/*
 *  gensiotools - General tools using gensio
 *  Copyright (C) 2019  Corey Minyard <minyard@acm.org>
 *
 *  SPDX-License-Identifier: GPL-2.0-only
 *
 *  In addition, as a special exception, the copyright holders of
 *  gensio give you permission to combine gensio with free software
 *  programs or libraries that are released under the GNU LGPL and
 *  with code included in the standard release of OpenSSL under the
 *  OpenSSL license (or modified versions of such code, with unchanged
 *  license). You may copy and distribute such a system following the
 *  terms of the GNU GPL for gensio and the licenses of the other code
 *  concerned, provided that you include the source code of that
 *  other code when and as the GNU GPL requires distribution of source
 *  code.
 *
 *  Note that people who make modified versions of gensio are not
 *  obligated to grant this special exception for their modified
 *  versions; it is their choice whether to do so. The GNU General
 *  Public License gives permission to release a modified version
 *  without this exception; this exception also makes it possible to
 *  release a modified version which carries forward this exception.
 */

#include "config.h"
#ifdef _WIN32
#include <winsock2.h>
#include <Windows.h>
#include <Lmcons.h>
#include <ntsecapi.h>
#include <userenv.h>
#include <wtsapi32.h>
#include <sddl.h>
#endif

#include "gtlssh.h"
#include "utils.h"
#include <stdio.h>

/* Should use sysconf to get this eventually. */
#ifndef HOST_NAME_MAX
#define HOST_NAME_MAX 255
#endif

#define GTLSSHDIR DIRSEPS ".gtlssh"

#ifdef _WIN32
#include <gensio/gensio_osops.h>

static char *gtlssh_confdir;

static int
drop_last_diritem(char *dir)
{
    char *s, *s2;

    s = strrchr(dir, '/');
    s2 = strrchr(dir, '\\');
    if (!s && !s2)
	return 0;
    if (s && s2) {
	if (s < s2)
	    s = s2;
	} else if (s2) {
	s = s2;
    }
    *s = '\0';
    return 1;
}

const char *
get_confdir(void)
{
    char dir[256];
    DWORD rv;

    if (!gtlssh_confdir) {
	rv = GetModuleFileNameA(NULL, dir, sizeof(dir));
	if (rv == 0)
	    return NULL;
	if (!drop_last_diritem(dir))
	    return NULL;
	if (!drop_last_diritem(dir))
	    return NULL;
	gtlssh_confdir = alloc_sprintf("%s\\etc\\gtlssh", dir);
    }
    return gtlssh_confdir;
}

char *
get_homedir(gtlssh_logger logger, void *cbdata,
	    const char *username, const char *extra)
{
    DWORD extra_len = 0;
    char *dir;

    if (!extra)
	extra = "";
    extra_len = strlen(extra);

    if (!username) {
	DWORD drive_len = 0, path_len, rv;
	bool have_userprofile = false;

	path_len = GetEnvironmentVariable("USERPROFILE", NULL, 0);
	if (path_len != 0) {
	    path_len--;
	    have_userprofile = true;
	} else {
	    drive_len = GetEnvironmentVariable("HOMEDRIVE", NULL, 0);
	    if (drive_len == 0) {
		logger(cbdata, "No HOMEDRIVE or USERPROFILE set\n");
		return NULL;
	    }
	    /* Docs say return value includes the nil terminator. */
	    drive_len--;
	    path_len = GetEnvironmentVariable("HOMEPATH", NULL, 0);
	    if (path_len == 0) {
		logger(cbdata, "No HOMEPATH or USERPROFILE set\n");
		return NULL;
	    }
	    path_len--;
	}

	dir = malloc(drive_len + path_len + extra_len + 1);
	if (!dir) {
	    logger(cbdata, "Out of memory allocating home dir\n");
	    return NULL;
	}

	if (have_userprofile) {
	    rv = GetEnvironmentVariable("USERPROFILE", dir, path_len + 1);
	    if (rv != path_len) {
		free(dir);
		logger(cbdata, "No USERPROFILE set\n");
		return NULL;
	    }
	} else {
	    rv = GetEnvironmentVariable("HOMEDRIVE", dir, drive_len + 1);
	    if (rv != drive_len) {
		free(dir);
		logger(cbdata, "No HOMEDRIVE set\n");
		return NULL;
	    }
	    rv = GetEnvironmentVariable("HOMEPATH", dir + drive_len,
					path_len + 1);
	    if (rv != path_len) {
		free(dir);
		logger(cbdata, "No HOMEPATH set\n");
		return NULL;
	    }
	}
	strncpy(dir + drive_len + path_len, extra, extra_len + 1);
    } else {
	HANDLE userh = NULL;
	DWORD err, len;
	char dummy[1];

	err = gensio_win_get_user_token(username, NULL, "gtlssh", NULL, false,
					&userh);
	if (err) {
	    char errbuf[128];

