Basic Winsock Problem.

Sebastiani · Aug 17, 2003

Hi, all. I am having a problem getting connect() to complete successfully. I've tried to isolate the problem a bit, and in the below example simply use the manifest constant INADDR_LOOPBACK for simplicity. Any help would be greatly appreciated!

Code:

#include <iostream>
#include <winsock.h>

int main()
{
 WSADATA wsa;

  if(WSAStartup(0x0101, &wsa)!=0)
   cout << &quot;!WSAStartup()&quot; << endl;

  else
 {
  SOCKET handle = socket(AF_INET, SOCK_STREAM, 0);

    if(handle == INVALID_SOCKET)
     cout << &quot;!socket()&quot; << endl;

    else
   {
    sockaddr_in addr;
    memset(&addr, 0, sizeof(sockaddr_in));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(80);
    addr.sin_addr.s_addr = INADDR_LOOPBACK;

       if(connect(handle, (sockaddr*)&addr, sizeof(sockaddr_in)) == SOCKET_ERROR)
        cout << &quot;!connect()&quot; << endl;

       else
      {
       cout << &quot;Yahoo!&quot; << endl;
      }

    shutdown(handle, SD_BOTH);
    closesocket(handle);
  }

  WSACleanup();
 }
 return cin.get();
}

Cagliostro · Aug 18, 2003

I think, this would help.
////////////server////////////////
#include<conio.h>
#include<io.h>
#include<stdlib.h>
#include<stdio.h>
#include<winsock2.h>
#include<windows.h>
//WS2_32.Lib required
#define PORTNUM 888;
//server
bool run = true;
DWORD WINAPI ThreadProcCln(void* xx)
{
int ns = *(int*)xx;
char buf[80];
while(1)
{
gets(buf);
send(ns, buf, sizeof(buf), 0);
if(strcmp("exit", buf) == 0)break;
}
run = false;
return 0;
}
DWORD WINAPI ThreadProcSvr(void* xx)
{
int ns = *(int*)xx;
char buf[80];
HANDLE hThreadCln = 0;
ULONG th_id;
while(1)
{
int nbytes = recv(ns, buf, sizeof(buf), 0);
if(!hThreadCln)hThreadCln = CreateThread(0, 0, ThreadProcCln, (void*)&ns, 0, &th_id);
if(!hThreadCln){printf("error on creating thread\n&quot

;exit(1);}
printf("%s\n", buf);
if(strcmp("exit", buf) == 0)break;
}
run = false;
return 0;
}
int main()
{
WORD wVersionRequested = MAKEWORD( 2, 2 );
WSADATA wsd;
WSAStartup(wVersionRequested, &wsd);
int s, ns;
int nport;
nport = PORTNUM;
nport = htons((u_short)nport);
sockaddr_in svr_addr, cln_addr;
s = socket(AF_INET, SOCK_STREAM, 0);
if((s = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET)
{
printf("error on calling socket()\n&quot

;
exit(1);
}
svr_addr.sin_family = AF_INET;
svr_addr.sin_addr.S_un.S_addr = (u_long)INADDR_ANY;
svr_addr.sin_port = nport;
if(bind(s, (const sockaddr*)&svr_addr, sizeof(svr_addr)) == -1)
{
printf("error on calling bind()&quot

;
exit(1);
}
printf("server ready: %s\n", inet_ntoa(svr_addr.sin_addr));
if(listen(s, 5) == -1)
{
printf("error on calling listen()\n&quot

;
exit(1);
}

while(1)
{
int addrlen;
addrlen = sizeof(cln_addr);
if((ns = accept(s, (sockaddr*)&cln_addr, &addrlen)) == -1)
{
printf("error on calling accept\n&quot

;
exit(1);
}
printf("client: %s\n", inet_ntoa(cln_addr.sin_addr));
int nbytes;
char buf[80];
ULONG th_id;
HANDLE hThreadSvr = 0;
hThreadSvr = CreateThread(0, 0, ThreadProcSvr, (void*)&ns, 0, &th_id);
if(!hThreadSvr){printf("error on creating thread&quot

;exit(1);}
while(run);
close(ns);
close(s);
exit(0);
}
return 0;
}
////////////server////////////////
////////////client////////////////
#include<io.h>
#include<stdio.h>
#include<stdlib.h>
#include<winsock2.h>
#include<windows.h>
#define PORTNUM 888
#include<windows.h>
bool run = true;
DWORD WINAPI ThreadProcToSvr(void* xx)
{
int ns = *(int*)xx;
char buf[80];
while(1)
{
int nbytes = recv(ns, buf, sizeof(buf), 0);
printf("%s\n", buf);
if(strcmp("exit", buf) == 0)break;
}
run = false;
return 0;
}
DWORD WINAPI ThreadProcCln(void* xx)
{
int ns = *(int*)xx;
char buf[80];
HANDLE hThreadCln = 0;
ULONG th_id;
while(1)
{
gets(buf);
send(ns, buf, sizeof(buf), 0);
if(!hThreadCln)hThreadCln = CreateThread(0, 0, ThreadProcToSvr, (void*)&ns, 0, &th_id);
if(!hThreadCln){printf("error on creating thread\n&quot

