转载自：c/s模式Linux下用c语言实现发送http请求
/******* http客户端程序 httpclient.c ************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <unistd.h>
#include <netinet/in.h>
#include <limits.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <ctype.h>
//////////////////////////////httpclient.c 开始///////////////////////////////////////////
/********************************************
功能：搜索字符串右边起的第一个匹配字符
********************************************/
char* Rstrchr(char* s, char x)
{
int i = strlen(s);
if(!(*s))
{
return 0;
}
while(s[i-1])
{
if(strchr(s+(i-1), x))
{
return (s+(i-1));
}
else
{
i--;
}
}
return 0;
}
/********************************************
功能：把字符串转换为全小写
********************************************/
void ToLowerCase(char* s)
{
while(*s && *s!='\0' )
{
*s=tolower(*s++);
}
*s = '\0';
}
/**************************************************************
功能：从字符串src中分析出网站地址和端口，并得到用户要下载的文件
***************************************************************/
void GetHost(char* src, char* web, char* file, int* port)
{
char* pA;
char* pB;
memset(web, 0, sizeof(web));
memset(file, 0, sizeof(file));
*port = 0;
if(!(*src))
{
return;
}
pA = src;
if(!strncmp(pA, "http://", strlen("http://")))
{
pA = src+strlen("http://");
}
else if(!strncmp(pA, "https://", strlen( "https://")))
{
pA = src+strlen( "https://");
}
pB = strchr(pA, '/');
if(pB)
{
memcpy(web, pA, strlen(pA)-strlen(pB));
if(pB+1)
{
memcpy(file, pB+1, strlen(pB)-1);
file[strlen(pB)-1] = 0;
}
}
else
{
memcpy(web, pA, strlen(pA));
}
if(pB)
{
web[strlen(pA) - strlen(pB)] = 0;
}
else
{
web[strlen(pA)] = 0;
}
pA = strchr(web, ':');
if(pA)
{
*port = atoi(pA + 1);
}
else
{
*port = 80;
}
}
/*********************************************************************
*filename: httpclient.c
*purpose: HTTP协议客户端程序，可以用来下载网页
*********************************************************************/
int main(int argc, char *argv[])
{
int sockfd = 0;
char buffer[1024] = "";
struct sockaddr_in server_addr;
struct hostent *host;
int portnumber = 0;
int nbytes = 0;
char host_addr[256] = "";
char host_file[1024] = "";
FILE *fp;
char request[1024] = "";
int send = 0;
int totalsend = 0;
int i = 0;
char *pt;
if(argc!=2)
{
fprintf(stderr, "Usage:%s web-address\a\n ",argv[0]);
exit(1);
}
printf( "parameter.1 is: %s\n ", argv[1]);
//ToLowerCase(argv[1]);/*将参数转换为全小写*/
//printf( "lowercase parameter.1 is: %s\n ", argv[1]);
GetHost(argv[1], host_addr, host_file, &portnumber);/*分析网址、端口、文件名等*/
printf( "webhost:%s\n ", host_addr);
printf( "hostfile:%s\n ", host_file);
printf( "portnumber:%d\n\n ", portnumber);
if((host=gethostbyname(host_addr)) == NULL)/*取得主机IP地址*/
{
fprintf(stderr, "Gethostname error, %s\n ", strerror(errno));
exit(1);
}
/* 客户程序开始建立 sockfd描述符 */
if((sockfd=socket(AF_INET,SOCK_STREAM,0)) == -1)/*建立SOCKET连接*/
{
fprintf(stderr, "Socket Error:%s\a\n ",strerror(errno));
exit(1);
}
/* 客户程序填充服务端的资料 */
bzero(&server_addr,sizeof(server_addr));
server_addr.sin_family=AF_INET;
server_addr.sin_port=htons(portnumber);
server_addr.sin_addr=*((struct in_addr*)host->h_addr);
/* 客户程序发起连接请求 */
if(connect(sockfd, (struct sockaddr*)(&server_addr), sizeof(struct sockaddr)) == -1)/*连接网站*/
{
fprintf(stderr, "Connect Error:%s\a\n ",strerror(errno));
exit(1);
}
sprintf(request, "GET /%s HTTP/1.1\r\nAccept: */*\r\nAccept-Language: zh-cn\r\n\
User-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)\r\n\
Host: %s:%d\r\nConnection: Close\r\n\r\n ", host_file, host_addr, portnumber);
printf( "%s\n", request);/*准备request，将要发送给主机*/
/*取得真实的文件名*/
if(host_file && *host_file)
{
pt = Rstrchr(host_file, '/');
}
else
{
pt = 0;
}
/*发送http请求request*/
send = 0;
totalsend = 0;
nbytes=strlen(request);
while(totalsend < nbytes)
{
send = write(sockfd, request+totalsend, nbytes-totalsend);
if(send == -1)
{
printf( "send error!%s\n ", strerror(errno));
exit(0);
}
totalsend += send;
printf("%d bytes send OK!\n ", totalsend);
}
printf( "\nThe following is the response header:\n ");
i=0;
/* 连接成功了，接收http响应，response */
while((nbytes=read(sockfd,buffer,1))==1)
{
if(i < 4)
{
if(buffer[0] == '\r' || buffer[0] == '\n')
{
i++;
}
else
{
i = 0;
}
printf( "%c ", buffer[0]);/*把http头信息打印在屏幕上*/
}
}
// printf("\n\nresponse = %s\n", buffer);
/* 结束通讯 */
close(sockfd);
exit(0);
}
//////////////////////////////httpclient.c 结束///////////////////////////////////////////