socket: optionally call accept() for incoming connections and spawn one service instance per connection

13 files changed, 403 insertions, 68 deletions

diff --git a/device.c b/device.c
index 1c4c32931c..1a4edd29a7 100644
--- a/device.c
+++ b/device.c
@@ -415,21 +415,21 @@ static int device_enumerate(Manager *m) {
         if (epoll_ctl(m->epoll_fd, EPOLL_CTL_ADD, m->udev_watch.fd, &ev) < 0)
                 return -errno;
 
-        /* if (!(e = udev_enumerate_new(m->udev))) { */
-        /*         r = -ENOMEM; */
-        /*         goto fail; */
-        /* } */
+        if (!(e = udev_enumerate_new(m->udev))) {
+                r = -ENOMEM;
+                goto fail;
+        }
 
-        /* if (udev_enumerate_scan_devices(e) < 0) { */
-        /*         r = -EIO; */
-        /*         goto fail; */
-        /* } */
+        if (udev_enumerate_scan_devices(e) < 0) {
+                r = -EIO;
+                goto fail;
+        }
 
-        /* first = udev_enumerate_get_list_entry(e); */
-        /* udev_list_entry_foreach(item, first) */
-        /*         device_process_path(m, udev_list_entry_get_name(item), false); */
+        first = udev_enumerate_get_list_entry(e);
+        udev_list_entry_foreach(item, first)
+                device_process_path(m, udev_list_entry_get_name(item), false);
 
-        /* udev_enumerate_unref(e); */
+        udev_enumerate_unref(e);
         return 0;
 
 fail:
diff --git a/execute.c b/execute.c
index 9b407258ff..dfedb31a53 100644
--- a/execute.c
+++ b/execute.c
@@ -222,10 +222,41 @@ static bool is_terminal_input(ExecInput i) {
                 i == EXEC_INPUT_TTY_FAIL;
 }
 
-static int setup_input(const ExecContext *context) {
+static int fixup_input(const ExecContext *context, int socket_fd) {
         assert(context);
 
-        switch (context->std_input) {
+        if (socket_fd < 0 && context->std_input == EXEC_INPUT_SOCKET)
+                return EXEC_INPUT_NULL;
+
+        return context->std_input;
+}
+
+static int fixup_output(const ExecContext *context, int socket_fd) {
+        assert(context);
+
+        if (socket_fd < 0 && context->std_output == EXEC_OUTPUT_SOCKET)
+                return EXEC_OUTPUT_INHERIT;
+
+        return context->std_output;
+}
+
+static int fixup_error(const ExecContext *context, int socket_fd) {
+        assert(context);
+
+        if (socket_fd < 0 && context->std_error == EXEC_OUTPUT_SOCKET)
+                return EXEC_OUTPUT_INHERIT;
+
+        return context->std_error;
+}
+
+static int setup_input(const ExecContext *context, int socket_fd) {
+        ExecInput i;
+
+        assert(context);
+
+        i = fixup_input(context, socket_fd);
+
+        switch (i) {
 
         case EXEC_INPUT_NULL:
                 return open_null_as(O_RDONLY, STDIN_FILENO);
@@ -237,8 +268,8 @@ static int setup_input(const ExecContext *context) {
 
                 if ((fd = acquire_terminal(
                                      tty_path(context),
-                                     context->std_input == EXEC_INPUT_TTY_FAIL,
-                                     context->std_input == EXEC_INPUT_TTY_FORCE)) < 0)
+                                     i == EXEC_INPUT_TTY_FAIL,
+                                     i == EXEC_INPUT_TTY_FORCE)) < 0)
                         return fd;
 
                 if (fd != STDIN_FILENO) {
@@ -250,72 +281,90 @@ static int setup_input(const ExecContext *context) {
                 return r;
         }
 
+        case EXEC_INPUT_SOCKET:
+                return dup2(socket_fd, STDIN_FILENO) < 0 ? -errno : STDIN_FILENO;
+
         default:
                 assert_not_reached("Unknown input type");
         }
 }
 
