linux C 根据域名获取http响应报文，C语言HTTP请求GET。

Tue, 26 Oct 2010 05:28:32 +0000

今天没事写了个小demo, 根据域名获取http响应报文, 程序也不是很完善
其实主要是要练习一下非阻塞I/O处理.

上代码:

/*
* Author: looyao
*/

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

static int set_fl(int fd, int flags)
{
int val;

if ((val = fcntl(fd,F_GETFL,0)) < 0) {
printf("fcntl F_GETFL error\n");
return -1;
}

val |= flags;

if (fcntl(fd,F_SETFL,val) < 0) {
printf("fcntl F_SETFL error\n");
return -1;
}

return 0;
}

void timeout()
{
printf("time out\n");
exit(0);
}

int main(int argc, char **argv)
{
int sockfd;
struct sockaddr_in servaddr;
struct hostent *host;
char *msg = strdup("GET / HTTP/1.1\r\nHOST: ");
char rbuf[32], res_header[1024];
char *host_ip, *ptr, *pos;
int ntowrite, nwrite, nread, nread_res_header = 0, content_length, nread_content_length = 0;

signal(SIGALRM, timeout);

if (argc < 2) {
printf("请输入域名参数\n");
exit(0);
} else if (argc > 2) {
printf("输入的参数过多\n");
exit(0);
}

msg = realloc(msg, strlen(msg) + strlen(argv[1]) + sizeof("\r\n\r\n"));
sprintf(msg + strlen(msg), "%s\r\n\r\n", argv[1]);

sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) {
perror("socket");
exit(0);
}

host = gethostbyname(argv[1]);
if (host == NULL) {
printf("无法获取此域名IP\n");
goto END;
}

host_ip = inet_ntoa(*((struct in_addr *)host->h_addr));

bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(80);
inet_pton(AF_INET, host_ip, &servaddr.sin_addr);
if( connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0) {
perror("connect");
exit(0);
}

if (set_fl(sockfd, O_NONBLOCK) < 0) {
printf("set nonblock error");
goto END;
}

ntowrite = strlen(msg);
ptr = msg;
alarm(10);
while (ntowrite > 0) {
nwrite = write(sockfd, ptr, ntowrite);
if (nwrite <= 0) {
perror("write:");
goto END;
}
ptr += nwrite;
ntowrite -= nwrite;
}
alarm(0);

/* read response header */
ptr = res_header;
alarm(10);
while (1) {
errno = 0;
nread = read(sockfd, ptr, sizeof(res_header) - nread_res_header);
if(nread < 0){
if(errno == EAGAIN){
continue;
}
perror("read");
goto END;
}
nread_res_header += nread;
ptr += nread;
if((pos = strstr(res_header, "\r\n\r\n")) != NULL || nread_res_header == sizeof(res_header)){
break;
}
}
alarm(0);

if (!(pos = strstr(res_header, "Content-Length:"))) {
printf("响应报文错误");
goto END;
} else {
pos += 16;
if (!(ptr = strstr(pos, "\r\n"))) {
printf("响应报文错误");
goto END;
}
char buf[10];
snprintf(buf, (ptr - pos) > 10 ? 10 : (ptr - pos) + 1, "%s", pos);
content_length = atoi(buf);
}

write(STDOUT_FILENO, res_header, nread_res_header);
if ((pos = strstr(ptr, "\r\n\r\n"))) {
pos += 4;
nread_content_length = nread_res_header - (pos - res_header);
} else {
/* 此处有bug, 如果响应头很长, 没有读到\r\n\r\n, 但是, 先这样吧 :D */
goto END;
}

alarm(10);
while (1) {
errno = 0;
memset(rbuf, 0, sizeof(rbuf));
nread = read(sockfd, rbuf, sizeof(rbuf));
if (nread < 0) {
if (errno == EAGAIN) {
continue;
}
perror("read");
goto END;
}
write(STDOUT_FILENO, rbuf, nread);
nread_content_length += nread;
if (nread_content_length >= content_length){
break;
}
}
alarm(0);

