SCRUM: Secure auth

Implement mysql_change_user
Get rid of double user search at authentication
Some cleanups

4 files changed, 331 insertions, 215 deletions

diff --git a/sql/password.c b/sql/password.c
index b9eb6012354..98cac1e07d0 100644
--- a/sql/password.c
+++ b/sql/password.c
@@ -48,6 +48,8 @@
   This authentication needs 2 packet round trips instead of one but it is much 
   stronger. Now if one will steal mysql database content he will not be able 
   to break into MySQL.
+
+  New Password handling functions by Peter Zaitsev
   
   
 *****************************************************************************/
diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index d4ca8ed1bc7..3ebd3fdbd3b 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -33,52 +33,6 @@
 #include <stdarg.h>
 
 
-struct acl_host_and_ip
-{
-  char *hostname;
-  long ip,ip_mask;			// Used with masked ip:s
-};
-
-
-class ACL_ACCESS {
-public:
-  ulong sort;
-  ulong access;
-};
-
-
-/* ACL_HOST is used if no host is specified */
-
-class ACL_HOST :public ACL_ACCESS
-{
-public:
-  acl_host_and_ip host;
-  char *db;
-};
-
-
-class ACL_USER :public ACL_ACCESS
-{
-public:
-  acl_host_and_ip host;
-  uint hostname_length;
-  USER_RESOURCES user_resource;
-  char *user,*password;
-  ulong salt[6]; // New password has longer length
-  uint8 pversion; // password version 
-  enum SSL_type ssl_type;
-  const char *ssl_cipher, *x509_issuer, *x509_subject;
-};
-
-
-class ACL_DB :public ACL_ACCESS
-{
-public:
-  acl_host_and_ip host;
-  char *user,*db;
-};
-
-
 class acl_entry :public hash_filo_element
 {
 public:
@@ -105,6 +59,7 @@ static HASH acl_check_hosts, hash_tables;
 static DYNAMIC_ARRAY acl_wild_hosts;
 static hash_filo *acl_cache;
 static uint grant_version=0;
+static uint priv_version=0; /* Version of priv tables. incremented by acl_init */
 static ulong get_access(TABLE *form,uint fieldnr);
 static int acl_compare(ACL_ACCESS *a,ACL_ACCESS *b);
 static ulong get_sort(uint count,...);
@@ -148,7 +103,9 @@ my_bool acl_init(THD *org_thd, bool dont_read_acl_tables)
   {
     DBUG_RETURN(0); /* purecov: tested */
   }    
-
+  
+  priv_version++; /* Priveleges updated */
+  
   /*
     To be able to run this from boot, we allocate a temporary THD
   */
@@ -515,15 +472,23 @@ void prepare_scramble(THD* thd, ACL_USER *acl_user,char* prepared_scramble)
 /*
   Get master privilges for user (priviliges for all tables).
   Required before connecting to MySQL
+  
+  as we have 2 stage handshake now we cache user not to lookup
+  it second time. At the second stage we do not lookup user in case 
+  we already know it;
+  
 */
 
 ulong acl_getroot(THD *thd, const char *host, const char *ip, const char *user,
 		  const char *password,const char *message,char **priv_user,
-		  bool old_ver, USER_RESOURCES  *mqh,char* prepared_scramble,int stage)
+		  bool old_ver, USER_RESOURCES  *mqh,char* prepared_scramble,
+                  int stage,uint *cur_priv_version,ACL_USER** hint_user)
 {
   ulong user_access=NO_ACCESS;
   *priv_user=(char*) user;
   bool password_correct=0;
+  ACL_USER *acl_user=NULL;
+  
   DBUG_ENTER("acl_getroot");
 
