/**
 * FreeRDP: A Remote Desktop Protocol Implementation
 * Certificate Handling
 *
 * Copyright 2011 Jiten Pathy
 * Copyright 2011-2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#include <winpr/crypto.h>
#include <winpr/crt.h>
#include <winpr/file.h>
#include <winpr/path.h>

#include <openssl/pem.h>
#include <openssl/rsa.h>

static const char certificate_store_dir[] = "certs";
static const char certificate_server_dir[] = "server";
static const char certificate_known_hosts_file[] = "known_hosts2";
static const char certificate_legacy_hosts_file[] = "known_hosts";

#include <freerdp/log.h>
#include <freerdp/crypto/certificate.h>

#define TAG FREERDP_TAG("crypto")

static BOOL certificate_split_line(char* line, char** host, UINT16* port,
                                   char** subject, char** issuer,
                                   char** fingerprint);
static BOOL certificate_line_is_comment(const char* line, size_t length)
{
	while (length > 0)
	{
		switch (*line)
		{
			case ' ':
			case '\t':
				line++;
				length--;
				break;

			case '#':
				return TRUE;

			default:
				return FALSE;
		}
	}

	if (length < 1)
		return TRUE;

	return FALSE;
}

BOOL certificate_store_init(rdpCertificateStore* certificate_store)
{
	char* server_path = NULL;
	rdpSettings* settings;
	settings = certificate_store->settings;

	if (!PathFileExistsA(settings->ConfigPath))
	{
		if (!PathMakePathA(settings->ConfigPath, 0))
		{
			WLog_ERR(TAG, "error creating directory '%s'", settings->ConfigPath);
			goto fail;
		}

		WLog_INFO(TAG, "creating directory %s", settings->ConfigPath);
	}

	if (!(certificate_store->path = GetCombinedPath(settings->ConfigPath,
	                                (char*) certificate_store_dir)))
		goto fail;

	if (!PathFileExistsA(certificate_store->path))
	{
		if (!PathMakePathA(certificate_store->path, 0))
		{
			WLog_ERR(TAG, "error creating directory [%s]", certificate_store->path);
			goto fail;
		}

		WLog_INFO(TAG, "creating directory [%s]", certificate_store->path);
	}

	if (!(server_path = GetCombinedPath(settings->ConfigPath, (char*) certificate_server_dir)))
		goto fail;

	if (!PathFileExistsA(server_path))
	{
		if (!PathMakePathA(server_path, 0))
		{
			WLog_ERR(TAG, "error creating directory [%s]", server_path);
			goto fail;
		}

		WLog_INFO(TAG, "created directory [%s]", server_path);
	}

	if (!(certificate_store->file = GetCombinedPath(settings->ConfigPath,
	                                (char*) certificate_known_hosts_file)))
		goto fail;

	if (!(certificate_store->legacy_file = GetCombinedPath(settings->ConfigPath,
	                                       (char*) certificate_legacy_hosts_file)))
		goto fail;

	free(server_path);
	return TRUE;
fail:
	WLog_ERR(TAG, "certificate store initialization failed");
	free(server_path);
	free(certificate_store->path);
	free(certificate_store->file);
	certificate_store->path = NULL;
	certificate_store->file = NULL;
	return FALSE;
}

static int certificate_data_match_legacy(rdpCertificateStore* certificate_store,
        rdpCertificateData* certificate_data)
{
	HANDLE fp;
	int match = 1;
	char* data;
	char* mdata;
	char* pline;
	char* hostname = NULL;
	DWORD lowSize, highSize;
	UINT64 size;
	size_t length;
	DWORD read;
	/* Assure POSIX style paths, CreateFile expects either '/' or '\\' */
	PathCchConvertStyleA(certificate_store->legacy_file, strlen(certificate_store->legacy_file),
	                     PATH_STYLE_UNIX);
	fp = CreateFileA(certificate_store->legacy_file, GENERIC_READ, FILE_SHARE_READ,
	                 NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

	if (fp == INVALID_HANDLE_VALUE)
		return match;

