http downlaoder

#if defined(_WIN32)
#include "WinSock2.h"
#include "Ws2tcpip.h"
#pragma comment(lib, "ws2_32.lib")
#elif defined(linux)
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#else
#error gtfo macfag.
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>

void
help()
{
    puts("dl - by Jakash3\n"
         "Downloads specified file from web server.\n"
         "Usage: dl URL OUTFILE\n");
    exit(1);
}

void
fail(const char *format, ...)
{
    va_list v;
    va_start(v, format);
    vprintf(format, v);
    exit(1);
}

void
cr()
{
#if defined(linux)
    putchar('\r');
    fflush(stdout);
#elif defined(_WIN32)
    HANDLE out = GetStdHandle(STD_OUTPUT_HANDLE);
    struct _CONSOLE_SCREEN_BUFFER_INFO bi;
    GetConsoleScreenBufferInfo(out, &bi);
    bi.dwCursorPosition.X = 0;
    SetConsoleCursorPosition(out, bi.dwCursorPosition);
#endif
}

int
main(int argc, char **argv)
{
    if (argc < 2)
        help();

#if defined(_WIN32)
    struct WSAData *wd = (struct WSAData *)malloc(sizeof(struct WSAData));
    if (WSAStartup(MAKEWORD(2, 0), wd))
        fail("Failed to initialize Winsock API.\n");
    free(wd);
    SOCKET sock;
#elif defined(linux)
    int sock;
#endif

    char c;
    int i, j, k, l, m;
    FILE *f;
    char *file;
    char *host = argv[1];
    struct addrinfo *ai;
    struct addrinfo hints;
    char buf[512];

    if (argc == 3)
        file = argv[2];
    else
        file = strrchr(argv[1], '/') + 1;
    if (!(f = fopen(file, "w")))
        fail("Error. Failed to open: %s", argv[2]);
    if (strstr(argv[1], "http://") == argv[1])
        host += 7;
    memset(&hints, 0, sizeof(struct addrinfo));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = IPPROTO_TCP;
    sprintf(buf, "GET %s HTTP/1.1\r\n", argv[1]);
    *strchr(host, '/') = ' ';
    if (i = getaddrinfo(host, "80", &hints, &ai))
        fail("Error. %s\n", gai_strerror(i));
    sprintf(buf + strlen(buf), "Host: %s\r\n\r\n", host);
    sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
    if (connect(sock, ai->ai_addr, ai->ai_addrlen))
        fail("Error. Failed to connect to host.\n");
    freeaddrinfo(ai);
    i = send(sock, buf, strlen(buf), 0);
    if (i < strlen(buf) || i == -1)
        fail("Error. Failed to send GET request!\n");
    while (strcmp(buf, "\r\n")) {
        for (i = 0; strcmp(buf + i - 2, "\r\n"); i++) {
            recv(sock, buf + i, 1, 0);
            buf[i + 1] = ' ';
        }
        if (strstr(buf, "HTTP/") == buf) {
            fputs(strchr(buf, ' ') + 1, stdout);
            if (strcmp(strchr(buf, ' ') + 1, "200 OK\r\n"))
                exit(1);
        }
        if (strstr(buf, "Content-Length:") == buf) {
            *strchr(buf, '\r') = ' ';
            j = atoi(strchr(buf, ' ') + 1);
            l = j / 100;
        }
    }
    for (i = 0, k = 0, m = 0; i < j; i++, k++) {
        recv(sock, &c, 1, 0);
        fputc(c, f);
        cr();
        printf("Progress: %d%c      Downloaded %d / %d bytes", m, '%', i, j);
        if (k == l) {
            m++;
            k = 0;
        }
    }
    fclose(f);
    putchar('\n');

#if defined(_WIN32)
    closesocket(sock);
    WSACleanup();
#elif defined(linux)
    close(sock);
#endif
    return 0;
}