icinga2/base/netstring.cpp

/******************************************************************************
 * Icinga 2                                                                   *
 * Copyright (C) 2012 Icinga Development Team (http://www.icinga.org/)        *
 *                                                                            *
 * 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.                     *
 *                                                                            *
 * 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.                               *
 *                                                                            *
 * You should have received a copy of the GNU General Public License          *
 * along with this program; if not, write to the Free Software Foundation     *
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.             *
 ******************************************************************************/

#include "i2-base.h"

using namespace icinga;

/**
 * Reads data from an IOQueue in netstring format.
 *
 * @param fifo The IOQueue to read from.
 * @param[out] str The string that has been read from the FIFO.
 * @returns true if a complete string was read from the FIFO, false otherwise.
 * @exception invalid_argument The input stream is invalid.
 * @see https://github.com/PeterScott/netstring-c/blob/master/netstring.c
 */
bool Netstring::ReadStringFromIOQueue(IOQueue *queue, string *str)
{
	size_t buffer_length = queue->GetAvailableBytes();

	/* minimum netstring length is 3 */
	if (buffer_length < 3)
		return false;

	/* limit the number of bytes we're reading for the header */
	if (buffer_length > 16)
		buffer_length = 16;

	char *buffer = (char *)malloc(buffer_length);

	if (buffer == NULL && buffer_length > 0)
		throw_exception(bad_alloc());

	queue->Peek(buffer, buffer_length);

	/* no leading zeros allowed */
	if (buffer[0] == '0' && isdigit(buffer[1])) {
		free(buffer);
		throw_exception(invalid_argument("Invalid netstring (leading zero)"));
	}

	size_t len, i;

	len = 0;
	for (i = 0; i < buffer_length && isdigit(buffer[i]); i++) {
		/* length specifier must have at most 9 characters */
		if (i >= 9) {
			free(buffer);
			throw_exception(invalid_argument("Length specifier must not exceed 9 characters"));
		}

		len = len * 10 + (buffer[i] - '0');
	}

	buffer_length = queue->GetAvailableBytes();

	/* make sure the buffer is large enough */
	if (i + len + 1 >= buffer_length)
		return false;

	/* limit the number of bytes we're reading to this message */
	buffer_length = i + 1 + len + 1;

	char *new_buffer = (char *)realloc(buffer, buffer_length);

	if (new_buffer == NULL) {
		free(buffer);
		throw_exception(bad_alloc());
	}

	buffer = new_buffer;

	queue->Peek(buffer, buffer_length);

	/* check for the colon delimiter */
	if (buffer[i] != ':') {
		free(buffer);
		throw_exception(invalid_argument("Invalid Netstring (missing :)"));
	}

	/* check for the comma delimiter after the string */
	if (buffer[i + 1 + len] != ',') {
		free(buffer);
		throw_exception(invalid_argument("Invalid Netstring (missing ,)"));
	}

	*str = string(&buffer[i + 1], &buffer[i + 1 + len]);

	free(buffer);

	/* remove the data from the fifo */
	queue->Read(NULL, buffer_length);

	return true;
}

/**
 * Writes data into a FIFO using the netstring format.
 *
 * @param fifo The FIFO.
 * @param str The string that is to be written.
 */
void Netstring::WriteStringToIOQueue(IOQueue *queue, const string& str)
{
	stringstream prefixbuf;
	prefixbuf << str.size() << ":";

	string prefix = prefixbuf.str();
	queue->Write(prefix.c_str(), prefix.size());
	queue->Write(str.c_str(), str.size());
	queue->Write(",", 1);
}