HTTP是基于IP/TCP加上了网络请求的固定格式， 比如：

  1. method
  2. URL
  3. Content-host
  4. Content-Type
  5. 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：

  1. #include <stdio.h>
  2. #include <sys/socket.h>
  3. #include <sys/types.h>
  4. #include <time.h>
  5. #include <errno.h>
  6. #include <signal.h>
  7. #include <stdlib.h>
  8. #include <string.h>
  9. #include <unistd.h>
  10. #include <sys/wait.h>
  11. #include <sys/time.h>
  12. #include <netinet/in.h>
  13. #include <arpa/inet.h>
  15. #define IPSTR "42.121.252.58" //服务器IP地址;
  16. #define PORT 80
  17. #define BUFSIZE 1024
  19. int main(int argc, char **argv)
  20. {
  21.         int sockfd, ret, i, h;
  22.         struct sockaddr_in servaddr;
  23.         char str1[4096], str2[4096], buf[BUFSIZE], *str;
  24.         socklen_t len;
  25.         fd_set   t_set1;
  26.         struct timeval  tv;
  28.          //创建套接字
  29.         if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
  30.                 printf("创建网络连接失败,本线程即将终止---socket error!\n");
  31.                 exit(0);
  32.         };
  34.         bzero(&servaddr, sizeof(servaddr));
  35.         servaddr.sin_family = AF_INET;
  36.         servaddr.sin_port = htons(PORT);
  37.         if (inet_pton(AF_INET, IPSTR, &servaddr.sin_addr) <= 0 ){
  38.                 printf("创建网络连接失败,本线程即将终止--inet_pton error!\n");
  39.                 exit(0);
  40.         };
  42.         if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0){
  43.                 printf("连接到服务器失败,connect error!\n");
  44.                 exit(0);
  45.         }
  46.         printf("与远端建立了连接\n");
  47.         memset(str2, 0, 4096);
  48.         strcat(str2, "theDataToPost");
  49.         str=(char *)malloc(128);
  50.         len = strlen(str2);
  51.         sprintf(str, "%d", len);
  53.         memset(str1, 0, 4096);
  54.         strcat(str1, "GET /ymnets/p/6255674.html HTTP/1.1\n");
  55.         strcat(str1, "Host: www.cnblogs.com\n");
  56.         strcat(str1, "Content-Type: text/html\n");
  57.         strcat(str1, "Content-Length: ");
  58.         strcat(str1, str);
  59.         strcat(str1, "\n\n");
  61.         strcat(str1, str2);
  62.         strcat(str1, "\r\n\r\n");
  63.         printf("%s\n",str1);
  65.         ret = write(sockfd,str1,strlen(str1));
  66.         if (ret < 0) {
  67.                 printf("发送失败！错误代码是%d，错误信息是'%s'\n",errno, strerror(errno));
  68.                 exit(0);
  69.         }else{
  70.                 printf("消息发送成功，共发送了%d个字节！\n\n", ret);
  71.         }
  73.         FD_ZERO(&t_set1);
  74.         FD_SET(sockfd, &t_set1);
  76.         while(1){
  77.                 sleep(2);
  78.                 tv.tv_sec= 0;
  79.                 tv.tv_usec= 0;
  80.                 h= 0;
  81.                 printf("--------------->1");
  82.                 h= select(sockfd +1, &t_set1, NULL, NULL, &tv);
  83.                 printf("--------------->2");
  85.                 //if (h == 0) continue;
  86.                 if (h < 0) {
  87.                         close(sockfd);
  88.                         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");
  89.                         return -1;
  90.                 };
  92.                 if (h > 0){
  93.                         memset(buf, 0, 4096);
  94.                         i= read(sockfd, buf, 4095);
  95.                         if (i==0){
  96.                                 close(sockfd);
  97.                                 printf("读取数据报文时发现远端关闭，该线程终止！\n");
  98.                                 return -1;
  99.                         }
  101.                         printf("%s\n", buf);
  102.                 }
  103.         }
  104.         close(sockfd);
  107.         return 0;
  108. }

