networkd: add basic LLDP transmission support

Let's add some minimalistic LLDP sender support. The idea is that this is
either on or off, and all fields determined automatically rather than
configured explicitly.

9 files changed, 439 insertions, 4 deletions

diff --git a/Makefile.am b/Makefile.am
index 70fcedf0da..627a076cd9 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -5341,7 +5341,9 @@ libnetworkd_core_la_SOURCES = \
 	src/network/networkd-address-pool.h \
 	src/network/networkd-address-pool.c \
 	src/network/networkd-util.h \
-	src/network/networkd-util.c
+	src/network/networkd-util.c \
+	src/network/networkd-lldp-tx.h \
+	src/network/networkd-lldp-tx.c
 
 nodist_libnetworkd_core_la_SOURCES = \
 	src/network/networkd-network-gperf.c \
diff --git a/src/basic/hostname-util.c b/src/basic/hostname-util.c
index 57031b645c..f900c509a3 100644
--- a/src/basic/hostname-util.c
+++ b/src/basic/hostname-util.c
@@ -48,6 +48,9 @@ bool hostname_is_set(void) {
 char* gethostname_malloc(void) {
         struct utsname u;
 
+        /* This call tries to return something useful, either the actual hostname or it makes something up. The only
+         * reason it might mail is OOM. It might even return "localhost" if that's set. */
+
         assert_se(uname(&u) >= 0);
 
         if (isempty(u.nodename) || streq(u.nodename, "(none)"))
@@ -56,6 +59,31 @@ char* gethostname_malloc(void) {
         return strdup(u.nodename);
 }
 
+int gethostname_strict(char **ret) {
+        struct utsname u;
+        char *k;
+
+        /* This call will rather fail than make up a name. It will not return "localhost" either. */
+
+        assert_se(uname(&u) >= 0);
+
+        if (isempty(u.nodename))
+                return -ENXIO;
+
+        if (streq(u.nodename, "(none)"))
+                return -ENXIO;
+
+        if (is_localhost(u.nodename))
+                return -ENXIO;
+
+        k = strdup(u.nodename);
+        if (!k)
+                return -ENOMEM;
+
+        *ret = k;
+        return 0;
+}
+
 static bool hostname_valid_char(char c) {
         return
                 (c >= 'a' && c <= 'z') ||
diff --git a/src/basic/hostname-util.h b/src/basic/hostname-util.h
index d062eddea1..7af4e6c7ec 100644
--- a/src/basic/hostname-util.h
+++ b/src/basic/hostname-util.h
@@ -26,6 +26,7 @@
 bool hostname_is_set(void);
 
 char* gethostname_malloc(void);
+int gethostname_strict(char **ret);
 
 bool hostname_is_valid(const char *s, bool allow_trailing_dot) _pure_;
 char* hostname_cleanup(char *s);
diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index 2bc6e3c842..86fa4f07f2 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -30,6 +30,7 @@
 #include "netlink-util.h"
 #include "network-internal.h"
 #include "networkd-link.h"
+#include "networkd-lldp-tx.h"
 #include "networkd-netdev.h"
 #include "set.h"
 #include "socket-util.h"
@@ -99,7 +100,7 @@ static bool link_ipv6ll_enabled(Link *link) {
         return link->network->link_local & ADDRESS_FAMILY_IPV6;
 }
 
-static bool link_lldp_enabled(Link *link) {
+static bool link_lldp_rx_enabled(Link *link) {
         assert(link);
 
         if (link->flags & IFF_LOOPBACK)
@@ -117,6 +118,21 @@ static bool link_lldp_enabled(Link *link) {
         return link->network->lldp_mode != LLDP_MODE_NO;
 }
 
+static bool link_lldp_tx_enabled(Link *link) {
+        assert(link);
+
+        if (link->flags & IFF_LOOPBACK)
+                return false;
+
+        if (link->iftype != ARPHRD_ETHER)
+                return false;
+
+        if (!link->network)
+                return false;
+
+        return link->network->lldp_emit;
+}
+
 static bool link_ipv4_forward_enabled(Link *link) {
         assert(link);
 
