src/scripting.c

   1 #include "redis.h"
   2 #include "sha1.h"
   3 #include "rand.h"
   4
   5 #include <lua.h>
   6 #include <lauxlib.h>
   7 #include <lualib.h>
   8 #include <ctype.h>
   9 #include <math.h>
  10
  11 char *redisProtocolToLuaType_Int(lua_State *lua, char *reply);
  12 char *redisProtocolToLuaType_Bulk(lua_State *lua, char *reply);
  13 char *redisProtocolToLuaType_Status(lua_State *lua, char *reply);
  14 char *redisProtocolToLuaType_Error(lua_State *lua, char *reply);
  15 char *redisProtocolToLuaType_MultiBulk(lua_State *lua, char *reply);
  16 int redis_math_random (lua_State *L);
  17 int redis_math_randomseed (lua_State *L);
  18
  19 /* Take a Redis reply in the Redis protocol format and convert it into a
  20  * Lua type. Thanks to this function, and the introduction of not connected
  21  * clients, it is trvial to implement the redis() lua function.
  22  *
  23  * Basically we take the arguments, execute the Redis command in the context
  24  * of a non connected client, then take the generated reply and convert it
  25  * into a suitable Lua type. With this trick the scripting feature does not
  26  * need the introduction of a full Redis internals API. Basically the script
  27  * is like a normal client that bypasses all the slow I/O paths.
  28  *
  29  * Note: in this function we do not do any sanity check as the reply is
  30  * generated by Redis directly. This allows use to go faster.
  31  * The reply string can be altered during the parsing as it is discared
  32  * after the conversion is completed.
  33  *
  34  * Errors are returned as a table with a single 'err' field set to the
  35  * error string.
  36  */
  37
  38 char *redisProtocolToLuaType(lua_State *lua, char* reply) {
  39     char *p = reply;
  40
  41     switch(*p) {
  42     case ':':
  43         p = redisProtocolToLuaType_Int(lua,reply);
  44         break;
  45     case '$':
  46         p = redisProtocolToLuaType_Bulk(lua,reply);
  47         break;
  48     case '+':
  49         p = redisProtocolToLuaType_Status(lua,reply);
  50         break;
  51     case '-':
  52         p = redisProtocolToLuaType_Error(lua,reply);
  53         break;
  54     case '*':
  55         p = redisProtocolToLuaType_MultiBulk(lua,reply);
  56         break;
  57     }
  58     return p;
  59 }
  60
  61 char *redisProtocolToLuaType_Int(lua_State *lua, char *reply) {
  62     char *p = strchr(reply+1,'\r');
  63     long long value;
  64
  65     string2ll(reply+1,p-reply-1,&value);
  66     lua_pushnumber(lua,(lua_Number)value);
  67     return p+2;
  68 }
  69
  70 char *redisProtocolToLuaType_Bulk(lua_State *lua, char *reply) {
  71     char *p = strchr(reply+1,'\r');
  72     long long bulklen;
  73
  74     string2ll(reply+1,p-reply-1,&bulklen);
  75     if (bulklen == -1) {
  76         lua_pushboolean(lua,0);
  77         return p+2;
  78     } else {
  79         lua_pushlstring(lua,p+2,bulklen);
  80         return p+2+bulklen+2;
  81     }
  82 }
  83
  84 char *redisProtocolToLuaType_Status(lua_State *lua, char *reply) {
  85     char *p = strchr(reply+1,'\r');
  86
  87     lua_newtable(lua);
  88     lua_pushstring(lua,"ok");
  89     lua_pushlstring(lua,reply+1,p-reply-1);
  90     lua_settable(lua,-3);
  91     return p+2;
  92 }
  93
