CODEWITHSUNDEEP
csocketsunixnetwork-programming
Mdp11
Mdp11

Reputation: 572

Creating and connecting a socket indipendently from the IP version using sockaddr_storage

I'm writing a client that can connect both to an IPv4 and an IPv6 address, making the code as generale as possible. I used the getaddrinfofunction to which I pass the string of the IP address, and from that I obtain the address family (at this point I know if it's IPv4 or IPv6). Now I need to bind that address and the port to a sockaddr structure. I've read that in order to make it general I should use sockaddr_storage and then using it by casting it to sockaddr, but I don't understand how to fill sockaddr_storage with the address and the port needed for the connection.

Thanks for your attention.

NB. I want it to work on UNIX.

Upvotes: 1

Views: 139

Answers (1)

Some programmer dude
Some programmer dude

Reputation: 409442

The POSIX specification only says that the sockaddr_storage should be

  • Large enough to accommodate all supported protocol-specific address structures

  • Aligned at an appropriate boundary so that pointers to it can be cast as pointers to protocol-specific address structures and used to access the fields of those structures without alignment problems

And

The sockaddr_storage structure shall contain at least the following members:

sa_family_t ss_family

There's some notes saying that the family structure member for all sockaddr-family structures will be at the same place, but that's about it.

So the I would say that the "best" way to use it is to have special cases for IPv4 and IPv6 that fills in the correct sockaddr_in or sockaddr_in6 structures, then memcpy them into a sockaddr_storage structure that can later be used.

Upvotes: 1

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