Adding upstream version 252.22.upstream/252.22

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3544 insertions, 0 deletions

diff --git a/src/core/socket.c b/src/core/socket.c
new file mode 100644
index 0000000..e86e9c8
--- /dev/null
+++ b/src/core/socket.c
@@ -0,0 +1,3544 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <mqueue.h>
+#include <netinet/tcp.h>
+#include <sys/epoll.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <linux/sctp.h>
+
+#include "alloc-util.h"
+#include "bpf-firewall.h"
+#include "bus-error.h"
+#include "bus-util.h"
+#include "chase-symlinks.h"
+#include "copy.h"
+#include "dbus-socket.h"
+#include "dbus-unit.h"
+#include "def.h"
+#include "errno-list.h"
+#include "exit-status.h"
+#include "fd-util.h"
+#include "format-util.h"
+#include "in-addr-util.h"
+#include "io-util.h"
+#include "ip-protocol-list.h"
+#include "label.h"
+#include "log.h"
+#include "mkdir-label.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "selinux-util.h"
+#include "serialize.h"
+#include "service.h"
+#include "signal-util.h"
+#include "smack-util.h"
+#include "socket.h"
+#include "socket-netlink.h"
+#include "special.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "strv.h"
+#include "unit-name.h"
+#include "unit.h"
+#include "user-util.h"
+
+struct SocketPeer {
+        unsigned n_ref;
+
+        Socket *socket;
+        union sockaddr_union peer;
+        socklen_t peer_salen;
+};
+
+static const UnitActiveState state_translation_table[_SOCKET_STATE_MAX] = {
+        [SOCKET_DEAD] = UNIT_INACTIVE,
+        [SOCKET_START_PRE] = UNIT_ACTIVATING,
+        [SOCKET_START_CHOWN] = UNIT_ACTIVATING,
+        [SOCKET_START_POST] = UNIT_ACTIVATING,
+        [SOCKET_LISTENING] = UNIT_ACTIVE,
+        [SOCKET_RUNNING] = UNIT_ACTIVE,
+        [SOCKET_STOP_PRE] = UNIT_DEACTIVATING,
+        [SOCKET_STOP_PRE_SIGTERM] = UNIT_DEACTIVATING,
+        [SOCKET_STOP_PRE_SIGKILL] = UNIT_DEACTIVATING,
+        [SOCKET_STOP_POST] = UNIT_DEACTIVATING,
+        [SOCKET_FINAL_SIGTERM] = UNIT_DEACTIVATING,
+        [SOCKET_FINAL_SIGKILL] = UNIT_DEACTIVATING,
+        [SOCKET_FAILED] = UNIT_FAILED,
+        [SOCKET_CLEANING] = UNIT_MAINTENANCE,
+};
+
+static int socket_dispatch_io(sd_event_source *source, int fd, uint32_t revents, void *userdata);
+static int socket_dispatch_timer(sd_event_source *source, usec_t usec, void *userdata);
+static void flush_ports(Socket *s);
+
+static void socket_init(Unit *u) {
+        Socket *s = SOCKET(u);
+
+        assert(u);
+        assert(u->load_state == UNIT_STUB);
+
+        s->backlog = SOMAXCONN_DELUXE;
+        s->timeout_usec = u->manager->default_timeout_start_usec;
+        s->directory_mode = 0755;
+        s->socket_mode = 0666;
+
+        s->max_connections = 64;
+
+        s->priority = -1;
+        s->ip_tos = -1;
+        s->ip_ttl = -1;
+        s->mark = -1;
+
+        s->exec_context.std_output = u->manager->default_std_output;
+        s->exec_context.std_error = u->manager->default_std_error;
+
+        s->control_command_id = _SOCKET_EXEC_COMMAND_INVALID;
+
+        s->trigger_limit.interval = USEC_INFINITY;
+        s->trigger_limit.burst = UINT_MAX;
+}
+
+static void socket_unwatch_control_pid(Socket *s) {
+        assert(s);
+
+        if (s->control_pid <= 0)
+                return;
+
+        unit_unwatch_pid(UNIT(s), TAKE_PID(s->control_pid));
+}
+
+static void socket_cleanup_fd_list(SocketPort *p) {
+        assert(p);
+
+        close_many(p->auxiliary_fds, p->n_auxiliary_fds);
+        p->auxiliary_fds = mfree(p->auxiliary_fds);
+        p->n_auxiliary_fds = 0;
+}
+
+SocketPort *socket_port_free(SocketPort *p) {
+        if (!p)
+                return NULL;
+
+        sd_event_source_unref(p->event_source);
+
+        socket_cleanup_fd_list(p);
+        safe_close(p->fd);
+        free(p->path);
+
+        return mfree(p);
+}
+
+void socket_free_ports(Socket *s) {
+        SocketPort *p;
+
+        assert(s);
+
+        while ((p = s->ports)) {
+                LIST_REMOVE(port, s->ports, p);
+                socket_port_free(p);
+        }
+}
+
+static void socket_done(Unit *u) {
+        Socket *s = SOCKET(u);
+        SocketPeer *p;
+
+        assert(s);
+
+        socket_free_ports(s);
+
+        while ((p = set_steal_first(s->peers_by_address)))
+                p->socket = NULL;
+
+        s->peers_by_address = set_free(s->peers_by_address);
+
+        s->exec_runtime = exec_runtime_unref(s->exec_runtime, false);
+        exec_command_free_array(s->exec_command, _SOCKET_EXEC_COMMAND_MAX);
+        s->control_command = NULL;
+
+        dynamic_creds_unref(&s->dynamic_creds);
+
+        socket_unwatch_control_pid(s);
+
+        unit_ref_unset(&s->service);
+
+        s->tcp_congestion = mfree(s->tcp_congestion);
+        s->bind_to_device = mfree(s->bind_to_device);
+
+        s->smack = mfree(s->smack);
+        s->smack_ip_in = mfree(s->smack_ip_in);
+        s->smack_ip_out = mfree(s->smack_ip_out);
+
+        strv_free(s->symlinks);
+
+        s->user = mfree(s->user);
+        s->group = mfree(s->group);
+
+        s->fdname = mfree(s->fdname);
+
+        s->timer_event_source = sd_event_source_disable_unref(s->timer_event_source);
+}
+
+static int socket_arm_timer(Socket *s, usec_t usec) {
+        int r;
+
+        assert(s);
+
+        if (s->timer_event_source) {
+                r = sd_event_source_set_time(s->timer_event_source, usec);
+                if (r < 0)
+                        return r;
+
+                return sd_event_source_set_enabled(s->timer_event_source, SD_EVENT_ONESHOT);
+        }
+
+        if (usec == USEC_INFINITY)
+                return 0;
+
+        r = sd_event_add_time(
+                        UNIT(s)->manager->event,
+                        &s->timer_event_source,
+                        CLOCK_MONOTONIC,
+                        usec, 0,
+                        socket_dispatch_timer, s);
+        if (r < 0)
+                return r;
+
+        (void) sd_event_source_set_description(s->timer_event_source, "socket-timer");
+
+        return 0;
+}
+
+static bool have_non_accept_socket(Socket *s) {
+        assert(s);
+
+        if (!s->accept)
+                return true;
+
+        LIST_FOREACH(port, p, s->ports) {
+
+                if (p->type != SOCKET_SOCKET)
+                        return true;
+
+                if (!socket_address_can_accept(&p->address))
+                        return true;
+        }
+
+        return false;
+}
+
+static int socket_add_mount_dependencies(Socket *s) {
+        int r;
+
+        assert(s);
+
+        LIST_FOREACH(port, p, s->ports) {
+                const char *path = NULL;
+
+                if (p->type == SOCKET_SOCKET)
+                        path = socket_address_get_path(&p->address);
+                else if (IN_SET(p->type, SOCKET_FIFO, SOCKET_SPECIAL, SOCKET_USB_FUNCTION))
+                        path = p->path;
+
+                if (!path)
+                        continue;
+
+                r = unit_require_mounts_for(UNIT(s), path, UNIT_DEPENDENCY_FILE);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int socket_add_device_dependencies(Socket *s) {
+        char *t;
+
+        assert(s);
+
+        if (!s->bind_to_device || streq(s->bind_to_device, "lo"))
+                return 0;
+
+        t = strjoina("/sys/subsystem/net/devices/", s->bind_to_device);
+        return unit_add_node_dependency(UNIT(s), t, UNIT_BINDS_TO, UNIT_DEPENDENCY_FILE);
+}
+
+static int socket_add_default_dependencies(Socket *s) {
+        int r;
+        assert(s);
+
+        if (!UNIT(s)->default_dependencies)
+                return 0;
+
+        r = unit_add_dependency_by_name(UNIT(s), UNIT_BEFORE, SPECIAL_SOCKETS_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
+        if (r < 0)
+                return r;
+
+        if (MANAGER_IS_SYSTEM(UNIT(s)->manager)) {
+                r = unit_add_two_dependencies_by_name(UNIT(s), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SYSINIT_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
+                if (r < 0)
+                        return r;
+        }
+
+        return unit_add_two_dependencies_by_name(UNIT(s), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_SHUTDOWN_TARGET, true, UNIT_DEPENDENCY_DEFAULT);
+}
+
+_pure_ static bool socket_has_exec(Socket *s) {
+        unsigned i;
+        assert(s);
+
+        for (i = 0; i < _SOCKET_EXEC_COMMAND_MAX; i++)
+                if (s->exec_command[i])
+                        return true;
+
+        return false;
+}
+
+static int socket_add_extras(Socket *s) {
+        Unit *u = UNIT(s);
+        int r;
+
+        assert(s);
+
+        /* Pick defaults for the trigger limit, if nothing was explicitly configured. We pick a relatively high limit
+         * in Accept=yes mode, and a lower limit for Accept=no. Reason: in Accept=yes mode we are invoking accept()
+         * ourselves before the trigger limit can hit, thus incoming connections are taken off the socket queue quickly
+         * and reliably. This is different for Accept=no, where the spawned service has to take the incoming traffic
+         * off the queues, which it might not necessarily do. Moreover, while Accept=no services are supposed to
+         * process whatever is queued in one go, and thus should normally never have to be started frequently. This is
+         * different for Accept=yes where each connection is processed by a new service instance, and thus frequent
+         * service starts are typical. */
+
+        if (s->trigger_limit.interval == USEC_INFINITY)
+                s->trigger_limit.interval = 2 * USEC_PER_SEC;
+
+        if (s->trigger_limit.burst == UINT_MAX) {
+                if (s->accept)
+                        s->trigger_limit.burst = 200;
+                else
+                        s->trigger_limit.burst = 20;
+        }
+
+        if (have_non_accept_socket(s)) {
+
+                if (!UNIT_DEREF(s->service)) {
+                        Unit *x;
+
+                        r = unit_load_related_unit(u, ".service", &x);
+                        if (r < 0)
+                                return r;
+
+                        unit_ref_set(&s->service, u, x);
+                }
+
+                r = unit_add_two_dependencies(u, UNIT_BEFORE, UNIT_TRIGGERS, UNIT_DEREF(s->service), true, UNIT_DEPENDENCY_IMPLICIT);
+                if (r < 0)
+                        return r;
+        }
+
+        r = socket_add_mount_dependencies(s);
+        if (r < 0)
+                return r;
+
+        r = socket_add_device_dependencies(s);
+        if (r < 0)
+                return r;
+
+        r = unit_patch_contexts(u);
+        if (r < 0)
+                return r;
+
+        if (socket_has_exec(s)) {
+                r = unit_add_exec_dependencies(u, &s->exec_context);
+                if (r < 0)
+                        return r;
+        }
+
+        r = unit_set_default_slice(u);
+        if (r < 0)
+                return r;
+
+        r = socket_add_default_dependencies(s);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+static const char *socket_find_symlink_target(Socket *s) {
+        const char *found = NULL;
+
+        LIST_FOREACH(port, p, s->ports) {
+                const char *f = NULL;
+
+                switch (p->type) {
+
+                case SOCKET_FIFO:
+                        f = p->path;
+                        break;
+
+                case SOCKET_SOCKET:
+                        f = socket_address_get_path(&p->address);
+                        break;
+
+                default:
+                        break;
+                }
+
+                if (f) {
+                        if (found)
+                                return NULL;
+
+                        found = f;
+                }
+        }
+
+        return found;
+}
+
+static int socket_verify(Socket *s) {
+        assert(s);
+        assert(UNIT(s)->load_state == UNIT_LOADED);
+
+        if (!s->ports)
+                return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Unit has no Listen setting (ListenStream=, ListenDatagram=, ListenFIFO=, ...). Refusing.");
+
+        if (s->accept && have_non_accept_socket(s))
+                return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Unit configured for accepting sockets, but sockets are non-accepting. Refusing.");
+
+        if (s->accept && s->max_connections <= 0)
+                return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "MaxConnection= setting too small. Refusing.");
+
+        if (s->accept && UNIT_DEREF(s->service))
+                return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Explicit service configuration for accepting socket units not supported. Refusing.");
+
+        if (s->exec_context.pam_name && s->kill_context.kill_mode != KILL_CONTROL_GROUP)
+                return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Unit has PAM enabled. Kill mode must be set to 'control-group'. Refusing.");
+
+        if (!strv_isempty(s->symlinks) && !socket_find_symlink_target(s))
+                return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Unit has symlinks set but none or more than one node in the file system. Refusing.");
+
+        return 0;
+}
+
+static void peer_address_hash_func(const SocketPeer *s, struct siphash *state) {
+        assert(s);
+
+        if (s->peer.sa.sa_family == AF_INET)
+                siphash24_compress(&s->peer.in.sin_addr, sizeof(s->peer.in.sin_addr), state);
+        else if (s->peer.sa.sa_family == AF_INET6)
+                siphash24_compress(&s->peer.in6.sin6_addr, sizeof(s->peer.in6.sin6_addr), state);
+        else if (s->peer.sa.sa_family == AF_VSOCK)
+                siphash24_compress(&s->peer.vm.svm_cid, sizeof(s->peer.vm.svm_cid), state);
+        else
+                assert_not_reached();
+}
+
+static int peer_address_compare_func(const SocketPeer *x, const SocketPeer *y) {
+        int r;
+
+        r = CMP(x->peer.sa.sa_family, y->peer.sa.sa_family);
+        if (r != 0)
+                return r;
+
+        switch (x->peer.sa.sa_family) {
+        case AF_INET:
+                return memcmp(&x->peer.in.sin_addr, &y->peer.in.sin_addr, sizeof(x->peer.in.sin_addr));
+        case AF_INET6:
+                return memcmp(&x->peer.in6.sin6_addr, &y->peer.in6.sin6_addr, sizeof(x->peer.in6.sin6_addr));
+        case AF_VSOCK:
+                return CMP(x->peer.vm.svm_cid, y->peer.vm.svm_cid);
+        }
+        assert_not_reached();
+}
+
+DEFINE_PRIVATE_HASH_OPS(peer_address_hash_ops, SocketPeer, peer_address_hash_func, peer_address_compare_func);
+
+static int socket_load(Unit *u) {
+        Socket *s = SOCKET(u);
+        int r;
+
+        assert(u);
+        assert(u->load_state == UNIT_STUB);
+
+        r = unit_load_fragment_and_dropin(u, true);
+        if (r < 0)
+                return r;
+
+        if (u->load_state != UNIT_LOADED)
+                return 0;
+
+        /* This is a new unit? Then let's add in some extras */
