From: Chuck Lever Subject: [PATCH 04/14] text-based mount command: get_client_address support for IPv6 Date: Wed, 09 Jul 2008 20:37:24 -0400 Message-ID: <20080710003723.6137.51761.stgit@tarkus.1015granger.net> References: <20080710001725.6137.83845.stgit@tarkus.1015granger.net> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Cc: linux-nfs@vger.kernel.org To: steved@redhat.com Return-path: Received: from rgminet01.oracle.com ([148.87.113.118]:61667 "EHLO rgminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751083AbYGJEIJ (ORCPT ); Thu, 10 Jul 2008 00:08:09 -0400 In-Reply-To: <20080710001725.6137.83845.stgit-lQeC5l55kZ7wdl/1UfZZQIVfYA8g3rJ/@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: 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. 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,