = 1;
edns.bits = EDNS_DO;
edns.ext_rcode = 0;
edns.edns_version = EDNS_ADVERTISED_VERSION;
edns.udp_size = EDNS_ADVERTISED_SIZE;

if(!qstate->return_msg || !qstate->return_msg->rep)
return 0;
/* do not store failures like SERVFAIL in the cachedb, this avoids
* overwriting expired, valid, content with broken content. */
if(FLAGS_GET_RCODE(qstate->return_msg->rep->flags) !=
LDNS_RCODE_NOERROR &&
FLAGS_GET_RCODE(qstate->return_msg->rep->flags) !=
LDNS_RCODE_NXDOMAIN &&
FLAGS_GET_RCODE(qstate->return_msg->rep->flags) !=
LDNS_RCODE_YXDOMAIN)
return 0;
/* We don't store the reply if its TTL is 0 unless serve-expired is
* enabled. Such a reply won't be reusable and simply be a waste for
* the backend. It's also compatible with the default behavior of
* dns_cache_store_msg(). */
if(qstate->return_msg->rep->ttl == 0 &&
!qstate->env->cfg->serve_expired)
return 0;

/* The EDE is added to the out-list so it is encoded in the cached message */
if (qstate->env->cfg->ede && qstate->return_msg->rep->reason_bogus != LDNS_EDE_NONE) {
edns_opt_list_append_ede(&edns.opt_list_out, qstate->env->scratch,
qstate->return_msg->rep->reason_bogus,
qstate->return_msg->rep->reason_bogus_str);
}

if(verbosity >= VERB_ALGO)
log_dns_msg("cachedb encoding", &qstate->return_msg->qinfo,
qstate->return_msg->rep);
if(!reply_info_answer_encode(&qstate->return_msg->qinfo,
qstate->return_msg->rep, 0, qstate->query_flags,
buf, 0, 1, qstate->env->scratch, 65535, &edns, 1, 0))
return 0;

/* TTLs in the return_msg are relative to time(0) so we have to
* store that, we also store the smallest ttl in the packet+time(0)
* as the packet expiry time */
/* qstate->return_msg->rep->ttl contains that relative shortest ttl */
timestamp = (uint64_t)*qstate->env->now;
expiry = timestamp + (uint64_t)qstate->return_msg->rep->ttl;
timestamp = htobe64(timestamp);
expiry = htobe64(expiry);
oldlim = sldns_buffer_limit(buf);
if(oldlim + sizeof(timestamp)+sizeof(expiry) >=
sldns_buffer_capacity(buf))
return 0; /* doesn't fit. */
sldns_buffer_set_limit(buf, oldlim + sizeof(timestamp)+sizeof(expiry));
sldns_buffer_write_at(buf, oldlim, &timestamp, sizeof(timestamp));
sldns_buffer_write_at(buf, oldlim+sizeof(timestamp), &expiry,
sizeof(expiry));

return 1;
}

/** check expiry, return true if matches OK */
static int
good_expiry_and_qinfo(struct module_qstate* qstate, struct sldns_buffer* buf)
{
uint64_t expiry;
/* the expiry time is the last bytes of the buffer */
if(sldns_buffer_limit(buf) < sizeof(expiry))
return 0;
sldns_buffer_read_at(buf, sldns_buffer_limit(buf)-sizeof(expiry),
&expiry, sizeof(expiry));
expiry = be64toh(expiry);

/* Check if we are allowed to return expired entries:
* - serve_expired needs to be set
* - if SERVE_EXPIRED_TTL is set make sure that the record is not older
* than that. */
if((time_t)expiry < *qstate->env->now &&
(!qstate->env->cfg->serve_expired ||
(SERVE_EXPIRED_TTL &&
*qstate->env->now - (time_t)expiry > SERVE_EXPIRED_TTL)))
return 0;

return 1;
}

/* Adjust the TTL of the given RRset by 'subtract'. If 'subtract' is
* negative, set the TTL to 0. */
static void
packed_rrset_ttl_subtract(struct packed_rrset_data* data, time_t subtract)
{
size_t i;
size_t total = data->count + data->rrsig_count;
if(subtract >= 0 && data->ttl > subtract)
data->ttl -= subtract;
else data->ttl = 0;
for(i=0; i<total; i++) {
if(subtract >= 0 && data->rr_ttl[i] > subtract)
data->rr_ttl[i] -= subtract;
else data->rr_ttl[i] = 0;
}
data->ttl_add = (subtract < data->ttl_add) ? (data->ttl_add - subtract) : 0;
}

