In message <596196444196086313@unknownmsgid>, Matt Addison writes:
On Mar 1, 2012, at 17:10, William Herrin <bill@herrin.us> wrote:
If took you 50 lines of code to do 'socket=connect("www.google.com",80,TCP);' and you still managed to produce a version which, due to the timeout on dead addresses, is worthless for any kind of interactive program like a web browser. And because that code isn't found in a system library, every single application programmer has to write it all over again.
I'm a fan of Rube Goldberg machines but that was ridiculous.
I'm thinking for this to work it would have to be 2 separate calls:
Call 1 being to the resolver (using lwres, system resolver, or whatever you want to use) and returning an array of struct addrinfo- same as gai does currently. If applications need TTL/SRV/$NEWRR awareness it would be implemented here.
Call 2 would be a "happy eyeballs" connect syscall (mconnect? In the spirit of sendmmsg) which accepts an array of struct addrinfo and returns an fd. In the case of O_NONBLOCK it would return a dummy fd (as non-blocking connects do currently) then once one of the connections finishes handshake the kernel connects it to the FD and signals writable to trigger select/poll/epoll. This allows developers to keep using the same loops (and most of the APIs) they're already comfortable with, keeps DNS out of the kernel, but hopefully provides a better and easier to use connect() experience, for SOCK_STREAM at least.
It's not as neat as a single connect() accepting a name, but seems to be a happy medium and provides a standardized/predictable connect() experience without breaking existing APIs.
~Matt
And you can do the same in userland with kqueue and similar. int connectxx(struct addrinfo *res0, int *fd, int *timeout, void**state); 0 *fd is a connected socket. EINPROGRESS Wait on '*fd' with a timeout of 'timeout' nanoseconds. ETIMEDOUT connect failed. If timeout or state is NULL you block. You re-call with res0 set to NULL. -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@isc.org