Style fixes, comments for 4.1.1 authorization

Now special 1-byte packet is used for request of old password
Fixed bug with --skip-grant-tables and acl_getroot

include/mysql.h

@@ -228,8 +228,8 @@ typedef struct st_mysql
   my_bool	free_me;		/* If free in mysql_close */
   my_bool	reconnect;		/* set to 1 if automatic reconnect */
 
-  char	        scramble[SCRAMBLE_LENGTH+1]; /* for new servers */
+  /* session-wide random string */
-  char          scramble_323[SCRAMBLE_LENGTH_323+1]; /* for old servers */
+  char	        scramble[max(SCRAMBLE_LENGTH,SCRAMBLE_LENGTH_323)+1];
 
  /*
    Set if this is the original connection, not a master or a slave we have

include/mysql_com.h

@@ -318,9 +318,9 @@ void randominit(struct rand_struct *, unsigned long seed1,
 double my_rnd(struct rand_struct *);
 void create_random_string(char *to, uint length, struct rand_struct *rand_st);
 
-void hash_password(ulong *to, const char *password);
+void hash_password(ulong *to, const char *password, uint password_len);
 void make_scrambled_password_323(char *to, const char *password);
-char *scramble_323(char *to, const char *message, const char *password);
+void scramble_323(char *to, const char *message, const char *password);
 my_bool check_scramble_323(const char *, const char *message,
                            unsigned long *salt);
 void get_salt_from_password_323(unsigned long *res, const char *password);

libmysql/libmysql.c

@@ -626,7 +626,10 @@ my_bool	STDCALL mysql_change_user(MYSQL *mysql, const char *user,
       end+= SCRAMBLE_LENGTH;
     }
     else
-      end= scramble_323(end, mysql->scramble_323, passwd);
+    {
+      scramble_323(end, mysql->scramble, passwd);
+      end+= SCRAMBLE_LENGTH_323 + 1;
+    }
   }
   else
     *end++= '\0';                               // empty password
@@ -642,15 +645,14 @@ my_bool	STDCALL mysql_change_user(MYSQL *mysql, const char *user,
   if (pkt_length == packet_error)
     goto error;
 
-  if (net->read_pos[0] == mysql->scramble_323[0] &&
+  if (pkt_length == 1 && net->read_pos[0] == 254 &&
-      pkt_length == SCRAMBLE_LENGTH_323 + 1 &&
       mysql->server_capabilities & CLIENT_SECURE_CONNECTION)
   {
     /*
       By sending this very specific reply server asks us to send scrambled
       password in old format. The reply contains scramble_323.
     */
-    scramble_323(buff, mysql->scramble_323, passwd);
+    scramble_323(buff, mysql->scramble, passwd);
     if (my_net_write(net, buff, SCRAMBLE_LENGTH_323 + 1) || net_flush(net))
     {
       net->last_errno= CR_SERVER_LOST;

sql-common/client.c

@@ -1641,9 +1641,8 @@ mysql_real_connect(MYSQL *mysql,const char *host, const char *user,
     Scramble is split into two parts because old clients does not understand
     long scrambles; here goes the first part.
   */
-  strmake(mysql->scramble_323, end, SCRAMBLE_LENGTH_323);
+  strmake(mysql->scramble, end, SCRAMBLE_LENGTH_323);
   end+= SCRAMBLE_LENGTH_323+1;
-  memcpy(mysql->scramble, mysql->scramble_323, SCRAMBLE_LENGTH_323);
 
   if (pkt_length >= (uint) (end+1 - (char*) net->read_pos))
     mysql->server_capabilities=uint2korr(end);
@@ -1842,7 +1841,10 @@ mysql_real_connect(MYSQL *mysql,const char *host, const char *user,
       end+= SCRAMBLE_LENGTH;
     }
     else
-      end= scramble_323(end, mysql->scramble_323, passwd) + 1;
+    {
+      scramble_323(end, mysql->scramble, passwd);
+      end+= SCRAMBLE_LENGTH_323 + 1;
+    }
   }
   else
     *end++= '\0';                               /* empty password */
@@ -1871,15 +1873,14 @@ mysql_real_connect(MYSQL *mysql,const char *host, const char *user,
   if ((pkt_length=net_safe_read(mysql)) == packet_error)
     goto error;
 
