Systemd support backported from the master branch as of 23/04/2012 (post 5.7.1, pre 5.8).

The following commits have been cherry-picked:

19499c3c90bf9d7b2b9e5d08baa26cc6bba28a11
fef6cddfdb94da1a6b1fb768af62918b80f11fd3
0641e43c694c485cbbffef0556efc4641bd3ff50
76530a89f1c8bbd0b63acce63e10d5d4812a1a16 (conflict resolved)
bf108d7f1354f6276fc43c129963f2c49b9fc242
74412748067c685e1d8ab6ed3bcc3ca9c2774844
86132e3f1e6ef7b4e0b96d8fa24e37c81b71b0e0
63557cf8986a33dba1d4429b583a901361052c4f

Upstream-Status: Backport

diff --git a/README.systemd b/README.systemd
new file mode 100644
index 0000000..f731851
--- /dev/null
+++ b/README.systemd
@@ -0,0 +1,41 @@
+README.systemd
+--------------
+Net-SNMP provides two daemons, which support systemd system manager. 
+See http://www.freedesktop.org/wiki/Software/systemd to learn how
+systemd works. Both socket activation and notification is supported by these
+daemons.
+
+To enable systemd support, the sources must be compiled with
+--with-systemd configure option.
+
+snmpd - The SNMP agent
+----------------------
+Socket activation od snmpd daemon is implemented, but it's discouraged.
+The reason is simple - snmpd not only listens and processes SNMP requests
+from network, but also gathers system statistics counters, sends traps and
+communicates with subagents. It even opens few netlink sockets.
+
+In other words, snmpd should run from system start to properly work.
+This can be done in two ways:
+1) either as snmpd service unit with 'Type=notification' and without a socket
+   unit
+2) or as snmpd service unit with 'Type=simple', appropriate socket socket unit
+   and the snmpd service enabled. This way systemd creates the snmpd listening
+   socket early during boot and passes the sockets to snmpd slightly later
+   (but still during machine boot). This way systemd can paralelize start of
+   services, which depend on snmpd. Admins must adjust the socket file manually,
+   depending if the snmpd support AgentX, IPv6, SMUX etc.
+
+snmpd should be started with '-f' command line parameter to disable forking -
+systemd does that for us automatically.
+
+
+snmptrapd - The trap processing daemon
+--------------------------------------
+snmptrapd supports full socket activation and also notification (if needed).
+Both 'Type=simple' (with appropriate socket unit) and 'Type=notify' services
+will work. Again, '-f' parameter should be provided on snmptrapd command line.
+
+If integration with SNMP agent using AgentX protocol is enabled, snmptrapd should
+start during boot and not after first SNMP trap arrives. Same rules as for snmpd
+applies then.
\ No newline at end of file
diff --git a/agent/snmpd.c b/agent/snmpd.c
index b177d5b..08bdfc7 100644
--- a/agent/snmpd.c
+++ b/agent/snmpd.c
@@ -164,6 +164,10 @@ typedef long    fd_mask;
 
 #endif
 
+#ifndef NETSNMP_NO_SYSTEMD
+#include <net-snmp/library/sd-daemon.h>
+#endif
+
 netsnmp_feature_want(logging_file)
 netsnmp_feature_want(logging_stdio)
 netsnmp_feature_want(logging_syslog)
@@ -441,18 +445,28 @@ main(int argc, char *argv[])
     int             agent_mode = -1;
     char           *pid_file = NULL;
     char            option_compatability[] = "-Le";
+#ifndef WIN32
+    int             prepared_sockets = 0;
+#endif
 #if HAVE_GETPID
     int fd;
     FILE           *PID;
 #endif
 
 #ifndef WIN32
+#ifndef NETSNMP_NO_SYSYSTEMD
+    /* check if systemd has sockets for us and don't close them */
+    prepared_sockets = netsnmp_sd_listen_fds(0);
+#endif /* NETSNMP_NO_SYSYSTEMD */
+
     /*
      * close all non-standard file descriptors we may have
      * inherited from the shell.
      */
-    for (i = getdtablesize() - 1; i > 2; --i) {
-        (void) close(i);
+    if (!prepared_sockets) {
+        for (i = getdtablesize() - 1; i > 2; --i) {
+            (void) close(i);
+        }
     }
 #endif /* #WIN32 */
     
@@ -1100,6 +1114,19 @@ main(int argc, char *argv[])
     netsnmp_addrcache_initialise();
 
     /*
+     * Let systemd know we're up.
+     */
+#ifndef NETSNMP_NO_SYSTEMD
+    netsnmp_sd_notify(1, "READY=1\n");
+    if (prepared_sockets)
+        /*
+         * Clear the environment variable, we already processed all the sockets
+         * by now.
+         */
+        netsnmp_sd_listen_fds(1);
+#endif
+
+    /*
      * Forever monitor the dest_port for incoming PDUs.  
      */
     DEBUGMSGTL(("snmpd/main", "We're up.  Starting to process data.\n"));
diff --git a/apps/snmptrapd.c b/apps/snmptrapd.c
index 1a52080..0857ae1 100644
--- a/apps/snmptrapd.c
+++ b/apps/snmptrapd.c
@@ -125,6 +125,10 @@ SOFTWARE.
 
 #include <net-snmp/net-snmp-features.h>
 
+#ifndef NETSNMP_NO_SYSTEMD
+#include <net-snmp/library/sd-daemon.h>
+#endif
+
 #ifndef BSD4_3
 #define BSD4_2
 #endif
@@ -655,15 +659,24 @@ main(int argc, char *argv[])
     int             agentx_subagent = 1;
 #endif
     netsnmp_trapd_handler *traph;
+#ifndef WIN32
+    int             prepared_sockets = 0;
+#endif
 
 
 #ifndef WIN32
+#ifndef NETSNMP_NO_SYSTEMD
+    /* check if systemd has sockets for us and don't close them */
+    prepared_sockets = netsnmp_sd_listen_fds(0);
+#endif
     /*
      * close all non-standard file descriptors we may have
      * inherited from the shell.
      */
-    for (i = getdtablesize() - 1; i > 2; --i) {
-        (void) close(i);
+    if (!prepared_sockets) {
+        for (i = getdtablesize() - 1; i > 2; --i) {
+            (void) close(i);
+        }
     }
 #endif /* #WIN32 */
     
@@ -1311,6 +1324,19 @@ main(int argc, char *argv[])
 #endif
 #endif
 
+    /*
+     * Let systemd know we're up.
+     */
+#ifndef NETSNMP_NO_SYSTEMD
+    netsnmp_sd_notify(1, "READY=1\n");
+    if (prepared_sockets)
+        /*
+         * Clear the environment variable, we already processed all the sockets
+         * by now.
+         */
+        netsnmp_sd_listen_fds(1);
+#endif
+
 #ifdef WIN32SERVICE
     trapd_status = SNMPTRAPD_RUNNING;
 #endif
diff --git a/configure.d/config_modules_lib b/configure.d/config_modules_lib
index b6609c1..5849072 100644
--- a/configure.d/config_modules_lib
+++ b/configure.d/config_modules_lib
@@ -53,6 +53,14 @@ if test "x$PARTIALTARGETOS" = "xmingw32" -o "x$PARTIALTARGETOS" = "xmingw32msvc"
   other_ftobjs_list="$other_ftobjs_list winpipe.ft"
 fi
 
