udpplay.c

/*
abest: cheap udp packet
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

#define MAX_PACKET (0xffff - 29)
#define BUFSIZE 1024

int main(int argc, char *argv[])
{

	int sock, r;
	int z;
	int len;
	int port = 12345;
	struct sockaddr_in sAddr;
	struct sockaddr_in cAddr;
	struct hostent *he;
	char *buf;
	int buflen = 0;
	char *p;

	//ARGS
	if (argc < 2)
	{
		fprintf(stderr, "%s <host> <port>\n", argv[0]);
		exit(1);
	}
	port = atoi(argv[2]);

	he = gethostbyname(argv[1]);
	if (he == NULL)
	{
		fprintf(stderr, "%s: Unable to resolve host '%s' \n", argv[0], argv[1]);
		exit(1);
	}

	sAddr.sin_family = he->h_addrtype;
	memcpy((char *) &sAddr.sin_addr.s_addr, he->h_addr_list[0], he->h_length);
	sAddr.sin_port = htons(port);

	sock = socket(AF_INET, SOCK_DGRAM, 0);
	if (0 > sock)
	{
		fprintf(stderr, "%s: unable to open socket\n", argv[0]);
		exit(1);
	}

	cAddr.sin_family = AF_INET;
	cAddr.sin_addr.s_addr = htonl(INADDR_ANY);
	cAddr.sin_port = htons(0);

	if (0 > bind(sock, (struct sockaddr *) &cAddr, sizeof(cAddr)))
	{
		fprintf(stderr, "%s: unable to bind socket\n", argv[0]);
		exit(1);
	}

	// Not exactly the best method.
	len = 0;
	p = buf = malloc(sizeof(char) * BUFSIZE);
	buflen = BUFSIZE;

	if (!buf)
	{
		fprintf(stderr, "%s: malloc failed\n", argv[0]);
		exit(1);
	}

	do
	{
		if (len == buflen)
		{
			buf = (char *) realloc(buf, (sizeof(char) * buflen) + (sizeof(char) * BUFSIZE));
			if (!buf)
			{
				fprintf(stderr, "%s: Realloc failed\n", argv[0]);
				exit(1);
			}
			p = buf;
			p += len;
			buflen += BUFSIZE;
		}

		z = fread(p, sizeof(char), buflen - len, stdin);
		if (z > 0)
		{
			len += z;
			p += z;
		}
	}
	while (z > 0);

	/*
	fwrite(buf, len, sizeof(char), stdout);
	return 1;
	*/

	r = sendto(sock, buf, len, 0, (struct sockaddr *) &sAddr, sizeof(sAddr));
	if (0 > r)
	{
		fprintf(stderr, "r = %i\n", r);
		fprintf(stderr, "%s: unable to write to socket\n", argv[0]);
		exit(1);
	}

	return 0;
}