   bzero(mqh,sizeof(USER_RESOURCES));
@@ -533,159 +498,175 @@ ulong acl_getroot(THD *thd, const char *host, const char *ip, const char *user,
     DBUG_RETURN((ulong) ~NO_ACCESS);		/* purecov: tested */
   }
   VOID(pthread_mutex_lock(&acl_cache->lock));
-
+  
+  
   /*
     Get possible access from user_list. This is or'ed to others not
     fully specified
+    
+    If we have cached user use it, in other case look it up.
   */
-  for (uint i=0 ; i < acl_users.elements ; i++)
-  {
-    ACL_USER *acl_user=dynamic_element(&acl_users,i,ACL_USER*);
-    if (!acl_user->user || !strcmp(user,acl_user->user))
+  
+  if (stage && (*cur_priv_version==priv_version))
+    acl_user=*hint_user;
+  else  
+    for (uint i=0 ; i < acl_users.elements ; i++)
     {
-      if (compare_hostname(&acl_user->host,host,ip))
+      ACL_USER *acl_user_search=dynamic_element(&acl_users,i,ACL_USER*);
+      if (!acl_user_search->user || !strcmp(user,acl_user_search->user))
       {
-	if (!acl_user->password && !*password ||
-	    (acl_user->password && *password))
-        {    
-          /* Quick check and accept for empty passwords*/
-          if (!acl_user->password && !*password)
-            password_correct=1;
-          else
-          {    
-            /* New version password is checked differently */
-            if (acl_user->pversion)
-            {
-              if (stage) /* We check password only on the second stage */
-              {
-                if (!validate_password(password,message,acl_user->salt))
-                  password_correct=1;
-              }      
-              else  /* First stage - just prepare scramble */
-                prepare_scramble(thd,acl_user,prepared_scramble);
-            }
-            /* Old way to check password */
-            else 
-            {
-              /* Checking the scramble at any stage. First - old clients */ 
-              if (!check_scramble(password,message,acl_user->salt,
-	                          (my_bool) old_ver))
-                password_correct=1;
-              else /* Password incorrect  */  
-                /* At the first stage - prepare scramble */
-                if (!stage)
-                  prepare_scramble(thd,acl_user,prepared_scramble);                 
-            }    
+        if (compare_hostname(&acl_user_search->host,host,ip))
+        {
+          /* Found mathing user */ 
+          acl_user=acl_user_search;
+          /* Store it as a cache */
+          *hint_user=acl_user;
+          *cur_priv_version=priv_version;
+          break;
+        }  
+      }
+    } 
+    
+  
+  /* Now we have acl_user found and may start our checks */
+  
+  if (acl_user)      
+  { 
+    /* Password should present for both or absend for both */       
+    if (!acl_user->password && !*password ||
+       (acl_user->password && *password))
+    {    
+      /* Quick check and accept for empty passwords*/
+      if (!acl_user->password && !*password)
+        password_correct=1;
+      else /* Normal password presents */
+      {    
+        /* New version password is checked differently */
+        if (acl_user->pversion)
+        {
+          if (stage) /* We check password only on the second stage */
+          {
+            if (!validate_password(password,message,acl_user->salt))
+              password_correct=1;
           }      
-          /* If password correct continue with checking other limitations */          
-          if (password_correct)                     
-	  {
-#ifdef HAVE_OPENSSL
-	    Vio *vio=thd->net.vio;
-            /*
-	      In this point we know that user is allowed to connect 
-	      from given host by given username/password pair. Now 
-	      we check if SSL is required, if user is using SSL and 
-	      if X509 certificate attributes are OK 