  94 char *redisProtocolToLuaType_Error(lua_State *lua, char *reply) {
  95     char *p = strchr(reply+1,'\r');
  96
  97     lua_newtable(lua);
  98     lua_pushstring(lua,"err");
  99     lua_pushlstring(lua,reply+1,p-reply-1);
 100     lua_settable(lua,-3);
 101     return p+2;
 102 }
 103
 104 char *redisProtocolToLuaType_MultiBulk(lua_State *lua, char *reply) {
 105     char *p = strchr(reply+1,'\r');
 106     long long mbulklen;
 107     int j = 0;
 108
 109     string2ll(reply+1,p-reply-1,&mbulklen);
 110     p += 2;
 111     if (mbulklen == -1) {
 112         lua_pushboolean(lua,0);
 113         return p;
 114     }
 115     lua_newtable(lua);
 116     for (j = 0; j < mbulklen; j++) {
 117         lua_pushnumber(lua,j+1);
 118         p = redisProtocolToLuaType(lua,p);
 119         lua_settable(lua,-3);
 120     }
 121     return p;
 122 }
 123
 124 void luaPushError(lua_State *lua, char *error) {
 125     lua_newtable(lua);
 126     lua_pushstring(lua,"err");
 127     lua_pushstring(lua, error);
 128     lua_settable(lua,-3);
 129 }
 130
 131 int luaRedisCommand(lua_State *lua) {
 132     int j, argc = lua_gettop(lua);
 133     struct redisCommand *cmd;
 134     robj **argv;
 135     redisClient *c = server.lua_client;
 136     sds reply;
 137
 138     /* Build the arguments vector */
 139     argv = zmalloc(sizeof(robj*)*argc);
 140     for (j = 0; j < argc; j++) {
 141         if (!lua_isstring(lua,j+1)) break;
 142         argv[j] = createStringObject((char*)lua_tostring(lua,j+1),
 143                                      lua_strlen(lua,j+1));
 144     }
 145
 146     /* Check if one of the arguments passed by the Lua script
 147      * is not a string or an integer (lua_isstring() return true for
 148      * integers as well). */
 149     if (j != argc) {
 150         j--;
 151         while (j >= 0) {
 152             decrRefCount(argv[j]);
 153             j--;
 154         }
 155         zfree(argv);
 156         luaPushError(lua,
 157             "Lua redis() command arguments must be strings or integers");
 158         return 1;
 159     }
 160
 161     /* Setup our fake client for command execution */
 162     c->argv = argv;
 163     c->argc = argc;
 164
 165     /* Command lookup */
 166     cmd = lookupCommand(argv[0]->ptr);
 167     if (!cmd || ((cmd->arity > 0 && cmd->arity != argc) ||
 168                    (argc < -cmd->arity)))
 169     {
 170         if (cmd)
 171             luaPushError(lua,
 172                 "Wrong number of args calling Redis command From Lua script");
 173         else
 174             luaPushError(lua,"Unknown Redis command called from Lua script");
 175         goto cleanup;
 176     }
 177
 178     if (cmd->flags & REDIS_CMD_NOSCRIPT) {
 179         luaPushError(lua, "This Redis command is not allowed from scripts");
 180         goto cleanup;
 181     }
 182
 183     if (cmd->flags & REDIS_CMD_WRITE && server.lua_random_dirty) {
 184         luaPushError(lua,
 185             "Write commands not allowed after non deterministic commands");
 186         goto cleanup;
 187     }
 188
 189     if (cmd->flags & REDIS_CMD_RANDOM) server.lua_random_dirty = 1;
 190
 191     /* Run the command */
 192     cmd->proc(c);
 193
 194     /* Convert the result of the Redis command into a suitable Lua type.