+        r = socket_add_extras(s);
+        if (r < 0)
+                return r;
+
+        return socket_verify(s);
+}
+
+static SocketPeer *socket_peer_new(void) {
+        SocketPeer *p;
+
+        p = new(SocketPeer, 1);
+        if (!p)
+                return NULL;
+
+        *p = (SocketPeer) {
+                .n_ref = 1,
+        };
+        return p;
+}
+
+static SocketPeer *socket_peer_free(SocketPeer *p) {
+        assert(p);
+
+        if (p->socket)
+                set_remove(p->socket->peers_by_address, p);
+
+        return mfree(p);
+}
+
+DEFINE_TRIVIAL_REF_UNREF_FUNC(SocketPeer, socket_peer, socket_peer_free);
+
+int socket_acquire_peer(Socket *s, int fd, SocketPeer **p) {
+        _cleanup_(socket_peer_unrefp) SocketPeer *remote = NULL;
+        SocketPeer sa = {
+                .peer_salen = sizeof(union sockaddr_union),
+        }, *i;
+        int r;
+
+        assert(fd >= 0);
+        assert(s);
+
+        if (getpeername(fd, &sa.peer.sa, &sa.peer_salen) < 0)
+                return log_unit_error_errno(UNIT(s), errno, "getpeername failed: %m");
+
+        if (!IN_SET(sa.peer.sa.sa_family, AF_INET, AF_INET6, AF_VSOCK)) {
+                *p = NULL;
+                return 0;
+        }
+
+        r = set_ensure_allocated(&s->peers_by_address, &peer_address_hash_ops);
+        if (r < 0)
+                return r;
+
+        i = set_get(s->peers_by_address, &sa);
+        if (i) {
+                *p = socket_peer_ref(i);
+                return 1;
+        }
+
+        remote = socket_peer_new();
+        if (!remote)
+                return log_oom();
+
+        remote->peer = sa.peer;
+        remote->peer_salen = sa.peer_salen;
+
+        r = set_put(s->peers_by_address, remote);
+        if (r < 0)
+                return r;
+
+        remote->socket = s;
+
+        *p = TAKE_PTR(remote);
+        return 1;
+}
+
+_const_ static const char* listen_lookup(int family, int type) {
+
+        if (family == AF_NETLINK)
+                return "ListenNetlink";
+
+        if (type == SOCK_STREAM)
+                return "ListenStream";
+        else if (type == SOCK_DGRAM)
+                return "ListenDatagram";
+        else if (type == SOCK_SEQPACKET)
+                return "ListenSequentialPacket";
+
+        assert_not_reached();
+        return NULL;
+}
+
+static void socket_dump(Unit *u, FILE *f, const char *prefix) {
+        Socket *s = SOCKET(u);
+        const char *prefix2, *str;
+
+        assert(s);
+        assert(f);
+
+        prefix = strempty(prefix);
+        prefix2 = strjoina(prefix, "\t");
+
+        fprintf(f,
+                "%sSocket State: %s\n"
+                "%sResult: %s\n"
+                "%sClean Result: %s\n"
+                "%sBindIPv6Only: %s\n"
+                "%sBacklog: %u\n"
+                "%sSocketMode: %04o\n"
+                "%sDirectoryMode: %04o\n"
+                "%sKeepAlive: %s\n"
+                "%sNoDelay: %s\n"
+                "%sFreeBind: %s\n"
+                "%sTransparent: %s\n"
+                "%sBroadcast: %s\n"
+                "%sPassCredentials: %s\n"
+                "%sPassSecurity: %s\n"
+                "%sPassPacketInfo: %s\n"
+                "%sTCPCongestion: %s\n"
+                "%sRemoveOnStop: %s\n"
+                "%sWritable: %s\n"
+                "%sFileDescriptorName: %s\n"
+                "%sSELinuxContextFromNet: %s\n",
+                prefix, socket_state_to_string(s->state),
+                prefix, socket_result_to_string(s->result),
+                prefix, socket_result_to_string(s->clean_result),
+                prefix, socket_address_bind_ipv6_only_to_string(s->bind_ipv6_only),
+                prefix, s->backlog,
+                prefix, s->socket_mode,
+                prefix, s->directory_mode,
+                prefix, yes_no(s->keep_alive),
+                prefix, yes_no(s->no_delay),
+                prefix, yes_no(s->free_bind),
+                prefix, yes_no(s->transparent),
+                prefix, yes_no(s->broadcast),
+                prefix, yes_no(s->pass_cred),
+                prefix, yes_no(s->pass_sec),
+                prefix, yes_no(s->pass_pktinfo),
+                prefix, strna(s->tcp_congestion),
+                prefix, yes_no(s->remove_on_stop),
+                prefix, yes_no(s->writable),
+                prefix, socket_fdname(s),
+                prefix, yes_no(s->selinux_context_from_net));
+
+        if (s->timestamping != SOCKET_TIMESTAMPING_OFF)
+                fprintf(f,
+                        "%sTimestamping: %s\n",
+                        prefix, socket_timestamping_to_string(s->timestamping));
+
+        if (s->control_pid > 0)
+                fprintf(f,
+                        "%sControl PID: "PID_FMT"\n",
+                        prefix, s->control_pid);
+
+        if (s->bind_to_device)
+                fprintf(f,
+                        "%sBindToDevice: %s\n",
+                        prefix, s->bind_to_device);
+
+        if (s->accept)
+                fprintf(f,
+                        "%sAccepted: %u\n"
+                        "%sNConnections: %u\n"
+                        "%sMaxConnections: %u\n"
+                        "%sMaxConnectionsPerSource: %u\n",
+                        prefix, s->n_accepted,
+                        prefix, s->n_connections,
+                        prefix, s->max_connections,
+                        prefix, s->max_connections_per_source);
+        else
+                fprintf(f,
+                        "%sFlushPending: %s\n",
+                         prefix, yes_no(s->flush_pending));
+
+
+        if (s->priority >= 0)
+                fprintf(f,
+                        "%sPriority: %i\n",
+                        prefix, s->priority);
+
+        if (s->receive_buffer > 0)
+                fprintf(f,
+                        "%sReceiveBuffer: %zu\n",
+                        prefix, s->receive_buffer);
+
+        if (s->send_buffer > 0)
+                fprintf(f,
+                        "%sSendBuffer: %zu\n",
+                        prefix, s->send_buffer);
+
+        if (s->ip_tos >= 0)
+                fprintf(f,
+                        "%sIPTOS: %i\n",
+                        prefix, s->ip_tos);
+
+        if (s->ip_ttl >= 0)
+                fprintf(f,
+                        "%sIPTTL: %i\n",
+                        prefix, s->ip_ttl);
+
+        if (s->pipe_size > 0)
+                fprintf(f,
+                        "%sPipeSize: %zu\n",
+                        prefix, s->pipe_size);
+
+        if (s->mark >= 0)
+                fprintf(f,
+                        "%sMark: %i\n",
+                        prefix, s->mark);
+
+        if (s->mq_maxmsg > 0)
+                fprintf(f,
+                        "%sMessageQueueMaxMessages: %li\n",
+                        prefix, s->mq_maxmsg);
+
+        if (s->mq_msgsize > 0)
+                fprintf(f,
+                        "%sMessageQueueMessageSize: %li\n",
+                        prefix, s->mq_msgsize);
+
+        if (s->reuse_port)
+                fprintf(f,
+                        "%sReusePort: %s\n",
+                         prefix, yes_no(s->reuse_port));
+
+        if (s->smack)
+                fprintf(f,
+                        "%sSmackLabel: %s\n",
+                        prefix, s->smack);
+
+        if (s->smack_ip_in)
+                fprintf(f,
+                        "%sSmackLabelIPIn: %s\n",
+                        prefix, s->smack_ip_in);
+
+        if (s->smack_ip_out)
+                fprintf(f,
+                        "%sSmackLabelIPOut: %s\n",
+                        prefix, s->smack_ip_out);
+
+        if (!isempty(s->user) || !isempty(s->group))
+                fprintf(f,
+                        "%sSocketUser: %s\n"
+                        "%sSocketGroup: %s\n",
+                        prefix, strna(s->user),
+                        prefix, strna(s->group));
+
+        if (s->keep_alive_time > 0)
+                fprintf(f,
+                        "%sKeepAliveTimeSec: %s\n",
+                        prefix, FORMAT_TIMESPAN(s->keep_alive_time, USEC_PER_SEC));
+
+        if (s->keep_alive_interval > 0)
+                fprintf(f,
+                        "%sKeepAliveIntervalSec: %s\n",
+                        prefix, FORMAT_TIMESPAN(s->keep_alive_interval, USEC_PER_SEC));
+
+        if (s->keep_alive_cnt > 0)
+                fprintf(f,
+                        "%sKeepAliveProbes: %u\n",
+                        prefix, s->keep_alive_cnt);
+
+        if (s->defer_accept > 0)
+                fprintf(f,
+                        "%sDeferAcceptSec: %s\n",
+                        prefix, FORMAT_TIMESPAN(s->defer_accept, USEC_PER_SEC));
+
+        LIST_FOREACH(port, p, s->ports) {
+
+                switch (p->type) {
+                case SOCKET_SOCKET: {
+                        _cleanup_free_ char *k = NULL;
+                        int r;
+
+                        r = socket_address_print(&p->address, &k);
+                        if (r < 0) {
+                                errno = -r;
+                                fprintf(f, "%s%s: %m\n", prefix, listen_lookup(socket_address_family(&p->address), p->address.type));
+                        } else
+                                fprintf(f, "%s%s: %s\n", prefix, listen_lookup(socket_address_family(&p->address), p->address.type), k);
+                        break;
+                }
+                case SOCKET_SPECIAL:
+                        fprintf(f, "%sListenSpecial: %s\n", prefix, p->path);
+                        break;
+                case SOCKET_USB_FUNCTION:
+                        fprintf(f, "%sListenUSBFunction: %s\n", prefix, p->path);
+                        break;
+                case SOCKET_MQUEUE:
+                        fprintf(f, "%sListenMessageQueue: %s\n", prefix, p->path);
+                        break;
+                default:
+                        fprintf(f, "%sListenFIFO: %s\n", prefix, p->path);
+                }
+        }
+
+        fprintf(f,
+                "%sTriggerLimitIntervalSec: %s\n"
+                "%sTriggerLimitBurst: %u\n",
+                prefix, FORMAT_TIMESPAN(s->trigger_limit.interval, USEC_PER_SEC),
+                prefix, s->trigger_limit.burst);
+
+        str = ip_protocol_to_name(s->socket_protocol);
+        if (str)
+                fprintf(f, "%sSocketProtocol: %s\n", prefix, str);
+
+        if (!strv_isempty(s->symlinks)) {
+                fprintf(f, "%sSymlinks:", prefix);
+                STRV_FOREACH(q, s->symlinks)
+                        fprintf(f, " %s", *q);
+
+                fprintf(f, "\n");
+        }
+
+        fprintf(f,
+                "%sTimeoutSec: %s\n",
+                prefix, FORMAT_TIMESPAN(s->timeout_usec, USEC_PER_SEC));
+
+        exec_context_dump(&s->exec_context, f, prefix);
+        kill_context_dump(&s->kill_context, f, prefix);
+
+        for (SocketExecCommand c = 0; c < _SOCKET_EXEC_COMMAND_MAX; c++) {
+                if (!s->exec_command[c])
+                        continue;
+
+                fprintf(f, "%s-> %s:\n",
+                        prefix, socket_exec_command_to_string(c));
+
+                exec_command_dump_list(s->exec_command[c], f, prefix2);
+        }
+
+        cgroup_context_dump(UNIT(s), f, prefix);
+}
+
+static int instance_from_socket(int fd, unsigned nr, char **instance) {
+        socklen_t l;
+        char *r;
+        union sockaddr_union local, remote;
+
+        assert(fd >= 0);
+        assert(instance);
+
+        l = sizeof(local);
+        if (getsockname(fd, &local.sa, &l) < 0)
+                return -errno;
+
+        l = sizeof(remote);
+        if (getpeername(fd, &remote.sa, &l) < 0)
+                return -errno;
+
+        switch (local.sa.sa_family) {
+
+        case AF_INET: {
+                uint32_t
+                        a = be32toh(local.in.sin_addr.s_addr),
+                        b = be32toh(remote.in.sin_addr.s_addr);
+
+                if (asprintf(&r,
+                             "%u-%u.%u.%u.%u:%u-%u.%u.%u.%u:%u",
+                             nr,
+                             a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF,
+                             be16toh(local.in.sin_port),
+                             b >> 24, (b >> 16) & 0xFF, (b >> 8) & 0xFF, b & 0xFF,
+                             be16toh(remote.in.sin_port)) < 0)
+                        return -ENOMEM;
+
+                break;
+        }
+
+        case AF_INET6: {
+                static const unsigned char ipv4_prefix[] = {
+                        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF
+                };
+
+                if (memcmp(&local.in6.sin6_addr, ipv4_prefix, sizeof(ipv4_prefix)) == 0 &&
+                    memcmp(&remote.in6.sin6_addr, ipv4_prefix, sizeof(ipv4_prefix)) == 0) {
+                        const uint8_t
+                                *a = local.in6.sin6_addr.s6_addr+12,
+                                *b = remote.in6.sin6_addr.s6_addr+12;
+
+                        if (asprintf(&r,
+                                     "%u-%u.%u.%u.%u:%u-%u.%u.%u.%u:%u",
+                                     nr,
+                                     a[0], a[1], a[2], a[3],
+                                     be16toh(local.in6.sin6_port),
+                                     b[0], b[1], b[2], b[3],
+                                     be16toh(remote.in6.sin6_port)) < 0)
+                                return -ENOMEM;
+                } else {
+                        if (asprintf(&r,
+                                     "%u-%s:%u-%s:%u",
+                                     nr,
+                                     IN6_ADDR_TO_STRING(&local.in6.sin6_addr),
+                                     be16toh(local.in6.sin6_port),
+                                     IN6_ADDR_TO_STRING(&remote.in6.sin6_addr),
+                                     be16toh(remote.in6.sin6_port)) < 0)
+                                return -ENOMEM;
+                }
+
+                break;
+        }
+
+        case AF_UNIX: {
+                struct ucred ucred;
+                int k;
+
+                k = getpeercred(fd, &ucred);
+                if (k >= 0) {
+                        if (asprintf(&r,
+                                     "%u-"PID_FMT"-"UID_FMT,
+                                     nr, ucred.pid, ucred.uid) < 0)
+                                return -ENOMEM;
+                } else if (k == -ENODATA) {
+                        /* This handles the case where somebody is
+                         * connecting from another pid/uid namespace
+                         * (e.g. from outside of our container). */
+                        if (asprintf(&r,
+                                     "%u-unknown",
+                                     nr) < 0)
+                                return -ENOMEM;
+                } else
