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/*
 * Copyright (C) 2013 Tobias Brunner
 * Copyright (C) 2007 Martin Willi
 * HSR Hochschule fuer Technik Rapperswil
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 */

#include "mysql_database.h"

#define _GNU_SOURCE
#include <string.h>
#include <mysql.h>

#include <utils/debug.h>
#include <utils/chunk.h>
#include <threading/thread_value.h>
#include <threading/mutex.h>
#include <collections/linked_list.h>

/* Older mysql.h headers do not define it, but we need it. It is not returned
 * in in MySQL 4 by default, but by MySQL 5. To avoid this problem, we catch
 * it in all cases. */
#ifndef MYSQL_DATA_TRUNCATED
#define MYSQL_DATA_TRUNCATED 101
#endif

typedef struct private_mysql_database_t private_mysql_database_t;

/**
 * private data of mysql_database
 */
struct private_mysql_database_t {

	/**
	 * public functions
	 */
	mysql_database_t public;

	/**
	 * connection pool, contains conn_t
	 */
	linked_list_t *pool;

	/**
	 * thread-specific transaction, as transaction_t
	 */
	thread_value_t *transaction;

	/**
	 * mutex to lock pool
	 */
	mutex_t *mutex;

	/**
	 * hostname to connect to
	 */
	char *host;

	/**
	 * username to use
	 */
	char *username;

	/**
	 * password
	 */
	char *password;

	/**
	 * database name
	 */
	char *database;

	/**
	 * tcp port
	 */
	int port;
};

typedef struct conn_t conn_t;

/**
 * connection pool entry
 */
struct conn_t {

	/**
	 * MySQL database connection
	 */
	MYSQL *mysql;

	/**
	 * connection in use?
	 */
	bool in_use;
};

/**
 * database transaction
 */
typedef struct {

	/**
	 * Reference to the specific connection we started the transaction on
	 */
	conn_t *conn;

	/**
	 * Refcounter if transaction() is called multiple times
	 */
	refcount_t refs;

	/**
	 * TRUE if transaction was rolled back
	 */
	bool rollback;

} transaction_t;

/**
 * Release a mysql connection
 */
static void conn_release(private_mysql_database_t *this, conn_t *conn)
{
	/* do not release the connection while transactions are using it */
	if (!this->transaction->get(this->transaction))
	{
		this->mutex->lock(this->mutex);
		conn->in_use = FALSE;
		this->mutex->unlock(this->mutex);
	}
}

/**
 * Destroy a transaction and release the connection
 */
static void transaction_destroy(private_mysql_database_t *this,
								transaction_t *trans)
{
	conn_release(this, trans->conn);
	free(trans);
}

/**
 * thread specific initialization flag
 */
thread_value_t *initialized;

/**
 * Initialize a thread for mysql usage
 */
static void thread_initialize()
{
	if (initialized->get(initialized) == NULL)
	{
		initialized->set(initialized, (void*)TRUE);
		mysql_thread_init();
	}
}

/**
 * mysql library initialization function
 */
bool mysql_database_init()
{
	if (mysql_library_init(0, NULL, NULL))
	{
		return FALSE;
	}
	initialized = thread_value_create((thread_cleanup_t)mysql_thread_end);
	return TRUE;
}

/**
 * mysql library cleanup function
 */
void mysql_database_deinit()
{
	initialized->destroy(initialized);
	mysql_thread_end();
	mysql_library_end();
}

/**
 * Destroy a mysql connection
 */
static void conn_destroy(conn_t *this)
{
	mysql_close(this->mysql);
	free(this);
}

/**
 * Acquire/Reuse a mysql connection
 */
static conn_t *conn_get(private_mysql_database_t *this, transaction_t **trans)
{
	conn_t *current, *found = NULL;
	enumerator_t *enumerator;
	transaction_t *transaction;

	thread_initialize();

	transaction = this->transaction->get(this->transaction);
	if (transaction)
	{
		if (trans)
		{
			*trans = transaction;
		}
		return transaction->conn;
	}