-static int setup_output(const ExecContext *context, const char *ident) {
+static int setup_output(const ExecContext *context, int socket_fd, const char *ident) {
+        ExecOutput o;
+        ExecInput i;
+
         assert(context);
         assert(ident);
 
+        i = fixup_input(context, socket_fd);
+        o = fixup_output(context, socket_fd);
+
         /* This expects the input is already set up */
 
-        switch (context->std_output) {
+        switch (o) {
 
         case EXEC_OUTPUT_INHERIT:
 
                 /* If the input is connected to a terminal, inherit that... */
-                if (is_terminal_input(context->std_input))
+                if (is_terminal_input(i) || i == EXEC_INPUT_SOCKET)
                         return dup2(STDIN_FILENO, STDOUT_FILENO) < 0 ? -errno : STDOUT_FILENO;
 
-                return 0;
+                return STDIN_FILENO;
 
         case EXEC_OUTPUT_NULL:
                 return open_null_as(O_WRONLY, STDOUT_FILENO);
 
-        case EXEC_OUTPUT_TTY: {
-                if (is_terminal_input(context->std_input))
+        case EXEC_OUTPUT_TTY:
+                if (is_terminal_input(i))
                         return dup2(STDIN_FILENO, STDOUT_FILENO) < 0 ? -errno : STDOUT_FILENO;
 
                 /* We don't reset the terminal if this is just about output */
                 return open_terminal_as(tty_path(context), O_WRONLY, STDOUT_FILENO);
-        }
 
         case EXEC_OUTPUT_SYSLOG:
         case EXEC_OUTPUT_KERNEL:
-                return connect_logger_as(context, context->std_output, ident, STDOUT_FILENO);
+                return connect_logger_as(context, o, ident, STDOUT_FILENO);
+
+        case EXEC_OUTPUT_SOCKET:
+                assert(socket_fd >= 0);
+                return dup2(socket_fd, STDOUT_FILENO) < 0 ? -errno : STDOUT_FILENO;
 
         default:
                 assert_not_reached("Unknown output type");
         }
 }
 
-static int setup_error(const ExecContext *context, const char *ident) {
+static int setup_error(const ExecContext *context, int socket_fd, const char *ident) {
+        ExecOutput o, e;
+        ExecInput i;
+
         assert(context);
         assert(ident);
 
+        i = fixup_input(context, socket_fd);
+        o = fixup_output(context, socket_fd);
+        e = fixup_error(context, socket_fd);
+
         /* This expects the input and output are already set up */
 
         /* Don't change the stderr file descriptor if we inherit all
          * the way and are not on a tty */
-        if (context->std_error == EXEC_OUTPUT_INHERIT &&
-            context->std_output == EXEC_OUTPUT_INHERIT &&
-            !is_terminal_input(context->std_input))
+        if (e == EXEC_OUTPUT_INHERIT &&
+            o == EXEC_OUTPUT_INHERIT &&
+            !is_terminal_input(i))
                 return STDERR_FILENO;
 
         /* Duplicate form stdout if possible */
-        if (context->std_error == context->std_output ||
-            context->std_error == EXEC_OUTPUT_INHERIT)
+        if (e == o || e == EXEC_OUTPUT_INHERIT)
                 return dup2(STDOUT_FILENO, STDERR_FILENO) < 0 ? -errno : STDERR_FILENO;
 
-        switch (context->std_error) {
+        switch (e) {
 
         case EXEC_OUTPUT_NULL:
                 return open_null_as(O_WRONLY, STDERR_FILENO);
 
         case EXEC_OUTPUT_TTY:
-                if (is_terminal_input(context->std_input))
+                if (is_terminal_input(i))
                         return dup2(STDIN_FILENO, STDERR_FILENO) < 0 ? -errno : STDERR_FILENO;
 