+                        return k;
+
+                break;
+        }
+
+        case AF_VSOCK:
+                if (asprintf(&r,
+                             "%u-%u:%u-%u:%u",
+                             nr,
+                             local.vm.svm_cid, local.vm.svm_port,
+                             remote.vm.svm_cid, remote.vm.svm_port) < 0)
+                        return -ENOMEM;
+
+                break;
+
+        default:
+                assert_not_reached();
+        }
+
+        *instance = r;
+        return 0;
+}
+
+static void socket_close_fds(Socket *s) {
+        assert(s);
+
+        LIST_FOREACH(port, p, s->ports) {
+                bool was_open;
+
+                was_open = p->fd >= 0;
+
+                p->event_source = sd_event_source_disable_unref(p->event_source);
+                p->fd = safe_close(p->fd);
+                socket_cleanup_fd_list(p);
+
+                /* One little note: we should normally not delete any sockets in the file system here! After all some
+                 * other process we spawned might still have a reference of this fd and wants to continue to use
+                 * it. Therefore we normally delete sockets in the file system before we create a new one, not after we
+                 * stopped using one! That all said, if the user explicitly requested this, we'll delete them here
+                 * anyway, but only then. */
+
+                if (!was_open || !s->remove_on_stop)
+                        continue;
+
+                switch (p->type) {
+
+                case SOCKET_FIFO:
+                        (void) unlink(p->path);
+                        break;
+
+                case SOCKET_MQUEUE:
+                        (void) mq_unlink(p->path);
+                        break;
+
+                case SOCKET_SOCKET:
+                        (void) socket_address_unlink(&p->address);
+                        break;
+
+                default:
+                        break;
+                }
+        }
+
+        if (s->remove_on_stop)
+                STRV_FOREACH(i, s->symlinks)
+                        (void) unlink(*i);
+
+        /* Note that we don't return NULL here, since s has not been freed. */
+}
+
+static void socket_apply_socket_options(Socket *s, SocketPort *p, int fd) {
+        int r;
+
+        assert(s);
+        assert(p);
+        assert(fd >= 0);
+
+        if (s->keep_alive) {
+                r = setsockopt_int(fd, SOL_SOCKET, SO_KEEPALIVE, true);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "SO_KEEPALIVE failed: %m");
+        }
+
+        if (s->keep_alive_time > 0) {
+                r = setsockopt_int(fd, SOL_TCP, TCP_KEEPIDLE, s->keep_alive_time / USEC_PER_SEC);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "TCP_KEEPIDLE failed: %m");
+        }
+
+        if (s->keep_alive_interval > 0) {
+                r = setsockopt_int(fd, SOL_TCP, TCP_KEEPINTVL, s->keep_alive_interval / USEC_PER_SEC);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "TCP_KEEPINTVL failed: %m");
+        }
+
+        if (s->keep_alive_cnt > 0) {
+                r = setsockopt_int(fd, SOL_TCP, TCP_KEEPCNT, s->keep_alive_cnt);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "TCP_KEEPCNT failed: %m");
+        }
+
+        if (s->defer_accept > 0) {
+                r = setsockopt_int(fd, SOL_TCP, TCP_DEFER_ACCEPT, s->defer_accept / USEC_PER_SEC);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "TCP_DEFER_ACCEPT failed: %m");
+        }
+
+        if (s->no_delay) {
+                if (s->socket_protocol == IPPROTO_SCTP) {
+                        r = setsockopt_int(fd, SOL_SCTP, SCTP_NODELAY, true);
+                        if (r < 0)
+                                log_unit_warning_errno(UNIT(s), r, "SCTP_NODELAY failed: %m");
+                } else {
+                        r = setsockopt_int(fd, SOL_TCP, TCP_NODELAY, true);
+                        if (r < 0)
+                                log_unit_warning_errno(UNIT(s), r, "TCP_NODELAY failed: %m");
+                }
+        }
+
+        if (s->broadcast) {
+                r = setsockopt_int(fd, SOL_SOCKET, SO_BROADCAST, true);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "SO_BROADCAST failed: %m");
+        }
+
+        if (s->pass_cred) {
+                r = setsockopt_int(fd, SOL_SOCKET, SO_PASSCRED, true);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "SO_PASSCRED failed: %m");
+        }
+
+        if (s->pass_sec) {
+                r = setsockopt_int(fd, SOL_SOCKET, SO_PASSSEC, true);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "SO_PASSSEC failed: %m");
+        }
+
+        if (s->pass_pktinfo) {
+                r = socket_set_recvpktinfo(fd, socket_address_family(&p->address), true);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "Failed to enable packet info socket option: %m");
+        }
+
+        if (s->timestamping != SOCKET_TIMESTAMPING_OFF) {
+                r = setsockopt_int(fd, SOL_SOCKET,
+                                   s->timestamping == SOCKET_TIMESTAMPING_NS ? SO_TIMESTAMPNS : SO_TIMESTAMP,
+                                   true);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "Failed to enable timestamping socket option, ignoring: %m");
+        }
+
+        if (s->priority >= 0) {
+                r = setsockopt_int(fd, SOL_SOCKET, SO_PRIORITY, s->priority);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "SO_PRIORITY failed: %m");
+        }
+
+        if (s->receive_buffer > 0) {
+                r = fd_set_rcvbuf(fd, s->receive_buffer, false);
+                if (r < 0)
+                        log_unit_full_errno(UNIT(s), ERRNO_IS_PRIVILEGE(r) ? LOG_DEBUG : LOG_WARNING, r,
+                                            "SO_RCVBUF/SO_RCVBUFFORCE failed: %m");
+        }
+
+        if (s->send_buffer > 0) {
+                r = fd_set_sndbuf(fd, s->send_buffer, false);
+                if (r < 0)
+                        log_unit_full_errno(UNIT(s), ERRNO_IS_PRIVILEGE(r) ? LOG_DEBUG : LOG_WARNING, r,
+                                            "SO_SNDBUF/SO_SNDBUFFORCE failed: %m");
+        }
+
+        if (s->mark >= 0) {
+                r = setsockopt_int(fd, SOL_SOCKET, SO_MARK, s->mark);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "SO_MARK failed: %m");
+        }
+
+        if (s->ip_tos >= 0) {
+                r = setsockopt_int(fd, IPPROTO_IP, IP_TOS, s->ip_tos);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "IP_TOS failed: %m");
+        }
+
+        if (s->ip_ttl >= 0) {
+                r = socket_set_ttl(fd, socket_address_family(&p->address), s->ip_ttl);
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "IP_TTL/IPV6_UNICAST_HOPS failed: %m");
+        }
+
+        if (s->tcp_congestion)
+                if (setsockopt(fd, SOL_TCP, TCP_CONGESTION, s->tcp_congestion, strlen(s->tcp_congestion)+1) < 0)
+                        log_unit_warning_errno(UNIT(s), errno, "TCP_CONGESTION failed: %m");
+
+        if (s->smack_ip_in) {
+                r = mac_smack_apply_fd(fd, SMACK_ATTR_IPIN, s->smack_ip_in);
+                if (r < 0)
+                        log_unit_error_errno(UNIT(s), r, "mac_smack_apply_ip_in_fd: %m");
+        }
+
+        if (s->smack_ip_out) {
+                r = mac_smack_apply_fd(fd, SMACK_ATTR_IPOUT, s->smack_ip_out);
+                if (r < 0)
+                        log_unit_error_errno(UNIT(s), r, "mac_smack_apply_ip_out_fd: %m");
+        }
+}
+
+static void socket_apply_fifo_options(Socket *s, int fd) {
+        int r;
+
+        assert(s);
+        assert(fd >= 0);
+
+        if (s->pipe_size > 0)
+                if (fcntl(fd, F_SETPIPE_SZ, s->pipe_size) < 0)
+                        log_unit_warning_errno(UNIT(s), errno, "Setting pipe size failed, ignoring: %m");
+
+        if (s->smack) {
+                r = mac_smack_apply_fd(fd, SMACK_ATTR_ACCESS, s->smack);
+                if (r < 0)
+                        log_unit_error_errno(UNIT(s), r, "SMACK relabelling failed, ignoring: %m");
+        }
+}
+
+static int fifo_address_create(
+                const char *path,
+                mode_t directory_mode,
+                mode_t socket_mode) {
+
+        _cleanup_close_ int fd = -1;
+        mode_t old_mask;
+        struct stat st;
+        int r;
+
+        assert(path);
+
+        (void) mkdir_parents_label(path, directory_mode);
+
+        r = mac_selinux_create_file_prepare(path, S_IFIFO);
+        if (r < 0)
+                return r;
+
+        /* Enforce the right access mode for the fifo */
+        old_mask = umask(~socket_mode);
+
+        /* Include the original umask in our mask */
+        (void) umask(~socket_mode | old_mask);
+
+        r = mkfifo(path, socket_mode);
+        (void) umask(old_mask);
+
+        if (r < 0 && errno != EEXIST) {
+                r = -errno;
+                goto fail;
+        }
+
+        fd = open(path, O_RDWR | O_CLOEXEC | O_NOCTTY | O_NONBLOCK | O_NOFOLLOW);
+        if (fd < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        mac_selinux_create_file_clear();
+
+        if (fstat(fd, &st) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        if (!S_ISFIFO(st.st_mode) ||
+            (st.st_mode & 0777) != (socket_mode & ~old_mask) ||
+            st.st_uid != getuid() ||
+            st.st_gid != getgid()) {
+                r = -EEXIST;
+                goto fail;
+        }
+
+        return TAKE_FD(fd);
+
+fail:
+        mac_selinux_create_file_clear();
+        return r;
+}
+
+static int special_address_create(const char *path, bool writable) {
+        _cleanup_close_ int fd = -1;
+        struct stat st;
+
+        assert(path);
+
+        fd = open(path, (writable ? O_RDWR : O_RDONLY)|O_CLOEXEC|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW);
+        if (fd < 0)
+                return -errno;
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        /* Check whether this is a /proc, /sys or /dev file or char device */
+        if (!S_ISREG(st.st_mode) && !S_ISCHR(st.st_mode))
+                return -EEXIST;
+
+        return TAKE_FD(fd);
+}
+
+static int usbffs_address_create(const char *path) {
+        _cleanup_close_ int fd = -1;
+        struct stat st;
+
+        assert(path);
+
+        fd = open(path, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW);
+        if (fd < 0)
+                return -errno;
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        /* Check whether this is a regular file (ffs endpoint) */
+        if (!S_ISREG(st.st_mode))
+                return -EEXIST;
+
+        return TAKE_FD(fd);
+}
+
+static int mq_address_create(
+                const char *path,
+                mode_t mq_mode,
+                long maxmsg,
+                long msgsize) {
+
+        _cleanup_close_ int fd = -1;
+        struct stat st;
+        mode_t old_mask;
+        struct mq_attr _attr, *attr = NULL;
+
+        assert(path);
+
+        if (maxmsg > 0 && msgsize > 0) {
+                _attr = (struct mq_attr) {
+                        .mq_flags = O_NONBLOCK,
+                        .mq_maxmsg = maxmsg,
+                        .mq_msgsize = msgsize,
+                };
+                attr = &_attr;
+        }
+
+        /* Enforce the right access mode for the mq */
+        old_mask = umask(~mq_mode);
+
+        /* Include the original umask in our mask */
+        (void) umask(~mq_mode | old_mask);
+        fd = mq_open(path, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_CREAT, mq_mode, attr);
+        (void) umask(old_mask);
+
+        if (fd < 0)
+                return -errno;
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        if ((st.st_mode & 0777) != (mq_mode & ~old_mask) ||
+            st.st_uid != getuid() ||
+            st.st_gid != getgid())
+                return -EEXIST;
+
+        return TAKE_FD(fd);
+}
+
+static int socket_symlink(Socket *s) {
+        const char *p;
+        int r;
+
+        assert(s);
+
+        p = socket_find_symlink_target(s);
+        if (!p)
+                return 0;
+
+        STRV_FOREACH(i, s->symlinks) {
+                (void) mkdir_parents_label(*i, s->directory_mode);
+
+                r = symlink_idempotent(p, *i, false);
+
+                if (r == -EEXIST && s->remove_on_stop) {
+                        /* If there's already something where we want to create the symlink, and the destructive
+                         * RemoveOnStop= mode is set, then we might as well try to remove what already exists and try
+                         * again. */
+
+                        if (unlink(*i) >= 0)
+                                r = symlink_idempotent(p, *i, false);
+                }
+
+                if (r < 0)
+                        log_unit_warning_errno(UNIT(s), r, "Failed to create symlink %s %s %s, ignoring: %m",
+                                               p, special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), *i);
+        }
+
+        return 0;
+}
+
+static int usbffs_write_descs(int fd, Service *s) {
+        int r;
+
+        if (!s->usb_function_descriptors || !s->usb_function_strings)
+                return -EINVAL;
+
+        r = copy_file_fd(s->usb_function_descriptors, fd, 0);
+        if (r < 0)
+                return r;
+
+        return copy_file_fd(s->usb_function_strings, fd, 0);
+}
+
+static int usbffs_select_ep(const struct dirent *d) {
+        return d->d_name[0] != '.' && !streq(d->d_name, "ep0");
+}
+
+static int usbffs_dispatch_eps(SocketPort *p) {
+        _cleanup_free_ struct dirent **ent = NULL;
+        size_t n, k;
+        int r;
+
+        r = scandir(p->path, &ent, usbffs_select_ep, alphasort);
+        if (r < 0)
+                return -errno;
+
+        n = (size_t) r;
+        p->auxiliary_fds = new(int, n);
+        if (!p->auxiliary_fds) {
+                r = -ENOMEM;
+                goto clear;
+        }
+
+        p->n_auxiliary_fds = n;
+
+        k = 0;
+        for (size_t i = 0; i < n; ++i) {
+                _cleanup_free_ char *ep = NULL;
+
+                ep = path_make_absolute(ent[i]->d_name, p->path);
+                if (!ep) {
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                path_simplify(ep);
+
+                r = usbffs_address_create(ep);
+                if (r < 0)
+                        goto fail;
+
+                p->auxiliary_fds[k++] = r;
+        }
+
+        r = 0;
+        goto clear;
+
+fail:
+        close_many(p->auxiliary_fds, k);
+        p->auxiliary_fds = mfree(p->auxiliary_fds);
+        p->n_auxiliary_fds = 0;
+
+clear:
+        for (size_t i = 0; i < n; ++i)
+                free(ent[i]);
+
+        return r;
+}
+
+int socket_load_service_unit(Socket *s, int cfd, Unit **ret) {
+        /* Figure out what the unit that will be used to handle the connections on the socket looks like.
+         *
+         * If cfd < 0, then we don't have a connection yet. In case of Accept=yes sockets, use a fake
+         * instance name.