END:
close(sockfd);
free(msg);
return 0;
}

编译后运行 ./demo www.baidu.com
响应的报文如下:
HTTP/1.1 200 OK
Date: Thu, 29 Apr 2010 08:57:48 GMT
Server: BWS/1.0
Content-Length: 3521
Content-Type: text/html;charset=gb2312
Cache-Control: private
Expires: Thu, 29 Apr 2010 08:57:48 GMT
Set-Cookie: BAIDUID=4573491A3ED9E0B16CA37586CFB9460E:FG=1; expires=Thu, 29-Apr-40 08:57:48 GMT; path=/; domain=.baidu.com
P3P: CP=" OTI DSP COR IVA OUR IND COM "

百度一下，你就知道

新闻　网页　贴吧　知道　 MP3　图片　视频　地图

空间　百科　 hao123 | 更多>>

把百度设为主页

加入百度推广 | 搜索风云榜 | 关于百度 | About Baidu

非阻塞要不断的轮询, 浪费了CPU时间, 但是说与使用select机制相比, 到底那个机制更快,
也需要看情况, 我会继续试验.
对于read的结束条件, 具体看通信的协议.
http协议主要是看Content-Length, 还有一种是Transfer-Encoding: chunked,
我这个小demo实现的是根据Content-Length判断read结束.
over, 未完待续...
来源：http://hi.baidu.com/teng0210/blog/item/4955e8946e992b47d0135e2a.html

C语言HTTP请求GET，因对《所谓黑客揭秘》，大家都攻击代码的要求。所以我开始了为期两周的C/C++学习。由于没有任何C/C++基础，而是临时突击，所以代码肯定漏洞甚多，请观者见谅。同时欢迎拍砖或者支出代码错误，以求大家共同进步。：

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

void DownLoad(char *url){
  WSADATA WsaData;
  SOCKET socketfd;
  SOCKADDR_IN addr;
  HOSTENT *pURL;
  int i=0;
  char myurl[BUFSIZ];
  char *pHost =0,* pGet =0;
  char host[BUFSIZ],GET[BUFSIZ];
  char Header[BUFSIZ];
  FILE * pf;

static char text[BUFSIZ];

if (WSAStartup(MAKEWORD(2,2),&WsaData))
  {
    printf("The socket failed");
    return;
  }
  strcpy(myurl,url);

for (i=0,pHost= myurl;*pHost!='/'&&*pHost!='/0';pHost++,i++){
    host[i] = *pHost;
  }
  host[i]='/0';
  strcpy(GET,pHost);
  strnset(Header,'/0',BUFSIZ);

socketfd = socket(PF_INET,SOCK_STREAM,IPPROTO_TCP);
  pURL = gethostbyname(host);

addr.sin_addr.s_addr = *((unsigned long *)pURL->h_addr);
  addr.sin_family = AF_INET;
  addr.sin_port = htons(80);

strcat(Header,"GET / ");
  strcat(Header,GET);
  strcat(Header,"HTTP/1.1/r/n");
  strcat(Header,"Accept: */*/r/n");
  strcat(Header,"Accept-Language: zh-cn/r/n");
  strcat(Header,"User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022; InfoPath.2)/r/n");
  //strcat(Header,"Accept-Encoding: gzip, deflate/r/n");
  strcat(Header,"Host: ");
  strcat(Header,host);
  strcat(Header,"/r/nConnection: Keep-Alive/r/n");
  
  strcat(Header,"/r/n/r/n");
  
  connect(socketfd,(SOCKADDR *)&addr,sizeof(addr));
  send(socketfd,Header,strlen(Header),0);
  printf("%s",Header);
  pf = fopen("1.txt","w");
  while(recv(socketfd,text,BUFSIZ,0)>0){
    printf("%s",text);
    fputs(text,pf);
    strnset(text,'/0',BUFSIZ);
  }
  fclose(pf);
  closesocket(socketfd);
  WSACleanup();

}
int main(){
  char a[256];
  printf("http://");
  scanf("%s",a);
  DownLoad(a);
}

来自：http://blog.csdn.net/aofengdaxia/article/details/5984431

[评论] linux C 根据域名获取http响应报文，C语言HTTP请求GET。

Thu, 01 Jan 1970 00:00:00 +0000

向东博客 专注WEB应用 构架之美 --- 构架之美，在于尽态极妍 | 应用之美，在于药到病除

linux C 根据域名获取http响应报文，C语言HTTP请求GET。

[评论] linux C 根据域名获取http响应报文，C语言HTTP请求GET。

向东博客专注WEB应用构架之美 --- 构架之美，在于尽态极妍 | 应用之美，在于药到病除