C automatically assigns a port

Question

I just wanted to know how to use C to automatically assign a free port (and see what was used) if a specific port number is not provided.

For example, I use this:

struct sockaddr_in address;
address->sin_family = AF_INET;
address->sin_addr.s_addr = INADDR_ANY;
address->sin_port = htons( port );

But how can I replace the sin_port assignment and let C automatically assign for me?

Thanks!

+2

Gary May 19 '10 at 3:33 am

2 answers

Just use the value 0

.

address->sin_port = 0

Alternatively, you can skip the binding step entirely if you don't like which interface you are using.

+3

Matt B. May 19 '10 at 3:37 am

Jujjuru · Accepted Answer · 2010-05-19T03:54:33+0000

Matt has already answered the question "how to assign a free port" (use sin_port = 0).

To answer the second part, which is "how to see what was used", use getsockname ()