Re: [GENERAL] Functions in postgres

[Ross J. Reedstrom]

On Wed, Apr 05, 2000 at 12:04:49PM -0500, Victor Manuel Jaquez Leal wrote:
> 
> Hi!

Hi back at ya.

> 
> I know that with \df you can see the functions available in postgres, but
> there must be others not documented just like getpgusername().
> 
> My question is if are there a more complete list of postgres'
> functions.  To be more specific I'm looking for a crypt function.
> 

Then you're in luck. Not as much luck as if there was a built in, but
I've attached my implementation below. I stole a general boiler plate
function from someone else, and modified it to call crypt. The trickiest
part was generating random salt. I use it with these SQL statements:

CREATE FUNCTION "sqlcrypt" (text,text ) RETURNS text AS
'/usr/local/pgsql/data/sqlcrypt.so' LANGUAGE 'C'; 

CREATE FUNCTION "sqlcrypt" (text ) RETURNS text AS 'select
sqlcrypt($1,'''')' LANGUAGE 'SQL';

That way, I can say sqlcrypt('somestring') and it'll return a crypted
version of the string, with a randomly selected salt. I use it for
storing passwords for a web based login: for that, we check logins as 
so:

SELECT * FROM "Personnel" WHERE "PerUsername" = 'RJReedstrom' AND
"PerPassword" = sqlcrypt('password',substr("PerPassword",1,2))

That will only return results if the password hashes match. It does expose
the cleartext of the password between the web server and postgres db:
That's not a problem for us, since they're on the same machine.

Ross
-- 
Ross J. Reedstrom, Ph.D., <[EMAIL PROTECTED]> 
NSBRI Research Scientist/Programmer
Computer and Information Technology Institute
Rice University, 6100 S. Main St.,  Houston, TX 77005

#define _XOPEN_SOURCE
#include <postgres.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <sys/time.h>


text *sqlcrypt(text *key, text *salt);
/*sql create function sqlcrypt(text,text) returns text as 'DESTLIB' language 'c'*/

char *crypt(const char *key, const char *salt);
int rand(void);
void srand(unsigned int seed);


text *sqlcrypt(text *key, text *salt)
{
  text *ret;
  char pass[] = "123456789";
  char s[] = "...";
  char salts[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789./";
  int j,k;
  struct timeval tv;


  s[2]=0;
  bzero(pass,9);
  if ((VARSIZE(salt)-VARHDRSZ) < 2)
    {
    gettimeofday(&tv,0);
    srand((unsigned int)(tv.tv_usec));
    j=(rand() % 64);
    k=(rand() % 64);
    s[0]=salts[j];
    s[1]=salts[k];
	   
    }
  else
    {
    memcpy(s,VARDATA(salt),2);
    }
  ret = palloc(VARHDRSZ + 13);
  bzero(ret,VARHDRSZ + 13);
  VARSIZE(ret) = (VARHDRSZ + 13);
  if ((VARSIZE(key)-VARHDRSZ) < 8)
  {
  	memcpy(pass,VARDATA(key),VARSIZE(key)-VARHDRSZ);
  }
  else
  {
	  memcpy(pass,VARDATA(key),8) ;
  }

  memcpy(VARDATA(ret), crypt(pass,s),13); 

  return ret;
}