Em Tue, May 13, 2008 at 09:59:35AM -0700, David Stevens escreveu: > Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote on 05/13/2008 09:23:25 > AM: > > > Em Tue, May 13, 2008 at 08:50:59AM -0700, David Stevens escreveu: > > > Are they mutually exclusive? > > > > > > Why not add SOCK_DGRAM/IPPROTO_DCCP support while leaving > > > > Because DCCP is not SOCK_DGRAM at all? :) > > Well, SOCK_STREAM/IPPROTO_DCCP then. :-) But it isn't really that > either, as Remi said. > If you do a connect() on a UDP socket, it doesn't cease to > be a SOCK_DGRAM socket, so I don't really care about that distinction, > but if others do, that's ok with me. There are ACKs here, too, so maybe. A "connection" on a UDP socket is not performed as a reliable handshake, its just simple "hey kernel, everytime I do a write please send to this default destination, would you do it for me?", whereas a connection on a DCCP socket is much like the same as a TCP connection. In Linux they share most of the connection establishment, minisocks, timewait sockets infrastructure even. So for connection purposes, DCCP is SOCK_STREAM, but when data is to be transmitted it really is a SOCK_DGRAM, i.e. it is neither :) > My point was really that, though not as pretty, the world won't > end if there are two ways to get to the same kind of socket, and > especially if adding a new one makes getaddrinfo() easier to deal with. > If the best way isn't the existing way, we could add it, and keep the > old way for backward compatibility only. > A "0" protocol had better continue to be TCP and UDP, and > specifying IPPROTO_DCCP makes it clear what the user wants, regardless As it makes specifying a SOCK_DCCP on a patched glibc :) If someone comes with a better name than SOCK_DCCP and keep the value already allocated, the better, SOCK_DCCP looks too much specific to one protocol, but it is just that there is only one specification for a reliable connection + unreliable data transfer protocol (that I know of). > of the type. So "just working" (even with any of SOCK_DGRAM, SOCK_STREAM, > and SOCK_DCCP) seems perfectly reasonable to me. My $.02. > A wrapper sound ok to me too. I think that the wrapper for older libcs + patching libc to know about this new kind of socket is the way to go. - Arnaldo -- To unsubscribe from this list: send the line "unsubscribe dccp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