	if ((lowSize = GetFileSize(fp, &highSize)) == INVALID_FILE_SIZE)
	{
		WLog_ERR(TAG, "GetFileSize(%s) returned %s [0x%08"PRIX32"]",
		         certificate_store->legacy_file, strerror(errno), GetLastError());
		CloseHandle(fp);
		return match;
	}

	size = (UINT64)lowSize | ((UINT64)highSize << 32);

	if (size < 1)
	{
		CloseHandle(fp);
		return match;
	}

	mdata = (char*) malloc(size + 2);

	if (!mdata)
	{
		CloseHandle(fp);
		return match;
	}

	data = mdata;

	if (!ReadFile(fp, data, size, &read, NULL) || (read != size))
	{
		free(data);
		CloseHandle(fp);
		return match;
	}

	CloseHandle(fp);
	data[size] = '\n';
	data[size + 1] = '\0';
	pline = StrSep(&data, "\r\n");

	while (pline != NULL)
	{
		length = strlen(pline);

		if (length > 0)
		{
			hostname = StrSep(&pline, " \t");

			if (!hostname || !pline)
				WLog_WARN(TAG, "Invalid %s entry %s %s!", certificate_legacy_hosts_file,
				          hostname, pline);
			else if (strcmp(hostname, certificate_data->hostname) == 0)
			{
				const int diff = strcmp(pline, certificate_data->fingerprint);
				match = (diff == 0) ? 0 : -1;
				break;
			}
		}

		pline = StrSep(&data, "\r\n");
	}

	/* Found a valid fingerprint in legacy file,
	 * copy to new file in new format. */
	if (0 == match)
	{
		rdpCertificateData* data = certificate_data_new(
		                               hostname,
		                               certificate_data->port,
		                               NULL, NULL,
		                               certificate_data->fingerprint);

		if (data)
		{
			free(data->subject);
			free(data->issuer);
			data->subject = NULL;
			data->issuer = NULL;

			if (certificate_data->subject)
			{
				data->subject = _strdup(certificate_data->subject);

				if (!data->subject)
					goto out;
			}

			if (certificate_data->issuer)
			{
				data->issuer = _strdup(certificate_data->issuer);

				if (!data->issuer)
					goto out;
			}

			match = certificate_data_print(certificate_store, data) ? 0 : 1;
		}

	out:
		certificate_data_free(data);
	}

	free(mdata);
	return match;
}

static int certificate_data_match_raw(rdpCertificateStore* certificate_store,
                                      rdpCertificateData* certificate_data,
                                      char** psubject, char** pissuer,
                                      char** fprint)
{
	BOOL found = FALSE;
	HANDLE fp;
	size_t length;
	char* data;
	char* mdata;
	char* pline;
	int match = 1;
	DWORD lowSize, highSize;
	UINT64 size;
	char* hostname = NULL;
	char* subject = NULL;
	char* issuer = NULL;
	char* fingerprint = NULL;
	unsigned short port = 0;
	DWORD read;
	/* Assure POSIX style paths, CreateFile expects either '/' or '\\' */
	PathCchConvertStyleA(certificate_store->file, strlen(certificate_store->file), PATH_STYLE_UNIX);
	fp = CreateFileA(certificate_store->file, GENERIC_READ, FILE_SHARE_READ,
	                 NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_HIDDEN | FILE_ATTRIBUTE_NORMAL, NULL);

	if (fp == INVALID_HANDLE_VALUE)
		return match;

	if ((lowSize = GetFileSize(fp, &highSize)) == INVALID_FILE_SIZE)
	{
		WLog_ERR(TAG, "GetFileSize(%s) returned %s [0x%08"PRIX32"]",
		         certificate_store->legacy_file, strerror(errno), GetLastError());
		CloseHandle(fp);
		return match;
	}

	size = (UINT64)lowSize | ((UINT64)highSize << 32);

	if (size < 1)
	{
		CloseHandle(fp);
		return match;
	}

	mdata = (char*) malloc(size + 2);

	if (!mdata)
	{
		CloseHandle(fp);
		return match;
	}

	data = mdata;

	if (!ReadFile(fp, data, size, &read, NULL) || (read != size))
	{
		free(data);
		CloseHandle(fp);
		return match;
	}