+# Linux systemd
+if test "x$with_systemd" == "xyes"; then
+  other_src_list="$other_src_list sd-daemon.c"
+  other_objs_list="$other_objs_list sd-daemon.o"
+  other_lobjs_list="$other_lobjs_list sd-daemon.lo"
+  other_ftobjs_list="$other_ftobjs_list sd-daemon.ft"
+fi
+
 AC_SUBST(other_src_list)
 AC_SUBST(other_objs_list)
 AC_SUBST(other_lobjs_list)
diff --git a/configure.d/config_project_with_enable b/configure.d/config_project_with_enable
index 8b46ad2..59d6d5c 100644
--- a/configure.d/config_project_with_enable
+++ b/configure.d/config_project_with_enable
@@ -689,6 +689,15 @@ if test "x$with_dummy_values" != "xyes"; then
      data for])
 fi
 
+NETSNMP_ARG_WITH(systemd,
+[  --with-systemd                 Provide systemd support. See README.systemd
+                                  for details.])
+# Define unless specifically suppressed (i.e., option defaults to false).
+if test "x$with_systemd" != "xyes"; then
+  AC_DEFINE(NETSNMP_NO_SYSTEMD, 1,
+    [If you don't want to integrate with systemd.])
+fi
+
 NETSNMP_ARG_ENABLE(set-support,
 [  --disable-set-support           Do not allow SNMP set requests.])
 if test "x$enable_set_support" = "xno"; then
diff --git a/dist/snmpd.service b/dist/snmpd.service
new file mode 100644
index 0000000..31391e5
--- /dev/null
+++ b/dist/snmpd.service
@@ -0,0 +1,18 @@
+#
+# SNMP agent service file for systemd
+#
+#
+# The service should be enabled, i.e. snmpd should start during machine boot.
+# Socket activation shall not be used. See README.systemd for details.
+
+[Unit]
+Description=Simple Network Management Protocol (SNMP) daemon.
+After=syslog.target network.target
+
+[Service]
+# Type=notify is also supported. It should be set when snmpd.socket is not used.
+Type=simple
+ExecStart=/usr/sbin/snmpd -f
+
+[Install]
+WantedBy=multi-user.target
diff --git a/dist/snmpd.socket b/dist/snmpd.socket
new file mode 100644
index 0000000..7f3a2d9
--- /dev/null
+++ b/dist/snmpd.socket
@@ -0,0 +1,17 @@
+[Unit]
+Description=Socket listening for SNMP and AgentX messages
+
+[Socket]
+ListenDatagram=0.0.0.0:161
+# Uncomment other listening addresses as needed - TCP, UDP6, TCP6.
+# It must match listening addresses/ports defined in snmpd.service
+# or snmpd.conf.
+# ListenStream=0.0.0.0:161
+# ListenDatagram=[::]:161
+# ListenStream=[::]:161
+#
+# Uncomment AgentX socket if snmpd.conf enables AgentX protocol.
+# ListenStream=/var/agentx/master
+
+[Install]
+WantedBy=sockets.target
diff --git a/dist/snmptrapd.service b/dist/snmptrapd.service
new file mode 100644
index 0000000..e88a5b4
--- /dev/null
+++ b/dist/snmptrapd.service
@@ -0,0 +1,16 @@
+#
+# SNMP trap-processing service file for systemd
+#
+
+[Unit]
+Description=Simple Network Management Protocol (SNMP) Trap daemon.
+After=syslog.target network.target
+
+[Service]
+# Type=notify is also supported. It should be set when snmptrapd.socket is not
+# used.
+Type=simple
+ExecStart=/usr/sbin/snmptrapd -f
+
+[Install]
+WantedBy=multi-user.target
diff --git a/dist/snmptrapd.socket b/dist/snmptrapd.socket
new file mode 100644
index 0000000..0fc8a7c
--- /dev/null
+++ b/dist/snmptrapd.socket
@@ -0,0 +1,14 @@
+[Unit]
+Description=Socket listening for SNMP trap messages
+
+[Socket]
+ListenDatagram=0.0.0.0:162
+# Uncomment other listening addresses as needed - TCP, UDP6, TCP6.
+# It must match listening addresses/ports defined in snmptrapd.service
+# or snmptrapd.conf.
+# ListenStream=0.0.0.0:162
+# ListenDatagram=[::]:162
+# ListenStream=[::]:162
+
+[Install]
+WantedBy=sockets.target
diff --git a/include/net-snmp/library/sd-daemon.h b/include/net-snmp/library/sd-daemon.h
new file mode 100644
index 0000000..85274c9
--- /dev/null
+++ b/include/net-snmp/library/sd-daemon.h
@@ -0,0 +1,290 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#ifndef SNMPD_SD_DAEMON_H
+#define SNMPD_SD_DAEMON_H
+
+/***
+  Copyright 2010 Lennart Poettering
+
+  Permission is hereby granted, free of charge, to any person
+  obtaining a copy of this software and associated documentation files
+  (the "Software"), to deal in the Software without restriction,
+  including without limitation the rights to use, copy, modify, merge,
+  publish, distribute, sublicense, and/or sell copies of the Software,
+  and to permit persons to whom the Software is furnished to do so,
+  subject to the following conditions:
+
+  The above copyright notice and this permission notice shall be
+  included in all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+  SOFTWARE.
+***/
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_INTTYPES_H
+#include <inttypes.h>
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+  Reference implementation of a few systemd related interfaces for
+  writing daemons. These interfaces are trivial to implement. To
+  simplify porting we provide this reference implementation.
+  Applications are welcome to reimplement the algorithms described
+  here if they do not want to include these two source files.
+
+  The following functionality is provided:
+
+  - Support for logging with log levels on stderr
+  - File descriptor passing for socket-based activation
+  - Daemon startup and status notification
+  - Detection of systemd boots
+
+  You may compile this with -DDISABLE_SYSTEMD to disable systemd
+  support. This makes all those calls NOPs that are directly related to
+  systemd (i.e. only sd_is_xxx() will stay useful).
+
+  Since this is drop-in code we don't want any of our symbols to be
+  exported in any case. Hence we declare hidden visibility for all of
+  them.
+
+  You may find an up-to-date version of these source files online:
+
+  http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.h
+  http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.c
+
+  This should compile on non-Linux systems, too, but with the
+  exception of the sd_is_xxx() calls all functions will become NOPs.
+
+  See sd-daemon(7) for more information.
+*/
+
+#ifndef _sd_printf_attr_
+#if __GNUC__ >= 4
+#define _sd_printf_attr_(a,b) __attribute__ ((format (printf, a, b)))
+#else
+#define _sd_printf_attr_(a,b)
+#endif
+#endif
+
+/*
+  Log levels for usage on stderr:
+
+          fprintf(stderr, SD_NOTICE "Hello World!\n");
+
+  This is similar to printk() usage in the kernel.
+*/
+#define SD_EMERG   "<0>"  /* system is unusable */
+#define SD_ALERT   "<1>"  /* action must be taken immediately */
+#define SD_CRIT    "<2>"  /* critical conditions */
+#define SD_ERR     "<3>"  /* error conditions */
+#define SD_WARNING "<4>"  /* warning conditions */
+#define SD_NOTICE  "<5>"  /* normal but significant condition */
+#define SD_INFO    "<6>"  /* informational */
+#define SD_DEBUG   "<7>"  /* debug-level messages */
+
+/* The first passed file descriptor is fd 3 */
+#define SD_LISTEN_FDS_START 3
+
+/*
+  Returns how many file descriptors have been passed, or a negative
+  errno code on failure. Optionally, removes the $LISTEN_FDS and
+  $LISTEN_PID file descriptors from the environment (recommended, but
+  problematic in threaded environments). If r is the return value of
+  this function you'll find the file descriptors passed as fds
+  SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
+  errno style error code on failure. This function call ensures that
+  the FD_CLOEXEC flag is set for the passed file descriptors, to make
