static SRP_user_pwd * find_user ( SRP_VBASE * vb , char * username ) {
 int i ;
 SRP_user_pwd * user ;
 if ( vb == NULL ) return NULL ;
 for ( i = 0 ;
 i < sk_SRP_user_pwd_num ( vb -> users_pwd ) ;
 i ++ ) {
 user = sk_SRP_user_pwd_value ( vb -> users_pwd , i ) ;
 if ( strcmp ( user -> id , username ) == 0 ) return user ;
 }
 return NULL ;
 }
static SRP_user_pwd * find_user ( SRP_VBASE * vb , char * username ) {
 int i ;
 SRP_user_pwd * user ;
 if ( vb == NULL ) return NULL ;
 for ( i = 0 ;
 i < sk_SRP_user_pwd_num ( vb -> users_pwd ) ;
 i ++ ) {
 user = sk_SRP_user_pwd_value ( vb -> users_pwd , i ) ;
 if ( strcmp ( user -> id , username ) == 0 ) return user ;
 }
 return NULL ;
 }