Re: correct IP# for NFS kernel upcall to userland daemon
Rick Macklem wrote in : rm> In this case, I am concerned that the daemon will not be able to start up under rm> conditions where the DNS service isn't yet functional. (This problem can mostly rm> be avoided by specifying "localhost" in /etc/hosts and configuring the system to rm> use that file before DNS, but I still don't like having this dependency on DNS for rm> the daemon starting up.) rm> Note that the upcall will work for any IP# that refers to the local machine and it rm> does not need to be the one specified for "localhost" in the DNS. rm> rm> So, do you think I should do a lookup for "localhost" at daemon startup or use rm> a hardwired "127.0.0.1/::1"? I do not think using INADDR_LOOPBACK or IN6ADDR_LOOPBACK_INIT is harmful for this purpose. A properly configured lo0 should be a reasonable assumption. However, I still think using a loopback address in AF_INET or AF_INET6 for local communication is not a good idea when AF_LOCAL works. A properly configured file system is easier than lo0 in many cases. An unnamed pair of connected sockets which can be created by socketpair(2) would be ideal for this purpose, but IIRC there is no handy way to send one across kernel and userland... -- Hiroki pgpcAaAl_UC1B.pgp Description: PGP signature
Re: correct IP# for NFS kernel upcall to userland daemon
> Hi, > > I have been in a recent discussion about what the correct IP address to use > for > an upcall from the kernel to the NFS daemon nfsuserd (which maps between > uids<->usernames and gids<->group names). > > The code uses UDP for the upcall (I once committed a patch changing that to > an AF_LOCAL socket, but it broke certain sites where the directory the socket > was being created in was NFS mounted). > > Currently the code uses a hardwired "127.0.0.1". > Rodney Grimes feels that it would be better to do a name lookup on "localhost" > to get the address to use. > > In this case, I am concerned that the daemon will not be able to start up > under > conditions where the DNS service isn't yet functional. (This problem can > mostly > be avoided by specifying "localhost" in /etc/hosts and configuring the system > to > use that file before DNS, but I still don't like having this dependency on > DNS for > the daemon starting up.) > Note that the upcall will work for any IP# that refers to the local machine > and it > does not need to be the one specified for "localhost" in the DNS. > > So, do you think I should do a lookup for "localhost" at daemon startup or use > a hardwired "127.0.0.1/::1"? > > Thanks in advance for any comments, rick Note that my main issue with this is hardcoding of a value in the kernel that can not be changed, thus if I either have no lo0 or have configured lo0 to be something other than 127.0.0.1 this hard coded use by the kernel of 127.0.0.1 would fail and there would be no way around it short of a recompile. I see a few other hard coded localhost values in the kernel and minimally these should be garbage collected into #define LOCALHOST 0x7f01 and much beter would be to put these into a tunable, and finally best of all would be to find ways to not be depending on "optional lo0 && lo0 == 7f01" in the kernel or userland code. I do believe that the some of the test software used for CI is also having similiar issues, and suspect that hard coding these values in places is eventually going to lead to testability issues. -- Rod Grimes rgri...@freebsd.org ___ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
correct IP# for NFS kernel upcall to userland daemon
Hi, I have been in a recent discussion about what the correct IP address to use for an upcall from the kernel to the NFS daemon nfsuserd (which maps between uids<->usernames and gids<->group names). The code uses UDP for the upcall (I once committed a patch changing that to an AF_LOCAL socket, but it broke certain sites where the directory the socket was being created in was NFS mounted). Currently the code uses a hardwired "127.0.0.1". Rodney Grimes feels that it would be better to do a name lookup on "localhost" to get the address to use. In this case, I am concerned that the daemon will not be able to start up under conditions where the DNS service isn't yet functional. (This problem can mostly be avoided by specifying "localhost" in /etc/hosts and configuring the system to use that file before DNS, but I still don't like having this dependency on DNS for the daemon starting up.) Note that the upcall will work for any IP# that refers to the local machine and it does not need to be the one specified for "localhost" in the DNS. So, do you think I should do a lookup for "localhost" at daemon startup or use a hardwired "127.0.0.1/::1"? Thanks in advance for any comments, rick ___ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