/* Adjust the TTL of a DNS message and its RRs by 'adjust'. If 'adjust' is
* negative, set the TTLs to 0. */
static void
adjust_msg_ttl(struct dns_msg* msg, time_t adjust)
{
size_t i;
if(adjust >= 0 && msg->rep->ttl > adjust)
msg->rep->ttl -= adjust;
else
msg->rep->ttl = 0;
msg->rep->prefetch_ttl = PREFETCH_TTL_CALC(msg->rep->ttl);
msg->rep->serve_expired_ttl = msg->rep->ttl + SERVE_EXPIRED_TTL;

for(i=0; i<msg->rep->rrset_count; i++) {
packed_rrset_ttl_subtract((struct packed_rrset_data*)msg->
rep->rrsets[i]->entry.data, adjust);
}
}

/* Set the TTL of the given RRset to fixed value. */
static void
packed_rrset_ttl_set(struct packed_rrset_data* data, time_t ttl)
{
size_t i;
size_t total = data->count + data->rrsig_count;
data->ttl = ttl;
for(i=0; i<total; i++) {
data->rr_ttl[i] = ttl;
}
data->ttl_add = 0;
}

/* Set the TTL of a DNS message and its RRs by to a fixed value. */
static void
set_msg_ttl(struct dns_msg* msg, time_t ttl)
{
size_t i;
msg->rep->ttl = ttl;
msg->rep->prefetch_ttl = PREFETCH_TTL_CALC(msg->rep->ttl);
msg->rep->serve_expired_ttl = msg->rep->ttl + SERVE_EXPIRED_TTL;

for(i=0; i<msg->rep->rrset_count; i++) {
packed_rrset_ttl_set((struct packed_rrset_data*)msg->
rep->rrsets[i]->entry.data, ttl);
}
}

/** convert dns message in buffer to return_msg */
static int
parse_data(struct module_qstate* qstate, struct sldns_buffer* buf,
int* msg_expired)
{
struct msg_parse* prs;
struct edns_data edns;
struct edns_option* ede;
uint64_t timestamp, expiry;
time_t adjust;
size_t lim = sldns_buffer_limit(buf);
if(lim < LDNS_HEADER_SIZE+sizeof(timestamp)+sizeof(expiry))
return 0; /* too short */

/* remove timestamp and expiry from end */
sldns_buffer_read_at(buf, lim-sizeof(expiry), &expiry, sizeof(expiry));
sldns_buffer_read_at(buf, lim-sizeof(expiry)-sizeof(timestamp),
&timestamp, sizeof(timestamp));
expiry = be64toh(expiry);
timestamp = be64toh(timestamp);

/* parse DNS packet */
regional_free_all(qstate->env->scratch);
prs = (struct msg_parse*)regional_alloc(qstate->env->scratch,
sizeof(struct msg_parse));
if(!prs)
return 0; /* out of memory */
memset(prs, 0, sizeof(*prs));
memset(&edns, 0, sizeof(edns));
sldns_buffer_set_limit(buf, lim - sizeof(expiry)-sizeof(timestamp));
if(parse_packet(buf, prs, qstate->env->scratch) != LDNS_RCODE_NOERROR) {
sldns_buffer_set_limit(buf, lim);
return 0;
}
if(parse_extract_edns_from_response_msg(prs, &edns, qstate->env->scratch) !=
LDNS_RCODE_NOERROR) {
sldns_buffer_set_limit(buf, lim);
return 0;
}

qstate->return_msg = dns_alloc_msg(buf, prs, qstate->region);
sldns_buffer_set_limit(buf, lim);
if(!qstate->return_msg)
return 0;