                 /* We don't reset the terminal if this is just about output */
@@ -323,7 +372,11 @@ static int setup_error(const ExecContext *context, const char *ident) {
 
         case EXEC_OUTPUT_SYSLOG:
         case EXEC_OUTPUT_KERNEL:
-                return connect_logger_as(context, context->std_error, ident, STDERR_FILENO);
+                return connect_logger_as(context, e, ident, STDERR_FILENO);
+
+        case EXEC_OUTPUT_SOCKET:
+                assert(socket_fd >= 0);
+                return dup2(socket_fd, STDERR_FILENO) < 0 ? -errno : STDERR_FILENO;
 
         default:
                 assert_not_reached("Unknown error type");
@@ -677,12 +730,27 @@ int exec_spawn(ExecCommand *command,
         pid_t pid;
         int r;
         char *line;
+        int socket_fd;
 
         assert(command);
         assert(context);
         assert(ret);
         assert(fds || n_fds <= 0);
 
+        if (context->std_input == EXEC_INPUT_SOCKET ||
+            context->std_output == EXEC_OUTPUT_SOCKET ||
+            context->std_error == EXEC_OUTPUT_SOCKET) {
+
+                if (n_fds != 1)
+                        return -EINVAL;
+
+                socket_fd = fds[0];
+
+                fds = NULL;
+                n_fds = 0;
+        } else
+                socket_fd = -1;
+
         if (!argv)
                 argv = command->argv;
 
@@ -760,18 +828,18 @@ int exec_spawn(ExecCommand *command,
                 }
 
                 if (!keep_stdin)
-                        if (setup_input(context) < 0) {
+                        if (setup_input(context, socket_fd) < 0) {
                                 r = EXIT_STDIN;
                                 goto fail;
                         }
 
                 if (!keep_stdout)
-                        if (setup_output(context, file_name_from_path(command->path)) < 0) {
+                        if (setup_output(context, socket_fd, file_name_from_path(command->path)) < 0) {
                                 r = EXIT_STDOUT;
                                 goto fail;
                         }
 
-                if (setup_error(context, file_name_from_path(command->path)) < 0) {
+                if (setup_error(context, socket_fd, file_name_from_path(command->path)) < 0) {
                         r = EXIT_STDERR;
                         goto fail;
                 }
@@ -1501,7 +1569,8 @@ static const char* const exec_input_table[_EXEC_INPUT_MAX] = {
         [EXEC_INPUT_NULL] = "null",
         [EXEC_INPUT_TTY] = "tty",
         [EXEC_INPUT_TTY_FORCE] = "tty-force",
-        [EXEC_INPUT_TTY_FAIL] = "tty-fail"
+        [EXEC_INPUT_TTY_FAIL] = "tty-fail",
+        [EXEC_INPUT_SOCKET] = "socket"
 };
 
 static const char* const exec_output_table[_EXEC_OUTPUT_MAX] = {
@@ -1509,7 +1578,8 @@ static const char* const exec_output_table[_EXEC_OUTPUT_MAX] = {
         [EXEC_OUTPUT_NULL] = "null",
         [EXEC_OUTPUT_TTY] = "tty",
         [EXEC_OUTPUT_SYSLOG] = "syslog",
-        [EXEC_OUTPUT_KERNEL] = "kernel"
+        [EXEC_OUTPUT_KERNEL] = "kernel",
+        [EXEC_OUTPUT_SOCKET] = "socket"
 };
 
