#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <netdb.h>

#include <sys/types.h>

#include <arpa/inet.h>

#include <sys/socket.h>

//下载目标文件 : http://ftp.gnu.org/gnu/bc/bc-1.03.tar.gz

#define HOST_ADDR "ftp.gnu.org"

#define FILE_PATH "/gnu/bc/bc-1.03.tar.gz"

#define FILE_NAME "bc-1.03.tar.gz"

void write_to_socket(int socketfd, const char* str)

{

    write(socketfd, str, strlen(str));

}

int main(void)

{

    char* pstr = NULL;

    int sk_fd = ;

    int size = ;

    int sum = ;

    unsigned long filesize = ;

    FILE* fp = NULL;

    FILE* newfp = NULL;

    struct sockaddr_in sk_addr;

    struct hostent *phost = NULL;

    char buf[] = {};

    float processbar = 0.0f;

    // create TCP socket

    sk_fd = socket(AF_INET, SOCK_STREAM, );

    if (sk_fd < )

    {

        perror("socket failed");

        exit();

    }

    phost = gethostbyname(HOST_ADDR);

    memset(&sk_addr, 0x00, sizeof(sk_addr));

    sk_addr.sin_family = AF_INET;

    sk_addr.sin_port = htons();

    sk_addr.sin_addr.s_addr = ((struct in_addr *)phost->h_addr)->s_addr;

    if (connect(sk_fd, (struct sockaddr *)&sk_addr, sizeof(sk_addr)) < )

    {

        perror("connect failed");

        close(sk_fd);

        exit();

    }

    write_to_socket(sk_fd, "GET "FILE_PATH" HTTP/1.1\r\n");

    write_to_socket(sk_fd, "Accept: */*\r\n");

    write_to_socket(sk_fd, "Host: "HOST_ADDR"\r\n");

    write_to_socket(sk_fd, "Connection: Keep-Alive\r\n");

    write_to_socket(sk_fd, "\r\n");

    shutdown(sk_fd, SHUT_WR);    

    fp = fdopen(sk_fd, "r");

    newfp = fopen(FILE_NAME, "w+");

    memset(buf, 0x00, sizeof(buf));

    while (fgets(buf, , fp))

    {

        printf("%s\n", buf);

        if (filesize != ) /* find CRLF */

        {

            if ( == strlen(buf))

            {

                break;

            }

        }

        else /* get file size */

        {

            pstr = strstr(buf, "Content-Length:");

            if (pstr != NULL)

            {

                pstr = strchr(pstr, ':');

                pstr++;

                filesize = strtoul(pstr, NULL, );

                printf("filesize = %lu\n", filesize);

            }

        }

        memset(buf, 0x00, sizeof(buf));

    }

    while ()

    {

        size = fread(buf, , , fp);

        sum += size;

        if ( == size)

        {

            break;

        }

        size = fwrite(buf, , size, newfp);

        processbar = (float)sum / (float)filesize;

        printf("%6d/%lu[%2.1f]\n", sum, filesize, processbar * );

    }

    fclose(fp);

    fclose(newfp);

    return ;

}