+         */
+
+        if (UNIT_ISSET(s->service)) {
+                *ret = UNIT_DEREF(s->service);
+                return 0;
+        }
+
+        if (!s->accept)
+                return -ENODATA;
+
+        /* Build the instance name and load the unit */
+        _cleanup_free_ char *prefix = NULL, *instance = NULL, *name = NULL;
+        int r;
+
+        r = unit_name_to_prefix(UNIT(s)->id, &prefix);
+        if (r < 0)
+                return r;
+
+        if (cfd >= 0) {
+                r = instance_from_socket(cfd, s->n_accepted, &instance);
+                if (ERRNO_IS_DISCONNECT(r))
+                        /* ENOTCONN is legitimate if TCP RST was received. Other socket families might return
+                         * different errors. This connection is over, but the socket unit lives on. */
+                        return log_unit_debug_errno(UNIT(s), r,
+                                                    "Got %s on incoming socket, assuming aborted connection attempt, ignoring.",
+                                                    errno_to_name(r));
+                if (r < 0)
+                        return r;
+        }
+
+        /* For accepting sockets, we don't know how the instance will be called until we get a connection and
+         * can figure out what the peer name is. So let's use "internal" as the instance to make it clear
+         * that this is not an actual peer name. We use "unknown" when we cannot figure out the peer. */
+        r = unit_name_build(prefix, instance ?: "internal", ".service", &name);
+        if (r < 0)
+                return r;
+
+        return manager_load_unit(UNIT(s)->manager, name, NULL, NULL, ret);
+}
+
+static int socket_determine_selinux_label(Socket *s, char **ret) {
+        int r;
+
+        assert(s);
+        assert(ret);
+
+        Unit *service;
+        ExecCommand *c;
+        const char *exec_context;
+        _cleanup_free_ char *path = NULL;
+
+        r = socket_load_service_unit(s, -1, &service);
+        if (r == -ENODATA)
+                goto no_label;
+        if (r < 0)
+                return r;
+
+        exec_context = SERVICE(service)->exec_context.selinux_context;
+        if (exec_context) {
+                char *con;
+
+                con = strdup(exec_context);
+                if (!con)
+                        return -ENOMEM;
+
+                *ret = TAKE_PTR(con);
+                return 0;
+        }
+
+        c = SERVICE(service)->exec_command[SERVICE_EXEC_START];
+        if (!c)
+                goto no_label;
+
+        r = chase_symlinks(c->path, SERVICE(service)->exec_context.root_directory, CHASE_PREFIX_ROOT, &path, NULL);
+        if (r < 0)
+                goto no_label;
+
+        r = mac_selinux_get_create_label_from_exe(path, ret);
+        if (IN_SET(r, -EPERM, -EOPNOTSUPP))
+                goto no_label;
+        return r;
+
+no_label:
+        *ret = NULL;
+        return 0;
+}
+
+static int socket_address_listen_do(
+                Socket *s,
+                const SocketAddress *address,
+                const char *label) {
+
+        assert(s);
+        assert(address);
+
+        return socket_address_listen(
+                        address,
+                        SOCK_CLOEXEC|SOCK_NONBLOCK,
+                        s->backlog,
+                        s->bind_ipv6_only,
+                        s->bind_to_device,
+                        s->reuse_port,
+                        s->free_bind,
+                        s->transparent,
+                        s->directory_mode,
+                        s->socket_mode,
+                        label);
+}
+
+#define log_address_error_errno(u, address, error, fmt)          \
+        ({                                                       \
+                _cleanup_free_ char *_t = NULL;                  \
+                                                                 \
+                (void) socket_address_print(address, &_t);       \
+                log_unit_error_errno(u, error, fmt, strna(_t));  \
+        })
+
+static int fork_needed(const SocketAddress *address, const ExecContext *context) {
+        int r;
+
+        assert(address);
+        assert(context);
+
+        /* Check if we need to do the cgroup or netns stuff. If not we can do things much simpler. */
+
+        if (IN_SET(address->sockaddr.sa.sa_family, AF_INET, AF_INET6)) {
+                r = bpf_firewall_supported();
+                if (r < 0)
+                        return r;
+                if (r != BPF_FIREWALL_UNSUPPORTED) /* If BPF firewalling isn't supported anyway — there's no point in this forking complexity */
+                        return true;
+        }
+
+        return context->private_network || context->network_namespace_path;
+}
+
+static int socket_address_listen_in_cgroup(
+                Socket *s,
+                const SocketAddress *address,
+                const char *label) {
+
+        _cleanup_close_pair_ int pair[2] = { -1, -1 };
+        int fd, r;
+        pid_t pid;
+
+        assert(s);
+        assert(address);
+
+        /* This is a wrapper around socket_address_listen(), that forks off a helper process inside the
+         * socket's cgroup and network namespace in which the socket is actually created. This way we ensure
+         * the socket is actually properly attached to the unit's cgroup for the purpose of BPF filtering and
+         * such. */
+
+        r = fork_needed(address, &s->exec_context);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                /* Shortcut things... */
+                fd = socket_address_listen_do(s, address, label);
+                if (fd < 0)
+                        return log_address_error_errno(UNIT(s), address, fd, "Failed to create listening socket (%s): %m");
+
+                return fd;
+        }
+
+        r = unit_setup_exec_runtime(UNIT(s));
+        if (r < 0)
+                return log_unit_error_errno(UNIT(s), r, "Failed acquire runtime: %m");
+
+        if (s->exec_context.network_namespace_path &&
+            s->exec_runtime &&
+            s->exec_runtime->netns_storage_socket[0] >= 0) {
+                r = open_shareable_ns_path(s->exec_runtime->netns_storage_socket, s->exec_context.network_namespace_path, CLONE_NEWNET);
+                if (r < 0)
+                        return log_unit_error_errno(UNIT(s), r, "Failed to open network namespace path %s: %m", s->exec_context.network_namespace_path);
+        }
+
+        if (s->exec_context.ipc_namespace_path &&
+            s->exec_runtime &&
+            s->exec_runtime->ipcns_storage_socket[0] >= 0) {
+                r = open_shareable_ns_path(s->exec_runtime->ipcns_storage_socket, s->exec_context.ipc_namespace_path, CLONE_NEWIPC);
+                if (r < 0)
+                        return log_unit_error_errno(UNIT(s), r, "Failed to open IPC namespace path %s: %m", s->exec_context.ipc_namespace_path);
+        }
+
+        if (socketpair(AF_UNIX, SOCK_SEQPACKET|SOCK_CLOEXEC, 0, pair) < 0)
+                return log_unit_error_errno(UNIT(s), errno, "Failed to create communication channel: %m");
+
+        r = unit_fork_helper_process(UNIT(s), "(sd-listen)", &pid);
+        if (r < 0)
+                return log_unit_error_errno(UNIT(s), r, "Failed to fork off listener stub process: %m");
+        if (r == 0) {
+                /* Child */
+
+                pair[0] = safe_close(pair[0]);
+
+                if ((s->exec_context.private_network || s->exec_context.network_namespace_path) &&
+                    s->exec_runtime &&
+                    s->exec_runtime->netns_storage_socket[0] >= 0) {
+
+                        if (ns_type_supported(NAMESPACE_NET)) {
+                                r = setup_shareable_ns(s->exec_runtime->netns_storage_socket, CLONE_NEWNET);
+                                if (r < 0) {
+                                        log_unit_error_errno(UNIT(s), r, "Failed to join network namespace: %m");
+                                        _exit(EXIT_NETWORK);
+                                }
+                        } else if (s->exec_context.network_namespace_path) {
+                                log_unit_error(UNIT(s), "Network namespace path configured but network namespaces not supported.");
+                                _exit(EXIT_NETWORK);
+                        } else
+                                log_unit_warning(UNIT(s), "PrivateNetwork=yes is configured, but the kernel does not support network namespaces, ignoring.");
+                }
+
+                fd = socket_address_listen_do(s, address, label);
+                if (fd < 0) {
+                        log_address_error_errno(UNIT(s), address, fd, "Failed to create listening socket (%s): %m");
+                        _exit(EXIT_FAILURE);
+                }
+
+                r = send_one_fd(pair[1], fd, 0);
+                if (r < 0) {
+                        log_address_error_errno(UNIT(s), address, r, "Failed to send listening socket (%s) to parent: %m");
+                        _exit(EXIT_FAILURE);
+                }
+
+                _exit(EXIT_SUCCESS);
+        }
+
+        pair[1] = safe_close(pair[1]);
+        fd = receive_one_fd(pair[0], 0);
+
+        /* We synchronously wait for the helper, as it shouldn't be slow */
+        r = wait_for_terminate_and_check("(sd-listen)", pid, WAIT_LOG_ABNORMAL);
+        if (r < 0) {
+                safe_close(fd);
+                return r;
+        }
+
+        if (fd < 0)
+                return log_address_error_errno(UNIT(s), address, fd, "Failed to receive listening socket (%s): %m");
+
+        return fd;
+}
+
+DEFINE_TRIVIAL_CLEANUP_FUNC_FULL(Socket *, socket_close_fds, NULL);
+
+static int socket_open_fds(Socket *orig_s) {
+        _cleanup_(socket_close_fdsp) Socket *s = orig_s;
+        _cleanup_(mac_selinux_freep) char *label = NULL;
+        bool know_label = false;
+        int r;
+
+        assert(s);
+
+        LIST_FOREACH(port, p, s->ports) {
+
+                if (p->fd >= 0)
+                        continue;
+
+                switch (p->type) {
+
+                case SOCKET_SOCKET:
+
+                        if (!know_label) {
+                                /* Figure out the label, if we don't it know yet. We do it once for the first
+                                 * socket where we need this and remember it for the rest. */
+
+                                r = socket_determine_selinux_label(s, &label);
+                                if (r < 0)
+                                        return log_unit_error_errno(UNIT(s), r, "Failed to determine SELinux label: %m");
+
+                                know_label = true;
+                        }
+
+                        /* Apply the socket protocol */
+                        switch (p->address.type) {
+
+                        case SOCK_STREAM:
+                        case SOCK_SEQPACKET:
+                                if (s->socket_protocol == IPPROTO_SCTP)
+                                        p->address.protocol = s->socket_protocol;
+                                break;
+
+                        case SOCK_DGRAM:
+                                if (s->socket_protocol == IPPROTO_UDPLITE)
+                                        p->address.protocol = s->socket_protocol;
+                                break;
+                        }
+
+                        p->fd = socket_address_listen_in_cgroup(s, &p->address, label);
+                        if (p->fd < 0)
+                                return p->fd;
+
+                        socket_apply_socket_options(s, p, p->fd);
+                        socket_symlink(s);
+                        break;
+
+                case SOCKET_SPECIAL:
+
+                        p->fd = special_address_create(p->path, s->writable);
+                        if (p->fd < 0)
+                                return log_unit_error_errno(UNIT(s), p->fd, "Failed to open special file %s: %m", p->path);
+                        break;
+
+                case SOCKET_FIFO:
+
+                        p->fd = fifo_address_create(
+                                        p->path,
+                                        s->directory_mode,
+                                        s->socket_mode);
+                        if (p->fd < 0)
+                                return log_unit_error_errno(UNIT(s), p->fd, "Failed to open FIFO %s: %m", p->path);
+
+                        socket_apply_fifo_options(s, p->fd);
+                        socket_symlink(s);
+                        break;
+
+                case SOCKET_MQUEUE:
+
+                        p->fd = mq_address_create(
+                                        p->path,
+                                        s->socket_mode,
+                                        s->mq_maxmsg,
+                                        s->mq_msgsize);
+                        if (p->fd < 0)
+                                return log_unit_error_errno(UNIT(s), p->fd, "Failed to open message queue %s: %m", p->path);
+                        break;
+
+                case SOCKET_USB_FUNCTION: {
+                        _cleanup_free_ char *ep = NULL;
+
+                        ep = path_make_absolute("ep0", p->path);
+                        if (!ep)
+                                return -ENOMEM;
+
+                        p->fd = usbffs_address_create(ep);
+                        if (p->fd < 0)
+                                return p->fd;
+
+                        r = usbffs_write_descs(p->fd, SERVICE(UNIT_DEREF(s->service)));
+                        if (r < 0)
+                                return r;
+
+                        r = usbffs_dispatch_eps(p);
+                        if (r < 0)
+                                return r;
+
+                        break;
+                }
+                default:
+                        assert_not_reached();
+                }
+        }
+
+        s = NULL;
+        return 0;
+}
+
+static void socket_unwatch_fds(Socket *s) {
+        int r;
+
+        assert(s);
+
+        LIST_FOREACH(port, p, s->ports) {
+                if (p->fd < 0)
+                        continue;
+
+                if (!p->event_source)
+                        continue;
+
+                r = sd_event_source_set_enabled(p->event_source, SD_EVENT_OFF);
+                if (r < 0)
+                        log_unit_debug_errno(UNIT(s), r, "Failed to disable event source: %m");
+        }
+}
+
+static int socket_watch_fds(Socket *s) {
+        int r;
+
+        assert(s);
+
+        LIST_FOREACH(port, p, s->ports) {
+                if (p->fd < 0)
+                        continue;
+
+                if (p->event_source) {
+                        r = sd_event_source_set_enabled(p->event_source, SD_EVENT_ON);
+                        if (r < 0)
+                                goto fail;
+                } else {
+                        r = sd_event_add_io(UNIT(s)->manager->event, &p->event_source, p->fd, EPOLLIN, socket_dispatch_io, p);
+                        if (r < 0)
+                                goto fail;
+
+                        (void) sd_event_source_set_description(p->event_source, "socket-port-io");
+                }
+        }
+
+        return 0;
+
+fail:
+        log_unit_warning_errno(UNIT(s), r, "Failed to watch listening fds: %m");
