test.c

开源的组播程序

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>


#include <rs.h>

#define NN 255
#define SYMSIZE 8
#define GENPOLY 0x187
#define FCS 1
#define PRIM 1
#define NROOTS 8

#define PAYLOAD 1000

unsigned int send_packet (unsigned char * packet, unsigned int index,
		unsigned char * destination);

struct pmtp_header {
	unsigned char tigertree[160];
	unsigned int filesize;
	unsigned int segmentsize;
	unsigned int sequence;
	unsigned int symsize;
	unsigned int genpoly;
	unsigned int fcs;
	unsigned int prim;
	unsigned int nroots;
};
	
int main () {
	unsigned char *source, *destination, *copy;
	unsigned char *packets, sourcepacket[PAYLOAD];
	unsigned char block[NN];
	unsigned int blocksize = (NN - NROOTS) * PAYLOAD;
	int i, index;
	int errlocs[NROOTS];
	int erasures = 0;
	int derrors;
	void *handle;
	int bytes_read;
	unsigned char const filename[] = "/home/steven/pmtp/weezer-hashpipe.mp3";
	int fdin, fdout;
	struct hostent *hp;
	struct servent *sp;
	struct sockaddr_in sin;
	int s;

	if ((s = socket (AF_INET, SOCK_DGRAM, 0)) < 0) {
		perror ("socket");
		exit (1);
	}

	if ((sp = getservbyname ("pmtp", "udp")) == NULL) {
		fprintf (stderr, "%s/udp: unknown service\n", "pmtp");
		exit (1);
	}
	if ((hp = gethostbyname ("PII")) == NULL) {
		fprintf (stderr, "%s: host unknown.\n", "PII");
		exit (1);
	}
	sin.sin_family = AF_INET;
	sin.sin_port = sp->s_port;
	bcopy (hp->h_addr, &sin.sin_addr, hp->h_length);

	srandom(time(NULL));
	printf ("Code (%d / %d)\n", NN, NROOTS);
	if((handle = init_rs_char(SYMSIZE,GENPOLY,FCS,PRIM,NROOTS)) == NULL) {
		printf("init_rs_int failed!\n");
		exit (1);
	}
	if ((source = (unsigned char*) malloc (PAYLOAD * (NN-NROOTS))) == NULL) {
		printf ("Couldn't malloc %d bytes for source\n",
			PAYLOAD * (NN - NROOTS));
		exit (1);
	}
	if ((packets = (unsigned char*) malloc (PAYLOAD * NN)) == NULL) {
		printf ("Couldn't malloc %d bytes for packets\n", PAYLOAD * NN);
		exit (1);
	}
	if ((destination = (unsigned char*) calloc (PAYLOAD * NN, 1)) == NULL) {
		printf ("Couldn't malloc %d bytes for destination\n", PAYLOAD * NN);
		exit (1);
	}
	if ((copy = (unsigned char*) malloc (blocksize)) == NULL) {
		printf ("Couldn't malloc %d bytes for destination\n", blocksize);
		exit (1);
	}
	if ((fdin = open(filename, O_RDONLY)) < 0) {
		printf ("Error opening %s for reading\n", filename);
		exit (1);
	}
	if ((fdout = open ("/home/steven/test.out", O_WRONLY | O_CREAT,
			00755 )) < 0) {
		printf ("Error opening '/home/steven/test.out' for writing\n");
		exit (1);
	}
	while ((bytes_read = read(fdin, source, blocksize)) != 0) {
		erasures = 0;
		for (index = 0; index < PAYLOAD; index++) {
			memcpy (block, (source + index * (NN-NROOTS)), NN-NROOTS);
			encode_rs_char (handle, block, &block[NN-NROOTS]);

			for (i = 0; i < NN; i++) {
				*(packets + PAYLOAD * i + index) = block[i];
			}
		}
		for (i = 0; i < NN; i++) {
			memcpy (sourcepacket, packets + i * PAYLOAD, PAYLOAD);
			if (send_packet (sourcepacket, i, destination)) {
				if (erasures < NROOTS) {
					errlocs[erasures] = i;
				}
				erasures++;
			} else {
				if (sendto (s, copy, PAYLOAD, 0,
						(struct sockaddr *) &sin, sizeof(sin)) < 0) {
					perror ("sendto");
					exit (1);
				}
			}
		}
/*
		if (erasures > NROOTS) {
			printf ("Exiting because there were %d packets lost\n", erasures);
			exit (1);
		}
*/
		for (i = 0; i < PAYLOAD; i++) {
			for (index = 0; index < NN; index++) {
				block[index] = *(destination + index * PAYLOAD + i);
			}
			if ((derrors = decode_rs_char (handle, block, errlocs, erasures))
					== -1) {
				printf ("Decode failed!\n");
				exit (1);
			}
			memcpy (copy + i * (NN - NROOTS), block, NN - NROOTS);
		}
		write (fdout, copy, bytes_read);
		if (memcmp (copy, source, PAYLOAD * (NN - NROOTS))) {
			printf ("Decode failed with %d lost packets\n",erasures);
		} else {
			printf ("Seemed to have worked with %d lost packets\n", erasures);
		}
	}
	free (copy);
	close (fdout);
	close (fdin);
	free (source);
	free (packets);
	free (destination);
	return 0;
}

unsigned int send_packet (unsigned char * packet, unsigned int index,
		unsigned char * destination) {
	if ((random() & 255) < 10) {
		printf ("Aiyeeee, lost packet %d!\n", index);
		return 1;

	}
	memcpy (destination + index * PAYLOAD, packet, PAYLOAD);
	return 0;
}