Hi all, yesterday I tried to enable PicoLisp for IPv6. In the end I gave it up, and decided to postpone the issue.
The problem is not IPv6 by itself, but the question how to support _both_ protocols for the next years. At first things looked good. Changing 'connect' was no problem. I used getaddrinfo() as recommended to get the list of visible servers (any protocol), and then iterated that list until an entry was found where socket() and connect() succeeded. So this works transparently for IPv4 and IPv6 servers, local and remote. Then 'udp' gave the first trouble. Again, getaddrinfo() returns a list of IPv4 and IPv6 addresses. But I found no way to determine which is the right one to use, as UDP gives no indication of success or failure. Calling socket() and sendto() succeeds, no matter whether the remote server supports IPv6 or not. Does anybody know what to do here? Finally, I didn't find a solution for the server side. This is the 'port' function, which takes a port number (or a range of numbers), and returns a socket descriptor (a number) bound to a port. This number can be used in functions like 'listen', 'accept' or 'udp'. Now it would be nice if there were a way to bind that socket in such a way that it accepts both IPv4 and IPv6 connections. In fact, this is even possible (using hybrid "mapped addresses"), but this is not recommended, because it does not work on some operating systems (e.g. OpenBSD), may impose security problems, and didn't work here on my Linux box anyway (it is also a matter of configuration, bug I didn't dig into that). The recommended way, using two sockets for each listening server is also not an option. For one thing, I don't want to use the double number of file descriptors. Second, it breaks the PicoLisp API where a socket is returned from 'port', and passed to 'listen' or other functions. This would break if more than one socket were involved. Clueless, - Alex -- UNSUBSCRIBE: mailto:picol...@software-lab.de?subject=unsubscribe
