Socket: bind error...why??

[M.Caggiano]

Hi!
This code wants to simulate a possible answer of a server, to an
application of connection aside a client.
The server has to accept the connection and send a message with its
name.
The all through socket.

The program DOESN'T HAVE errors or warnings.

I have a problem in the function "bind" (what I have underlined with
of the "- ") because its return value is "-1" (therefore error!).
I don't understand because the function return this value.

Can you help me?
Thank's for all.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock.h>
#include <windows.h>

void err_fatal(char *);

main()
{
/* apertura connessione lato client */
int taddr_n, tport_n;
struct sockaddr_in saddr, caddr;
char *buffer;
int result=0,addrlen=0;
SOCKET s,s1;
WSADATA data; // inizializzo la variabile che contiene le primitive
di Winsock
WORD p;
int err=0;
p=MAKEWORD(2,0); // creo la variabile p che contiene la versione
della wsock32.dll
err=WSAStartup(p,&data); // inizializzo la wsock32.dll verificandone
la mancanza di errori

/* creazione socket */
s=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
if(s==INVALID_SOCKET) err_fatal("socket() failed!");

tport_n=htons(1037);
printf("\nhtons eseguita correttamente(%d)\n",tport_n);

saddr.sin_family=AF_INET;
saddr.sin_port=tport_n;
saddr.sin_addr.s_addr=INADDR_ANY; /* accetto qualsiasi indirizzo
*/

//----------------------------------------------------------------------------------------------------------------------
result=bind(s,(struct sockaddr *) &saddr, sizeof(saddr));
//----------------------------------------------------------------------------------------------------------------------
if(result==-1) err_fatal("Bind() fault");
buffer="My server name is: MIKY";
printf("%s",buffer);
result=listen(s,20);

/* accetto la connessione*/
addrlen=sizeof(struct sockaddr_in);
s1=accept(s,(struct sockaddr *) &caddr, &addrlen);

send(s1,buffer,strlen(buffer),0);

system("pause");

/* Chiude i socket */
WSACleanup();
closesocket(s);
}


/* stampa errore */
void err_fatal(char *mes)
{
printf("%s, errno=%d\n",mes,WSAGetLastError());
perror("");
system("pause");
exit(1);
}

 

[Walter Roberson]

This code wants to simulate a possible answer of a server, to an
application of connection aside a client.

I have a problem in the function "bind" (what I have underlined with
of the "- ") because its return value is "-1" (therefore error!).
I don't understand because the function return this value.

Can you help me?

bind() is not part of the standard C library. As you appear to
be using Windows, you should be asking in a Windows programming
newsgroup.

WSADATA data; // inizializzo la variabile che contiene le primitive
di Winsock

err=WSAStartup(p,&data); // inizializzo la wsock32.dll verificandone
la mancanza di errori

You are possibly using the value of data before it is initialized,
unless WSAStartup (whatever that is) happens to be storing a value
in through the pointer that you are providing to it.

tport_n=htons(1037);

result=bind(s,(struct sockaddr *) &saddr, sizeof(saddr));

What will happen if the port is already in use?

buffer="My server name is: MIKY";
printf("%s",buffer);

You do not appear to be flushing the buffer, and you are not
ending your buffers with \n . Possibly whatever you print is not
being sent until something later flushes the buffer, such as the
termination of the program. Consider using fflush(stdout).

void err_fatal(char *mes)
{
printf("%s, errno=%d\n",mes,WSAGetLastError());
perror("");

With your placement of perror() before the printf(), the
perror() could be reflecting an error result found in the
printf() routine rather than whatever error triggered you
calling err_fatal().

 

[M.Caggiano]

bind() is not part of the standard C library. As you appear to
be using Windows, you should be asking in a Windows programming
newsgroup.


You are possibly using the value of data before it is initialized,
unless WSAStartup (whatever that is) happens to be storing a value
in through the pointer that you are providing to it.


What will happen if the port is already in use?


You do not appear to be flushing the buffer, and you are not
ending your buffers with \n . Possibly whatever you print is not
being sent until something later flushes the buffer, such as the
termination of the program. Consider using fflush(stdout).


With your placement of perror() before the printf(), the
perror() could be reflecting an error result found in the
printf() routine rather than whatever error triggered you
calling err_fatal().

Thank's so much for the printf().

however i've resolved the problem of the "bind()".
All it took is changing number of port.
Thank's so much!!!