clean up nonce implementation

bson/oid.cpp

@@ -34,7 +34,7 @@ namespace mongo {
 #elif defined(__linux__) || defined(__APPLE__) || defined(__sunos__)
         pid = (unsigned short) getpid();
 #else
-        pid = (unsigned short) security.getNonce();
+        pid = (unsigned short) Security::getNonce();
 #endif
         return pid;
     }
@@ -53,13 +53,13 @@ namespace mongo {
         // this is not called often, so the following is not expensive, and gives us some
         // testing that nonce generation is working right and that our OIDs are (perhaps) ok.
         {
-            nonce a = security.getNonce();
-            nonce b = security.getNonce();
-            nonce c = security.getNonce();
+            nonce64 a = Security::getNonceDuringInit();
+            nonce64 b = Security::getNonceDuringInit();
+            nonce64 c = Security::getNonceDuringInit();
             assert( !(a==b && b==c) );
         }
 
-        unsigned long long n = security.getNonce();
+        unsigned long long n = Security::getNonceDuringInit();
         OID::MachineAndPid x = ourMachine = (OID::MachineAndPid&) n;
         foldInPid(x);
         return x;
@@ -96,7 +96,7 @@ namespace mongo {
     }
 
     void OID::init() {
-        static AtomicUInt inc = (unsigned) security.getNonce();
+        static AtomicUInt inc = (unsigned) Security::getNonce();
 
         {
             unsigned t = (unsigned) time(0);

db/dur_journal.cpp

@@ -41,6 +41,8 @@ namespace mongo {
 
     class AlignedBuilder;
 
+    unsigned goodRandomNumberSlow();
+
     namespace dur {
         // Rotate after reaching this data size in a journal (j._<n>) file
         // We use a smaller size for 32 bit as the journal is mmapped during recovery (only)
@@ -118,15 +120,13 @@ namespace mongo {
             strncpy(dbpath, fname.c_str(), sizeof(dbpath)-1);
             {
                 fileId = t&0xffffffff;
-                fileId |= ((unsigned long long)getRandomNumber()) << 32;
+                fileId |= ((unsigned long long)goodRandomNumberSlow()) << 32;
             }
             memset(reserved3, 0, sizeof(reserved3));
             txt2[0] = txt2[1] = '\n';
             n1 = n2 = n3 = n4 = '\n';
         }
 
-        // class Journal
-
         Journal j;
 
         const unsigned long long LsnShutdownSentinel = ~((unsigned long long)0);

db/nonce.cpp

@@ -23,7 +23,9 @@ extern int do_md5_test(void);
 
 namespace mongo {
 
-    BOOST_STATIC_ASSERT( sizeof(nonce) == 8 );
+    BOOST_STATIC_ASSERT( sizeof(nonce64) == 8 );
+
+    static Security security; // needs to be static so _initialized is preset to false (see initsafe below)
 
     Security::Security() {
         static int n;
@@ -31,7 +33,7 @@ namespace mongo {
         init();
     }
 
-    void Security::init() {
+    NOINLINE_DECL void Security::init() {
         if( _initialized ) return;
         _initialized = true;
 
@@ -39,7 +41,7 @@ namespace mongo {
         _devrandom = new ifstream("/dev/urandom", ios::binary|ios::in);
         massert( 10353 ,  "can't open dev/urandom", _devrandom->is_open() );
 #elif defined(_WIN32)
-        srand(curTimeMicros());
+        srand(curTimeMicros()); // perhaps not relevant for rand_s but we might want elsewhere anyway
 #else
         srandomdev();
 #endif
@@ -50,21 +52,12 @@ namespace mongo {
 #endif
     }
 
-    nonce Security::getNonce() {
-        static mongo::mutex m("getNonce");
-        scoped_lock lk(m);
-        
-        if ( ! _initialized )
-            init();
-
-        /* question/todo: /dev/random works on OS X.  is it better
-           to use that than random() / srandom()?
-        */
-
-        nonce n;
+    nonce64 Security::__getNonce() { 
+        dassert( _initialized );
+        nonce64 n;
 #if defined(__linux__) || defined(__sunos__) || defined(__APPLE__)
         _devrandom->read((char*)&n, sizeof(n));
-        massert( 10355 , "devrandom failed", !_devrandom->fail());
+        massert(10355 , "devrandom failed", !_devrandom->fail());
 #elif defined(_WIN32)
         unsigned a=0, b=0;
         assert( rand_s(&a) == 0 );
@@ -75,9 +68,28 @@ namespace mongo {
 #endif
         return n;
     }
-    unsigned getRandomNumber() { return (unsigned) security.getNonce(); }
 