-  if (net->read_pos[0] == mysql->scramble_323[0] &&
+  if (pkt_length == 1 && net->read_pos[0] == 254 && 
-      pkt_length == SCRAMBLE_LENGTH_323 + 1 &&
       mysql->server_capabilities & CLIENT_SECURE_CONNECTION)
   {
     /*
       By sending this very specific reply server asks us to send scrambled
       password in old format. The reply contains scramble_323.
     */
-    scramble_323(buff, mysql->scramble_323, passwd);
+    scramble_323(buff, mysql->scramble, passwd);
     if (my_net_write(net, buff, SCRAMBLE_LENGTH_323 + 1) || net_flush(net))
     {
       net->last_errno= CR_SERVER_LOST;

sql/password.c

@@ -110,15 +110,17 @@ double my_rnd(struct rand_struct *rand_st)
     Used for Pre-4.1 password handling
   SYNOPSIS
     hash_password()
-    result    OUT store hash in this location
+    result       OUT store hash in this location
-    password  IN  plain text password to build hash
+    password     IN  plain text password to build hash
+    password_len IN  password length (password may be not null-terminated)
 */
 
-void hash_password(ulong *result, const char *password)
+void hash_password(ulong *result, const char *password, uint password_len)
 {
   register ulong nr=1345345333L, add=7, nr2=0x12345671L;
   ulong tmp;
-  for (; *password ; password++)
+  const char *password_end= password + password_len;
+  for (; password < password_end; password++)
   {
     if (*password == ' ' || *password == '\t')
       continue;                                 /* skip space in password */
@@ -129,7 +131,6 @@ void hash_password(ulong *result, const char *password)
   }
   result[0]=nr & (((ulong) 1L << 31) -1L); /* Don't use sign bit (str2int) */;
   result[1]=nr2 & (((ulong) 1L << 31) -1L);
-  return;
 }
 
 
@@ -145,7 +146,7 @@ void hash_password(ulong *result, const char *password)
 void make_scrambled_password_323(char *to, const char *password)
 {
   ulong hash_res[2];
-  hash_password(hash_res, password);
+  hash_password(hash_res, password, strlen(password));
   sprintf(to, "%08lx%08lx", hash_res[0], hash_res[1]);
 }
 
@@ -157,14 +158,12 @@ void make_scrambled_password_323(char *to, const char *password)
     scramble_323()
     to       OUT Store scrambled message here. Buffer must be at least
                  SCRAMBLE_LENGTH_323+1 bytes long
-    message  IN  Message to scramble. Message must be exactly 
+    message  IN  Message to scramble. Message must be at least
-                 SRAMBLE_LENGTH_323 long and NULL terminated. 
+                 SRAMBLE_LENGTH_323 bytes long.
     password IN  Password to use while scrambling
-  RETURN
-    End of scrambled string
 */
 
-char *scramble_323(char *to, const char *message, const char *password)
+void scramble_323(char *to, const char *message, const char *password)
 {
   struct rand_struct rand_st;
   ulong hash_pass[2], hash_message[2];
@@ -172,18 +171,18 @@ char *scramble_323(char *to, const char *message, const char *password)
   if (password && password[0])
   {
     char *to_start=to;
-    hash_password(hash_pass,password);
+    hash_password(hash_pass,password, strlen(password));
-    hash_password(hash_message, message);
+    hash_password(hash_message, message, SCRAMBLE_LENGTH_323);
     randominit(&rand_st,hash_pass[0] ^ hash_message[0],
                hash_pass[1] ^ hash_message[1]);
-    while (*message++)
+    const char *message_end= message + SCRAMBLE_LENGTH_323;
+    for (; message < message_end; message++)
       *to++= (char) (floor(my_rnd(&rand_st)*31)+64);
     char extra=(char) (floor(my_rnd(&rand_st)*31));
     while (to_start != to)
       *(to_start++)^=extra;
   }
   *to= 0;
-  return to;
 }
 
 
@@ -192,11 +191,13 @@ char *scramble_323(char *to, const char *message, const char *password)
     Used in pre 4.1 password handling
   SYNOPSIS
     check_scramble_323()
-    scrambled  IN scrambled message to check.
+    scrambled  scrambled message to check.
-    message    IN original random message which was used for scrambling; must
+    message    original random message which was used for scrambling; must
-                  be exactly SCRAMBLED_LENGTH_323 bytes long and
+               be exactly SCRAMBLED_LENGTH_323 bytes long and
-                  NULL-terminated.
+               NULL-terminated.
-    hash_pass  IN password which should be used for scrambling
+    hash_pass  password which should be used for scrambling
+    All params are IN.
+
   RETURN VALUE
     0 - password correct
    !0 - password invalid
@@ -211,11 +212,7 @@ check_scramble_323(const char *scrambled, const char *message,
   char buff[16],*to,extra;                      /* Big enough for check */
   const char *pos;
   