 DEFINE_STRING_TABLE_LOOKUP(exec_output, ExecOutput);
diff --git a/execute.h b/execute.h
index 6d877ff7b7..135c8bab5f 100644
--- a/execute.h
+++ b/execute.h
@@ -46,6 +46,7 @@ typedef enum ExecInput {
         EXEC_INPUT_TTY,
         EXEC_INPUT_TTY_FORCE,
         EXEC_INPUT_TTY_FAIL,
+        EXEC_INPUT_SOCKET,
         _EXEC_INPUT_MAX,
         _EXEC_INPUT_INVALID = -1
 } ExecInput;
@@ -56,6 +57,7 @@ typedef enum ExecOutput {
         EXEC_OUTPUT_TTY,
         EXEC_OUTPUT_SYSLOG,
         EXEC_OUTPUT_KERNEL,
+        EXEC_OUTPUT_SOCKET,
         _EXEC_OUTPUT_MAX,
         _EXEC_OUTPUT_INVALID = -1
 } ExecOutput;
diff --git a/load-fragment.c b/load-fragment.c
index 5093c6dea9..5e98ae8324 100644
--- a/load-fragment.c
+++ b/load-fragment.c
@@ -1199,6 +1199,7 @@ static int load_from_path(Unit *u, const char *path) {
                 { "DirectoryMode",          config_parse_mode,            &u->socket.directory_mode,                       "Socket"  },
                 { "SocketMode",             config_parse_mode,            &u->socket.socket_mode,                          "Socket"  },
                 { "KillMode",               config_parse_kill_mode,       &u->socket.kill_mode,                            "Socket"  },
+                { "Accept",                 config_parse_bool,            &u->socket.accept,                               "Socket"  },
                 EXEC_CONTEXT_CONFIG_ITEMS(u->socket.exec_context, "Socket"),
 
                 { "What",                   config_parse_string,          &u->mount.parameters_fragment.what,              "Mount"   },
diff --git a/manager.h b/manager.h
index a2b7b7ef8d..ae9cd9fe93 100644
--- a/manager.h
+++ b/manager.h
@@ -59,6 +59,7 @@ struct Watch {
                 union Unit *unit;
                 DBusWatch *bus_watch;
                 DBusTimeout *bus_timeout;
+                bool socket_accept;
         } data;
 };
 
diff --git a/service.c b/service.c
index 9ab8ec1a43..96e9d83ad9 100644
--- a/service.c
+++ b/service.c
@@ -85,6 +85,16 @@ static void service_unwatch_main_pid(Service *s) {
         s->main_pid = 0;
 }
 
+static void service_close_socket_fd(Service *s) {
+        assert(s);
+
+        if (s->socket_fd < 0)
+                return;
+
+        close_nointr_nofail(s->socket_fd);
+        s->socket_fd = -1;
+}
+
 static void service_done(Unit *u) {
         Service *s = SERVICE(u);
 
@@ -108,6 +118,8 @@ static void service_done(Unit *u) {
         service_unwatch_main_pid(s);
         service_unwatch_control_pid(s);
 
+        service_close_socket_fd(s);
+
         unit_unwatch_timer(u, &s->timer_watch);
 }
 
@@ -728,6 +740,8 @@ static void service_init(Unit *u) {
         s->main_pid_known = false;
         s->failure = false;
 
+        s->socket_fd = -1;
+
         RATELIMIT_INIT(s->ratelimit, 10*USEC_PER_SEC, 5);
 }
 
@@ -944,7 +958,6 @@ fail:
         return r;
 }
 
-
 static int service_notify_sockets_dead(Service *s) {
         Iterator i;
         Set *set;
@@ -954,7 +967,6 @@ static int service_notify_sockets_dead(Service *s) {
         assert(s);
 
         /* Notifies all our sockets when we die */
-
         if ((r = service_get_sockets(s, &set)) < 0)
                 return r;
 
@@ -1020,6 +1032,11 @@ static void service_set_state(Service *s, ServiceState state) {
             state == SERVICE_AUTO_RESTART)
                 service_notify_sockets_dead(s);
 
+        if (state != SERVICE_START_PRE &&
+            state != SERVICE_START &&
+            !(state == SERVICE_DEAD && UNIT(s)->meta.job))
+                service_close_socket_fd(s);
+
         if (old_state != state)
                 log_debug("%s changed %s → %s", UNIT(s)->meta.id, service_state_to_string(old_state), service_state_to_string(state));
 