	while (TRUE)
	{
		this->mutex->lock(this->mutex);
		enumerator = this->pool->create_enumerator(this->pool);
		while (enumerator->enumerate(enumerator, &current))
		{
			if (!current->in_use)
			{
				found = current;
				found->in_use = TRUE;
				break;
			}
		}
		enumerator->destroy(enumerator);
		this->mutex->unlock(this->mutex);
		if (found)
		{	/* check connection if found, release if ping fails */
			if (mysql_ping(found->mysql) == 0)
			{
				break;
			}
			this->mutex->lock(this->mutex);
			this->pool->remove(this->pool, found, NULL);
			this->mutex->unlock(this->mutex);
			conn_destroy(found);
			found = NULL;
			continue;
		}
		break;
	}
	if (found == NULL)
	{
		INIT(found,
			.in_use = TRUE,
			.mysql = mysql_init(NULL),
		);
		if (!mysql_real_connect(found->mysql, this->host, this->username,
								this->password, this->database, this->port,
								NULL, 0))
		{
			DBG1(DBG_LIB, "connecting to mysql://%s:***@%s:%d/%s failed: %s",
				 this->username, this->host, this->port, this->database,
				 mysql_error(found->mysql));
			conn_destroy(found);
			found = NULL;
		}
		else
		{
			this->mutex->lock(this->mutex);
			this->pool->insert_last(this->pool, found);
			DBG2(DBG_LIB, "increased MySQL connection pool size to %d",
				 this->pool->get_count(this->pool));
			this->mutex->unlock(this->mutex);
		}
	}
	return found;
}

/**
 * Create and run a MySQL stmt using a sql string and args
 */
static MYSQL_STMT* run(MYSQL *mysql, char *sql, va_list *args)
{
	MYSQL_STMT *stmt;
	int params;

	stmt = mysql_stmt_init(mysql);
	if (stmt == NULL)
	{
		DBG1(DBG_LIB, "creating MySQL statement failed: %s",
			 mysql_error(mysql));
		return NULL;
	}
	if (mysql_stmt_prepare(stmt, sql, strlen(sql)))
	{
		DBG1(DBG_LIB, "preparing MySQL statement failed: %s",
			 mysql_stmt_error(stmt));
		mysql_stmt_close(stmt);
		return NULL;
	}
	params = mysql_stmt_param_count(stmt);
	if (params > 0)
	{
		int i;
		MYSQL_BIND *bind;

		bind = alloca(sizeof(MYSQL_BIND) * params);
		memset(bind, 0, sizeof(MYSQL_BIND) * params);

		for (i = 0; i < params; i++)
		{
			switch (va_arg(*args, db_type_t))
			{
				case DB_INT:
				{
					bind[i].buffer_type = MYSQL_TYPE_LONG;
					bind[i].buffer = (char*)alloca(sizeof(int));
					*(int*)bind[i].buffer = va_arg(*args, int);
					bind[i].buffer_length = sizeof(int);
					break;
				}
				case DB_UINT:
				{
					bind[i].buffer_type = MYSQL_TYPE_LONG;
					bind[i].buffer = (char*)alloca(sizeof(u_int));
					*(u_int*)bind[i].buffer = va_arg(*args, u_int);
					bind[i].buffer_length = sizeof(u_int);
					bind[i].is_unsigned = TRUE;
					break;
				}
				case DB_TEXT:
				{
					bind[i].buffer_type = MYSQL_TYPE_STRING;;
					bind[i].buffer = va_arg(*args, char*);
					if (bind[i].buffer)
					{
						bind[i].buffer_length = strlen(bind[i].buffer);
					}
					break;
				}
				case DB_BLOB:
				{
					chunk_t chunk = va_arg(*args, chunk_t);
					bind[i].buffer_type = MYSQL_TYPE_BLOB;
					bind[i].buffer = chunk.ptr;
					bind[i].buffer_length = chunk.len;
					break;
				}
				case DB_DOUBLE:
				{
					bind[i].buffer_type = MYSQL_TYPE_DOUBLE;
					bind[i].buffer = (char*)alloca(sizeof(double));
					*(double*)bind[i].buffer = va_arg(*args, double);
					bind[i].buffer_length = sizeof(double);
					break;
				}
				case DB_NULL:
				{
					bind[i].buffer_type = MYSQL_TYPE_NULL;
					break;
				}
				default:
					DBG1(DBG_LIB, "invalid data type supplied");
					mysql_stmt_close(stmt);
					return NULL;
			}
		}
		if (mysql_stmt_bind_param(stmt, bind))
		{
			DBG1(DBG_LIB, "binding MySQL param failed: %s",
				 mysql_stmt_error(stmt));
			mysql_stmt_close(stmt);
			return NULL;
		}
	}
	if (mysql_stmt_execute(stmt))
	{
		DBG1(DBG_LIB, "executing MySQL statement failed: %s",
			 mysql_stmt_error(stmt));
		mysql_stmt_close(stmt);
		return NULL;
	}
	return stmt;
}

