/*
 * Copyright (c) 2019-2020 Job Snijders <job@sobornost.net>
 * Copyright (c) 2007-2019 Alexandre Snarskii <snar@snar.spb.ru>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "extern.h"
#include "sx_report.h"

int
sx_maxsockbuf(int s, int dir)
{
	int		optval = 0, voptval;
	int		hiconf = -1, loconf = -1;
	unsigned int	voptlen;
	int		phase = 0, iterations = 0;

	if (s < 0) {
		sx_report(SX_FATAL,"Unable to maximize sockbuf on invalid "
		    "socket %i\n", s);
		exit(1);
	}

	voptlen = sizeof(optval);

	if (getsockopt(s, SOL_SOCKET, dir, (void*)&optval, &voptlen) == -1) {
		sx_report(SX_ERROR,"initial getsockopt failed: %s\n",
		    strerror(errno));
		return -1;
	}

	for (;;) {
		iterations++;

		if (phase == 0)
			optval <<= 1;
		else {
			if (optval == (hiconf + loconf) / 2)
				break;
			optval = (hiconf + loconf) / 2;
		}

		if (setsockopt(s, SOL_SOCKET, dir, (void*)&optval,
		    sizeof(optval)) == -1) {

			if (phase == 0)
				phase = 1;

			hiconf = optval;

			continue;
		} else {
			loconf = optval;
		}

		voptlen = sizeof(voptval);

		if (getsockopt(s, SOL_SOCKET, dir, (void*)&voptval,
		    &voptlen) == -1) {
			sx_report(SX_ERROR,"getsockopt failed: %s\n",
			    strerror(errno));
			return -1;
		} else if (voptval < optval) {
			if (phase == 0) {
				phase = 1;
				optval >>= 1;
				continue;
			} else if (phase == 1) {
				phase = 2;
				optval -= 2048;
				continue;
			} else
				break;
		}
	}

	voptlen = sizeof(voptval);
	if (getsockopt(s, SOL_SOCKET, dir, (void*)&voptval,
	    &voptlen) == -1) {
		sx_report(SX_ERROR,"getsockopt(final stage) failed: %s\n",
		    strerror(errno));
		return -1;
	} else
		return voptval;
}