threephaseforwarder.c

/* threephaseforwarder.c */
#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <string.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <arpa/inet.h> 
#include <netinet/in.h> 

#define LOCAL_IP "127.0.0.1"
#define REMOTE_IP "192.168.42.8"
#define GEN_PORT 5367
#define PY_PORT 6367
#define MAXLINE 1024 

int main() { 
	int sockpifd, sockpcfd, n, clilen, servlen, genlen, pylen;
	float phasevals[4], pythonargs[4];
	char clientaddress[40], serveraddress[40];
	struct sockaddr_in servaddr, cliaddr, genaddr, pyaddr;
	
	// Creating socket file descriptors 
	if ((sockpifd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ||
	 	(sockpcfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0){ 
		perror("socket creation failed"); 
		exit(EXIT_FAILURE); 
	} 

	// Set the datagram memory value to 0
	memset(&servaddr, 0, sizeof(servaddr)); 
	memset(&cliaddr, 0, sizeof(cliaddr)); 
	memset(&genaddr, 0, sizeof(genaddr)); 
	
	// Listening UDP server information 
	servaddr.sin_family = AF_INET; // IPv4 
	servaddr.sin_port = htons(PY_PORT); 
	servaddr.sin_addr.s_addr = INADDR_ANY;

	// 3 Phase Generator setup
	genaddr.sin_family = AF_INET;
	genaddr.sin_port = htons(GEN_PORT);
	inet_aton(LOCAL_IP, &genaddr.sin_addr);
	
	// Python client setup
	pyaddr.sin_family = AF_INET;
	pyaddr.sin_port = htons(PY_PORT);
	inet_aton(REMOTE_IP, &pyaddr.sin_addr);
	
	// Bind the socket with the server address 
	if ( bind(sockpcfd, (const struct sockaddr *)&servaddr, 
			sizeof(servaddr)) < 0 ) 
	{ 
		perror("bind failed"); 
		exit(EXIT_FAILURE); 
	} 

	// Get size of datagrams
	clilen = sizeof(cliaddr);
	servlen = sizeof(servaddr);
	genlen = sizeof(genaddr);
	pylen = sizeof(pyaddr);

	// Listen for start signal from python client
	n = recvfrom(sockpcfd, (float *)pythonargs, sizeof(pythonargs), 
				0, ( struct sockaddr *) &cliaddr, 
				&clilen); 

	inet_ntop(AF_INET, &cliaddr.sin_addr, clientaddress, sizeof(clientaddress));

	if (pythonargs[3] > 0) {
		// Print debug python client information
		printf("Length = %d\n", n);
		printf("Receive noise = %8.3f\n", pythonargs[0]);
		printf("Receive time step = %8.3f\n", pythonargs[1]);
		printf("Receive frequency = %8.3f\n", pythonargs[2]);
		printf("Receive debug = %8.3f\n", pythonargs[3]);
		printf("Python address = %s\n", clientaddress);
		printf("Python port = %d\n", htons(cliaddr.sin_port));
	}

	// Send start signal to generator server
	sendto(sockpifd, (const float *)pythonargs, sizeof(pythonargs), 
			0, (const struct sockaddr *) &genaddr, 
				genlen); 

	inet_ntop(AF_INET, &genaddr.sin_addr, serveraddress, sizeof(serveraddress));

	if (pythonargs[3] > 0) {
		// Print debug generator server information
		printf("Send noise = %8.3f\n", pythonargs[0]);
		printf("Send time step = %8.3f\n", pythonargs[1]);
		printf("Send frequency = %8.3f\n", pythonargs[2]);
		printf("Send debug = %8.3f\n", pythonargs[3]);
		printf("Generator address = %s\n", serveraddress);
		printf("Generator port = %d\n", htons(genaddr.sin_port));
	}

	while(1) {
		// Receive simulated 3 phase power data from generator server
		n = recvfrom(sockpifd, (float *)phasevals, sizeof(phasevals), 
				0, ( struct sockaddr *) &genaddr, 
				&genlen); 
		
		// Relay simulated 3 phase power data to python client
		sendto(sockpcfd, (const float *)phasevals, sizeof(phasevals), 
			0, (const struct sockaddr *) &pyaddr, 
				pylen); 

		if (pythonargs[3] > 0) {
			// Debug print
			printf("Phase values : %8.3f | %8.3f | %8.3f | Time (s): %8.2f\n", phasevals[0], phasevals[1], phasevals[2], phasevals[3]);
		}
		
		// Pause the receiving/sending for specified seconds
		usleep((pythonargs[2] - 5)*1000);
	}
	
	return 0; 
}