2 * cachedb/redis.c - cachedb redis module
4 * Copyright (c) 2018, NLnet Labs. All rights reserved.
6 * This software is open source.
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9 * modification, are permitted provided that the following conditions
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13 * this list of conditions and the following disclaimer.
15 * Redistributions in binary form must reproduce the above copyright notice,
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23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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39 * This file contains a module that uses the redis database to cache
45 #include "cachedb/redis.h"
46 #include "cachedb/cachedb.h"
47 #include "util/alloc.h"
48 #include "util/config_file.h"
49 #include "sldns/sbuffer.h"
52 #include "hiredis/hiredis.h"
54 struct redis_moddata {
55 redisContext** ctxs; /* thread-specific redis contexts */
56 int numctxs; /* number of ctx entries */
57 const char* server_host; /* server's IP address or host name */
58 int server_port; /* server's TCP port */
59 struct timeval timeout; /* timeout for connection setup and commands */
62 static redisReply* redis_command(struct module_env*, struct cachedb_env*,
63 const char*, const uint8_t*, size_t);
66 redis_connect(const struct redis_moddata* moddata)
70 ctx = redisConnectWithTimeout(moddata->server_host,
71 moddata->server_port, moddata->timeout);
72 if(!ctx || ctx->err) {
73 const char *errstr = "out of memory";
76 log_err("failed to connect to redis server: %s", errstr);
79 if(redisSetTimeout(ctx, moddata->timeout) != REDIS_OK) {
80 log_err("failed to set redis timeout");
92 redis_init(struct module_env* env, struct cachedb_env* cachedb_env)
95 struct redis_moddata* moddata = NULL;
97 verbose(VERB_ALGO, "redis_init");
99 moddata = calloc(1, sizeof(struct redis_moddata));
101 log_err("out of memory");
104 moddata->numctxs = env->cfg->num_threads;
105 moddata->ctxs = calloc(env->cfg->num_threads, sizeof(redisContext*));
107 log_err("out of memory");
111 /* note: server_host is a shallow reference to configured string.
112 * we don't have to free it in this module. */
113 moddata->server_host = env->cfg->redis_server_host;
114 moddata->server_port = env->cfg->redis_server_port;
115 moddata->timeout.tv_sec = env->cfg->redis_timeout / 1000;
116 moddata->timeout.tv_usec = (env->cfg->redis_timeout % 1000) * 1000;
117 for(i = 0; i < moddata->numctxs; i++)
118 moddata->ctxs[i] = redis_connect(moddata);
119 cachedb_env->backend_data = moddata;
120 if(env->cfg->redis_expire_records) {
121 redisReply* rep = NULL;
122 int redis_reply_type = 0;
123 /** check if setex command is supported */
124 rep = redis_command(env, cachedb_env,
125 "SETEX __UNBOUND_REDIS_CHECK__ 1 none", NULL, 0);
127 /** init failed, no response from redis server*/
128 log_err("redis_init: failed to init redis, the "
129 "redis-expire-records option requires the SETEX command "
133 redis_reply_type = rep->type;
134 freeReplyObject(rep);
135 switch(redis_reply_type) {
136 case REDIS_REPLY_STATUS:
139 /** init failed, setex command not supported */
140 log_err("redis_init: failed to init redis, the "
141 "redis-expire-records option requires the SETEX command "
151 redis_deinit(struct module_env* env, struct cachedb_env* cachedb_env)
153 struct redis_moddata* moddata = (struct redis_moddata*)
154 cachedb_env->backend_data;
157 verbose(VERB_ALGO, "redis_deinit");
163 for(i = 0; i < moddata->numctxs; i++) {
165 redisFree(moddata->ctxs[i]);
173 * Send a redis command and get a reply. Unified so that it can be used for
174 * both SET and GET. If 'data' is non-NULL the command is supposed to be
175 * SET and GET otherwise, but the implementation of this function is agnostic
176 * about the semantics (except for logging): 'command', 'data', and 'data_len'
177 * are opaquely passed to redisCommand().
178 * This function first checks whether a connection with a redis server has
179 * been established; if not it tries to set up a new one.
180 * It returns redisReply returned from redisCommand() or NULL if some low
181 * level error happens. The caller is responsible to check the return value,
182 * if it's non-NULL, it has to free it with freeReplyObject().
