[PATCH] rpcbind: add support for systemd socket activation

[Steve Dickson <steved@redhat.com>]

From: Tom Gundersen <teg@jklm.no>

Making rpcbind sockect activated will greatly simplify
its integration in systemd systems. In essence, other services
may now assume that rpcbind is always available, even during very
early boot. This means that we no longer need to worry about any
ordering dependencies.

This is based on a patch originally posted by Lennart Poettering:
<http://permalink.gmane.org/gmane.linux.nfs/33774>.

That patch was not merged due to the lack of a shared library and
as systemd was seen to be too Fedora specific.

Systemd now provides a shared library, and it is (or very soon will
be) the default init system on all the major Linux distributions.

This version of the patch has three changes from the original:

 * It uses the shared library.
 * It comes with unit files.
 * It is rebased on top of master.

Please review the patch with "git show -b" or otherwise ignoring the
whitespace changes, or it will be extremely difficult to read.

v4: reorganized the changes to make the diff easier to read
    remove systemd scripts.

v3: rebase
    fix typos
    listen on /run/rpcbind.sock, rather than /var/run/rpcbind.sock (the
    latter is a symlink to the former, but this means the socket can be
    created before /var is mounted)
    NB: this version has been compile-tested only as I no longer use
    rpcbind myself
v2: correctly enable systemd code at compile time
    handle the case where not all the required sockets were supplied
    listen on udp/tcp port 111 in addition to /var/run/rpcbind.sock
    do not daemonize

Original-patch-by: Lennart Poettering <lennart@poettering.net>
Cc: Steve Dickson <steved@redhat.com>
Cc: systemd-devel@lists.freedesktop.org
Acked-by: Cristian Rodríguez<crrodriguez@opensuse.org>
Signed-off-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: Steve Dickson <steved@redhat.com>
---
 Makefile.am   |  6 +++++
 configure.ac  | 10 ++++++++
 src/rpcbind.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 91 insertions(+), 6 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index 8715082..c99566d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -41,6 +41,12 @@ rpcbind_SOURCES = \
 	src/warmstart.c
 rpcbind_LDADD = $(TIRPC_LIBS)
 
+if SYSTEMD
+AM_CPPFLAGS += $(SYSTEMD_CFLAGS) -DSYSTEMD
+
+rpcbind_LDADD += $(SYSTEMD_LIBS)
+endif
+
 rpcinfo_SOURCES =       src/rpcinfo.c
 rpcinfo_LDADD   =       $(TIRPC_LIBS)
 
diff --git a/configure.ac b/configure.ac
index 5a88cc7..fdad639 100644
--- a/configure.ac
+++ b/configure.ac
@@ -36,6 +36,16 @@ AC_SUBST([nss_modules], [$with_nss_modules])
 
 PKG_CHECK_MODULES([TIRPC], [libtirpc])
 
+PKG_PROG_PKG_CONFIG
+AC_ARG_WITH([systemdsystemunitdir],
+  AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for systemd service files]),
+  [], [with_systemdsystemunitdir=$($PKG_CONFIG --variable=systemdsystemunitdir systemd)])
+  if test "x$with_systemdsystemunitdir" != xno; then
+    AC_SUBST([systemdsystemunitdir], [$with_systemdsystemunitdir])
+    PKG_CHECK_MODULES([SYSTEMD], [libsystemd-daemon])
+  fi
+AM_CONDITIONAL(SYSTEMD, [test -n "$with_systemdsystemunitdir" -a "x$with_systemdsystemunitdir" != xno ])
+
 AS_IF([test x$enable_libwrap = xyes], [
 	AC_CHECK_LIB([wrap], [hosts_access], ,
 		AC_MSG_ERROR([libwrap support requested but unable to find libwrap]))
diff --git a/src/rpcbind.c b/src/rpcbind.c
index e3462e3..f7c71ee 100644
--- a/src/rpcbind.c
+++ b/src/rpcbind.c
@@ -56,6 +56,9 @@
 #include <netinet/in.h>
 #endif
 #include <arpa/inet.h>
+#ifdef SYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
 #include <fcntl.h>
 #include <netdb.h>
 #include <stdio.h>
@@ -296,6 +299,7 @@ init_transport(struct netconfig *nconf)
 	u_int32_t host_addr[4];  /* IPv4 or IPv6 */
 	struct sockaddr_un sun;
 	mode_t oldmask;
+	int n;
         res = NULL;
 
