sd-dhcp-server: add basic functionality for starting/stopping server

Bind to UDP socket and listen for messages, discarding anything we receive.

3 files changed, 97 insertions, 0 deletions

diff --git a/src/libsystemd-network/dhcp-server-internal.h b/src/libsystemd-network/dhcp-server-internal.h
index e09b35936f..8191ef7fd7 100644
--- a/src/libsystemd-network/dhcp-server-internal.h
+++ b/src/libsystemd-network/dhcp-server-internal.h
@@ -32,6 +32,8 @@ struct sd_dhcp_server {
 
         sd_event *event;
         int event_priority;
+        sd_event_source *receive_message;
+        int fd;
 };
 
 DEFINE_TRIVIAL_CLEANUP_FUNC(sd_dhcp_server*, sd_dhcp_server_unref);
diff --git a/src/libsystemd-network/sd-dhcp-server.c b/src/libsystemd-network/sd-dhcp-server.c
index 885d68d335..a9768f8fa2 100644
--- a/src/libsystemd-network/sd-dhcp-server.c
+++ b/src/libsystemd-network/sd-dhcp-server.c
@@ -20,8 +20,11 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+#include <sys/ioctl.h>
+
 #include "sd-dhcp-server.h"
 #include "dhcp-server-internal.h"
+#include "dhcp-internal.h"
 
 sd_dhcp_server *sd_dhcp_server_ref(sd_dhcp_server *server) {
         if (server)
@@ -34,6 +37,8 @@ sd_dhcp_server *sd_dhcp_server_unref(sd_dhcp_server *server) {
         if (server && REFCNT_DEC(server->n_ref) <= 0) {
                 log_dhcp_server(server, "UNREF");
 
+                sd_dhcp_server_stop(server);
+
                 sd_event_unref(server->event);
                 free(server);
         }
@@ -51,6 +56,7 @@ int sd_dhcp_server_new(sd_dhcp_server **ret) {
                 return -ENOMEM;
 
         server->n_ref = REFCNT_INIT;
+        server->fd = -1;
 
         *ret = server;
         server = NULL;
@@ -90,3 +96,86 @@ sd_event *sd_dhcp_server_get_event(sd_dhcp_server *server) {
 
         return server->event;
 }
+
+int sd_dhcp_server_stop(sd_dhcp_server *server) {
+        assert_return(server, -EINVAL);
+
+        server->receive_message =
+                sd_event_source_unref(server->receive_message);
+
+        server->fd = safe_close(server->fd);
+
+        log_dhcp_server(server, "STOPPED");
+
+        return 0;
+}
+
+static int server_receive_message(sd_event_source *s, int fd,
+                                  uint32_t revents, void *userdata) {
+        _cleanup_free_ uint8_t *message = NULL;
+        sd_dhcp_server *server = userdata;
+        struct iovec iov = {};
+        struct msghdr msg = {
+                .msg_iov = &iov,
+                .msg_iovlen = 1,
+        };
+        int buflen = 0, len, r;
+
+        assert(server);
+
+        r = ioctl(fd, FIONREAD, &buflen);
+        if (r < 0)
+                return r;
+        if (buflen < 0)
+                return -EIO;
+
+        message = malloc0(buflen);
+        if (!message)
+                return -ENOMEM;
+
+        iov.iov_base = message;
+        iov.iov_len = buflen;
+
+        len = recvmsg(fd, &msg, 0);
+        if (len < buflen)
+                return 0;
+
+        log_dhcp_server(server, "received message");
+
+        return 1;
+}
+
+int sd_dhcp_server_start(sd_dhcp_server *server) {
+        int r;
+
+        assert_return(server, -EINVAL);
+        assert_return(server->event, -EINVAL);
+        assert_return(!server->receive_message, -EBUSY);
+        assert_return(server->fd == -1, -EBUSY);
+
+        r = dhcp_network_bind_udp_socket(INADDR_ANY, DHCP_PORT_SERVER);
+        if (r < 0) {
+                sd_dhcp_server_stop(server);
+                return r;
+        }
+        server->fd = r;
+
+        r = sd_event_add_io(server->event, &server->receive_message,
+                            server->fd, EPOLLIN,
+                            server_receive_message, server);
+        if (r < 0) {
+                sd_dhcp_server_stop(server);
+                return r;
+        }
+
+        r = sd_event_source_set_priority(server->receive_message,
+                                         server->event_priority);
+        if (r < 0) {
+                sd_dhcp_server_stop(server);
+                return r;
+        }
+
+        log_dhcp_server(server, "STARTED");
+
+        return 0;
+}
diff --git a/src/libsystemd-network/test-dhcp-server.c b/src/libsystemd-network/test-dhcp-server.c
index bd0913d51c..80d2184b70 100644
--- a/src/libsystemd-network/test-dhcp-server.c
+++ b/src/libsystemd-network/test-dhcp-server.c
@@ -45,6 +45,12 @@ static void test_basic(sd_event *event) {
 
         assert_se(sd_dhcp_server_ref(server) == server);
         assert_se(!sd_dhcp_server_unref(server));
+
+        assert_se(sd_dhcp_server_start(server) >= 0);
+        assert_se(sd_dhcp_server_start(server) == -EBUSY);
+        assert_se(sd_dhcp_server_stop(server) >= 0);
+        assert_se(sd_dhcp_server_stop(server) >= 0);
+        assert_se(sd_dhcp_server_start(server) >= 0);
 }
 
 int main(int argc, char *argv[]) {