@@ -1106,9 +1123,13 @@ static int service_spawn(
         assert(c);
         assert(_pid);
 
-        if (pass_fds)
-                if ((r = service_collect_fds(s, &fds, &n_fds)) < 0)
+        if (pass_fds) {
+                if (s->socket_fd >= 0) {
+                        fds = &s->socket_fd;
+                        n_fds = 1;
+                } else if ((r = service_collect_fds(s, &fds, &n_fds)) < 0)
                         goto fail;
+        }
 
         if (timeout) {
                 if ((r = unit_watch_timer(UNIT(s), s->timeout_usec, &s->timer_watch)) < 0)
@@ -1135,11 +1156,17 @@ static int service_spawn(
         if (r < 0)
                 goto fail;
 
+        if (fds) {
+                if (s->socket_fd >= 0)
+                        service_close_socket_fd(s);
+                else
+                        free(fds);
+        }
+
         if ((r = unit_watch_pid(UNIT(s), pid)) < 0)
                 /* FIXME: we need to do something here */
                 goto fail;
 
-        free(fds);
         *_pid = pid;
 
         return 0;
@@ -2019,6 +2046,27 @@ finish:
         return r;
 }
 
+int service_set_socket_fd(Service *s, int fd) {
+        assert(s);
+        assert(fd >= 0);
+
+        /* This is called by the socket code when instantiating a new
+         * service for a stream socket and the socket needs to be
+         * configured. */
+
+        if (UNIT(s)->meta.load_state != UNIT_LOADED)
+                return -EINVAL;
+
+        if (s->socket_fd >= 0)
+                return -EBUSY;
+
+        if (s->state != SERVICE_DEAD)
+                return -EAGAIN;
+
+        s->socket_fd = fd;
+        return 0;
+}
+
 static const char* const service_state_table[_SERVICE_STATE_MAX] = {
         [SERVICE_DEAD] = "dead",
         [SERVICE_START_PRE] = "start-pre",
diff --git a/service.h b/service.h
index f357fc857e..5ddc180423 100644
--- a/service.h
+++ b/service.h
@@ -112,11 +112,15 @@ struct Service {
 
         RateLimit ratelimit;
 
+        int socket_fd;
+
         Watch timer_watch;
 };
 
 extern const UnitVTable service_vtable;
 
+int service_set_socket_fd(Service *s, int fd);
+
 const char* service_state_to_string(ServiceState i);
 ServiceState service_state_from_string(const char *s);
 
diff --git a/socket-util.c b/socket-util.c
index 96567c6d81..cd5ab82a23 100644
--- a/socket-util.c
+++ b/socket-util.c
@@ -316,7 +316,7 @@ int socket_address_listen(
         if ((r = socket_address_verify(a)) < 0)
                 return r;
 
-        if ((fd = socket(socket_address_family(a), a->type | SOCK_NONBLOCK | SOCK_CLOEXEC, 0)) < 0)
+        if ((fd = socket(socket_address_family(a), a->type | SOCK_NONBLOCK, 0)) < 0)
                 return -errno;
 
         if (socket_address_family(a) == AF_INET6 && only != SOCKET_ADDRESS_DEFAULT) {
@@ -373,3 +373,11 @@ fail:
         close_nointr(fd);
         return r;
 }
+
+bool socket_address_can_accept(const SocketAddress *a) {
+        assert(a);
+
+        return
+                a->type == SOCK_STREAM ||
+                a->type == SOCK_SEQPACKET;
+}
diff --git a/socket-util.h b/socket-util.h
index 62a48ac35a..e6e1b30b53 100644
--- a/socket-util.h
+++ b/socket-util.h
@@ -59,6 +59,8 @@ int socket_address_parse(SocketAddress *a, const char *s);
 int socket_address_print(const SocketAddress *a, char **p);
 int socket_address_verify(const SocketAddress *a);
 