	    FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL,
			  err, 0, errbuf, sizeof(errbuf), NULL);
	    logger(cbdata, "Could not get user: %s\n", errbuf);
	    return NULL;
	}

	len = 0;
	if (!GetUserProfileDirectoryA(userh, dummy, &len) &&
		(GetLastError() != ERROR_INSUFFICIENT_BUFFER)) {
	    char errbuf[128];

	    FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL,
			  GetLastError(), 0, errbuf, sizeof(errbuf), NULL);
	    logger(cbdata, "GetUserProfileDirectory: %s\n", errbuf);
	    CloseHandle(userh);
	    return NULL;
	}
	dir = malloc(len + extra_len);
	if (!dir) {
	    logger(cbdata, "Out of memory allocating home dir\n");
	    CloseHandle(userh);
	    return NULL;
	}
	GetUserProfileDirectoryA(userh, dir, &len);
	CloseHandle(userh);
	strncpy(dir + len - 1, extra, extra_len + 1);
    }

    return dir;
}

char *
get_my_username(gtlssh_logger logger, void *cbdata)
{
    char *username = malloc(UNLEN + 1);
    DWORD len = UNLEN + 1;

    if (!username) {
	logger(cbdata, "out of memory allocating username\n");
	return NULL;
    }

    if (!GetUserNameA(username, &len)) {
	DWORD err = GetLastError();
	char errbuf[128];

	free(username);
	FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL,
		      err, 0, errbuf, sizeof(errbuf), NULL);
	logger(cbdata, "Could not get username: %s\n", errbuf);
	return NULL;
    }

    return username;
}

#else

#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <pwd.h>
#include <limits.h>
#include <errno.h>

const char *
get_confdir(void)
{
    return SYSCONFDIR "/gtlssh";
}

char *
get_homedir(gtlssh_logger logger, void *cbdata,
	    const char *username, const char *extra)
{
    char *dir;

    if (!extra)
	extra = "";

    if (!username) {
	const char *home = getenv("HOME");

	if (!home) {
	    logger(cbdata, "No home directory set\n");
	    return NULL;
	}

	dir = alloc_sprintf("%s%s", home, extra);
    } else {
	struct passwd *pw = getpwnam(username);
	
	dir = alloc_sprintf("%s%s", pw->pw_dir, extra);
    }

    if (!dir) {
	logger(cbdata, "Out of memory allocating gtlssh dir\n");
	return NULL;
    }

    return dir;
}

char *
get_my_username(gtlssh_logger logger, void *cbdata)
{
    struct passwd *pw = getpwuid(getuid());
    char *username;

    if (!pw) {
	logger(cbdata, "no username given, and can't look up UID\n");
	return NULL;
    }
    username = strdup(pw->pw_name);
    if (!username) {
	logger(cbdata, "out of memory allocating username\n");
	return NULL;
    }

    return username;
}

#endif /* _WIN32 */

char *
get_tlsshdir(gtlssh_logger logger, void *cbdata,
	     const char *username, const char *extra)
{
    char *hextra = GTLSSHDIR;
    bool hextra_alloced = false;
    char *dir;

    if (extra) {
	hextra = alloc_sprintf("%s%s", GTLSSHDIR, extra);
	if (!hextra) {
	    logger(cbdata, "Could not allocate tlsshdir\n");
	    return NULL;
	}
	hextra_alloced = true;
    }
    dir = get_homedir(logger, cbdata, username, hextra);
    if (hextra_alloced)
	free(hextra);
    return dir;
}

char *
get_my_hostname(gtlssh_logger logger, void *cbdata)
{
    char hostname[HOST_NAME_MAX + 1];

    if (gethostname(hostname, sizeof(hostname)) != 0) {
#ifdef _WIN32
	int err = WSAGetLastError();
	char errbuf[128];

	FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL,
		      err, 0, errbuf, sizeof(errbuf), NULL);
	logger(cbdata, "Could not get hostname: %s\n", errbuf);
#else
	logger(cbdata, "Could not get hostname: %s\n", strerror(errno));
#endif
	return NULL;
    }
    return strdup(hostname);
}