#include <stdio.h>//printf
#include <string.h>//字符串处理
#include <sys/socket.h>//套接字
#include <arpa/inet.h>//ip地址处理
#include <fcntl.h>//open系统调用
#include <unistd.h>//write系统调用
#include <netdb.h>//查询DNS
#include <stdlib.h>//exit函数
#include <sys/stat.h>//stat系统调用获取文件大小
#include <sys/time.h>//获取下载时间
//下载地址 http://dldir1.qq.com/qqfile/qq/QQ7.9/16638/QQ7.9.exe
struct HTTP_RES_HEADER//保持相应头信息
{
int status_code;//HTTP/1.1 '200' OK
char content_type[128];//Content-Type: application/gzip
long content_length;//Content-Length: 11683079
};
void parse_url(const char *url, char *host, int *port, char *file_name)
{
/*通过url解析出域名, 端口, 以及文件名*/
int j = 0;
int start = 0;
*port = 80;
char *patterns[] = {"http://", "https://", NULL};
for (int i = 0; patterns[i]; i++)//分离下载地址中的http协议
if (strncmp(url, patterns[i], strlen(patterns[i])) == 0)
start = strlen(patterns[i]);
//解析域名, 这里处理时域名后面的端口号会保留
for (int i = start; url[i] != '/' && url[i] != '\0'; i++, j++)
host[j] = url[i];
host[j] = '\0';
//解析端口号, 如果没有, 那么设置端口为80
char *pos = strstr(host, ":");
if (pos)
sscanf(pos, ":%d", port);
//删除域名端口号
for (int i = 0; i < (int)strlen(host); i++)
{
if (host[i] == ':')
{
host[i] = '\0';
break;
}
}
//获取下载文件名
j = 0;
for (int i = start; url[i] != '\0'; i++)
{
if (url[i] == '/')
{
if (i != strlen(url) - 1)
j = 0;
continue;
}
else
file_name[j++] = url[i];
}
file_name[j] = '\0';
}
struct HTTP_RES_HEADER parse_header(const char *response)
{
/*获取响应头的信息*/
struct HTTP_RES_HEADER resp;
char *pos = strstr(response, "HTTP/");
if (pos)//获取返回代码
sscanf(pos, "%*s %d", &resp.status_code);
pos = strstr(response, "Content-Type:");
if (pos)//获取返回文档类型
sscanf(pos, "%*s %s", resp.content_type);
pos = strstr(response, "Content-Length:");
if (pos)//获取返回文档长度
sscanf(pos, "%*s %ld", &resp.content_length);
return resp;
}
void get_ip_addr(char *host_name, char *ip_addr)
{
/*通过域名得到相应的ip地址*/
struct hostent *host = gethostbyname(host_name);//此函数将会访问DNS服务器
if (!host)
{
ip_addr = NULL;
return;
}
for (int i = 0; host->h_addr_list[i]; i++)
{
strcpy(ip_addr, inet_ntoa( * (struct in_addr*) host->h_addr_list[i]));
break;
}
}
void progress_bar(long cur_size, long total_size, double speed)
{
/*用于显示下载进度条*/
float percent = (float) cur_size / total_size;
const int numTotal = 50;
int numShow = (int)(numTotal * percent);
if (numShow == 0)
numShow = 1;
if (numShow > numTotal)
numShow = numTotal;
char sign[51] = {0};
memset(sign, '=', numTotal);
printf("\r%.2f%%[%-*.*s] %.2f/%.2fMB %4.0fkb/s", percent * 100, numTotal, numShow, sign, cur_size / 1024.0 / 1024.0, total_size / 1024.0 / 1024.0, speed);
fflush(stdout);
if (numShow == numTotal)
printf("\n");
}
unsigned long get_file_size(const char *filename)
{
//通过系统调用直接得到文件的大小
struct stat buf;
if (stat(filename, &buf) < 0)
return 0;
return (unsigned long) buf.st_size;
}
void download(int client_socket, char *file_name, long content_length)
{
/*下载文件函数*/
long hasrecieve = 0;//记录已经下载的长度
struct timeval t_start, t_end;//记录一次读取的时间起点和终点, 计算速度
int mem_size = 8192;//缓冲区大小8K
int buf_len = mem_size;//理想状态每次读取8K大小的字节流
int len;
//创建文件描述符
int fd = open(file_name, O_CREAT | O_WRONLY, S_IRWXG | S_IRWXO | S_IRWXU);
if (fd < 0)
{
printf("文件创建失败!\n");
exit(0);
}
char *buf = (char *) malloc(mem_size * sizeof(char));
//从套接字流中读取文件流
long diff = 0;
int prelen = 0;
double speed;
while (hasrecieve < content_length)
{
gettimeofday(&t_start, NULL ); //获取开始时间
len = read(client_socket, buf, buf_len);
write(fd, buf, len);
gettimeofday(&t_end, NULL ); //获取结束时间
hasrecieve += len;//更新已经下载的长度
//计算速度
if (t_end.tv_usec - t_start.tv_usec >= 0 && t_end.tv_sec - t_start.tv_sec >= 0)