-	    */
-            switch (acl_user->ssl_type) {
-	    case SSL_TYPE_NOT_SPECIFIED:		// Impossible
-            case SSL_TYPE_NONE: /* SSL is not required to connect */
-	      user_access=acl_user->access;
-	      break;
-	    case SSL_TYPE_ANY: /* Any kind of SSL is good enough */
-	      if (vio_type(vio) == VIO_TYPE_SSL)
-	        user_access=acl_user->access;
-	      break;
-	    case SSL_TYPE_X509: /* Client should have any valid certificate. */
-	      /*
-	        Connections with non-valid certificates are dropped already 
-	        in sslaccept() anyway, so we do not check validity here. 
-	      */
-	      if (SSL_get_peer_certificate(vio->ssl_))
-	        user_access=acl_user->access;
-	      break;
-	    case SSL_TYPE_SPECIFIED: /* Client should have specified attrib */
-	      /*
-	        We do not check for absence of SSL because without SSL it does
-	        not pass all checks here anyway.
-	        If cipher name is specified, we compare it to actual cipher in
-	        use.
-	      */
-	      if (acl_user->ssl_cipher)
-	      {
-	        DBUG_PRINT("info",("comparing ciphers: '%s' and '%s'",
-	  			 acl_user->ssl_cipher,
-	  			 SSL_get_cipher(vio->ssl_)));
-	        if (!strcmp(acl_user->ssl_cipher,SSL_get_cipher(vio->ssl_)))
-	          user_access=acl_user->access;
-	        else
-	        {
-		  user_access=NO_ACCESS;
-	          break;
-	        }
-	      }
-	      /* Prepare certificate (if exists) */
-	      DBUG_PRINT("info",("checkpoint 1"));
-	      X509* cert=SSL_get_peer_certificate(vio->ssl_);
-	      DBUG_PRINT("info",("checkpoint 2"));
-	      /* If X509 issuer is speified, we check it... */
-	      if (acl_user->x509_issuer) 
-	      {
-	        DBUG_PRINT("info",("checkpoint 3"));
-	        char *ptr = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
-	        DBUG_PRINT("info",("comparing issuers: '%s' and '%s'",
-				 acl_user->x509_issuer, ptr));
-	        if (strcmp(acl_user->x509_issuer, ptr))
-	        {
-		  user_access=NO_ACCESS;
-		  free(ptr);
-		  break;
-	        }
-	        user_access=acl_user->access;
-	        free(ptr);
-	      }
-	      DBUG_PRINT("info",("checkpoint 4"));
-	      /* X509 subject is specified, we check it .. */
-	      if (acl_user->x509_subject)
-	      {
-	        char *ptr= X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
-	        DBUG_PRINT("info",("comparing subjects: '%s' and '%s'",
-				 acl_user->x509_subject, ptr));
-	        if (strcmp(acl_user->x509_subject,ptr))
-	  	  user_access=NO_ACCESS;
-	        else
-		  user_access=acl_user->access;
-	        free(ptr);
-	      }
-	      break;
-	    }
-#else  /* HAVE_OPENSSL */
-	    user_access=acl_user->access;
-#endif /* HAVE_OPENSSL */
-	    *mqh=acl_user->user_resource;
-	    if (!acl_user->user)
-	    *priv_user=(char*) "";	// Change to anonymous user /* purecov: inspected */
-	    break;
-	  } // correct password
-        } // found matching user
+          else  /* First stage - just prepare scramble */
+            prepare_scramble(thd,acl_user,prepared_scramble);
+        }
+        /* Old way to check password */
+        else 
+        {
+          /* Checking the scramble at any stage. First - old clients */ 
+          if (!check_scramble(password,message,acl_user->salt,
+	       (my_bool) old_ver))
+            password_correct=1;
+           else /* Password incorrect  */  
+             /* At the first stage - prepare scramble */
+            if (!stage)
+              prepare_scramble(thd,acl_user,prepared_scramble);                 
+        }    
+      }
+    }
+  }
+  
+  /* If user not found password_correct will also be zero */
+  if (!password_correct)           
+   goto unlock_and_exit; 
+  
+  /* OK. User found and password checked continue validation */
+  
             
