/*
 * Alternative checkpassword for QPopup by Jedi/Sector One <j@4u.net>
 *
 * Format of the configuration file is :
 * pop_login:crypted_password:real_login:path
 *
 * Syslog logging added by Paul Gregg <pgregg@tibus.net> Dec 1997
 * compile by: gcc -o checkpoppasswd checkpoppasswd.c -lcrypt
 * Original URL of this file: http://www.pgregg.com/projects/
 */

#include "../main.h"

#ifndef CONFIG_FILE
#  error Constant CONFIG_FILE not defined. Define in ../main.h.
#endif

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <limits.h>
#include <sys/types.h>
#include <pwd.h>
#include <errno.h>

#ifndef SYSLOG_LEVEL
#  error SYSLOG_LEVEL not defined
#else
#  if SYSLOG_LEVEL >= 1
#    include <syslog.h>
#  endif
#endif

#ifndef LINE_MAX
#  define LINE_MAX 2048
#endif

#ifndef LOGIN_MAX
#  define LOGIN_MAX 16
#endif

extern int errno;

extern char *crypt();
/* extern char *malloc(); */
extern char **environ;

extern char *login;
extern char *password;

extern char remotehost[BUFLEN];
extern char remoteip[BUFLEN];
extern char remoteinfo[BUFLEN];

static char *str1e2(char *name, char *value)
{
	char *nv;
	nv = malloc(strlen(name) + strlen(value) + 2);
	if (!nv) {
#if SYSLOG_LEVEL >= 1
		syslog(SYSLOG_ERROR, "user: exit 111 at point 1");
#endif
		exit(111);
	}
	strcpy(nv,name);
	strcat(nv,"=");
	strcat(nv,value);
	return nv;
}

static struct newpw {
	char *pw_passwd;
	char *pw_dir;
	char *pw_name;
	char *pw_shell;
	uid_t pw_uid;
	gid_t pw_gid;
	char *pw_real;
} *newgetpwnam(char *newlogin)
{
	static char line[LINE_MAX + 1];
	static struct newpw npw;
	struct passwd *pw;
	char *tlogin = NULL;
	FILE *fp;

	if ((fp = fopen(CONFIG_FILE, "rt")) == NULL) {
#if SYSLOG_LEVEL >= 1
		syslog(SYSLOG_ERROR, "user: exit 2 at point 2");
#endif
		exit(2);
	}

	/* TODO:
	 *
	 * Fix problem, when line is longer than LINE_MAX.
	 * Allow to use empty (but only empty) lines in config file.
	 *
	 * Nepto [17/4/2002]
	 */

	while (fgets(line, LINE_MAX, fp) != NULL) {
		char *linepnt;

		if ((linepnt = strchr(line, '\n')) != NULL)
			*linepnt = 0;

		if ((linepnt = strtok(line, ":")) == NULL) {
#if SYSLOG_LEVEL >= 1
			syslog(SYSLOG_ERROR, "user: invalid line, aborting");
#endif
			exit(2);
		}

		if (strcmp(linepnt, newlogin) == 0) {
			npw.pw_real = linepnt;
			if ((linepnt = strtok(NULL, ":")) == NULL) {
#if SYSLOG_LEVEL >= 1
				syslog(SYSLOG_ERROR, "user: exit 2 at point 4");
#endif
				exit(2);
			}
			npw.pw_passwd = linepnt;
			if ((linepnt = strtok(NULL, ":")) == NULL) {
#if SYSLOG_LEVEL >= 1
				syslog(SYSLOG_ERROR, "user: exit 2 at point 5");
#endif
				exit(2);
			}
			*(linepnt - 1) = 0;
			tlogin = linepnt;
			if ((linepnt = strtok(NULL, ":")) == NULL) {
#if SYSLOG_LEVEL >= 1
				syslog(SYSLOG_ERROR, "user: exit 2 at point 6");
#endif
				exit(2);
			}
			npw.pw_dir = linepnt;
			break;
		}
	}