diff += 1000000 * ( t_end.tv_sec - t_start.tv_sec ) + (t_end.tv_usec - t_start.tv_usec);//us
if (diff >= 1000000)//当一个时间段大于1s=1000000us时, 计算一次速度
{
speed = (double)(hasrecieve - prelen) / (double)diff * (1000000.0 / 1024.0);
prelen = hasrecieve;//清零下载量
diff = 0;//清零时间段长度
}
progress_bar(hasrecieve, content_length, speed);
if (hasrecieve == content_length)
break;
}
}
int main(int argc, char const *argv[])
{
/* 命令行参数: 接收两个参数, 第一个是下载地址, 第二个是文件的保存位置和名字, 下载地址是必须的, 默认下载到当前目录
* 示例: ./download http://www.baidu.com baidu.html
*/
char url[2048] = "127.0.0.1";//设置默认地址为本机,
char host[64] = {0};//远程主机地址
char ip_addr[16] = {0};//远程主机IP地址
int port = 80;//远程主机端口, http默认80端口
char file_name[256] = {0};//下载文件名
if (argc == 1)
{
printf("您必须给定一个http地址才能开始工作\n");
exit(0);
}
else
strcpy(url, argv[1]);
puts("1: 正在解析下载地址...");
parse_url(url, host, &port, file_name);//从url中分析出主机名, 端口号, 文件名
if (argc == 3)
{
printf("\t您已经将下载文件名指定为: %s\n", argv[2]);
strcpy(file_name, argv[2]);
}
puts("2: 正在获取远程服务器IP地址...");
get_ip_addr(host, ip_addr);//调用函数同访问DNS服务器获取远程主机的IP
if (strlen(ip_addr) == 0)
{
printf("错误: 无法获取到远程服务器的IP地址, 请检查下载地址的有效性\n");
return 0;
}
puts("\n>>>>下载地址解析成功<<<<");
printf("\t下载地址: %s\n", url);
printf("\t远程主机: %s\n", host);
printf("\tIP 地 址: %s\n", ip_addr);
printf("\t主机PORT: %d\n", port);
printf("\t 文件名 : %s\n\n", file_name);
//设置http请求头信息
char header[2048] = {0};
sprintf(header, \
"GET %s HTTP/1.1\r\n"\
"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8\r\n"\
"User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537(KHTML, like Gecko) Chrome/47.0.2526Safari/537.36\r\n"\
"Host: %s\r\n"\
"Connection: keep-alive\r\n"\
"\r\n"\
,url, host);
puts("3: 创建网络套接字...");
int client_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (client_socket < 0)
{
printf("套接字创建失败: %d\n", client_socket);
exit(-1);
}
//创建IP地址结构体
struct sockaddr_in addr;
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = inet_addr(ip_addr);
addr.sin_port = htons(port);
//连接远程主机
puts("4: 正在连接远程主机...");
int res = connect(client_socket, (struct sockaddr *) &addr, sizeof(addr));
if (res == -1)
{
printf("连接远程主机失败, error: %d\n", res);
exit(-1);
}
puts("5: 正在发送http下载请求...");
write(client_socket, header, strlen(header));//write系统调用, 将请求header发送给服务器
int mem_size = 4096;
int length = 0;
int len;
char *buf = (char *) malloc(mem_size * sizeof(char));
char *response = (char *) malloc(mem_size * sizeof(char));
//每次单个字符读取响应头信息
puts("6: 正在解析http响应头...");
while ((len = read(client_socket, buf, 1)) != 0)
{
if (length + len > mem_size)
{
//动态内存申请, 因为无法确定响应头内容长度
mem_size *= 2;
char * temp = (char *) realloc(response, sizeof(char) * mem_size);
if (temp == NULL)
{
printf("动态内存申请失败\n");
exit(-1);
}
response = temp;
}
buf[len] = '\0';
strcat(response, buf);
//找到响应头的头部信息
int flag = 0;
for (int i = strlen(response) - 1; response[i] == '\n' || response[i] == '\r'; i--, flag++);
if (flag == 4)//连续两个换行和回车表示已经到达响应头的头尾, 即将出现的就是需要下载的内容
break;
length += len;
}
struct HTTP_RES_HEADER resp = parse_header(response);
printf("\n>>>>http响应头解析成功:<<<<\n");
printf("\tHTTP响应代码: %d\n", resp.status_code);
if (resp.status_code != 200)
{
printf("文件无法下载, 远程主机返回: %d\n", resp.status_code);
return 0;
}
printf("\tHTTP文档类型: %s\n", resp.content_type);
printf("\tHTTP主体长度: %ld字节\n\n", resp.content_length);
printf("7: 开始文件下载...\n");
download(client_socket, file_name, resp.content_length);
printf("8: 关闭套接字\n");
if (resp.content_length == get_file_size(file_name))
printf("\n文件%s下载成功! ^_^\n\n", file_name);
else
{
remove(file_name);
printf("\n文件下载中有字节缺失, 下载失败, 请重试!\n\n");
}
shutdown(client_socket, 2);//关闭套接字的接收和发送
return 0;
}
运行效果: