http_client.c

#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 
#include <unistd.h>
#include <sys/types.h>

char *get(char *, int);
void open_file(char *dest);

int main() {
	 char *url = NULL;
	 int len;
	 getline(&url, &len, stdin);

	 char *tmp = strchr(url, '\n');
	 if(tmp != NULL)
	 	*tmp = '\0';

	 char *dest = get(url, len);

	 if(dest != NULL) {
		 open_file(dest);
	 }

	 free(dest);
 }

char *fetch(char *host, int port, char* loc);

char *get(char * url, int len) {
	int port = 80;
	char *host, *location;

	char *proto_excluded = strstr(url, "//");

	if(proto_excluded != NULL)
		proto_excluded += 2;
	else
		proto_excluded = url;

	location = strchr(proto_excluded, '/');

	int host_length;
	if(location == NULL)
		host_length = strlen(proto_excluded);
	else
		host_length  = location - proto_excluded;

	host = malloc(sizeof(char) * (host_length + 1));

	strncpy(host, proto_excluded, host_length);
	host[host_length] = '\0';

	char *ptr = strchr(host, ':');

	if(ptr != NULL) {
		port = atoi(ptr + 1);
		*ptr = '\0';
		host_length -= strlen(ptr + 1);
	}

	char *dest;

	if(location == NULL) {
		dest = fetch(host, port, "/");
	}
	else {
		dest = fetch(host, port, location);
	}

	free(host);

	return dest;
}

void open_file(char *dest) {
	pid_t child = fork();

	if(child < 0)  {
		perror("Error forking");
	}
	else if(child == 0) {
		 int devNull = open("/dev/null", O_WRONLY);
		 dup2(devNull, STDOUT_FILENO);
		 dup2(devNull, STDERR_FILENO);
		 close(devNull);
		 execl("/usr/bin/xdg-open", "xdg-open", dest, (char *)0);
		 exit(0);
	}
	else {
		wait();
	}
}

char *fetch(char *host, int port, char* loc){
	printf("host: %s, port : %d, loc: %s\n", host, port, loc);

	char tmpname[] = "/tmp/text_file";
	char *fileName = malloc(sizeof(char) * sizeof(tmpname));
	strcpy(fileName, tmpname);

	int sockfd = 0;
	const int buffSize = 1024;
	char recvBuff[buffSize], sendBuff[buffSize];
	struct sockaddr_in serveraddr; 
	struct hostent *server;

	sockfd = socket(AF_INET, SOCK_STREAM, 0);

	if(sockfd < 0) {
		perror("Failed to create socket\n");
		return NULL;
	}

	server = gethostbyname(host);
	if (server == NULL) {
		fprintf(stderr,"ERROR, no such host as %s\n", host);
		return NULL;
	}

	bzero((char *) &serveraddr, sizeof(serveraddr));
	serveraddr.sin_family = AF_INET;
	bcopy((char *)server->h_addr, 
			(char *)&serveraddr.sin_addr.s_addr, server->h_length);
	serveraddr.sin_port = htons(port);

	if (connect(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < 0) {
		perror("Failed to connect to server\n");
		return NULL;
	}

	sprintf(sendBuff, "GET %s HTTP/1.0\r\nHost: %s\r\n\r\n", loc, host);

	int n = write(sockfd, sendBuff, strlen(sendBuff));

	if(n <= 0) {
		perror("Failed to write to socket\n");
		return NULL;
	}

	FILE *fp = fopen(fileName, "w+");

	bool header_ended = false;
	char *ptr;
	while((n = read(sockfd, recvBuff, buffSize)) > 0) {

		if(header_ended == false && (ptr = strstr(recvBuff, "\r\n\r\n")) != NULL) {
			ptr = ptr + 4;
			fwrite(ptr, sizeof(char), n - (ptr - recvBuff) + 1, fp);
			header_ended = true;
		}
		else if(header_ended == true) {
			fwrite(recvBuff, sizeof(char), n, fp);
		}
	}

	fclose(fp);

	return fileName;
}