Viewing file:  upperLOWER.c (3.69 KB) -rw-r--r--
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/*
* This is a sample filter program, for use with pam_filter (a module
* provided with Linux-PAM). This filter simply transposes upper and
* lower case letters, it is intended for demonstration purposes and
* it serves no purpose other than to annoy the user...
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include "pam_filter.h"
#include <security/pam_modules.h>
#include <security/_pam_macros.h>
#include <security/pam_modutil.h>
/* ---------------------------------------------------------------- */
#include <ctype.h>
static void do_transpose(char *buffer,int len)
{
int i;
for (i=0; i<len; ++i) {
if (islower(buffer[i])) {
buffer[i] = toupper(buffer[i]);
} else {
buffer[i] = tolower(buffer[i]);
}
}
}
extern char **environ;
int main(int argc, char **argv UNUSED)
{
char buffer[BUFSIZ];
fd_set readers;
void (*before_user)(char *,int);
void (*before_app)(char *,int);
openlog("upperLOWER", LOG_CONS|LOG_PID, LOG_AUTHPRIV);
#ifdef DEBUG
{
int i;
fprintf(stderr,"environment :[\r\n");
for (i=0; environ[i]; ++i) {
fprintf(stderr,"-> %s\r\n",environ[i]);
}
fprintf(stderr,"]: end\r\n");
}
#endif
if (argc != 1) {
#ifdef DEBUG
fprintf(stderr,"filter invoked as conventional executable\n");
#else
syslog(LOG_ERR, "filter invoked as conventional executable");
#endif
exit(1);
}
before_user = before_app = do_transpose; /* assign filter functions */
/* enter a loop that deals with the input and output of the
user.. passing it to and from the application */
FD_ZERO(&readers); /* initialize reading mask */
for (;;) {
FD_SET(APPOUT_FILENO, &readers); /* wake for output */
FD_SET(APPERR_FILENO, &readers); /* wake for error */
FD_SET(STDIN_FILENO, &readers); /* wake for input */
if ( select(APPTOP_FILE,&readers,NULL,NULL,NULL) < 0 ) {
#ifdef DEBUG
fprintf(stderr,"select failed\n");
#else
syslog(LOG_WARNING,"select failed");
#endif
break;
}
/* application errors */
if ( FD_ISSET(APPERR_FILENO,&readers) ) {
int got = pam_modutil_read(APPERR_FILENO, buffer, BUFSIZ);
if (got <= 0) {
break;
} else {
/* translate to give to real terminal */
if (before_user != NULL)
before_user(buffer, got);
if (pam_modutil_write(STDERR_FILENO, buffer, got) != got ) {
syslog(LOG_WARNING,"couldn't write %d bytes?!",got);
break;
}
}
} else if ( FD_ISSET(APPOUT_FILENO,&readers) ) { /* app output */
int got = pam_modutil_read(APPOUT_FILENO, buffer, BUFSIZ);
if (got <= 0) {
break;
} else {
/* translate to give to real terminal */
if (before_user != NULL)
before_user(buffer, got);
if (pam_modutil_write(STDOUT_FILENO, buffer, got) != got ) {
syslog(LOG_WARNING,"couldn't write %d bytes!?",got);
break;
}
}
}
if ( FD_ISSET(STDIN_FILENO, &readers) ) { /* user input */
int got = pam_modutil_read(STDIN_FILENO, buffer, BUFSIZ);
if (got < 0) {
syslog(LOG_WARNING,"user input junked");
break;
} else if (got) {
/* translate to give to application */
if (before_app != NULL)
before_app(buffer, got);
if (pam_modutil_write(APPIN_FILENO, buffer, got) != got ) {
syslog(LOG_WARNING,"couldn't pass %d bytes!?",got);
break;
}
} else {
/* nothing received -- an error? */
syslog(LOG_WARNING,"user input null?");
break;
}
}
}
exit(0);
}
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