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_pushlstring(lua,reply+1,p-reply-1);
  83     return p+2;
  84 }
  85
  86 char *redisProtocolToLuaType_Error(lua_State *lua, char *reply) {
  87     char *p = strchr(reply+1,'\r');
  88
  89     lua_newtable(lua);
  90     lua_pushstring(lua,"err");
  91     lua_pushlstring(lua,reply+1,p-reply-1);
  92     lua_settable(lua,-3);
  93     return p+2;
  94 }
  95
  96 char *redisProtocolToLuaType_MultiBulk(lua_State *lua, char *reply) {
  97     char *p = strchr(reply+1,'\r');
  98     long long mbulklen;
  99     int j = 0;
 100
 101     string2ll(reply+1,p-reply-1,&mbulklen);
 102     p += 2;
 103     if (mbulklen == -1) {
 104         lua_pushnil(lua);
 105         return p;
 106     }
 107     lua_newtable(lua);
 108     for (j = 0; j < mbulklen; j++) {
 109         lua_pushnumber(lua,j+1);
 110         p = redisProtocolToLuaType(lua,p);
 111         lua_settable(lua,-3);
 112     }
 113     return p;
 114 }
 115
 116 void luaPushError(lua_State *lua, char *error) {
 117     lua_newtable(lua);
 118     lua_pushstring(lua,"err");
 119     lua_pushstring(lua, error);
 120     lua_settable(lua,-3);
 121 }
 122
 123 int luaRedisCommand(lua_State *lua) {
 124     int j, argc = lua_gettop(lua);
 125     struct redisCommand *cmd;
 126     robj **argv;
 127     redisClient *c = server.lua_client;
 128     sds reply;
 129
 130     /* Build the arguments vector */
 131     argv = zmalloc(sizeof(robj*)*argc);
 132     for (j = 0; j < argc; j++) {
 133         if (!lua_isstring(lua,j+1)) break;
 134         argv[j] = createStringObject((char*)lua_tostring(lua,j+1),
 135                                      lua_strlen(lua,j+1));
 136     }
 137
 138     /* Check if one of the arguments passed by the Lua script
 139      * is not a string or an integer (lua_isstring() return true for
 140      * integers as well). */
 141     if (j != argc) {
 142         j--;
 143         while (j >= 0) {
 144             decrRefCount(argv[j]);
 145             j--;
 146         }
 147         zfree(argv);
 148         luaPushError(lua,
 149             "Lua redis() command arguments must be strings or integers");
 150         return 1;
 151     }
 152
 153     /* Command lookup */
 154     cmd = lookupCommand(argv[0]->ptr);
 155     if (!cmd || ((cmd->arity > 0 && cmd->arity != argc) ||
 156                    (argc < -cmd->arity)))
 157     {
 158         for (j = 0; j < argc; j++) decrRefCount(argv[j]);
 159         zfree(argv);
 160         if (cmd)
 161             luaPushError(lua,
 162                 "Wrong number of args calling Redis command From Lua script");
 163         else
 164             luaPushError(lua,"Unknown Redis command called from Lua script");
 165         return 1;
 166     }
 167
 168     /* Run the command in the context of a fake client */
 169     c->argv = argv;
 170     c->argc = argc;
 171     cmd->proc(c);
 172
 173     /* Convert the result of the Redis command into a suitable Lua type.
 174      * The first thing we need is to create a single string from the client
 175      * output buffers. */
 176     reply = sdsempty();
 177     if (c->bufpos) {
 178         reply = sdscatlen(reply,c->buf,c->bufpos);
 179         c->bufpos = 0;
 180     }
 181     while(listLength(c->reply)) {
 182         robj *o = listNodeValue(listFirst(c->reply));
 183
 184         sdscatlen(reply,o->ptr,sdslen(o->ptr));
 185         listDelNode(c->reply,listFirst(c->reply));
 186     }
 187     redisProtocolToLuaType(lua,reply);
 188     sdsfree(reply);
 189
 190     /* Clean up. Command code may have changed argv/argc so we use the
 191      * argv/argc of the client instead of the local variables. */
 192     for (j = 0; j < c->argc; j++)
 193         decrRefCount(c->argv[j]);
 194     zfree(c->argv);
 195
 196     return 1;
 197 }
 198
 199 void scriptingInit(void) {
 200     lua_State *lua = lua_open();
 201     luaL_openlibs(lua);
 202
 203     /* Register the 'r' command */
 204     lua_pushcfunction(lua,luaRedisCommand);
 205     lua_setglobal(lua,"redis");
 206
 207     /* Create the (non connected) client that we use to execute Redis commands
 208      * inside the Lua interpreter */
 209     server.lua_client = createClient(-1);
 210     server.lua_client->flags |= REDIS_LUA_CLIENT;
 211
 212     server.lua = lua;
 213 }
 214
 215 /* Hash the scripit into a SHA1 digest. We use this as Lua function name.
 216  * Digest should point to a 41 bytes buffer: 40 for SHA1 converted into an
 217  * hexadecimal number, plus 1 byte for null term. */
 218 void hashScript(char *digest, char *script, size_t len) {
 219     SHA1_CTX ctx;
 220     unsigned char hash[20];
 221     char *cset = "0123456789abcdef";
 222     int j;
 223
 224     SHA1Init(&ctx);
 225     SHA1Update(&ctx,(unsigned char*)script,len);
 226     SHA1Final(hash,&ctx);
 227
 228     for (j = 0; j < 20; j++) {
 229         digest[j*2] = cset[((hash[j]&0xF0)>>4)];
 230         digest[j*2+1] = cset[(hash[j]&0xF)];
 231     }
 232     digest[40] = '\0';
 233 }
 234
 235 void luaReplyToRedisReply(redisClient *c, lua_State *lua) {
 236     int t = lua_type(lua,1);
 237
 238     switch(t) {
 239     case LUA_TSTRING:
 240         addReplyBulkCBuffer(c,(char*)lua_tostring(lua,1),lua_strlen(lua,1));
 241         break;
 242     case LUA_TBOOLEAN:
 243         addReply(c,lua_toboolean(lua,1) ? shared.cone : shared.czero);
 244         break;
 245     case LUA_TNUMBER:
 246         addReplyLongLong(c,(long long)lua_tonumber(lua,1));
 247         break;
 248     case LUA_TTABLE:
 249         /* We need to check if it is an array or an error.
