sd-network: IPv4 link-local support [v2]

Implements IPv4LL with respect to RFC 3927
(http://tools.ietf.org/rfc/rfc3927.txt) and integrates it
with networkd. Majority of the IPv4LL state machine is
taken from avahi (http://avahi.org/) project's autoip.

IPv4LL can be enabled by IPv4LL=yes under [Network]
section of .network file.

IPv4LL works independent of DHCP but if DHCP lease is
aquired, then LL address will be dropped.

[tomegun: removed a trailing newline and a compiler warning]

1 files changed, 56 insertions, 0 deletions

diff --git a/src/libsystemd-network/ipv4ll-network.c b/src/libsystemd-network/ipv4ll-network.c
new file mode 100644
index 0000000000..51734d7e4d
--- /dev/null
+++ b/src/libsystemd-network/ipv4ll-network.c
@@ -0,0 +1,56 @@
+/***
+  This file is part of systemd.
+
+  Copyright (C) 2014 Axis Communications AB. All rights reserved.
+
+  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 "util.h"
+#include "ipv4ll-internal.h"
+
+int arp_network_send_raw_socket(int fd, const union sockaddr_union *link,
+                                        const struct ether_arp *arp) {
+        assert(arp);
+        assert(link);
+        assert(fd >= 0);
+
+        if (sendto(fd, arp, sizeof(struct ether_arp), 0, &link->sa, sizeof(link->ll)) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int arp_network_bind_raw_socket(int index, union sockaddr_union *link) {
+        int s;
+
+        assert(index > 0);
+        assert(link);
+
+        s = socket(PF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, htons(ETH_P_ARP));
+        if (s < 0)
+                return -errno;
+
+        link->ll.sll_family = AF_PACKET;
+        link->ll.sll_ifindex = index;
+        link->ll.sll_protocol = htons(ETH_P_ARP);
+        link->ll.sll_halen = ETH_ALEN;
+
+        if (bind(s, &link->sa, sizeof(link->ll)) < 0) {
+                close_nointr_nofail(s);
+                return -errno;
+        }
+
+        return s;
+}