 195      * The first thing we need is to create a single string from the client
 196      * output buffers. */
 197     reply = sdsempty();
 198     if (c->bufpos) {
 199         reply = sdscatlen(reply,c->buf,c->bufpos);
 200         c->bufpos = 0;
 201     }
 202     while(listLength(c->reply)) {
 203         robj *o = listNodeValue(listFirst(c->reply));
 204
 205         reply = sdscatlen(reply,o->ptr,sdslen(o->ptr));
 206         listDelNode(c->reply,listFirst(c->reply));
 207     }
 208     redisProtocolToLuaType(lua,reply);
 209     sdsfree(reply);
 210
 211 cleanup:
 212     /* Clean up. Command code may have changed argv/argc so we use the
 213      * argv/argc of the client instead of the local variables. */
 214     for (j = 0; j < c->argc; j++)
 215         decrRefCount(c->argv[j]);
 216     zfree(c->argv);
 217
 218     return 1;
 219 }
 220
 221 int luaLogCommand(lua_State *lua) {
 222     int j, argc = lua_gettop(lua);
 223     int level;
 224     sds log;
 225
 226     if (argc < 2) {
 227         luaPushError(lua, "redis.log() requires two arguments or more.");
 228         return 1;
 229     } else if (!lua_isnumber(lua,-argc)) {
 230         luaPushError(lua, "First argument must be a number (log level).");
 231         return 1;
 232     }
 233     level = lua_tonumber(lua,-argc);
 234     if (level < REDIS_DEBUG || level > REDIS_WARNING) {
 235         luaPushError(lua, "Invalid debug level.");
 236         return 1;
 237     }
 238
 239     /* Glue together all the arguments */
 240     log = sdsempty();
 241     for (j = 1; j < argc; j++) {
 242         size_t len;
 243         char *s;
 244
 245         s = (char*)lua_tolstring(lua,(-argc)+j,&len);
 246         if (s) {
 247             if (j != 1) log = sdscatlen(log," ",1);
 248             log = sdscatlen(log,s,len);
 249         }
 250     }
 251     redisLogRaw(level,log);
 252     sdsfree(log);
 253     return 0;
 254 }
 255
 256 void luaMaskCountHook(lua_State *lua, lua_Debug *ar) {
 257     long long elapsed;
 258     REDIS_NOTUSED(ar);
 259
 260     elapsed = (ustime()/1000) - server.lua_time_start;
 261     if (elapsed >= server.lua_time_limit) {
 262         redisLog(REDIS_NOTICE,"Lua script aborted for max execution time after %lld milliseconds of running time.",elapsed);
 263         lua_pushstring(lua,"Script aborted for max execution time.");
 264         lua_error(lua);
 265     }
 266 }
 267
 268 void scriptingInit(void) {
 269     lua_State *lua = lua_open();
 270     luaL_openlibs(lua);
 271
 272     /* Initialize a dictionary we use to map SHAs to scripts.
 273      * This is useful for replication, as we need to replicate EVALSHA
 274      * as EVAL, so we need to remember the associated script. */
 275     server.lua_scripts = dictCreate(&dbDictType,NULL);
 276
 277     /* Register the redis commands table and fields */
 278     lua_newtable(lua);
 279
 280     /* redis.call */
 281     lua_pushstring(lua,"call");
 282     lua_pushcfunction(lua,luaRedisCommand);
 283     lua_settable(lua,-3);
 284
 285     /* redis.log and log levels. */
 286     lua_pushstring(lua,"log");
 287     lua_pushcfunction(lua,luaLogCommand);
 288     lua_settable(lua,-3);
 289
 290     lua_pushstring(lua,"LOG_DEBUG");
 291     lua_pushnumber(lua,REDIS_DEBUG);
 292     lua_settable(lua,-3);
 293
 294     lua_pushstring(lua,"LOG_VERBOSE");
 295     lua_pushnumber(lua,REDIS_VERBOSE);
 296     lua_settable(lua,-3);
 297
 298     lua_pushstring(lua,"LOG_NOTICE");
 299     lua_pushnumber(lua,REDIS_NOTICE);
 300     lua_settable(lua,-3);
 301
 302     lua_pushstring(lua,"LOG_WARNING");
 303     lua_pushnumber(lua,REDIS_WARNING);
 304     lua_settable(lua,-3);
 305
 306     /* Finally set the table as 'redis' global var. */
 307     lua_setglobal(lua,"redis");
 308
 309     /* Replace math.random and math.randomseed with our implementations. */
 310     lua_getglobal(lua,"math");
 311
 312     lua_pushstring(lua,"random");
 313     lua_pushcfunction(lua,redis_math_random);
 314     lua_settable(lua,-3);
 315
 316     lua_pushstring(lua,"randomseed");
 317     lua_pushcfunction(lua,redis_math_randomseed);
 318     lua_settable(lua,-3);
 319
 320     lua_setglobal(lua,"math");
 321
 322     /* Create the (non connected) client that we use to execute Redis commands
 323      * inside the Lua interpreter */
 324     server.lua_client = createClient(-1);
 325     server.lua_client->flags |= REDIS_LUA_CLIENT;
 326
 327     server.lua = lua;
 328 }
 329
 330 /* Hash the scripit into a SHA1 digest. We use this as Lua function name.
