failed to bind socket

[kool]

Hi,

I got a problem with my UDP server on linux. On windows everything's fine, and it's suposed to be the same on linux.

The problem is on this line bind(sckHandle, (struct sockaddr*)(SvrAddress), sizeof(sockaddr_in))

except that this line is ok. I found on a forum a problem similar and the dude answered that it was solved, it was a problem with his firewall settings on linux.

I searched to modify them with FireStarter but could not find where was the problem.

I hope you guys can help me, thanks in advance.

[kbw]

What is the declaration for SvrAddress?

[kool]

sockaddr_in* SvrAddress;

and i initialized it with

SvrAddress = new sockaddr_in;

SvrAddress->sin_family = AF_INET;
SvrAddress->sin_addr.s_addr = htonl(ip);
SvrAddress->sin_port htons(port);

[jsmith]

What error are you getting? (errno)

[kool]

the result from bind is -1, if it's what u'r asking for.

[jsmith]

No, I'm asking for the value of errno.

[kool]

Well i don't know 'cause i didn't manage to find how it works, but i found the error str "Address Already In Use" But who would use the port 7153 and the IP address is equivalent to INADDR_ANY

[jsmith]

netstat -ap | grep 7153

will tell you which process.

Are you, by any chance opening two sockets and attempting to bind both to the same port?

[Galik]

It may be that the port is being held from a previous run of your program. Sometimes it takes time for it to be released. Don't know why.

[jsmith]

Machine A does that because it wants to give the other side (machine B) time to realize that machine A is
no longer responding and close its side of the connection. Otherwise, if a different process starts on Machine A
and opens the same port, it will receive packets that it can't comprehend.

To turn off this behavior, you have to set the SO_REUSEADDR socket option.

[kool]

Thanks for your precious help.

1. It was from a previous process wrong terminated. I guess CodeLite don't terminate the process it started when it crashes.

2. it is possible to check at Application startup if another process of the same name is open ?

[Galik]

Learn something new every day :o)

[jsmith]

You have a couple of options.

One is to create a temporary file with a well-known name somewhere (say /tmp) at the beginning of your program.
If it fails to create the file because it already exists, then you know another instance is running.

Another is to create a well-known semaphore at the beginning of your program. If it fails to create the semaphore
because it already exists, then you know another instance is running.