	CloseHandle(fp);
	data[size] = '\n';
	data[size + 1] = '\0';
	pline = StrSep(&data, "\r\n");

	while (pline != NULL)
	{
		length = strlen(pline);

		if (length > 0)
		{
			if (certificate_line_is_comment(pline, length))
			{
			}
			else if (!certificate_split_line(pline, &hostname, &port,
			                                 &subject, &issuer, &fingerprint))
				WLog_WARN(TAG, "Invalid %s entry %s!",
				          certificate_known_hosts_file, pline);
			else if (strcmp(pline, certificate_data->hostname) == 0)
			{
				int outLen;

				if (port == certificate_data->port)
				{
					found = TRUE;

					if (fingerprint)
					{
						match = (strcmp(certificate_data->fingerprint, fingerprint) == 0) ? 0 : -1;

						if (fprint)
							*fprint = _strdup(fingerprint);
					}

					if (subject && psubject)
						crypto_base64_decode(subject, strlen(subject), (BYTE**)psubject, &outLen);

					if (issuer && pissuer)
						crypto_base64_decode(issuer, strlen(issuer), (BYTE**)pissuer, &outLen);

					break;
				}
			}
		}

		pline = StrSep(&data, "\r\n");
	}

	free(mdata);

	if ((match != 0) && !found)
		match = certificate_data_match_legacy(certificate_store, certificate_data);

	return match;
}

BOOL certificate_get_stored_data(rdpCertificateStore* certificate_store,
                                 rdpCertificateData* certificate_data,
                                 char** subject, char** issuer,
                                 char** fingerprint)
{
	int rc = certificate_data_match_raw(certificate_store, certificate_data,
	                                    subject, issuer, fingerprint);

	if ((rc == 0) || (rc == -1))
		return TRUE;

	return FALSE;
}

int certificate_data_match(rdpCertificateStore* certificate_store,
                           rdpCertificateData* certificate_data)
{
	return certificate_data_match_raw(certificate_store, certificate_data,
	                                  NULL, NULL, NULL);
}

BOOL certificate_data_replace(rdpCertificateStore* certificate_store,
                              rdpCertificateData* certificate_data)
{
	HANDLE fp;
	BOOL rc = FALSE;
	size_t length;
	char* data;
	char* sdata;
	char* pline;
	UINT64 size;
	DWORD read, written;
	DWORD lowSize, highSize;
	/* Assure POSIX style paths, CreateFile expects either '/' or '\\' */
	PathCchConvertStyleA(certificate_store->file, strlen(certificate_store->file), PATH_STYLE_UNIX);
	fp = CreateFileA(certificate_store->file, GENERIC_READ | GENERIC_WRITE, 0,
	                 NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

	if (fp == INVALID_HANDLE_VALUE)
		return FALSE;

	if ((lowSize = GetFileSize(fp, &highSize)) == INVALID_FILE_SIZE)
	{
		WLog_ERR(TAG, "GetFileSize(%s) returned %s [0x%08"PRIX32"]",
		         certificate_store->legacy_file, strerror(errno), GetLastError());
		CloseHandle(fp);
		return FALSE;
	}

	size = (UINT64)lowSize | ((UINT64)highSize << 32);

	if (size < 1)
	{
		CloseHandle(fp);
		return FALSE;
	}

	data = (char*) malloc(size + 2);

	if (!data)
	{
		CloseHandle(fp);
		return FALSE;
	}

	if (!ReadFile(fp, data, size, &read, NULL) || (read != size))
	{
		free(data);
		CloseHandle(fp);
		return FALSE;
	}

	if (SetFilePointer(fp, 0, NULL, FILE_BEGIN) == INVALID_SET_FILE_POINTER)
	{
		WLog_ERR(TAG, "SetFilePointer(%s) returned %s [0x%08"PRIX32"]",
		         certificate_store->file, strerror(errno), GetLastError());
		free(data);
		CloseHandle(fp);
		return FALSE;
	}

	if (!SetEndOfFile(fp))
	{
		WLog_ERR(TAG, "SetEndOfFile(%s) returned %s [0x%08"PRIX32"]",
		         certificate_store->file, strerror(errno), GetLastError());
		free(data);
		CloseHandle(fp);
		return FALSE;
	}