 331  * Digest should point to a 41 bytes buffer: 40 for SHA1 converted into an
 332  * hexadecimal number, plus 1 byte for null term. */
 333 void hashScript(char *digest, char *script, size_t len) {
 334     SHA1_CTX ctx;
 335     unsigned char hash[20];
 336     char *cset = "0123456789abcdef";
 337     int j;
 338
 339     SHA1Init(&ctx);
 340     SHA1Update(&ctx,(unsigned char*)script,len);
 341     SHA1Final(hash,&ctx);
 342
 343     for (j = 0; j < 20; j++) {
 344         digest[j*2] = cset[((hash[j]&0xF0)>>4)];
 345         digest[j*2+1] = cset[(hash[j]&0xF)];
 346     }
 347     digest[40] = '\0';
 348 }
 349
 350 void luaReplyToRedisReply(redisClient *c, lua_State *lua) {
 351     int t = lua_type(lua,-1);
 352
 353     switch(t) {
 354     case LUA_TSTRING:
 355         addReplyBulkCBuffer(c,(char*)lua_tostring(lua,-1),lua_strlen(lua,-1));
 356         break;
 357     case LUA_TBOOLEAN:
 358         addReply(c,lua_toboolean(lua,-1) ? shared.cone : shared.nullbulk);
 359         break;
 360     case LUA_TNUMBER:
 361         addReplyLongLong(c,(long long)lua_tonumber(lua,-1));
 362         break;
 363     case LUA_TTABLE:
 364         /* We need to check if it is an array, an error, or a status reply.
 365          * Error are returned as a single element table with 'err' field.
 366          * Status replies are returned as single elment table with 'ok' field */
 367         lua_pushstring(lua,"err");
 368         lua_gettable(lua,-2);
 369         t = lua_type(lua,-1);
 370         if (t == LUA_TSTRING) {
 371             sds err = sdsnew(lua_tostring(lua,-1));
 372             sdsmapchars(err,"\r\n","  ",2);
 373             addReplySds(c,sdscatprintf(sdsempty(),"-%s\r\n",err));
 374             sdsfree(err);
 375             lua_pop(lua,2);
 376             return;
 377         }
 378
 379         lua_pop(lua,1);
 380         lua_pushstring(lua,"ok");
 381         lua_gettable(lua,-2);
 382         t = lua_type(lua,-1);
 383         if (t == LUA_TSTRING) {
 384             sds ok = sdsnew(lua_tostring(lua,-1));
 385             sdsmapchars(ok,"\r\n","  ",2);
 386             addReplySds(c,sdscatprintf(sdsempty(),"+%s\r\n",ok));
 387             sdsfree(ok);
 388             lua_pop(lua,1);
 389         } else {
 390             void *replylen = addDeferredMultiBulkLength(c);
 391             int j = 1, mbulklen = 0;
 392
 393             lua_pop(lua,1); /* Discard the 'ok' field value we popped */
 394             while(1) {
 395                 lua_pushnumber(lua,j++);
 396                 lua_gettable(lua,-2);
 397                 t = lua_type(lua,-1);
 398                 if (t == LUA_TNIL) {
 399                     lua_pop(lua,1);
 400                     break;
 401                 }
 402                 luaReplyToRedisReply(c, lua);
 403                 mbulklen++;
 404             }
 405             setDeferredMultiBulkLength(c,replylen,mbulklen);
 406         }
 407         break;
 408     default:
 409         addReply(c,shared.nullbulk);
 410     }
 411     lua_pop(lua,1);
 412 }
 413
 414 /* Set an array of Redis String Objects as a Lua array (table) stored into a
 415  * global variable. */
 416 void luaSetGlobalArray(lua_State *lua, char *var, robj **elev, int elec) {
 417     int j;
 418
 419     lua_newtable(lua);
 420     for (j = 0; j < elec; j++) {
 421         lua_pushlstring(lua,(char*)elev[j]->ptr,sdslen(elev[j]->ptr));
 422         lua_rawseti(lua,-2,j+1);
 423     }
 424     lua_setglobal(lua,var);
 425 }
 426
 427 void evalGenericCommand(redisClient *c, int evalsha) {
 428     lua_State *lua = server.lua;
 429     char funcname[43];
 430     long long numkeys;
 431
 432     /* We want the same PRNG sequence at every call so that our PRNG is
 433      * not affected by external state. */
 434     redisSrand48(0);
 435
 436     /* We set this flag to zero to remember that so far no random command
 437      * was called. This way we can allow the user to call commands like
 438      * SRANDMEMBER or RANDOMKEY from Lua scripts as far as no write command
 439      * is called (otherwise the replication and AOF would end with non
 440      * deterministic sequences).