/* We find the EDE in the in-list after parsing */
if(qstate->env->cfg->ede &&
(ede = edns_opt_list_find(edns.opt_list_in, LDNS_EDNS_EDE))) {
if(ede->opt_len >= 2) {
qstate->return_msg->rep->reason_bogus =
sldns_read_uint16(ede->opt_data);
}
/* allocate space and store the error string and it's size */
if(ede->opt_len > 2) {
size_t ede_len = ede->opt_len - 2;
qstate->return_msg->rep->reason_bogus_str = regional_alloc(
qstate->region, sizeof(char) * (ede_len+1));
memcpy(qstate->return_msg->rep->reason_bogus_str,
ede->opt_data+2, ede_len);
qstate->return_msg->rep->reason_bogus_str[ede_len] = 0;
}
}

qstate->return_rcode = LDNS_RCODE_NOERROR;

/* see how much of the TTL expired, and remove it */
if(*qstate->env->now <= (time_t)timestamp) {
verbose(VERB_ALGO, "cachedb msg adjust by zero");
return 1; /* message from the future (clock skew?) */
}
adjust = *qstate->env->now - (time_t)timestamp;
if(qstate->return_msg->rep->ttl < adjust) {
verbose(VERB_ALGO, "cachedb msg expired");
*msg_expired = 1;
/* If serve-expired is enabled, we still use an expired message
* setting the TTL to 0. */
if(!qstate->env->cfg->serve_expired ||
(FLAGS_GET_RCODE(qstate->return_msg->rep->flags)
!= LDNS_RCODE_NOERROR &&
FLAGS_GET_RCODE(qstate->return_msg->rep->flags)
!= LDNS_RCODE_NXDOMAIN &&
FLAGS_GET_RCODE(qstate->return_msg->rep->flags)
!= LDNS_RCODE_YXDOMAIN))
return 0; /* message expired */
else
adjust = -1;
}
verbose(VERB_ALGO, "cachedb msg adjusted down by %d", (int)adjust);
adjust_msg_ttl(qstate->return_msg, adjust);
if(qstate->env->cfg->aggressive_nsec) {
limit_nsec_ttl(qstate->return_msg);
}

/* Similar to the unbound worker, if serve-expired is enabled and
* the msg would be considered to be expired, mark the state so a
* refetch will be scheduled. The comparison between 'expiry' and
* 'now' should be redundant given how these values were calculated,
* but we check it just in case as does good_expiry_and_qinfo(). */
if(qstate->env->cfg->serve_expired &&
!qstate->env->cfg->serve_expired_client_timeout &&
(adjust == -1 || (time_t)expiry < *qstate->env->now)) {
qstate->need_refetch = 1;
}

return 1;
}

/**
* Lookup the qstate.qinfo in extcache, store in qstate.return_msg.
* return true if lookup was successful.
*/
static int
cachedb_extcache_lookup(struct module_qstate* qstate, struct cachedb_env* ie,
int* msg_expired)
{
char key[(CACHEDB_HASHSIZE/8)*2+1];
calc_hash(&qstate->qinfo, qstate->env, key, sizeof(key));

/* call backend to fetch data for key into scratch buffer */
if( !(*ie->backend->lookup)(qstate->env, ie, key,
qstate->env->scratch_buffer)) {
return 0;
}

/* check expiry date and check if query-data matches */
if( !good_expiry_and_qinfo(qstate, qstate->env->scratch_buffer) ) {
return 0;
}

/* parse dns message into return_msg */
if( !parse_data(qstate, qstate->env->scratch_buffer, msg_expired) ) {
return 0;
}
return 1;
}

/**
* Store the qstate.return_msg in extcache for key qstate.info
*/
static void
cachedb_extcache_store(struct module_qstate* qstate, struct cachedb_env* ie)
{
char key[(CACHEDB_HASHSIZE/8)*2+1];
calc_hash(&qstate->qinfo, qstate->env, key, sizeof(key));

