basic-proxy/easysock.c

#include "easysock.h"

int create_socket(int network, char transport) {  
	int domain;
	int type;

	if (network == 4) {
		domain = AF_INET;
	} else if (network == 6) {
		domain = AF_INET6;
	} else {
		return -1;
	}

	if (transport == 'T') {
		type = SOCK_STREAM;
	} else if (transport == 'U') {
		type = SOCK_DGRAM;
	} else {
		return -1;
	}

	int newSock = socket(domain,type,0);
	return newSock;
}


void create_addr(int network, char* address, int port,struct sockaddr* dest) {
	if (network == 4) {
		struct sockaddr_in listen_address;
		
		listen_address.sin_family = AF_INET;
		listen_address.sin_port = htons(port);
		inet_pton(AF_INET,address,&listen_address.sin_addr);
		memcpy(dest,&listen_address,sizeof(listen_address));
		return;	

	} else if (network == 6) {
		struct sockaddr_in6 listen_ipv6;
		listen_ipv6.sin6_family = AF_INET6;
		listen_ipv6.sin6_port = htons(port);
		inet_pton(AF_INET6,address,&listen_ipv6.sin6_addr);
		memcpy(dest,&listen_ipv6,sizeof(listen_ipv6));
		return;

	} else {
		exit(-2);
	}
		
}

int create_local (int network, char transport, char* address, int port,struct sockaddr* addr_struct) {
	int socket = create_socket(network,transport);
	if (socket < 0) {
		exit(socket);
	}
	create_addr(network,address,port,addr_struct);
	int addrlen;
	if (network == 4) {
		addrlen = sizeof(struct sockaddr_in);
	} else if (network == 6) {
		addrlen = sizeof(struct sockaddr_in6);
	} else {
		exit(-7);
	}

	/* The value of addrlen should be the size of the 'sockaddr'. 
	This should be set to the size of 'sockaddr_in' for IPv4, and 'sockaddr_in6' for IPv6.
	See https://stackoverflow.com/questions/73707162/socket-bind-failed-with-invalid-argument-error-for-program-running-on-macos */

	int i = bind (socket,addr_struct,(socklen_t)addrlen);
	if (i < 0) {
		exit(errno);
	}
	return socket;
}

int create_remote (int network,char transport,char* address,int port) {


	int socket = create_socket(network,transport);
	if (socket == -1) {
                exit(-1);
        }
	struct sockaddr remote_addr_struct;
        create_addr(network,address,port,&remote_addr_struct);
        int addrlen;
	if (network == 4) {
		addrlen = sizeof(struct sockaddr_in);
	} else if (network == 6) {
		addrlen = sizeof(struct sockaddr_in6);
	} else {
		exit(-7);
	}

	/* The value of addrlen should be the size of the 'sockaddr'. 
	This should be set to the size of 'sockaddr_in' for IPv4, and 'sockaddr_in6' for IPv6.
	See https://stackoverflow.com/questions/73707162/socket-bind-failed-with-invalid-argument-error-for-program-running-on-macos */

        int i = connect(socket,&remote_addr_struct,(socklen_t)addrlen);
	if (i < 0) {
		exit(errno);
	}
        return socket;
}