+bool socket_address_can_accept(const SocketAddress *a);
+
 int socket_address_listen(
                 const SocketAddress *a,
                 int backlog,
diff --git a/socket.c b/socket.c
index 8e893d4657..91832128f5 100644
--- a/socket.c
+++ b/socket.c
@@ -26,6 +26,7 @@
 #include <fcntl.h>
 #include <sys/epoll.h>
 #include <signal.h>
+#include <arpa/inet.h>
 
 #include "unit.h"
 #include "socket.h"
@@ -33,6 +34,7 @@
 #include "load-dropin.h"
 #include "load-fragment.h"
 #include "strv.h"
+#include "unit-name.h"
 
 static const UnitActiveState state_translation_table[_SOCKET_STATE_MAX] = {
         [SOCKET_DEAD] = UNIT_INACTIVE,
@@ -120,9 +122,40 @@ static void socket_init(Unit *u) {
         s->failure = false;
         s->control_pid = 0;
         s->service = NULL;
+        s->accept = false;
+        s->n_accepted = 0;
         exec_context_init(&s->exec_context);
 }
 
+static bool have_non_accept_socket(Socket *s) {
+        SocketPort *p;
+
+        assert(s);
+
+        if (!s->accept)
+                return true;
+
+        LIST_FOREACH(port, p, s->ports)
+                if (!socket_address_can_accept(&p->address))
+                        return true;
+
+        return false;
+}
+
+static int socket_verify(Socket *s) {
+        assert(s);
+
+        if (UNIT(s)->meta.load_state != UNIT_LOADED)
+                return 0;
+
+        if (!s->ports) {
+                log_error("%s lacks Listen setting. Refusing.", UNIT(s)->meta.id);
+                return -EINVAL;
+        }
+
+        return 0;
+}
+
 static int socket_load(Unit *u) {
         Socket *s = SOCKET(u);
         int r;
@@ -136,11 +169,13 @@ static int socket_load(Unit *u) {
         /* This is a new unit? Then let's add in some extras */
         if (u->meta.load_state == UNIT_LOADED) {
 
-                if ((r = unit_load_related_unit(u, ".service", (Unit**) &s->service)))
-                        return r;
+                if (have_non_accept_socket(s)) {
+                        if ((r = unit_load_related_unit(u, ".service", (Unit**) &s->service)))
+                                return r;
 
-                if ((r = unit_add_dependency(u, UNIT_BEFORE, UNIT(s->service))) < 0)
-                        return r;
+                        if ((r = unit_add_dependency(u, UNIT_BEFORE, UNIT(s->service))) < 0)
+                                return r;
+                }
 
                 if ((r = unit_add_exec_dependencies(u, &s->exec_context)) < 0)
                         return r;
@@ -149,7 +184,7 @@ static int socket_load(Unit *u) {
                         return r;
         }
 
-        return 0;
+        return socket_verify(s);
 }
 
 static const char* listen_lookup(int type) {
@@ -210,6 +245,11 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
                         "%sBindToDevice: %s\n",
                         prefix, s->bind_to_device);
 
+        if (s->accept)
+                fprintf(f,
+                        "%sAccepted: %u\n",
+                        prefix, s->n_accepted);
+
         LIST_FOREACH(port, p, s->ports) {
 
                 if (p->type == SOCKET_SOCKET) {
@@ -243,6 +283,87 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
         free(p2);
 }
 