typedef struct {
	/** implements enumerator_t */
	enumerator_t public;
	/** mysql database */
	private_mysql_database_t *db;
	/** associated MySQL statement */
	MYSQL_STMT *stmt;
	/** result bindings */
	MYSQL_BIND *bind;
	/** pooled connection handle */
	conn_t *conn;
	/** value for INT, UINT, double */
	union {
		void *p_void;;
		int *p_int;
		u_int *p_uint;
		double *p_double;
	} val;
	/* length for TEXT and BLOB */
	unsigned long *length;
} mysql_enumerator_t;

METHOD(enumerator_t, mysql_enumerator_destroy, void,
	mysql_enumerator_t *this)
{
	int columns, i;

	columns = mysql_stmt_field_count(this->stmt);

	for (i = 0; i < columns; i++)
	{
		switch (this->bind[i].buffer_type)
		{
			case MYSQL_TYPE_STRING:
			case MYSQL_TYPE_BLOB:
			{
				free(this->bind[i].buffer);
				break;
			}
			default:
				break;
		}
	}
	mysql_stmt_close(this->stmt);
	conn_release(this->db, this->conn);
	free(this->bind);
	free(this->val.p_void);
	free(this->length);
	free(this);
}

METHOD(enumerator_t, mysql_enumerator_enumerate, bool,
	mysql_enumerator_t *this, va_list args)
{
	int i, columns;

	columns = mysql_stmt_field_count(this->stmt);

	/* free/reset data set of previous call */
	for (i = 0; i < columns; i++)
	{
		switch (this->bind[i].buffer_type)
		{
			case MYSQL_TYPE_STRING:
			case MYSQL_TYPE_BLOB:
			{
				free(this->bind[i].buffer);
				this->bind[i].buffer = NULL;
				this->bind[i].buffer_length = 0;
				this->bind[i].length = &this->length[i];
				this->length[i] = 0;
				break;
			}
			default:
				break;
		}
	}

	switch (mysql_stmt_fetch(this->stmt))
	{
		case 0:
		case MYSQL_DATA_TRUNCATED:
			break;
		case MYSQL_NO_DATA:
			return FALSE;
		default:
			DBG1(DBG_LIB, "fetching MySQL row failed: %s",
				 mysql_stmt_error(this->stmt));
			return FALSE;
	}

	for (i = 0; i < columns; i++)
	{
		switch (this->bind[i].buffer_type)
		{
			case MYSQL_TYPE_LONG:
			{
				if (this->bind[i].is_unsigned)
				{
					u_int *value = va_arg(args, u_int*);
					*value = this->val.p_uint[i];
				}
				else
				{
					int *value = va_arg(args, int*);
					*value = this->val.p_int[i];
				}
				break;
			}
			case MYSQL_TYPE_STRING:
			{
				char **value = va_arg(args, char**);
				this->bind[i].buffer = malloc(this->length[i]+1);
				this->bind[i].buffer_length = this->length[i];
				*value = this->bind[i].buffer;
				mysql_stmt_fetch_column(this->stmt, &this->bind[i], i, 0);
				((char*)this->bind[i].buffer)[this->length[i]] = '\0';
				break;
			}
			case MYSQL_TYPE_BLOB:
			{
				chunk_t *value = va_arg(args, chunk_t*);
				this->bind[i].buffer = malloc(this->length[i]);
				this->bind[i].buffer_length = this->length[i];
				value->ptr = this->bind[i].buffer;
				value->len = this->length[i];
				mysql_stmt_fetch_column(this->stmt, &this->bind[i], i, 0);
				break;
			}
			case MYSQL_TYPE_DOUBLE:
			{
				double *value = va_arg(args, double*);
				*value = this->val.p_double[i];
				break;
			}
			default:
				break;
		}
	}
	return TRUE;
}