;exit(1);}
if(strcmp("exit", buf) == 0)break;
}
run = false;
return 0;
}

int main(HINSTANCE, HINSTANCE, LPSTR, int)
{
WORD wVersionRequested = MAKEWORD( 2, 2 );
WSADATA wsd;
WSAStartup(wVersionRequested, &wsd);

int s;//SOCKET

sockaddr_in svr_addr;//sei-filipski
hostent *hp;
char buf[80] = "salut la toti";
if((hp = gethostbyname("icurici&quot

) == 0)
{
printf("error on calling gethostbyname()\n&quot

;
exit(1);
}
strncpy((char*)&svr_addr.sin_addr.S_un.S_un_b, hp->h_addr_list[0], hp->h_length);

svr_addr.sin_family = hp->h_addrtype;
svr_addr.sin_port = htons((u_short)PORTNUM);
if((s = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
printf("error on creating socket\n&quot

;
exit(1);
}
if(connect(s, (const sockaddr*)&svr_addr, sizeof(svr_addr)) == -1)
{
printf("error on calling connect()\n&quot

;
exit(1);
}
ULONG th_id;
HANDLE hThreadSvr = 0;
hThreadSvr = CreateThread(0, 0, ThreadProcCln, (void*)&s, 0, &th_id);
if(!hThreadSvr){printf("error on creating thread&quot

;exit(1);}
while(run);
close(s);
return 0;
}
////////////client////////////////

Ion Filipski

ICQ: 95034075
AIM: IonFilipski
filipski@excite.com

Sebastiani · Aug 18, 2003

Thanks for the reply. Unfortunately, it still fails to connect, though I don't know why. The most frustrating thing is that I did this a year or so ago without any problems. :-/

And yes, in the actual program I was using something like:

Code:

hostent * host = gethostbyname(&quot;[URL unfurl="true"]www.google.com&quot;);[/URL]

if(!host) 
 cout << &quot;!gethostbyname()&quot; << endl;
else
{ 
 memcpy(&addr.sin_addr.s_addr, host->h_addr_list[0], sizeof(unsigned long));  
}

Still, no go. Any ideas?

Sebastiani · Aug 18, 2003

O.K. got it. Thanks for the suggestions.

Cagliostro · Aug 18, 2003

memcpy(&addr.sin_addr.s_addr, host->h_addr_list[0], sizeof(addr.sin_addr.s_addr));

Ion Filipski

ICQ: 95034075
AIM: IonFilipski
filipski@excite.com

Sebastiani · Aug 18, 2003

>> IonFilipski

Actually, the two are identical since S_addr is an unsigned long...

Take a look:

struct in_addr {
union {
struct { u_char s_b1,s_b2,s_b3,s_b4; } S_un_b;
struct { u_short s_w1,s_w2; } S_un_w;
u_long S_addr; <<
} S_un;

But after looking at my code, I saw what I had inadvertantly done:

address = (unsigned long)host->h_addr_list[0];

In other words, I had cast the first element of
h_addr_list[0] to an unsigned long instead of copying a sizeof(unsigned long) amount of bytes from the array.

Anyway, here is the function that I am using now. First it tries to resolve a dotted-decimal string to an address. If that fails, it assumes a hostname was provided.

Code:

unsigned long ip(const char * addr)
{
 unsigned long address = inet_addr(addr);

  if(address == INADDR_NONE)
 {
  hostent * host = gethostbyname(addr);

   if(host)
  {
   memcpy(&address, host->h_addr_list[0], sizeof(unsigned long));
  }
 }
 return address;
}

As to why my connection to INADDR_LOOPBACK failed was simple. I wasn't running a server on my machine to accept it! Major brain-fart there.

Thanks for all of the input guys...

Cagliostro · Aug 19, 2003

It does not matter. You must put the correct type of data, even you could put someshing else.

Ion Filipski

ICQ: 95034075
AIM: IonFilipski
filipski@excite.com

Sebastiani · Aug 19, 2003

No, you're still off.

The struct member S_addr is an unsigned long. It makes no difference.

Look:

struct foo {
unsigned long var;
};

foo bar;

int sz = sizeof(bar.var);

or...

int sz = sizeof(unsigned long);

Do you see why?

Cagliostro · Aug 20, 2003

is a S_addr, not a long. You can use S_addr for mathematical operation or learn to count, but for that is long, not socket address. It does not matter what originally socket address was a long.

Ion Filipski

ICQ: 95034075
AIM: IonFilipski
filipski@excite.com

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Basic Winsock Problem.

Sebastiani

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Cagliostro

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Sebastiani

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Sebastiani

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Cagliostro

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Sebastiani

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Cagliostro

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Sebastiani

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Cagliostro

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