TCP-IP-Router-Simulator/sender.c at master · flexarea/TCP-IP-Router-Simulator · GitHub

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/*
 * sender.c
 */

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdint.h>

#include "util.h"
#include "cs431vde.h"
#include "crc32.h"

	int
main(int argc, char *argv[])
{
	int fds[2];
	ssize_t frame_len;
	ssize_t rcv_frame_len;
	uint8_t rcv_frame[1600];

	char *data_as_hex;


	//ip packet encapsulated in ethernet frame (82 bytes)
	uint8_t frame[1600] = {
		0x12,0x9f,0x41,0x0d,0x0e,0x64, //destination address
		//0xff,0xff,0xff,0xff,0xff,0xff, //broadcasating
		0x12,0x9f,0x41,0x0d,0x0e,0x63, //source address
		0x08,0x00,                     //type (IP)
									   //----------IP
		0x45,                          //version and IHL
		0x00,                          //type of service
		0x00,0x44,                     //total length
		0x00,0x01,                     //identification
		0x00,0x00,                     //Flags and Fragment Offset
		0x01,0xFF,                     //TTL and Protocol (0x01 for ICMP)
		0x00,0x00,					   //4 bytes Header Checksum here
		0x01,0x02,0x01,0x02,            //Source address
		0x01,0x03,0x01,0x02,            //Destination address

		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	};

	int connect_to_remote_switch = 0;
	char *local_vde_cmd[] = {"vde_plug", "/home/entuyenabo/cs432/cs431/tmp/net1.vde", NULL};
	char *remote_vde_cmd[] = { "ssh", "pjohnson@weathertop.cs.middlebury.edu","/home/pjohnson/cs431/bin/vde_plug",NULL };
	char **vde_cmd = connect_to_remote_switch ? remote_vde_cmd : local_vde_cmd;

	if(connect_to_vde_switch(fds, vde_cmd) < 0) {
		printf("Could not connect to switch, exiting.\n");
		exit(1);
	}

	//memset(frame, '\xff', 64);

	//compute ip checksum
	uint16_t ip_checksum_ = ip_checksum(frame+14, 20);

	frame[24] = (ip_checksum_ >> 8) & 0xFF;
	frame[25] = ip_checksum_ & 0xFF;

	//compute cfs (82 for ip packet, 60 for arp)
	uint32_t crc = crc32(0, frame, 82);	//3rd param: dst_addr+src_addr+type+payload

	uint8_t *cfs_ptr = (uint8_t *)frame + 82; //
	memcpy(cfs_ptr, &crc, 4);
	frame_len = 86;

	printf("sending frame, length %ld\n", frame_len);
	send_ethernet_frame(fds[1], frame, frame_len);

	/* If the program exits immediately after sending its frames, there is a
	 * possibility the frames won't actually be delivered.  If, for example,
	 * the "remote_vde_cmd" above is used, the user might not even finish
	 * typing their password (which is accepted by a child process) before
	 * this process terminates, which would result in send frames not actually
	 * arriving.  Therefore, we pause and let the user manually end this
	 * process.
	 * */

	printf("Press Control-C to terminate sender.\n");
	//pause();

	while((rcv_frame_len = receive_ethernet_frame(fds[0], rcv_frame)) > 0) {
		data_as_hex = binary_to_hex(rcv_frame, rcv_frame_len);
		printf("received frame, length %ld:\n", rcv_frame_len);
		puts(data_as_hex);
		free(data_as_hex);
	}

	if(rcv_frame_len < 0) {
		perror("read");
		exit(1);
	}
	return 0;
}