-  /* Check if this exactly N bytes. Overwise this is something fishy */
+  hash_password(hash_message, message, SCRAMBLE_LENGTH_323);
-  if (strlen(message) != SCRAMBLE_LENGTH_323)
-    return 1;                                   /* Wrong password */
-
-  hash_password(hash_message,message);
   randominit(&rand_st,hash_pass[0] ^ hash_message[0],
              hash_pass[1] ^ hash_message[1]);
   to=buff;
@@ -231,7 +228,7 @@ check_scramble_323(const char *scrambled, const char *message,
   return 0;
 }
 
-static uint8 char_val(uint8 X)
+static inline uint8 char_val(uint8 X)
 {
   return (uint) (X >= '0' && X <= '9' ? X-'0' :
       X >= 'A' && X <= 'Z' ? X-'A'+10 : X-'a'+10);
@@ -280,7 +277,10 @@ void make_password_from_salt_323(char *to, const ulong *salt)
 }
 
 
-/******************* MySQL 4.1.1 authentification routines ******************/
+/*
+     **************** MySQL 4.1.1 authentification routines *************
+*/
+
 /*
     Generate string of printable random characters of requested length
   SYNOPSIS
@@ -315,19 +315,16 @@ void create_random_string(char *to, uint length, struct rand_struct *rand_st)
     str, len  IN  the beginning and the length of the input string
 */
 
-static
+static void
-void
 octet2hex(char *to, const uint8 *str, uint len)
 {
-  static const char alphabet[] = { '0', '1', '2', '3', '4', '5', '6', '7',
-                                   '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
   const uint8 *str_end= str + len; 
   for (; str != str_end; ++str)
   {
-    *to++= alphabet[(*str & 0xF0) >> 4];
+    *to++= _dig_vec[(*str & 0xF0) >> 4];
-    *to++= alphabet[*str & 0x0F];
+    *to++= _dig_vec[*str & 0x0F];
   }
-  *to++= '\0';
+  *to= '\0';
 }
 
 
@@ -341,15 +338,14 @@ octet2hex(char *to, const uint8 *str, uint len)
                   overlap; len % 2 == 0
 */ 
 
-static
+static void
-void
 hex2octet(uint8 *to, const char *str, uint len)
 {
   const char *str_end= str + len;
   while (str < str_end)
   {
-    *to= char_val(*str++) << 4;
+    register char tmp= char_val(*str++);
-    *to++|= char_val(*str++);
+    *to++= (tmp << 4) | char_val(*str++);
   }
 }
 
@@ -366,9 +362,8 @@ hex2octet(uint8 *to, const char *str, uint len)
     len     IN  length of s1 and s2
 */
 
-static
+static void
-void
+my_crypt(char *to, const uchar *s1, const uchar *s2, uint len)
-my_crypt(char *to, const uint8 *s1, const uint8 *s2, uint len)
 {
   const uint8 *s1_end= s1 + len;
   while (s1 < s1_end)
@@ -447,7 +442,7 @@ scramble(char *to, const char *message, const char *password)
   sha1_input(&sha1_context, hash_stage2, SHA1_HASH_SIZE);
   /* xor allows 'from' and 'to' overlap: lets take advantage of it */
   sha1_result(&sha1_context, (uint8 *) to);
-  my_crypt(to, (const uint8 *) to, hash_stage1, SCRAMBLE_LENGTH);
+  my_crypt(to, (const uchar *) to, hash_stage1, SCRAMBLE_LENGTH);
 }
 
