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-rw-r--r--src/libsystemd-network/lldp-network.c78
1 files changed, 78 insertions, 0 deletions
diff --git a/src/libsystemd-network/lldp-network.c b/src/libsystemd-network/lldp-network.c
new file mode 100644
index 0000000..870584c
--- /dev/null
+++ b/src/libsystemd-network/lldp-network.c
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <linux/filter.h>
+#include <netinet/if_ether.h>
+
+#include "fd-util.h"
+#include "lldp-network.h"
+#include "missing.h"
+#include "socket-util.h"
+
+int lldp_network_bind_raw_socket(int ifindex) {
+
+ static const struct sock_filter filter[] = {
+ BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ethhdr, 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(struct ethhdr, 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(struct ethhdr, 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 */
+ };
+
+ static const struct sock_fprog fprog = {
+ .len = ELEMENTSOF(filter),
+ .filter = (struct sock_filter*) filter,
+ };
+
+ struct packet_mreq mreq = {
+ .mr_ifindex = ifindex,
+ .mr_type = PACKET_MR_MULTICAST,
+ .mr_alen = ETH_ALEN,
+ .mr_address = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x00 }
+ };
+
+ union sockaddr_union saddrll = {
+ .ll.sll_family = AF_PACKET,
+ .ll.sll_ifindex = ifindex,
+ };
+
+ _cleanup_close_ int fd = -1;
+ int r;
+
+ assert(ifindex > 0);
+
+ fd = socket(PF_PACKET, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK,
+ htobe16(ETHERTYPE_LLDP));
+ if (fd < 0)
+ return -errno;
+
+ r = setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
+ if (r < 0)
+ return -errno;
+
+ r = setsockopt(fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
+ if (r < 0)
+ return -errno;
+
+ mreq.mr_address[ETH_ALEN - 1] = 0x03;
+ r = setsockopt(fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
+ if (r < 0)
+ return -errno;
+
+ mreq.mr_address[ETH_ALEN - 1] = 0x0E;
+ r = setsockopt(fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
+ if (r < 0)
+ return -errno;
+
+ r = bind(fd, &saddrll.sa, sizeof(saddrll.ll));
+ if (r < 0)
+ return -errno;
+
+ return TAKE_FD(fd);
+}