@@ -419,6 +435,8 @@ static void link_free(Link *link) {
         sd_dhcp_client_unref(link->dhcp_client);
         sd_dhcp_lease_unref(link->dhcp_lease);
 
+        link_lldp_tx_stop(link);
+
         free(link->lease_file);
 
         sd_lldp_unref(link->lldp);
@@ -546,6 +564,7 @@ static int link_stop_clients(Link *link) {
                         r = log_link_warning_errno(link, k, "Could not stop IPv6 Router Discovery: %m");
         }
 
+        link_lldp_tx_stop(link);
         return r;
 }
 
@@ -1383,6 +1402,12 @@ static int link_acquire_conf(Link *link) {
                         return log_link_warning_errno(link, r, "Could not acquire DHCPv4 lease: %m");
         }
 
+        if (link_lldp_tx_enabled(link)) {
+                r = link_lldp_tx_start(link);
+                if (r < 0)
+                        return log_link_warning_errno(link, r, "Failed to start LLDP transmission: %m");
+        }
+
         return 0;
 }
 
@@ -2191,7 +2216,7 @@ static int link_configure(Link *link) {
                         return r;
         }
 
-        if (link_lldp_enabled(link)) {
+        if (link_lldp_rx_enabled(link)) {
                 r = sd_lldp_new(&link->lldp, link->ifindex);
                 if (r < 0)
                         return r;
diff --git a/src/network/networkd-link.h b/src/network/networkd-link.h
index d9f637cb6e..f2a64ca9b5 100644
--- a/src/network/networkd-link.h
+++ b/src/network/networkd-link.h
@@ -112,9 +112,14 @@ struct Link {
         sd_dhcp6_client *dhcp6_client;
         bool rtnl_extended_attrs;
 
+        /* This is about LLDP reception */
         sd_lldp *lldp;
         char *lldp_file;
 
