src/scripting.c

   1 #include "redis.h"
   2 #include "sha1.h"
   3
   4 #include <lua.h>
   5 #include <lauxlib.h>
   6 #include <lualib.h>
   7
   8 char *redisProtocolToLuaType_Int(lua_State *lua, char *reply);
   9 char *redisProtocolToLuaType_Bulk(lua_State *lua, char *reply);
  10 char *redisProtocolToLuaType_Status(lua_State *lua, char *reply);
  11 char *redisProtocolToLuaType_Error(lua_State *lua, char *reply);
  12 char *redisProtocolToLuaType_MultiBulk(lua_State *lua, char *reply);
  13
  14 /* Take a Redis reply in the Redis protocol format and convert it into a
  15  * Lua type. Thanks to this function, and the introduction of not connected
  16  * clients, it is trvial to implement the redis() lua function.
  17  *
  18  * Basically we take the arguments, execute the Redis command in the context
  19  * of a non connected client, then take the generated reply and convert it
  20  * into a suitable Lua type. With this trick the scripting feature does not
  21  * need the introduction of a full Redis internals API. Basically the script
  22  * is like a normal client that bypasses all the slow I/O paths.
  23  *
  24  * Note: in this function we do not do any sanity check as the reply is
  25  * generated by Redis directly. This allows use to go faster.
  26  * The reply string can be altered during the parsing as it is discared
  27  * after the conversion is completed.
  28  *
  29  * Errors are returned as a table with a single 'err' field set to the
  30  * error string.
  31  */
  32
  33 char *redisProtocolToLuaType(lua_State *lua, char* reply) {
  34     char *p = reply;
  35
  36     switch(*p) {
  37     case ':':
  38         p = redisProtocolToLuaType_Int(lua,reply);
  39         break;
  40     case '$':
  41         p = redisProtocolToLuaType_Bulk(lua,reply);
  42         break;
  43     case '+':
  44         p = redisProtocolToLuaType_Status(lua,reply);
  45         break;
  46     case '-':
  47         p = redisProtocolToLuaType_Error(lua,reply);
  48         break;
  49     case '*':
  50         p = redisProtocolToLuaType_MultiBulk(lua,reply);
  51         break;
  52     }
  53     return p;
  54 }
  55
  56 char *redisProtocolToLuaType_Int(lua_State *lua, char *reply) {
  57     char *p = strchr(reply+1,'\r');
  58     long long value;
  59
  60     string2ll(reply+1,p-reply-1,&value);
  61     lua_pushnumber(lua,(lua_Number)value);
  62     return p+2;
  63 }
  64
  65 char *redisProtocolToLuaType_Bulk(lua_State *lua, char *reply) {
  66     char *p = strchr(reply+1,'\r');
  67     long long bulklen;
  68
  69     string2ll(reply+1,p-reply-1,&bulklen);
  70     if (bulklen == -1) {
  71         lua_pushnil(lua);
  72         return p+2;
  73     } else {
  74         lua_pushlstring(lua,p+2,bulklen);
  75         return p+2+bulklen+2;
  76     }
  77 }
  78
  79 char *redisProtocolToLuaType_Status(lua_State *lua, char *reply) {
  80     char *p = strchr(reply+1,'\r');
  81
  82     lua_newtable(lua);
  83     lua_pushstring(lua,"ok");
  84     lua_pushlstring(lua,reply+1,p-reply-1);
  85     lua_settable(lua,-3);
  86     return p+2;
  87 }
  88
  89 char *redisProtocolToLuaType_Error(lua_State *lua, char *reply) {
  90     char *p = strchr(reply+1,'\r');
  91
  92     lua_newtable(lua);
  93     lua_pushstring(lua,"err");
  94     lua_pushlstring(lua,reply+1,p-reply-1);
  95     lua_settable(lua,-3);
  96     return p+2;
  97 }
  98
  99 char *redisProtocolToLuaType_MultiBulk(lua_State *lua, char *reply) {
 100     char *p = strchr(reply+1,'\r');
 101     long long mbulklen;
 102     int j = 0;
 103
 104     string2ll(reply+1,p-reply-1,&mbulklen);
 105     p += 2;
 106     if (mbulklen == -1) {
 107         lua_pushnil(lua);
