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/* PlanC (hubenchang0515@outlook.com) -- an example application
* that implements a custom conversation */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <termios.h>
#include <security/pam_appl.h>
#include <sys/ioctl.h>
/***************************************
* @brief echo off/on
* @param[in] fd file descriptor
* @param[in] off 1 - echo off，0 - echo on
***************************************/
static void echoOff(int fd, int off)
{
struct termios tty;
if (ioctl(fd, TCGETA, &tty) < 0)
{
fprintf(stderr, "TCGETA failed: %s\n", strerror(errno));
return;
}
if (off)
{
tty.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL);
if (ioctl(fd, TCSETAF, &tty) < 0)
{
fprintf(stderr, "TCSETAF failed: %s\n", strerror(errno));
}
}
else
{
tty.c_lflag |= (ECHO | ECHOE | ECHOK | ECHONL);
if (ioctl(fd, TCSETAW, &tty) < 0)
{
fprintf(stderr, "TCSETAW failed: %s\n", strerror(errno));
}
}
}
/***************************************
* @brief echo off stdin
***************************************/
static void echoOffStdin(void)
{
echoOff(fileno(stdin), 1);
}
/***************************************
* @brief echo on stdin
***************************************/
static void echoOnStdin(void)
{
echoOff(fileno(stdin), 0);
}
/***************************************
* @brief read a line input
* @return the input string
***************************************/
static char *readline(void)
{
char input[PAM_MAX_RESP_SIZE];
int i;
flockfile(stdin);
for (i = 0; i < PAM_MAX_RESP_SIZE; i++)
{
int ch = getchar_unlocked();
if (ch == '\n' || ch == '\r' ||ch == EOF)
break;
input[i] = ch;
}
funlockfile(stdin);
input[i] = '\0';
return (strdup(input));
}
/**************************************************
* @brief callback of PAM conversation
* @param[in] num_msg the count of message
* @param[in] msg PAM message
* @param[out] resp our response
* @param[in] appdata_ptr custom data passed by struct pam_conv.appdata_ptr
* @return state
**************************************************/
static int conversation(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr)
{
(void)(appdata_ptr);
int i;
/* check the count of message */
if (num_msg <= 0 || num_msg >= PAM_MAX_MSG_SIZE)
{
fprintf(stderr, "invalid num_msg(%d)\n", num_msg);
return PAM_CONV_ERR;
}
/* alloc memory for response */
if ((resp[0] = malloc(num_msg * sizeof(struct pam_response))) == NULL)
{
fprintf(stderr, "bad alloc\n");
return PAM_BUF_ERR;
}
/* response for message */
for (i = 0; i < num_msg; i++)
{
const struct pam_message *m = *msg + i;
struct pam_response *r = *resp + i;
r->resp_retcode = 0; /* currently un-used, zero expected */
switch (m->msg_style)
{
case PAM_PROMPT_ECHO_OFF: /* get the input with echo off, like the password */
printf("%s", m->msg);
echoOffStdin();
r->resp = readline();
echoOnStdin();
printf("\n");
break;
case PAM_PROMPT_ECHO_ON: /* get the input with echo on, like the username */
printf("%s", m->msg);
r->resp = readline();
break;
case PAM_TEXT_INFO: /* normal info */
printf("%s\n", m->msg);
break;
case PAM_ERROR_MSG: /* error info */
fprintf(stderr, "%s\n", m->msg);
break;
default:
fprintf(stderr, "unexpected msg_style: %d\n", m->msg_style);
break;
}
}
return PAM_SUCCESS;
}
int main(void)
{
struct pam_conv pam_conv = {conversation, NULL};
pam_handle_t *pamh;
/* echo on while exist, like Ctrl+C on input password */
atexit(echoOnStdin);
if (PAM_SUCCESS != pam_start("login", NULL, &pam_conv, &pamh))
{
fprintf(stderr, "pam_start failed\n");
return EXIT_FAILURE;
}
if (PAM_SUCCESS != pam_authenticate(pamh, 0))
{
fprintf(stderr, "pam_authenticate failed\n");
pam_end(pamh, 0);
return EXIT_FAILURE;
}
if (PAM_SUCCESS != pam_acct_mgmt(pamh, 0))
{
fprintf(stderr, "pam_acct_mgmt failed\n");
pam_end(pamh, 0);
return EXIT_FAILURE;
}
pam_end(pamh, 0);
return EXIT_SUCCESS;
}
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