	fclose(fp);

	if (tlogin == NULL) {
		return NULL;
	}

	pw = getpwnam(tlogin);
	if (!pw) {
#if SYSLOG_LEVEL >= 1
		syslog(SYSLOG_ERROR, "user: exit 1 at point 8");
#endif
		exit(1); /* XXX: unfortunately getpwnam() hides temporary errors */
	}

	npw.pw_name = tlogin;
	npw.pw_shell = pw->pw_shell;
	npw.pw_uid = pw->pw_uid;
	npw.pw_gid = pw->pw_gid;

	return &npw;
}

int main_user(int argc, char **argv, char *envp[])
{
	struct newpw *pw;
	char *stored;
	char *encrypted;
	char **newenv;
	int numenv;

	/* Here we have global variables:
	   1. login
	   2. password
	   */

	pw = newgetpwnam(login);
	if (! pw) {
#if SYSLOG_LEVEL >= 3
		syslog(SYSLOG_INFO, "user: FAILED: unknown username: %s", login);
#endif
		return -1;
	}
	stored = pw->pw_passwd;

	encrypted = crypt(password, stored);

	if (!*stored || strcmp(encrypted,stored)) {
#if SYSLOG_LEVEL >= 3
		syslog(SYSLOG_INFO, "user: FAILED: %s [%s]"
				" - password incorrect (%s) from %s@%s [%s]",
				login, pw->pw_real, password, remoteinfo, remotehost, remoteip);
#endif
		return -1;
	}

	nuke_dynamic_string(&login);
	nuke_dynamic_string(&password);

	if (!pw->pw_uid) {
#if SYSLOG_LEVEL >= 1
		syslog(SYSLOG_ERROR, "user: exit 1 at point 15");
#endif
		exit(1);
	}

	/* pgregg - always use 888
	   if (setgid(888) == -1) { */
	if (setgid(pw->pw_gid) == -1) {
#if SYSLOG_LEVEL >= 1
		syslog(SYSLOG_ERROR, "user: exit 1 at point 16");
#endif
		exit(1);
	}

	if (setuid(pw->pw_uid) == -1) {
#if SYSLOG_LEVEL >= 1
		syslog(SYSLOG_ERROR, "user: exit 1 at point 17");
#endif
		exit(1);
	}

	if (chdir(pw->pw_dir) == -1) {
#if SYSLOG_LEVEL >= 3
		syslog(SYSLOG_INFO, "user: FAILED: %s"
				" - unable to change to Mail directory: %s",
				pw->pw_real, pw->pw_dir);
#endif
		exit(111);
	}

	if (getuid() < 500) {
#if SYSLOG_LEVEL >= 3
		syslog(SYSLOG_INFO, "user: DENIED: POP3 user's UID < 500");
#endif
		exit(1);
	}


	numenv = 0;
	while (environ[numenv])
		++numenv;
	newenv = (char **) malloc((numenv + 4) * sizeof(char *));
	if (!newenv) {
#if SYSLOG_LEVEL >= 1
		syslog(SYSLOG_ERROR, "user: exit 111 at point 20 (%s)", argv[1]);
#endif
		exit(111);
	}

	{
		register int i;

		for (i = 0;i < numenv;++i)
			newenv[i] = environ[i];
	}

	newenv[numenv++] = str1e2("USER",pw->pw_name);
	newenv[numenv++] = str1e2("HOME",pw->pw_dir);
	newenv[numenv++] = str1e2("SHELL",pw->pw_shell);
	newenv[numenv] = 0;
	environ = newenv;

#if SYSLOG_LEVEL >= 3
	syslog(SYSLOG_INFO, "user:"
			" POP3 user %s : %s logged in from %s@%s [%s]",
			pw->pw_real, pw->pw_dir, remoteinfo, remotehost, remoteip);
#endif

	execvp(argv[1],argv + 1);
	exit(111);

	return 0;
}