Added socket library files

easysock.c

@@ -0,0 +1,169 @@
+#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(202);
+	}
+		
+}
+
+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(errno);
+	}
+	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(207);
+	}
+
+	/* 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,struct sockaddr* remote_addr_struct) {
+
+	struct addrinfo hints;  /* Used to tell getaddrinfo what kind of address we want */
+	struct addrinfo* results; /* Used by getaddrinfo to store the addresses */
+
+
+	if (check_ip_ver(address) < 0) { /* If the address is a domain name */
+		int err_code;
+		char* port_str = malloc(10 * sizeof(char));
+
+		sprintf(port_str,"%d",port); /* getaddrinfo expects a string for its port */
+
+
+		memset(&hints,'\0',sizeof(hints));
+		hints.ai_socktype = char_to_socktype(transport);
+
+		err_code = getaddrinfo(address,port_str,&hints,&results);
+		if (err_code != 0) {
+			exit(err_code);
+		}
+		remote_addr_struct = results->ai_addr;
+		network = inet_to_int(results->ai_family);
+	} else {
+	        create_addr(network,address,port,remote_addr_struct);
+	}
+
+	int socket = create_socket(network,transport);
+	if (socket < 0) {
+                exit(errno);
+        }
+
+       	int addrlen;
+	if (network == 4) {
+		addrlen = sizeof(struct sockaddr_in);
+	} else if (network == 6) {
+		addrlen = sizeof(struct sockaddr_in6);
+	} else {
+		exit(207);
+	}
+
+	/* 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;
+}
+
+
+int check_ip_ver(char* address) {
+	char buffer[16]; /* 16 chars - 128 bits - is enough to hold an ipv6 address */
+	if (inet_pton(AF_INET,address,buffer) == 1) {
+		return 4;
+	} else if (inet_pton(AF_INET6,address,buffer) == 1) {
+		return 6;
+	} else {
+		return -1;
+	}
+}
+
+int int_to_inet(int network) {
+	if (network == 4) {
+		return AF_INET;
+	} else if (network == 6) {
+		return AF_INET6;
+	} else {
+		exit(207);
+	}
+}
+
+int inet_to_int(int af_type) {
+	if (af_type == AF_INET) {
+		return 4;
+	} else if (af_type == AF_INET6) {
+		return 6;
+	} else {
+		exit(207);
+	}
+}
+
+int char_to_socktype(char transport) {
+	if (transport == 'T') {
+		return SOCK_STREAM;
+	} else if (transport == 'U') {
+		return SOCK_DGRAM;
+	} else {
+		exit(250);
+	}
+}

easysock.h

@@ -0,0 +1,75 @@
+#ifndef EASYSOCK_H_
+#define EASYSOCK_H_
+
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <arpa/inet.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+
+
+/* This function takes:
+a layer 3 - network layer - integer, which must be '4' for IPv4
+and 6 for IPv6; and
+a layer 4 - transport layer - character, which must be 'T' for
+TCP or 'U' for UDP. 
+
+It returns the created socket, or -1 if the socket creation failed.*/
+
+int create_socket(int network, char transport);
+
+
+/* This function fills in the sockaddr struct 'dest' based on the given information.
+'network' is an integer that contains '4' for IPv4 or '6' for IPv6;
+'address' is the address that is filled into the struct;
+port is self-explanatory;
+and dest is a pointer to the sockaddr struct that will be filled in. 
+
+The function exits with error code 202 if the network parameter contained neither '4'
+nor '6'. */
+
+void create_addr(int network, char* address, int port,struct sockaddr* dest);
+
+
+
+/* This function utilizes the above two functions; it creates the socket and
+_binds_ the addresses. It is used for local sockets (server sockets). Parameters are
+same as above. 
+
+It prints the error returned by 'bind' if something went wrong, and exits with errno.*/
+
+int create_local (int network, char transport, char* address, int port,struct sockaddr* addr_struct);
+
+
+/* This function utilizes the same functions as 'create_local' but _connects_ to the
+requested address. It is used for remote sockets (client sockets). The paramters are same
+as above. This function needs an empty 'sockaddr *' structure passed to it, which it will fill.
+
+It prints the error returned by 'connect' if something went wrong, and exits with errno.*/
+
+int create_remote (int network,char transport,char* address,int port,struct sockaddr* remote_addr_struct);
+
+/* check_ip_ver - This function checks if the given string is an IPv4 address (returns 4), 
+IPv6 address (returns 6) or neither (returns -1). */
+
+int check_ip_ver(char* address);
+
+/* int_to_inet - Takes an int value (4 for IPv4, 6 for IPv6) and returns AF_INET or
+AF_INET6 respectively. */
+
+int int_to_inet(int network);
+
+/* char_to_socktype - Takes a character that represents a transport-layer protocol
+(currently only supports 'T' for TCP or 'U' for UDP - exits with error code 250 if 
+the given characters is neither of these) and return the appropriate SOCKTYPE value. */
+
+int char_to_socktype(char transport);
+
+/* inet_to_int - Takes an int value that corresponds to AF_INET or AF_INET6,
+and returns the appropriate int value. */
+int inet_to_int(int af_type);
+
+#endif