networkd: Introduce Link Layer Discovery Protocol (LLDP)

This patch introduces LLDP support to networkd. it implements the
receiver side of the protocol.

The Link Layer Discovery Protocol (LLDP) is an industry-standard,
vendor-neutral method to allow networked devices to advertise
capabilities, identity, and other information onto a LAN. The Layer 2
protocol, detailed in IEEE 802.1AB-2005.LLDP allows network devices
that operate at the lower layers of a protocol stack (such as
Layer 2 bridges and switches) to learn some of the capabilities
and characteristics of LAN devices available to higher
layer protocols.

1 files changed, 111 insertions, 0 deletions

diff --git a/src/libsystemd-network/lldp-network.c b/src/libsystemd-network/lldp-network.c
new file mode 100644
index 0000000000..cfab91146c
--- /dev/null
+++ b/src/libsystemd-network/lldp-network.c
@@ -0,0 +1,111 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright (C) 2014 Tom Gundersen
+  Copyright (C) 2014 Susant Sahani
+
+  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 <linux/filter.h>
+#include <linux/if_ether.h>
+
+#include "socket-util.h"
+#include "lldp-tlv.h"
+#include "lldp-network.h"
+#include "sd-lldp.h"
+
+int lldp_network_bind_raw_socket(int ifindex) {
+        typedef struct LLDPFrame {
+                struct ethhdr hdr;
+                uint8_t tlvs[0];
+        } LLDPFrame;
+
+        struct sock_filter filter[] = {
+                BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(LLDPFrame, hdr.h_dest)),      /* A <- 4 bytes of destination MAC */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0180c200, 1, 0),                    /* A != 01:80:c2:00 */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                             /* drop packet */
+                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(LLDPFrame, hdr.h_dest) + 4),  /* A <- remaining 2 bytes of destination MAC */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0000, 3, 0),                        /* A != 00:00 */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0003, 2, 0),                        /* A != 00:03 */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x000e, 1, 0),                        /* A != 00:0e */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                             /* drop packet */
+                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(LLDPFrame, hdr.h_proto)),     /* A <- protocol */
+                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_LLDP, 1, 0),                /* A != ETHERTYPE_LLDP */
+                BPF_STMT(BPF_RET + BPF_K, 0),                                             /* drop packet */
+                BPF_STMT(BPF_RET + BPF_K, (uint32_t) -1),                                 /* accept packet */
+        };
+
+        struct sock_fprog fprog = {
+                .len = ELEMENTSOF(filter),
+                .filter = filter
+        };
+
+        _cleanup_close_ int s = -1;
+
+        union sockaddr_union saddrll = {
+                .ll.sll_family = AF_PACKET,
+                .ll.sll_ifindex = ifindex,
+        };
+
+        int r;
+
+        assert(ifindex > 0);
+
+        s = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
+        if (s < 0)
+                return -errno;
+
+        r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
+        if (r < 0)
+                return -errno;
+
+        r = bind(s, &saddrll.sa, sizeof(saddrll.ll));
+        if (r < 0)
+                return -errno;
+
+        r = s;
+        s = -1;
+
+        return r;
+}
+
+int lldp_receive_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        _cleanup_tlv_packet_free_ tlv_packet *packet = NULL;
+        tlv_packet *p;
+        uint16_t length;
+        int r;
+
+        assert(fd);
+        assert(userdata);
+
+        r = tlv_packet_new(&packet);
+        if (r < 0)
+                return r;
+
+        length = read(fd, &packet->pdu, sizeof(packet->pdu));
+
+        /* Silently drop the packet */
+        if ((size_t) length > ETHER_MAX_LEN)
+                return 0;
+
+        packet->userdata = userdata;
+
+        p = packet;
+        packet = NULL;
+
+        return lldp_handle_packet(p, (uint16_t) length);
+}