src/migrate.c

   1 #include "redis.h"
   2 #include "endianconv.h"
   3
   4 /* -----------------------------------------------------------------------------
   5  * DUMP, RESTORE and MIGRATE commands
   6  * -------------------------------------------------------------------------- */
   7
   8 /* Generates a DUMP-format representation of the object 'o', adding it to the
   9  * io stream pointed by 'rio'. This function can't fail. */
  10 void createDumpPayload(rio *payload, robj *o) {
  11     unsigned char buf[2];
  12     uint64_t crc;
  13
  14     /* Serialize the object in a RDB-like format. It consist of an object type
  15      * byte followed by the serialized object. This is understood by RESTORE. */
  16     rioInitWithBuffer(payload,sdsempty());
  17     redisAssert(rdbSaveObjectType(payload,o));
  18     redisAssert(rdbSaveObject(payload,o));
  19
  20     /* Write the footer, this is how it looks like:
  21      * ----------------+---------------------+---------------+
  22      * ... RDB payload | 2 bytes RDB version | 8 bytes CRC64 |
  23      * ----------------+---------------------+---------------+
  24      * RDB version and CRC are both in little endian.
  25      */
  26
  27     /* RDB version */
  28     buf[0] = REDIS_RDB_VERSION & 0xff;
  29     buf[1] = (REDIS_RDB_VERSION >> 8) & 0xff;
  30     payload->io.buffer.ptr = sdscatlen(payload->io.buffer.ptr,buf,2);
  31
  32     /* CRC64 */
  33     crc = crc64(0,(unsigned char*)payload->io.buffer.ptr,
  34                 sdslen(payload->io.buffer.ptr));
  35     memrev64ifbe(&crc);
  36     payload->io.buffer.ptr = sdscatlen(payload->io.buffer.ptr,&crc,8);
  37 }
  38
  39 /* Verify that the RDB version of the dump payload matches the one of this Redis
  40  * instance and that the checksum is ok.
  41  * If the DUMP payload looks valid REDIS_OK is returned, otherwise REDIS_ERR
  42  * is returned. */
  43 int verifyDumpPayload(unsigned char *p, size_t len) {
  44     unsigned char *footer;
  45     uint16_t rdbver;
  46     uint64_t crc;
  47
  48     /* At least 2 bytes of RDB version and 8 of CRC64 should be present. */
  49     if (len < 10) return REDIS_ERR;
  50     footer = p+(len-10);
  51
  52     /* Verify RDB version */
  53     rdbver = (footer[1] << 8) | footer[0];
  54     if (rdbver != REDIS_RDB_VERSION) return REDIS_ERR;
  55
  56     /* Verify CRC64 */
  57     crc = crc64(0,p,len-8);
  58     memrev64ifbe(&crc);
  59     return (memcmp(&crc,footer+2,8) == 0) ? REDIS_OK : REDIS_ERR;
  60 }
  61
  62 /* DUMP keyname
  63  * DUMP is actually not used by Redis Cluster but it is the obvious
  64  * complement of RESTORE and can be useful for different applications. */
  65 void dumpCommand(redisClient *c) {
  66     robj *o, *dumpobj;
  67     rio payload;
  68
  69     /* Check if the key is here. */
  70     if ((o = lookupKeyRead(c->db,c->argv[1])) == NULL) {
  71         addReply(c,shared.nullbulk);
  72         return;
  73     }
  74
  75     /* Create the DUMP encoded representation. */
  76     createDumpPayload(&payload,o);
  77
  78     /* Transfer to the client */
  79     dumpobj = createObject(REDIS_STRING,payload.io.buffer.ptr);
  80     addReplyBulk(c,dumpobj);
  81     decrRefCount(dumpobj);
  82     return;
  83 }
  84
  85 /* RESTORE key ttl serialized-value */
  86 void restoreCommand(redisClient *c) {
  87     long ttl;
  88     rio payload;
  89     int type;
  90     robj *obj;
  91
  92     /* Make sure this key does not already exist here... */
  93     if (lookupKeyWrite(c->db,c->argv[1]) != NULL) {
  94         addReplyError(c,"Target key name is busy.");
  95         return;
  96     }
  97
  98     /* Check if the TTL value makes sense */
  99     if (getLongFromObjectOrReply(c,c->argv[2],&ttl,NULL) != REDIS_OK) {
 100         return;
 101     } else if (ttl < 0) {
 102         addReplyError(c,"Invalid TTL value, must be >= 0");
 103         return;
 104     }
 105
 106     /* Verify RDB version and data checksum. */
 107     if (verifyDumpPayload(c->argv[3]->ptr,sdslen(c->argv[3]->ptr)) == REDIS_ERR) {
 108         addReplyError(c,"DUMP payload version or checksum are wrong");
 109         return;
 110     }
 111
 112     rioInitWithBuffer(&payload,c->argv[3]->ptr);
 113     if (((type = rdbLoadObjectType(&payload)) == -1) ||
 114         ((obj = rdbLoadObject(type,&payload)) == NULL))
 115     {
 116         addReplyError(c,"Bad data format");
 117         return;
 118     }
 119
 120     /* Create the key and set the TTL if any */
 121     dbAdd(c->db,c->argv[1],obj);
 122     if (ttl) setExpire(c->db,c->argv[1],mstime()+ttl);
 123     signalModifiedKey(c->db,c->argv[1]);
 124     addReply(c,shared.ok);
 125     server.dirty++;
 126 }
 127
 128 /* MIGRATE host port key dbid timeout */
 129 void migrateCommand(redisClient *c) {
 130     int fd;
 131     long timeout;
 132     long dbid;
 133     long long ttl = 0, expireat;
 134     robj *o;
 135     rio cmd, payload;
 136
 137     /* Sanity check */
 138     if (getLongFromObjectOrReply(c,c->argv[5],&timeout,NULL) != REDIS_OK)
 139         return;
 140     if (getLongFromObjectOrReply(c,c->argv[4],&dbid,NULL) != REDIS_OK)
 141         return;
 142     if (timeout <= 0) timeout = 1;
 143
 144     /* Check if the key is here. If not we reply with success as there is
 145      * nothing to migrate (for instance the key expired in the meantime), but
 146      * we include such information in the reply string. */
 147     if ((o = lookupKeyRead(c->db,c->argv[3])) == NULL) {
 148         addReplySds(c,sdsnew("+NOKEY\r\n"));
 149         return;
 150     }
 151
 152     /* Connect */
 153     fd = anetTcpNonBlockConnect(server.neterr,c->argv[1]->ptr,
 154                 atoi(c->argv[2]->ptr));
 155     if (fd == -1) {
 156         addReplyErrorFormat(c,"Can't connect to target node: %s",
 157             server.neterr);
 158         return;
 159     }
 160     if ((aeWait(fd,AE_WRITABLE,timeout*1000) & AE_WRITABLE) == 0) {
 161         addReplySds(c,sdsnew("-IOERR error or timeout connecting to the client\r\n"));
 162         return;
 163     }
 164
 165     /* Create RESTORE payload and generate the protocol to call the command. */
 166     rioInitWithBuffer(&cmd,sdsempty());
 167     redisAssertWithInfo(c,NULL,rioWriteBulkCount(&cmd,'*',2));
 168     redisAssertWithInfo(c,NULL,rioWriteBulkString(&cmd,"SELECT",6));
 169     redisAssertWithInfo(c,NULL,rioWriteBulkLongLong(&cmd,dbid));
 170
 171     expireat = getExpire(c->db,c->argv[3]);
 172     if (expireat != -1) {
 173         ttl = expireat-mstime();
 174         if (ttl < 1) ttl = 1;
 175     }
 176     redisAssertWithInfo(c,NULL,rioWriteBulkCount(&cmd,'*',4));
 177     redisAssertWithInfo(c,NULL,rioWriteBulkString(&cmd,"RESTORE",7));
 178     redisAssertWithInfo(c,NULL,c->argv[3]->encoding == REDIS_ENCODING_RAW);
 179     redisAssertWithInfo(c,NULL,rioWriteBulkString(&cmd,c->argv[3]->ptr,sdslen(c->argv[3]->ptr)));
 180     redisAssertWithInfo(c,NULL,rioWriteBulkLongLong(&cmd,ttl));
 181
 182     /* Finally the last argument that is the serailized object payload
 183      * in the DUMP format. */
 184     createDumpPayload(&payload,o);
 185     redisAssertWithInfo(c,NULL,rioWriteBulkString(&cmd,payload.io.buffer.ptr,
 186                                 sdslen(payload.io.buffer.ptr)));
 187     sdsfree(payload.io.buffer.ptr);
 188
 189     /* Tranfer the query to the other node in 64K chunks. */
 190     {
 191         sds buf = cmd.io.buffer.ptr;
 192         size_t pos = 0, towrite;
 193         int nwritten = 0;
 194
 195         while ((towrite = sdslen(buf)-pos) > 0) {
 196             towrite = (towrite > (64*1024) ? (64*1024) : towrite);
 197             nwritten = syncWrite(fd,buf+pos,towrite,timeout);
 198             if (nwritten != (signed)towrite) goto socket_wr_err;
 199             pos += nwritten;
 200         }
 201     }
 202
 203     /* Read back the reply. */
 204     {
 205         char buf1[1024];
 206         char buf2[1024];
 207
 208         /* Read the two replies */
 209         if (syncReadLine(fd, buf1, sizeof(buf1), timeout) <= 0)
 210             goto socket_rd_err;
 211         if (syncReadLine(fd, buf2, sizeof(buf2), timeout) <= 0)
 212             goto socket_rd_err;
 213         if (buf1[0] == '-' || buf2[0] == '-') {
 214             addReplyErrorFormat(c,"Target instance replied with error: %s",
 215                 (buf1[0] == '-') ? buf1+1 : buf2+1);
 216         } else {
 217             robj *aux;
 218
 219             dbDelete(c->db,c->argv[3]);
 220             signalModifiedKey(c->db,c->argv[3]);
 221             addReply(c,shared.ok);
 222             server.dirty++;
 223
 224             /* Translate MIGRATE as DEL for replication/AOF. */
 225             aux = createStringObject("DEL",3);
 226             rewriteClientCommandVector(c,2,aux,c->argv[3]);
 227             decrRefCount(aux);
 228         }
 229     }
 230
 231     sdsfree(cmd.io.buffer.ptr);
 232     close(fd);
 233     return;
 234
 235 socket_wr_err:
 236     addReplySds(c,sdsnew("-IOERR error or timeout writing to target instance\r\n"));
 237     sdsfree(cmd.io.buffer.ptr);
 238     close(fd);
 239     return;
 240
 241 socket_rd_err:
 242     addReplySds(c,sdsnew("-IOERR error or timeout reading from target node\r\n"));
 243     sdsfree(cmd.io.buffer.ptr);
 244     close(fd);
 245     return;
 246 }