// This tiny program connects repeatedly to a server and sends patterns of garbage to it
// Example:
//   garbage_tcp 127.0.0.1 22 10 1 10 1
// It stops when all patterns have been tried, or when connection is refused (server has shut down)
 
#include <stdio.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>

#include <assert.h>

static const char *server_addr="127.0.0.1";
static in_port_t server_port=7;

static void send_it(const char *buf, size_t buflen)
{
	int fd = socket(AF_INET,SOCK_STREAM,0);
	assert(fd>=0);
	struct sockaddr_in sa;
	memset(&sa,0,sizeof(sa));
	sa.sin_family=AF_INET;
	sa.sin_addr.s_addr = inet_addr(server_addr);
	sa.sin_port = ntohs(server_port);
	
	if(connect(fd,(sockaddr*)(void*)&sa,(socklen_t)(sizeof(sa)))!=0) {
		printf("connect() failed, server is probably dead\n");
		exit(EXIT_SUCCESS);
	}
	
	if(buflen!=0) {
		long tot_bytes=0;
		for(;;) {
			long bytes_written=write(fd,buf,buflen);
			if(bytes_written<=0) {
				printf("Connection closed after %ld bytes",tot_bytes);
				break;
			}
			tot_bytes+=bytes_written;
		}
	}
	close(fd);
}


static const uint8_t filldata[] = { 0, 1, 2, 0xfe, 0xff };

static void chunk_loop(size_t buflen, char *buf, size_t clen, uint8_t *c) {
	unsigned *c_idx=new unsigned[clen];
	memset(c_idx,0,sizeof(unsigned)*clen);
	for(;;) {
		int i=clen-1;
		for(;;) {
			c_idx[i]++;
			if(c_idx[i]<sizeof(filldata))
				break;
			c_idx[i]=0;
			i--;
			if(i<0) return;
		}
		
		printf(" ");
		for(size_t j=0; j<clen; j++)
			printf(" %u",c_idx[j]);
		printf(":"); fflush(stdout);

		//fill buf
		for(size_t j=0; j<clen; j++)
			c[j] = filldata[c_idx[j]];
		for(size_t j=0; j<buflen; j+= clen) {
			if(j+clen<buflen)
				memcpy(buf+j,c,clen);
			else
				memcpy(buf+j,c,buflen-j);
		}
		
		send_it(buf,buflen);
		printf("\n"); fflush(stdout);
	}
}

static void run(size_t max_length, size_t length_inc, size_t max_chunk_length, size_t chunk_inc) {
	for(size_t length=1; length<max_length; length+=length_inc) {
		char *buf=new char[length];
		for(size_t chunk_size=1; chunk_size<length && chunk_size<max_chunk_length; chunk_size+=chunk_inc) {
			uint8_t *c=new uint8_t[chunk_size];
			printf("length=%u chunk_size=%u\n",(unsigned)length,(unsigned)chunk_size); fflush(stdout);
			chunk_loop(length,buf,chunk_size,c);
			delete[] c;
		}
		delete[] buf;
	}
}

int main(int argc, char **argv) {
	if(argc!=7) {
		fprintf(stderr,"usage: garbage_tcp <server-ip> <server-port> <max-length> <length-inc> <max-chunk-size> <chunk-inc>\n");
		return EXIT_FAILURE;
	}
	server_addr = argv[1];
	server_port=strtoul(argv[2],0,0);
	run(strtoul(argv[3],0,0), strtoul(argv[4],0,0), strtoul(argv[5],0,0), strtoul(argv[6],0,0));
	return 0;
}