+        /* This is about LLDP transmission */
+        unsigned lldp_tx_fast; /* The LLDP txFast counter (See 802.1ab-2009, section 9.2.5.18) */
+        sd_event_source *lldp_tx_event_source;
+
         Hashmap *bound_by_links;
         Hashmap *bound_to_links;
 };
diff --git a/src/network/networkd-lldp-tx.c b/src/network/networkd-lldp-tx.c
new file mode 100644
index 0000000000..ae8367a60e
--- /dev/null
+++ b/src/network/networkd-lldp-tx.c
@@ -0,0 +1,347 @@
+/***
+  This file is part of systemd.
+
+  Copyright 2016 Lennart Poettering
+
+  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 <endian.h>
+#include <inttypes.h>
+#include <string.h>
+
+#include "fd-util.h"
+#include "fileio.h"
+#include "hostname-util.h"
+#include "lldp.h"
+#include "networkd-lldp-tx.h"
+#include "random-util.h"
+#include "socket-util.h"
+#include "string-util.h"
+#include "unaligned.h"
+
+/* The LLDP spec calls this "txFastInit", see 9.2.5.19 */
+#define LLDP_TX_FAST_INIT 4U
+
+/* The LLDP spec calls this "msgTxHold", see 9.2.5.6 */
+#define LLDP_TX_HOLD 4U
+
+/* The jitter range to add, see 9.2.2. */
+#define LLDP_JITTER_USEC (400U * USEC_PER_MSEC)
+
+/* The LLDP spec calls this msgTxInterval, but we subtract half the jitter off it. */
+#define LLDP_TX_INTERVAL_USEC (30U * USEC_PER_SEC - LLDP_JITTER_USEC / 2)
+
+/* The LLDP spec calls this msgFastTx, but we subtract half the jitter off it. */
+#define LLDP_FAST_TX_USEC (1U * USEC_PER_SEC - LLDP_JITTER_USEC / 2)
+
+static int lldp_write_tlv_header(uint8_t **p, uint8_t id, size_t sz) {
+        assert(p);
+
+        if (id > 127)
+                return -EBADMSG;
+        if (sz > 511)
+                return -ENOBUFS;
+
+        (*p)[0] = (id << 1) | !!(sz & 256);
+        (*p)[1] = sz & 255;
+
+        *p = *p + 2;
+        return 0;
+}
+
+static int lldp_make_packet(
+                const struct ether_addr *hwaddr,
+                const char *machine_id,
+                const char *ifname,
+                uint16_t ttl,
+                const char *port_description,
+                const char *hostname,
+                const char *pretty_hostname,
+                uint16_t system_capabilities,
+                uint16_t enabled_capabilities,
+                void **ret, size_t *sz) {
+
+        size_t machine_id_length, ifname_length, port_description_length = 0, hostname_length = 0, pretty_hostname_length = 0;
+        _cleanup_free_ void *packet = NULL;
+        struct ether_header *h;
+        uint8_t *p;
+        size_t l;
+        int r;
+
+        assert(hwaddr);
+        assert(machine_id);
+        assert(ifname);
+        assert(ret);
+        assert(sz);
+
+        machine_id_length = strlen(machine_id);
+        ifname_length = strlen(ifname);
+
+        if (port_description)
+                port_description_length = strlen(port_description);
+
+        if (hostname)
+                hostname_length = strlen(hostname);
+
+        if (pretty_hostname)
+                pretty_hostname_length = strlen(pretty_hostname);
+
+        l = sizeof(struct ether_header) +
+                /* Chassis ID */
+                2 + 1 + machine_id_length +
+                /* Port ID */
+                2 + 1 + ifname_length +
+                /* TTL */
+                2 + 2 +
+                /* System Capabilities */
+                2 + 4 +
+                /* End */
+                2;
+
+        /* Port Description */
+        if (port_description)
+                l += 2 + port_description_length;
+
+        /* System Name */
+        if (hostname)
+                l += 2 + hostname_length;
+
+        /* System Description */
+        if (pretty_hostname)
+                l += 2 + pretty_hostname_length;
+
+        packet = malloc(l);
+        if (!packet)
+                return -ENOMEM;
+
+        h = (struct ether_header*) packet;
+        h->ether_type = htobe16(ETHERTYPE_LLDP);
+        memcpy(h->ether_dhost, &(struct ether_addr) { LLDP_MULTICAST_ADDR }, ETH_ALEN);
+        memcpy(h->ether_shost, hwaddr, ETH_ALEN);
+
+        p = (uint8_t*) packet + sizeof(struct ether_header);
+
+        r = lldp_write_tlv_header(&p, LLDP_TYPE_CHASSIS_ID, 1 + machine_id_length);
+        if (r < 0)
+                return r;
+        *(p++) = LLDP_CHASSIS_SUBTYPE_LOCALLY_ASSIGNED;
+        p = mempcpy(p, machine_id, machine_id_length);
+
+        r = lldp_write_tlv_header(&p, LLDP_TYPE_PORT_ID, 1 + ifname_length);
+        if (r < 0)
+                return r;
+        *(p++) = LLDP_PORT_SUBTYPE_INTERFACE_NAME;