 441      *
 442      * Thanks to this flag we'll raise an error every time a write command
 443      * is called after a random command was used. */
 444     server.lua_random_dirty = 0;
 445
 446     /* Get the number of arguments that are keys */
 447     if (getLongLongFromObjectOrReply(c,c->argv[2],&numkeys,NULL) != REDIS_OK)
 448         return;
 449     if (numkeys > (c->argc - 3)) {
 450         addReplyError(c,"Number of keys can't be greater than number of args");
 451         return;
 452     }
 453
 454     /* We obtain the script SHA1, then check if this function is already
 455      * defined into the Lua state */
 456     funcname[0] = 'f';
 457     funcname[1] = '_';
 458     if (!evalsha) {
 459         /* Hash the code if this is an EVAL call */
 460         hashScript(funcname+2,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
 461     } else {
 462         /* We already have the SHA if it is a EVALSHA */
 463         int j;
 464         char *sha = c->argv[1]->ptr;
 465
 466         for (j = 0; j < 40; j++)
 467             funcname[j+2] = tolower(sha[j]);
 468         funcname[42] = '\0';
 469     }
 470
 471     lua_getglobal(lua, funcname);
 472     if (lua_isnil(lua,1)) {
 473         sds funcdef;
 474
 475         /* Function not defined... let's define it if we have the
 476          * body of the funciton. If this is an EVALSHA call we can just
 477          * return an error. */
 478         if (evalsha) {
 479             addReply(c, shared.noscripterr);
 480             lua_pop(lua,1); /* remove the nil from the stack */
 481             return;
 482         }
 483         funcdef = sdsempty();
 484
 485         lua_pop(lua,1); /* remove the nil from the stack */
 486         funcdef = sdscat(funcdef,"function ");
 487         funcdef = sdscatlen(funcdef,funcname,42);
 488         funcdef = sdscatlen(funcdef," ()\n",4);
 489         funcdef = sdscatlen(funcdef,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
 490         funcdef = sdscatlen(funcdef,"\nend\n",5);
 491         /* printf("Defining:\n%s\n",funcdef); */
 492
 493         if (luaL_loadbuffer(lua,funcdef,sdslen(funcdef),"func definition")) {
 494             addReplyErrorFormat(c,"Error compiling script (new function): %s\n",
 495                 lua_tostring(lua,-1));
 496             lua_pop(lua,1);
 497             sdsfree(funcdef);
 498             return;
 499         }
 500         sdsfree(funcdef);
 501         if (lua_pcall(lua,0,0,0)) {
 502             addReplyErrorFormat(c,"Error running script (new function): %s\n",
 503                 lua_tostring(lua,-1));
 504             lua_pop(lua,1);
 505             return;
 506         }
 507         lua_getglobal(lua, funcname);
 508
 509         /* We also save a SHA1 -> Original script map in a dictionary
 510          * so that we can replicate / write in the AOF all the
 511          * EVALSHA commands as EVAL using the original script. */
 512         {
 513             int retval = dictAdd(server.lua_scripts,
 514                                  sdsnewlen(funcname+2,40),c->argv[1]);
 515             redisAssert(retval == DICT_OK);
 516             incrRefCount(c->argv[1]);
 517         }
 518     }
 519
 520     /* Populate the argv and keys table accordingly to the arguments that
 521      * EVAL received. */
 522     luaSetGlobalArray(lua,"KEYS",c->argv+3,numkeys);
 523     luaSetGlobalArray(lua,"ARGV",c->argv+3+numkeys,c->argc-3-numkeys);
 524
 525     /* Select the right DB in the context of the Lua client */
 526     selectDb(server.lua_client,c->db->id);
 527
 528     /* Set an hook in order to be able to stop the script execution if it
 529      * is running for too much time.
