// Simple sink program that opens a tcp socket on a random port
// and then reads everything the socket has to write and then ends.

#define _GNU_SOURCE

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

#include <errno.h>
#include <time.h>
#include <unistd.h>

#include <sys/socket.h>
#include <netinet/in.h>

enum {
	USAGE_ERROR = 1,
	SOCKET_ERROR,
	BIND_INUSE,
	BIND_ERROR,
	GETNAME_ERROR,
	LISTEN_ERROR,
	ACCEPT_ERROR,
	READ_ERROR
};

enum { buffer_len = 10240 };
char buffer[buffer_len];

enum { TIMEGRAN = 1000000000LL };

int main(int argc, char * argv[]) {
	int port = 0;
	switch(argc) {
	case 1: break;
	case 2:
		{
			const char * const str = argv[1];
			char* endptr;
			unsigned long long ret = strtoul(str, &endptr, 10);
			if('\0' != *endptr) { fprintf( stderr, "Invalid argument \"%s\" (not a number)\n", str ); goto USAGE;}
			if(errno == ERANGE || ret > 65535)  { fprintf( stderr, "Invalid argument \"%s\" (value too large)\n", str ); goto USAGE;}

			port = ret;
			break;
		}
	USAGE:
	default:
		fprintf( stderr, "USAGE: %s [port]\n", argv[0] );
		exit( USAGE_ERROR );
	}

	printf( "%d: Listening on port %d\n", getpid(), port );
	int listenfd = socket(AF_INET, SOCK_STREAM, 0);
	if(listenfd < 0) {
		fprintf( stderr, "socket error: (%d) %s\n", (int)errno, strerror(errno) );
		exit( SOCKET_ERROR );
	}

	int ret = 0;
	struct sockaddr_in address;
	socklen_t addrlen = sizeof(address);
	memset( (char *)&address, '\0', addrlen );
	address.sin_family = AF_INET;
	address.sin_addr.s_addr = htonl( INADDR_ANY );
	address.sin_port = htons( port );

	ret = bind( listenfd, (struct sockaddr *) &address, addrlen );
	if(ret < 0) {
		if(errno == EADDRINUSE) {
			fprintf( stderr, "Port already in use in non-interactive mode. Aborting\n" );
			exit( BIND_INUSE );
		}
		fprintf( stderr, "bind error: (%d) %s\n", (int)errno, strerror(errno) );
		exit( BIND_ERROR );
	}

	ret = getsockname( listenfd, (struct sockaddr *) &address, &addrlen );
	if(ret < 0) {
		fprintf( stderr, "getname error: (%d) %s\n", (int)errno, strerror(errno) );
		exit(GETNAME_ERROR);
	}

	printf( "actial port: %d\n", ntohs(address.sin_port) );

	ret = listen( listenfd, 1 );
	if(ret < 0) {
		fprintf( stderr, "listen error: (%d) %s\n", (int)errno, strerror(errno) );
		exit( 5 );
	}

	for(int i = 0; i < 2; i++) {
		struct sockaddr_in cli_addr;
		__socklen_t clilen = sizeof(cli_addr);
		int fd = accept( listenfd, (struct sockaddr *) &cli_addr, &clilen );
		if(fd < 0) {
			fprintf( stderr, "accept error: (%d) %s\n", (int)errno, strerror(errno) );
			exit( ACCEPT_ERROR );
		}

		int error = 0;
		size_t calls = 0;
		size_t bytes = 0;

		struct timespec after, before;

		clock_gettime(CLOCK_MONOTONIC, &before);

		for(;;) {
			ret = recv(fd, buffer, buffer_len, 0);
			if(ret == 0 ) goto EXIT;
			if(ret < 0 ) {
				if( errno == EAGAIN || errno == EWOULDBLOCK) continue;
				if( errno == ECONNRESET ) { printf("Connection reset\n"); goto EXIT; }
				if( errno == EPIPE ) { printf("Pipe closed\n"); goto EXIT; }
				fprintf( stderr, "accept error: (%d) %s\n", (int)errno, strerror(errno) );
				error = READ_ERROR;
				goto EXIT;
			}
			calls++;
			bytes += ret;
		}
		EXIT:;

		clock_gettime(CLOCK_MONOTONIC, &after);

		uint64_t tb = ((int64_t)before.tv_sec * TIMEGRAN) + before.tv_nsec;
		uint64_t ta = ((int64_t)after.tv_sec * TIMEGRAN) + after.tv_nsec;
		double secs = ((double)ta - tb) / TIMEGRAN;

		printf("Received %'zu bytes in %'zu reads, %f seconds\n", bytes, calls, secs);
		printf(" - %'3.3f bytes per second\n", (((double)bytes) / secs));
		printf(" - %'3.3f bytes per calls\n", (((double)bytes) / calls));

		close(fd);
		if(error != 0) exit( error );
	}
	close(listenfd);
	return 0;
}