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