RE: SASL authentication

> -----Original Message-----
> From: Rich Megginson [mailto:[email protected]] 
> Sent: Friday, June 12, 2009 11:13 PM
> To: Xu, Qiang (FXSGSC)
> Cc: [email protected]; Howard Chu
> Subject: Re: SASL authentication
> 
> This is a very dangerous use of strncpy - strncpy does not null 
> terminate the buffer- if you want to use strncpy, you must 
> ensure that the string is properly null terminated.

Actually, the code snippet is part of a function:
=======================================================
static AbaInitStatus
aba_ldap_init_sasl_p(LDAP **ldapSearchHandle, bool_t testFlag,
                     char* username, char* password, 
                     SM_Session_Information_Type *sessionInformation)
{
  int ldapStatus = LDAP_SUCCESS;
  AbaInitStatus status = ABA_OK;
  LDAP   *ldapHandle = (LDAP *)NULL;
  ...
  LDAPControl **responseControls = NULL;
  char primaryIP[PRIMARY_HOSTNAME+1] = {0};
  ...
  /* convert primary server hostname to IP address */
  if (is_it_an_IP_address(primaryServerHost) == FALSE)
  {
  	strncpy(primaryIP, primaryServerHost, PRIMARY_HOSTNAME);
  	if (get_ip_from_hostname(primaryServerHost, primaryIP))
            {
        	    LOGINFO("primary server IP address is %s", primaryIP);
            }
            else
            {
        	   LOGERROR("get_ip_from_hostname() failed for primary server, still using hostname!");
        	   strncpy(primaryIP, primaryServerHost, PRIMARY_HOSTNAME);
            }
  }
  else
  {
            LOGINFO("primary server is already in IP address form");
            strncpy(primaryIP, primaryServerHost, PRIMARY_HOSTNAME);
  }

...

  if ((ldapHandle = prldap_init(primaryIP,
                                          primaryServerPort, 1 )) == NULL)
  {
      LOGERROR("Failed to do prldap_init for Primary Server...");
      return(ABA_LDAP_INIT_CALL_FAILED);
  }
  else
  {
      LOGINFO("prldap_init SUCCESSFUL to [%s:%d]", 
                      primaryIP, primaryServerPort);
  }

...

  ldapStatus = ldap_sasl_interactive_bind_ext_s(ldapHandle, "", sasl_mech,
                                                                      NULL, NULL, sasl_flags,
                                                                      example_sasl_interact, NULL, &responseControls);

  if (responseControls != NULL)
  {
  	LOGINFO("SASL binding finished, will destroy responseControls");
  	ldap_controls_free(responseControls);
  	responseControls = NULL;
  }

  LOGINFO("SASL LDAP BIND with GSSAPI: Value of ldapStatus %d", ldapStatus); 
  ...
}
=======================================================
As you can see, the char array primaryIP[] is a local variable, and it would be initialized to 0 blocks every time the function is called. Therefore, strncpy() here is safe.  :-)

Thanks for reminding, Rich!
Xu Qiang