-#ifndef ALLOW_DOWNGRADE_OF_USERS
-	break;				// Wrong password breaks loop /* purecov: inspected */
-#endif
+#ifdef HAVE_OPENSSL
+  Vio *vio=thd->net.vio;
+  /*
+    In this point we know that user is allowed to connect 
+    from given host by given username/password pair. Now 
+    we check if SSL is required, if user is using SSL and 
+    if X509 certificate attributes are OK 
+  */
+  switch (acl_user->ssl_type) {
+  case SSL_TYPE_NOT_SPECIFIED:		// Impossible
+  case SSL_TYPE_NONE: /* SSL is not required to connect */
+    user_access=acl_user->access;
+    break;
+  case SSL_TYPE_ANY: /* Any kind of SSL is good enough */
+    if (vio_type(vio) == VIO_TYPE_SSL)
+    user_access=acl_user->access;
+    break;
+  case SSL_TYPE_X509: /* Client should have any valid certificate. */
+  /*
+    Connections with non-valid certificates are dropped already 
+    in sslaccept() anyway, so we do not check validity here. 
+  */
+    if (SSL_get_peer_certificate(vio->ssl_))
+      user_access=acl_user->access;
+    break;
+  case SSL_TYPE_SPECIFIED: /* Client should have specified attrib */
+  /*
+    We do not check for absence of SSL because without SSL it does
+    not pass all checks here anyway.
+    If cipher name is specified, we compare it to actual cipher in
+    use.
+  */
+    if (acl_user->ssl_cipher)
+    {
+      DBUG_PRINT("info",("comparing ciphers: '%s' and '%s'",
+        	 acl_user->ssl_cipher,SSL_get_cipher(vio->ssl_)));
+      if (!strcmp(acl_user->ssl_cipher,SSL_get_cipher(vio->ssl_)))
+        user_access=acl_user->access;
+      else
+      {
+        user_access=NO_ACCESS;
+        break;
+      }
+    }
+    /* Prepare certificate (if exists) */
+    DBUG_PRINT("info",("checkpoint 1"));
+    X509* cert=SSL_get_peer_certificate(vio->ssl_);
+    DBUG_PRINT("info",("checkpoint 2"));
+    /* If X509 issuer is speified, we check it... */
+    if (acl_user->x509_issuer) 
+    {
+      DBUG_PRINT("info",("checkpoint 3"));
+      char *ptr = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
+      DBUG_PRINT("info",("comparing issuers: '%s' and '%s'",
+    		 acl_user->x509_issuer, ptr));
+      if (strcmp(acl_user->x509_issuer, ptr))
+      {
+        user_access=NO_ACCESS;
+        free(ptr);
+        break;
       }
+      user_access=acl_user->access;
+      free(ptr);
+    }
+    DBUG_PRINT("info",("checkpoint 4"));
+    /* X509 subject is specified, we check it .. */
+    if (acl_user->x509_subject)
+    {
+      char *ptr= X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
+      DBUG_PRINT("info",("comparing subjects: '%s' and '%s'",
+		 acl_user->x509_subject, ptr));
+      if (strcmp(acl_user->x509_subject,ptr))
+        user_access=NO_ACCESS;
+      else
+        user_access=acl_user->access;
+      free(ptr);
     }
+    break;
   }
+#else  /* HAVE_OPENSSL */
+  user_access=acl_user->access;
+#endif /* HAVE_OPENSSL */
+  *mqh=acl_user->user_resource;
+  if (!acl_user->user)
+    *priv_user=(char*) "";	// Change to anonymous user /* purecov: inspected */
+    
+unlock_and_exit:
   VOID(pthread_mutex_unlock(&acl_cache->lock));
   DBUG_RETURN(user_access);
 }
 
