mirror of
https://github.com/norohind/hans.git
synced 2025-04-13 21:27:14 +03:00
125 lines
3.6 KiB
C++
125 lines
3.6 KiB
C++
/*
|
|
* Hans - IP over ICMP
|
|
* Copyright (C) 2009 Friedrich Schöller <hans@schoeller.se>
|
|
*
|
|
* 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 3 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, see <http://www.gnu.org/licenses/>.
|
|
*
|
|
*/
|
|
|
|
#include "echo.h"
|
|
#include "exception.h"
|
|
|
|
#include <sys/socket.h>
|
|
#include <sys/types.h>
|
|
#include <netinet/in_systm.h>
|
|
#include <netinet/in.h>
|
|
#include <netinet/ip.h>
|
|
#include <arpa/inet.h>
|
|
#include <unistd.h>
|
|
#include <errno.h>
|
|
#include <syslog.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <sys/types.h>
|
|
|
|
typedef ip IpHeader;
|
|
|
|
Echo::Echo(int maxPayloadSize)
|
|
{
|
|
fd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP);
|
|
if (fd == -1)
|
|
throw Exception("creating icmp socket", true);
|
|
|
|
bufferSize = maxPayloadSize + headerSize();
|
|
sendBuffer = new char[bufferSize];
|
|
receiveBuffer = new char[bufferSize];
|
|
}
|
|
|
|
Echo::~Echo()
|
|
{
|
|
close(fd);
|
|
|
|
delete[] sendBuffer;
|
|
delete[] receiveBuffer;
|
|
}
|
|
|
|
int Echo::headerSize()
|
|
{
|
|
return sizeof(IpHeader) + sizeof(EchoHeader);
|
|
}
|
|
|
|
void Echo::send(int payloadLength, uint32_t realIp, bool reply, uint16_t id, uint16_t seq)
|
|
{
|
|
struct sockaddr_in target;
|
|
target.sin_family = AF_INET;
|
|
target.sin_addr.s_addr = htonl(realIp);
|
|
|
|
if (payloadLength + sizeof(IpHeader) + sizeof(EchoHeader) > bufferSize)
|
|
throw Exception("packet too big");
|
|
|
|
EchoHeader *header = (EchoHeader *)(sendBuffer + sizeof(IpHeader));
|
|
header->type = reply ? 0: 8;
|
|
header->code = 0;
|
|
header->id = htons(id);
|
|
header->seq = htons(seq);
|
|
header->chksum = 0;
|
|
header->chksum = icmpChecksum(sendBuffer + sizeof(IpHeader), payloadLength + sizeof(EchoHeader));
|
|
|
|
int result = sendto(fd, sendBuffer + sizeof(IpHeader), payloadLength + sizeof(EchoHeader), 0, (struct sockaddr *)&target, sizeof(struct sockaddr_in));
|
|
if (result == -1)
|
|
syslog(LOG_ERR, "error sending icmp packet: %s", strerror(errno));
|
|
}
|
|
|
|
int Echo::receive(uint32_t &realIp, bool &reply, uint16_t &id, uint16_t &seq)
|
|
{
|
|
struct sockaddr_in source;
|
|
int source_addr_len = sizeof(struct sockaddr_in);
|
|
|
|
int dataLength = recvfrom(fd, receiveBuffer, bufferSize, 0, (struct sockaddr *)&source, (socklen_t *)&source_addr_len);
|
|
if (dataLength == -1)
|
|
{
|
|
syslog(LOG_ERR, "error receiving icmp packet: %s", strerror(errno));
|
|
return -1;
|
|
}
|
|
|
|
if (dataLength < sizeof(IpHeader) + sizeof(EchoHeader))
|
|
return -1;
|
|
|
|
EchoHeader *header = (EchoHeader *)(receiveBuffer + sizeof(IpHeader));
|
|
if ((header->type != 0 && header->type != 8) || header->code != 0)
|
|
return -1;
|
|
|
|
realIp = ntohl(source.sin_addr.s_addr);
|
|
reply = header->type == 0;
|
|
id = ntohs(header->id);
|
|
seq = ntohs(header->seq);
|
|
|
|
return dataLength - sizeof(IpHeader) - sizeof(EchoHeader);
|
|
}
|
|
|
|
uint16_t Echo::icmpChecksum(const char *data, int length)
|
|
{
|
|
uint16_t *data16 = (uint16_t *)data;
|
|
uint32_t sum = 0;
|
|
|
|
for (sum = 0; length > 1; length -= 2)
|
|
sum += *data16++;
|
|
if (length == 1)
|
|
sum += *(unsigned char *)data16;
|
|
|
|
sum = (sum >> 16) + (sum & 0xffff);
|
|
sum += (sum >> 16);
|
|
return ~sum;
|
|
}
|