/* prepare data in scratch buffer */
if(!prep_data(qstate, qstate->env->scratch_buffer))
return;

/* call backend */
(*ie->backend->store)(qstate->env, ie, key,
sldns_buffer_begin(qstate->env->scratch_buffer),
sldns_buffer_limit(qstate->env->scratch_buffer),
qstate->return_msg->rep->ttl);
}

/**
* See if unbound's internal cache can answer the query
*/
static int
cachedb_intcache_lookup(struct module_qstate* qstate, struct cachedb_env* cde)
{
uint8_t dpname_storage[LDNS_MAX_DOMAINLEN+1];
uint8_t* dpname=NULL;
size_t dpnamelen=0;
struct dns_msg* msg;
/* for testframe bypass this lookup */
if(cde->backend == &testframe_backend) {
return 0;
}
if(iter_stub_fwd_no_cache(qstate, &qstate->qinfo,
&dpname, &dpnamelen, dpname_storage, sizeof(dpname_storage)))
return 0; /* no cache for these queries */
msg = dns_cache_lookup(qstate->env, qstate->qinfo.qname,
qstate->qinfo.qname_len, qstate->qinfo.qtype,
qstate->qinfo.qclass, qstate->query_flags,
qstate->region, qstate->env->scratch,
1, /* no partial messages with only a CNAME */
dpname, dpnamelen
);
if(!msg && qstate->env->neg_cache &&
iter_qname_indicates_dnssec(qstate->env, &qstate->qinfo)) {
/* lookup in negative cache; may result in
* NOERROR/NODATA or NXDOMAIN answers that need validation */
msg = val_neg_getmsg(qstate->env->neg_cache, &qstate->qinfo,
qstate->region, qstate->env->rrset_cache,
qstate->env->scratch_buffer,
*qstate->env->now, 1/*add SOA*/, NULL,
qstate->env->cfg);
}
if(!msg)
return 0;
/* this is the returned msg */
qstate->return_rcode = LDNS_RCODE_NOERROR;
qstate->return_msg = msg;
return 1;
}

/**
* Store query into the internal cache of unbound.
*/
static void
cachedb_intcache_store(struct module_qstate* qstate, int msg_expired)
{
uint32_t store_flags = qstate->query_flags;
int serve_expired = qstate->env->cfg->serve_expired;

if(qstate->env->cfg->serve_expired)
store_flags |= DNSCACHE_STORE_ZEROTTL;
if(!qstate->return_msg)
return;
if(serve_expired && msg_expired) {
/* Set TTLs to a value such that value + *env->now is
* going to be now-3 seconds. Making it expired
* in the cache. */
set_msg_ttl(qstate->return_msg, (time_t)-3);
/* The expired entry does not get checked by the validator
* and we need a validation value for it. */
if(qstate->env->cfg->cachedb_check_when_serve_expired)
qstate->return_msg->rep->security = sec_status_insecure;
}
(void)dns_cache_store(qstate->env, &qstate->qinfo,
qstate->return_msg->rep, 0, qstate->prefetch_leeway, 0,
qstate->region, store_flags, qstate->qstarttime,
qstate->is_valrec);
if(serve_expired && msg_expired) {
if(qstate->env->cfg->serve_expired_client_timeout) {
/* No expired response from the query state, the
* query resolution needs to continue and it can
* pick up the expired result after the timer out
* of cache. */
return;
}
/* set TTLs to zero again */
adjust_msg_ttl(qstate->return_msg, -1);
/* Send serve expired responses based on the cachedb
* returned message, that was just stored in the cache.
* It can then continue to work on this query. */
mesh_respond_serve_expired(qstate->mesh_info);
}
}