+static int instance_from_socket(int fd, unsigned nr, char **instance) {
+        socklen_t l;
+        char *r;
+        union {
+                struct sockaddr sa;
+                struct sockaddr_un un;
+                struct sockaddr_in in;
+                struct sockaddr_in6 in6;
+                struct sockaddr_storage storage;
+        } 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 = ntohl(local.in.sin_addr.s_addr),
+                        b = ntohl(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,
+                             ntohs(local.in.sin_port),
+                             b >> 24, (b >> 16) & 0xFF, (b >> 8) & 0xFF, b & 0xFF,
+                             ntohs(remote.in.sin_port)) < 0)
+                        return -ENOMEM;
+
+                break;
+        }
+
+        case AF_INET6: {
+                char a[INET6_ADDRSTRLEN], b[INET6_ADDRSTRLEN];
+
+                if (asprintf(&r,
+                             "%u-%s-%u-%s-%u",
+                             nr,
+                             inet_ntop(AF_INET6, &local.in6.sin6_addr, a, sizeof(a)),
+                             ntohs(local.in6.sin6_port),
+                             inet_ntop(AF_INET6, &remote.in6.sin6_addr, b, sizeof(b)),
+                             ntohs(remote.in6.sin6_port)) < 0)
+                        return -ENOMEM;
+
+                break;
+        }
+
+        case AF_UNIX: {
+                struct ucred ucred;
+
+                l = sizeof(ucred);
+                if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &l) < 0)
+                        return -errno;
+
+                if (asprintf(&r,
+                             "%u-%llu-%llu",
+                             nr,
+                             (unsigned long long) ucred.pid,
+                             (unsigned long long) ucred.uid) < 0)
+                        return -ENOMEM;
+
+                break;
+        }
+
+        default:
+                assert_not_reached("Unhandled socket type.");
+        }
+
+        *instance = r;
+        return 0;
+}
+
 static void socket_close_fds(Socket *s) {
         SocketPort *p;
 
@@ -342,6 +463,10 @@ static int socket_watch_fds(Socket *s) {
                 if (p->fd < 0)
                         continue;
 
+                p->fd_watch.data.socket_accept =
+                        s->accept &&
+                        socket_address_can_accept(&p->address);
+
                 if ((r = unit_watch_fd(UNIT(s), p->fd, EPOLLIN, &p->fd_watch)) < 0)
                         goto fail;
         }
@@ -607,20 +732,59 @@ fail:
         socket_enter_dead(s, false);
 }
 
-static void socket_enter_running(Socket *s) {
+static void socket_enter_running(Socket *s, int cfd) {
         int r;
 
         assert(s);
 
-        if ((r = manager_add_job(UNIT(s)->meta.manager, JOB_START, UNIT(s->service), JOB_REPLACE, true, NULL)) < 0)
-                goto fail;
+        if (cfd < 0) {
+                if ((r = manager_add_job(UNIT(s)->meta.manager, JOB_START, UNIT(s->service), JOB_REPLACE, true, NULL)) < 0)
+                        goto fail;
+
+                socket_set_state(s, SOCKET_RUNNING);
+        } else {
+                Unit *u;
+                char *prefix, *instance, *name;
+
+                if ((r = instance_from_socket(cfd, s->n_accepted++, &instance)))
+                        goto fail;
+
+                if (!(prefix = unit_name_to_prefix(UNIT(s)->meta.id))) {
+                        free(instance);
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                name = unit_name_build(prefix, instance, ".service");
+                free(prefix);
+                free(instance);
+
+                if (!name)
+                        r = -ENOMEM;
+
+                r = manager_load_unit(UNIT(s)->meta.manager, name, NULL, &u);
+                free(name);
+
+                if (r < 0)
+                        goto fail;
+
+                if ((r = service_set_socket_fd(SERVICE(u), cfd) < 0))
+                        goto fail;
+
+                cfd = -1;
+
+                if ((r = manager_add_job(u->meta.manager, JOB_START, u, JOB_REPLACE, true, NULL)) < 0)
+                        goto fail;
+        }
 
-        socket_set_state(s, SOCKET_RUNNING);
         return;
 
 fail:
         log_warning("%s failed to queue socket startup job: %s", s->meta.id, strerror(-r));
         socket_enter_stop_pre(s, false);
+
+        if (cfd >= 0)
+                close_nointr_nofail(cfd);
 }
 
 static void socket_run_next(Socket *s, bool success) {
@@ -673,15 +837,17 @@ static int socket_start(Unit *u) {
                 return 0;
 