METHOD(database_t, query, enumerator_t*,
	private_mysql_database_t *this, char *sql, ...)
{
	MYSQL_STMT *stmt;
	va_list args;
	mysql_enumerator_t *enumerator = NULL;
	conn_t *conn;

	conn = conn_get(this, NULL);
	if (!conn)
	{
		return NULL;
	}

	va_start(args, sql);
	stmt = run(conn->mysql, sql, &args);
	if (stmt)
	{
		int columns, i;

		INIT(enumerator,
			.public = {
				.enumerate = enumerator_enumerate_default,
				.venumerate = _mysql_enumerator_enumerate,
				.destroy = _mysql_enumerator_destroy,
			},
			.db = this,
			.stmt = stmt,
			.conn = conn,
		);
		columns = mysql_stmt_field_count(stmt);
		enumerator->bind = calloc(columns, sizeof(MYSQL_BIND));
		enumerator->length = calloc(columns, sizeof(unsigned long));
		enumerator->val.p_void = calloc(columns, sizeof(enumerator->val));
		for (i = 0; i < columns; i++)
		{
			switch (va_arg(args, db_type_t))
			{
				case DB_INT:
				{
					enumerator->bind[i].buffer_type = MYSQL_TYPE_LONG;
					enumerator->bind[i].buffer = (char*)&enumerator->val.p_int[i];
					break;
				}
				case DB_UINT:
				{
					enumerator->bind[i].buffer_type = MYSQL_TYPE_LONG;
					enumerator->bind[i].buffer = (char*)&enumerator->val.p_uint[i];
					enumerator->bind[i].is_unsigned = TRUE;
					break;
				}
				case DB_TEXT:
				{
					enumerator->bind[i].buffer_type = MYSQL_TYPE_STRING;
					enumerator->bind[i].length = &enumerator->length[i];
					break;
				}
				case DB_BLOB:
				{
					enumerator->bind[i].buffer_type = MYSQL_TYPE_BLOB;
					enumerator->bind[i].length = &enumerator->length[i];
					break;
				}
				case DB_DOUBLE:
				{
					enumerator->bind[i].buffer_type = MYSQL_TYPE_DOUBLE;
					enumerator->bind[i].buffer = (char*)&enumerator->val.p_double[i];
					break;
				}
				default:
					DBG1(DBG_LIB, "invalid result data type supplied");
					mysql_enumerator_destroy(enumerator);
					va_end(args);
					return NULL;
			}
		}
		if (mysql_stmt_bind_result(stmt, enumerator->bind))
		{
			DBG1(DBG_LIB, "binding MySQL result failed: %s",
				 mysql_stmt_error(stmt));
			mysql_enumerator_destroy(enumerator);
			enumerator = NULL;
		}
	}
	else
	{
		conn_release(this, conn);
	}
	va_end(args);
	return (enumerator_t*)enumerator;
}

METHOD(database_t, execute, int,
	private_mysql_database_t *this, int *rowid, char *sql, ...)
{
	MYSQL_STMT *stmt;
	va_list args;
	conn_t *conn;
	int affected = -1;

	conn = conn_get(this, NULL);
	if (!conn)
	{
		return -1;
	}
	va_start(args, sql);
	stmt = run(conn->mysql, sql, &args);
	if (stmt)
	{
		if (rowid)
		{
			*rowid = mysql_stmt_insert_id(stmt);
		}
		affected = mysql_stmt_affected_rows(stmt);
		mysql_stmt_close(stmt);
	}
	va_end(args);
	conn_release(this, conn);
	return affected;
}