 108         return p;
 109     }
 110     lua_newtable(lua);
 111     for (j = 0; j < mbulklen; j++) {
 112         lua_pushnumber(lua,j+1);
 113         p = redisProtocolToLuaType(lua,p);
 114         lua_settable(lua,-3);
 115     }
 116     return p;
 117 }
 118
 119 void luaPushError(lua_State *lua, char *error) {
 120     lua_newtable(lua);
 121     lua_pushstring(lua,"err");
 122     lua_pushstring(lua, error);
 123     lua_settable(lua,-3);
 124 }
 125
 126 int luaRedisCommand(lua_State *lua) {
 127     int j, argc = lua_gettop(lua);
 128     struct redisCommand *cmd;
 129     robj **argv;
 130     redisClient *c = server.lua_client;
 131     sds reply;
 132
 133     /* Build the arguments vector */
 134     argv = zmalloc(sizeof(robj*)*argc);
 135     for (j = 0; j < argc; j++) {
 136         if (!lua_isstring(lua,j+1)) break;
 137         argv[j] = createStringObject((char*)lua_tostring(lua,j+1),
 138                                      lua_strlen(lua,j+1));
 139     }
 140
 141     /* Check if one of the arguments passed by the Lua script
 142      * is not a string or an integer (lua_isstring() return true for
 143      * integers as well). */
 144     if (j != argc) {
 145         j--;
 146         while (j >= 0) {
 147             decrRefCount(argv[j]);
 148             j--;
 149         }
 150         zfree(argv);
 151         luaPushError(lua,
 152             "Lua redis() command arguments must be strings or integers");
 153         return 1;
 154     }
 155
 156     /* Command lookup */
 157     cmd = lookupCommand(argv[0]->ptr);
 158     if (!cmd || ((cmd->arity > 0 && cmd->arity != argc) ||
 159                    (argc < -cmd->arity)))
 160     {
 161         for (j = 0; j < argc; j++) decrRefCount(argv[j]);
 162         zfree(argv);
 163         if (cmd)
 164             luaPushError(lua,
 165                 "Wrong number of args calling Redis command From Lua script");
 166         else
 167             luaPushError(lua,"Unknown Redis command called from Lua script");
 168         return 1;
 169     }
 170
 171     /* Run the command in the context of a fake client */
 172     c->argv = argv;
 173     c->argc = argc;
 174     cmd->proc(c);
 175
 176     /* Convert the result of the Redis command into a suitable Lua type.
 177      * The first thing we need is to create a single string from the client
 178      * output buffers. */
 179     reply = sdsempty();
 180     if (c->bufpos) {
 181         reply = sdscatlen(reply,c->buf,c->bufpos);
 182         c->bufpos = 0;
 183     }
 184     while(listLength(c->reply)) {
 185         robj *o = listNodeValue(listFirst(c->reply));
 186
 187         reply = sdscatlen(reply,o->ptr,sdslen(o->ptr));
 188         listDelNode(c->reply,listFirst(c->reply));
 189     }
 190     redisProtocolToLuaType(lua,reply);
 191     sdsfree(reply);
 192
 193     /* Clean up. Command code may have changed argv/argc so we use the
 194      * argv/argc of the client instead of the local variables. */
 195     for (j = 0; j < c->argc; j++)
 196         decrRefCount(c->argv[j]);
 197     zfree(c->argv);
 198
 199     return 1;
 200 }
 201
 202 void scriptingInit(void) {
 203     lua_State *lua = lua_open();
 204     luaL_openlibs(lua);
 205
 206     /* Register the 'r' command */
 207     lua_pushcfunction(lua,luaRedisCommand);
 208     lua_setglobal(lua,"redis");
 209
 210     /* Create the (non connected) client that we use to execute Redis commands
 211      * inside the Lua interpreter */
 212     server.lua_client = createClient(-1);
 213     server.lua_client->flags |= REDIS_LUA_CLIENT;
 214
 215     server.lua = lua;
 216 }
 217
 218 /* Hash the scripit into a SHA1 digest. We use this as Lua function name.
