c语言实现http下载器的方法
一、介绍
最近做ota升级需要用到http下载，所以写了一下http下载器
实现流程
1、解析url网址的域名和文件名
2、获取ip地址
3、构建http请求头发送到服务器
4、解析回复
5、下载文件
环境ubuntu linux
c语言
开源链接
main.c
#include <stdio.h>
#include "http_download.h"
int main(int argc, char const *argv[])
{
if (argc == 1)
{
printf("Input a valid URL \n");
exit(0);
}
else
{
http_download_file(argv[1]);
}
return 0;
}
http_download.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <fcntl.h>
#include "tcp.h"
typedef struct {
int status_code;//HTTP/1.1 '200' OK
char content_type[128];//Content-Type: application/gzip
long content_length;//Content-Length: 11683079
char file_name[256];
}resp_header_def;
resp_header_def resp;//头信息
#if 0
下载分为以下几个过程
1、解析出下载地址中的域名和文件名
2、通过域名获取服务器的IP地址
3、与目标服务器建立连接
4、构建http请求头并将其发送到服务器
5、等待服务器响应然后接收响应头
6、解析响应头, 判断返回码, 分离开响应头, 并且响应的正文内容以字节形式写入文件, 正文内容与头部用两个\n\r分开
#endif
#define print_LOG(format, ...) {\
printf(format, ##__VA_ARGS__);}
//解析网址
//输入url，输出域名、端口、文件名
static int Parsing_urls(char *url, char *domain, int *port, char *filename)
{
int i,j,start;
char *patterns[] = {"http://", "https://", NULL};
*port = 80;
//解析域名，就是http://或者https://到/的内容
for(i = 0; patterns[i]; i++)
{
if(strncmp(url, patterns[i], strlen(patterns[i])) == 0)
{
start = strlen(patterns[i]);
}
}
//复制域名
j = 0;
for ( i = start; url[i] != '/' && url[i] != '\0'; i++,j++)
{
domain[j] = url[i];
}
domain[i] = '\0';
//解析端口,冒号后面就是端口
char pos = strstr(domain, ":");
if(pos)
{
sscanf(pos, ":%d", port);
}
//如果有端口，需要删掉
for ( i = 0; i < (int)strlen(domain); i++)
{
if(domain[i] == ':')
{
domain[i] = '\0';
break;
}
}
//解析下载文件名,/后面就是文件名
j = 0;
for ( i = start; url[i] != '\0'; i++)
{
if(url[i] == '/')
{
j = i + 1;
memcpy(filename, &url[j], strlen(&url[j]));
}
}
i = strlen(&url[j]);
filename[i] = '\0';
return 0;
}
//通过域名获取ip
static int Domain_to_ip(char *domain, char *ip)
{
int i;
struct hostent *host = gethostbyname(domain);
if(host == 0)
{
*ip = NULL;
return -1;
}
//找到不为空的地址
for ( i = 0; host->h_addr_list[i]; i++)
{
strcpy(ip, inet_ntoa( * (struct in_addr*) host->h_addr_list[i]));
break;
}
return 0;
}
//构建请求头信息
static int Set_request_headers(char *header, char *url, char *domain)
{
int ret = 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:close\r\n"\
"\r\n"\
,url, domain);
ret = strlen(header);
return ret;
}
static char *get_response()
{
int len, lencnt = 0,mem_size = 4096;
char *rcvbuff = (char *)malloc( mem_size*sizeof(char) );
char *response = (char *)malloc( mem_size*sizeof(char) );
while((len = tcp_client_rcv(rcvbuff, 1)) != 0)
{
//动态调整缓存大小
if((lencnt + len) > mem_size)//判断缓存是否超限
{
//重新分配内存
mem_size *= 2;
char *tmp = (char *)realloc(response, mem_size*sizeof(char));
if(tmp == NULL)
{
printf("realloc fail\n");
exit(-1);
}
response = tmp;
}
rcvbuff[len] = '\0';
strcat(response, rcvbuff);
//找到响应头的头部信息, 两个"\n\r"为分割点
int flag = 0;
int i = strlen(response) - 1;
for (; response[i] == '\n' || response[i] == '\r';