+        socket_unwatch_fds(s);
+        return r;
+}
+
+enum {
+        SOCKET_OPEN_NONE,
+        SOCKET_OPEN_SOME,
+        SOCKET_OPEN_ALL,
+};
+
+static int socket_check_open(Socket *s) {
+        bool have_open = false, have_closed = false;
+
+        assert(s);
+
+        LIST_FOREACH(port, p, s->ports) {
+                if (p->fd < 0)
+                        have_closed = true;
+                else
+                        have_open = true;
+
+                if (have_open && have_closed)
+                        return SOCKET_OPEN_SOME;
+        }
+
+        if (have_open)
+                return SOCKET_OPEN_ALL;
+
+        return SOCKET_OPEN_NONE;
+}
+
+static void socket_set_state(Socket *s, SocketState state) {
+        SocketState old_state;
+        assert(s);
+
+        if (s->state != state)
+                bus_unit_send_pending_change_signal(UNIT(s), false);
+
+        old_state = s->state;
+        s->state = state;
+
+        if (!IN_SET(state,
+                    SOCKET_START_PRE,
+                    SOCKET_START_CHOWN,
+                    SOCKET_START_POST,
+                    SOCKET_STOP_PRE,
+                    SOCKET_STOP_PRE_SIGTERM,
+                    SOCKET_STOP_PRE_SIGKILL,
+                    SOCKET_STOP_POST,
+                    SOCKET_FINAL_SIGTERM,
+                    SOCKET_FINAL_SIGKILL,
+                    SOCKET_CLEANING)) {
+
+                s->timer_event_source = sd_event_source_disable_unref(s->timer_event_source);
+                socket_unwatch_control_pid(s);
+                s->control_command = NULL;
+                s->control_command_id = _SOCKET_EXEC_COMMAND_INVALID;
+        }
+
+        if (state != SOCKET_LISTENING)
+                socket_unwatch_fds(s);
+
+        if (!IN_SET(state,
+                    SOCKET_START_CHOWN,
+                    SOCKET_START_POST,
+                    SOCKET_LISTENING,
+                    SOCKET_RUNNING,
+                    SOCKET_STOP_PRE,
+                    SOCKET_STOP_PRE_SIGTERM,
+                    SOCKET_STOP_PRE_SIGKILL,
+                    SOCKET_CLEANING))
+                socket_close_fds(s);
+
+        if (state != old_state)
+                log_unit_debug(UNIT(s), "Changed %s -> %s", socket_state_to_string(old_state), socket_state_to_string(state));
+
+        unit_notify(UNIT(s), state_translation_table[old_state], state_translation_table[state], 0);
+}
+
+static int socket_coldplug(Unit *u) {
+        Socket *s = SOCKET(u);
+        int r;
+
+        assert(s);
+        assert(s->state == SOCKET_DEAD);
+
+        if (s->deserialized_state == s->state)
+                return 0;
+
+        if (s->control_pid > 0 &&
+            pid_is_unwaited(s->control_pid) &&
+            IN_SET(s->deserialized_state,
+                   SOCKET_START_PRE,
+                   SOCKET_START_CHOWN,
+                   SOCKET_START_POST,
+                   SOCKET_STOP_PRE,
+                   SOCKET_STOP_PRE_SIGTERM,
+                   SOCKET_STOP_PRE_SIGKILL,
+                   SOCKET_STOP_POST,
+                   SOCKET_FINAL_SIGTERM,
+                   SOCKET_FINAL_SIGKILL,
+                   SOCKET_CLEANING)) {
+
+                r = unit_watch_pid(UNIT(s), s->control_pid, false);
+                if (r < 0)
+                        return r;
+
+                r = socket_arm_timer(s, usec_add(u->state_change_timestamp.monotonic, s->timeout_usec));
+                if (r < 0)
+                        return r;
+        }
+
+        if (IN_SET(s->deserialized_state,
+                   SOCKET_START_CHOWN,
+                   SOCKET_START_POST,
+                   SOCKET_LISTENING,
+                   SOCKET_RUNNING)) {
+
+                /* Originally, we used to simply reopen all sockets here that we didn't have file descriptors
+                 * for. However, this is problematic, as we won't traverse through the SOCKET_START_CHOWN state for
+                 * them, and thus the UID/GID wouldn't be right. Hence, instead simply check if we have all fds open,
+                 * and if there's a mismatch, warn loudly. */
+
+                r = socket_check_open(s);
+                if (r == SOCKET_OPEN_NONE)
+                        log_unit_warning(UNIT(s),
+                                         "Socket unit configuration has changed while unit has been running, "
+                                         "no open socket file descriptor left. "
+                                         "The socket unit is not functional until restarted.");
+                else if (r == SOCKET_OPEN_SOME)
+                        log_unit_warning(UNIT(s),
+                                         "Socket unit configuration has changed while unit has been running, "
+                                         "and some socket file descriptors have not been opened yet. "
+                                         "The socket unit is not fully functional until restarted.");
+        }
+
+        if (s->deserialized_state == SOCKET_LISTENING) {
+                r = socket_watch_fds(s);
+                if (r < 0)
+                        return r;
+        }
+
+        if (!IN_SET(s->deserialized_state, SOCKET_DEAD, SOCKET_FAILED, SOCKET_CLEANING)) {
+                (void) unit_setup_dynamic_creds(u);
+                (void) unit_setup_exec_runtime(u);
+        }
+
+        socket_set_state(s, s->deserialized_state);
+        return 0;
+}
+
+static int socket_spawn(Socket *s, ExecCommand *c, pid_t *_pid) {
+
+        _cleanup_(exec_params_clear) ExecParameters exec_params = {
+                .flags     = EXEC_APPLY_SANDBOXING|EXEC_APPLY_CHROOT|EXEC_APPLY_TTY_STDIN,
+                .stdin_fd  = -1,
+                .stdout_fd = -1,
+                .stderr_fd = -1,
+                .exec_fd   = -1,
+        };
+        pid_t pid;
+        int r;
+
+        assert(s);
+        assert(c);
+        assert(_pid);
+
+        r = unit_prepare_exec(UNIT(s));
+        if (r < 0)
+                return r;
+
+        r = socket_arm_timer(s, usec_add(now(CLOCK_MONOTONIC), s->timeout_usec));
+        if (r < 0)
+                return r;
+
+        r = unit_set_exec_params(UNIT(s), &exec_params);
+        if (r < 0)
+                return r;
+
+        r = exec_spawn(UNIT(s),
+                       c,
+                       &s->exec_context,
+                       &exec_params,
+                       s->exec_runtime,
+                       &s->dynamic_creds,
+                       &pid);
+        if (r < 0)
+                return r;
+
+        r = unit_watch_pid(UNIT(s), pid, true);
+        if (r < 0)
+                return r;
+
+        *_pid = pid;
+
+        return 0;
+}
+
+static int socket_chown(Socket *s, pid_t *_pid) {
+        pid_t pid;
+        int r;
+
+        r = socket_arm_timer(s, usec_add(now(CLOCK_MONOTONIC), s->timeout_usec));
+        if (r < 0)
+                goto fail;
+
+        /* We have to resolve the user names out-of-process, hence
+         * let's fork here. It's messy, but well, what can we do? */
+
+        r = unit_fork_helper_process(UNIT(s), "(sd-chown)", &pid);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                uid_t uid = UID_INVALID;
+                gid_t gid = GID_INVALID;
+
+                /* Child */
+
+                if (!isempty(s->user)) {
+                        const char *user = s->user;
+
+                        r = get_user_creds(&user, &uid, &gid, NULL, NULL, 0);
+                        if (r < 0) {
+                                log_unit_error_errno(UNIT(s), r, "Failed to resolve user %s: %m", user);
+                                _exit(EXIT_USER);
+                        }
+                }
+
+                if (!isempty(s->group)) {
+                        const char *group = s->group;
+
+                        r = get_group_creds(&group, &gid, 0);
+                        if (r < 0) {
+                                log_unit_error_errno(UNIT(s), r, "Failed to resolve group %s: %m", group);
+                                _exit(EXIT_GROUP);
+                        }
+                }
+
+                LIST_FOREACH(port, p, s->ports) {
+                        const char *path = NULL;
+
+                        if (p->type == SOCKET_SOCKET)
+                                path = socket_address_get_path(&p->address);
+                        else if (p->type == SOCKET_FIFO)
+                                path = p->path;
+
+                        if (!path)
+                                continue;
+
+                        if (chown(path, uid, gid) < 0) {
+                                log_unit_error_errno(UNIT(s), errno, "Failed to chown(): %m");
+                                _exit(EXIT_CHOWN);
+                        }
+                }
+
+                _exit(EXIT_SUCCESS);
+        }
+
+        r = unit_watch_pid(UNIT(s), pid, true);
+        if (r < 0)
+                goto fail;
+
+        *_pid = pid;
+        return 0;
+
+fail:
+        s->timer_event_source = sd_event_source_disable_unref(s->timer_event_source);
+        return r;
+}
+
+static void socket_enter_dead(Socket *s, SocketResult f) {
+        assert(s);
+
+        if (s->result == SOCKET_SUCCESS)
+                s->result = f;
+
+        if (s->result == SOCKET_SUCCESS)
+                unit_log_success(UNIT(s));
+        else
+                unit_log_failure(UNIT(s), socket_result_to_string(s->result));
+
+        unit_warn_leftover_processes(UNIT(s), unit_log_leftover_process_stop);
+
+        socket_set_state(s, s->result != SOCKET_SUCCESS ? SOCKET_FAILED : SOCKET_DEAD);
+
+        s->exec_runtime = exec_runtime_unref(s->exec_runtime, true);
+
+        unit_destroy_runtime_data(UNIT(s), &s->exec_context);
+
+        unit_unref_uid_gid(UNIT(s), true);
+
+        dynamic_creds_destroy(&s->dynamic_creds);
+}
+
+static void socket_enter_signal(Socket *s, SocketState state, SocketResult f);
+
+static void socket_enter_stop_post(Socket *s, SocketResult f) {
+        int r;
+        assert(s);
+
+        if (s->result == SOCKET_SUCCESS)
+                s->result = f;
+
+        socket_unwatch_control_pid(s);
+        s->control_command_id = SOCKET_EXEC_STOP_POST;
+        s->control_command = s->exec_command[SOCKET_EXEC_STOP_POST];
+
+        if (s->control_command) {
+                r = socket_spawn(s, s->control_command, &s->control_pid);
+                if (r < 0)
+                        goto fail;
+
+                socket_set_state(s, SOCKET_STOP_POST);
+        } else
+                socket_enter_signal(s, SOCKET_FINAL_SIGTERM, SOCKET_SUCCESS);
+
+        return;
+
+fail:
+        log_unit_warning_errno(UNIT(s), r, "Failed to run 'stop-post' task: %m");
+        socket_enter_signal(s, SOCKET_FINAL_SIGTERM, SOCKET_FAILURE_RESOURCES);
+}
+
+static int state_to_kill_operation(Socket *s, SocketState state) {
+        if (state == SOCKET_STOP_PRE_SIGTERM && unit_has_job_type(UNIT(s), JOB_RESTART))
+                return KILL_RESTART;
+
+        if (state == SOCKET_FINAL_SIGTERM)
+                return KILL_TERMINATE;
+
+        return KILL_KILL;
+}
+
+static void socket_enter_signal(Socket *s, SocketState state, SocketResult f) {
+        int r;
+
+        assert(s);
+
+        if (s->result == SOCKET_SUCCESS)
+                s->result = f;
+
+        r = unit_kill_context(
+                        UNIT(s),
+                        &s->kill_context,
+                        state_to_kill_operation(s, state),
+                        -1,
+                        s->control_pid,
+                        false);
+        if (r < 0)
+                goto fail;
+
+        if (r > 0) {
+                r = socket_arm_timer(s, usec_add(now(CLOCK_MONOTONIC), s->timeout_usec));
+                if (r < 0)
+                        goto fail;
+
+                socket_set_state(s, state);
+        } else if (state == SOCKET_STOP_PRE_SIGTERM)
+                socket_enter_signal(s, SOCKET_STOP_PRE_SIGKILL, SOCKET_SUCCESS);
+        else if (state == SOCKET_STOP_PRE_SIGKILL)
+                socket_enter_stop_post(s, SOCKET_SUCCESS);
+        else if (state == SOCKET_FINAL_SIGTERM)
+                socket_enter_signal(s, SOCKET_FINAL_SIGKILL, SOCKET_SUCCESS);
+        else
+                socket_enter_dead(s, SOCKET_SUCCESS);
+
+        return;
+
+fail:
+        log_unit_warning_errno(UNIT(s), r, "Failed to kill processes: %m");
+
+        if (IN_SET(state, SOCKET_STOP_PRE_SIGTERM, SOCKET_STOP_PRE_SIGKILL))
+                socket_enter_stop_post(s, SOCKET_FAILURE_RESOURCES);
+        else
+                socket_enter_dead(s, SOCKET_FAILURE_RESOURCES);
+}
+
+static void socket_enter_stop_pre(Socket *s, SocketResult f) {
+        int r;
+        assert(s);
+
+        if (s->result == SOCKET_SUCCESS)
+                s->result = f;
+
+        socket_unwatch_control_pid(s);
+        s->control_command_id = SOCKET_EXEC_STOP_PRE;
+        s->control_command = s->exec_command[SOCKET_EXEC_STOP_PRE];
+
+        if (s->control_command) {
+                r = socket_spawn(s, s->control_command, &s->control_pid);
+                if (r < 0)
+                        goto fail;
+
+                socket_set_state(s, SOCKET_STOP_PRE);
+        } else
+                socket_enter_stop_post(s, SOCKET_SUCCESS);
+
+        return;
+
+fail:
+        log_unit_warning_errno(UNIT(s), r, "Failed to run 'stop-pre' task: %m");
+        socket_enter_stop_post(s, SOCKET_FAILURE_RESOURCES);
+}
+
+static void socket_enter_listening(Socket *s) {
+        int r;
+        assert(s);
+
+        if (!s->accept && s->flush_pending) {
+                log_unit_debug(UNIT(s), "Flushing socket before listening.");
+                flush_ports(s);
+        }
+
+        r = socket_watch_fds(s);
+        if (r < 0) {
+                log_unit_warning_errno(UNIT(s), r, "Failed to watch sockets: %m");
+                goto fail;
+        }
+
+        socket_set_state(s, SOCKET_LISTENING);
+        return;
+
+fail:
+        socket_enter_stop_pre(s, SOCKET_FAILURE_RESOURCES);
+}
+
+static void socket_enter_start_post(Socket *s) {
+        int r;
+        assert(s);
+
+        socket_unwatch_control_pid(s);
+        s->control_command_id = SOCKET_EXEC_START_POST;
+        s->control_command = s->exec_command[SOCKET_EXEC_START_POST];
+
+        if (s->control_command) {
+                r = socket_spawn(s, s->control_command, &s->control_pid);
+                if (r < 0) {
+                        log_unit_warning_errno(UNIT(s), r, "Failed to run 'start-post' task: %m");
+                        goto fail;
+                }
+
+                socket_set_state(s, SOCKET_START_POST);
+        } else
+                socket_enter_listening(s);
+
+        return;
+
+fail:
+        socket_enter_stop_pre(s, SOCKET_FAILURE_RESOURCES);
+}
+
+static void socket_enter_start_chown(Socket *s) {
+        int r;
+
+        assert(s);
+
+        r = socket_open_fds(s);
+        if (r < 0) {
+                log_unit_warning_errno(UNIT(s), r, "Failed to listen on sockets: %m");
+                goto fail;
+        }
+
+        if (!isempty(s->user) || !isempty(s->group)) {
+
+                socket_unwatch_control_pid(s);
+                s->control_command_id = SOCKET_EXEC_START_CHOWN;
+                s->control_command = NULL;
+
+                r = socket_chown(s, &s->control_pid);