+  sure they are not passed on to child processes. If FD_CLOEXEC shall
+  not be set, the caller needs to unset it after this call for all file
+  descriptors that are used.
+
+  See sd_listen_fds(3) for more information.
+*/
+int netsnmp_sd_listen_fds(int unset_environment);
+
+/*
+  Helper call for identifying a passed file descriptor. Returns 1 if
+  the file descriptor is a FIFO in the file system stored under the
+  specified path, 0 otherwise. If path is NULL a path name check will
+  not be done and the call only verifies if the file descriptor
+  refers to a FIFO. Returns a negative errno style error code on
+  failure.
+
+  See sd_is_fifo(3) for more information.
+*/
+int netsnmp_sd_is_fifo(int fd, const char *path);
+
+/*
+  Helper call for identifying a passed file descriptor. Returns 1 if
+  the file descriptor is a special character device on the file
+  system stored under the specified path, 0 otherwise.
+  If path is NULL a path name check will not be done and the call
+  only verifies if the file descriptor refers to a special character.
+  Returns a negative errno style error code on failure.
+
+  See sd_is_special(3) for more information.
+*/
+int netsnmp_sd_is_special(int fd, const char *path);
+
+/*
+  Helper call for identifying a passed file descriptor. Returns 1 if
+  the file descriptor is a socket of the specified family (AF_INET,
+  ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
+  family is 0 a socket family check will not be done. If type is 0 a
+  socket type check will not be done and the call only verifies if
+  the file descriptor refers to a socket. If listening is > 0 it is
+  verified that the socket is in listening mode. (i.e. listen() has
+  been called) If listening is == 0 it is verified that the socket is
+  not in listening mode. If listening is < 0 no listening mode check
+  is done. Returns a negative errno style error code on failure.
+
+  See sd_is_socket(3) for more information.
+*/
+int netsnmp_sd_is_socket(int fd, int family, int type, int listening);
+
+/*
+  Helper call for identifying a passed file descriptor. Returns 1 if
+  the file descriptor is an Internet socket, of the specified family
+  (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
+  SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
+  check is not done. If type is 0 a socket type check will not be
+  done. If port is 0 a socket port check will not be done. The
+  listening flag is used the same way as in sd_is_socket(). Returns a
+  negative errno style error code on failure.
+
+  See sd_is_socket_inet(3) for more information.
+*/
+int netsnmp_sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port);
+
+/*
+  Helper call for identifying a passed file descriptor. Returns 1 if
+  the file descriptor is an AF_UNIX socket of the specified type
+  (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
+  a socket type check will not be done. If path is NULL a socket path
+  check will not be done. For normal AF_UNIX sockets set length to
+  0. For abstract namespace sockets set length to the length of the
+  socket name (including the initial 0 byte), and pass the full
+  socket path in path (including the initial 0 byte). The listening
+  flag is used the same way as in sd_is_socket(). Returns a negative
+  errno style error code on failure.
+
+  See sd_is_socket_unix(3) for more information.
+*/
+int netsnmp_sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);
+
+/*
+  Informs systemd about changed daemon state. This takes a number of
+  newline separated environment-style variable assignments in a
+  string. The following variables are known:
+
+     READY=1      Tells systemd that daemon startup is finished (only
+                  relevant for services of Type=notify). The passed
+                  argument is a boolean "1" or "0". Since there is
+                  little value in signaling non-readiness the only
+                  value daemons should send is "READY=1".
+
+     STATUS=...   Passes a single-line status string back to systemd
+                  that describes the daemon state. This is free-from
+                  and can be used for various purposes: general state
+                  feedback, fsck-like programs could pass completion
+                  percentages and failing programs could pass a human
+                  readable error message. Example: "STATUS=Completed
+                  66% of file system check..."
+
+     ERRNO=...    If a daemon fails, the errno-style error code,
+                  formatted as string. Example: "ERRNO=2" for ENOENT.
+
+     BUSERROR=... If a daemon fails, the D-Bus error-style error
+                  code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
+
+     MAINPID=...  The main pid of a daemon, in case systemd did not
+                  fork off the process itself. Example: "MAINPID=4711"
+
+  Daemons can choose to send additional variables. However, it is
+  recommended to prefix variable names not listed above with X_.
+
+  Returns a negative errno-style error code on failure. Returns > 0
+  if systemd could be notified, 0 if it couldn't possibly because
+  systemd is not running.
+
+  Example: When a daemon finished starting up, it could issue this
+  call to notify systemd about it:
+
+     sd_notify(0, "READY=1");
+
+  See sd_notifyf() for more complete examples.
+
+  See sd_notify(3) for more information.
+*/
+int netsnmp_sd_notify(int unset_environment, const char *state);
+
+/*
+  Similar to sd_notify() but takes a format string.
+
+  Example 1: A daemon could send the following after initialization:
+
+     sd_notifyf(0, "READY=1\n"
+                   "STATUS=Processing requests...\n"
+                   "MAINPID=%lu",
+                   (unsigned long) getpid());
+
+  Example 2: A daemon could send the following shortly before
+  exiting, on failure:
+
+     sd_notifyf(0, "STATUS=Failed to start up: %s\n"
+                   "ERRNO=%i",
+                   strerror(errno),
+                   errno);
+
+  See sd_notifyf(3) for more information.
+*/
+int netsnmp_sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_attr_(2,3);
+
+/*
+  Returns > 0 if the system was booted with systemd. Returns < 0 on
+  error. Returns 0 if the system was not booted with systemd. Note
+  that all of the functions above handle non-systemd boots just
+  fine. You should NOT protect them with a call to this function. Also
+  note that this function checks whether the system, not the user
+  session is controlled by systemd. However the functions above work
+  for both user and system services.
+
+  See sd_booted(3) for more information.
+*/
+int netsnmp_sd_booted(void);
+
+/**
+ * Find an socket with given parameters. See man sd_is_socket_inet for
+ * description of the arguments.
+ *
+ * Returns the file descriptor if it is found, 0 otherwise.
+ */
+int netsnmp_sd_find_inet_socket(int family, int type, int listening, int port);
+
+/**
+ * Find an unix socket with given parameters. See man sd_is_socket_unix for
+ * description of the arguments.
+ *
+ * Returns the file descriptor if it is found, 0 otherwise.
+ */
+int
+netsnmp_sd_find_unix_socket(int type, int listening, const char *path);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* SNMPD_SD_DAEMON_H */
diff --git a/snmplib/sd-daemon.c b/snmplib/sd-daemon.c