 219  * Digest should point to a 41 bytes buffer: 40 for SHA1 converted into an
 220  * hexadecimal number, plus 1 byte for null term. */
 221 void hashScript(char *digest, char *script, size_t len) {
 222     SHA1_CTX ctx;
 223     unsigned char hash[20];
 224     char *cset = "0123456789abcdef";
 225     int j;
 226
 227     SHA1Init(&ctx);
 228     SHA1Update(&ctx,(unsigned char*)script,len);
 229     SHA1Final(hash,&ctx);
 230
 231     for (j = 0; j < 20; j++) {
 232         digest[j*2] = cset[((hash[j]&0xF0)>>4)];
 233         digest[j*2+1] = cset[(hash[j]&0xF)];
 234     }
 235     digest[40] = '\0';
 236 }
 237
 238 void luaReplyToRedisReply(redisClient *c, lua_State *lua) {
 239     int t = lua_type(lua,1);
 240
 241     switch(t) {
 242     case LUA_TSTRING:
 243         addReplyBulkCBuffer(c,(char*)lua_tostring(lua,1),lua_strlen(lua,1));
 244         break;
 245     case LUA_TBOOLEAN:
 246         addReply(c,lua_toboolean(lua,1) ? shared.cone : shared.czero);
 247         break;
 248     case LUA_TNUMBER:
 249         addReplyLongLong(c,(long long)lua_tonumber(lua,1));
 250         break;
 251     case LUA_TTABLE:
 252         /* We need to check if it is an array, an error, or a status reply.
 253          * Error are returned as a single element table with 'err' field.
 254          * Status replies are returned as single elment table with 'ok' field */
 255         lua_pushstring(lua,"err");
 256         lua_gettable(lua,-2);
 257         t = lua_type(lua,-1);
 258         if (t == LUA_TSTRING) {
 259             addReplySds(c,sdscatprintf(sdsempty(),
 260                     "-%s\r\n",(char*)lua_tostring(lua,-1)));
 261             lua_pop(lua,2);
 262             return;
 263         }
 264
 265         lua_pop(lua,1);
 266         lua_pushstring(lua,"ok");
 267         lua_gettable(lua,-2);
 268         t = lua_type(lua,-1);
 269         if (t == LUA_TSTRING) {
 270             addReplySds(c,sdscatprintf(sdsempty(),
 271                     "+%s\r\n",(char*)lua_tostring(lua,-1)));
 272             lua_pop(lua,1);
 273         } else {
 274             void *replylen = addDeferredMultiBulkLength(c);
 275             int j = 1, mbulklen = 0;
 276
 277             lua_pop(lua,1); /* Discard the 'ok' field value we popped */
 278             while(1) {
 279                 lua_pushnumber(lua,j++);
 280                 lua_gettable(lua,-2);
 281                 t = lua_type(lua,-1);
 282                 if (t == LUA_TNIL) {
 283                     lua_pop(lua,1);
 284                     break;
 285                 } else if (t == LUA_TSTRING) {
 286                     size_t len;
 287                     char *s = (char*) lua_tolstring(lua,-1,&len);
 288
 289                     addReplyBulkCBuffer(c,s,len);
 290                     mbulklen++;
 291                 } else if (t == LUA_TNUMBER) {
 292                     addReplyLongLong(c,(long long)lua_tonumber(lua,-1));
 293                     mbulklen++;
 294                 }
 295                 lua_pop(lua,1);
 296             }
 297             setDeferredMultiBulkLength(c,replylen,mbulklen);
 298         }
 299         break;
 300     default:
 301         addReply(c,shared.nullbulk);
 302     }
 303     lua_pop(lua,1);
 304 }
 305
 306 /* Set an array of Redis String Objects as a Lua array (table) stored into a
