src/debug.c

   1 #include "redis.h"
   2 #include "sha1.h"   /* SHA1 is used for DEBUG DIGEST */
   3
   4 #include <arpa/inet.h>
   5
   6 /* ================================= Debugging ============================== */
   7
   8 /* Compute the sha1 of string at 's' with 'len' bytes long.
   9  * The SHA1 is then xored againt the string pointed by digest.
  10  * Since xor is commutative, this operation is used in order to
  11  * "add" digests relative to unordered elements.
  12  *
  13  * So digest(a,b,c,d) will be the same of digest(b,a,c,d) */
  14 void xorDigest(unsigned char *digest, void *ptr, size_t len) {
  15     SHA1_CTX ctx;
  16     unsigned char hash[20], *s = ptr;
  17     int j;
  18
  19     SHA1Init(&ctx);
  20     SHA1Update(&ctx,s,len);
  21     SHA1Final(hash,&ctx);
  22
  23     for (j = 0; j < 20; j++)
  24         digest[j] ^= hash[j];
  25 }
  26
  27 void xorObjectDigest(unsigned char *digest, robj *o) {
  28     o = getDecodedObject(o);
  29     xorDigest(digest,o->ptr,sdslen(o->ptr));
  30     decrRefCount(o);
  31 }
  32
  33 /* This function instead of just computing the SHA1 and xoring it
  34  * against diget, also perform the digest of "digest" itself and
  35  * replace the old value with the new one.
  36  *
  37  * So the final digest will be:
  38  *
  39  * digest = SHA1(digest xor SHA1(data))
  40  *
  41  * This function is used every time we want to preserve the order so
  42  * that digest(a,b,c,d) will be different than digest(b,c,d,a)
  43  *
  44  * Also note that mixdigest("foo") followed by mixdigest("bar")
  45  * will lead to a different digest compared to "fo", "obar".
  46  */
  47 void mixDigest(unsigned char *digest, void *ptr, size_t len) {
  48     SHA1_CTX ctx;
  49     char *s = ptr;
  50
  51     xorDigest(digest,s,len);
  52     SHA1Init(&ctx);
  53     SHA1Update(&ctx,digest,20);
  54     SHA1Final(digest,&ctx);
  55 }
  56
  57 void mixObjectDigest(unsigned char *digest, robj *o) {
  58     o = getDecodedObject(o);
  59     mixDigest(digest,o->ptr,sdslen(o->ptr));
  60     decrRefCount(o);
  61 }
  62
  63 /* Compute the dataset digest. Since keys, sets elements, hashes elements
  64  * are not ordered, we use a trick: every aggregate digest is the xor
  65  * of the digests of their elements. This way the order will not change
  66  * the result. For list instead we use a feedback entering the output digest
  67  * as input in order to ensure that a different ordered list will result in
  68  * a different digest. */
  69 void computeDatasetDigest(unsigned char *final) {
  70     unsigned char digest[20];
  71     char buf[128];
  72     dictIterator *di = NULL;
  73     dictEntry *de;
  74     int j;
  75     uint32_t aux;
  76
  77     memset(final,0,20); /* Start with a clean result */
  78
  79     for (j = 0; j < server.dbnum; j++) {
  80         redisDb *db = server.db+j;
  81
  82         if (dictSize(db->dict) == 0) continue;
  83         di = dictGetIterator(db->dict);
  84
  85         /* hash the DB id, so the same dataset moved in a different
  86          * DB will lead to a different digest */
  87         aux = htonl(j);
  88         mixDigest(final,&aux,sizeof(aux));
  89
  90         /* Iterate this DB writing every entry */
  91         while((de = dictNext(di)) != NULL) {
  92             sds key;
  93             robj *keyobj, *o;
  94             time_t expiretime;
  95
  96             memset(digest,0,20); /* This key-val digest */
  97             key = dictGetEntryKey(de);
  98             keyobj = createStringObject(key,sdslen(key));
  99
 100             mixDigest(digest,key,sdslen(key));
 101
 102             /* Make sure the key is loaded if VM is active */