+                if (r < 0) {
+                        log_unit_warning_errno(UNIT(s), r, "Failed to fork 'start-chown' task: %m");
+                        goto fail;
+                }
+
+                socket_set_state(s, SOCKET_START_CHOWN);
+        } else
+                socket_enter_start_post(s);
+
+        return;
+
+fail:
+        socket_enter_stop_pre(s, SOCKET_FAILURE_RESOURCES);
+}
+
+static void socket_enter_start_pre(Socket *s) {
+        int r;
+        assert(s);
+
+        socket_unwatch_control_pid(s);
+
+        unit_warn_leftover_processes(UNIT(s), unit_log_leftover_process_start);
+
+        s->control_command_id = SOCKET_EXEC_START_PRE;
+        s->control_command = s->exec_command[SOCKET_EXEC_START_PRE];
+
+        if (s->control_command) {
+                r = socket_spawn(s, s->control_command, &s->control_pid);
+                if (r < 0) {
+                        log_unit_warning_errno(UNIT(s), r, "Failed to run 'start-pre' task: %m");
+                        goto fail;
+                }
+
+                socket_set_state(s, SOCKET_START_PRE);
+        } else
+                socket_enter_start_chown(s);
+
+        return;
+
+fail:
+        socket_enter_dead(s, SOCKET_FAILURE_RESOURCES);
+}
+
+static void flush_ports(Socket *s) {
+        assert(s);
+
+        /* Flush all incoming traffic, regardless if actual bytes or new connections, so that this socket isn't busy
+         * anymore */
+
+        LIST_FOREACH(port, p, s->ports) {
+                if (p->fd < 0)
+                        continue;
+
+                (void) flush_accept(p->fd);
+                (void) flush_fd(p->fd);
+        }
+}
+
+static void socket_enter_running(Socket *s, int cfd_in) {
+        /* Note that this call takes possession of the connection fd passed. It either has to assign it
+         * somewhere or close it. */
+        _cleanup_close_ int cfd = cfd_in;
+
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        int r;
+
+        assert(s);
+
+        /* We don't take connections anymore if we are supposed to shut down anyway */
+        if (unit_stop_pending(UNIT(s))) {
+
+                log_unit_debug(UNIT(s), "Suppressing connection request since unit stop is scheduled.");
+
+                if (cfd >= 0)
+                        goto refuse;
+
+                flush_ports(s);
+                return;
+        }
+
+        if (!ratelimit_below(&s->trigger_limit)) {
+                log_unit_warning(UNIT(s), "Trigger limit hit, refusing further activation.");
+                socket_enter_stop_pre(s, SOCKET_FAILURE_TRIGGER_LIMIT_HIT);
+                goto refuse;
+        }
+
+        if (cfd < 0) {
+                bool pending = false;
+                Unit *other;
+
+                /* If there's already a start pending don't bother to do anything */
+                UNIT_FOREACH_DEPENDENCY(other, UNIT(s), UNIT_ATOM_TRIGGERS)
+                        if (unit_active_or_pending(other)) {
+                                pending = true;
+                                break;
+                        }
+
+                if (!pending) {
+                        if (!UNIT_ISSET(s->service)) {
+                                r = log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOENT),
+                                                         "Service to activate vanished, refusing activation.");
+                                goto fail;
+                        }
+
+                        r = manager_add_job(UNIT(s)->manager, JOB_START, UNIT_DEREF(s->service), JOB_REPLACE, NULL, &error, NULL);
+                        if (r < 0)
+                                goto fail;
+                }
+
+                socket_set_state(s, SOCKET_RUNNING);
+        } else {
+                _cleanup_(socket_peer_unrefp) SocketPeer *p = NULL;
+                Unit *service;
+
+                if (s->n_connections >= s->max_connections) {
+                        log_unit_warning(UNIT(s), "Too many incoming connections (%u), dropping connection.",
+                                         s->n_connections);
+                        goto refuse;
+                }
+
+                if (s->max_connections_per_source > 0) {
+                        r = socket_acquire_peer(s, cfd, &p);
+                        if (r < 0) {
+                                if (ERRNO_IS_DISCONNECT(r))
+                                        return;
+                                /* We didn't have enough resources to acquire peer information, let's fail. */
+                                goto fail;
+                        }
+                        if (r > 0 && p->n_ref > s->max_connections_per_source) {
+                                _cleanup_free_ char *t = NULL;
+
+                                (void) sockaddr_pretty(&p->peer.sa, p->peer_salen, true, false, &t);
+
+                                log_unit_warning(UNIT(s),
+                                                 "Too many incoming connections (%u) from source %s, dropping connection.",
+                                                 p->n_ref, strnull(t));
+                                goto refuse;
+                        }
+                }
+
+                r = socket_load_service_unit(s, cfd, &service);
+                if (ERRNO_IS_DISCONNECT(r))
+                        return;
+                if (r < 0)
+                        goto fail;
+
+                r = unit_add_two_dependencies(UNIT(s), UNIT_BEFORE, UNIT_TRIGGERS, service,
+                                              false, UNIT_DEPENDENCY_IMPLICIT);
+                if (r < 0)
+                        goto fail;
+
+                s->n_accepted++;
+
+                r = service_set_socket_fd(SERVICE(service), cfd, s, p, s->selinux_context_from_net);
+                if (ERRNO_IS_DISCONNECT(r))
+                        return;
+                if (r < 0)
+                        goto fail;
+
+                TAKE_FD(cfd); /* We passed ownership of the fd to the service now. Forget it here. */
+                s->n_connections++;
+
+                r = manager_add_job(UNIT(s)->manager, JOB_START, service, JOB_REPLACE, NULL, &error, NULL);
+                if (r < 0) {
+                        /* We failed to activate the new service, but it still exists. Let's make sure the
+                         * service closes and forgets the connection fd again, immediately. */
+                        service_close_socket_fd(SERVICE(service));
+                        goto fail;
+                }
+
+                /* Notify clients about changed counters */
+                unit_add_to_dbus_queue(UNIT(s));
+        }
+
+        TAKE_FD(cfd);
+        return;
+
+refuse:
+        s->n_refused++;
+        return;
+
+fail:
+        if (ERRNO_IS_RESOURCE(r))
+                log_unit_warning(UNIT(s), "Failed to queue service startup job: %s",
+                                 bus_error_message(&error, r));
+        else
+                log_unit_warning(UNIT(s), "Failed to queue service startup job (Maybe the service file is missing or not a %s unit?): %s",
+                                 cfd >= 0 ? "template" : "non-template",
+                                 bus_error_message(&error, r));
+
+        socket_enter_stop_pre(s, SOCKET_FAILURE_RESOURCES);
+}
+
+static void socket_run_next(Socket *s) {
+        int r;
+
+        assert(s);
+        assert(s->control_command);
+        assert(s->control_command->command_next);
+
+        socket_unwatch_control_pid(s);
+
+        s->control_command = s->control_command->command_next;
+
+        r = socket_spawn(s, s->control_command, &s->control_pid);
+        if (r < 0)
+                goto fail;
+
+        return;
+
+fail:
+        log_unit_warning_errno(UNIT(s), r, "Failed to run next task: %m");
+
+        if (s->state == SOCKET_START_POST)
+                socket_enter_stop_pre(s, SOCKET_FAILURE_RESOURCES);
+        else if (s->state == SOCKET_STOP_POST)
+                socket_enter_dead(s, SOCKET_FAILURE_RESOURCES);
+        else
+                socket_enter_signal(s, SOCKET_FINAL_SIGTERM, SOCKET_FAILURE_RESOURCES);
+}
+
+static int socket_start(Unit *u) {
+        Socket *s = SOCKET(u);
+        int r;
+
+        assert(s);
+
+        /* We cannot fulfill this request right now, try again later
+         * please! */
+        if (IN_SET(s->state,
+                   SOCKET_STOP_PRE,
+                   SOCKET_STOP_PRE_SIGKILL,
+                   SOCKET_STOP_PRE_SIGTERM,
+                   SOCKET_STOP_POST,
+                   SOCKET_FINAL_SIGTERM,
+                   SOCKET_FINAL_SIGKILL,
+                   SOCKET_CLEANING))
+                return -EAGAIN;
+
+        /* Already on it! */
+        if (IN_SET(s->state,
+                   SOCKET_START_PRE,
+                   SOCKET_START_CHOWN,
+                   SOCKET_START_POST))
+                return 0;
+
+        /* Cannot run this without the service being around */
+        if (UNIT_ISSET(s->service)) {
+                Service *service;
+
+                service = SERVICE(UNIT_DEREF(s->service));
+
+                if (UNIT(service)->load_state != UNIT_LOADED)
+                        return log_unit_error_errno(u, SYNTHETIC_ERRNO(ENOENT), "Socket service %s not loaded, refusing.", UNIT(service)->id);
+
+                /* If the service is already active we cannot start the
+                 * socket */
+                if (!IN_SET(service->state, SERVICE_DEAD, SERVICE_FAILED, SERVICE_AUTO_RESTART))
+                        return log_unit_error_errno(u, SYNTHETIC_ERRNO(EBUSY), "Socket service %s already active, refusing.", UNIT(service)->id);
+        }
+
+        assert(IN_SET(s->state, SOCKET_DEAD, SOCKET_FAILED));
+
+        r = unit_acquire_invocation_id(u);
+        if (r < 0)
+                return r;
+
+        s->result = SOCKET_SUCCESS;
+        exec_command_reset_status_list_array(s->exec_command, _SOCKET_EXEC_COMMAND_MAX);
+
+        u->reset_accounting = true;
+
+        socket_enter_start_pre(s);
+        return 1;
+}
+
+static int socket_stop(Unit *u) {
+        Socket *s = SOCKET(u);
+
+        assert(s);
+
+        /* Already on it */
+        if (IN_SET(s->state,
+                   SOCKET_STOP_PRE,
+                   SOCKET_STOP_PRE_SIGTERM,
+                   SOCKET_STOP_PRE_SIGKILL,
+                   SOCKET_STOP_POST,
+                   SOCKET_FINAL_SIGTERM,
+                   SOCKET_FINAL_SIGKILL))
+                return 0;
+
+        /* If there's already something running we go directly into
+         * kill mode. */
+        if (IN_SET(s->state,
+                   SOCKET_START_PRE,
+                   SOCKET_START_CHOWN,
+                   SOCKET_START_POST)) {
+                socket_enter_signal(s, SOCKET_STOP_PRE_SIGTERM, SOCKET_SUCCESS);
+                return -EAGAIN;
+        }
+
+        /* If we are currently cleaning, then abort it, brutally. */
+        if (s->state == SOCKET_CLEANING) {
+                socket_enter_signal(s, SOCKET_FINAL_SIGKILL, SOCKET_SUCCESS);
+                return 0;
+        }
+
+        assert(IN_SET(s->state, SOCKET_LISTENING, SOCKET_RUNNING));
+
+        socket_enter_stop_pre(s, SOCKET_SUCCESS);
+        return 1;
+}
+
+static int socket_serialize(Unit *u, FILE *f, FDSet *fds) {
+        Socket *s = SOCKET(u);
+        int r;
+
+        assert(u);
+        assert(f);
+        assert(fds);
+
+        (void) serialize_item(f, "state", socket_state_to_string(s->state));
+        (void) serialize_item(f, "result", socket_result_to_string(s->result));
+        (void) serialize_item_format(f, "n-accepted", "%u", s->n_accepted);
+        (void) serialize_item_format(f, "n-refused", "%u", s->n_refused);
+
+        if (s->control_pid > 0)
+                (void) serialize_item_format(f, "control-pid", PID_FMT, s->control_pid);
+
+        if (s->control_command_id >= 0)
+                (void) serialize_item(f, "control-command", socket_exec_command_to_string(s->control_command_id));
+
+        LIST_FOREACH(port, p, s->ports) {
+                int copy;
+
+                if (p->fd < 0)
+                        continue;
+
+                copy = fdset_put_dup(fds, p->fd);
+                if (copy < 0)
+                        return log_unit_warning_errno(u, copy, "Failed to serialize socket fd: %m");
+
+                if (p->type == SOCKET_SOCKET) {
+                        _cleanup_free_ char *t = NULL;
+
+                        r = socket_address_print(&p->address, &t);
+                        if (r < 0)
+                                return log_unit_error_errno(u, r, "Failed to format socket address: %m");
+
+                        if (socket_address_family(&p->address) == AF_NETLINK)
+                                (void) serialize_item_format(f, "netlink", "%i %s", copy, t);
+                        else
+                                (void) serialize_item_format(f, "socket", "%i %i %s", copy, p->address.type, t);
+                } else if (p->type == SOCKET_SPECIAL)
+                        (void) serialize_item_format(f, "special", "%i %s", copy, p->path);
+                else if (p->type == SOCKET_MQUEUE)
+                        (void) serialize_item_format(f, "mqueue", "%i %s", copy, p->path);
+                else if (p->type == SOCKET_USB_FUNCTION)
+                        (void) serialize_item_format(f, "ffs", "%i %s", copy, p->path);
+                else {
+                        assert(p->type == SOCKET_FIFO);
+                        (void) serialize_item_format(f, "fifo", "%i %s", copy, p->path);
+                }
+        }
+
+        return 0;
+}
+
+static int socket_deserialize_item(Unit *u, const char *key, const char *value, FDSet *fds) {
+        Socket *s = SOCKET(u);
+
+        assert(u);
+        assert(key);
+        assert(value);
+
+        if (streq(key, "state")) {
+                SocketState state;
+
+                state = socket_state_from_string(value);
+                if (state < 0)
+                        log_unit_debug(u, "Failed to parse state value: %s", value);
+                else
+                        s->deserialized_state = state;
+        } else if (streq(key, "result")) {
+                SocketResult f;
+
+                f = socket_result_from_string(value);
+                if (f < 0)
+                        log_unit_debug(u, "Failed to parse result value: %s", value);
+                else if (f != SOCKET_SUCCESS)
+                        s->result = f;
+
+        } else if (streq(key, "n-accepted")) {
+                unsigned k;
+
+                if (safe_atou(value, &k) < 0)
+                        log_unit_debug(u, "Failed to parse n-accepted value: %s", value);
+                else
+                        s->n_accepted += k;
+        } else if (streq(key, "n-refused")) {
+                unsigned k;
+
+                if (safe_atou(value, &k) < 0)
+                        log_unit_debug(u, "Failed to parse n-refused value: %s", value);
+                else
+                        s->n_refused += k;
+        } else if (streq(key, "control-pid")) {
+                pid_t pid;
+
+                if (parse_pid(value, &pid) < 0)
+                        log_unit_debug(u, "Failed to parse control-pid value: %s", value);
+                else
+                        s->control_pid = pid;
+        } else if (streq(key, "control-command")) {