 250          * Error are returned as a single element table with 'err' field. */
 251         lua_pushstring(lua,"err");
 252         lua_gettable(lua,-2);
 253         t = lua_type(lua,-1);
 254         if (t == LUA_TSTRING) {
 255             addReplySds(c,sdscatprintf(sdsempty(),
 256                     "-%s\r\n",(char*)lua_tostring(lua,-1)));
 257             lua_pop(lua,1);
 258         } else {
 259             void *replylen = addDeferredMultiBulkLength(c);
 260             int j = 1, mbulklen = 0;
 261
 262             lua_pop(lua,1); /* Discard the 'err' field value we popped */
 263             while(1) {
 264                 lua_pushnumber(lua,j++);
 265                 lua_gettable(lua,-2);
 266                 t = lua_type(lua,-1);
 267                 if (t == LUA_TNIL) {
 268                     lua_pop(lua,1);
 269                     break;
 270                 } else if (t == LUA_TSTRING) {
 271                     size_t len;
 272                     char *s = (char*) lua_tolstring(lua,-1,&len);
 273
 274                     addReplyBulkCBuffer(c,s,len);
 275                     mbulklen++;
 276                 } else if (t == LUA_TNUMBER) {
 277                     addReplyLongLong(c,(long long)lua_tonumber(lua,-1));
 278                     mbulklen++;
 279                 }
 280                 lua_pop(lua,1);
 281             }
 282             setDeferredMultiBulkLength(c,replylen,mbulklen);
 283         }
 284         break;
 285     default:
 286         addReply(c,shared.nullbulk);
 287     }
 288     lua_pop(lua,1);
 289 }
 290
 291 /* Set an array of Redis String Objects as a Lua array (table) stored into a
 292  * global variable. */
 293 void luaSetGlobalArray(lua_State *lua, char *var, robj **elev, int elec) {
 294     int j;
 295
 296     lua_newtable(lua);
 297     for (j = 0; j < elec; j++) {
 298         lua_pushlstring(lua,(char*)elev[j]->ptr,sdslen(elev[j]->ptr));
 299         lua_rawseti(lua,-2,j+1);
 300     }
 301     lua_setglobal(lua,var);
 302 }
 303
 304 void evalCommand(redisClient *c) {
 305     lua_State *lua = server.lua;
 306     char funcname[43];
 307     long long numkeys;
 308
 309     /* Get the number of arguments that are keys */
 310     if (getLongLongFromObjectOrReply(c,c->argv[2],&numkeys,NULL) != REDIS_OK)
 311         return;
 312     if (numkeys > (c->argc - 3)) {
 313         addReplyError(c,"Number of keys can't be greater than number of args");
 314         return;
 315     }
 316
 317     /* We obtain the script SHA1, then check if this function is already
 318      * defined into the Lua state */
 319     funcname[0] = 'f';
 320     funcname[1] = '_';
 321     hashScript(funcname+2,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
 322     lua_getglobal(lua, funcname);
 323     if (lua_isnil(lua,1)) {
 324         /* Function not defined... let's define it. */
 325         sds funcdef = sdsempty();
 326
 327         lua_pop(lua,1); /* remove the nil from the stack */
 328         funcdef = sdscat(funcdef,"function ");
 329         funcdef = sdscatlen(funcdef,funcname,42);
 330         funcdef = sdscatlen(funcdef," ()\n",4);
 331         funcdef = sdscatlen(funcdef,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
 332         funcdef = sdscatlen(funcdef,"\nend\n",5);
 333         /* printf("Defining:\n%s\n",funcdef); */
 334
 335         if (luaL_loadbuffer(lua,funcdef,sdslen(funcdef),"func definition")) {
 336             addReplyErrorFormat(c,"Error compiling script (new function): %s\n",
 337                 lua_tostring(lua,-1));
 338             lua_pop(lua,1);
 339             sdsfree(funcdef);
 340             return;
 341         }
 342         sdsfree(funcdef);
 343         if (lua_pcall(lua,0,0,0)) {
 344             addReplyErrorFormat(c,"Error running script (new function): %s\n",
 345                 lua_tostring(lua,-1));
 346             lua_pop(lua,1);
 347             return;
 348         }
 349         lua_getglobal(lua, funcname);
 350     }
 351
 352     /* Populate the argv and keys table accordingly to the arguments that
 353      * EVAL received. */
 354     luaSetGlobalArray(lua,"KEYS",c->argv+3,numkeys);
 355     luaSetGlobalArray(lua,"ARGV",c->argv+3+numkeys,c->argc-3-numkeys);
 356
 357     /* At this point whatever this script was never seen before or if it was
 358      * already defined, we can call it. We have zero arguments and expect
 359      * a single return value. */
 360     if (lua_pcall(lua,0,1,0)) {
 361         addReplyErrorFormat(c,"Error running script (call to %s): %s\n",
 362             funcname, lua_tostring(lua,-1));
 363         lua_pop(lua,1);
 364         return;
 365     }
 366     luaReplyToRedisReply(c,lua);
 367 }