+        p = mempcpy(p, ifname, ifname_length);
+
+        r = lldp_write_tlv_header(&p, LLDP_TYPE_TTL, 2);
+        if (r < 0)
+                return r;
+        unaligned_write_be16(p, ttl);
+        p += 2;
+
+        if (port_description) {
+                r = lldp_write_tlv_header(&p, LLDP_TYPE_PORT_DESCRIPTION, port_description_length);
+                if (r < 0)
+                        return r;
+                p = mempcpy(p, port_description, port_description_length);
+        }
+
+        if (hostname) {
+                r = lldp_write_tlv_header(&p, LLDP_TYPE_SYSTEM_NAME, hostname_length);
+                if (r < 0)
+                        return r;
+                p = mempcpy(p, hostname, hostname_length);
+        }
+
+        if (pretty_hostname) {
+                r = lldp_write_tlv_header(&p, LLDP_TYPE_SYSTEM_DESCRIPTION, pretty_hostname_length);
+                if (r < 0)
+                        return r;
+                p = mempcpy(p, pretty_hostname, pretty_hostname_length);
+        }
+
+        r = lldp_write_tlv_header(&p, LLDP_TYPE_SYSTEM_CAPABILITIES, 4);
+        if (r < 0)
+                return r;
+        unaligned_write_be16(p, system_capabilities);
+        p += 2;
+        unaligned_write_be16(p, enabled_capabilities);
+        p += 2;
+
+        r = lldp_write_tlv_header(&p, LLDP_TYPE_END, 0);
+        if (r < 0)
+                return r;
+
+        assert(p == (uint8_t*) packet + l);
+
+        *ret = packet;
+        *sz = l;
+
+        packet = NULL;
+        return 0;
+}
+
+static int lldp_send_packet(int ifindex, const void *packet, size_t packet_size) {
+
+        union sockaddr_union sa = {
+                .ll.sll_family = AF_PACKET,
+                .ll.sll_protocol = htobe16(ETHERTYPE_LLDP),
+                .ll.sll_ifindex = ifindex,
+                .ll.sll_halen = ETH_ALEN,
+                .ll.sll_addr = LLDP_MULTICAST_ADDR,
+        };
+
+        _cleanup_close_ int fd = -1;
+        ssize_t l;
+
+        assert(ifindex > 0);
+        assert(packet || packet_size <= 0);
+
+        fd = socket(PF_PACKET, SOCK_RAW|SOCK_CLOEXEC, IPPROTO_RAW);
+        if (fd < 0)
+                return -errno;
+
+        l = sendto(fd, packet, packet_size, MSG_NOSIGNAL, &sa.sa, sizeof(sa.ll));
+        if (l < 0)
+                return -errno;
+
+        if ((size_t) l != packet_size)
+                return -EIO;
+
+        return 0;
+}
+
+static int link_send_lldp(Link *link) {
+        char machine_id_string[SD_ID128_STRING_MAX];
+        _cleanup_free_ char *hostname = NULL, *pretty_hostname = NULL;
+        _cleanup_free_ void *packet = NULL;
+        size_t packet_size = 0;
+        sd_id128_t machine_id;
+        uint16_t caps;
+        usec_t ttl;
+        int r;
+
+        r = sd_id128_get_machine(&machine_id);
+        if (r < 0)
+                return r;
+
+        (void) gethostname_strict(&hostname);
+        (void) parse_env_file("/etc/machine-info", NEWLINE, "PRETTY_HOSTNAME", &pretty_hostname, NULL);
+
+        ttl = DIV_ROUND_UP(LLDP_TX_INTERVAL_USEC * LLDP_TX_HOLD + 1, USEC_PER_SEC);
+        if (ttl > (usec_t) UINT16_MAX)
+                ttl = (usec_t) UINT16_MAX;
+
+        caps = (link->network && link->network->ip_forward != ADDRESS_FAMILY_NO) ?
+                LLDP_SYSTEM_CAPABILITIES_ROUTER :
+                LLDP_SYSTEM_CAPABILITIES_STATION;
+
+        r = lldp_make_packet(&link->mac,
+                             sd_id128_to_string(machine_id, machine_id_string),
+                             link->ifname,
+                             (uint16_t) ttl,
+                             link->network ? link->network->description : NULL,
+                             hostname,
+                             pretty_hostname,
+                             LLDP_SYSTEM_CAPABILITIES_STATION|LLDP_SYSTEM_CAPABILITIES_BRIDGE|LLDP_SYSTEM_CAPABILITIES_ROUTER,
+                             caps,
+                             &packet, &packet_size);
+        if (r < 0)
+                return r;
+
+        return lldp_send_packet(link->ifindex, packet, packet_size);
+}
+
+static int on_lldp_timer(sd_event_source *s, usec_t t, void *userdata) {
+        Link *link = userdata;
+        usec_t current, delay, next;
+        int r;
+
+        assert(s);
+        assert(userdata);
+
+        log_link_debug(link, "Sending LLDP packet...");
+
+        r = link_send_lldp(link);
+        if (r < 0)
+                log_link_debug_errno(link, r, "Failed to send LLDP packet, ignoring: %m");
+
