On Thu, Aug 6, 2020 at 10:02 AM Uli Kunitz <uli.kun...@gmail.com> wrote:
> Reading is possible with IP_RECVTOS on Linux but requires the use of > recvmsg, because the TOS field is provided as ancillary data. This wouldn't > be very portable though. Raw sockets with IP_HDRINCL are a better option if > portability is a concern. Keep in mind that raw sockets are privileged under Linux. (the process must have CAP_NET_RAW either by being root, or some other mechanism) That vastly limits the usefulness of a QUIC implementation. > > On Wednesday, August 5, 2020 at 11:33:41 PM UTC+2 ma...@acln.ro wrote: > >> ECN bits are represented in the TOS field. I think you can use setsockopt >> with the IP_TOS option to set the TOS field on a socket. See ip(7). On the >> Go side, use the SyscallConn method on your UDPConn, then call setsockopt >> using the Control method. Something like this (untested): >> https://play.golang.org/p/6_R-zlBSibv >> >> On Wed, Aug 5, 2020 at 9:30 PM <marten...@gmail.com> wrote: >> >>> I'm working on a Go implementation of the QUIC protocol ( >>> https://github.com/lucas-clemente/quic-go). QUIC specifies how to use >>> ECN (Explicit Congestion Notification) to detect and respond to congestion >>> in the network (see >>> https://tools.ietf.org/html/draft-ietf-quic-transport-29#section-13.4 for >>> details on that). >>> >>> As far as I can see, there's no way to read (and write) the ECN bits >>> from the IP header, unless I use a raw socket, which would be a suboptimal >>> solution for many reasons. >>> The closest I could get to extracting information from the IP header was >>> by using *UDPConn.ReadFromUDP* and then using *golang.org/x/net/ipv4 >>> <http://golang.org/x/net/ipv4>* to parse the *oob* bytes into an >>> *ipv4.ControlMessage* (or equivalently for IPv6). This at least gives >>> me access to the TTL field. It seems like this approach is insufficient to >>> get access to the ECN bits though. >>> >>> Can anyone help me with this? >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "golang-nuts" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to golang-nuts...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/golang-nuts/3c96ecc4-e507-48d1-a912-9e3caf6ecd11o%40googlegroups.com >>> <https://groups.google.com/d/msgid/golang-nuts/3c96ecc4-e507-48d1-a912-9e3caf6ecd11o%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> >> -- >> Andrei Călin >> > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/fe7cd943-cbb2-4530-a71a-d0b72100fb67n%40googlegroups.com > <https://groups.google.com/d/msgid/golang-nuts/fe7cd943-cbb2-4530-a71a-d0b72100fb67n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CANrC0BhU3hRRAw4ghAh-4zs18tW-pBfqMZ69f-xiNFHUHFaZZw%40mail.gmail.com.
