No work, no work

dadadark

The company did IM, so I went in and asked me to write some small programs. The server listens and displays all characters sent by the client. The client may have 100,000 characters. Run under win.
The program is written in C ++ BUILDER. "Socket error" is reported when running.
code show as below.
I want to ask 2 questions:
1. Why does the socket fail?
2. In the for loop, I want to use multi-threaded processing, how to achieve it?

 #include <winsock2.h>
 #include <stdio.h>

 #define PORT 1234
 #define SERVER_IP "127.0.0.1"

int main (int argc, char * argv [])
{
    int sockfd, new_fd;
    struct sockaddr_in addr;
    

    if (INVALID_SOCKET == (sockfd = socket (AF_INET, SOCK_STREAM, 0)))
    {
       printf ("socket error\n");
       goto end;
    }

    memset (&addr, 0, sizeof (addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons (PORT);
    addr.sin_addr.s_addr = inet_addr (SERVER_IP);


    if (connect (sockfd, (const struct sockaddr FAR *)&addr, sizeof (addr)))
    {
       printf ("connect error\n");
       goto end;
    }

    if (listen (sockfd, SOMAXCONN))
    {
       printf ("listen error\n");
       goto end;
    }

    for (;;)
    {
       // how to deal with
    }

    end:
    system ("pause");
    return 0;
}

1231456

Windows platform needs to be initialized with WSAStartup
     #define sockstart (name)\
                do {\
                        WSADATA name;\
                        if (WSAStartup (MAKEWORD (1,1),&name))\
                                perror ("sockstart");\
                } while (0)

        #define sockend () WSACleanup ()

sockstart (wsad);

100,000 clients on one machine?

dadadark

Add the above code, the socket can be normal, but the connection fails again

The above code is server-side

鸟哥

Is socket used naked? Have you found a ready-made library or package

babymaya

There are many good design patterns for multithreading, such as thread pools, etc.

fan3786

I don't know anything, what should I do?

china1839

#include <winsock2.h>
 #include <stdio.h>

 #define PORT 1234
 #define SERVER_IP "127.0.0.1"

int main (int argc, char * argv [])
{
    int sockfd, new_fd;
    struct sockaddr_in addr;
    

    if (INVALID_SOCKET == (sockfd = socket (AF_INET, SOCK_STREAM, 0))) // This condition?
    {
       printf ("socket error\n");
       goto end;
    }

    memset (&addr, 0, sizeof (addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons (PORT);
    addr.sin_addr.s_addr = inet_addr (SERVER_IP);


    if (connect (sockfd, (const struct sockaddr FAR *)&addr, sizeof (addr)))
// The server first bind connect?
    {
       printf ("connect error\n");
       goto end;
    }

    if (listen (sockfd, SOMAXCONN))
    {
       printf ("listen error\n");
       goto end;
    }
// Create a thread for receiving and sending
    for (;;)
    {
       // how to deal with
    }

    end:
    system ("pause");
    return 0;
}

dadadark

Modify it and replace connect with bind, just fine.

The code now looks like this:

 void mythread (void * arg)
 {
      char buffer [MAX_LENGTH];
      int sockfd = * (SOCKET *) arg;
      recv (sockfd, buffer, MAX_LENGTH, 0);
      printf ("% s\n", buffer);
      _endthread ();
 }

main ()
{
   // do something

   for (;;)
    {
        new_fd = accept (sockfd, 0,0);
        if (INVALID_SOCKET! = new_fd)
        {
            _beginthread (mythread, 0,&new_fd);
        }
        else
        {
            printf ("wait\n");
        }
    } // end for
  
    closesocket (sockfd);
}

my question is
1. Do you want to close socksfd before beginthread
2. Right way to create a new thread
3. If it is not connected, the accept is called continuously, continuously outputting "wait", which consumes resources,
   How to block accept and wait until there is a connection.

micheal335

Learn. But what I write is blocking.

#include <stdio.h>
#include <stdlib.h>
#include <Winsock2.h>

void main ()
{
struct sockaddr_in test;
struct sockaddr_in re;
FILE * p = NULL;
SOCKET test1, test2;
int a, b;
WORD wVersion = MAKEWORD (2,0);
WSADATA wsData;

char buff [60];
int nResult = WSAStartup (wVersion,&wsData);

test.sin_port = 4000; // guaranteed byte order
test. sin_addr.s_addr = htonl (INADDR_ANY);
test.sin_family = AF_INET;
b = sizeof (struct sockaddr_in);
test1 = socket (AF_INET, SOCK_STREAM, 0);

if (test1 == INVALID_SOCKET)
{
exit (0);
}

a = bind (test1, (struct sockaddr *)&test, sizeof (struct sockaddr));
if (0! = a)
{
printf ("bind err\n");
exit (0);
}


a = listen (test1,1);

test2 = accept (test1, (struct sockaddr *)&re,&b);
if (test2! = INVALID_SOCKET)
{
printf ("connt\n");
}

p = fopen ("test.exe", "wb +");

while (1)
{
a = recv (test2,&buff [0], 50,0);
Ranch
if (0 == a)
{
a = WSAGetLastError ();
printf ("recv err\n");
exit (0);
} else
{
fwrite (buff, 50,1, p);
printf ("% s\n", buff);
}
}

a = send (test2,&buff [0], sizeof (buff), 0);

test2 = accept (test1, (struct sockaddr *)&re,&b);

}

food0012

Under Windows, you can try to complete the port, thread pool, etc.