Expected behavior of getsockname for unbound socket

[metamon123]

Hi. I wonder the expected behavior of syscall getsockname for unbound socket in KENS.

In the following references which are mentioned in PA#2 doc, there is no well-defined specification for unbound socket input.

• https://linux.die.net/man/2/getsockname
  • no specification for unbound socket
• https://linux.die.net/man/3/getsockname
  • If the socket has not been bound to a local name, the value stored in the object pointed to by address is unspecified.

Specifically, I wonder these three.

1. What should getsockname return for unbound socket input, considering future PA3 too? Success (0) vs Error (-1)
2. What should getsockname set on the given addr input for unbound socket input? Can it just skip setting addr?
3. If connection is established without user's bind call, should getsockname return the address that system (i.e. KENS) arbitrarily assigned?
   • ex. connect without bind / listen without bind (I'm not sure whether latter is legitimate or not)

[Pusnow]

1. What should getsockname return for unbound socket input, considering future PA3 too? Success (0) vs Error (-1)
2. What should getsockname set on the given addr input for unbound socket input? Can it just skip setting addr?

Unbound socket would return INADDR_ANY (0.0.0.0) and zero for return value, and the result will not used in the PA3.

3. If connection is established without user's bind call, should getsockname return the address that system (i.e. KENS) arbitrarily assigned?

For the connected sockets, an address in 5-tuple is returned.

If you're curious about the specific behavior of a system call, you can try it on a Linux machine.