 307  * global variable. */
 308 void luaSetGlobalArray(lua_State *lua, char *var, robj **elev, int elec) {
 309     int j;
 310
 311     lua_newtable(lua);
 312     for (j = 0; j < elec; j++) {
 313         lua_pushlstring(lua,(char*)elev[j]->ptr,sdslen(elev[j]->ptr));
 314         lua_rawseti(lua,-2,j+1);
 315     }
 316     lua_setglobal(lua,var);
 317 }
 318
 319 void evalCommand(redisClient *c) {
 320     lua_State *lua = server.lua;
 321     char funcname[43];
 322     long long numkeys;
 323
 324     /* Get the number of arguments that are keys */
 325     if (getLongLongFromObjectOrReply(c,c->argv[2],&numkeys,NULL) != REDIS_OK)
 326         return;
 327     if (numkeys > (c->argc - 3)) {
 328         addReplyError(c,"Number of keys can't be greater than number of args");
 329         return;
 330     }
 331
 332     /* We obtain the script SHA1, then check if this function is already
 333      * defined into the Lua state */
 334     funcname[0] = 'f';
 335     funcname[1] = '_';
 336     hashScript(funcname+2,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
 337     lua_getglobal(lua, funcname);
 338     if (lua_isnil(lua,1)) {
 339         /* Function not defined... let's define it. */
 340         sds funcdef = sdsempty();
 341
 342         lua_pop(lua,1); /* remove the nil from the stack */
 343         funcdef = sdscat(funcdef,"function ");
 344         funcdef = sdscatlen(funcdef,funcname,42);
 345         funcdef = sdscatlen(funcdef," ()\n",4);
 346         funcdef = sdscatlen(funcdef,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
 347         funcdef = sdscatlen(funcdef,"\nend\n",5);
 348         /* printf("Defining:\n%s\n",funcdef); */
 349
 350         if (luaL_loadbuffer(lua,funcdef,sdslen(funcdef),"func definition")) {
 351             addReplyErrorFormat(c,"Error compiling script (new function): %s\n",
 352                 lua_tostring(lua,-1));
 353             lua_pop(lua,1);
 354             sdsfree(funcdef);
 355             return;
 356         }
 357         sdsfree(funcdef);
 358         if (lua_pcall(lua,0,0,0)) {
 359             addReplyErrorFormat(c,"Error running script (new function): %s\n",
 360                 lua_tostring(lua,-1));
 361             lua_pop(lua,1);
 362             return;
 363         }
 364         lua_getglobal(lua, funcname);
 365     }
 366
 367     /* Populate the argv and keys table accordingly to the arguments that
 368      * EVAL received. */
 369     luaSetGlobalArray(lua,"KEYS",c->argv+3,numkeys);
 370     luaSetGlobalArray(lua,"ARGV",c->argv+3+numkeys,c->argc-3-numkeys);
 371
 372     /* Select the right DB in the context of the Lua client */
 373     selectDb(server.lua_client,c->db->id);
 374
 375     /* At this point whatever this script was never seen before or if it was
 376      * already defined, we can call it. We have zero arguments and expect
 377      * a single return value. */
 378     if (lua_pcall(lua,0,1,0)) {
 379         selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
 380         addReplyErrorFormat(c,"Error running script (call to %s): %s\n",
 381             funcname, lua_tostring(lua,-1));
 382         lua_pop(lua,1);
 383         return;
 384     }
 385     selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
 386     luaReplyToRedisReply(c,lua);
 387 }