diff options
Diffstat (limited to 'src/libsystemd-network/sd-ipv4ll.c')
| -rw-r--r-- | src/libsystemd-network/sd-ipv4ll.c | 519 |
1 files changed, 519 insertions, 0 deletions
diff --git a/src/libsystemd-network/sd-ipv4ll.c b/src/libsystemd-network/sd-ipv4ll.c new file mode 100644 index 0000000000..c6f6e01431 --- /dev/null +++ b/src/libsystemd-network/sd-ipv4ll.c @@ -0,0 +1,519 @@ +/*** + 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 <stdlib.h> +#include <errno.h> +#include <string.h> +#include <stdio.h> +#include <arpa/inet.h> + +#include "util.h" +#include "list.h" + +#include "ipv4ll-internal.h" +#include "sd-ipv4ll.h" + +/* Constants from the RFC */ +#define PROBE_WAIT 1 +#define PROBE_NUM 3 +#define PROBE_MIN 1 +#define PROBE_MAX 2 +#define ANNOUNCE_WAIT 2 +#define ANNOUNCE_NUM 2 +#define ANNOUNCE_INTERVAL 2 +#define MAX_CONFLICTS 10 +#define RATE_LIMIT_INTERVAL 60 +#define DEFEND_INTERVAL 10 + +#define IPV4LL_NETWORK 0xA9FE0000L +#define IPV4LL_NETMASK 0xFFFF0000L + +typedef enum IPv4LLTrigger{ + IPV4LL_TRIGGER_NULL, + IPV4LL_TRIGGER_PACKET, + IPV4LL_TRIGGER_TIMEOUT, + _IPV4LL_TRIGGER_MAX, + _IPV4LL_TRIGGER_INVALID = -1 +} IPv4LLTrigger; + +typedef enum IPv4LLState { + IPV4LL_STATE_INIT, + IPV4LL_STATE_WAITING_PROBE, + IPV4LL_STATE_PROBING, + IPV4LL_STATE_WAITING_ANNOUNCE, + IPV4LL_STATE_ANNOUNCING, + IPV4LL_STATE_RUNNING, + _IPV4LL_STATE_MAX, + _IPV4LL_STATE_INVALID = -1 +} IPv4LLState; + +struct sd_ipv4ll { + IPv4LLState state; + int index; + int fd; + union sockaddr_union link; + int iteration; + int conflict; + sd_event_source *receive_message; + sd_event_source *timer; + usec_t next_wakeup; + usec_t defend_window; + int next_wakeup_valid; + be32_t address; + /* External */ + be32_t claimed_address; + struct ether_addr mac_addr; + sd_event *event; + int event_priority; + sd_ipv4ll_cb_t cb; + void* userdata; +}; + +static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data); + +static void ipv4ll_set_state(sd_ipv4ll *ll, IPv4LLState st, int reset_counter) { + + assert(ll); + assert(st < _IPV4LL_STATE_MAX); + + if (st == ll->state && !reset_counter) { + ll->iteration++; + } else { + ll->state = st; + ll->iteration = 0; + } +} + +static int ipv4ll_client_notify(sd_ipv4ll *ll, int event) { + assert(ll); + + if (ll->cb) + ll->cb(ll, event, ll->userdata); + + return 0; +} + +static int ipv4ll_stop(sd_ipv4ll *ll, int event) { + assert(ll); + + ll->receive_message = sd_event_source_unref(ll->receive_message); + if (ll->fd >= 0) + close_nointr_nofail(ll->fd); + ll->fd = -1; + + ll->timer = sd_event_source_unref(ll->timer); + + ipv4ll_client_notify(ll, event); + + ll->claimed_address = 0; + + ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1); + + log_ipv4ll(ll, "STOPPED"); + + return 0; +} + +static be32_t ipv4ll_pick_address(sd_ipv4ll *ll) { + be32_t addr; + + assert(ll); + + if (ll->address) { + do { + uint32_t r = random_u32() & 0x0000FFFF; + addr = htonl(IPV4LL_NETWORK | r); + } while (addr == ll->address || + (ntohl(addr) & IPV4LL_NETMASK) != IPV4LL_NETWORK || + (ntohl(addr) & 0x0000FF00) == 0x0000 || + (ntohl(addr) & 0x0000FF00) == 0xFF00); + } else { + uint32_t a = 1; + int i; + + for (i = 0; i < ETH_ALEN; i++) + a += ll->mac_addr.ether_addr_octet[i]*i; + a = (a % 0xFE00) + 0x0100; + addr = htonl(IPV4LL_NETWORK | (uint32_t) a); + } + + return addr; +} + +static int ipv4ll_timer(sd_event_source *s, uint64_t usec, void *userdata) { + sd_ipv4ll *ll = (sd_ipv4ll*)userdata; + + assert(ll); + + ll->next_wakeup_valid = 0; + ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_TIMEOUT, NULL); + + return 0; +} + +static void ipv4ll_set_next_wakeup (sd_ipv4ll *ll, int sec, int random_sec) { + usec_t next_timeout = 0; + usec_t time_now = 0; + + assert(sec >= 0); + assert(random_sec >= 0); + assert(ll); + + next_timeout = sec * USEC_PER_SEC; + + if (random_sec) + next_timeout += random_u32() % (random_sec * USEC_PER_SEC); + + if (sd_event_get_now_monotonic(ll->event, &time_now) < 0) + time_now = now(CLOCK_MONOTONIC); + + ll->next_wakeup = time_now + next_timeout; + ll->next_wakeup_valid = 1; +} + +static bool ipv4ll_arp_conflict (sd_ipv4ll *ll, struct ether_arp *arp) { + assert(ll); + assert(arp); + + if (memcmp(arp->arp_spa, &ll->address, sizeof(ll->address)) == 0 && + memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN) != 0) + return true; + + return false; +} + +static bool ipv4ll_arp_probe_conflict (sd_ipv4ll *ll, struct ether_arp *arp) { + assert(ll); + assert(arp); + + if (ipv4ll_arp_conflict(ll, arp)) + return true; + + if (memcmp(arp->arp_tpa, &ll->address, sizeof(ll->address)) == 0 && + memcmp(arp->arp_sha, &ll->mac_addr, ETH_ALEN)) + return true; + + return false; +} + +static void ipv4ll_run_state_machine(sd_ipv4ll *ll, IPv4LLTrigger trigger, void *trigger_data) { + struct ether_arp out_packet; + int out_packet_ready = 0; + int r = 0; + + assert(ll); + assert(trigger < _IPV4LL_TRIGGER_MAX); + + if (ll->state == IPV4LL_STATE_INIT) { + + log_ipv4ll(ll, "PROBE"); + ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1); + ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT); + + } else if ((ll->state == IPV4LL_STATE_WAITING_PROBE && trigger == IPV4LL_TRIGGER_TIMEOUT) || + (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < PROBE_NUM-2)) { + + /* Send a probe */ + arp_packet_probe(&out_packet, ll->address, &ll->mac_addr); + out_packet_ready = 1; + ipv4ll_set_state(ll, IPV4LL_STATE_PROBING, 0); + + ipv4ll_set_next_wakeup(ll, PROBE_MIN, (PROBE_MAX-PROBE_MIN)); + + } else if (ll->state == IPV4LL_STATE_PROBING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration >= PROBE_NUM-2) { + + /* Send the last probe */ + arp_packet_probe(&out_packet, ll->address, &ll->mac_addr); + out_packet_ready = 1; + ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_ANNOUNCE, 1); + + ipv4ll_set_next_wakeup(ll, ANNOUNCE_WAIT, 0); + + } else if ((ll->state == IPV4LL_STATE_WAITING_ANNOUNCE && trigger == IPV4LL_TRIGGER_TIMEOUT) || + (ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT && ll->iteration < ANNOUNCE_NUM-1)) { + + /* Send announcement packet */ + arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr); + out_packet_ready = 1; + ipv4ll_set_state(ll, IPV4LL_STATE_ANNOUNCING, 0); + + ipv4ll_set_next_wakeup(ll, ANNOUNCE_INTERVAL, 0); + + if (ll->iteration == 0) { + log_ipv4ll(ll, "ANNOUNCE"); + ll->claimed_address = ll->address; + r = ipv4ll_client_notify(ll, IPV4LL_EVENT_BIND); + ll->conflict = 0; + } + + } else if ((ll->state == IPV4LL_STATE_ANNOUNCING && trigger == IPV4LL_TRIGGER_TIMEOUT && + ll->iteration >= ANNOUNCE_NUM-1)) { + + ipv4ll_set_state(ll, IPV4LL_STATE_RUNNING, 0); + ll->next_wakeup_valid = 0; + + } else if (trigger == IPV4LL_TRIGGER_PACKET) { + + int conflicted = 0; + usec_t time_now; + struct ether_arp* in_packet = (struct ether_arp*)trigger_data; + + assert(in_packet); + + if (IN_SET(ll->state, IPV4LL_STATE_ANNOUNCING, IPV4LL_STATE_RUNNING)) { + + if (ipv4ll_arp_conflict(ll, in_packet)) { + + r = sd_event_get_now_monotonic(ll->event, &time_now); + if (r < 0) + goto out; + + /* Defend address */ + if (time_now > ll->defend_window) { + ll->defend_window = time_now + DEFEND_INTERVAL * USEC_PER_SEC; + arp_packet_announcement(&out_packet, ll->address, &ll->mac_addr); + out_packet_ready = 1; + } else + conflicted = 1; + } + + } else if (IN_SET(ll->state, IPV4LL_STATE_WAITING_PROBE, + IPV4LL_STATE_PROBING, + IPV4LL_STATE_WAITING_ANNOUNCE)) { + + conflicted = ipv4ll_arp_probe_conflict(ll, in_packet); + } + + if (conflicted) { + log_ipv4ll(ll, "CONFLICT"); + r = ipv4ll_client_notify(ll, IPV4LL_EVENT_CONFLICT); + ll->claimed_address = 0; + + /* Pick a new address */ + ll->address = ipv4ll_pick_address(ll); + ll->conflict++; + ll->defend_window = 0; + ipv4ll_set_state(ll, IPV4LL_STATE_WAITING_PROBE, 1); + + if (ll->conflict >= MAX_CONFLICTS) { + log_ipv4ll(ll, "MAX_CONFLICTS"); + ipv4ll_set_next_wakeup(ll, RATE_LIMIT_INTERVAL, PROBE_WAIT); + } else + ipv4ll_set_next_wakeup(ll, 0, PROBE_WAIT); + + } + } + + if (out_packet_ready) { + r = arp_network_send_raw_socket(ll->fd, &ll->link, &out_packet); + if (r < 0) { + log_ipv4ll(ll, "failed to send arp packet out"); + goto out; + } + } + + if (ll->next_wakeup_valid) { + ll->timer = sd_event_source_unref(ll->timer); + r = sd_event_add_monotonic(ll->event, &ll->timer, + ll->next_wakeup, 0, ipv4ll_timer, ll); + if (r < 0) + goto out; + + r = sd_event_source_set_priority(ll->timer, ll->event_priority); + if (r < 0) + goto out; + } + +out: + if (r < 0) + ipv4ll_stop(ll, r); +} + +static int ipv4ll_receive_message(sd_event_source *s, int fd, + uint32_t revents, void *userdata) { + int r; + struct ether_arp arp; + sd_ipv4ll *ll = (sd_ipv4ll*)userdata; + + assert(ll); + + r = read(fd, &arp, sizeof(struct ether_arp)); + if (r < (int) sizeof(struct ether_arp)) + return 0; + + r = arp_packet_verify_headers(&arp); + if (r < 0) + return 0; + + ipv4ll_run_state_machine(ll, IPV4LL_TRIGGER_PACKET, &arp); + + return 0; +} + +int sd_ipv4ll_set_index(sd_ipv4ll *ll, int