/*-
 * Public Domain 2014-2015 MongoDB, Inc.
 * Public Domain 2008-2014 WiredTiger, Inc.
 *
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * ex_encrypt.c
 * 	demonstrates how to use the encryption API.
 */
#include <ctype.h>
#include <errno.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifndef _WIN32
#include <unistd.h>
#else
#include "windows_shim.h"
#endif

#include <wiredtiger.h>
#include <wiredtiger_ext.h>

#ifdef _WIN32
/*
 * Explicitly export this function so it is visible when loading extensions.
 */
__declspec(dllexport)
#endif
int add_my_encryptors(WT_CONNECTION *connection);

static const char *home = NULL;

#define	SYS_KEYID	"system"
#define	SYS_PW		"system_password"
#define	USER1_KEYID	"user1"
#define	USER2_KEYID	"user2"
#define	USERBAD_KEYID	"userbad"

#define	ITEM_MATCHES(config_item, s) \
	(strlen(s) == (config_item).len && \
	 strncmp((config_item).str, s, (config_item).len) == 0)

/*! [encryption example callback implementation] */
typedef struct {
	WT_ENCRYPTOR encryptor;	/* Must come first */
	int rot_N;		/* rotN value */
	uint32_t num_calls;	/* Count of calls */
	char *keyid;		/* Saved keyid */
	char *password;		/* Saved password */
} MY_CRYPTO;

#define	CHKSUM_LEN	4
#define	IV_LEN		16

/*
 * make_cksum --
 *	This is where one would call a checksum function on the encrypted
 *	buffer.  Here we just put a constant value in it.
 */
static void
make_cksum(uint8_t *dst)
{
	int i;
	/*
	 * Assume array is big enough for the checksum.
	 */
	for (i = 0; i < CHKSUM_LEN; i++)
		dst[i] = 'C';
}

/*
 * make_iv --
 *	This is where one would generate the initialization vector.
 *	Here we just put a constant value in it.
 */
static void
make_iv(uint8_t *dst)
{
	int i;
	/*
	 * Assume array is big enough for the initialization vector.
	 */
	for (i = 0; i < IV_LEN; i++)
		dst[i] = 'I';
}

/*
 * Rotate encryption functions.
 */
/*
 * do_rotate --
 *	Perform rot-N on the buffer given.
 */
static void
do_rotate(char *buf, size_t len, int rotn)
{
	uint32_t i;
	/*
	 * Now rotate
	 */
	for (i = 0; i < len; i++)
		if (isalpha(buf[i])) {
			if (islower(buf[i]))
				buf[i] = ((buf[i] - 'a') + rotn) % 26 + 'a';
			else
				buf[i] = ((buf[i] - 'A') + rotn) % 26 + 'A';
		}
}

/*
 * rotate_decrypt --
 *	A simple rotate decryption.
 */
static int
rotate_decrypt(WT_ENCRYPTOR *encryptor, WT_SESSION *session,
    uint8_t *src, size_t src_len,
    uint8_t *dst, size_t dst_len,
    size_t *result_lenp)
{
	MY_CRYPTO *my_crypto = (MY_CRYPTO *)encryptor;
	size_t mylen;
	uint32_t i;

	(void)session;		/* Unused */
	++my_crypto->num_calls;

	if (src == NULL)
		return (0);
	/*
	 * Make sure it is big enough.
	 */
	mylen = src_len - (CHKSUM_LEN + IV_LEN);
	if (dst_len < mylen) {
		fprintf(stderr,
		    "Rotate: ENOMEM ERROR: dst_len %zu src_len %zu\n",
		    dst_len, src_len);
		return (ENOMEM);
	}

	/*
	 * !!! Most implementations would verify any needed
	 * checksum and initialize the IV here.
	 */
	/*
	 * Copy the encrypted data to the destination buffer and then
	 * decrypt the destination buffer in place.
	 */
	i = CHKSUM_LEN + IV_LEN;
	memcpy(&dst[0], &src[i], mylen);
	/*
	 * Call common rotate function on the text portion of the
	 * buffer.  Send in dst_len as the length of the text.
	 */
	/*
	 * !!! Most implementations would need the IV too.
	 */
	do_rotate((char *)dst, mylen, 26 - my_crypto->rot_N);
	*result_lenp = mylen;
	return (0);
}

/*
 * rotate_encrypt --
 *	A simple rotate encryption.
 */
static int
rotate_encrypt(WT_ENCRYPTOR *encryptor, WT_SESSION *session,
    uint8_t *src, size_t src_len,
    uint8_t *dst, size_t dst_len,
    size_t *result_lenp)
{
	MY_CRYPTO *my_crypto = (MY_CRYPTO *)encryptor;
	uint32_t i;