 
@@ -459,11 +454,13 @@ scramble(char *to, const char *message, const char *password)
     long (if not, something fishy is going on).
   SYNOPSIS
     check_scramble()
-    scramble     IN clients' reply, presumably produced by scramble()
+    scramble     clients' reply, presumably produced by scramble()
-    message      IN original random string, previously sent to client
+    message      original random string, previously sent to client
-                    (presumably second argument of scramble()), must be 
+                 (presumably second argument of scramble()), must be 
-                    exactly SCRAMBLE_LENGTH long and NULL-terminated.
+                 exactly SCRAMBLE_LENGTH long and NULL-terminated.
-    hash_stage2  IN hex2octet-decoded database entry
+    hash_stage2  hex2octet-decoded database entry
+    All params are IN.
+
   RETURN VALUE
     0  password is correct
     !0  password is invalid
@@ -483,7 +480,7 @@ check_scramble(const char *scramble, const char *message,
   sha1_input(&sha1_context, hash_stage2, SHA1_HASH_SIZE);
   sha1_result(&sha1_context, buf);
   /* encrypt scramble */
-  my_crypt((char *) buf, buf, (const uint8 *) scramble, SCRAMBLE_LENGTH);
+    my_crypt((char *) buf, buf, (const uchar *) scramble, SCRAMBLE_LENGTH);
   /* now buf supposedly contains hash_stage1: so we can get hash_stage2 */
   sha1_reset(&sha1_context);
   sha1_input(&sha1_context, buf, SHA1_HASH_SIZE);

sql/protocol.cc

@@ -348,6 +348,25 @@ send_eof(THD *thd, bool no_flush)
   }
   DBUG_VOID_RETURN;
 }
+
+/*
+    Please client to send scrambled_password in old format.
+  SYNOPSYS
+    send_old_password_request()
+    thd thread handle
+     
+  RETURN VALUE
+    0  ok
+   !0  error
+*/
+
+bool send_old_password_request(THD *thd)
+{
+  static char buff[1]= { (char) 254 };
+  NET *net= &thd->net;
+  return my_net_write(net, buff, 1) || net_flush(net);
+}
+
 #endif /* EMBEDDED_LIBRARY */
 
 

sql/protocol.h

@@ -164,6 +164,7 @@ void net_printf(THD *thd,uint sql_errno, ...);
 void send_ok(THD *thd, ha_rows affected_rows=0L, ulonglong id=0L,
 	     const char *info=0);
 void send_eof(THD *thd, bool no_flush=0);
+bool send_old_password_request(THD *thd);
 char *net_store_length(char *packet,ulonglong length);
 char *net_store_length(char *packet,uint length);
 char *net_store_data(char *to,const char *from, uint length);

sql/sql_acl.cc

@@ -264,10 +264,11 @@ my_bool acl_init(THD *org_thd, bool dont_read_acl_tables)
     {
       switch (password_len) {
       case 45: /* 4.1: to be removed */
-        sql_print_error("Found 4.1 style password for user '%s'. "
+        sql_print_error("Found 4.1 style password for user '%s@%s'. "
                         "Ignoring user. "
                         "You should change password for this user.",
-                        user.user ? user.user : "");
+                        user.user ? user.user : "",
+                        user.host.hostname ? user.host.hostname : "");
         break;
       default:
         sql_print_error("Found invalid password for user: '%s@%s'; "
@@ -526,23 +527,30 @@ static int acl_compare(ACL_ACCESS *a,ACL_ACCESS *b)
 /*
     Seek ACL entry for a user, check password, SSL cypher, and if
     everything is OK, update THD user data and USER_RESOURCES struct.
+
+ IMPLEMENTATION
     This function does not check if the user has any sensible privileges:
     only user's existence and  validity is checked.
     Note, that entire operation is protected by acl_cache_lock.
+
   SYNOPSIS
-    thd          INOUT thread handle. If all checks are OK,
+    acl_getroot()
-                       thd->priv_user, thd->master_access are updated.
+    thd         thread handle. If all checks are OK,
-                       thd->host, thd->ip, thd->user are used for checks.
+                thd->priv_user, thd->master_access are updated.
-    mqh          OUT   user resources; on success mqh is reset, else
+                thd->host, thd->ip, thd->user are used for checks.
-                       unchanged
+    mqh         user resources; on success mqh is reset, else
-    passwd       IN    scrambled & crypted password, recieved from client
+                unchanged
-                       (to check): thd->scramble or thd->scramble_323 is
+    passwd      scrambled & crypted password, recieved from client
-                       used to decrypt passwd, so they must contain
+                (to check): thd->scramble or thd->scramble_323 is
-                       original random string,
+                used to decrypt passwd, so they must contain
-    passwd_len   IN    length of passwd, must be one of 0, 8,
+                original random string,
-                       SCRAMBLE_LENGTH_323, SCRAMBLE_LENGTH
+    passwd_len  length of passwd, must be one of 0, 8,
+                SCRAMBLE_LENGTH_323, SCRAMBLE_LENGTH
+    'thd' and 'mqh' are updated on success; other params are IN.
+  
  RETURN VALUE
-    0  success: thread data and mqh are updated
+    0  success: thd->priv_user, thd->priv_host, thd->master_access, mqh are
+       updated
     1  user not found or authentification failure
     2  user found, has long (4.1.1) salt, but passwd is in old (3.23) format.
    -1  user found, has short (3.23) salt, but passwd is in new (4.1.1) format.
@@ -553,9 +561,16 @@ int acl_getroot(THD *thd, USER_RESOURCES  *mqh,
 {
   DBUG_ENTER("acl_getroot");
 
