Send HTTP GET and non-blocking connect

Author: WhoAmI
email: [e-mail]

Date: 20230517
Copyright: CC BY-NC-SA

思考 如何 改成 n 個 連線, 選一最快回應的?

POST 在 message-body 中傳送
GET 在 HTTP Request 中

/*

Simple send http header
non-blocking connect

Author: WhoAmI
DATE:   20230517



You may need getaddrinfo (Linux man 3), please STUDY DNS and the following four files



/etc/host.conf
resolver configuration file
/etc/hosts
host database file
/etc/nsswitch.conf
name service switch configuration

/etc/gai.conf (configuration file)



*/


#include <stdio.h>
#include <sys/types.h>          /* See NOTES */
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/ip.h> /* superset of previous */
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

#include <signal.h>
#include <arpa/inet.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <netinet/in.h>
//errno
#include <errno.h>

#define debugerr(x) x

#define TRY 20
#define debugx(x) x

/*

HTTP client


GET /index.html?ip=1234567&name=jone HTTP/1.1
Host: 127.0.0.1:9999
*/

int getaddr(char *url, char *ipstr4, char *ipstr6)
{
   struct addrinfo hints, *res, *p;
    int status;
    char ipstr[INET6_ADDRSTRLEN];
    int count=0;

   
    memset(&hints, 0, sizeof hints);
   //  = AF_UNSPEC; // AF_INET or AF_INET6 to force version
    hints.ai_family=AF_INET ; //IPv4
    hints.ai_socktype = SOCK_STREAM;

    if ((status = getaddrinfo(url, NULL, &hints, &res)) != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(status));
        return 0;
    }

    debugx(printf("IP addresses for %s:\n\n", url));

    for(p = res;p != NULL; p = p->ai_next) {
        void *addr;
        char *ipver;

        // get the pointer to the address itself,
        // different fields in IPv4 and IPv6:
        if (p->ai_family == AF_INET) { // IPv4
            struct sockaddr_in *ipv4 = (struct sockaddr_in *)p->ai_addr;
            addr = &(ipv4->sin_addr);
            ipver = "IPv4";
            inet_ntop(p->ai_family, addr, ipstr4, sizeof ipstr);
            count++;
        } else { // IPv6
            struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)p->ai_addr;
            addr = &(ipv6->sin6_addr);
            ipver = "IPv6";
            if(ipstr6)inet_ntop(p->ai_family, addr, ipstr6, sizeof ipstr);
            debugx(printf("  %s: %s\n", ipver, ipstr));
        }

        
        //inet_ntop(p->ai_family, addr, ipstr, sizeof ipstr);
        
    }

    freeaddrinfo(res); // free the linked list

    return count;
}


int setnonblock (int fd) {

  int flags;
  int n;

  flags = fcntl(fd, F_GETFL);
//O_NONBLOCK=0x4000
  fcntl(fd, F_SETFL, flags | O_NONBLOCK);
  n= fcntl(fd, F_GETFL) & O_NONBLOCK;
  return n;
}
int setblock (int fd) {

  int flags;
  int n;

  flags = fcntl(fd, F_GETFL);
  fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);

  n= fcntl(fd, F_GETFL) & O_NONBLOCK;

  return n;
}



int connecttcp(char *ip,int port,int msecs){


//EAGAIN,
//EINTR:The system call was interrupted by a signal that was caught;

 int sockfd;
 struct sockaddr_in server_addr;
 socklen_t addrlen;
 int ret;
 int n;
 fd_set rfds,wfds;
 struct timeval tv;
 //int msecs=1000;
 int retval;
 int ok=0;
 int tryconnect=0;





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


 setnonblock(sockfd);

 memset(&server_addr,0, sizeof(server_addr));
 server_addr.sin_family = AF_INET;
 server_addr.sin_port = htons(port);
 server_addr.sin_addr.s_addr = inet_addr(ip);

 addrlen=sizeof(server_addr);

 n=1;

 do{
 

   FD_ZERO(&wfds);

   FD_SET(sockfd, &wfds);

   tv.tv_sec = msecs/1000;
   tv.tv_usec =(tv.tv_sec*1000-msecs)*1000;

   retval = select(sockfd+1,NULL,&wfds, NULL, &tv);//for writing
   tryconnect++;
   //printf("retval=%d",retval);
   errno=0;
   ret=connect(sockfd, (struct sockaddr *)&server_addr,addrlen);
   if(ret<0){
     //sleep(1);
     perror("connect");
     debugerr(fprintf(stderr,"errno=%d, EINPROGRESS=%d,EISCONN=%d\n",errno,EINPROGRESS,EISCONN));

    //connect: Operation now in progress
    //retval=1errno=119, 119


     //EINPROGRESS
     //EISCONN =127
     //Need select

     if(errno == EISCONN){
        ok=!0;
        break;
     }
     if (errno == EINTR){
                continue;
     }

     if (errno == EAGAIN ||errno==EINPROGRESS){
                continue;
     }
      if (errno == ECONNREFUSED){
                ok=0;
                break;
      }
   }else {
      ok=!0;
      break;
   }
   
   
   if(tryconnect >TRY){
       ok=0;
       break;
   }
 }while(n>0);

 if(ok){
    setblock(sockfd);

    debugerr(fprintf(stderr,"Connect to %s port %d, fd=%d\n",ip,port,sockfd));
    return  sockfd;  
 }   

 close(sockfd);
 debugerr(fprintf(stderr,"Cannot connect to %s port %d! close fd=%d \n",ip,port,sockfd));
 
 return 0;


}


int main(int argc,char *argv[])
{
   int fd;
   //char buf[128]="GET /demox.html?ip=31.31.520.99&name=Sugar31 HTTP/1.1\r\nHost: 127.0.0.1:9999\r\n\r\n\r\n";
   char buf[128]="GET /index.html?ip=31.31.520.99&name=Sugar31 HTTP/1.1\r\nHost: 127.0.0.1:9999\r\n\r\n\r\n";
   
   
   char ret[1204];
   int n;
   char ipv4[INET6_ADDRSTRLEN];
   char *ip="127.0.0.1";
   int port=80;

   int msec=1000;

   if(argc<2){
       printf("usage: %s hostname \n",argv[0]);
       exit(EXIT_FAILURE );
   }   
   printf("%s %s\n",argv[0],argv[1]);
   getaddr(argv[1],ipv4,NULL);
   
   printf("Connect to %s:%d [msec:%d] and\nSend:\n%s\n",ipv4,port,msec,buf);

   fd=connecttcp(ipv4,port,msec);

  // setnonblock(fd);
  //setblock(fd);

   if(fd>0){
 
   

      write(fd,buf,strlen(buf));
      do{
       memset(ret,0,sizeof(ret));
       n=read(fd,ret,sizeof(ret)-1);
       if(n>0){
          ret[n]=0;
          printf("--->%s\n",ret);


       }else break;
       
      }while(n>0);

      printf("close connection\n");
      //sleep(10);
   
      close(fd);


      exit(EXIT_SUCCESS);
   }
   exit(EXIT_FAILURE );

}