         /* Cannot run this without the service being around */
-        if (s->service->meta.load_state != UNIT_LOADED)
-                return -ENOENT;
-
-        /* If the service is alredy actvie we cannot start the
-         * socket */
-        if (s->service->state != SERVICE_DEAD &&
-            s->service->state != SERVICE_MAINTAINANCE &&
-            s->service->state != SERVICE_AUTO_RESTART)
-                return -EBUSY;
+        if (s->service) {
+                if (s->service->meta.load_state != UNIT_LOADED)
+                        return -ENOENT;
+
+                /* If the service is alredy actvie we cannot start the
+                 * socket */
+                if (s->service->state != SERVICE_DEAD &&
+                    s->service->state != SERVICE_MAINTAINANCE &&
+                    s->service->state != SERVICE_AUTO_RESTART)
+                        return -EBUSY;
+        }
 
         assert(s->state == SOCKET_DEAD || s->state == SOCKET_MAINTAINANCE);
 
@@ -730,15 +896,36 @@ static const char *socket_sub_state_to_string(Unit *u) {
 
 static void socket_fd_event(Unit *u, int fd, uint32_t events, Watch *w) {
         Socket *s = SOCKET(u);
+        int cfd = -1;
 
         assert(s);
 
         log_debug("Incoming traffic on %s", u->meta.id);
 
-        if (events != EPOLLIN)
+        if (events != EPOLLIN) {
+                log_error("Got invalid poll event on socket.");
                 socket_enter_stop_pre(s, false);
+                return;
+        }
+
+        if (w->data.socket_accept) {
+                for (;;) {
+
+                        if ((cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK)) < 0) {
+
+                                if (errno == EINTR)
+                                        continue;
+
+                                log_error("Failed to accept socket: %m");
+                                socket_enter_stop_pre(s, false);
+                                return;
+                        }
+
+                        break;
+                }
+        }
 
-        socket_enter_running(s);
+        socket_enter_running(s, cfd);
 }
 
 static void socket_sigchld_event(Unit *u, pid_t pid, int code, int status) {
diff --git a/socket.h b/socket.h
index 6f2a7e811b..5105adfb84 100644
--- a/socket.h
+++ b/socket.h
@@ -102,6 +102,9 @@ struct Socket {
         mode_t directory_mode;
         mode_t socket_mode;
 
+        bool accept;
+        unsigned n_accepted;
+
         bool failure;
         Watch timer_watch;
 };
diff --git a/unit-name.c b/unit-name.c
index 219997b681..eb2f704e2f 100644
--- a/unit-name.c
+++ b/unit-name.c
@@ -29,7 +29,7 @@
         "0123456789"                            \
         "abcdefghijklmnopqrstuvwxyz"            \
         "ABCDEFGHIJKLMNOPQRSTUVWXYZ"            \
-        "-_.\\"
+        ":-_.\\"
 
 UnitType unit_name_to_type(const char *n) {
         UnitType t;
diff --git a/unit.c b/unit.c
index 7f147537e3..872abf3e13 100644
--- a/unit.c
+++ b/unit.c
@@ -1339,13 +1339,22 @@ int unit_add_cgroup(Unit *u, CGroupBonding *b) {
 
 static char *default_cgroup_path(Unit *u) {
         char *p;
+        int r;
 
         assert(u);
 
-        if (asprintf(&p, "%s/%s", u->meta.manager->cgroup_hierarchy, u->meta.id) < 0)
-                return NULL;
+        if (u->meta.instance) {
+                char *t;
 
-        return p;
+                if (!(t = unit_name_template(u->meta.id)))
+                        return NULL;
+
+                r = asprintf(&p, "%s/%s/%s", u->meta.manager->cgroup_hierarchy, t, u->meta.instance);
+                free(t);
+        } else
+                r = asprintf(&p, "%s/%s", u->meta.manager->cgroup_hierarchy, u->meta.id);
+
+        return r < 0 ? NULL : p;
 }
 
 int unit_add_cgroup_from_text(Unit *u, const char *name) {