185 redis_command(struct module_env* env, struct cachedb_env* cachedb_env,
186 const char* command, const uint8_t* data, size_t data_len)
190 struct redis_moddata* d = (struct redis_moddata*)
191 cachedb_env->backend_data;
193 /* We assume env->alloc->thread_num is a unique ID for each thread
194 * in [0, num-of-threads). We could treat it as an error condition
195 * if the assumption didn't hold, but it seems to be a fundamental
196 * assumption throughout the unbound architecture, so we simply assert
198 log_assert(env->alloc->thread_num < d->numctxs);
199 ctx = d->ctxs[env->alloc->thread_num];
201 /* If we've not established a connection to the server or we've closed
202 * it on a failure, try to re-establish a new one. Failures will be
203 * logged in redis_connect(). */
205 ctx = redis_connect(d);
206 d->ctxs[env->alloc->thread_num] = ctx;
211 /* Send the command and get a reply, synchronously. */
212 rep = (redisReply*)redisCommand(ctx, command, data, data_len);
214 /* Once an error as a NULL-reply is returned the context cannot
215 * be reused and we'll need to set up a new connection. */
216 log_err("redis_command: failed to receive a reply, "
217 "closing connection: %s", ctx->errstr);
219 d->ctxs[env->alloc->thread_num] = NULL;
223 /* Check error in reply to unify logging in that case.
224 * The caller may perform context-dependent checks and logging. */
225 if(rep->type == REDIS_REPLY_ERROR)
226 log_err("redis: %s resulted in an error: %s",
227 data ? "set" : "get", rep->str);
233 redis_lookup(struct module_env* env, struct cachedb_env* cachedb_env,
234 char* key, struct sldns_buffer* result_buffer)
237 char cmdbuf[4+(CACHEDB_HASHSIZE/8)*2+1]; /* "GET " + key */
241 verbose(VERB_ALGO, "redis_lookup of %s", key);
243 n = snprintf(cmdbuf, sizeof(cmdbuf), "GET %s", key);
244 if(n < 0 || n >= (int)sizeof(cmdbuf)) {
245 log_err("redis_lookup: unexpected failure to build command");
249 rep = redis_command(env, cachedb_env, cmdbuf, NULL, 0);
253 case REDIS_REPLY_NIL:
254 verbose(VERB_ALGO, "redis_lookup: no data cached");
256 case REDIS_REPLY_STRING:
257 verbose(VERB_ALGO, "redis_lookup found %d bytes",
259 if((size_t)rep->len > sldns_buffer_capacity(result_buffer)) {
260 log_err("redis_lookup: replied data too long: %lu",
264 sldns_buffer_clear(result_buffer);
265 sldns_buffer_write(result_buffer, rep->str, rep->len);
266 sldns_buffer_flip(result_buffer);
269 case REDIS_REPLY_ERROR:
270 break; /* already logged */
272 log_err("redis_lookup: unexpected type of reply for (%d)",
276 freeReplyObject(rep);
281 redis_store(struct module_env* env, struct cachedb_env* cachedb_env,
282 char* key, uint8_t* data, size_t data_len, time_t ttl)
286 int set_ttl = (env->cfg->redis_expire_records &&
287 (!env->cfg->serve_expired || env->cfg->serve_expired_ttl > 0));
288 /* Supported commands:
289 * - "SET " + key + " %b"
290 * - "SETEX " + key + " " + ttl + " %b"
292 char cmdbuf[6+(CACHEDB_HASHSIZE/8)*2+11+3+1];
295 verbose(VERB_ALGO, "redis_store %s (%d bytes)", key, (int)data_len);
296 /* build command to set to a binary safe string */
297 n = snprintf(cmdbuf, sizeof(cmdbuf), "SET %s %%b", key);
299 /* add expired ttl time to redis ttl to avoid premature eviction of key */
300 ttl += env->cfg->serve_expired_ttl;
301 verbose(VERB_ALGO, "redis_store %s (%d bytes) with ttl %u",
302 key, (int)data_len, (uint32_t)ttl);
303 /* build command to set to a binary safe string */
304 n = snprintf(cmdbuf, sizeof(cmdbuf), "SETEX %s %u %%b", key,
309 if(n < 0 || n >= (int)sizeof(cmdbuf)) {
310 log_err("redis_store: unexpected failure to build command");
314 rep = redis_command(env, cachedb_env, cmdbuf, data, data_len);
316 verbose(VERB_ALGO, "redis_store set completed");
317 if(rep->type != REDIS_REPLY_STATUS &&
318 rep->type != REDIS_REPLY_ERROR) {
319 log_err("redis_store: unexpected type of reply (%d)",
322 freeReplyObject(rep);
326 struct cachedb_backend redis_backend = { "redis",
327 redis_init, redis_deinit, redis_lookup, redis_store
329 #endif /* USE_REDIS */
330 #endif /* USE_CACHEDB */