new file mode 100644
index 0000000..42dba29
--- /dev/null
+++ b/snmplib/sd-daemon.c
@@ -0,0 +1,532 @@
+/*
+ * Systemd integration parts.
+ *
+ * Most of this file is directly copied from systemd sources.
+ * Changes:
+ * - all functions were renamed to have netsnmp_ prefix
+ * - includes were  changed to match Net-SNMP style.
+ * - removed gcc export macros
+ * - removed POSIX message queues
+ */
+
+#include <net-snmp/net-snmp-config.h>
+#include <net-snmp/net-snmp-features.h>
+#include <net-snmp/types.h>
+#include <net-snmp/library/snmp_debug.h>
+
+#ifndef NETSNMP_NO_SYSTEMD
+
+/***
+  Copyright 2010 Lennart Poettering
+
+  Permission is hereby granted, free of charge, to any person
+  obtaining a copy of this software and associated documentation files
+  (the "Software"), to deal in the Software without restriction,
+  including without limitation the rights to use, copy, modify, merge,
+  publish, distribute, sublicense, and/or sell copies of the Software,
+  and to permit persons to whom the Software is furnished to do so,
+  subject to the following conditions:
+
+  The above copyright notice and this permission notice shall be
+  included in all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+  SOFTWARE.
+***/
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/fcntl.h>
+#include <netinet/in.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <limits.h>
+
+#include <net-snmp/library/sd-daemon.h>
+
+int netsnmp_sd_listen_fds(int unset_environment) {
+
+        int r, fd;
+        const char *e;
+        char *p = NULL;
+        unsigned long l;
+
+        if (!(e = getenv("LISTEN_PID"))) {
+                r = 0;
+                goto finish;
+        }
+
+        errno = 0;
+        l = strtoul(e, &p, 10);
+
+        if (errno != 0) {
+                r = -errno;
+                goto finish;
+        }
+
+        if (!p || *p || l <= 0) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        /* Is this for us? */
+        if (getpid() != (pid_t) l) {
+                r = 0;
+                goto finish;
+        }
+
+        if (!(e = getenv("LISTEN_FDS"))) {
+                r = 0;
+                goto finish;
+        }
+
+        errno = 0;
+        l = strtoul(e, &p, 10);
+
+        if (errno != 0) {
+                r = -errno;
+                goto finish;
+        }
+
+        if (!p || *p) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + (int) l; fd ++) {
+                int flags;
+
+                if ((flags = fcntl(fd, F_GETFD)) < 0) {
+                        r = -errno;
+                        goto finish;
+                }
+
+                if (flags & FD_CLOEXEC)
+                        continue;
+
+                if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) < 0) {
+                        r = -errno;
+                        goto finish;
+                }
+        }
+
+        r = (int) l;
+
+finish:
+        if (unset_environment) {
+                unsetenv("LISTEN_PID");
+                unsetenv("LISTEN_FDS");
+        }
+
+        return r;
+}
+
+int netsnmp_sd_is_fifo(int fd, const char *path) {
+        struct stat st_fd;
+
+        if (fd < 0)
+                return -EINVAL;
+
+        memset(&st_fd, 0, sizeof(st_fd));
+        if (fstat(fd, &st_fd) < 0)
+                return -errno;
+
+        if (!S_ISFIFO(st_fd.st_mode))
+                return 0;
+
+        if (path) {
+                struct stat st_path;
+
+                memset(&st_path, 0, sizeof(st_path));
+                if (stat(path, &st_path) < 0) {
+
+                        if (errno == ENOENT || errno == ENOTDIR)
+                                return 0;
+
+                        return -errno;
+                }
+
+                return
+                        st_path.st_dev == st_fd.st_dev &&
+                        st_path.st_ino == st_fd.st_ino;
+        }
+
+        return 1;
+}
+
+int netsnmp_sd_is_special(int fd, const char *path) {
+        struct stat st_fd;
+
+        if (fd < 0)
+                return -EINVAL;
+
+        if (fstat(fd, &st_fd) < 0)
+                return -errno;
+
+        if (!S_ISREG(st_fd.st_mode) && !S_ISCHR(st_fd.st_mode))
+                return 0;
+
+        if (path) {
+                struct stat st_path;
+
+                if (stat(path, &st_path) < 0) {
+
+                        if (errno == ENOENT || errno == ENOTDIR)
+                                return 0;
+
+                        return -errno;
+                }
+
+                if (S_ISREG(st_fd.st_mode) && S_ISREG(st_path.st_mode))
+                        return
+                                st_path.st_dev == st_fd.st_dev &&
+                                st_path.st_ino == st_fd.st_ino;
+                else if (S_ISCHR(st_fd.st_mode) && S_ISCHR(st_path.st_mode))
+                        return st_path.st_rdev == st_fd.st_rdev;
+                else
+                        return 0;
+        }
+
+        return 1;
+}
+
+static int sd_is_socket_internal(int fd, int type, int listening) {
+        struct stat st_fd;
+
+        if (fd < 0 || type < 0)
+                return -EINVAL;
+
+        if (fstat(fd, &st_fd) < 0)
+                return -errno;
+
+        if (!S_ISSOCK(st_fd.st_mode))
+                return 0;
+
+        if (type != 0) {
+                int other_type = 0;
+                socklen_t l = sizeof(other_type);
+
+                if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &other_type, &l) < 0)
+                        return -errno;
+
+                if (l != sizeof(other_type))
+                        return -EINVAL;
+
+                if (other_type != type)
+                        return 0;
+        }
+
+        if (listening >= 0) {
+                int accepting = 0;
+                socklen_t l = sizeof(accepting);
+
+                if (getsockopt(fd, SOL_SOCKET, SO_ACCEPTCONN, &accepting, &l) < 0)
+                        return -errno;
+
+                if (l != sizeof(accepting))
+                        return -EINVAL;
+
+                if (!accepting != !listening)
+                        return 0;
+        }
+
+        return 1;
+}
+
+union sockaddr_union {
+        struct sockaddr sa;
+        struct sockaddr_in in4;
+        struct sockaddr_in6 in6;
+        struct sockaddr_un un;
+        struct sockaddr_storage storage;
+};
+
+int netsnmp_sd_is_socket(int fd, int family, int type, int listening) {
+        int r;
+
+        if (family < 0)
+                return -EINVAL;
+
+        if ((r = sd_is_socket_internal(fd, type, listening)) <= 0)
+                return r;
+
+        if (family > 0) {
+                union sockaddr_union sockaddr;
+                socklen_t l;
+
+                memset(&sockaddr, 0, sizeof(sockaddr));
+                l = sizeof(sockaddr);
+
+                if (getsockname(fd, &sockaddr.sa, &l) < 0)
+                        return -errno;
+
+                if (l < sizeof(sa_family_t))
+                        return -EINVAL;
+
+                return sockaddr.sa.sa_family == family;
+        }
+
+        return 1;
+}
+
+int netsnmp_sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port) {
+        union sockaddr_union sockaddr;
+        socklen_t l;
+        int r;
+
+        if (family != 0 && family != AF_INET && family != AF_INET6)