+                SocketExecCommand id;
+
+                id = socket_exec_command_from_string(value);
+                if (id < 0)
+                        log_unit_debug(u, "Failed to parse exec-command value: %s", value);
+                else {
+                        s->control_command_id = id;
+                        s->control_command = s->exec_command[id];
+                }
+        } else if (streq(key, "fifo")) {
+                int fd, skip = 0;
+
+                if (sscanf(value, "%i %n", &fd, &skip) < 1 || fd < 0 || !fdset_contains(fds, fd))
+                        log_unit_debug(u, "Failed to parse fifo value: %s", value);
+                else {
+                        bool found = false;
+
+                        LIST_FOREACH(port, p, s->ports)
+                                if (p->fd < 0 &&
+                                    p->type == SOCKET_FIFO &&
+                                    path_equal_or_files_same(p->path, value+skip, 0)) {
+                                        p->fd = fdset_remove(fds, fd);
+                                        found = true;
+                                        break;
+                                }
+                        if (!found)
+                                log_unit_debug(u, "No matching fifo socket found: %s", value+skip);
+                }
+
+        } else if (streq(key, "special")) {
+                int fd, skip = 0;
+
+                if (sscanf(value, "%i %n", &fd, &skip) < 1 || fd < 0 || !fdset_contains(fds, fd))
+                        log_unit_debug(u, "Failed to parse special value: %s", value);
+                else {
+                        bool found = false;
+
+                        LIST_FOREACH(port, p, s->ports)
+                                if (p->fd < 0 &&
+                                    p->type == SOCKET_SPECIAL &&
+                                    path_equal_or_files_same(p->path, value+skip, 0)) {
+                                        p->fd = fdset_remove(fds, fd);
+                                        found = true;
+                                        break;
+                                }
+                        if (!found)
+                                log_unit_debug(u, "No matching special socket found: %s", value+skip);
+                }
+
+        } else if (streq(key, "mqueue")) {
+                int fd, skip = 0;
+
+                if (sscanf(value, "%i %n", &fd, &skip) < 1 || fd < 0 || !fdset_contains(fds, fd))
+                        log_unit_debug(u, "Failed to parse mqueue value: %s", value);
+                else {
+                        bool found = false;
+
+                        LIST_FOREACH(port, p, s->ports)
+                                if (p->fd < 0 &&
+                                    p->type == SOCKET_MQUEUE &&
+                                    streq(p->path, value+skip)) {
+                                        p->fd = fdset_remove(fds, fd);
+                                        found = true;
+                                        break;
+                                }
+                        if (!found)
+                                log_unit_debug(u, "No matching mqueue socket found: %s", value+skip);
+                }
+
+        } else if (streq(key, "socket")) {
+                int fd, type, skip = 0;
+
+                if (sscanf(value, "%i %i %n", &fd, &type, &skip) < 2 || fd < 0 || type < 0 || !fdset_contains(fds, fd))
+                        log_unit_debug(u, "Failed to parse socket value: %s", value);
+                else {
+                        bool found = false;
+
+                        LIST_FOREACH(port, p, s->ports)
+                                if (p->fd < 0 &&
+                                    socket_address_is(&p->address, value+skip, type)) {
+                                        p->fd = fdset_remove(fds, fd);
+                                        found = true;
+                                        break;
+                                }
+                        if (!found)
+                                log_unit_debug(u, "No matching %s socket found: %s",
+                                               socket_address_type_to_string(type), value+skip);
+                }
+
+        } else if (streq(key, "netlink")) {
+                int fd, skip = 0;
+
+                if (sscanf(value, "%i %n", &fd, &skip) < 1 || fd < 0 || !fdset_contains(fds, fd))
+                        log_unit_debug(u, "Failed to parse socket value: %s", value);
+                else {
+                        bool found = false;
+
+                        LIST_FOREACH(port, p, s->ports)
+                                if (p->fd < 0 &&
+                                    socket_address_is_netlink(&p->address, value+skip)) {
+                                        p->fd = fdset_remove(fds, fd);
+                                        found = true;
+                                        break;
+                                }
+                        if (!found)
+                                log_unit_debug(u, "No matching netlink socket found: %s", value+skip);
+                }
+
+        } else if (streq(key, "ffs")) {
+                int fd, skip = 0;
+
+                if (sscanf(value, "%i %n", &fd, &skip) < 1 || fd < 0 || !fdset_contains(fds, fd))
+                        log_unit_debug(u, "Failed to parse ffs value: %s", value);
+                else {
+                        bool found = false;
+
+                        LIST_FOREACH(port, p, s->ports)
+                                if (p->fd < 0 &&
+                                    p->type == SOCKET_USB_FUNCTION &&
+                                    path_equal_or_files_same(p->path, value+skip, 0)) {
+                                        p->fd = fdset_remove(fds, fd);
+                                        found = true;
+                                        break;
+                                }
+                        if (!found)
+                                log_unit_debug(u, "No matching ffs socket found: %s", value+skip);
+                }
+
+        } else
+                log_unit_debug(UNIT(s), "Unknown serialization key: %s", key);
+
+        return 0;
+}
+
+static void socket_distribute_fds(Unit *u, FDSet *fds) {
+        Socket *s = SOCKET(u);
+
+        assert(u);
+
+        LIST_FOREACH(port, p, s->ports) {
+                int fd;
+
+                if (p->type != SOCKET_SOCKET)
+                        continue;
+
+                if (p->fd >= 0)
+                        continue;
+
+                FDSET_FOREACH(fd, fds) {
+                        if (socket_address_matches_fd(&p->address, fd)) {
+                                p->fd = fdset_remove(fds, fd);
+                                s->deserialized_state = SOCKET_LISTENING;
+                                break;
+                        }
+                }
+        }
+}
+
+_pure_ static UnitActiveState socket_active_state(Unit *u) {
+        assert(u);
+
+        return state_translation_table[SOCKET(u)->state];
+}
+
+_pure_ static const char *socket_sub_state_to_string(Unit *u) {
+        assert(u);
+
+        return socket_state_to_string(SOCKET(u)->state);
+}
+
+const char* socket_port_type_to_string(SocketPort *p) {
+
+        assert(p);
+
+        switch (p->type) {
+
+        case SOCKET_SOCKET:
+
+                switch (p->address.type) {
+
+                case SOCK_STREAM:
+                        return "Stream";
+
+                case SOCK_DGRAM:
+                        return "Datagram";
+
+                case SOCK_SEQPACKET:
+                        return "SequentialPacket";
+
+                case SOCK_RAW:
+                        if (socket_address_family(&p->address) == AF_NETLINK)
+                                return "Netlink";
+
+                        _fallthrough_;
+                default:
+                        return NULL;
+                }
+
+        case SOCKET_SPECIAL:
+                return "Special";
+
+        case SOCKET_MQUEUE:
+                return "MessageQueue";
+
+        case SOCKET_FIFO:
+                return "FIFO";
+
+        case SOCKET_USB_FUNCTION:
+                return "USBFunction";
+
+        default:
+                return NULL;
+        }
+}
+
+SocketType socket_port_type_from_string(const char *s) {
+        assert(s);
+
+        if (STR_IN_SET(s, "Stream", "Datagram", "SequentialPacket", "Netlink"))
+                return SOCKET_SOCKET;
+        else if (streq(s, "Special"))
+                return SOCKET_SPECIAL;
+        else if (streq(s, "MessageQueue"))
+                return SOCKET_MQUEUE;
+        else if (streq(s, "FIFO"))
+                return SOCKET_FIFO;
+        else if (streq(s, "USBFunction"))
+                return SOCKET_USB_FUNCTION;
+        else
+                return _SOCKET_TYPE_INVALID;
+}
+
+_pure_ static bool socket_may_gc(Unit *u) {
+        Socket *s = SOCKET(u);
+
+        assert(u);
+
+        return s->n_connections == 0;
+}
+
+static int socket_accept_do(Socket *s, int fd) {
+        int cfd;
+
+        assert(s);
+        assert(fd >= 0);
+
+        cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
+        if (cfd < 0)
+                /* Convert transient network errors into clean and well-defined EAGAIN */
+                return ERRNO_IS_ACCEPT_AGAIN(errno) ? -EAGAIN : -errno;
+
+        return cfd;
+}
+
+static int socket_accept_in_cgroup(Socket *s, SocketPort *p, int fd) {
+        _cleanup_close_pair_ int pair[2] = { -1, -1 };
+        int cfd, r;
+        pid_t pid;
+
+        assert(s);
+        assert(p);
+        assert(fd >= 0);
+
+        /* Similar to socket_address_listen_in_cgroup(), but for accept() rather than socket(): make sure that any
+         * connection socket is also properly associated with the cgroup. */
+
+        if (!IN_SET(p->address.sockaddr.sa.sa_family, AF_INET, AF_INET6))
+                goto shortcut;
+
+        r = bpf_firewall_supported();
+        if (r < 0)
+                return r;
+        if (r == BPF_FIREWALL_UNSUPPORTED)
+                goto shortcut;
+
+        if (socketpair(AF_UNIX, SOCK_SEQPACKET|SOCK_CLOEXEC, 0, pair) < 0)
+                return log_unit_error_errno(UNIT(s), errno, "Failed to create communication channel: %m");
+
+        r = unit_fork_helper_process(UNIT(s), "(sd-accept)", &pid);
+        if (r < 0)
+                return log_unit_error_errno(UNIT(s), r, "Failed to fork off accept stub process: %m");
+        if (r == 0) {
+                /* Child */
+
+                pair[0] = safe_close(pair[0]);
+
+                cfd = socket_accept_do(s, fd);
+                if (cfd == -EAGAIN) /* spurious accept() */
+                        _exit(EXIT_SUCCESS);
+                if (cfd < 0) {
+                        log_unit_error_errno(UNIT(s), cfd, "Failed to accept connection socket: %m");
+                        _exit(EXIT_FAILURE);
+                }
+
+                r = send_one_fd(pair[1], cfd, 0);
+                if (r < 0) {
+                        log_unit_error_errno(UNIT(s), r, "Failed to send connection socket to parent: %m");
+                        _exit(EXIT_FAILURE);
+                }
+
+                _exit(EXIT_SUCCESS);
+        }
+
+        pair[1] = safe_close(pair[1]);
+        cfd = receive_one_fd(pair[0], 0);
+
+        /* We synchronously wait for the helper, as it shouldn't be slow */
+        r = wait_for_terminate_and_check("(sd-accept)", pid, WAIT_LOG_ABNORMAL);
+        if (r < 0) {
+                safe_close(cfd);
+                return r;
+        }
+
+        /* If we received no fd, we got EIO here. If this happens with a process exit code of EXIT_SUCCESS
+         * this is a spurious accept(), let's convert that back to EAGAIN here. */
+        if (cfd == -EIO)
+                return -EAGAIN;
+        if (cfd < 0)
+                return log_unit_error_errno(UNIT(s), cfd, "Failed to receive connection socket: %m");
+
+        return cfd;
+
+shortcut:
+        cfd = socket_accept_do(s, fd);
+        if (cfd == -EAGAIN) /* spurious accept(), skip it silently */
+                return -EAGAIN;
+        if (cfd < 0)
+                return log_unit_error_errno(UNIT(s), cfd, "Failed to accept connection socket: %m");
+
+        return cfd;
+}
+
+static int socket_dispatch_io(sd_event_source *source, int fd, uint32_t revents, void *userdata) {
+        SocketPort *p = ASSERT_PTR(userdata);
+        int cfd = -1;
+
+        assert(fd >= 0);
+
+        if (p->socket->state != SOCKET_LISTENING)
+                return 0;
+
+        log_unit_debug(UNIT(p->socket), "Incoming traffic");
+
+        if (revents != EPOLLIN) {
+                if (revents & EPOLLHUP)
+                        log_unit_error(UNIT(p->socket), "Got POLLHUP on a listening socket. The service probably invoked shutdown() on it, and should better not do that.");
+                else
+                        log_unit_error(UNIT(p->socket), "Got unexpected poll event (0x%x) on socket.", revents);
+                goto fail;
+        }
+
+        if (p->socket->accept &&
+            p->type == SOCKET_SOCKET &&
+            socket_address_can_accept(&p->address)) {
+
+                cfd = socket_accept_in_cgroup(p->socket, p, fd);
+                if (cfd == -EAGAIN) /* Spurious accept() */
+                        return 0;
+                if (cfd < 0)
+                        goto fail;
+
+                socket_apply_socket_options(p->socket, p, cfd);
+        }
+
+        socket_enter_running(p->socket, cfd);
+        return 0;
+
+fail:
+        socket_enter_stop_pre(p->socket, SOCKET_FAILURE_RESOURCES);
+        return 0;
+}
+
+static void socket_sigchld_event(Unit *u, pid_t pid, int code, int status) {
+        Socket *s = SOCKET(u);
+        SocketResult f;
+
+        assert(s);
+        assert(pid >= 0);
+
+        if (pid != s->control_pid)
+                return;
+
+        s->control_pid = 0;
+
+        if (is_clean_exit(code, status, EXIT_CLEAN_COMMAND, NULL))
+                f = SOCKET_SUCCESS;
+        else if (code == CLD_EXITED)
+                f = SOCKET_FAILURE_EXIT_CODE;
+        else if (code == CLD_KILLED)
+                f = SOCKET_FAILURE_SIGNAL;
+        else if (code == CLD_DUMPED)
+                f = SOCKET_FAILURE_CORE_DUMP;
+        else
+                assert_not_reached();
+
+        if (s->control_command) {
+                exec_status_exit(&s->control_command->exec_status, &s->exec_context, pid, code, status);
+
+                if (s->control_command->flags & EXEC_COMMAND_IGNORE_FAILURE)
+                        f = SOCKET_SUCCESS;
+        }
+
+        unit_log_process_exit(
+                        u,
+                        "Control process",
+                        socket_exec_command_to_string(s->control_command_id),
+                        f == SOCKET_SUCCESS,
+                        code, status);
+
+        if (s->result == SOCKET_SUCCESS)
+                s->result = f;
+
+        if (s->control_command &&
+            s->control_command->command_next &&
+            f == SOCKET_SUCCESS) {
+
+                log_unit_debug(u, "Running next command for state %s", socket_state_to_string(s->state));
+                socket_run_next(s);
+        } else {
+                s->control_command = NULL;
