ssl_passphrase_func.c

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/*-------------------------------------------------------------------------
 *
 * ssl_passphrase_func.c
 *
 * Loadable PostgreSQL module fetch an ssl passphrase for the server cert.
 * instead of calling an external program. This implementation just hands
 * back the configured password rot13'd.
 *
 *-------------------------------------------------------------------------
 */
 
#include "postgres.h"
 
#include <float.h>
#include <stdio.h>
 
#include "libpq/libpq.h"
#include "libpq/libpq-be.h"
#include "utils/guc.h"
 
PG_MODULE_MAGIC;
 
static char *ssl_passphrase = NULL;
 
/* callback function */
static int  rot13_passphrase(char *buf, int size, int rwflag, void *userdata);
 
/* hook function to set the callback */
static void set_rot13(SSL_CTX *context, bool isServerStart);
 
/*
 * Module load callback
 */
void
_PG_init(void)
{
    /* Define custom GUC variable. */
    DefineCustomStringVariable("ssl_passphrase.passphrase",
                               "passphrase before transformation",
                               NULL,
                               &ssl_passphrase,
                               NULL,
                               PGC_SIGHUP,
                               0,   /* no flags required */
                               NULL,
                               NULL,
                               NULL);
 
    MarkGUCPrefixReserved("ssl_passphrase");
 
    if (ssl_passphrase)
        openssl_tls_init_hook = set_rot13;
}
 
static void
set_rot13(SSL_CTX *context, bool isServerStart)
{
    /* warn if the user has set ssl_passphrase_command */
    if (ssl_passphrase_command[0])
        ereport(WARNING,
                (errmsg("\"ssl_passphrase_command\" setting ignored by ssl_passphrase_func module")));
 
    SSL_CTX_set_default_passwd_cb(context, rot13_passphrase);
}
 
static int
rot13_passphrase(char *buf, int size, int rwflag, void *userdata)
{
 
    Assert(ssl_passphrase != NULL);
    strlcpy(buf, ssl_passphrase, size);
    for (char *p = buf; *p; p++)
    {
        char        c = *p;
 
        if ((c >= 'a' && c <= 'm') || (c >= 'A' && c <= 'M'))
            *p = c + 13;
        else if ((c >= 'n' && c <= 'z') || (c >= 'N' && c <= 'Z'))
            *p = c - 13;
    }
 
    return strlen(buf);
}