i--, flag++);
{
if (flag == 4)//最多找4次，没找到
break;
}
lencnt += len;
}
free(rcvbuff);
return response;
}
//获取回复头的信息
static int get_resp_header(const char *response, resp_header_def *resp)
{
//查找HTTP/
char *pos = strstr(response, "HTTP/");
if (pos)
sscanf(pos, "%*s %d", &resp->status_code);//返回状态码
pos = strstr(response, "Content-Type:");//返回内容类型
if (pos)
sscanf(pos, "%*s %s", resp->content_type);
pos = strstr(response, "Content-Length:");//内容的长度(字节)
if (pos)
sscanf(pos, "%*s %ld", &resp->content_length);
return 0;
}
//打印进度
int progress_bar(int x)
{
int i;
char tmp[100] = {0};
static int x_old = 0;
if(x == x_old)
{
return 0;
}
x_old = x;
i = x/2;
if(i > 50)
i = 50;
memset(tmp, '=', i);
printf("\r%d%[%s]", x, tmp);
fflush(stdout);//立刻输出
return 0;
}
static int download_writefile()
{
int length = 0;
int mem_size = 4096;//mem_size might be enlarge, so reset it
int buf_len = mem_size;//read 4k each time
int len = 0;
int fd = open(resp.file_name, O_CREAT | O_WRONLY, S_IRWXG | S_IRWXO | S_IRWXU);
if (fd < 0)
{
print_LOG("Create file failed\n");
exit(0);
}
//申请4k缓存
char *buf = (char *)malloc(mem_size * sizeof(char));
//读取文件
while ((len = tcp_client_rcv(buf, buf_len)) != 0 && length < resp.content_length)
{
write(fd, buf, len);
length += len;
progress_bar((length*100/resp.content_length));
}
if (length == resp.content_length)
{
print_LOG("\nDownload successful ^_^\n\n");
}
else
{
print_LOG("Finished length:%d,resp.content_length:%d\n",
length, resp.content_length);
}
close(fd);
return 0;
}
//http下载文件函数
int http_download_file(char *url)
{
//char url[2048] = "127.0.0.1";
char domain[64] = {0};
char ip_addr[16] = {0};
int port = 80;
char file_name[256] = {0};
char header[2048] = {0};
char *response = 0;
//解析域名
Parsing_urls(url, domain, &port, file_name);
//解析ip
Domain_to_ip(domain, ip_addr);
print_LOG("download:\n url:%s\n domain:%s\n ip:%s\n port:%d\n filename:%s\n",
url, domain, ip_addr, port, file_name);
//发送下载请求
Set_request_headers(header, url, domain);
if(tcp_client_init(ip_addr, port) == -1)
{
print_LOG("connect server fail\n");
return -1;
}
tcp_client_send(header, strlen(header));
print_LOG("\nsend request\n");
//print_LOG("send request:%s\n", header);
//解析回复
response = get_response();
get_resp_header(response, &resp);
print_LOG("response:%s\n", response);
free(response);
strcpy(resp.file_name, file_name);
print_LOG("\nres:\n content_length:%d\n file_name:%s\n Content-Type:%s\n",
resp.content_length,
resp.file_name,
resp.content_type);
//下载文件
print_LOG("\ndownload %s start ...\n", resp.file_name);
download_writefile();
return 0;
}
download.h
#ifndef __HTTP_DOWNLOAD_H #define __HTTP_DOWNLOAD_H int http_download_file(char *url); #endif
tcp.c
//-------tcp相关头文件------
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h> //close()
static int socket_fd = 0;
//tcp_client_init()
//1、创建socket
//2、配置为客户端