	/* Write the file back out, with appropriate fingerprint substitutions */
	data[size] = '\n';
	data[size + 1] = '\0';
	sdata = data;
	pline = StrSep(&sdata, "\r\n");

	while (pline != NULL)
	{
		length = strlen(pline);

		if (length > 0)
		{
			UINT16 port = 0;
			char* hostname = NULL;
			char* fingerprint = NULL;
			char* subject = NULL;
			char* issuer = NULL;
			char* tdata;

			if (certificate_line_is_comment(pline, length))
			{
			}
			else if (!certificate_split_line(pline, &hostname, &port, &subject, &issuer, &fingerprint))
				WLog_WARN(TAG, "Skipping invalid %s entry %s!",
				          certificate_known_hosts_file, pline);
			else
			{
				/* If this is the replaced hostname, use the updated fingerprint. */
				if ((strcmp(hostname, certificate_data->hostname) == 0) &&
				    (port == certificate_data->port))
				{
					fingerprint = certificate_data->fingerprint;
					rc = TRUE;
				}

				size = _snprintf(NULL, 0, "%s %"PRIu16" %s %s %s\n", hostname, port, fingerprint, subject, issuer);
				tdata = malloc(size + 1);

				if (!tdata)
				{
					WLog_ERR(TAG, "malloc(%s) returned %s [0x%08X]",
					         certificate_store->file, strerror(errno), errno);
					free(data);
					CloseHandle(fp);
					return FALSE;
				}

				if (_snprintf(tdata, size + 1, "%s %"PRIu16" %s %s %s\n", hostname, port, fingerprint, subject,
				              issuer) != size)
				{
					WLog_ERR(TAG, "_snprintf(%s) returned %s [0x%08X]",
					         certificate_store->file, strerror(errno), errno);
					free(tdata);
					free(data);
					CloseHandle(fp);
					return FALSE;
				}

				if (!WriteFile(fp, tdata, size, &written, NULL) || (written != size))
				{
					WLog_ERR(TAG, "WriteFile(%s) returned %s [0x%08X]",
					         certificate_store->file, strerror(errno), errno);
					free(tdata);
					free(data);
					CloseHandle(fp);
					return FALSE;
				}

				free(tdata);
			}
		}

		pline = StrSep(&sdata, "\r\n");
	}

	CloseHandle(fp);
	free(data);
	return rc;
}

BOOL certificate_split_line(char* line, char** host, UINT16* port, char** subject,
                            char** issuer, char** fingerprint)
{
	char* cur;
	size_t length = strlen(line);

	if (length <= 0)
		return FALSE;

	cur = StrSep(&line, " \t");

	if (!cur)
		return FALSE;

	*host = cur;
	cur = StrSep(&line, " \t");

	if (!cur)
		return FALSE;

	if (sscanf(cur, "%hu", port) != 1)
		return FALSE;

	cur = StrSep(&line, " \t");

	if (!cur)
		return FALSE;

	*fingerprint = cur;
	cur = StrSep(&line, " \t");

	if (!cur)
		return FALSE;

	*subject = cur;
	cur = StrSep(&line, " \t");

	if (!cur)
		return FALSE;

	*issuer = cur;
	return TRUE;
}

BOOL certificate_data_print(rdpCertificateStore* certificate_store,
                            rdpCertificateData* certificate_data)
{
	HANDLE fp;
	char* tdata;
	UINT64 size;
	DWORD written;
	/* reopen in append mode */
	/* Assure POSIX style paths, CreateFile expects either '/' or '\\' */
	PathCchConvertStyleA(certificate_store->file, strlen(certificate_store->file), PATH_STYLE_UNIX);
	fp = CreateFileA(certificate_store->file, GENERIC_WRITE, 0,
	                 NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

	if (fp == INVALID_HANDLE_VALUE)
		return FALSE;

