Add basic client socket config

http/README.md

@@ -0,0 +1,20 @@
+# http
+The aim of these two modules is to implement a client and a server that partially implement HTTP 1.1
+
+## client
+
+The client takes a URL as input, connects to the corresponding server on the corresponding port(`80` by default) and requests the file specified in
+the URL. The transmitted content of that file is written to `stdout`, to a file or to a directory.
+
+    SYNOPSIS
+    client [-p PORT] [ -o FILE | -d DIR ] URL
+
+    EXAMPLE
+    client http://ivayloivanov.eu/en/
+
+
+## server
+
+Not implemented yet
+
+**Note: The description is from the task I got from TU.**

http/client.c

@@ -1,14 +1,38 @@
+/**
+ * @file client.c
+ * @author Ivaylo Ivanov 11777707
+ * @date 03.11.2018
+ *
+ * @brief Client program module.
+ *
+ * The client module takes a URL as input, connects to the corresponding server on the corresponding
+ * port(`80` by default) and requests the file specified in the URL.
+ * The content of that file is written to `stdout`, to a file or to a directory.
+ *
+ *   SYNOPSIS
+ *   client [-p PORT] [ -o FILE | -d DIR ] URL
+ *
+ *   EXAMPLE
+ *   client http://ivayloivanov.eu/en/
+ *
+ **/
+
 #define _GNU_SOURCE ///< in order for optarg to be defined
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
 #include "shared/http.h"
 
+static struct addrinfo* get_host_info(const char *hostname, char *port);
+
 int main(int argc, char *argv[]) {
     check_opts_number(argc);
 
-    int port = 80;
+    char *port = "80";
     char *ofile = NULL;
     char *dir = NULL;
     char *url = NULL;
@@ -18,7 +42,7 @@ int main(int argc, char *argv[]) {
     while((c = getopt(argc, argv, "p:o:d:h")) != -1) {
         switch(c) {
             case 'p':
-                port = atoi(optarg);
+                port = optarg;
                 break;
             case 'o':
                 ofile = optarg;
@@ -57,6 +81,11 @@ int main(int argc, char *argv[]) {
 
     const char *full_url = strstr(url, "http://") + 7; //< the full url starts after http://
     const char *path = strstr(full_url, "/");
+    const char *hostname = "google.com"; //< TODO: Change this later
+
+    struct addrinfo* res = get_host_info(hostname, port); //< Check if the address is resolvable
+
+    freeaddrinfo(res); //< Free the addrinfo struct
 }
 
 static void print_usage(void) {
@@ -67,7 +96,7 @@ static void print_usage(void) {
  * @brief Function to check the number of arguments
  * @details Checks the number of arguments supplied to the command line.
  *          If the arguments are less than the required or more than possible, it exits
- * @param argc Number of arguments obtained from the command line
+ * @param argc - Number of arguments obtained from the command line
  * @return none
  *
  **/
@@ -82,3 +111,38 @@ static void check_opts_number(int argc) {
         exit(EXIT_FAILURE);
     }
 }
+
+/**
+ * @brief Function to check if the address is resolvable by the client
+ * @details Checks if the address is resolvable by the client.
+ *          If the address is resolvable, it writes the result to res
+ *          If the address is not resolvable, it exits with an error
+ * @param
+ *          hostname - The address to be resolved
+ *          port     - The port to try
+ * @return res - The result of getaddrinfo()
+ *
+ **/
+static struct addrinfo* get_host_info(const char *hostname, char *port) {
+    struct addrinfo hints; //< Configuration for the client
+    hints.ai_family = AF_INET; //< Use IPv4
+    hints.ai_socktype = SOCK_STREAM; //< Stream socket
+    hints.ai_flags = 0; //< Do not use any flags
+    hints.ai_protocol = IPPROTO_TCP; //< Use only TCP
+
+    struct addrinfo* res = NULL;
+
+    int err = getaddrinfo(hostname, port, &hints, &res);
+
+    if(err != 0) {
+        (void) fprintf(stderr, "ERROR:  %s\n", gai_strerror(err));
+        exit(EXIT_FAILURE); //< Exit if there is an error
+    }
+
+    if(res == NULL) {
+        (void) fprintf(stderr, "ERROR:  Could not resolve address %s\n", hostname);
+        exit(EXIT_FAILURE); //< Exit if the address is not resolved
+    }
+
+    return res;
+}

http/shared/http.h

@@ -1,7 +1,7 @@
 #ifndef HTTP_HEADER_FILE
 #define HTTP_HEADER_FILE
 
-static void print_usage();
+static void print_usage(void);
 static void check_opts_number(int argc);
 
 #endif