File nfs-utils-allow-port-number-sharing of Package nfs-utils

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File nfs-utils-allow-port-number-sharing of Package nfs-utils (Revision a2ec6820601008bd5b20f9e7d0466f4b)

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From: Chuck Lever <chuck.lever@oracle.com>
Subject: [PATCH 02/15] libnfs.a: Allow multiple RPC listeners to share
	listener port number
To: steved@redhat.com
Cc: linux-nfs@vger.kernel.org
Date:	Sun, 10 Oct 2010 20:04:21 -0400
Message-ID: <20101011000421.6667.60700.stgit@ellison.1015granger.net>
In-Reply-To: <20101010234836.6667.4057.stgit@ellison.1015granger.net>
References: <20101010234836.6667.4057.stgit@ellison.1015granger.net>
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Normally, when "-p" is not specified on the mountd command line, the
TI-RPC library chooses random port numbers for each listener.  If a
port number _is_ specified on the command line, all the listeners
will get the same port number, so SO_REUSEADDR needs to be set on
each socket.

Thus we can't let TI-RPC create the listener sockets for us in this
case; we must create them ourselves and then set SO_REUSEADDR (and
other socket options) by hand.

Different versions of the same RPC program have to share the same
listener and SVCXPRT, so we have to cache xprts we create, and re-use
them when additional requests for registration come from the
application.

Though it doesn't look like it, this fix was "copied" from the legacy
rpc_init() function.  It's more complicated for TI-RPC, of course,
since a TI-RPC application can set up listeners with a nearly
arbitrary number of address families and socket types, not just the
two listeners that legacy RPC applications can set up (one for AF_INET
UDP and one for AF_INET TCP).

See:
  https://bugzilla.linux-nfs.org/show_bug.cgi?id=190

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---

support/nfs/svc_create.c |  252 +++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 246 insertions(+), 6 deletions(-)

diff --git a/support/nfs/svc_create.c b/support/nfs/svc_create.c
index 59ba505..b3f75ed 100644
--- a/support/nfs/svc_create.c
+++ b/support/nfs/svc_create.c
@@ -27,6 +27,7 @@
 #include <memory.h>
 #include <signal.h>
 #include <unistd.h>
+#include <errno.h>
 #include <netdb.h>
 
 #include <netinet/in.h>
@@ -41,11 +42,68 @@
 #include "tcpwrapper.h"
 #endif
 
+#include "sockaddr.h"
 #include "rpcmisc.h"
 #include "xlog.h"
 
 #ifdef HAVE_LIBTIRPC
 
+#define SVC_CREATE_XPRT_CACHE_SIZE	(8)
+static SVCXPRT *svc_create_xprt_cache[SVC_CREATE_XPRT_CACHE_SIZE] = { NULL, };
+
+/*
+ * Cache an SVC xprt, in case there are more programs or versions to
+ * register against it.
+ */
+static void
+svc_create_cache_xprt(SVCXPRT *xprt)
+{
+	unsigned int i;
+
+	/* Check if we've already got this one... */
+	for (i = 0; i < SVC_CREATE_XPRT_CACHE_SIZE; i++)
+		if (svc_create_xprt_cache[i] == xprt)
+			return;
+
+	/* No, we don't.  Cache it. */
+	for (i = 0; i < SVC_CREATE_XPRT_CACHE_SIZE; i++)
+		if (svc_create_xprt_cache[i] == NULL) {
+			svc_create_xprt_cache[i] = xprt;
+			return;
+		}
+
+	xlog(L_ERROR, "%s: Failed to cache an xprt", __func__);
+}
+
+/*
+ * Find a previously cached SVC xprt structure with the given bind address
+ * and transport semantics.
+ *
+ * Returns pointer to a cached SVC xprt.
+ *
+ * If no matching SVC XPRT can be found, NULL is returned.
+ */
+static SVCXPRT *
+svc_create_find_xprt(const struct sockaddr *bindaddr, const struct netconfig *nconf)
+{
+	unsigned int i;
+
+	for (i = 0; i < SVC_CREATE_XPRT_CACHE_SIZE; i++) {
+		SVCXPRT *xprt = svc_create_xprt_cache[i];
+		struct sockaddr *sap;
+
+		if (xprt == NULL)
+			continue;
+		if (strcmp(nconf->nc_netid, xprt->xp_netid) != 0)
+			continue;
+		sap = (struct sockaddr *)xprt->xp_ltaddr.buf;
+		if (!nfs_compare_sockaddr(bindaddr, sap))
+			continue;
+		return xprt;
+	}
+	return NULL;
+}
+
 /*
  * Set up an appropriate bind address, given @port and @nconf.
  *
@@ -98,17 +156,113 @@ svc_create_bindaddr(struct netconfig *nconf, const uint16_t port)
 	return ai;
 }
 
