HTTP是基于IP/TCP加上了网络请求的固定格式， 比如：
method
URL
Content-host
Content-Type
Content-Length
实现GET请求
把组合成的数据按照固定的格式发送给服务器， 服务器解析相应的格式， 然后返回服务器数据：
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <time.h>
#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define IPSTR "42.121.252.58" //服务器IP地址;
#define PORT 80
#define BUFSIZE 1024
int main(int argc, char **argv)
{
int sockfd, ret, i, h;
struct sockaddr_in servaddr;
char str1[4096], str2[4096], buf[BUFSIZE], *str;
socklen_t len;
fd_set t_set1;
struct timeval tv;
//创建套接字
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
printf("创建网络连接失败,本线程即将终止---socket error!\n");
exit(0);
};
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
if (inet_pton(AF_INET, IPSTR, &servaddr.sin_addr) <= 0 ){
printf("创建网络连接失败,本线程即将终止--inet_pton error!\n");
exit(0);
};
if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0){
printf("连接到服务器失败,connect error!\n");
exit(0);
}
printf("与远端建立了连接\n");
memset(str2, 0, 4096);
strcat(str2, "theDataToPost");
str=(char *)malloc(128);
len = strlen(str2);
sprintf(str, "%d", len);
memset(str1, 0, 4096);
strcat(str1, "GET /ymnets/p/6255674.html HTTP/1.1\n");
strcat(str1, "Host: www.cnblogs.com\n");
strcat(str1, "Content-Type: text/html\n");
strcat(str1, "Content-Length: ");
strcat(str1, str);
strcat(str1, "\n\n");
strcat(str1, str2);
strcat(str1, "\r\n\r\n");
printf("%s\n",str1);
ret = write(sockfd,str1,strlen(str1));
if (ret < 0) {
printf("发送失败！错误代码是%d，错误信息是'%s'\n",errno, strerror(errno));
exit(0);
}else{
printf("消息发送成功，共发送了%d个字节！\n\n", ret);
}
FD_ZERO(&t_set1);
FD_SET(sockfd, &t_set1);
while(1){
sleep(2);
tv.tv_sec= 0;
tv.tv_usec= 0;
h= 0;
printf("--------------->1");
h= select(sockfd +1, &t_set1, NULL, NULL, &tv);
printf("--------------->2");
//if (h == 0) continue;
if (h < 0) {
close(sockfd);
printf("在读取数据报文时SELECT检测到异常，该异常导致线程终止！\n");
return -1;
};
if (h > 0){
memset(buf, 0, 4096);
i= read(sockfd, buf, 4095);
if (i==0){
close(sockfd);
printf("读取数据报文时发现远端关闭，该线程终止！\n");
return -1;
}
printf("%s\n", buf);
}
}
close(sockfd);
return 0;
}
实现POST请求：
C实现POST请求参考代码， 只要把请求类型从GET改为POST， 然后把请求的数据代入到请求头中即可：
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <time.h>
#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define IPSTR "61.147.124.120"
#define PORT 80
#define BUFSIZE 1024
int main(int argc, char **argv)
{
int sockfd, ret, i, h;
struct sockaddr_in servaddr;
char str1[4096], str2[4096], buf[BUFSIZE], *str;
socklen_t len;
fd_set t_set1;
struct timeval tv;
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
printf("创建网络连接失败,本线程即将终止---socket error!\n");
exit(0);
};
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
if (inet_pton(AF_INET, IPSTR, &servaddr.sin_addr) <= 0 ){
printf("创建网络连接失败,本线程即将终止--inet_pton error!\n");
exit(0);
};
if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0){
printf("连接到服务器失败,connect error!\n");
exit(0);
}
printf("与远端建立了连接\n");
memset(str2, 0, 4096);
strcat(str2, "qqCode=287101329");
str=(char *)malloc(128);
len = strlen(str2);
sprintf(str, "%d", len);
memset(str1, 0, 4096);
strcat(str1, "POST /webservices/qqOnlineWebService.asmx/qqCheckOnline HTTP/1.1\n");
strcat(str1, "Host: www.webxml.com.cn\n");
strcat(str1, "Content-Type: application/x-www-form-urlencoded\n");
strcat(str1, "Content-Length: ");
strcat(str1, str);
strcat(str1, "\n\n");
//str2的值为post的数据
strcat(str1, str2);
strcat(str1, "\r\n\r\n");
printf("%s\n",str1);
ret = write(sockfd,str1,strlen(str1));
