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/*
nullidentd.c
Copyright 1999 Brian Young <bayoung@acm.org>
Licensed under the GPL, see the file COPYING included with this distribution.
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <time.h>
#include "version.h"
#define SESSION_TIMEOUT 20
#define MAX_RESPONSE 200
#define MAX_REQUEST 100
#define MAX_USERID 50
#define MAX_RANDOMID 8
void usage()
{
fprintf( stderr, "nullidentd -- version %s\n", VERSION );
fprintf( stderr, "Copyright 1999 Brian Young <bayoung@acm.org>\n" );
fprintf( stderr, "usage: nullidentd [userid]\n" );
}
int write_response( int fd, char *response, int len )
{
int retval;
int byteswritten = 0;
while( byteswritten < len ) {
retval = write( fd, response + byteswritten, len - byteswritten );
if( retval <= 0 ) {
/* error */
return 0;
}
byteswritten += retval;
}
/* success */
return 1;
}
int read_request( int fd, char *request, int maxlen )
{
char c;
int bytesread = 0;
/* read until \n */
while( bytesread < maxlen - 1 ) {
if( read( fd, &c, 1 ) != 1 ) {
/* error */
return 0;
}
if( c == '\n' ) {
/* end of line */
break;
}
request[bytesread] = c;
bytesread += 1;
}
if( bytesread > 0 && request[bytesread-1] == '\r' ) {
/* strip trailing \r */
bytesread -= 1;
}
/* null terminate */
request[bytesread] = '\0';
/* success */
return 1;
}
char *random_userid( void )
{
static char buf[MAX_RANDOMID+1];
size_t i;
static const char valid[] =
"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
for (i = 0 ; i < MAX_RANDOMID ; i++)
buf[i] = valid[rand() % (sizeof(valid) - 1)];
buf[i] = '\0';
return buf;
}
void session_timeout( int foo )
{
exit( 0 );
}
int main( int argc, const char *argv[] )
{
const char * userid = "foobar";
int infd;
int outfd;
int response_len;
char response[MAX_RESPONSE];
char request[MAX_REQUEST];
int gen_random = 0;
if( getgid() == 0 ) {
fprintf( stderr, "Group id is root, exitting.\n" );
return 1;
}
if( getuid() == 0 ) {
fprintf( stderr, "User id is root, exiting.\n" );
return 1;
}
if( argc > 2 ) {
usage();
return 1;
}
if( argc == 2 ) {
/* userid parameter specified */
userid = argv[1];
if( strlen( userid ) > MAX_USERID ) {
fprintf( stderr, "Userid parameter is too long.\n" );
return 1;
}
}
if (strcmp(userid, "RANDOM") == 0) {
gen_random = 1;
}
infd = fileno( stdin );
outfd = fileno( stdout );
// set the session timeout
signal( SIGALRM, session_timeout );
alarm( SESSION_TIMEOUT );
srand(getpid() ^ time(NULL));
for( ;; ) {
/* read the request */
if( !read_request( infd, request, MAX_REQUEST ) ) {
/* error or timed out */
goto done;
}
if (gen_random) {
userid = random_userid();
}
/* format the response */
response_len = snprintf( response, sizeof( response ), "%.20s : USERID : UNIX : %.20s\r\n", request, userid );
/* send the line */
if( !write_response( outfd, response, response_len ) ) {
goto done;
}
}
done:
return 0;
}
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