 
-/*
-** Functions to add and change user and database privileges when one
-** changes things with GRANT
-*/
-
 static byte* check_get_key(ACL_USER *buff,uint *length,
 			   my_bool not_used __attribute__((unused)))
 {
diff --git a/sql/sql_acl.h b/sql/sql_acl.h
index 66e7d0dad7c..cfab9bf22cf 100644
--- a/sql/sql_acl.h
+++ b/sql/sql_acl.h
@@ -79,6 +79,55 @@
 #define fix_rights_for_column(A) (((A) & COL_ACLS) | ((A & ~COL_ACLS) << 7))
 #define get_rights_for_column(A) (((A) & COL_ACLS) | ((A & ~COL_ACLS) >> 7))
 
+/* Classes */
+
+struct acl_host_and_ip
+{
+  char *hostname;
+  long ip,ip_mask;                      // Used with masked ip:s
+};
+
+
+class ACL_ACCESS {
+public:
+  ulong sort;
+  ulong access;
+};
+
+
+/* ACL_HOST is used if no host is specified */
+
+class ACL_HOST :public ACL_ACCESS
+{
+public:
+  acl_host_and_ip host;
+  char *db;
+};
+
+
+class ACL_USER :public ACL_ACCESS
+{
+public:
+  acl_host_and_ip host;
+  uint hostname_length;
+  USER_RESOURCES user_resource;
+  char *user,*password;
+  ulong salt[6]; // New password has longer length
+  uint8 pversion; // password version
+  enum SSL_type ssl_type;
+  const char *ssl_cipher, *x509_issuer, *x509_subject;
+};
+
+
+class ACL_DB :public ACL_ACCESS
+{
+public:
+  acl_host_and_ip host;
+  char *user,*db;
+};
+
+
+
 /* prototypes */
 
 my_bool  acl_init(THD *thd, bool dont_read_acl_tables);
@@ -88,7 +137,8 @@ ulong acl_get(const char *host, const char *ip, const char *bin_ip,
 	      const char *user, const char *db);
 ulong acl_getroot(THD *thd, const char *host, const char *ip, const char *user,
 		  const char *password,const char *scramble,char **priv_user,
-		  bool old_ver, USER_RESOURCES *max,char* prepared_scramble, int stage);
+		  bool old_ver, USER_RESOURCES *max,char* prepared_scramble,
+                  int stage, uint *cur_priv_version, ACL_USER **cached_user);
 bool acl_check_host(const char *host, const char *ip);
 bool check_change_password(THD *thd, const char *host, const char *user);
 bool change_password(THD *thd, const char *host, const char *user,
diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc
index 48a02b56c0b..bdb074b304d 100644
--- a/sql/sql_parse.cc
+++ b/sql/sql_parse.cc
@@ -188,14 +188,16 @@ end:
   thd->user, thd->master_access, thd->priv_user, thd->db, thd->db_access
 */
 
-static bool check_user(THD *thd,enum_server_command command, const char *user,
+static int check_user(THD *thd,enum_server_command command, const char *user,
 		       const char *passwd, const char *db, bool check_count, 
                        bool do_send_error, char* crypted_scramble,int stage,
-                       bool had_password)
+                       bool had_password,uint *cur_priv_version, 
+                       ACL_USER** hint_user)
 {
   thd->db=0;
   thd->db_length=0;
   USER_RESOURCES ur;
+  
   /* We shall avoid dupplicate user allocations here */ 
   if (!(thd->user))
     if (!(thd->user = my_strdup(user, MYF(0))))
@@ -207,7 +209,9 @@ static bool check_user(THD *thd,enum_server_command command, const char *user,
 				 passwd, thd->scramble, &thd->priv_user,
 				 protocol_version == 9 ||
 				 !(thd->client_capabilities &
-				   CLIENT_LONG_PASSWORD),&ur,crypted_scramble,stage);
+				   CLIENT_LONG_PASSWORD),&ur,crypted_scramble,
+                                   stage,cur_priv_version,hint_user);
+                                   
   DBUG_PRINT("info",
 	     ("Capabilities: %d  packet_length: %d  Host: '%s'  User: '%s'  Using password: %s  Access: %u  db: '%s'",
 	      thd->client_capabilities, thd->max_client_packet_length,
@@ -233,7 +237,7 @@ static bool check_user(THD *thd,enum_server_command command, const char *user,
     else     
       return(-1); // do not report error in special handshake
   }
-      
+  
   if (check_count)
   {
     VOID(pthread_mutex_lock(&LOCK_thread_count));
@@ -261,12 +265,13 @@ static bool check_user(THD *thd,enum_server_command command, const char *user,
   if (thd->user_connect && thd->user_connect->user_resources.connections && 
       check_for_max_user_connections(thd, thd->user_connect))
     return -1;
+ 
   if (db && db[0])
   {
     bool error=test(mysql_change_db(thd,db));
     if (error && thd->user_connect)
       decrease_user_connections(thd->user_connect);
-    return error;
+    return error;    
   }
   else
     send_ok(thd);				// Ready to handle questions
@@ -616,7 +621,7 @@ check_connections(THD *thd)
   /* We can get only old hash at this point */
   if (passwd[0] && strlen(passwd)!=SCRAMBLE_LENGTH) 
       return ER_HANDSHAKE_ERROR;
-
+      
   if (thd->client_capabilities & CLIENT_INTERACTIVE)
      thd->variables.net_wait_timeout= thd->variables.net_interactive_timeout;
   if ((thd->client_capabilities & CLIENT_TRANSACTIONS) &&
@@ -625,6 +630,9 @@ check_connections(THD *thd)
   net->read_timeout=(uint) thd->variables.net_read_timeout;
     