	(void)session;		/* Unused */
	++my_crypto->num_calls;

	if (src == NULL)
		return (0);
	if (dst_len < src_len + CHKSUM_LEN + IV_LEN)
		return (ENOMEM);

	i = CHKSUM_LEN + IV_LEN;
	/*
	 * Skip over space reserved for checksum and initialization
	 * vector.  Copy text into destination buffer then encrypt
	 * in place.
	 */
	memcpy(&dst[i], &src[0], src_len);
	/*
	 * Call common rotate function on the text portion of the
	 * destination buffer.  Send in src_len as the length of
	 * the text.
	 */
	do_rotate((char *)dst + i, src_len, my_crypto->rot_N);
	/*
	 * Checksum the encrypted buffer and add the IV.
	 */
	i = 0;
	make_cksum(&dst[i]);
	i += CHKSUM_LEN;
	make_iv(&dst[i]);
	*result_lenp = dst_len;
	return (0);
}

/*
 * rotate_sizing --
 *	A sizing example that returns the header size needed.
 */
static int
rotate_sizing(WT_ENCRYPTOR *encryptor, WT_SESSION *session,
    size_t *expansion_constantp)
{
	MY_CRYPTO *my_crypto = (MY_CRYPTO *)encryptor;

	(void)session;				/* Unused parameters */

	++my_crypto->num_calls;		/* Call count */

	*expansion_constantp = CHKSUM_LEN + IV_LEN;
	return (0);
}

/*
 * rotate_customize --
 *	The customize function creates a customized encryptor
 */
static int
rotate_customize(WT_ENCRYPTOR *encryptor, WT_SESSION *session,
    WT_CONFIG_ARG *encrypt_config, WT_ENCRYPTOR **customp)
{
	MY_CRYPTO *my_crypto;
	WT_CONFIG_ITEM keyid, secret;
	WT_EXTENSION_API *extapi;
	int ret;
	const MY_CRYPTO *orig_crypto;

	extapi = session->connection->get_extension_api(session->connection);

	orig_crypto = (const MY_CRYPTO *)encryptor;
	if ((my_crypto = calloc(1, sizeof(MY_CRYPTO))) == NULL) {
		ret = errno;
		goto err;
	}
	*my_crypto = *orig_crypto;
	my_crypto->keyid = my_crypto->password = NULL;

	/*
	 * Stash the keyid and the (optional) secret key
	 * from the configuration string.
	 */
	if ((ret = extapi->config_get(extapi, session, encrypt_config,
	    "keyid", &keyid)) == 0 && keyid.len != 0) {
		if ((my_crypto->keyid = malloc(keyid.len + 1)) == NULL) {
			ret = errno;
			goto err;
		}
		strncpy(my_crypto->keyid, keyid.str, keyid.len + 1);
		my_crypto->keyid[keyid.len] = '\0';
	}

	if ((ret = extapi->config_get(extapi, session, encrypt_config,
	    "secretkey", &secret)) == 0 && secret.len != 0) {
		if ((my_crypto->password = malloc(secret.len + 1)) == NULL) {
			ret = errno;
			goto err;
		}
		strncpy(my_crypto->password, secret.str, secret.len + 1);
		my_crypto->password[secret.len] = '\0';
	}
	/*
	 * Presumably we'd have some sophisticated key management
	 * here that maps the id onto a secret key.
	 */
	if (ITEM_MATCHES(keyid, "system")) {
		if (my_crypto->password == NULL ||
		    strcmp(my_crypto->password, SYS_PW) != 0) {
			ret = EPERM;
			goto err;
		}
		my_crypto->rot_N = 13;
	} else if (ITEM_MATCHES(keyid, USER1_KEYID))
		my_crypto->rot_N = 4;
	else if (ITEM_MATCHES(keyid, USER2_KEYID))
		my_crypto->rot_N = 19;
	else {
		ret = EINVAL;
		goto err;
	}

	++my_crypto->num_calls;		/* Call count */

	*customp = (WT_ENCRYPTOR *)my_crypto;
	return (0);

err:	free(my_crypto->keyid);
	free(my_crypto->password);
	free(my_crypto);
	return (ret);
}

/*
 * rotate_terminate --
 *	WiredTiger rotate encryption termination.
 */
static int
rotate_terminate(WT_ENCRYPTOR *encryptor, WT_SESSION *session)
{
	MY_CRYPTO *my_crypto = (MY_CRYPTO *)encryptor;