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：

  1. #include <stdio.h>
  2. #include <sys/socket.h>
  3. #include <sys/types.h>
  4. #include <time.h>
  5. #include <errno.h>
  6. #include <signal.h>
  7. #include <stdlib.h>
  8. #include <string.h>
  9. #include <unistd.h>
  10. #include <sys/wait.h>
  11. #include <sys/time.h>
  12. #include <netinet/in.h>
  13. #include <arpa/inet.h>
  15. #define IPSTR "61.147.124.120"
  16. #define PORT 80
  17. #define BUFSIZE 1024
  19. int main(int argc, char **argv)
  20. {
  21.         int sockfd, ret, i, h;
  22.         struct sockaddr_in servaddr;
  23.         char str1[4096], str2[4096], buf[BUFSIZE], *str;
  24.         socklen_t len;
  25.         fd_set   t_set1;
  26.         struct timeval  tv;
  28.         if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
  29.                 printf("创建网络连接失败,本线程即将终止---socket error!\n");
  30.                 exit(0);
  31.         };
  33.         bzero(&servaddr, sizeof(servaddr));
  34.         servaddr.sin_family = AF_INET;
  35.         servaddr.sin_port = htons(PORT);
  36.         if (inet_pton(AF_INET, IPSTR, &servaddr.sin_addr) <= 0 ){
  37.                 printf("创建网络连接失败,本线程即将终止--inet_pton error!\n");
  38.                 exit(0);
  39.         };
  41.         if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0){
  42.                 printf("连接到服务器失败,connect error!\n");
  43.                 exit(0);
  44.         }
  45.         printf("与远端建立了连接\n");
  47.         memset(str2, 0, 4096);
  48.         strcat(str2, "qqCode=287101329");
  49.         str=(char *)malloc(128);
  50.         len = strlen(str2);
  51.         sprintf(str, "%d", len);
  53.         memset(str1, 0, 4096);
  54.         strcat(str1, "POST /webservices/qqOnlineWebService.asmx/qqCheckOnline HTTP/1.1\n");
  55.         strcat(str1, "Host: www.webxml.com.cn\n");
  56.         strcat(str1, "Content-Type: application/x-www-form-urlencoded\n");
  57.         strcat(str1, "Content-Length: ");
  58.         strcat(str1, str);
  59.         strcat(str1, "\n\n");
  60.         //str2的值为post的数据
  61.         strcat(str1, str2);
  62.         strcat(str1, "\r\n\r\n");
  63.         printf("%s\n",str1);
  65.         ret = write(sockfd,str1,strlen(str1));
  66.         if (ret < 0) {
  67.                 printf("发送失败！错误代码是%d，错误信息是'%s'\n",errno, strerror(errno));
  68.                 exit(0);
  69.         }else{
  70.                 printf("消息发送成功，共发送了%d个字节！\n\n", ret);
  71.         }
  73.         FD_ZERO(&t_set1);
  74.         FD_SET(sockfd, &t_set1);
  76.         while(1){
  77.                 sleep(2);
  78.                 tv.tv_sec= 0;
  79.                 tv.tv_usec= 0;
  80.                 h= 0;
  81.                 printf("--------------->1");
  82.                 h= select(sockfd +1, &t_set1, NULL, NULL, &tv);
  83.                 printf("--------------->2");
  85.                 //if (h == 0) continue;
  86.                 if (h < 0) {
  87.                         close(sockfd);
  88.                         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");
  89.                         return -1;
  90.                 };
  92.                 if (h > 0){
  93.                         memset(buf, 0, 4096);
  94.                         i= read(sockfd, buf, 4095);
  95.                         if (i==0){
  96.                                 close(sockfd);
  97.                                 printf("读取数据报文时发现远端关闭，该线程终止！\n");
  98.                                 return -1;
  99.                         }
  101.                         printf("%s\n", buf);
  102.                 }
  103.         }
  104.         close(sockfd);
  107.         return 0;
  108. }