 530      * We set the hook only if the time limit is enabled as the hook will
 531      * make the Lua script execution slower. */
 532     if (server.lua_time_limit > 0) {
 533         lua_sethook(lua,luaMaskCountHook,LUA_MASKCOUNT,100000);
 534         server.lua_time_start = ustime()/1000;
 535     } else {
 536         lua_sethook(lua,luaMaskCountHook,0,0);
 537     }
 538
 539     /* At this point whatever this script was never seen before or if it was
 540      * already defined, we can call it. We have zero arguments and expect
 541      * a single return value. */
 542     if (lua_pcall(lua,0,1,0)) {
 543         selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
 544         addReplyErrorFormat(c,"Error running script (call to %s): %s\n",
 545             funcname, lua_tostring(lua,-1));
 546         lua_pop(lua,1);
 547         lua_gc(lua,LUA_GCCOLLECT,0);
 548         return;
 549     }
 550     selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
 551     luaReplyToRedisReply(c,lua);
 552     lua_gc(lua,LUA_GCSTEP,1);
 553
 554     /* If we have slaves attached we want to replicate this command as
 555      * EVAL instead of EVALSHA. We do this also in the AOF as currently there
 556      * is no easy way to propagate a command in a different way in the AOF
 557      * and in the replication link.
 558      *
 559      * IMPROVEMENT POSSIBLE:
 560      * 1) Replicate this command as EVALSHA in the AOF.
 561      * 2) Remember what slave already received a given script, and replicate
 562      *    the EVALSHA against this slaves when possible.
 563      */
 564     if (evalsha) {
 565         robj *script = dictFetchValue(server.lua_scripts,c->argv[1]->ptr);
 566
 567         redisAssert(script != NULL);
 568         rewriteClientCommandArgument(c,0,
 569             resetRefCount(createStringObject("EVAL",4)));
 570         rewriteClientCommandArgument(c,1,script);
 571     }
 572 }
 573
 574 void evalCommand(redisClient *c) {
 575     evalGenericCommand(c,0);
 576 }
 577
 578 void evalShaCommand(redisClient *c) {
 579     if (sdslen(c->argv[1]->ptr) != 40) {
 580         /* We know that a match is not possible if the provided SHA is
 581          * not the right length. So we return an error ASAP, this way
 582          * evalGenericCommand() can be implemented without string length
 583          * sanity check */
 584         addReply(c, shared.noscripterr);
 585         return;
 586     }
 587     evalGenericCommand(c,1);
 588 }
 589
 590 /* We replace math.random() with our implementation that is not affected
 591  * by specific libc random() implementations and will output the same sequence
 592  * (for the same seed) in every arch. */
 593
 594 /* The following implementation is the one shipped with Lua itself but with
 595  * rand() replaced by redisLrand48(). */
 596 int redis_math_random (lua_State *L) {
 597   /* the `%' avoids the (rare) case of r==1, and is needed also because on
 598      some systems (SunOS!) `rand()' may return a value larger than RAND_MAX */
 599   lua_Number r = (lua_Number)(redisLrand48()%REDIS_LRAND48_MAX) /
 600                                 (lua_Number)REDIS_LRAND48_MAX;
 601   switch (lua_gettop(L)) {  /* check number of arguments */
 602     case 0: {  /* no arguments */
 603       lua_pushnumber(L, r);  /* Number between 0 and 1 */
 604       break;
 605     }
 606     case 1: {  /* only upper limit */
 607       int u = luaL_checkint(L, 1);
 608       luaL_argcheck(L, 1<=u, 1, "interval is empty");
 609       lua_pushnumber(L, floor(r*u)+1);  /* int between 1 and `u' */
 610       break;
 611     }
 612     case 2: {  /* lower and upper limits */
 613       int l = luaL_checkint(L, 1);
 614       int u = luaL_checkint(L, 2);
 615       luaL_argcheck(L, l<=u, 2, "interval is empty");
 616       lua_pushnumber(L, floor(r*(u-l+1))+l);  /* int between `l' and `u' */
 617       break;
 618     }
 619     default: return luaL_error(L, "wrong number of arguments");
 620   }
 621   return 1;
 622 }
 623
 624 int redis_math_randomseed (lua_State *L) {
 625   redisSrand48(luaL_checkint(L, 1));
 626   return 0;
 627 }