+        if (link->lldp_tx_fast > 0)
+                link->lldp_tx_fast--;
+
+        assert_se(sd_event_now(sd_event_source_get_event(s), clock_boottime_or_monotonic(), &current) >= 0);
+
+        delay = link->lldp_tx_fast > 0 ? LLDP_FAST_TX_USEC : LLDP_TX_INTERVAL_USEC;
+        next = usec_add(usec_add(current, delay), (usec_t) random_u64() % LLDP_JITTER_USEC);
+
+        r = sd_event_source_set_time(s, next);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Failed to restart LLDP timer: %m");
+
+        r = sd_event_source_set_enabled(s, SD_EVENT_ONESHOT);
+        if (r < 0)
+                return log_link_error_errno(link, r, "Failed to enable LLDP timer: %m");
+
+        return 0;
+}
+
+int link_lldp_tx_start(Link *link) {
+        usec_t next;
+        int r;
+
+        assert(link);
+
+        /* Starts the LLDP transmission in "fast" mode. If it is already started, turns "fast" mode back on again. */
+
+        link->lldp_tx_fast = LLDP_TX_FAST_INIT;
+
+        next = usec_add(usec_add(now(clock_boottime_or_monotonic()), LLDP_FAST_TX_USEC),
+                     (usec_t) random_u64() % LLDP_JITTER_USEC);
+
+        if (link->lldp_tx_event_source) {
+                usec_t old;
+
+                /* Lower the timeout, maybe */
+                r = sd_event_source_get_time(link->lldp_tx_event_source, &old);
+                if (r < 0)
+                        return r;
+
+                if (old <= next)
+                        return 0;
+
+                return sd_event_source_set_time(link->lldp_tx_event_source, next);
+        } else {
+                r = sd_event_add_time(
+                                link->manager->event,
+                                &link->lldp_tx_event_source,
+                                clock_boottime_or_monotonic(),
+                                next,
+                                0,
+                                on_lldp_timer,
+                                link);
+                if (r < 0)
+                        return r;
+
+                (void) sd_event_source_set_description(link->lldp_tx_event_source, "lldp-tx");
+        }
+
+        return 0;
+}
+
+void link_lldp_tx_stop(Link *link) {
+        assert(link);
+
+        link->lldp_tx_event_source = sd_event_source_unref(link->lldp_tx_event_source);
+}
diff --git a/src/network/networkd-lldp-tx.h b/src/network/networkd-lldp-tx.h
new file mode 100644
index 0000000000..8c7f403005
--- /dev/null
+++ b/src/network/networkd-lldp-tx.h
@@ -0,0 +1,25 @@
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2016 Lennart Poettering
+
+  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 "networkd-link.h"
+
+int link_lldp_tx_start(Link *link);
+void link_lldp_tx_stop(Link *link);
diff --git a/src/network/networkd-network-gperf.gperf b/src/network/networkd-network-gperf.gperf
index d67da5d7b6..a5d1714293 100644
--- a/src/network/networkd-network-gperf.gperf
+++ b/src/network/networkd-network-gperf.gperf
@@ -41,6 +41,7 @@ Network.LinkLocalAddressing,            config_parse_address_family_boolean,
 Network.IPv4LLRoute,                    config_parse_bool,                              0,                             offsetof(Network, ipv4ll_route)
 Network.IPv6Token,                      config_parse_ipv6token,                         0,                             offsetof(Network, ipv6_token)
 Network.LLDP,                           config_parse_lldp_mode,                         0,                             offsetof(Network, lldp_mode)
+Network.EmitLLDP,                       config_parse_bool,                              0,                             offsetof(Network, lldp_emit)
 Network.Address,                        config_parse_address,                           0,                             0
 Network.Gateway,                        config_parse_gateway,                           0,                             0
 Network.Domains,                        config_parse_domains,                           0,                             0
diff --git a/src/network/networkd-network.h b/src/network/networkd-network.h
index 9dcebfbf7b..4a13e2b574 100644
--- a/src/network/networkd-network.h
+++ b/src/network/networkd-network.h
@@ -145,7 +145,8 @@ struct Network {
         struct ether_addr *mac;
         unsigned mtu;
 
-        LLDPMode lldp_mode;
+        LLDPMode lldp_mode; /* LLDP reception */
+        bool lldp_emit;     /* LLDP transmission */
 
         LIST_HEAD(Address, static_addresses);
         LIST_HEAD(Route, static_routes);