   char prepared_scramble[SCRAMBLE41_LENGTH+4]; /* Buffer for scramble and hash */
+  
+  ACL_USER* cached_user;
+  uint cur_priv_version;
    
   /* Simple connect only for old clients. New clients always use secure auth */
   bool simple_connect=(!(thd->client_capabilities & CLIENT_SECURE_CONNECTION));
@@ -634,7 +642,7 @@ check_connections(THD *thd)
   
   /* Check user permissions. If password failure we'll get scramble back */
   if (check_user(thd,COM_CONNECT, user, passwd, db, 1, simple_connect,
-      prepared_scramble,0,using_password))
+      prepared_scramble,0,using_password,&cur_priv_version,&cached_user)<0)
   { 
     /* If The client is old we just have to return error */
     if (simple_connect)
@@ -682,7 +690,8 @@ check_connections(THD *thd)
       }
     /* Final attempt to check the user based on reply */ 
     if (check_user(thd,COM_CONNECT, tmp_user, (char*)net->read_pos, 
-        tmp_db, 1, 1,prepared_scramble,1,using_password))
+        tmp_db, 1, 1,prepared_scramble,1,using_password,&cur_priv_version,
+        &cached_user))
       return -1;
   }
   thd->password=using_password;
@@ -1034,43 +1043,117 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
     char *user=   (char*) packet;
     char *passwd= strend(user)+1;
     char *db=     strend(passwd)+1;
-
+    
     /* Save user and privileges */
     uint save_master_access=thd->master_access;
     uint save_db_access=    thd->db_access;
     uint save_db_length=    thd->db_length;
     char *save_user=	    thd->user;
+    thd->user=NULL; /* Needed for check_user to allocate new user */
     char *save_priv_user=   thd->priv_user;
     char *save_db=	    thd->db;
-    USER_CONN *save_uc=            thd->user_connect;
+    USER_CONN *save_uc=     thd->user_connect;
+    bool simple_connect;
+    bool using_password;
+    
+    ulong pkt_len=0; /* Length of reply packet */
+    
+    /* Small check for incomming packet */
 