	if (SetFilePointer(fp, 0, NULL, FILE_END) == INVALID_SET_FILE_POINTER)
	{
		WLog_ERR(TAG, "SetFilePointer(%s) returned %s [0x%08"PRIX32"]",
		         certificate_store->file, strerror(errno), GetLastError());
		CloseHandle(fp);
		return FALSE;
	}

	size = _snprintf(NULL, 0, "%s %"PRIu16" %s %s %s\n", certificate_data->hostname,
	                 certificate_data->port,
	                 certificate_data->fingerprint, certificate_data->subject,
	                 certificate_data->issuer);
	tdata = malloc(size + 1);

	if (!tdata)
	{
		WLog_ERR(TAG, "malloc(%s) returned %s [0x%08X]",
		         certificate_store->file, strerror(errno), errno);
		CloseHandle(fp);
		return FALSE;
	}

	if (_snprintf(tdata, size + 1, "%s %"PRIu16" %s %s %s\n", certificate_data->hostname,
	              certificate_data->port,
	              certificate_data->fingerprint, certificate_data->subject,
	              certificate_data->issuer) != size)
	{
		WLog_ERR(TAG, "_snprintf(%s) returned %s [0x%08X]",
		         certificate_store->file, strerror(errno), errno);
		free(tdata);
		CloseHandle(fp);
		return FALSE;
	}

	if (!WriteFile(fp, tdata, size, &written, NULL) || (written != size))
	{
		WLog_ERR(TAG, "WriteFile(%s) returned %s [0x%08X]",
		         certificate_store->file, strerror(errno), errno);
		free(tdata);
		CloseHandle(fp);
		return FALSE;
	}

	free(tdata);
	CloseHandle(fp);
	return TRUE;
}

rdpCertificateData* certificate_data_new(const char* hostname, UINT16 port, const char* subject,
        const char* issuer, const char* fingerprint)
{
	size_t i;
	rdpCertificateData* certdata;

	if (!hostname)
		return NULL;

	if (!fingerprint)
		return NULL;

	certdata = (rdpCertificateData*)calloc(1, sizeof(rdpCertificateData));

	if (!certdata)
		return NULL;

	certdata->port = port;
	certdata->hostname = _strdup(hostname);

	if (subject)
		certdata->subject = crypto_base64_encode((BYTE*)subject, strlen(subject));
	else
		certdata->subject = crypto_base64_encode((BYTE*)"", 0);

	if (issuer)
		certdata->issuer = crypto_base64_encode((BYTE*)issuer, strlen(issuer));
	else
		certdata->issuer = crypto_base64_encode((BYTE*)"", 0);

	certdata->fingerprint = _strdup(fingerprint);

	if (!certdata->hostname || !certdata->subject ||
	    !certdata->issuer || !certdata->fingerprint)
		goto fail;

	for (i = 0; i < strlen(hostname); i++)
		certdata->hostname[i] = tolower(certdata->hostname[i]);

	return certdata;
fail:
	free(certdata->hostname);
	free(certdata->subject);
	free(certdata->issuer);
	free(certdata->fingerprint);
	free(certdata);
	return NULL;
}

void certificate_data_free(rdpCertificateData* certificate_data)
{
	if (certificate_data != NULL)
	{
		free(certificate_data->hostname);
		free(certificate_data->subject);
		free(certificate_data->issuer);
		free(certificate_data->fingerprint);
		free(certificate_data);
	}
}

rdpCertificateStore* certificate_store_new(rdpSettings* settings)
{
	rdpCertificateStore* certificate_store;
	certificate_store = (rdpCertificateStore*) calloc(1, sizeof(rdpCertificateStore));

	if (!certificate_store)
		return NULL;

	certificate_store->settings = settings;

	if (!certificate_store_init(certificate_store))
	{
		free(certificate_store);
		return NULL;
	}

	return certificate_store;
}

void certificate_store_free(rdpCertificateStore* certstore)
{
	if (certstore != NULL)
	{
		free(certstore->path);
		free(certstore->file);
		free(certstore->legacy_file);
		free(certstore);
	}
}