+/*
+ * Create a listener socket on a specific bindaddr, and set
+ * special socket options to allow it to share the same port
+ * as other listeners.
+ *
+ * Returns an open, bound, and possibly listening network
+ * socket on success.
+ *
+ * Otherwise returns -1 if some error occurs.
+ */
+static int
+svc_create_sock(const struct sockaddr *sap, socklen_t salen,
+		struct netconfig *nconf)
+{
+	int fd, type, protocol;
+	int one = 1;
+
+	switch(nconf->nc_semantics) {
+	case NC_TPI_CLTS:
+		type = SOCK_DGRAM;
+		break;
+	case NC_TPI_COTS_ORD:
+		type = SOCK_STREAM;
+		break;
+	default:
+		xlog(D_GENERAL, "%s: Unrecognized bind address semantics: %u",
+			__func__, nconf->nc_semantics);
+		return -1;
+	}
+
+	if (strcmp(nconf->nc_proto, NC_UDP) == 0)
+		protocol = (int)IPPROTO_UDP;
+	else if (strcmp(nconf->nc_proto, NC_TCP) == 0)
+		protocol = (int)IPPROTO_TCP;
+	else {
+		xlog(D_GENERAL, "%s: Unrecognized bind address protocol: %s",
+			__func__, nconf->nc_proto);
+		return -1;
+	}
+
+	fd = socket((int)sap->sa_family, type, protocol);
+	if (fd == -1) {
+		xlog(L_ERROR, "Could not make a socket: (%d) %m",
+			errno);
+		return -1;
+	}
+
+#ifdef IPV6_SUPPORTED
+	if (sap->sa_family == AF_INET6) {
+		if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY,
+				&one, sizeof(one)) == -1) {
+			xlog(L_ERROR, "Failed to set IPV6_V6ONLY: (%d) %m",
+				errno);
+			(void)close(fd);
+			return -1;
+		}
+	}
+#endif	/* IPV6_SUPPORTED */
+
+	if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
+		       &one, sizeof(one)) == -1) {
+		xlog(L_ERROR, "Failed to set SO_REUSEADDR: (%d) %m",
+			errno);
+		(void)close(fd);
+		return -1;
+	}
+
+	if (bind(fd, sap, salen) == -1) {
+		xlog(L_ERROR, "Could not bind socket: (%d) %m",
+			errno);
+		(void)close(fd);
+		return -1;
+	}
+
+	if (nconf->nc_semantics == NC_TPI_COTS_ORD)
+		if (listen(fd, SOMAXCONN) == -1) {
+			xlog(L_ERROR, "Could not listen on socket: (%d) %m",
+				errno);
+			(void)close(fd);
+			return -1;
+		}
+
+	return fd;
+}
+
+/*
+ * The simple case is allowing the TI-RPC library to create a
+ * transport itself, given just the bind address and transport
+ * semantics.
+ *
+ * Our local xprt cache is ignored in this path, since the
+ * caller is not interested in sharing listeners or ports, and
+ * the library automatically avoids ports already in use.
+ *
+ * Returns the count of started listeners (one or zero).
+ */
 static unsigned int
-svc_create_nconf(const char *name, const rpcprog_t program,
+svc_create_nconf_rand_port(const char *name, const rpcprog_t program,
 		const rpcvers_t version,
 		void (*dispatch)(struct svc_req *, SVCXPRT *),
-		const uint16_t port, struct netconfig *nconf)
+		struct netconfig *nconf)
 {
 	struct t_bind bindaddr;
 	struct addrinfo *ai;
 	SVCXPRT	*xprt;
 
-	ai = svc_create_bindaddr(nconf, port);
+	ai = svc_create_bindaddr(nconf, 0);
 	if (ai == NULL)
 		return 0;
 
