Added 'PROG_VER' constant, added '--version' and '--help' flags

easysock.c

@@ -44,7 +44,7 @@ void create_addr(int network, char* address, int port,struct sockaddr* dest) {
 		return;
 
 	} else {
-		exit(-2);
+		exit(2);
 	}
 		
 }
@@ -52,7 +52,7 @@ void create_addr(int network, char* address, int port,struct sockaddr* dest) {
 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);
+		exit(errno);
 	}
 	create_addr(network,address,port,addr_struct);
 	int addrlen;
@@ -61,7 +61,7 @@ int create_local (int network, char transport, char* address, int port,struct so
 	} else if (network == 6) {
 		addrlen = sizeof(struct sockaddr_in6);
 	} else {
-		exit(-7);
+		exit(7);
 	}
 
 	/* The value of addrlen should be the size of the 'sockaddr'. 
@@ -80,7 +80,7 @@ int create_remote (int network,char transport,char* address,int port,struct sock
 
 	int socket = create_socket(network,transport);
 	if (socket < 0) {
-                exit(socket);
+                exit(errno);
         }
         create_addr(network,address,port,remote_addr_struct);
         int addrlen;
@@ -89,7 +89,7 @@ int create_remote (int network,char transport,char* address,int port,struct sock
 	} else if (network == 6) {
 		addrlen = sizeof(struct sockaddr_in6);
 	} else {
-		exit(-7);
+		exit(7);
 	}
 
 	/* The value of addrlen should be the size of the 'sockaddr'. 

easysock.h

@@ -26,7 +26,7 @@ int create_socket(int network, char transport);
 port is self-explanatory;
 and dest is a pointer to the sockaddr struct that will be filled in. 
 
-The function exits with error code -2 if the network parameter contained neither '4'
+The function exits with error code 2 if the network parameter contained neither '4'
 nor '6'. */
 
 void create_addr(int network, char* address, int port,struct sockaddr* dest);
@@ -37,7 +37,7 @@ void create_addr(int network, char* address, int port,struct sockaddr* dest);
 _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 error code '-3'.*/
+It prints the error returned by 'bind' if something went wrong, and exits with error code '3'.*/
 
 int create_local (int network, char transport, char* address, int port,struct sockaddr* addr_struct);
 
@@ -46,7 +46,7 @@ int create_local (int network, char transport, char* address, int port,struct so
 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 error code '-3'.*/
+It prints the error returned by 'connect' if something went wrong, and exits with error code '3'.*/
 
 int create_remote (int network,char transport,char* address,int port,struct sockaddr* remote_addr_struct);
 

main.c

@@ -3,7 +3,8 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include "easysock.h"
-
+#define PROG_NAME "basicproxy"
+#define PROG_VER "0.01"
 void forward_data(int from_fd, int to_fd) {
 	int n = 0;
         char* buffer = malloc(3000*sizeof(char));
@@ -24,6 +25,24 @@ int check_ip_ver(char* address) {
 }
 
 
+void print_prog_info() {
+	printf("%s [Local IP address] [local port] [remote IP address] [remote port]\n",PROG_NAME);
+}
+
+void print_version_info() {
+	printf("%s %s\n",PROG_NAME,PROG_VER);
+}
+
+void print_help_info() {
+	printf("\n%s - A simple TCP proxy written in C.\n\n",PROG_NAME);
+	printf("Syntax - ");
+	print_prog_info();
+	printf("[Local IP address] - The local address to bind to\n"
+		"[local port] - The local port to listen on\n"
+		"[remote IP address] - The remote IP to connect to\n"
+		"[remote port] - The remote port to connect to\n");
+	printf("\nExample: %s 127.0.0.1 3000 1.2.3.4 5000 - Listen on '127.0.0.1:3000', and forward all data from there to '1.2.3.4:5000'\n\n",PROG_NAME);
+}
 int main(int argc,char* argv[]) {
 
 /* argv[1] = local address
@@ -31,6 +50,22 @@ int main(int argc,char* argv[]) {
    argv[3] = remote address
    argv[4] = remote port */
 
+	if (argc == 2) {
+		if (strcmp(argv[1],"-v") == 0 || strcmp(argv[1],"--version") == 0) {
+			print_version_info();
+			exit(0);
+		} else if (strcmp(argv[1],"-h") == 0 || strcmp(argv[1],"--help") == 0) {
+			print_help_info();
+			exit(0);
+		}
+	}
+
+	if (argc != 5) {
+		print_prog_info();
+		exit(30);
+	}
+
+
 	char* local_addr = argv[1];
 	int local_port = strtol(argv[2],NULL,10);
 	char* remote_addr = argv[3];
@@ -41,7 +76,7 @@ int main(int argc,char* argv[]) {
 	printf("Using %d for local\nUsing %d for remote\n",preferred_local_network,preferred_remote_network);
 
 	if ((preferred_local_network == -1) || (preferred_remote_network == -1)) {
-		exit(-7);
+		exit(7);
 	}
 
 	char preferred_transport = 'T';
@@ -53,7 +88,7 @@ int main(int argc,char* argv[]) {
 	} else if (check_ip_ver(local_addr) == 6) {
 		addrlen = sizeof(struct sockaddr_in6);
 	} else {
-		exit(-7);
+		exit(7);
 	}
 
 	listen(server_sock,50);  /* Arbitrary number, change later */