-  if (!initialized) /* if no data allow anything */
+  if (!initialized)
-  { 
+  {
-    DBUG_RETURN(1);
+    /* 
+      here if mysqld's been started with --skip-grant-tables option.
+    */
+    thd->priv_user= (char *) "";                // privileges for
+    *thd->priv_host= '\0';                      // the user are unknown
+    thd->master_access= ~NO_ACCESS;             // everything is allowed
+    bzero(mqh, sizeof(*mqh));
+    DBUG_RETURN(0);
   }
 
   int res= 1;
@@ -582,7 +597,7 @@ int acl_getroot(THD *thd, USER_RESOURCES  *mqh,
           if (user_i->salt_len == 0 ||
               user_i->salt_len == SCRAMBLE_LENGTH &&
               check_scramble(passwd, thd->scramble, user_i->salt) == 0 ||
-              check_scramble_323(passwd, thd->scramble_323,
+              check_scramble_323(passwd, thd->scramble,
                                  (ulong *) user_i->salt) == 0)
           {
             acl_user= user_i;
@@ -1346,8 +1361,7 @@ static int replace_user_table(THD *thd, TABLE *table, const LEX_USER &combo,
 {
   int error = -1;
   bool old_row_exists=0;
-  char empty_string[]= { '\0' };
+  const char *password= "";
-  char *password= empty_string;
   uint password_len= 0;
   char what= (revoke_grant) ? 'N' : 'Y';
   DBUG_ENTER("replace_user_table");

sql/sql_class.h

@@ -547,13 +547,7 @@ public:
   DYNAMIC_ARRAY user_var_events;
 
   /* scramble - random string sent to client on handshake */
-  char	     scramble[SCRAMBLE_LENGTH+1];
+  char	     scramble[max(SCRAMBLE_LENGTH, SCRAMBLE_LENGTH_323)+1];
-  /*
-    The same as scramble but for old password checking routines. It always
-    contains first N bytes of scramble.
-    See check_connection() at sql_parse.cc for authentification details.
-  */
-  char       scramble_323[SCRAMBLE_LENGTH_323+1];
 
   uint8	     query_cache_type;		// type of query cache processing
   bool       slave_thread;

sql/sql_crypt.cc

@@ -32,7 +32,7 @@
 SQL_CRYPT::SQL_CRYPT(const char *password)
 {
   ulong rand_nr[2];
-  hash_password(rand_nr,password);
+  hash_password(rand_nr,password, strlen(password));
   crypt_init(rand_nr);
 }
 

sql/sql_parse.cc

@@ -181,17 +181,20 @@ end:
     Check if user exist and password supplied is correct. 
   SYNOPSIS
     check_user()
-    thd          INOUT thread handle, thd->{host,user,ip} are used
+    thd          thread handle, thd->{host,user,ip} are used
-    command      IN    originator of the check: now check_user is called
+    command      originator of the check: now check_user is called
-                       during connect and change user procedures; used for 
+                 during connect and change user procedures; used for 
-                       logging.
+                 logging.
-    passwd       IN    scrambled password recieved from client
+    passwd       scrambled password recieved from client
-    passwd_len   IN    length of scrambled password
+    passwd_len   length of scrambled password
-    db           IN    database name to connect to, may be NULL
+    db           database name to connect to, may be NULL
-    check_count  IN    dont know exactly
+    check_count  dont know exactly
+
     Note, that host, user and passwd may point to communication buffer.
     Current implementation does not depened on that, but future changes
-    should be done with this in mind.
+    should be done with this in mind; 'thd' is INOUT, all other params
+    are 'IN'.
+
   RETURN VALUE
     0  OK; thd->user, thd->master_access, thd->priv_user, thd->db and
        thd->db_access are updated; OK is sent to client;
@@ -226,8 +229,10 @@ static int check_user(THD *thd, enum enum_server_command command,
     DBUG_RETURN(ER_HANDSHAKE_ERROR);
 
