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>>>>> Jakub Jelinek writes: > Hi! > This seems to work for me on 2.2 (and I tried a short test which did all the > syscalls gethostbyname is doing when trying to talk to portmap which is not > running on 2.4). > Maybe I've put too many tests in there, the msg.msg_namelen == 0 test is > there because of bug in 2.2 as pointed out by Andi Kleen, ret can be 0 e.g > if some router on the way sends host unreacheable. If I get payload back, I > compare it to what we just sent to make sure it was ICMP for the same > message. > I'll try that glibc on 2.4 tomorrow. > The problem this patch solves can be reproduced e.g. by making sure nis is > before dns in nsswitch.conf and doing > domainname xyz.foo.com > killall portmap > then on 2.4 any hostname lookup will take eons. > 2001-01-09 Jakub Jelinek <jakub@redhat.com> > * sunrpc/clnt_udp.c (clntudp_bufcreate): Set IP_RECVERR on the > UDP socket. > (clntudp_call): Handle MSG_ERRQUEUE. > * sysdeps/generic/bits/errqueue.h: New. > * sysdeps/unix/sysv/linux/bits/errqueue.h: New. > --- libc/sunrpc/clnt_udp.c.jj Tue Aug 3 19:20:26 1999 > +++ libc/sunrpc/clnt_udp.c Tue Jan 9 18:51:32 2001 > @@ -51,6 +51,11 @@ static char sccsid[] = "@(#)clnt_udp.c 1 > #include <rpc/pmap_clnt.h> > #include <net/if.h> > +#ifdef IP_RECVERR > +#include <bits/errqueue.h> > +#include <sys/uio.h> > +#endif > + > extern bool_t xdr_opaque_auth (XDR *, struct opaque_auth *); > extern u_long _create_xid (void); > @@ -186,6 +191,12 @@ clntudp_bufcreate (struct sockaddr_in *r > (void) bindresvport (*sockp, (struct sockaddr_in *) 0); > /* the sockets rpc controls are non-blocking */ > (void) __ioctl (*sockp, FIONBIO, (char *) &dontblock); > +#ifdef IP_RECVERR > + { > + int on = 1; > + setsockopt(*sockp, SOL_IP, IP_RECVERR, &on, sizeof(on)); > + } > +#endif cu-> cu_closeit = TRUE; > } > else > @@ -361,6 +372,47 @@ send_again: cu-> cu_error.re_errno = errno; > return (cu->cu_error.re_status = RPC_CANTRECV); > } > +#ifdef IP_RECVERR > + if (fd.revents & POLLERR) > + { > + struct msghdr msg; > + struct cmsghdr *cmsg; > + struct sock_extended_err *e; > + struct sockaddr_in err_addr; > + struct iovec iov; > + char *cbuf = (char *) alloca (outlen + 256); > + int ret; > + > + iov.iov_base = cbuf + 256; > + iov.iov_len = outlen; > + msg.msg_name = (void *) &err_addr; > + msg.msg_namelen = sizeof (err_addr); > + msg.msg_iov = &iov; > + msg.msg_iovlen = 1; > + msg.msg_flags = 0; > + msg.msg_control = cbuf; > + msg.msg_controllen = 256; > + ret = recvmsg (cu->cu_sock, &msg, MSG_ERRQUEUE); > + if ((ret == 0 > + || (ret == outlen > + && memcmp (cbuf + 256, cu->cu_outbuf, outlen) == 0)) Andi Kleen told me that ret == 0 doesn't make sense since that would mean that the error queue is empty. The outlen check is also wrong since ICMP can shorten packages. He advices to use: if ((ret >= SUNRPC_MIN_HDR && memcpy(cbuf+256,cu->cu_outbuf,outlen) == 0) where SUNRPC_MIN_HDR is a minimal value we will use for comparison. Andreas -- Andreas Jaeger SuSE Labs aj@suse.de private aj@arthur.inka.de http://www.suse.de/~aj
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