+                return -EINVAL;
+
+        if ((r = sd_is_socket_internal(fd, type, listening)) <= 0)
+                return r;
+
+        memset(&sockaddr, 0, sizeof(sockaddr));
+        l = sizeof(sockaddr);
+
+        if (getsockname(fd, &sockaddr.sa, &l) < 0)
+                return -errno;
+
+        if (l < sizeof(sa_family_t))
+                return -EINVAL;
+
+        if (sockaddr.sa.sa_family != AF_INET &&
+            sockaddr.sa.sa_family != AF_INET6)
+                return 0;
+
+        if (family > 0)
+                if (sockaddr.sa.sa_family != family)
+                        return 0;
+
+        if (port > 0) {
+                if (sockaddr.sa.sa_family == AF_INET) {
+                        if (l < sizeof(struct sockaddr_in))
+                                return -EINVAL;
+
+                        return htons(port) == sockaddr.in4.sin_port;
+                } else {
+                        if (l < sizeof(struct sockaddr_in6))
+                                return -EINVAL;
+
+                        return htons(port) == sockaddr.in6.sin6_port;
+                }
+        }
+
+        return 1;
+}
+
+int netsnmp_sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length) {
+        union sockaddr_union sockaddr;
+        socklen_t l;
+        int r;
+
+        if ((r = sd_is_socket_internal(fd, type, listening)) <= 0)
+                return r;
+
+        memset(&sockaddr, 0, sizeof(sockaddr));
+        l = sizeof(sockaddr);
+
+        if (getsockname(fd, &sockaddr.sa, &l) < 0)
+                return -errno;
+
+        if (l < sizeof(sa_family_t))
+                return -EINVAL;
+
+        if (sockaddr.sa.sa_family != AF_UNIX)
+                return 0;
+
+        if (path) {
+                if (length <= 0)
+                        length = strlen(path);
+
+                if (length <= 0)
+                        /* Unnamed socket */
+                        return l == offsetof(struct sockaddr_un, sun_path);
+
+                if (path[0])
+                        /* Normal path socket */
+                        return
+                                (l >= offsetof(struct sockaddr_un, sun_path) + length + 1) &&
+                                memcmp(path, sockaddr.un.sun_path, length+1) == 0;
+                else
+                        /* Abstract namespace socket */
+                        return
+                                (l == offsetof(struct sockaddr_un, sun_path) + length) &&
+                                memcmp(path, sockaddr.un.sun_path, length) == 0;
+        }
+
+        return 1;
+}
+
+int netsnmp_sd_notify(int unset_environment, const char *state) {
+        int fd = -1, r;
+        struct msghdr msghdr;
+        struct iovec iovec;
+        union sockaddr_union sockaddr;
+        const char *e;
+
+        if (!state) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        if (!(e = getenv("NOTIFY_SOCKET")))
+                return 0;
+
+        /* Must be an abstract socket, or an absolute path */
+        if ((e[0] != '@' && e[0] != '/') || e[1] == 0) {
+                r = -EINVAL;
+                goto finish;
+        }
+
+        if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
+                r = -errno;
+                goto finish;
+        }
+
+        memset(&sockaddr, 0, sizeof(sockaddr));
+        sockaddr.sa.sa_family = AF_UNIX;
+        strncpy(sockaddr.un.sun_path, e, sizeof(sockaddr.un.sun_path));
+
+        if (sockaddr.un.sun_path[0] == '@')
+                sockaddr.un.sun_path[0] = 0;
+
+        memset(&iovec, 0, sizeof(iovec));
+        iovec.iov_base = (char *)state;
+        iovec.iov_len = strlen(state);
+
+        memset(&msghdr, 0, sizeof(msghdr));
+        msghdr.msg_name = &sockaddr;
+        msghdr.msg_namelen = offsetof(struct sockaddr_un, sun_path) + strlen(e);
+
+        if (msghdr.msg_namelen > sizeof(struct sockaddr_un))
+                msghdr.msg_namelen = sizeof(struct sockaddr_un);
+
+        msghdr.msg_iov = &iovec;
+        msghdr.msg_iovlen = 1;
+
+        if (sendmsg(fd, &msghdr, MSG_NOSIGNAL) < 0) {
+                r = -errno;
+                goto finish;
+        }
+
+        r = 1;
+
+finish:
+        if (unset_environment)
+                unsetenv("NOTIFY_SOCKET");
+
+        if (fd >= 0)
+                close(fd);
+
+        return r;
+}
+
+int netsnmp_sd_notifyf(int unset_environment, const char *format, ...) {
+        va_list ap;
+        char *p = NULL;
+        int r;
+
+        va_start(ap, format);
+        r = vasprintf(&p, format, ap);
+        va_end(ap);
+
+        if (r < 0 || !p)
+                return -ENOMEM;
+
+        r = netsnmp_sd_notify(unset_environment, p);
+        free(p);
+
+        return r;
+}
+
+int netsnmp_sd_booted(void) {
+        struct stat a, b;
+
+        /* We simply test whether the systemd cgroup hierarchy is
+         * mounted */
+
+        if (lstat("/sys/fs/cgroup", &a) < 0)
+                return 0;
+
+        if (lstat("/sys/fs/cgroup/systemd", &b) < 0)
+                return 0;
+
+        return a.st_dev != b.st_dev;
+}
+
+/* End of original sd-daemon.c from systemd sources */
+
+int
+netsnmp_sd_find_inet_socket(int family, int type, int listening, int port)
+{
+    int count, fd;
+
+    count = netsnmp_sd_listen_fds(0);
+    if (count <= 0) {
+        DEBUGMSGTL(("systemd:find_inet_socket", "No LISTEN_FDS found.\n"));
+        return 0;
+    }
+    DEBUGMSGTL(("systemd:find_inet_socket", "LISTEN_FDS reports %d sockets.\n",
+            count));
+
+    for (fd = 3; fd < 3+count; fd++) {
+        int rc = netsnmp_sd_is_socket_inet(fd, family, type, listening, port);
+        if (rc < 0)
+            DEBUGMSGTL(("systemd:find_inet_socket",
+                    "sd_is_socket_inet error: %d\n", rc));
+        if (rc > 0) {
+            DEBUGMSGTL(("systemd:find_inet_socket",
+                    "Found the socket in LISTEN_FDS\n"));
+            return fd;
+        }
+    }
+    DEBUGMSGTL(("systemd:find_inet_socket", "Socket not found in LISTEN_FDS\n"));
+    return 0;
+}
+
+int
+netsnmp_sd_find_unix_socket(int type, int listening, const char *path)
+{
+    int count, fd;
+
+    count = netsnmp_sd_listen_fds(0);
+    if (count <= 0) {
+        DEBUGMSGTL(("systemd:find_unix_socket", "No LISTEN_FDS found.\n"));
+        return 0;
+    }
+    DEBUGMSGTL(("systemd:find_unix_socket", "LISTEN_FDS reports %d sockets.\n",
+            count));
+
+    for (fd = 3; fd < 3+count; fd++) {
+        int rc = netsnmp_sd_is_socket_unix(fd, type, listening, path, 0);
+        if (rc < 0)
+            DEBUGMSGTL(("systemd:find_unix_socket",
+                    "netsnmp_sd_is_socket_unix error: %d\n", rc));
+        if (rc > 0) {
+            DEBUGMSGTL(("systemd:find_unix_socket",
+                    "Found the socket in LISTEN_FDS\n"));
+            return fd;
+        }
+    }
+    DEBUGMSGTL(("systemd:find_unix_socket", "Socket not found in LISTEN_FDS\n"));
+    return 0;
+}
+
+#endif /* ! NETSNMP_NO_SYSTEMD */
diff --git a/snmplib/transports/snmpTCPDomain.c b/snmplib/transports/snmpTCPDomain.c
index b8bdba4..ab7f3a1 100644
--- a/snmplib/transports/snmpTCPDomain.c
+++ b/snmplib/transports/snmpTCPDomain.c
@@ -43,6 +43,10 @@
 #include <net-snmp/library/snmpTCPBaseDomain.h>
 #include <net-snmp/library/tools.h>
 
