C语言实现HTTP的GET和POST请求

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; 
 }

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