	(void)session;				/* Unused parameters */

	++my_crypto->num_calls;		/* Call count */

	/* Free the allocated memory. */
	free(my_crypto->password);
	my_crypto->password = NULL;

	free(my_crypto->keyid);
	my_crypto->keyid = NULL;

	free(encryptor);

	return (0);
}

/*
 * add_my_encryptors --
 *	A simple example of adding encryption callbacks.
 */
int
add_my_encryptors(WT_CONNECTION *connection)
{
	MY_CRYPTO *m;
	WT_ENCRYPTOR *wt;
	int ret;

	/*
	 * Initialize our top level encryptor.
	 */
	if ((m = calloc(1, sizeof(MY_CRYPTO))) == NULL)
		return (errno);
	wt = (WT_ENCRYPTOR *)&m->encryptor;
	wt->encrypt = rotate_encrypt;
	wt->decrypt = rotate_decrypt;
	wt->sizing = rotate_sizing;
	wt->customize = rotate_customize;
	wt->terminate = rotate_terminate;
	m->num_calls = 0;
	if ((ret = connection->add_encryptor(
	    connection, "rotn", (WT_ENCRYPTOR *)m, NULL)) != 0)
		return (ret);

	return (0);
}

/*
 * simple_walk_log --
 *	A simple walk of the write-ahead log.
 *	We wrote text messages into the log.  Print them.
 *	This verifies we're decrypting properly.
 */
static int
simple_walk_log(WT_SESSION *session)
{
	WT_CURSOR *cursor;
	WT_ITEM logrec_key, logrec_value;
	WT_LSN lsn;
	uint64_t txnid;
	uint32_t fileid, opcount, optype, rectype;
	int found, ret;

	ret = session->open_cursor(session, "log:", NULL, NULL, &cursor);

	found = 0;
	while ((ret = cursor->next(cursor)) == 0) {
		ret = cursor->get_key(cursor, &lsn.file, &lsn.offset, &opcount);
		ret = cursor->get_value(cursor, &txnid,
		    &rectype, &optype, &fileid, &logrec_key, &logrec_value);

		if (rectype == WT_LOGREC_MESSAGE) {
			found = 1;
			printf("Application Log Record: %s\n",
			    (char *)logrec_value.data);
		}
	}
	if (ret == WT_NOTFOUND)
		ret = 0;
	ret = cursor->close(cursor);
	if (found == 0) {
		fprintf(stderr, "Did not find log messages.\n");
		exit(EXIT_FAILURE);
	}
	return (ret);
}

#define	MAX_KEYS	20

#define	EXTENSION_NAME  "local=(entry=add_my_encryptors)"

#define	WT_OPEN_CONFIG_COMMON \
    "create,cache_size=100MB,extensions=[" EXTENSION_NAME "],"\
    "log=(archive=false,enabled=true)," \

#define	WT_OPEN_CONFIG_GOOD \
    WT_OPEN_CONFIG_COMMON \
    "encryption=(name=rotn,keyid=" SYS_KEYID ",secretkey=" SYS_PW ")"

#define	COMP_A	"AAAAAAAAAAAAAAAAAA"
#define	COMP_B	"BBBBBBBBBBBBBBBBBB"
#define	COMP_C	"CCCCCCCCCCCCCCCCCC"

int
main(void)
{
	WT_CONNECTION *conn;
	WT_CURSOR *c1, *c2, *nc;
	WT_SESSION *session;
	int i, ret;
	char keybuf[16], valbuf[16];
	char *key1, *key2, *key3, *val1, *val2, *val3;

	/*
	 * Create a clean test directory for this run of the test program if the
	 * environment variable isn't already set (as is done by make check).
	 */
	if (getenv("WIREDTIGER_HOME") == NULL) {
		home = "WT_HOME";
		ret = system("rm -rf WT_HOME && mkdir WT_HOME");
	} else
		home = NULL;

	ret = wiredtiger_open(home, NULL, WT_OPEN_CONFIG_GOOD, &conn);

	ret = conn->open_session(conn, NULL, NULL, &session);

	/*
	 * Write a log record that is larger than the base 128 bytes and
	 * also should compress well.
	 */
	ret = session->log_printf(session,
	    COMP_A COMP_B COMP_C COMP_A COMP_B COMP_C
	    COMP_A COMP_B COMP_C COMP_A COMP_B COMP_C
	    "The quick brown fox jumps over the lazy dog ");
	ret = simple_walk_log(session);