if (ret < 0) {
printf("发送失败！错误代码是%d，错误信息是'%s'\n",errno, strerror(errno));
exit(0);
}else{
printf("消息发送成功，共发送了%d个字节！\n\n", ret);
}
FD_ZERO(&t_set1);
FD_SET(sockfd, &t_set1);
while(1){
sleep(2);
tv.tv_sec= 0;
tv.tv_usec= 0;
h= 0;
printf("--------------->1");
h= select(sockfd +1, &t_set1, NULL, NULL, &tv);
printf("--------------->2");
//if (h == 0) continue;
if (h < 0) {
close(sockfd);
printf("在读取数据报文时SELECT检测到异常，该异常导致线程终止！\n");
return -1;
};
if (h > 0){
memset(buf, 0, 4096);
i= read(sockfd, buf, 4095);
if (i==0){
close(sockfd);
printf("读取数据报文时发现远端关闭，该线程终止！\n");
return -1;
}
printf("%s\n", buf);
}
}
close(sockfd);
return 0;
}
POST请求的方式可以再改改：
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <time.h>
#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define IPSTR "61.147.124.120"
#define PORT 80
#define BUFSIZE 1024
int main(int argc, char **argv)
{
int sockfd, ret, i, h;
struct sockaddr_in servaddr;
char str1[4096], str2[4096], buf[BUFSIZE], *str;
socklen_t len;
fd_set t_set1;
struct timeval tv;
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
printf("创建网络连接失败,本线程即将终止---socket error!\n");
exit(0);
};
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
if (inet_pton(AF_INET, IPSTR, &servaddr.sin_addr) <= 0 ){
printf("创建网络连接失败,本线程即将终止--inet_pton error!\n");
exit(0);
};
if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0){
printf("连接到服务器失败,connect error!\n");
exit(0);
}
printf("与远端建立了连接\n");
memset(str2, 0, 4096);
strcat(str2, "qqCode=287101329");
str=(char *)malloc(128);
len = strlen(str2);
sprintf(str, "%d", len);
memset(str1, 0, 4096);
strcat(str1, "POST /webservices/qqOnlineWebService.asmx/qqCheckOnline HTTP/1.1\n");
strcat(str1, "Host: www.webxml.com.cn\n");
strcat(str1, "Content-Type: application/x-www-form-urlencoded\n");
strcat(str1, "Content-Length: ");
strcat(str1, str);
strcat(str1, "\n\n");
//str2的值为post的数据
strcat(str1, str2);
strcat(str1, "\r\n\r\n");
printf("%s\n",str1);
ret = write(sockfd,str1,strlen(str1));
if (ret < 0) {
printf("发送失败！错误代码是%d，错误信息是'%s'\n",errno, strerror(errno));
exit(0);
}else{
printf("消息发送成功，共发送了%d个字节！\n\n", ret);
}
FD_ZERO(&t_set1);
FD_SET(sockfd, &t_set1);
tv.tv_sec= 0;
tv.tv_usec= 0;
h= 0;
while(1){
sleep(2);
printf("--------------->1");
h = select(sockfd +1, &t_set1, NULL, NULL, &tv);
printf("--------------->2");
//if (h == 0) continue;
if (h == -1) {
close(sockfd);
printf("在读取数据报文时SELECT检测到异常，该异常导致线程终止！\n");
return -1;
};
if ( FD_ISSET(sockfd, &t_set1) ){
memset(buf, 0, 4096);
i= read(sockfd, buf, 4095);
if (i==0){
close(sockfd);
printf("读取数据报文时发现远端关闭，该线程终止！\n");
return -1;
}
printf("%s\n", buf);
}
}
close(sockfd);
return 0;
}
请求一个HTTP服务器的数据， 接收一个参数为请求的服务器IP：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>
int main(int argc, char *argv[]){
if(argc!=2){
printf("error usage %s ip\n",argv[0]);
return 1;
}
int sockfd;
int len;
struct sockaddr_in address;
int result;
char httpstring[100];
sprintf(httpstring,"GET / HTTP/1.1\r\n"
"Host: %s\r\n"
"Connection: Close\r\n\r\n",argv[1]);
char ch;
sockfd = socket(AF_INET, SOCK_STREAM, 0);
address.sin_family = AF_INET;
address.sin_addr.s_addr = inet_addr(argv[1]);
address.sin_port = htons(80);
len = sizeof(address);
result = connect(sockfd,(struct sockaddr *)&address,len);
if(result == -1){
perror("oops: client");
return 1;
}
write(sockfd,httpstring,strlen(httpstring));
while(read(sockfd,&ch,1)){
printf("%c", ch);
}
close(sockfd);
printf("\n");
return 0;
}
