C言語でPAMを使ってログイン認証

pam_login.c

#include <security/pam_appl.h>
#include <security/pam_misc.h>
#include <stdio.h>
#include <string.h>

#define USERNAME "this is username"
#define PASSWORD "this is password"


static int conv_func(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr) {
	int retval = PAM_CONV_ERR;

	for (int i=0; i<num_msg; i++) {
		if (msg[i]->msg_style == PAM_PROMPT_ECHO_OFF && strncmp(msg[i]->msg, "Password: ", 10) == 0) {
			struct pam_response *resp_msg = malloc(sizeof(struct pam_response));

			char *password = malloc(strlen(PASSWORD));
			strcpy(password, PASSWORD);

			resp_msg->resp_retcode = 0;
			resp_msg->resp = password;
			resp[i] = resp_msg;
			retval = PAM_SUCCESS;
		}
	}

	return retval;
}

const struct pam_conv conv = {
	conv_func,
	NULL
};

int main(int argc, char **argv) {
	pam_handle_t* pamh = NULL;
	int retval;

	retval = pam_start("login", USERNAME, &conv, &pamh);

	if (retval == PAM_SUCCESS) {
		printf("credentials accepted.\n");
		retval = pam_authenticate(pamh, 0);
	}

	if (retval == PAM_SUCCESS) {
		printf("valid.\n");
		retval = pam_acct_mgmt(pamh, 0);
	}

	if (retval == PAM_SUCCESS) {
		printf("authenticated\n");
	} else {
		printf("not authenticated\n");
	}

	if (pam_end(pamh, retval) != PAM_SUCCESS) {
		pamh = NULL;
		printf("failed to release\n");
		exit(1);
	}

	return retval == PAM_SUCCESS ? 0 : 1;
}