@@ -119,7 +273,7 @@ svc_create_nconf(const char *name, const rpcprog_t program,
 	freeaddrinfo(ai);
 	if (xprt == NULL) {
 		xlog(D_GENERAL, "Failed to create listener xprt "
-				"(%s, %u, %s)", name, version, nconf->nc_netid);
+			"(%s, %u, %s)", name, version, nconf->nc_netid);
 		return 0;
 	}
 
@@ -133,6 +287,93 @@ svc_create_nconf(const char *name, const rpcprog_t program,
 	return 1;
 }
 
+/*
+ * If a port is specified on the command line, that port value will be
+ * the same for all listeners created here.  Create each listener
+ * socket in advance and set SO_REUSEADDR, rather than allowing the
+ * RPC library to create the listeners for us on a randomly chosen
+ * port via svc_tli_create(RPC_ANYFD).
+ *
+ * Some callers want to listen for more than one RPC version using the
+ * same port number.  For example, mountd could want to listen for MNT
+ * version 1, 2, and 3 requests.  This means mountd must use the same
+ * set of listener sockets for multiple RPC versions, since, on one
+ * system, you can't have two listener sockets with the exact same
+ * bind address (and port) and transport protocol.
+ *
+ * To accomplish this, this function caches xprts as they are created.
+ * This cache is checked to see if a previously created xprt can be
+ * used, before creating a new xprt for this [program, version].  If
+ * there is a cached xprt with the same bindaddr and transport
+ * semantics, we simply register the new version with that xprt,
+ * rather than creating a fresh xprt for it.
+ *
+ * The xprt cache implemented here is local to a process.  Two
+ * separate RPC daemons can not share a set of listeners.
+ *
+ * Returns the count of started listeners (one or zero).
+ */
+static unsigned int
+svc_create_nconf_fixed_port(const char *name, const rpcprog_t program,
+		const rpcvers_t version,
+		void (*dispatch)(struct svc_req *, SVCXPRT *),
+		const uint16_t port, struct netconfig *nconf)
+{
+	struct addrinfo *ai;
+	SVCXPRT	*xprt;
+
+	ai = svc_create_bindaddr(nconf, port);
+	if (ai == NULL)
+		return 0;
+
+	xprt = svc_create_find_xprt(ai->ai_addr, nconf);
+	if (xprt == NULL) {
+		int fd;
+
+		fd = svc_create_sock(ai->ai_addr, ai->ai_addrlen, nconf);
+		if (fd == -1)
+			goto out_free;
+
+		xprt = svc_tli_create(fd, nconf, NULL, 0, 0);
+		if (xprt == NULL) {
+			xlog(D_GENERAL, "Failed to create listener xprt "
+				"(%s, %u, %s)", name, version, nconf->nc_netid);
+			(void)close(fd);
+			goto out_free;
+		}
+	}
+
+	if (!svc_reg(xprt, program, version, dispatch, nconf)) {
+		/* svc_reg(3) destroys @xprt in this case */
+		xlog(D_GENERAL, "Failed to register (%s, %u, %s)",
+				name, version, nconf->nc_netid);
+		goto out_free;
+	}
+
+	svc_create_cache_xprt(xprt);
+
+	freeaddrinfo(ai);
+	return 1;
+
+out_free:
+	freeaddrinfo(ai);
+	return 0;
+}
+
+static unsigned int
+svc_create_nconf(const char *name, const rpcprog_t program,
+		const rpcvers_t version,
+		void (*dispatch)(struct svc_req *, SVCXPRT *),
+		const uint16_t port, struct netconfig *nconf)
+{
+	if (port != 0)
+		return svc_create_nconf_fixed_port(name, program,
+			version, dispatch, port, nconf);
+
+	return svc_create_nconf_rand_port(name, program,
+			version, dispatch, nconf);
+}
+
 /**
  * nfs_svc_create - start up RPC svc listeners
  * @name: C string containing name of new service
@@ -145,8 +386,7 @@ svc_create_nconf(const char *name, const rpcprog_t program,
  * the RPC dispatcher.  Returns the number of started network transports.
  */
 unsigned int
-nfs_svc_create(__attribute__((unused)) char *name,
-		const rpcprog_t program, const rpcvers_t version,
+nfs_svc_create(char *name, const rpcprog_t program, const rpcvers_t version,
 		void (*dispatch)(struct svc_req *, SVCXPRT *),
 		const uint16_t port)
 {

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