	/*
	 * Create and open some encrypted and not encrypted tables.
	 * Also use column store and compression for some tables.
	 */
	ret = session->create(session, "table:crypto1",
	    "encryption=(name=rotn,keyid=" USER1_KEYID"),"
	    "columns=(key0,value0),"
	    "key_format=S,value_format=S");
	ret = session->create(session, "index:crypto1:byvalue",
	    "encryption=(name=rotn,keyid=" USER1_KEYID"),"
	    "columns=(value0,key0)");
	ret = session->create(session, "table:crypto2",
	    "encryption=(name=rotn,keyid=" USER2_KEYID"),"
	    "key_format=S,value_format=S");
	ret = session->create(session, "table:nocrypto",
	    "key_format=S,value_format=S");

	/*
	 * Send in an unknown keyid.  WiredTiger will try to add in the
	 * new keyid, but the customize function above will return an
	 * error since it is unrecognized.
	 */
	ret = session->create(session, "table:cryptobad",
	    "encryption=(name=rotn,keyid=" USERBAD_KEYID"),"
	    "key_format=S,value_format=S");
	if (ret == 0) {
		fprintf(stderr, "Did not detect bad/unknown keyid error\n");
		exit(EXIT_FAILURE);
	}

	ret = session->open_cursor(session, "table:crypto1", NULL, NULL, &c1);
	ret = session->open_cursor(session, "table:crypto2", NULL, NULL, &c2);
	ret = session->open_cursor(session, "table:nocrypto", NULL, NULL, &nc);

	/* 
	 * Insert a set of keys and values.  Insert the same data into
	 * all tables so that we can verify they're all the same after
	 * we decrypt on read.
	 */
	for (i = 0; i < MAX_KEYS; i++) {
		snprintf(keybuf, sizeof(keybuf), "key%d", i);
		c1->set_key(c1, keybuf);
		c2->set_key(c2, keybuf);
		nc->set_key(nc, keybuf);

		snprintf(valbuf, sizeof(valbuf), "value%d", i);
		c1->set_value(c1, valbuf);
		c2->set_value(c2, valbuf);
		nc->set_value(nc, valbuf);

		ret = c1->insert(c1);
		ret = c2->insert(c2);
		ret = nc->insert(nc);
		if (i % 5 == 0)
			ret = session->log_printf(session,
			    "Wrote %d records", i);
	}
	ret = session->log_printf(session, "Done. Wrote %d total records", i);

	while (c1->next(c1) == 0) {
		ret = c1->get_key(c1, &key1);
		ret = c1->get_value(c1, &val1);

		printf("Read key %s; value %s\n", key1, val1);
	}
	ret = simple_walk_log(session);
	printf("CLOSE\n");
	ret = conn->close(conn, NULL);

	/*
	 * We want to close and reopen so that we recreate the cache
	 * by reading the data from disk, forcing decryption.
	 */
	printf("REOPEN and VERIFY encrypted data\n");

	ret = wiredtiger_open(home, NULL, WT_OPEN_CONFIG_GOOD, &conn);

	ret = conn->open_session(conn, NULL, NULL, &session);
	/*
	 * Verify we can read the encrypted log after restart.
	 */
	ret = simple_walk_log(session);
	ret = session->open_cursor(session, "table:crypto1", NULL, NULL, &c1);
	ret = session->open_cursor(session, "table:crypto2", NULL, NULL, &c2);
	ret = session->open_cursor(session, "table:nocrypto", NULL, NULL, &nc);

	/*
	 * Read the same data from each cursor.  All should be identical.
	 */
	while (c1->next(c1) == 0) {
		ret = c2->next(c2);
		ret = nc->next(nc);
		ret = c1->get_key(c1, &key1);
		ret = c1->get_value(c1, &val1);
		ret = c2->get_key(c2, &key2);
		ret = c2->get_value(c2, &val2);
		ret = nc->get_key(nc, &key3);
		ret = nc->get_value(nc, &val3);

		if (strcmp(key1, key2) != 0)
			fprintf(stderr, "Key1 %s and Key2 %s do not match\n",
			    key1, key2);
		if (strcmp(key1, key3) != 0)
			fprintf(stderr, "Key1 %s and Key3 %s do not match\n",
			    key1, key3);
		if (strcmp(key2, key3) != 0)
			fprintf(stderr, "Key2 %s and Key3 %s do not match\n",
			    key2, key3);
		if (strcmp(val1, val2) != 0)
			fprintf(stderr, "Val1 %s and Val2 %s do not match\n",
			    val1, val2);
		if (strcmp(val1, val3) != 0)
			fprintf(stderr, "Val1 %s and Val3 %s do not match\n",
			    val1, val3);
		if (strcmp(val2, val3) != 0)
			fprintf(stderr, "Val2 %s and Val3 %s do not match\n",
			    val2, val3);

		printf("Verified key %s; value %s\n", key1, val1);
	}
	ret = conn->close(conn, NULL);
	return (ret);
}