   /*
-    Why this is set here? - probably to reset current DB to 'no database
+    Clear thd->db as it points to something, that will be freed when 
-    selected' in case of 'change user' failure.
+    connection is closed. We don't want to accidently free a wrong pointer
+    if connect failed. Also in case of 'CHANGE USER' failure, current
+    database will be switched to 'no database selected'.
   */
   thd->db= 0;
   thd->db_length= 0;
@@ -244,6 +249,7 @@ static int check_user(THD *thd, enum enum_server_command command,
       scramble_323()). Here we please client to send scrambled_password
       in old format.
     */
+    NET *net= &thd->net;
     if (opt_secure_auth_local)
     {
       net_printf(thd, ER_SERVER_IS_IN_SECURE_AUTH_MODE,
@@ -258,9 +264,7 @@ static int check_user(THD *thd, enum enum_server_command command,
       strmake(buff, db, NAME_LEN);
       db= buff;
     }
-    NET *net= &thd->net;
+    if (send_old_password_request(thd) ||
-    if (my_net_write(net, thd->scramble_323, SCRAMBLE_LENGTH_323 + 1) ||
-        net_flush(net) ||
         my_net_read(net) != SCRAMBLE_LENGTH_323 + 1) // We have to read very
     {                                                // specific packet size
       inc_host_errors(&thd->remote.sin_addr);
@@ -288,7 +292,7 @@ static int check_user(THD *thd, enum enum_server_command command,
       {
         VOID(pthread_mutex_lock(&LOCK_thread_count));
         bool count_ok= thread_count < max_connections + delayed_insert_threads
-                       || thd->master_access & SUPER_ACL;
+                       || (thd->master_access & SUPER_ACL);
         VOID(pthread_mutex_unlock(&LOCK_thread_count));
         if (!count_ok)
         {                                         // too many connections 
@@ -305,7 +309,11 @@ static int check_user(THD *thd, enum enum_server_command command,
                       thd->user, thd->host_or_ip,
                       db ? db : (char*) "");
 
-      /* Why is it set here? */
+      /*
+        This is the default access rights for the current database.  It's
+        set to 0 here because we don't have an active database yet (and we
+        may not have an active database to set.
+      */
       thd->db_access=0;
 
       /* Don't allow user to connect if he has done too many queries */
@@ -554,9 +562,10 @@ static void reset_mqh(THD *thd, LEX_USER *lu, bool get_them= 0)
     Perform handshake, authorize client and update thd ACL variables.
   SYNOPSIS
     check_connection()
-    thd  INOUT thread handle
+    thd  thread handle
+
   RETURN
-     0  success, OK is sent to user
+     0  success, OK is sent to user, thd is updated.
     -1  error, which is sent to user
    > 0  error code (not sent to user)
 */
@@ -644,14 +653,12 @@ check_connection(THD *thd)
       each handshake.
     */
     create_random_string(thd->scramble, SCRAMBLE_LENGTH, &thd->rand);
-    strmake(thd->scramble_323, thd->scramble, SCRAMBLE_LENGTH_323);
-
     /*
       Old clients does not understand long scrambles, but can ignore packet
       tail: that's why first part of the scramble is placed here, and second
       part at the end of packet.
     */
-    end= strmake(end, thd->scramble_323, SCRAMBLE_LENGTH_323) + 1;
+    end= strmake(end, thd->scramble, SCRAMBLE_LENGTH_323) + 1;
    
     int2store(end, client_flags);
     /* write server characteristics: up to 16 bytes allowed */
@@ -754,8 +761,6 @@ check_connection(THD *thd)
     return(ER_HANDSHAKE_ERROR);
   }
 
-  /* why has it been put here? */
-
   if (thd->client_capabilities & CLIENT_INTERACTIVE)
     thd->variables.net_wait_timeout= thd->variables.net_interactive_timeout;
   if ((thd->client_capabilities & CLIENT_TRANSACTIONS) &&
@@ -778,9 +783,8 @@ check_connection(THD *thd)
 
   if (thd->user)
     x_free(thd->user);
-  thd->user= my_strdup(user, MYF(0));
+  if (!(thd->user= my_strdup(user, MYF(0))))
-  if (!thd->user)
+    return (ER_OUT_OF_RESOURCES);
-    return(ER_OUT_OF_RESOURCES);
   return check_user(thd, COM_CONNECT, passwd, passwd_len, db, true);
 }