 	if ((nconf->nc_semantics != NC_TPI_CLTS) &&
@@ -314,6 +318,76 @@ init_transport(struct netconfig *nconf)
 			fprintf(stderr, "[%d] - %s\n", i, *s);
 	}
 #endif
+	if (!__rpc_nconf2sockinfo(nconf, &si)) {
+		syslog(LOG_ERR, "cannot get information for %s",
+		    nconf->nc_netid);
+		return (1);
+	}
+
+#ifdef SYSTEMD
+	n = sd_listen_fds(0);
+	if (n < 0) {
+		syslog(LOG_ERR, "failed to acquire systemd sockets: %s", strerror(-n));
+		return 1;
+	}
+
+	/* Try to find if one of the systemd sockets we were given match
+	 * our netconfig structure. */
+
+	for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
+		struct __rpc_sockinfo si_other;
+		union {
+			struct sockaddr sa;
+			struct sockaddr_un un;
+			struct sockaddr_in in4;
+			struct sockaddr_in6 in6;
+			struct sockaddr_storage storage;
+		} sa;
+		socklen_t addrlen = sizeof(sa);
+
+		if (!__rpc_fd2sockinfo(fd, &si_other)) {
+			syslog(LOG_ERR, "cannot get information for fd %i", fd);
+			return 1;
+		}
+
+		if (si.si_af != si_other.si_af ||
+                    si.si_socktype != si_other.si_socktype ||
+                    si.si_proto != si_other.si_proto)
+			continue;
+
+		if (getsockname(fd, &sa.sa, &addrlen) < 0) {
+			syslog(LOG_ERR, "failed to query socket name: %s",
+                               strerror(errno));
+			goto error;
+		}
+
+		/* Copy the address */
+		taddr.addr.maxlen = taddr.addr.len = addrlen;
+		taddr.addr.buf = malloc(addrlen);
+		if (taddr.addr.buf == NULL) {
+			syslog(LOG_ERR,
+                               "cannot allocate memory for %s address",
+                               nconf->nc_netid);
+			goto error;
+		}
+		memcpy(taddr.addr.buf, &sa, addrlen);
+
+		my_xprt = (SVCXPRT *)svc_tli_create(fd, nconf, &taddr,
+                          RPC_MAXDATASIZE, RPC_MAXDATASIZE);
+		if (my_xprt == (SVCXPRT *)NULL) {
+			syslog(LOG_ERR, "%s: could not create service",
+                               nconf->nc_netid);
+			goto error;
+		}
+	}
+
+	/*
+	 * If none of the systemd sockets matched, we set up the socket in
+	 * the normal way:
+	 */
+#endif
+	if (my_xprt != NULL)
+		goto got_socket;
 
 	/*
 	 * XXX - using RPC library internal functions. For NC_TPI_CLTS
@@ -327,12 +401,6 @@ init_transport(struct netconfig *nconf)
 		}
 	}
 
-	if (!__rpc_nconf2sockinfo(nconf, &si)) {
-		syslog(LOG_ERR, "cannot get information for %s",
-		    nconf->nc_netid);
-		return (1);
-	}
-
 	if ((strcmp(nconf->nc_netid, "local") == 0) ||
 	    (strcmp(nconf->nc_netid, "unix") == 0)) {
 		memset(&sun, 0, sizeof sun);
@@ -569,6 +637,7 @@ init_transport(struct netconfig *nconf)
 			goto error;
 		}
 	}
+got_socket:
 
 #ifdef PORTMAP
 	/*
-- 
2.1.0