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/*
ident.c
This file is part of GNU Anubis.
Copyright (C) 2001, 2002, 2003, 2004, 2005, 2007 The Anubis Team.
GNU Anubis is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version.
GNU Anubis is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with GNU Anubis. If not, see <http://www.gnu.org/licenses/>.
*/
#include "headers.h"
#include "extern.h"
/***********************
IDENT protocol support
************************/
#define USERNAME_C "USERID :"
/* If the reply matches sscanf expression
"%*[^:]: USERID :%*[^:]:%s"
and the length of "%s" part does not exceed size-1 bytes,
copies this part to USERNAME and returns 0. Otherwise,
returns 1 */
static int
ident_extract_username (char *reply, char **pusername)
{
char *p;
p = strchr (reply, ':');
if (!p)
return 1;
if (p[1] != ' ' || strncmp (p + 2, USERNAME_C, sizeof (USERNAME_C) - 1))
return 1;
p += 2 + sizeof (USERNAME_C) - 1;
p = strchr (p, ':');
if (!p)
return 1;
do
p++;
while (*p == ' ');
assign_string (pusername, p);
return 0;
}
/* If the reply matches sscanf expression
"%*[^ ] %*[^ ] %*[^ ] %*[^ ] %*[^ ] %s"
and the length of "%s" part does not exceed size-1 bytes,
copies this part to USERNAME and returns 0. Otherwise,
returns 1 */
static int
crypt_extract_username (char *reply, char **pusername)
{
int i;
char *p = reply;
#define skip_word(c) while (*c && (*c) != ' ') c++
/* Skip five words */
for (i = 0; i < 5; i++)
{
skip_word (p);
if (!*p++)
return 1;
}
assign_string (pusername, p);
return 0;
}
int
auth_ident (struct sockaddr_in *addr, char **user)
{
struct servent *sp;
struct sockaddr_in ident;
char *buf = NULL;
char inetd_buf[LINEBUFFER];
size_t size = 0;
int sd = 0;
int rc;
NET_STREAM str;
size_t nbytes;
if ((sd = socket (AF_INET, SOCK_STREAM, 0)) < 0)
{
anubis_error (0, errno, _("IDENT: socket() failed"));
return 0;
}
memcpy (&ident, addr, sizeof (ident));
sp = getservbyname ("auth", "tcp");
if (sp)
ident.sin_port = sp->s_port;
else
ident.sin_port = htons (113); /* default IDENT port number */
if (connect (sd, (struct sockaddr *) &ident, sizeof (ident)) < 0)
{
anubis_error (0, errno, _("IDENT: connect() failed"));
close_socket (sd);
return 0;
}
net_create_stream (&str, sd);
info (VERBOSE, _("IDENT: connected to %s:%u"),
inet_ntoa (ident.sin_addr), ntohs (ident.sin_port));
snprintf (inetd_buf, sizeof inetd_buf,
"%u , %u" CRLF, ntohs (addr->sin_port), session.anubis_port);
if ((rc = stream_write (str, inetd_buf, strlen (inetd_buf), &nbytes)))
{
anubis_error (0, 0,
_("IDENT: stream_write() failed: %s."),
stream_strerror (str, rc));
net_close_stream (&str);
return 0;
}
if (recvline (CLIENT, str, &buf, &size) == 0)
{
anubis_error (0, 0,
_("IDENT: recvline() failed: %s."),
stream_strerror (str, rc));
net_close_stream (&str);
return 0;
}
net_close_stream (&str);
remcrlf (buf);
if (ident_extract_username (buf, user))
{
info (VERBOSE, _("IDENT: incorrect data."));
free (buf);
return 0;
}
free (buf);
/******************************
IDENTD DES decryption support
*******************************/
if (strstr (*user, "[") && strstr (*user, "]"))
{
int rs = 0;
info (VERBOSE, _("IDENT: data probably encrypted with DES..."));
external_program (&rs, IDECRYPT_PATH, *user, buf, LINEBUFFER);
if (rs == -1)
return 0;
remcrlf (buf);
if (crypt_extract_username (buf, user))
{
info (VERBOSE, _("IDENT: incorrect data (DES deciphered)."));
return 0;
}
else
{ /* UID deciphered */
if (ntohl (ident.sin_addr.s_addr) == INADDR_LOOPBACK)
{
struct passwd *pwd;
int uid = atoi (*user);
pwd = getpwuid (uid);
if (pwd != 0)
assign_string (user, pwd->pw_name);
else
return 0;
}
}
}
info (VERBOSE, _("IDENT: resolved remote user to %s."), *user);
return 1; /* success */
}
/* EOF */
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