From: "J. Bruce Fields" Subject: Re: [PATCH 04/14] text-based mount command: get_client_address support for IPv6 Date: Thu, 10 Jul 2008 15:30:08 -0400 Message-ID: <20080710193008.GA27734@fieldses.org> References: <20080710001725.6137.83845.stgit@tarkus.1015granger.net> <20080710003723.6137.51761.stgit@tarkus.1015granger.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: steved@redhat.com, linux-nfs@vger.kernel.org To: Chuck Lever Return-path: Received: from mail.fieldses.org ([66.93.2.214]:54696 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756502AbYGJTaU (ORCPT ); Thu, 10 Jul 2008 15:30:20 -0400 In-Reply-To: <20080710003723.6137.51761.stgit-lQeC5l55kZ7wdl/1UfZZQIVfYA8g3rJ/@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Jul 09, 2008 at 08:37:24PM -0400, Chuck Lever wrote: > Introduce IPv6-enabled version of get_client_address. The legacy mount > command could use this eventually as well. > > I don't remember how to tell an NFSv4 server to disable the callback > channel: whether an ANY address is passed with SETCLIENTID, or a > loopback address is passed. The patch allows either to be used with a > compile-time switch. I would have thought INADDR_ANY. But in any case we should just pick one.... --b. > > Signed-off-by: Chuck Lever > --- > > utils/mount/network.c | 122 +++++++++++++++++++++++++++++++++++++++++++++++++ > utils/mount/network.h | 2 + > 2 files changed, 124 insertions(+), 0 deletions(-) > > diff --git a/utils/mount/network.c b/utils/mount/network.c > index 3f2721b..128d7f7 100644 > --- a/utils/mount/network.c > +++ b/utils/mount/network.c > @@ -918,3 +918,125 @@ int get_client_address(struct sockaddr_in *saddr, struct sockaddr_in *caddr) > } > return 1; > } > + > +/* > + * Try a getsockname() on a connected datagram socket. > + * > + * Returns 1 and fills in @buf if successful; otherwise, zero. > + * > + * A connected datagram socket prevents leaving a socket in TIME_WAIT. > + * This conserves the ephemeral port number space, helping reduce failed > + * socket binds during mount storms. > + */ > +static int nfs_ca_sockname(const struct sockaddr *sap, const socklen_t salen, > + struct sockaddr *buf, socklen_t *buflen) > +{ > + struct sockaddr_in sin = { > + .sin_family = AF_INET, > + .sin_addr.s_addr = htonl(INADDR_ANY), > + }; > + struct sockaddr_in6 sin6 = { > + .sin6_family = AF_INET6, > + .sin6_addr = IN6ADDR_ANY_INIT, > + }; > + int sock; > + > + sock = socket(sap->sa_family, SOCK_DGRAM, IPPROTO_UDP); > + if (sock < 0) > + return 0; > + > + switch (sap->sa_family) { > + case AF_INET: > + if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) < 0) { > + close(sock); > + return 0; > + } > + break; > + case AF_INET6: > + if (bind(sock, (struct sockaddr *)&sin6, sizeof(sin6)) < 0) { > + close(sock); > + return 0; > + } > + break; > + default: > + errno = EAFNOSUPPORT; > + return 0; > + } > + > + if (connect(sock, sap, salen) < 0) { > + close(sock); > + return 0; > + } > + > + return !getsockname(sock, buf, buflen); > +} > + > +/* > + * Try to generate an address that prevents the server from calling us. > + * > + * Returns 1 and fills in @buf if successful; otherwise, zero. > + */ > +static int nfs_ca_gai(const struct sockaddr *sap, const socklen_t salen, > + struct sockaddr *buf, socklen_t *buflen) > +{ > + struct addrinfo *gai_results; > + struct addrinfo gai_hint = { > + .ai_family = sap->sa_family, > +#ifdef GENERATE_LOOPBACK_ADDRESS > + .ai_flags = 0, /* loopback */ > +#else > + .ai_flags = AI_PASSIVE, /* ANYADDR */ > +#endif > + }; > + > + if (getaddrinfo(NULL, "", &gai_hint, &gai_results)) > + return 0; > + > + *buflen = gai_results->ai_addrlen; > + memcpy(buf, gai_results->ai_addr, *buflen); > + > + freeaddrinfo(gai_results); > + > + return 1; > +} > + > +/** > + * nfs_callback_address - acquire our local network address > + * @sap: pointer to address of remote > + * @sap_len: length of address > + * @buf: pointer to buffer to be filled in with local network address > + * @buflen: IN: length of buffer to fill in; OUT: length of filled-in address > + * > + * Discover a network address that an NFSv4 server can use to call us back. > + * On multi-homed clients, this address depends on which NIC we use to > + * route requests to the server. > + * > + * Returns 1 and fills in @buf if an unambiguous local address is > + * available; returns 1 and fills in an appropriate ANYADDR address > + * if a local address isn't available; otherwise, returns zero. > + */ > +int nfs_callback_address(const struct sockaddr *sap, const socklen_t salen, > + struct sockaddr *buf, socklen_t *buflen) > +{ > + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf; > + > + if (nfs_ca_sockname(sap, salen, buf, buflen) == 0) > + if (nfs_ca_gai(sap, salen, buf, buflen) == 0) > + goto out_failed; > + > + /* > + * The server can't use an interface ID that was generated > + * here on the client, so always clear sin6_scope_id. > + */ > + if (sin6->sin6_family == AF_INET6) > + sin6->sin6_scope_id = 0; > + > + return 1; > + > +out_failed: > + *buflen = 0; > + if (verbose) > + nfs_error(_("%s: failed to construct callback address")); > + return 0; > + > +} > diff --git a/utils/mount/network.h b/utils/mount/network.h > index 8da7e20..2f4ff3a 100644 > --- a/utils/mount/network.h > +++ b/utils/mount/network.h > @@ -58,6 +58,8 @@ int nfs_string_to_sockaddr(const char *, const size_t, > int nfs_present_sockaddr(const struct sockaddr *, > const socklen_t, char *, const size_t); > int get_client_address(struct sockaddr_in *, struct sockaddr_in *); > +int nfs_callback_address(const struct sockaddr *, const socklen_t, > + struct sockaddr *, socklen_t *); > int nfs_call_umount(clnt_addr_t *, dirpath *); > int clnt_ping(struct sockaddr_in *, const unsigned long, > const unsigned long, const unsigned int, > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html