-    bool Security::_initialized;
-    Security security;
+    SimpleMutex nonceMutex("nonce");
+    nonce64 Security::_getNonce() {
+        // not good this is a static as gcc will mutex protect it which costs time
+        SimpleMutex::scoped_lock lk(nonceMutex);
+        if( !_initialized )
+            init();
+        return __getNonce();
+    }
+
+    nonce64 Security::getNonceDuringInit() {
+        // the mutex might not be inited yet.  init phase should be one thread anyway (hopefully we don't spawn threads therein)
+        if( !security._initialized )
+            security.init();
+        return security.__getNonce();
+    }
+
+    nonce64 Security::getNonce() {
+        return security._getNonce();
+    }
+
+    // name warns us this might be a little slow (see code above)
+    unsigned goodRandomNumberSlow() { return (unsigned) Security::getNonce(); }
 
 } // namespace mongo

db/nonce.h

@@ -1,4 +1,4 @@
-// nonce.h
+// @file nonce.h
 
 /*    Copyright 2009 10gen Inc.
  *
@@ -19,24 +19,18 @@
 
 namespace mongo {
 
-    typedef unsigned long long nonce;
+    typedef unsigned long long nonce64;
 
     struct Security {
         Security();
-
-        nonce getNonce();
-
-        /** safe during global var initialization */
-        nonce getNonceInitSafe() {
-            init();
-            return getNonce();
-        }
+        static nonce64 getNonce();
+        static nonce64 getNonceDuringInit(); // use this version during global var constructors
     private:
+        nonce64 _getNonce();
+        nonce64 __getNonce();
         ifstream *_devrandom;
-        static bool _initialized;
+        bool _initialized;
         void init(); // can call more than once
     };
 
-    extern Security security;
-
 } // namespace mongo

db/security_commands.cpp

@@ -39,12 +39,12 @@ namespace mongo {
 
        getnonce sends nonce to client
 
-       client then sends { authenticate:1, nonce:<nonce_str>, user:<username>, key:<key> }
+       client then sends { authenticate:1, nonce64:<nonce_str>, user:<username>, key:<key> }
 
        where <key> is md5(<nonce_str><username><pwd_digest_str>) as a string
     */
 
-    boost::thread_specific_ptr<nonce> lastNonce;
+    boost::thread_specific_ptr<nonce64> lastNonce;
 
     class CmdGetNonce : public Command {
     public:
@@ -57,7 +57,7 @@ namespace mongo {
         virtual LockType locktype() const { return NONE; }
         CmdGetNonce() : Command("getnonce") {}
         bool run(const string&, BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
-            nonce *n = new nonce(security.getNonce());
+            nonce64 *n = new nonce64(Security::getNonce());
             stringstream ss;
             ss << hex << *n;
             result.append("nonce", ss.str() );
@@ -116,7 +116,7 @@ namespace mongo {
 
             {
                 bool reject = false;
-                nonce *ln = lastNonce.release();
+                nonce64 *ln = lastNonce.release();
                 if ( ln == 0 ) {
                     reject = true;
                     log(1) << "auth: no lastNonce" << endl;

s/cursors.cpp

@@ -184,7 +184,7 @@ namespace mongo {
 
     long long CursorCache::genId() {
         while ( true ) {
-            long long x = security.getNonce();
+            long long x = Security::getNonce();
             if ( x == 0 )
                 continue;
             if ( x < 0 )

shell/mongo_vstudio.cpp

@@ -1744,8 +1744,8 @@ const StringData _jscode_raw_db =
 "this.getCollection( \"system.users\" ).remove( { user : username } );\n" 
 "}\n" 
 "\n" 
-"DB.prototype.__pwHash = function( nonce, username, pass ) {\n" 
-"return hex_md5( nonce + username + hex_md5( username + \":mongo:\" + pass ) );\n" 
+"DB.prototype.__pwHash = function( nonce64, username, pass ) {\n" 
+"return hex_md5( nonce64 + username + hex_md5( username + \":mongo:\" + pass ) );\n" 
 "}\n" 
 "\n" 
 "DB.prototype.auth = function( username , pass ){\n" 
@@ -1755,8 +1755,8 @@ const StringData _jscode_raw_db =
 "{\n" 
 "authenticate : 1 ,\n" 
 "user : username ,\n" 
-"nonce : n.nonce ,\n" 
-"key : this.__pwHash( n.nonce, username, pass )\n" 
+"nonce64 : n.nonce64 ,\n" 
+"key : this.__pwHash( n.nonce64, username, pass )\n" 
 "}\n" 
 ");\n" 
 "\n" 
@@ -1925,7 +1925,7 @@ const StringData _jscode_raw_db =
 "fromhost = fromhost || \"\";\n" 
 "if ( username && password ) {\n" 
 "var n = this._adminCommand( { copydbgetnonce : 1, fromhost:fromhost } );\n" 
-"return this._adminCommand( { copydb:1, fromhost:fromhost, fromdb:fromdb, todb:todb, username:username, nonce:n.nonce, key:this.__pwHash( n.nonce, username, password ) } );\n" 
+"return this._adminCommand( { copydb:1, fromhost:fromhost, fromdb:fromdb, todb:todb, username:username, nonce64:n.nonce64, key:this.__pwHash( n.nonce64, username, password ) } );\n" 
 "} else {\n" 
 "return this._adminCommand( { copydb:1, fromhost:fromhost, fromdb:fromdb, todb:todb } );\n" 
 "}\n"