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