METHOD(database_t, transaction, bool,
	private_mysql_database_t *this, bool serializable)
{
	transaction_t *trans = NULL;
	conn_t *conn;

	conn = conn_get(this, &trans);
	if (!conn)
	{
		return FALSE;
	}
	else if (trans)
	{
		ref_get(&trans->refs);
		return TRUE;
	}
	/* these statements are not supported in prepared statements that are used
	 * by the execute() method */
	if (serializable)
	{
		if (mysql_query(conn->mysql,
						"SET TRANSACTION ISOLATION LEVEL SERIALIZABLE") != 0)
		{
			DBG1(DBG_LIB, "starting transaction failed: %s",
				 mysql_error(conn->mysql));
			conn_release(this, conn);
			return FALSE;
		}
	}
	if (mysql_query(conn->mysql, "START TRANSACTION") != 0)
	{
		DBG1(DBG_LIB, "starting transaction failed: %s",
			 mysql_error(conn->mysql));
		conn_release(this, conn);
		return FALSE;
	}
	INIT(trans,
		.conn = conn,
		.refs = 1,
	);
	this->transaction->set(this->transaction, trans);
	return TRUE;
}

/**
 * Finalize a transaction depending on the reference count and if it should be
 * rolled back.
 */
static bool finalize_transaction(private_mysql_database_t *this,
								 bool rollback)
{
	transaction_t *trans;
	char *command = "COMMIT";
	bool success;

	trans = this->transaction->get(this->transaction);
	if (!trans)
	{
		DBG1(DBG_LIB, "no database transaction found");
		return FALSE;
	}
	/* set flag, can't be unset */
	trans->rollback |= rollback;

	if (ref_put(&trans->refs))
	{
		if (trans->rollback)
		{
			command = "ROLLBACK";
		}
		success = mysql_query(trans->conn->mysql, command) == 0;

		this->transaction->set(this->transaction, NULL);
		transaction_destroy(this, trans);
		return success;
	}
	return TRUE;
}

METHOD(database_t, commit_, bool,
	private_mysql_database_t *this)
{
	return finalize_transaction(this, FALSE);
}

METHOD(database_t, rollback, bool,
	private_mysql_database_t *this)
{
	return finalize_transaction(this, TRUE);
}

METHOD(database_t, get_driver,db_driver_t,
	private_mysql_database_t *this)
{
	return DB_MYSQL;
}

METHOD(database_t, destroy, void,
	private_mysql_database_t *this)
{
	this->transaction->destroy(this->transaction);
	this->pool->destroy_function(this->pool, (void*)conn_destroy);
	this->mutex->destroy(this->mutex);
	free(this->host);
	free(this->username);
	free(this->password);
	free(this->database);
	free(this);
}

static bool parse_uri(private_mysql_database_t *this, char *uri)
{
	char *username, *password, *host, *port = "0", *database, *pos;

	/**
	 * parse mysql://username:pass@host:port/database uri
	 */
	username = strdup(uri + 8);
	pos = strchr(username, ':');
	if (pos)
	{
		*pos = '\0';
		password = pos + 1;
		pos = strrchr(password, '@');
		if (pos)
		{
			*pos = '\0';
			host = pos + 1;
			pos = strrchr(host, ':');
			if (pos)
			{
				*pos = '\0';
				port = pos + 1;
				pos = strchr(port, '/');
			}
			else
			{
				pos = strchr(host, '/');
			}
			if (pos)
			{
				*pos = '\0';
				database = pos + 1;

				this->host = strdup(host);
				this->username = strdup(username);
				this->password = strdup(password);
				this->database = strdup(database);
				this->port = atoi(port);
				free(username);
				return TRUE;
			}
		}
	}
	free(username);
	DBG1(DBG_LIB, "parsing MySQL database uri '%s' failed", uri);
	return FALSE;
}


/*
 * see header file
 */
mysql_database_t *mysql_database_create(char *uri)
{
	conn_t *conn;
	private_mysql_database_t *this;

	if (!strpfx(uri, "mysql://"))
	{
		return NULL;
	}

	INIT(this,
		.public = {
			.db = {
				.query = _query,
				.execute = _execute,
				.transaction = _transaction,
				.commit = _commit_,
				.rollback = _rollback,
				.get_driver = _get_driver,
				.destroy = _destroy,
			},
		},
	);

	if (!parse_uri(this, uri))
	{
		free(this);
		return NULL;
	}
	this->mutex = mutex_create(MUTEX_TYPE_DEFAULT);
	this->pool = linked_list_create();
	this->transaction = thread_value_create(NULL);

	/* check connectivity */
	conn = conn_get(this, NULL);
	if (!conn)
	{
		destroy(this);
		return NULL;
	}
	conn_release(this, conn);
	return &this->public;
}