libsystemd-rtnl: add a rtnetlink library

This is intentionally as similar to sd-bus as possible. While it
would be simple to export it, the intentions is to keep this
internal (at least for the forseeable future).

Currently only synchronous communication is implemented

1 files changed, 188 insertions, 0 deletions

diff --git a/src/libsystemd-rtnl/sd-rtnl.c b/src/libsystemd-rtnl/sd-rtnl.c
new file mode 100644
index 0000000000..abf45d0eed
--- /dev/null
+++ b/src/libsystemd-rtnl/sd-rtnl.c
@@ -0,0 +1,188 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 Tom Gundersen <teg@jklm.no>
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <sys/socket.h>
+#include <poll.h>
+
+#include "macro.h"
+#include "util.h"
+
+#include "sd-rtnl.h"
+#include "rtnl-internal.h"
+
+static int sd_rtnl_new(sd_rtnl **ret) {
+        sd_rtnl *rtnl;
+
+        assert_return(ret, -EINVAL);
+
+        rtnl = new0(sd_rtnl, 1);
+        if (!rtnl)
+                return -ENOMEM;
+
+        rtnl->n_ref = REFCNT_INIT;
+
+        rtnl->fd = -1;
+
+        rtnl->sockaddr.nl.nl_family = AF_NETLINK;
+
+        *ret = rtnl;
+        return 0;
+}
+
+int sd_rtnl_open(__u32 groups, sd_rtnl **ret) {
+        sd_rtnl *rtnl;
+        int r;
+
+        r = sd_rtnl_new(&rtnl);
+        if (r < 0)
+                return r;
+
+        rtnl->fd = socket(PF_NETLINK, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, NETLINK_ROUTE);
+        if (rtnl->fd < 0) {
+                r = -errno;
+                sd_rtnl_unref(rtnl);
+                return r;
+        }
+
+        rtnl->sockaddr.nl.nl_groups = groups;
+
+        r = bind(rtnl->fd, &rtnl->sockaddr.sa, sizeof(rtnl->sockaddr));
+        if (r < 0) {
+                r = -errno;
+                sd_rtnl_unref(rtnl);
+                return r;
+        }
+
+        *ret = rtnl;
+
+        return 0;
+}
+
+sd_rtnl *sd_rtnl_ref(sd_rtnl *rtnl) {
+        if (rtnl)
+                assert_se(REFCNT_INC(rtnl->n_ref) >= 2);
+
+        return rtnl;
+}
+
+sd_rtnl *sd_rtnl_unref(sd_rtnl *rtnl) {
+        if (rtnl && REFCNT_DEC(rtnl->n_ref) <= 0) {
+                if (rtnl->fd >= 0)
+                        close_nointr_nofail(rtnl->fd);
+                free(rtnl);
+        }
+
+        return NULL;
+}
+
+int sd_rtnl_send_with_reply_and_block(sd_rtnl *nl,
+                                        sd_rtnl_message *message,
+                                        uint64_t usec,
+                                        sd_rtnl_message **ret) {
+        struct pollfd p[1] = {};
+        sd_rtnl_message *reply;
+        struct timespec left;
+        usec_t timeout;
+        int r, serial;
+
+        assert_return(nl, -EINVAL);
+        assert_return(message, -EINVAL);
+
+        r = message_seal(nl, message);
+        if (r < 0)
+                return r;
+
+        serial = message_get_serial(message);
+
+        p[0].fd = nl->fd;
+        p[0].events = POLLOUT;
+
+        timeout = now(CLOCK_MONOTONIC) + usec;
+
+        for (;;) {
+                if (usec != (uint64_t) -1) {
+                        usec_t n;
+
+                        n = now(CLOCK_MONOTONIC);
+                        if (n >= timeout)
+                                return -ETIMEDOUT;
+
+                        timespec_store(&left, timeout - n);
+                }
+
+                r = ppoll(p, 1, usec == (uint64_t) -1 ? NULL : &left, NULL);
+                if (r < 0)
+                        return 0;
+
+                r = socket_write_message(nl, message);
+                if (r < 0)
+                        return r;
+
+                if (r > 0) {
+                        break;
+                }
+        }
+
+        p[0].events = POLLIN;
+
+        for (;;) {
+                if (usec != (uint64_t) -1) {
+                        usec_t n;
+
+                        n = now(CLOCK_MONOTONIC);
+                        if (n >= timeout)
+                                return -ETIMEDOUT;
+
+                        timespec_store(&left, timeout - n);
+                }
+
+                r = ppoll(p, 1, usec == (uint64_t) -1 ? NULL : &left, NULL);
+                if (r < 0)
+                        return r;
+
+                r = socket_read_message(nl, &reply);
+                if (r < 0)
+                        return r;
+
+                if (r > 0) {
+                        int received_serial = message_get_serial(reply);
+
+                        if (received_serial == serial) {
+                                r = message_get_errno(reply);
+                                if (r < 0) {
+                                        sd_rtnl_message_unref(reply);
+                                        return r;
+                                }
+
+                                if (ret)
+                                        *ret = reply;
+                                else
+                                        reply = sd_rtnl_message_unref(reply);
+
+                                break;;
+                        }
+
+                        reply = sd_rtnl_message_unref(reply);
+                }
+        }
+
+        return 0;
+}