+#ifndef NETSNMP_NO_SYSTEMD
+#include <net-snmp/library/sd-daemon.h>
+#endif
+
 /*
  * needs to be in sync with the definitions in snmplib/snmpUDPDomain.c
  * and perl/agent/agent.xs
@@ -149,6 +153,7 @@ netsnmp_tcp_transport(struct sockaddr_in *addr, int local)
     netsnmp_transport *t = NULL;
     netsnmp_udp_addr_pair *addr_pair = NULL;
     int rc = 0;
+    int socket_initialized = 0;
 
 #ifdef NETSNMP_NO_LISTEN_SUPPORT
     if (local)
@@ -178,7 +183,19 @@ netsnmp_tcp_transport(struct sockaddr_in *addr, int local)
     t->domain_length =
         sizeof(netsnmp_snmpTCPDomain) / sizeof(netsnmp_snmpTCPDomain[0]);
 
-    t->sock = socket(PF_INET, SOCK_STREAM, 0);
+#ifndef NETSNMP_NO_SYSTEMD
+    /*
+     * Maybe the socket was already provided by systemd...
+     */
+    if (local) {
+        t->sock = netsnmp_sd_find_inet_socket(PF_INET, SOCK_STREAM, 1,
+                ntohs(addr->sin_port));
+        if (t->sock)
+            socket_initialized = 1;
+    }
+#endif
+    if (!socket_initialized)
+        t->sock = socket(PF_INET, SOCK_STREAM, 0);
     if (t->sock < 0) {
         netsnmp_transport_free(t);
         return NULL;
@@ -215,11 +232,13 @@ netsnmp_tcp_transport(struct sockaddr_in *addr, int local)
         setsockopt(t->sock, SOL_SOCKET, SO_REUSEADDR, (void *)&opt,
 		   sizeof(opt));
 
-        rc = bind(t->sock, (struct sockaddr *)addr, sizeof(struct sockaddr));
-        if (rc != 0) {
-            netsnmp_socketbase_close(t);
-            netsnmp_transport_free(t);
-            return NULL;
+        if (!socket_initialized) {
+            rc = bind(t->sock, (struct sockaddr *)addr, sizeof(struct sockaddr));
+            if (rc != 0) {
+                netsnmp_socketbase_close(t);
+                netsnmp_transport_free(t);
+                return NULL;
+            }
         }
 
         /*
@@ -235,12 +254,13 @@ netsnmp_tcp_transport(struct sockaddr_in *addr, int local)
         /*
          * Now sit here and wait for connections to arrive.  
          */
-
-        rc = listen(t->sock, NETSNMP_STREAM_QUEUE_LEN);
-        if (rc != 0) {
-            netsnmp_socketbase_close(t);
-            netsnmp_transport_free(t);
-            return NULL;
+        if (!socket_initialized) {
+            rc = listen(t->sock, NETSNMP_STREAM_QUEUE_LEN);
+            if (rc != 0) {
+                netsnmp_socketbase_close(t);
+                netsnmp_transport_free(t);
+                return NULL;
+            }
         }
         
         /*
diff --git a/snmplib/transports/snmpTCPIPv6Domain.c b/snmplib/transports/snmpTCPIPv6Domain.c
index 3c96856..305a861 100644
--- a/snmplib/transports/snmpTCPIPv6Domain.c
+++ b/snmplib/transports/snmpTCPIPv6Domain.c
@@ -49,6 +49,10 @@
 #include <net-snmp/library/snmpTCPBaseDomain.h>
 #include <net-snmp/library/tools.h>
 
+#ifndef NETSNMP_NO_SYSTEMD
+#include <net-snmp/library/sd-daemon.h>
+#endif
+
 #include "inet_ntop.h"
 
 oid netsnmp_TCPIPv6Domain[] = { TRANSPORT_DOMAIN_TCP_IPV6 };
@@ -140,6 +144,8 @@ netsnmp_tcp6_transport(struct sockaddr_in6 *addr, int local)
 {
     netsnmp_transport *t = NULL;
     int             rc = 0;
+    char           *str = NULL;
+    int             socket_initialized = 0;
 
 #ifdef NETSNMP_NO_LISTEN_SUPPORT
     if (local)
@@ -174,7 +180,19 @@ netsnmp_tcp6_transport(struct sockaddr_in6 *addr, int local)
     t->domain = netsnmp_TCPIPv6Domain;
     t->domain_length = sizeof(netsnmp_TCPIPv6Domain) / sizeof(oid);
 
-    t->sock = socket(PF_INET6, SOCK_STREAM, 0);
+#ifndef NETSNMP_NO_SYSTEMD
+    /*
+     * Maybe the socket was already provided by systemd...
+     */
+    if (local) {
+        t->sock = netsnmp_sd_find_inet_socket(PF_INET6, SOCK_STREAM, 1,
+                ntohs(addr->sin6_port));
+        if (t->sock)
+            socket_initialized = 1;
+    }
+#endif
+    if (!socket_initialized)
+        t->sock = socket(PF_INET6, SOCK_STREAM, 0);
     if (t->sock < 0) {
         netsnmp_transport_free(t);
         return NULL;
@@ -220,12 +238,14 @@ netsnmp_tcp6_transport(struct sockaddr_in6 *addr, int local)
 
         setsockopt(t->sock, SOL_SOCKET, SO_REUSEADDR, (void *)&opt, sizeof(opt));
 
-        rc = bind(t->sock, (struct sockaddr *) addr,
-		  sizeof(struct sockaddr_in6));
-        if (rc != 0) {
-            netsnmp_socketbase_close(t);
-            netsnmp_transport_free(t);
-            return NULL;
+        if (!socket_initialized) {
+            rc = bind(t->sock, (struct sockaddr *) addr,
+                    sizeof(struct sockaddr_in6));
+            if (rc != 0) {
+                netsnmp_socketbase_close(t);
+                netsnmp_transport_free(t);
+                return NULL;
+            }
         }
 