/**
* Handle a cachedb module event with a query
* @param qstate: query state (from the mesh), passed between modules.
* contains qstate->env module environment with global caches and so on.
* @param iq: query state specific for this module. per-query.
* @param ie: environment specific for this module. global.
* @param id: module id.
*/
static void
cachedb_handle_query(struct module_qstate* qstate,
struct cachedb_qstate* ATTR_UNUSED(iq),
struct cachedb_env* ie, int id)
{
int msg_expired = 0;
qstate->is_cachedb_answer = 0;
/* check if we are enabled, and skip if so */
if(!ie->enabled) {
/* pass request to next module */
qstate->ext_state[id] = module_wait_module;
return;
}

if(qstate->blacklist || qstate->no_cache_lookup) {
/* cache is blacklisted or we are instructed from edns to not look */
/* pass request to next module */
qstate->ext_state[id] = module_wait_module;
return;
}

/* lookup inside unbound's internal cache.
* This does not look for expired entries. */
if(cachedb_intcache_lookup(qstate, ie)) {
if(verbosity >= VERB_ALGO) {
if(qstate->return_msg->rep)
log_dns_msg("cachedb internal cache lookup",
&qstate->return_msg->qinfo,
qstate->return_msg->rep);
else log_info("cachedb internal cache lookup: rcode %s",
sldns_lookup_by_id(sldns_rcodes, qstate->return_rcode)
?sldns_lookup_by_id(sldns_rcodes, qstate->return_rcode)->name
:"??");
}
/* we are done with the query */
qstate->ext_state[id] = module_finished;
return;
}

/* ask backend cache to see if we have data */
if(cachedb_extcache_lookup(qstate, ie, &msg_expired)) {
if(verbosity >= VERB_ALGO)
log_dns_msg(ie->backend->name,
&qstate->return_msg->qinfo,
qstate->return_msg->rep);
/* store this result in internal cache */
cachedb_intcache_store(qstate, msg_expired);
/* In case we have expired data but there is a client timer for expired
* answers, pass execution to next module in order to try updating the
* data first.
*/
if(qstate->env->cfg->serve_expired && msg_expired) {
qstate->return_msg = NULL;
qstate->ext_state[id] = module_wait_module;
/* The expired reply is sent with
* mesh_respond_serve_expired, and so
* the need_refetch is not used. */
qstate->need_refetch = 0;
return;
}
if(qstate->need_refetch && qstate->serve_expired_data &&
qstate->serve_expired_data->timer) {
qstate->return_msg = NULL;
qstate->ext_state[id] = module_wait_module;
return;
}
qstate->is_cachedb_answer = 1;
/* we are done with the query */
qstate->ext_state[id] = module_finished;
return;
}

if(qstate->serve_expired_data &&
qstate->env->cfg->cachedb_check_when_serve_expired &&
!qstate->env->cfg->serve_expired_client_timeout) {
/* Reply with expired data if any to client, because cachedb
* also has no useful, current data */
mesh_respond_serve_expired(qstate->mesh_info);
}

/* no cache fetches */
/* pass request to next module */
qstate->ext_state[id] = module_wait_module;
}

/**
* Handle a cachedb module event with a response from the iterator.
* @param qstate: query state (from the mesh), passed between modules.
* contains qstate->env module environment with global caches and so on.
* @param iq: query state specific for this module. per-query.
* @param ie: environment specific for this module. global.
* @param id: module id.
*/
static void
cachedb_handle_response(struct module_qstate* qstate,
struct cachedb_qstate* ATTR_UNUSED(iq), struct cachedb_env* ie, int id)
{
qstate->is_cachedb_answer = 0;
/* check if we are not enabled or instructed to not cache, and skip */
if(!ie->enabled || qstate->no_cache_store) {
/* we are done with the query */
qstate->ext_state[id] = module_finished;
return;
}
if(qstate->env->cfg->cachedb_no_store) {
/* do not store the item in the external cache */
qstate->ext_state[id] = module_finished;
return;
}

/* store the item into the backend cache */
cachedb_extcache_store(qstate, ie);