     if ((uint) ((uchar*) db - net->read_pos) > packet_length)
-    {						// Check if protocol is ok
-      send_error(thd, ER_UNKNOWN_COM_ERROR);
-      break;
-    }
-    /* WARNING THIS HAS TO BE REWRITTEN */
-    char tmp_buffer[64];
-    printf("Change user called: %s %s %s\n",user,passwd,db);
-    if (check_user(thd, COM_CHANGE_USER, user, passwd, db, 0,1,tmp_buffer,0,1))
-    {						// Restore old user
-      x_free(thd->user);
-      x_free(thd->db);
-      thd->master_access=save_master_access;
-      thd->db_access=save_db_access;
-      thd->db=save_db;
-      thd->db_length=save_db_length;
-      thd->user=save_user;
-      thd->priv_user=save_priv_user;
-      break;
+      goto restore_user_err;
+    
+    /* Now we shall basically perform authentication again */
+    
+     /* We can get only old hash at this point */
+    if (passwd[0] && strlen(passwd)!=SCRAMBLE_LENGTH) 
+      goto restore_user_err;
+      
+    char prepared_scramble[SCRAMBLE41_LENGTH+4];/* Buffer for scramble,hash */  
+    ACL_USER* cached_user;                      /* Cached user */
+    uint cur_priv_version;                      /* Cached grant version */
+   
+    /* Simple connect only for old clients. New clients always use sec. auth*/
+    simple_connect=(!(thd->client_capabilities & CLIENT_SECURE_CONNECTION));
+  
+    /* Store information if we used password. passwd will be dammaged */
+    using_password=test(passwd[0]);
+    
+    /* 
+     Check user permissions. If password failure we'll get scramble back 
+     Do not retry if we already have sent error (result>0) 
+    */ 
+    if (check_user(thd,COM_CHANGE_USER, user, passwd, db, 0, simple_connect,
+        prepared_scramble,0,using_password,&cur_priv_version,&cached_user)<0) 
+    {
+      /* If The client is old we just have to have auth failure */
+      if (simple_connect)
+        goto restore_user; /* Error is already reported */
+          
+      /* Store current used and database as they are erased with next packet */
+    
+      char tmp_user[USERNAME_LENGTH+1];
+      char tmp_db[NAME_LEN+1];
+
+      if (user)
+      {
+        strncpy(tmp_user,user,USERNAME_LENGTH+1);
+        /* Extra safety if we have too long data */
+        tmp_user[USERNAME_LENGTH]=0;   
+      } 
+      else
+        tmp_user[0]=0;  
+      if (db)
+      {
+        strncpy(tmp_db,db,NAME_LEN+1);
+        tmp_db[NAME_LEN]=0;
+      }  
+      else 
+        tmp_db[0]=0;
+        
+      /* Write hash and encrypted scramble to client */
+      if (my_net_write(net,prepared_scramble,SCRAMBLE41_LENGTH+4) 
+        || net_flush(net))                      
+        goto restore_user_err;    
+        
+      /* Reading packet back */  
+      if ((pkt_len=my_net_read(net)) == packet_error)     
+        goto restore_user_err;
+      
+      /* We have to get very specific packet size  */  
+      if (pkt_len!=SCRAMBLE41_LENGTH) 
+        goto restore_user;
+      
+      /* Final attempt to check the user based on reply */ 
+      if (check_user(thd,COM_CONNECT, tmp_user, (char*)net->read_pos, 
+          tmp_db, 0, 1,prepared_scramble,1,using_password,&cur_priv_version,
+          &cached_user))
+        goto restore_user;
     }
+    /* Finally we've authenticated new user */
     if (max_connections && save_uc)
       decrease_user_connections(save_uc);
     x_free((gptr) save_db);
     x_free((gptr) save_user);
-    thd->password=test(passwd[0]);
+    thd->password=using_password;
+    break;
+    
+    /* Bad luck  we shall restore old user */
+    restore_user_err:
+    send_error(thd, ER_UNKNOWN_COM_ERROR);
+    
+    restore_user:
+    x_free(thd->user);
+    x_free(thd->db);
+    thd->master_access=save_master_access;
+    thd->db_access=save_db_access;
+    thd->db=save_db;
+    thd->db_length=save_db_length;
+    thd->user=save_user;
+    thd->priv_user=save_priv_user;    
     break;
   }
+  
   case COM_EXECUTE:
   {
     mysql_stmt_execute(thd, packet);