Problem using sockets

[Vlad Dogaru]

Hello,

I am trying to write a simple program to teach myself sockets. The
following bit of code fails with:
"connect: Socket operation on non-socket". What am I missing?

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <strings.h>
#include <sys/select.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>

int main(int argc, char **argv)
{
int s1, s2; /* socket descriptors */
extern int errno;
struct sockaddr_in sa1, sa2;
char aux[MAX_STR_LEN];
struct hostent *hp;

if (argc != 5) {
printf("Usage: %s <host1<port1<host2<port2>\n", argv[0]);
return 0;
}

if ((hp=gethostbyname(argv[1])) == 0) {
perror("gethostbyname");
return errno;
}

bzero(&sa1, sizeof sa1);
sa1.sin_family = AF_INET;
sa1.sin_port = htons(atoi(argv[2]));
sa1.sin_addr.s_addr = ((struct in_addr *)(hp->h_addr))->s_addr;

if ((s1=socket(AF_INET, SOCK_STREAM, 0) == -1)) {
perror("socket");
return errno;
}

if (connect(s1, (void *) &sa1, sizeof (sa1)) == -1) {
perror("connect");
return errno;
}
printf("Socket 1 connected");

Also, having two sockets open, can I use select() to read from them?
Can someone please point me to an example of using select() with
sockets?

Thanks in advance,
Vlad

[Keith Thompson]

"Vlad Dogaru" <dd****@gmail.comwrites:

I am trying to write a simple program to teach myself sockets.

[...]

Standard C does not include support for sockets.
Try comp.unix.programmer.

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Dave Thompson]

On 14 Jan 2007 01:50:30 -0800, "Vlad Dogaru" <dd****@gmail.comwrote:

Hello,

I am trying to write a simple program to teach myself sockets. The
following bit of code fails with:
"connect: Socket operation on non-socket". What am I missing?

The sockets part is offtopic but your problem is actually a C problem.

if ((s1=socket(AF_INET, SOCK_STREAM, 0) == -1)) {

This compares the return value from socket(...) to -1 to choose
whether to assign 0 or possibly 1 to s1. Neither of those is a valid
sd (in your obviously Unixoid environment) and even if valid wouldn't
be correct i.e. the value you want later. You need to move one of
your parentheses: if ( (s1=socket(...)) == -1 ) { error }

- David.Thompson1 at worldnet.att.net