/* we are done with the query */
qstate->ext_state[id] = module_finished;
}

void
cachedb_operate(struct module_qstate* qstate, enum module_ev event, int id,
struct outbound_entry* outbound)
{
struct cachedb_env* ie = (struct cachedb_env*)qstate->env->modinfo[id];
struct cachedb_qstate* iq = (struct cachedb_qstate*)qstate->minfo[id];
verbose(VERB_QUERY, "cachedb[module %d] operate: extstate:%s event:%s",
id, strextstate(qstate->ext_state[id]), strmodulevent(event));
if(iq) log_query_info(VERB_QUERY, "cachedb operate: query",
&qstate->qinfo);

/* perform cachedb state machine */
if((event == module_event_new || event == module_event_pass) &&
iq == NULL) {
if(!cachedb_new(qstate, id)) {
(void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
return;
}
iq = (struct cachedb_qstate*)qstate->minfo[id];
}
if(iq && (event == module_event_pass || event == module_event_new)) {
cachedb_handle_query(qstate, iq, ie, id);
return;
}
if(iq && (event == module_event_moddone)) {
cachedb_handle_response(qstate, iq, ie, id);
return;
}
if(iq && outbound) {
/* cachedb does not need to process responses at this time
* ignore it.
cachedb_process_response(qstate, iq, ie, id, outbound, event);
*/
return;
}
if(event == module_event_error) {
verbose(VERB_ALGO, "got called with event error, giving up");
(void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
return;
}
if(!iq && (event == module_event_moddone)) {
/* during priming, module done but we never started */
qstate->ext_state[id] = module_finished;
return;
}

log_err("bad event for cachedb");
(void)error_response(qstate, id, LDNS_RCODE_SERVFAIL);
}

void
cachedb_inform_super(struct module_qstate* ATTR_UNUSED(qstate),
int ATTR_UNUSED(id), struct module_qstate* ATTR_UNUSED(super))
{
/* cachedb does not use subordinate requests at this time */
verbose(VERB_ALGO, "cachedb inform_super was called");
}

void
cachedb_clear(struct module_qstate* qstate, int id)
{
struct cachedb_qstate* iq;
if(!qstate)
return;
iq = (struct cachedb_qstate*)qstate->minfo[id];
if(iq) {
/* free contents of iq */
/* TODO */
}
qstate->minfo[id] = NULL;
}

size_t
cachedb_get_mem(struct module_env* env, int id)
{
struct cachedb_env* ie = (struct cachedb_env*)env->modinfo[id];
if(!ie)
return 0;
return sizeof(*ie); /* TODO - more mem */
}

/**
* The cachedb function block
*/
static struct module_func_block cachedb_block = {
"cachedb",
NULL, NULL, &cachedb_init, &cachedb_deinit, &cachedb_operate,
&cachedb_inform_super, &cachedb_clear, &cachedb_get_mem
};

struct module_func_block*
cachedb_get_funcblock(void)
{
return &cachedb_block;
}

int
cachedb_is_enabled(struct module_stack* mods, struct module_env* env)
{
struct cachedb_env* ie;
int id = modstack_find(mods, "cachedb");
if(id == -1)
return 0;
ie = (struct cachedb_env*)env->modinfo[id];
if(ie && ie->enabled)
return 1;
return 0;
}

void cachedb_msg_remove(struct module_qstate* qstate)
{
cachedb_msg_remove_qinfo(qstate->env, &qstate->qinfo);
}

void cachedb_msg_remove_qinfo(struct module_env* env, struct query_info* qinfo)
{
char key[(CACHEDB_HASHSIZE/8)*2+1];
int id = modstack_find(env->modstack, "cachedb");
struct cachedb_env* ie = (struct cachedb_env*)env->modinfo[id];

log_query_info(VERB_ALGO, "cachedb msg remove", qinfo);
calc_hash(qinfo, env, key, sizeof(key));
sldns_buffer_clear(env->scratch_buffer);
sldns_buffer_write_u32(env->scratch_buffer, 0);
sldns_buffer_flip(env->scratch_buffer);

/* call backend */
(*ie->backend->store)(env, ie, key,
sldns_buffer_begin(env->scratch_buffer),
sldns_buffer_limit(env->scratch_buffer),
0);
}
#endif /* USE_CACHEDB */