+                s->control_command_id = _SOCKET_EXEC_COMMAND_INVALID;
+
+                /* No further commands for this step, so let's figure
+                 * out what to do next */
+
+                log_unit_debug(u, "Got final SIGCHLD for state %s", socket_state_to_string(s->state));
+
+                switch (s->state) {
+
+                case SOCKET_START_PRE:
+                        if (f == SOCKET_SUCCESS)
+                                socket_enter_start_chown(s);
+                        else
+                                socket_enter_signal(s, SOCKET_FINAL_SIGTERM, f);
+                        break;
+
+                case SOCKET_START_CHOWN:
+                        if (f == SOCKET_SUCCESS)
+                                socket_enter_start_post(s);
+                        else
+                                socket_enter_stop_pre(s, f);
+                        break;
+
+                case SOCKET_START_POST:
+                        if (f == SOCKET_SUCCESS)
+                                socket_enter_listening(s);
+                        else
+                                socket_enter_stop_pre(s, f);
+                        break;
+
+                case SOCKET_STOP_PRE:
+                case SOCKET_STOP_PRE_SIGTERM:
+                case SOCKET_STOP_PRE_SIGKILL:
+                        socket_enter_stop_post(s, f);
+                        break;
+
+                case SOCKET_STOP_POST:
+                case SOCKET_FINAL_SIGTERM:
+                case SOCKET_FINAL_SIGKILL:
+                        socket_enter_dead(s, f);
+                        break;
+
+                case SOCKET_CLEANING:
+
+                        if (s->clean_result == SOCKET_SUCCESS)
+                                s->clean_result = f;
+
+                        socket_enter_dead(s, SOCKET_SUCCESS);
+                        break;
+
+                default:
+                        assert_not_reached();
+                }
+        }
+
+        /* Notify clients about changed exit status */
+        unit_add_to_dbus_queue(u);
+}
+
+static int socket_dispatch_timer(sd_event_source *source, usec_t usec, void *userdata) {
+        Socket *s = SOCKET(userdata);
+
+        assert(s);
+        assert(s->timer_event_source == source);
+
+        switch (s->state) {
+
+        case SOCKET_START_PRE:
+                log_unit_warning(UNIT(s), "Starting timed out. Terminating.");
+                socket_enter_signal(s, SOCKET_FINAL_SIGTERM, SOCKET_FAILURE_TIMEOUT);
+                break;
+
+        case SOCKET_START_CHOWN:
+        case SOCKET_START_POST:
+                log_unit_warning(UNIT(s), "Starting timed out. Stopping.");
+                socket_enter_stop_pre(s, SOCKET_FAILURE_TIMEOUT);
+                break;
+
+        case SOCKET_STOP_PRE:
+                log_unit_warning(UNIT(s), "Stopping timed out. Terminating.");
+                socket_enter_signal(s, SOCKET_STOP_PRE_SIGTERM, SOCKET_FAILURE_TIMEOUT);
+                break;
+
+        case SOCKET_STOP_PRE_SIGTERM:
+                if (s->kill_context.send_sigkill) {
+                        log_unit_warning(UNIT(s), "Stopping timed out. Killing.");
+                        socket_enter_signal(s, SOCKET_STOP_PRE_SIGKILL, SOCKET_FAILURE_TIMEOUT);
+                } else {
+                        log_unit_warning(UNIT(s), "Stopping timed out. Skipping SIGKILL. Ignoring.");
+                        socket_enter_stop_post(s, SOCKET_FAILURE_TIMEOUT);
+                }
+                break;
+
+        case SOCKET_STOP_PRE_SIGKILL:
+                log_unit_warning(UNIT(s), "Processes still around after SIGKILL. Ignoring.");
+                socket_enter_stop_post(s, SOCKET_FAILURE_TIMEOUT);
+                break;
+
+        case SOCKET_STOP_POST:
+                log_unit_warning(UNIT(s), "Stopping timed out (2). Terminating.");
+                socket_enter_signal(s, SOCKET_FINAL_SIGTERM, SOCKET_FAILURE_TIMEOUT);
+                break;
+
+        case SOCKET_FINAL_SIGTERM:
+                if (s->kill_context.send_sigkill) {
+                        log_unit_warning(UNIT(s), "Stopping timed out (2). Killing.");
+                        socket_enter_signal(s, SOCKET_FINAL_SIGKILL, SOCKET_FAILURE_TIMEOUT);
+                } else {
+                        log_unit_warning(UNIT(s), "Stopping timed out (2). Skipping SIGKILL. Ignoring.");
+                        socket_enter_dead(s, SOCKET_FAILURE_TIMEOUT);
+                }
+                break;
+
+        case SOCKET_FINAL_SIGKILL:
+                log_unit_warning(UNIT(s), "Still around after SIGKILL (2). Entering failed mode.");
+                socket_enter_dead(s, SOCKET_FAILURE_TIMEOUT);
+                break;
+
+        case SOCKET_CLEANING:
+                log_unit_warning(UNIT(s), "Cleaning timed out. killing.");
+
+                if (s->clean_result == SOCKET_SUCCESS)
+                        s->clean_result = SOCKET_FAILURE_TIMEOUT;
+
+                socket_enter_signal(s, SOCKET_FINAL_SIGKILL, 0);
+                break;
+
+        default:
+                assert_not_reached();
+        }
+
+        return 0;
+}
+
+int socket_collect_fds(Socket *s, int **fds) {
+        size_t k = 0, n = 0;
+        int *rfds;
+
+        assert(s);
+        assert(fds);
+
+        /* Called from the service code for requesting our fds */
+
+        LIST_FOREACH(port, p, s->ports) {
+                if (p->fd >= 0)
+                        n++;
+                n += p->n_auxiliary_fds;
+        }
+
+        if (n <= 0) {
+                *fds = NULL;
+                return 0;
+        }
+
+        rfds = new(int, n);
+        if (!rfds)
+                return -ENOMEM;
+
+        LIST_FOREACH(port, p, s->ports) {
+                if (p->fd >= 0)
+                        rfds[k++] = p->fd;
+                for (size_t i = 0; i < p->n_auxiliary_fds; ++i)
+                        rfds[k++] = p->auxiliary_fds[i];
+        }
+
+        assert(k == n);
+
+        *fds = rfds;
+        return (int) n;
+}
+
+static void socket_reset_failed(Unit *u) {
+        Socket *s = SOCKET(u);
+
+        assert(s);
+
+        if (s->state == SOCKET_FAILED)
+                socket_set_state(s, SOCKET_DEAD);
+
+        s->result = SOCKET_SUCCESS;
+        s->clean_result = SOCKET_SUCCESS;
+}
+
+void socket_connection_unref(Socket *s) {
+        assert(s);
+
+        /* The service is dead. Yay!
+         *
+         * This is strictly for one-instance-per-connection
+         * services. */
+
+        assert(s->n_connections > 0);
+        s->n_connections--;
+
+        log_unit_debug(UNIT(s), "One connection closed, %u left.", s->n_connections);
+}
+
+static void socket_trigger_notify(Unit *u, Unit *other) {
+        Socket *s = SOCKET(u);
+
+        assert(u);
+        assert(other);
+
+        /* Filter out invocations with bogus state */
+        assert(UNIT_IS_LOAD_COMPLETE(other->load_state));
+        assert(other->type == UNIT_SERVICE);
+
+        /* Don't propagate state changes from the service if we are already down */
+        if (!IN_SET(s->state, SOCKET_RUNNING, SOCKET_LISTENING))
+                return;
+
+        /* We don't care for the service state if we are in Accept=yes mode */
+        if (s->accept)
+                return;
+
+        /* Propagate start limit hit state */
+        if (other->start_limit_hit) {
+                socket_enter_stop_pre(s, SOCKET_FAILURE_SERVICE_START_LIMIT_HIT);
+                return;
+        }
+
+        /* Don't propagate anything if there's still a job queued */
+        if (other->job)
+                return;
+
+        if (IN_SET(SERVICE(other)->state,
+                   SERVICE_DEAD, SERVICE_FAILED,
+                   SERVICE_FINAL_SIGTERM, SERVICE_FINAL_SIGKILL,
+                   SERVICE_AUTO_RESTART))
+               socket_enter_listening(s);
+
+        if (SERVICE(other)->state == SERVICE_RUNNING)
+                socket_set_state(s, SOCKET_RUNNING);
+}
+
+static int socket_kill(Unit *u, KillWho who, int signo, sd_bus_error *error) {
+        return unit_kill_common(u, who, signo, -1, SOCKET(u)->control_pid, error);
+}
+
+static int socket_get_timeout(Unit *u, usec_t *timeout) {
+        Socket *s = SOCKET(u);
+        usec_t t;
+        int r;
+
+        if (!s->timer_event_source)
+                return 0;
+
+        r = sd_event_source_get_time(s->timer_event_source, &t);
+        if (r < 0)
+                return r;
+        if (t == USEC_INFINITY)
+                return 0;
+
+        *timeout = t;
+        return 1;
+}
+
+char *socket_fdname(Socket *s) {
+        assert(s);
+
+        /* Returns the name to use for $LISTEN_NAMES. If the user
+         * didn't specify anything specifically, use the socket unit's
+         * name as fallback. */
+
+        return s->fdname ?: UNIT(s)->id;
+}
+
+static int socket_control_pid(Unit *u) {
+        Socket *s = SOCKET(u);
+
+        assert(s);
+
+        return s->control_pid;
+}
+
+static int socket_clean(Unit *u, ExecCleanMask mask) {
+        _cleanup_strv_free_ char **l = NULL;
+        Socket *s = SOCKET(u);
+        int r;
+
+        assert(s);
+        assert(mask != 0);
+
+        if (s->state != SOCKET_DEAD)
+                return -EBUSY;
+
+        r = exec_context_get_clean_directories(&s->exec_context, u->manager->prefix, mask, &l);
+        if (r < 0)
+                return r;
+
+        if (strv_isempty(l))
+                return -EUNATCH;
+
+        socket_unwatch_control_pid(s);
+        s->clean_result = SOCKET_SUCCESS;
+        s->control_command = NULL;
+        s->control_command_id = _SOCKET_EXEC_COMMAND_INVALID;
+
+        r = socket_arm_timer(s, usec_add(now(CLOCK_MONOTONIC), s->exec_context.timeout_clean_usec));
+        if (r < 0)
+                goto fail;
+
+        r = unit_fork_and_watch_rm_rf(u, l, &s->control_pid);
+        if (r < 0)
+                goto fail;
+
+        socket_set_state(s, SOCKET_CLEANING);
+
+        return 0;
+
+fail:
+        log_unit_warning_errno(u, r, "Failed to initiate cleaning: %m");
+        s->clean_result = SOCKET_FAILURE_RESOURCES;
+        s->timer_event_source = sd_event_source_disable_unref(s->timer_event_source);
+        return r;
+}
+
+static int socket_can_clean(Unit *u, ExecCleanMask *ret) {
+        Socket *s = SOCKET(u);
+
+        assert(s);
+
+        return exec_context_get_clean_mask(&s->exec_context, ret);
+}
+
+static int socket_can_start(Unit *u) {
+        Socket *s = SOCKET(u);
+        int r;
+
+        assert(s);
+
+        r = unit_test_start_limit(u);
+        if (r < 0) {
+                socket_enter_dead(s, SOCKET_FAILURE_START_LIMIT_HIT);
+                return r;
+        }
+
+        return 1;
+}
+
+static const char* const socket_exec_command_table[_SOCKET_EXEC_COMMAND_MAX] = {
+        [SOCKET_EXEC_START_PRE]   = "ExecStartPre",
+        [SOCKET_EXEC_START_CHOWN] = "ExecStartChown",
+        [SOCKET_EXEC_START_POST]  = "ExecStartPost",
+        [SOCKET_EXEC_STOP_PRE]    = "ExecStopPre",
+        [SOCKET_EXEC_STOP_POST]   = "ExecStopPost"
+};
+
+DEFINE_STRING_TABLE_LOOKUP(socket_exec_command, SocketExecCommand);
+
+static const char* const socket_result_table[_SOCKET_RESULT_MAX] = {
+        [SOCKET_SUCCESS]                         = "success",
+        [SOCKET_FAILURE_RESOURCES]               = "resources",
+        [SOCKET_FAILURE_TIMEOUT]                 = "timeout",
+        [SOCKET_FAILURE_EXIT_CODE]               = "exit-code",
+        [SOCKET_FAILURE_SIGNAL]                  = "signal",
+        [SOCKET_FAILURE_CORE_DUMP]               = "core-dump",
+        [SOCKET_FAILURE_START_LIMIT_HIT]         = "start-limit-hit",
+        [SOCKET_FAILURE_TRIGGER_LIMIT_HIT]       = "trigger-limit-hit",
+        [SOCKET_FAILURE_SERVICE_START_LIMIT_HIT] = "service-start-limit-hit"
+};
+
+DEFINE_STRING_TABLE_LOOKUP(socket_result, SocketResult);
+
+static const char* const socket_timestamping_table[_SOCKET_TIMESTAMPING_MAX] = {
+        [SOCKET_TIMESTAMPING_OFF] = "off",
+        [SOCKET_TIMESTAMPING_US]  = "us",
+        [SOCKET_TIMESTAMPING_NS]  = "ns",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(socket_timestamping, SocketTimestamping);
+
+SocketTimestamping socket_timestamping_from_string_harder(const char *p) {
+        SocketTimestamping t;
+        int r;
+
+        if (!p)
+                return _SOCKET_TIMESTAMPING_INVALID;
+
+        t = socket_timestamping_from_string(p);
+        if (t >= 0)
+                return t;
+
+        /* Let's alternatively support the various other aliases parse_time() accepts for ns and µs here,
+         * too. */
+        if (streq(p, "nsec"))
+                return SOCKET_TIMESTAMPING_NS;
+        if (STR_IN_SET(p, "usec", "µs", "μs")) /* Accept both small greek letter mu + micro sign unicode codepoints */
+                return SOCKET_TIMESTAMPING_US;
+
+        r = parse_boolean(p);
+        if (r < 0)
+                return _SOCKET_TIMESTAMPING_INVALID;
+
+        return r ? SOCKET_TIMESTAMPING_NS : SOCKET_TIMESTAMPING_OFF; /* If boolean yes, default to ns accuracy */
+}
+
+const UnitVTable socket_vtable = {
+        .object_size = sizeof(Socket),
+        .exec_context_offset = offsetof(Socket, exec_context),
+        .cgroup_context_offset = offsetof(Socket, cgroup_context),
+        .kill_context_offset = offsetof(Socket, kill_context),
+        .exec_runtime_offset = offsetof(Socket, exec_runtime),
+        .dynamic_creds_offset = offsetof(Socket, dynamic_creds),
+
+        .sections =
+                "Unit\0"
+                "Socket\0"
+                "Install\0",
+        .private_section = "Socket",
+
+        .can_transient = true,
+        .can_trigger = true,
+        .can_fail = true,
+
+        .init = socket_init,
+        .done = socket_done,
+        .load = socket_load,
+
+        .coldplug = socket_coldplug,
+
+        .dump = socket_dump,
+
+        .start = socket_start,
+        .stop = socket_stop,
+
+        .kill = socket_kill,
+        .clean = socket_clean,
+        .can_clean = socket_can_clean,
+
+        .get_timeout = socket_get_timeout,
+
+        .serialize = socket_serialize,
+        .deserialize_item = socket_deserialize_item,
+        .distribute_fds = socket_distribute_fds,
+
+        .active_state = socket_active_state,
+        .sub_state_to_string = socket_sub_state_to_string,
+
+        .will_restart = unit_will_restart_default,
+
+        .may_gc = socket_may_gc,
+
+        .sigchld_event = socket_sigchld_event,
+
+        .trigger_notify = socket_trigger_notify,
+
+        .reset_failed = socket_reset_failed,
+
+        .control_pid = socket_control_pid,
+
+        .bus_set_property = bus_socket_set_property,
+        .bus_commit_properties = bus_socket_commit_properties,
+
+        .status_message_formats = {
+                .finished_start_job = {
+                        [JOB_DONE]       = "Listening on %s.",
+                        [JOB_FAILED]     = "Failed to listen on %s.",
+                        [JOB_TIMEOUT]    = "Timed out starting %s.",
+                },
+                .finished_stop_job = {
+                        [JOB_DONE]       = "Closed %s.",
+                        [JOB_FAILED]     = "Failed stopping %s.",
+                        [JOB_TIMEOUT]    = "Timed out stopping %s.",
+                },
+        },
+
+        .can_start = socket_can_start,
+};