POST请求的方式可以再改改：

  1. #include <stdio.h>
  2. #include <sys/socket.h>
  3. #include <sys/types.h>
  4. #include <time.h>
  5. #include <errno.h>
  6. #include <signal.h>
  7. #include <stdlib.h>
  8. #include <string.h>
  9. #include <unistd.h>
  10. #include <sys/wait.h>
  11. #include <sys/time.h>
  12. #include <netinet/in.h>
  13. #include <arpa/inet.h>
  15. #define IPSTR "61.147.124.120"
  16. #define PORT 80
  17. #define BUFSIZE 1024
  19. int main(int argc, char **argv)
  20. {
  21.         int sockfd, ret, i, h;
  22.         struct sockaddr_in servaddr;
  23.         char str1[4096], str2[4096], buf[BUFSIZE], *str;
  24.         socklen_t len;
  25.         fd_set   t_set1;
  26.         struct timeval  tv;
  28.         if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
  29.                 printf("创建网络连接失败,本线程即将终止---socket error!\n");
  30.                 exit(0);
  31.         };
  33.         bzero(&servaddr, sizeof(servaddr));
  34.         servaddr.sin_family = AF_INET;
  35.         servaddr.sin_port = htons(PORT);
  36.         if (inet_pton(AF_INET, IPSTR, &servaddr.sin_addr) <= 0 ){
  37.                 printf("创建网络连接失败,本线程即将终止--inet_pton error!\n");
  38.                 exit(0);
  39.         };
  41.         if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0){
  42.                 printf("连接到服务器失败,connect error!\n");
  43.                 exit(0);
  44.         }
  45.         printf("与远端建立了连接\n");
  47.         memset(str2, 0, 4096);
  48.         strcat(str2, "qqCode=287101329");
  49.         str=(char *)malloc(128);
  50.         len = strlen(str2);
  51.         sprintf(str, "%d", len);
  53.         memset(str1, 0, 4096);
  54.         strcat(str1, "POST /webservices/qqOnlineWebService.asmx/qqCheckOnline HTTP/1.1\n");
  55.         strcat(str1, "Host: www.webxml.com.cn\n");
  56.         strcat(str1, "Content-Type: application/x-www-form-urlencoded\n");
  57.         strcat(str1, "Content-Length: ");
  58.         strcat(str1, str);
  59.         strcat(str1, "\n\n");
  60.         //str2的值为post的数据
  61.         strcat(str1, str2);
  62.         strcat(str1, "\r\n\r\n");
  63.         printf("%s\n",str1);
  65.         ret = write(sockfd,str1,strlen(str1));
  66.         if (ret < 0) {
  67.                 printf("发送失败！错误代码是%d，错误信息是'%s'\n",errno, strerror(errno));
  68.                 exit(0);
  69.         }else{
  70.                 printf("消息发送成功，共发送了%d个字节！\n\n", ret);
  71.         }
  73.         FD_ZERO(&t_set1);
  74.         FD_SET(sockfd, &t_set1);
  76.         tv.tv_sec= 0;
  77.         tv.tv_usec= 0;
  78.         h= 0;
  79.         while(1){
  80.                 sleep(2);
  81.                 printf("--------------->1");
  82.                 h = select(sockfd +1, &t_set1, NULL, NULL, &tv);
  83.                 printf("--------------->2");
  84.                 //if (h == 0) continue;
  85.                 if (h == -1) {
  86.                         close(sockfd);
  87.                         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");
  88.                         return -1;
  89.                 };
  90.                 if ( FD_ISSET(sockfd, &t_set1) ){
  91.                         memset(buf, 0, 4096);
  92.                         i= read(sockfd, buf, 4095);
  93.                         if (i==0){
  94.                                 close(sockfd);
  95.                                 printf("读取数据报文时发现远端关闭，该线程终止！\n");
  96.                                 return -1;
  97.                         }
  98.                         printf("%s\n", buf);
  99.                 }
  100.         }
  101.         close(sockfd);
  104.         return 0;
  105. }

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：

  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. #include <sys/types.h> 
  5. #include <sys/socket.h>
  6. #include <arpa/inet.h>
  7. #include <netinet/in.h>
  8. #include <unistd.h>
  9.  int main(int argc, char *argv[]){ 
  10.     if(argc!=2){
  11.       printf("error usage %s ip\n",argv[0]); 
  12.       return 1;
  13.     } 
  14.     int sockfd;
  15.     int len; 
  16.     struct sockaddr_in address; 
  17.     int result; 
  18.     char httpstring[100]; 
  19.     sprintf(httpstring,"GET / HTTP/1.1\r\n"
  20.           "Host: %s\r\n"
  21.           "Connection: Close\r\n\r\n",argv[1]); 
  22.     char ch; 
  23.     sockfd = socket(AF_INET, SOCK_STREAM, 0); 
  24.     address.sin_family = AF_INET; 
  25.     address.sin_addr.s_addr = inet_addr(argv[1]); 
  26.     address.sin_port = htons(80); 
  27.     len = sizeof(address);
  28.     result = connect(sockfd,(struct sockaddr *)&address,len); 
  29.     if(result == -1){ 
  30.        perror("oops: client"); 
  31.        return 1; 
  32.     }
  33.     write(sockfd,httpstring,strlen(httpstring)); 
  34.     while(read(sockfd,&ch,1)){ 
  35.       printf("%c", ch); 
  36.     } 
  37.     close(sockfd); 
  38.     printf("\n"); 
  39.     return 0; 
  40.  }