         /*
@@ -242,11 +262,13 @@ netsnmp_tcp6_transport(struct sockaddr_in6 *addr, int local)
          * Now sit here and wait for connections to arrive.  
          */
 
-        rc = listen(t->sock, NETSNMP_STREAM_QUEUE_LEN);
-        if (rc != 0) {
-            netsnmp_socketbase_close(t);
-            netsnmp_transport_free(t);
-            return NULL;
+        if (!socket_initialized) {
+            rc = listen(t->sock, NETSNMP_STREAM_QUEUE_LEN);
+            if (rc != 0) {
+                netsnmp_socketbase_close(t);
+                netsnmp_transport_free(t);
+                return NULL;
+            }
         }
         
         /*
diff --git a/snmplib/transports/snmpUDPIPv4BaseDomain.c b/snmplib/transports/snmpUDPIPv4BaseDomain.c
index c67427b..428e6d6 100644
--- a/snmplib/transports/snmpUDPIPv4BaseDomain.c
+++ b/snmplib/transports/snmpUDPIPv4BaseDomain.c
@@ -40,6 +40,10 @@
 
 #include <net-snmp/library/snmpSocketBaseDomain.h>
 
+#ifndef NETSNMP_NO_SYSTEMD
+#include <net-snmp/library/sd-daemon.h>
+#endif
+
 #if (defined(linux) && defined(IP_PKTINFO)) \
     || defined(IP_RECVDSTADDR) && HAVE_STRUCT_MSGHDR_MSG_CONTROL \
                                && HAVE_STRUCT_MSGHDR_MSG_FLAGS
@@ -67,6 +71,7 @@ netsnmp_udpipv4base_transport(struct sockaddr_in *addr, int local)
     char           *client_socket = NULL;
     netsnmp_indexed_addr_pair addr_pair;
     socklen_t       local_addr_len;
+    int             socket_initialized = 0;
 
 #ifdef NETSNMP_NO_LISTEN_SUPPORT
     if (local)
@@ -91,7 +96,19 @@ netsnmp_udpipv4base_transport(struct sockaddr_in *addr, int local)
         free(str);
     }
 
-    t->sock = socket(PF_INET, SOCK_DGRAM, 0);
+#ifndef NETSNMP_NO_SYSTEMD
+    /*
+     * Maybe the socket was already provided by systemd...
+     */
+    if (local) {
+        t->sock = netsnmp_sd_find_inet_socket(PF_INET, SOCK_DGRAM, -1,
+                ntohs(addr->sin_port));
+        if (t->sock)
+            socket_initialized = 1;
+    }
+#endif
+    if (!socket_initialized)
+        t->sock = socket(PF_INET, SOCK_DGRAM, 0);
     DEBUGMSGTL(("UDPBase", "openned socket %d as local=%d\n", t->sock, local)); 
     if (t->sock < 0) {
         netsnmp_transport_free(t);
@@ -141,12 +158,14 @@ netsnmp_udpipv4base_transport(struct sockaddr_in *addr, int local)
             DEBUGMSGTL(("netsnmp_udp", "set IP_RECVDSTADDR\n"));
         }
 #endif
-        rc = bind(t->sock, (struct sockaddr *) addr,
-                  sizeof(struct sockaddr));
-        if (rc != 0) {
-            netsnmp_socketbase_close(t);
-            netsnmp_transport_free(t);
-            return NULL;
+        if (!socket_initialized) {
+            rc = bind(t->sock, (struct sockaddr *) addr,
+                    sizeof(struct sockaddr));
+            if (rc != 0) {
+                netsnmp_socketbase_close(t);
+                netsnmp_transport_free(t);
+                return NULL;
+            }
         }
         t->data = NULL;
         t->data_length = 0;
diff --git a/snmplib/transports/snmpUDPIPv6Domain.c b/snmplib/transports/snmpUDPIPv6Domain.c
index b3eaae4..35b617f 100644
--- a/snmplib/transports/snmpUDPIPv6Domain.c
+++ b/snmplib/transports/snmpUDPIPv6Domain.c
@@ -67,6 +67,10 @@ static const struct in6_addr in6addr_any = IN6ADDR_ANY_INIT;
 #include <net-snmp/library/snmpSocketBaseDomain.h>
 #include <net-snmp/library/tools.h>
 
+#ifndef NETSNMP_NO_SYSTEMD
+#include <net-snmp/library/sd-daemon.h>
+#endif
+
 #include "inet_ntop.h"
 #include "inet_pton.h"
 
@@ -190,6 +194,8 @@ netsnmp_udp6_transport(struct sockaddr_in6 *addr, int local)
 {
     netsnmp_transport *t = NULL;
     int             rc = 0;
+    char           *str = NULL;
+    int             socket_initialized = 0;
 
 #ifdef NETSNMP_NO_LISTEN_SUPPORT
     if (local)
@@ -217,7 +223,19 @@ netsnmp_udp6_transport(struct sockaddr_in6 *addr, int local)
     t->domain_length =
         sizeof(netsnmp_UDPIPv6Domain) / sizeof(netsnmp_UDPIPv6Domain[0]);
 
-    t->sock = socket(PF_INET6, SOCK_DGRAM, 0);
+#ifndef NETSNMP_NO_SYSTEMD
+    /*
+     * Maybe the socket was already provided by systemd...
+     */
+    if (local) {
+        t->sock = netsnmp_sd_find_inet_socket(PF_INET6, SOCK_DGRAM, -1,
+                ntohs(addr->sin6_port));
+        if (t->sock)
+            socket_initialized = 1;
+    }
+#endif
+    if (!socket_initialized)
+        t->sock = socket(PF_INET6, SOCK_DGRAM, 0);
     if (t->sock < 0) {
         netsnmp_transport_free(t);
         return NULL;
@@ -242,13 +260,14 @@ netsnmp_udp6_transport(struct sockaddr_in6 *addr, int local)
 	  } 
 	}
 #endif
-
-        rc = bind(t->sock, (struct sockaddr *) addr,
-		  sizeof(struct sockaddr_in6));
-        if (rc != 0) {
-            netsnmp_socketbase_close(t);
-            netsnmp_transport_free(t);
-            return NULL;
+        if (!socket_initialized) {
+            rc = bind(t->sock, (struct sockaddr *) addr,
+                    sizeof(struct sockaddr_in6));
+            if (rc != 0) {
+                netsnmp_socketbase_close(t);
+                netsnmp_transport_free(t);
+                return NULL;
+            }
         }
         t->local = (unsigned char*)malloc(18);
         if (t->local == NULL) {
diff --git a/snmplib/transports/snmpUnixDomain.c b/snmplib/transports/snmpUnixDomain.c
index 674dc2b..9f3d3cb 100644
--- a/snmplib/transports/snmpUnixDomain.c
+++ b/snmplib/transports/snmpUnixDomain.c
@@ -37,6 +37,10 @@
 #include <net-snmp/library/system.h> /* mkdirhier */
 #include <net-snmp/library/tools.h>
 
+#ifndef NETSNMP_NO_SYSTEMD
+#include <net-snmp/library/sd-daemon.h>
+#endif
+
 netsnmp_feature_child_of(transport_unix_socket_all, transport_all)
 netsnmp_feature_child_of(unix_socket_paths, transport_unix_socket_all)
 
@@ -295,6 +299,8 @@ netsnmp_unix_transport(struct sockaddr_un *addr, int local)
     netsnmp_transport *t = NULL;
     sockaddr_un_pair *sup = NULL;
     int             rc = 0;
+    char           *string = NULL;
+    int             socket_initialized = 0;
 
 #ifdef NETSNMP_NO_LISTEN_SUPPORT
     /* SPECIAL CIRCUMSTANCE: We still want AgentX to be able to operate,
@@ -333,7 +339,18 @@ netsnmp_unix_transport(struct sockaddr_un *addr, int local)
     t->data_length = sizeof(sockaddr_un_pair);
     sup = (sockaddr_un_pair *) t->data;
 
-    t->sock = socket(PF_UNIX, SOCK_STREAM, 0);
+#ifndef NETSNMP_NO_SYSTEMD
+    /*
+     * Maybe the socket was already provided by systemd...
+     */
+    if (local) {
+        t->sock = netsnmp_sd_find_unix_socket(SOCK_STREAM, 1, addr->sun_path);
+        if (t->sock)
+            socket_initialized = 1;
+    }
+#endif
+    if (!socket_initialized)
+        t->sock = socket(PF_UNIX, SOCK_STREAM, 0);
     if (t->sock < 0) {
         netsnmp_transport_free(t);
         return NULL;
@@ -357,25 +374,26 @@ netsnmp_unix_transport(struct sockaddr_un *addr, int local)
 
         t->flags |= NETSNMP_TRANSPORT_FLAG_LISTEN;
 
-        unlink(addr->sun_path);
-        rc = bind(t->sock, (struct sockaddr *) addr, SUN_LEN(addr));
-
-        if (rc != 0 && errno == ENOENT && create_path) {
-            rc = mkdirhier(addr->sun_path, create_mode, 1);
+        if (!socket_initialized) {
+            unlink(addr->sun_path);
+            rc = bind(t->sock, (struct sockaddr *) addr, SUN_LEN(addr));
+            if (rc != 0 && errno == ENOENT && create_path) {
+                rc = mkdirhier(addr->sun_path, create_mode, 1);
+                if (rc != 0) {
+                    netsnmp_unix_close(t);
+                    netsnmp_transport_free(t);
+                    return NULL;
+                }
+                rc = bind(t->sock, (struct sockaddr *) addr, SUN_LEN(addr));
+            }
             if (rc != 0) {
+                DEBUGMSGTL(("netsnmp_unix_transport",
+                        "couldn't bind \"%s\", errno %d (%s)\n",
+                        addr->sun_path, errno, strerror(errno)));
                 netsnmp_unix_close(t);
                 netsnmp_transport_free(t);
                 return NULL;
             }
-            rc = bind(t->sock, (struct sockaddr *) addr, SUN_LEN(addr));
-        }
-        if (rc != 0) {
-            DEBUGMSGTL(("netsnmp_unix_transport",
-                        "couldn't bind \"%s\", errno %d (%s)\n",
-                        addr->sun_path, errno, strerror(errno)));
-            netsnmp_unix_close(t);
-            netsnmp_transport_free(t);
-            return NULL;
         }
 
         /*
@@ -391,16 +409,17 @@ netsnmp_unix_transport(struct sockaddr_un *addr, int local)
          * Now sit here and listen for connections to arrive.
          */
 
-        rc = listen(t->sock, NETSNMP_STREAM_QUEUE_LEN);
-        if (rc != 0) {
-            DEBUGMSGTL(("netsnmp_unix_transport",
-                        "couldn't listen to \"%s\", errno %d (%s)\n",
-                        addr->sun_path, errno, strerror(errno)));
-            netsnmp_unix_close(t);
-            netsnmp_transport_free(t);
-            return NULL;
+        if (!socket_initialized) {
+            rc = listen(t->sock, NETSNMP_STREAM_QUEUE_LEN);
+            if (rc != 0) {
+                DEBUGMSGTL(("netsnmp_unix_transport",
+                            "couldn't listen to \"%s\", errno %d (%s)\n",
+                            addr->sun_path, errno, strerror(errno)));
+                netsnmp_unix_close(t);
+                netsnmp_transport_free(t);
+                return NULL;
+            }
         }
-
     } else {
         t->remote = (u_char *)malloc(strlen(addr->sun_path));
         if (t->remote == NULL) {
diff --git a/win32/libsnmp/Makefile.in b/win32/libsnmp/Makefile.in
index 98d83c8..dd5689b 100644
--- a/win32/libsnmp/Makefile.in
+++ b/win32/libsnmp/Makefile.in
@@ -42,6 +42,7 @@ LIB32_OBJS= \
 	"$(INTDIR)\read_config.obj" \
 	"$(INTDIR)\readdir.obj" \
 	"$(INTDIR)\scapi.obj" \
+	"$(INTDIR)\sd-daemon.obj" \
 	"$(INTDIR)\snmp-tc.obj" \
 	"$(INTDIR)\snmp.obj" \
 	"$(INTDIR)\snmpCallbackDomain.obj" \
@@ -307,6 +308,12 @@ SOURCE=..\..\snmplib\scapi.c
 	$(CPP) $(CPP_PROJ) $(SOURCE)
 
 
+SOURCE=..\..\snmplib\sd-daemon.c
+
+"$(INTDIR)\sd-daemon.obj" : $(SOURCE) "$(INTDIR)"
+	$(CPP) $(CPP_PROJ) $(SOURCE)
+
+
 SOURCE="..\..\snmplib\snmp-tc.c"
 
 "$(INTDIR)\snmp-tc.obj" : $(SOURCE) "$(INTDIR)"
diff --git a/win32/net-snmp/net-snmp-config.h b/win32/net-snmp/net-snmp-config.h
index 7791ee0..1eccf42 100644
--- a/win32/net-snmp/net-snmp-config.h
+++ b/win32/net-snmp/net-snmp-config.h
@@ -1705,6 +1705,8 @@ enum {
 #define DMALLOC_FUNC_CHECK
 #endif
 
+#define NETSNMP_NO_SYSTEMD
+
 /* #undef NETSNMP_ENABLE_LOCAL_SMUX */
 
 /* define if agentx transport is to use domain sockets only */
diff --git a/win32/net-snmp/net-snmp-config.h.in b/win32/net-snmp/net-snmp-config.h.in
index 5215865..1607bfa 100644
--- a/win32/net-snmp/net-snmp-config.h.in
+++ b/win32/net-snmp/net-snmp-config.h.in
@@ -1705,6 +1705,8 @@ enum {
 #define DMALLOC_FUNC_CHECK
 #endif
 
+#define NETSNMP_NO_SYSTEMD
+
 /* #undef NETSNMP_ENABLE_LOCAL_SMUX */
 
 /* define if agentx transport is to use domain sockets only */