//3、配置要连接的服务器ip和端口以及协议类型
//4、连接服务器
//5、收发数据
//6、关闭连接
int tcp_client_init(char *ip, int port)
{
int ret;
//1 2
socket_fd = socket(AF_INET, SOCK_STREAM, 0);
if(socket_fd == -1)
{
printf("create socket fail\n");
return -1;
}
//3
struct sockaddr_in servaddr;
servaddr.sin_family = AF_INET;//IPv4协议
servaddr.sin_port = htons(port);//服务器端口号
servaddr.sin_addr.s_addr = inet_addr(ip);//设置服务器
//4
ret = connect(socket_fd, &servaddr, sizeof(servaddr));
if(ret == -1)
{
printf("connect %s fail\n", ip);
return -1;
}
}
//tcp_client_send()
int tcp_client_send(char *buff, int len)
{
int ret = 0;
ret = write(socket_fd, buff, len);
return ret;
}
//tcp_client_rcv()
int tcp_client_rcv(char *buff, int len)
{
int ret;
ret = read(socket_fd, buff, len);
return ret;
}
//tcp_client_close()
int tcp_client_close()
{
close(socket_fd);
}
#define CLENT_NUM 2
struct sockaddr_in sSever_c_sd[CLENT_NUM];
static int socket_s_fd = 0;
static int socket_c_fd[CLENT_NUM] = {0};
//tcp_server_init()
#if 0
1、创建socket
2、设置本地ip和端口以及协议类型
3、绑定
4、监听
5、等待客户端连接
6、收发数据
7、关闭连接
#endif
int tcp_server_init(int port)
{
int ret;
//1
socket_s_fd = socket(AF_INET, SOCK_STREAM, 0);
if(socket_s_fd == -1)
{
printf("create socket fail\n");
return -1;
}
else
{
printf("create socket ok\n");
}
//2
struct sockaddr_in local_addr,c_addr;
local_addr.sin_family = AF_INET;//IPv4协议
local_addr.sin_port = htons(port);//服务器端口号
local_addr.sin_addr.s_addr = INADDR_ANY;//设置服务器ip
//3
ret = bind(socket_s_fd, &local_addr, sizeof(local_addr));
if(ret == -1)
{
printf("bind fail\n");
close(socket_s_fd);
return -1;
}
else
{
printf("bind ok\n");
}
//4
ret = listen(socket_s_fd, 3);
if(ret == -1)
{
printf("listen fail\n");
close(socket_s_fd);
return -1;
}
else
{
printf("listen ok\n");
}
//5
socklen_t addrlen = 0;
while(1)
{
printf("wait client conect\n");
socket_c_fd[0] = accept(socket_s_fd, &c_addr, &addrlen);
if(addrlen != 0)
break;
sleep(1);
}
printf("client conect\n");
return 0;
}
//tcp_server_send()
int tcp_server_send(char c, char *buff, int len)
{
write(socket_c_fd[c], buff, len);
}
//tcp_server_rcv()
int tcp_server_rcv(char c, char *buff, int len)
{
int ret;
ret = read(socket_c_fd[c], buff, len);
return ret;
}
//tcp_server_close()
int tcp_server_close()
{
close(socket_s_fd);
}
tcp.h
#ifndef __TCP_H #define __TCP_H int tcp_client_init(char *ip, int port); int tcp_client_send(unsigned char *buff, int len); int tcp_client_rcv(unsigned char *buff, int len); int tcp_client_close(); int tcp_server_init( int port); int tcp_server_send(char c, unsigned char *buff, int len); int tcp_server_rcv(char c, unsigned char *buff, int len); int tcp_server_close(); #endif
编译脚本
rm -rf main sscom32.zip gcc main.c http_download.c tcp.c -o main -w ./main http://xzd.197946.com/sscom32.zip
测试效果
http://xzd.197946.com/sscom32.zip
到此这篇关于c语言实现http下载器的文章就介绍到这了,更多相关c语言http下载器内容请搜索海外IDC网以前的文章或继续浏览下面的相关文章希望大家以后多多支持海外IDC网！