 103             o = lookupKeyRead(db,keyobj);
 104
 105             aux = htonl(o->type);
 106             mixDigest(digest,&aux,sizeof(aux));
 107             expiretime = getExpire(db,keyobj);
 108
 109             /* Save the key and associated value */
 110             if (o->type == REDIS_STRING) {
 111                 mixObjectDigest(digest,o);
 112             } else if (o->type == REDIS_LIST) {
 113                 listTypeIterator *li = listTypeInitIterator(o,0,REDIS_TAIL);
 114                 listTypeEntry entry;
 115                 while(listTypeNext(li,&entry)) {
 116                     robj *eleobj = listTypeGet(&entry);
 117                     mixObjectDigest(digest,eleobj);
 118                     decrRefCount(eleobj);
 119                 }
 120                 listTypeReleaseIterator(li);
 121             } else if (o->type == REDIS_SET) {
 122                 setTypeIterator *si = setTypeInitIterator(o);
 123                 robj *ele;
 124                 while((ele = setTypeNextObject(si)) != NULL) {
 125                     xorObjectDigest(digest,ele);
 126                     decrRefCount(ele);
 127                 }
 128                 setTypeReleaseIterator(si);
 129             } else if (o->type == REDIS_ZSET) {
 130                 zset *zs = o->ptr;
 131                 dictIterator *di = dictGetIterator(zs->dict);
 132                 dictEntry *de;
 133
 134                 while((de = dictNext(di)) != NULL) {
 135                     robj *eleobj = dictGetEntryKey(de);
 136                     double *score = dictGetEntryVal(de);
 137                     unsigned char eledigest[20];
 138
 139                     snprintf(buf,sizeof(buf),"%.17g",*score);
 140                     memset(eledigest,0,20);
 141                     mixObjectDigest(eledigest,eleobj);
 142                     mixDigest(eledigest,buf,strlen(buf));
 143                     xorDigest(digest,eledigest,20);
 144                 }
 145                 dictReleaseIterator(di);
 146             } else if (o->type == REDIS_HASH) {
 147                 hashTypeIterator *hi;
 148                 robj *obj;
 149
 150                 hi = hashTypeInitIterator(o);
 151                 while (hashTypeNext(hi) != REDIS_ERR) {
 152                     unsigned char eledigest[20];
 153
 154                     memset(eledigest,0,20);
 155                     obj = hashTypeCurrentObject(hi,REDIS_HASH_KEY);
 156                     mixObjectDigest(eledigest,obj);
 157                     decrRefCount(obj);
 158                     obj = hashTypeCurrentObject(hi,REDIS_HASH_VALUE);
 159                     mixObjectDigest(eledigest,obj);
 160                     decrRefCount(obj);
 161                     xorDigest(digest,eledigest,20);
 162                 }
 163                 hashTypeReleaseIterator(hi);
 164             } else {
 165                 redisPanic("Unknown object type");
 166             }
 167             /* If the key has an expire, add it to the mix */
 168             if (expiretime != -1) xorDigest(digest,"!!expire!!",10);
 169             /* We can finally xor the key-val digest to the final digest */
 170             xorDigest(final,digest,20);
 171             decrRefCount(keyobj);
 172         }
 173         dictReleaseIterator(di);
 174     }
 175 }
 176
 177 void debugCommand(redisClient *c) {
 178     if (!strcasecmp(c->argv[1]->ptr,"segfault")) {
 179         *((char*)-1) = 'x';
 180     } else if (!strcasecmp(c->argv[1]->ptr,"reload")) {
 181         if (rdbSave(server.dbfilename) != REDIS_OK) {
 182             addReply(c,shared.err);
 183             return;
 184         }
 185         emptyDb();
 186         if (rdbLoad(server.dbfilename) != REDIS_OK) {
 187             addReply(c,shared.err);
 188             return;
 189         }
 190         redisLog(REDIS_WARNING,"DB reloaded by DEBUG RELOAD");
 191         addReply(c,shared.ok);
 192     } else if (!strcasecmp(c->argv[1]->ptr,"loadaof")) {
 193         emptyDb();
 194         if (loadAppendOnlyFile(server.appendfilename) != REDIS_OK) {
 195             addReply(c,shared.err);
 196             return;
 197         }
 198         redisLog(REDIS_WARNING,"Append Only File loaded by DEBUG LOADAOF");
 199         addReply(c,shared.ok);
 200     } else if (!strcasecmp(c->argv[1]->ptr,"object") && c->argc == 3) {
 201         dictEntry *de = dictFind(c->db->dict,c->argv[2]->ptr);
 202         robj *val;
 203         char *strenc;
 204         char *storage;
 205
 206         if (!de) {
 207             addReply(c,shared.nokeyerr);
 208             return;
 209         }
 210         val = dictGetEntryVal(de);
 211         strenc = strEncoding(val->encoding);
 212         switch(val->storage) {
 213         case REDIS_DS_MEMORY: storage = "memory"; break;
 214         case REDIS_DS_DIRTY: storage = "dirty"; break;
 215         case REDIS_DS_SAVING: storage = "saving"; break;
 216         default: storage = "unknown"; break;
 217         }
 218         addReplyStatusFormat(c,
 219             "Value at:%p refcount:%d "
 220             "encoding:%s serializedlength:%lld "
 221             "lru:%d lru_seconds_idle:%lu storage:%s",
 222             (void*)val, val->refcount,
 223             strenc, (long long) rdbSavedObjectLen(val),
 224             val->lru, estimateObjectIdleTime(val), storage);
 225     } else if (!strcasecmp(c->argv[1]->ptr,"populate") && c->argc == 3) {
 226         long keys, j;
 227         robj *key, *val;
 228         char buf[128];
 229
 230         if (getLongFromObjectOrReply(c, c->argv[2], &keys, NULL) != REDIS_OK)
 231             return;
 232         for (j = 0; j < keys; j++) {
 233             snprintf(buf,sizeof(buf),"key:%lu",j);
 234             key = createStringObject(buf,strlen(buf));
 235             if (lookupKeyRead(c->db,key) != NULL) {
 236                 decrRefCount(key);
 237                 continue;
 238             }
 239             snprintf(buf,sizeof(buf),"value:%lu",j);
 240             val = createStringObject(buf,strlen(buf));
 241             dbAdd(c->db,key,val);
 242             decrRefCount(key);
 243         }
 244         addReply(c,shared.ok);
 245     } else if (!strcasecmp(c->argv[1]->ptr,"digest") && c->argc == 2) {
 246         unsigned char digest[20];
 247         sds d = sdsempty();
 248         int j;
 249
 250         computeDatasetDigest(digest);
 251         for (j = 0; j < 20; j++)
 252             d = sdscatprintf(d, "%02x",digest[j]);
 253         addReplyStatus(c,d);
 254         sdsfree(d);
 255     } else {
 256         addReplyError(c,
 257             "Syntax error, try DEBUG [SEGFAULT|OBJECT <key>|SWAPIN <key>|SWAPOUT <key>|RELOAD]");
 258     }
 259 }
 260
 261 void _redisAssert(char *estr, char *file, int line) {
 262     redisLog(REDIS_WARNING,"=== ASSERTION FAILED ===");
 263     redisLog(REDIS_WARNING,"==> %s:%d '%s' is not true",file,line,estr);
 264 #ifdef HAVE_BACKTRACE
 265     redisLog(REDIS_WARNING,"(forcing SIGSEGV in order to print the stack trace)");
 266     *((char*)-1) = 'x';
 267 #endif
 268 }
 269
 270 void _redisPanic(char *msg, char *file, int line) {
 271     redisLog(REDIS_WARNING,"!!! Software Failure. Press left mouse button to continue");
 272     redisLog(REDIS_WARNING,"Guru Meditation: %s #%s:%d",msg,file,line);
 273 #ifdef HAVE_BACKTRACE
 274     redisLog(REDIS_WARNING,"(forcing SIGSEGV in order to print the stack trace)");
 275     *((char*)-1) = 'x';
 276 #endif
 277 }