interface_index) { + assert_return(ll, -EINVAL); + assert_return(interface_index >= -1, -EINVAL); + assert_return(ll->state == IPV4LL_STATE_INIT, -EBUSY); + + ll->index = interface_index; + + return 0; +} + +int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) { + assert_return(ll, -EINVAL); + assert_return(ll->state == IPV4LL_STATE_INIT, -EBUSY); + + memcpy(&ll->mac_addr.ether_addr_octet, addr, ETH_ALEN); + + return 0; +} + +int sd_ipv4ll_detach_event(sd_ipv4ll *ll) { + assert_return(ll, -EINVAL); + + ll->event = sd_event_unref(ll->event); + + return 0; +} + +int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int priority) { + int r; + + assert_return(ll, -EINVAL); + assert_return(!ll->event, -EBUSY); + + if (event) + ll->event = sd_event_ref(event); + else { + r = sd_event_default(&ll->event); + if (r < 0) { + ipv4ll_stop(ll, IPV4LL_EVENT_STOP); + return r; + } + } + + ll->event_priority = priority; + + return 0; +} + +int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_cb_t cb, void *userdata) { + assert_return(ll, -EINVAL); + + ll->cb = cb; + ll->userdata = userdata; + + return 0; +} + +int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address){ + assert_return(ll, -EINVAL); + assert_return(address, -EINVAL); + + if (ll->claimed_address == 0) { + return -ENOENT; + } + + address->s_addr = ll->claimed_address; + return 0; +} + +int sd_ipv4ll_start (sd_ipv4ll *ll) { + int r; + + assert_return(ll, -EINVAL); + assert_return(ll->event, -EINVAL); + assert_return(ll->index > 0, -EINVAL); + assert_return(ll->state == IPV4LL_STATE_INIT, -EBUSY); + + r = arp_network_bind_raw_socket(ll->index, &ll->link); + + if (r < 0) + goto out; + + ll->fd = r; + ll->conflict = 0; + ll->defend_window = 0; + ll->claimed_address = 0; + + if (ll->address == 0) + ll->address = ipv4ll_pick_address(ll); + + ipv4ll_set_state (ll, IPV4LL_STATE_INIT, 1); + + r = sd_event_add_io(ll->event, &ll->receive_message, ll->fd, + EPOLLIN, ipv4ll_receive_message, ll); + if (r < 0) + goto out; + + r = sd_event_source_set_priority(ll->receive_message, ll->event_priority); + if (r < 0) + goto out; + + r = sd_event_add_monotonic(ll->event, &ll->timer, now(CLOCK_MONOTONIC), 0, + ipv4ll_timer, ll); + + if (r < 0) + goto out; + + r = sd_event_source_set_priority(ll->timer, ll->event_priority); + +out: + if (r < 0) + ipv4ll_stop(ll, IPV4LL_EVENT_STOP); + + return 0; +} + +int sd_ipv4ll_stop(sd_ipv4ll *ll) { + return ipv4ll_stop(ll, IPV4LL_EVENT_STOP); +} + +void sd_ipv4ll_free (sd_ipv4ll *ll) { + if (!ll) + return; + + sd_ipv4ll_stop(ll); + sd_ipv4ll_detach_event(ll); + + free(ll); +} + +DEFINE_TRIVIAL_CLEANUP_FUNC(sd_ipv4ll*, sd_ipv4ll_free); +#define _cleanup_ipv4ll_free_ _cleanup_(sd_ipv4ll_freep) + +int sd_ipv4ll_new(sd_ipv4ll **ret) { + _cleanup_ipv4ll_free_ sd_ipv4ll *ll = NULL; + + assert_return(ret, -EINVAL); + + ll = new0(sd_ipv4ll, 1); + if (!ll) + return -ENOMEM; + + ll->state = IPV4LL_STATE_INIT; + ll->index = -1; + ll->fd = -1; + + *ret = ll; + ll = NULL; + + return 0; +} |