babeld.c

/*
Copyright (c) 2007, 2008 by Juliusz Chroboczek
Copyright (c) 2010 by Vincent Gross
Copyright (c) 2021 by Florian Wiedner

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#include <string.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/time.h>
#include <time.h>
#include <signal.h>
#include <assert.h>

#include <sys/ioctl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/if.h>
#include <arpa/inet.h>

#include "babeld.h"
#include "util.h"
#include "net.h"
#include "kernel.h"
#include "interface.h"
#include "source.h"
#include "neighbour.h"
#include "route.h"
#include "xroute.h"
#include "message.h"
#include "resend.h"
#include "configuration.h"
#include "local.h"
#include "version.h"

struct timeval now;

unsigned char myid[8];
int have_id = 0;
int debug = 0;

int link_detect = 0;
int all_wireless = 0;
int has_ipv6_subtrees = 0;
int default_wireless_hello_interval = -1;
int default_wired_hello_interval = -1;
int resend_delay = -1;
int random_id = 0;
int do_daemonise = 0;
int skip_kernel_setup = 0;
const char *logfile = NULL,
    *pidfile = "/var/run/babeld.pid",
    *state_file = "/var/lib/babel-state";

unsigned char *receive_buffer = NULL;
int receive_buffer_size = 0;

const unsigned char zeroes[16] = {0};
const unsigned char ones[16] =
    {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
     0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};

int protocol_port;
unsigned char protocol_group[16];
int protocol_socket = -1;
int kernel_socket = -1;
static int kernel_routes_changed = 0;
static int kernel_link_changed = 0;
static int kernel_addr_changed = 0;

struct timeval check_neighbours_timeout, check_interfaces_timeout;

static volatile sig_atomic_t exiting = 0, dumping = 0, reopening = 0;

static int accept_local_connections(void);
static void init_signals(void);
static void dump_tables(FILE *out);

static int
kernel_route_notify(struct kernel_route *route, void *closure)
{
    kernel_routes_changed = 1;
    return -1;
}

static int
kernel_addr_notify(struct kernel_addr *addr, void *closure, const unsigned char* tos)
{
    kernel_addr_changed = 1;
    return -1;
}

static int
kernel_link_notify(struct kernel_link *link, void *closure)
{
    struct interface *ifp;
    FOR_ALL_INTERFACES(ifp) {
        if(strcmp(ifp->name, link->ifname) == 0) {
            kernel_link_changed = 1;
            return -1;
        }
    }
    return 0;
}

int
main(int argc, char **argv)
{
    struct sockaddr_in6 sin6;
    int rc, fd, i, opt;
    time_t expiry_time, source_expiry_time, kernel_dump_time;
    const char **config_files = NULL;
    int num_config_files = 0;
    void *vrc;
    unsigned int seed;
    struct interface *ifp;

    gettime(&now);

    rc = read_random_bytes(&seed, sizeof(seed));
    if(rc < 0) {
        perror("read(random)");
        seed = 42;
    }

    seed ^= (now.tv_sec ^ now.tv_usec);
    srandom(seed);

    parse_address("ff02:0:0:0:0:0:1:6", protocol_group, NULL);
    protocol_port = 6696;
    change_smoothing_half_life(4);
    has_ipv6_subtrees = kernel_has_ipv6_subtrees();

    while(1) {
        opt = getopt(argc, argv,
                     "m:p:h:H:i:k:A:srS:d:g:G:lwz:M:t:T:c:C:DL:I:V");
        if(opt < 0)
            break;

        switch(opt) {
        case 'm':
            rc = parse_address(optarg, protocol_group, NULL);
            if(rc < 0)
                goto usage;
            if(protocol_group[0] != 0xff) {
                fprintf(stderr,
                        "%s is not a multicast address\n", optarg);
                goto usage;
            }
            if(protocol_group[1] != 2) {
                fprintf(stderr,
                        "Warning: %s is not a link-local multicast address\n",
                        optarg);
            }
            break;
        case 'p':
            protocol_port = parse_nat(optarg);
            if(protocol_port <= 0 || protocol_port > 0xFFFF)
                goto usage;
            break;
        case 'h':
            default_wireless_hello_interval = parse_thousands(optarg);
            if(default_wireless_hello_interval <= 0 ||
               default_wireless_hello_interval > 0xFFFF * 10)
                goto usage;
            break;
        case 'H':
            default_wired_hello_interval = parse_thousands(optarg);
            if(default_wired_hello_interval <= 0 ||
               default_wired_hello_interval > 0xFFFF * 10)
                goto usage;
            break;
        case 'k':
            kernel_metric = parse_nat(optarg);
            if(kernel_metric < 0 || kernel_metric > 0xFFFF)
                goto usage;
            break;
        case 'A':
            allow_duplicates = parse_nat(optarg);
            if(allow_duplicates < 0 || allow_duplicates > 0xFFFF)
                goto usage;
            break;
        case 's':
            split_horizon = 0;
            break;
        case 'r':
            random_id = 1;
            break;
        case 'S':
            state_file = optarg;
            break;
        case 'd':
            debug = parse_nat(optarg);
            if(debug < 0)
                goto usage;
            break;
        case 'g':
        case 'G':
            if(opt == 'g')
                local_server_write = 0;
            else
                local_server_write = 1;
            if(optarg[0] == '/') {
                local_server_port = -1;
                free(local_server_path);
                local_server_path = strdup(optarg);
            } else {
                local_server_port = parse_nat(optarg);
                free(local_server_path);
                local_server_path = NULL;
                if(local_server_port <= 0 || local_server_port > 0xFFFF)
                    goto usage;
            }
            break;
        case 'l':
            link_detect = 1;
            break;
        case 'w':
            all_wireless = 1;
            break;
        case 'z':
            {
                char *comma;
                diversity_kind = (int)strtol(optarg, &comma, 0);
                if(*comma == '\0')
                    diversity_factor = 128;
                else if(*comma == ',')
                    diversity_factor = parse_nat(comma + 1);
                else
                    goto usage;
                if(diversity_factor <= 0 || diversity_factor > 256)
                    goto usage;
            }
            break;
        case 'M': {
            int l = parse_nat(optarg);
            if(l < 0 || l > 3600)
                goto usage;
            change_smoothing_half_life(l);
            break;
        }
        case 't':
            export_table = parse_nat(optarg);
            if(export_table < 0 || export_table > 0xFFFF)
                goto usage;
            break;
        case 'T':
            if(add_import_table(parse_nat(optarg)))
                goto usage;
            break;
        case 'c':
            config_files = realloc(config_files,
                                   (num_config_files + 1) * sizeof(char*));
            if(config_files == NULL) {
                fprintf(stderr, "Couldn't allocate config file.\n");
                exit(1);
            }
            config_files[num_config_files++] = optarg;
            break;
        case 'C':
            rc = parse_config_from_string(optarg, strlen(optarg), NULL);
            if(rc != CONFIG_ACTION_DONE) {
                fprintf(stderr,
                        "Couldn't parse configuration from command line.\n");
                exit(1);
            }
            break;
        case 'D':
            do_daemonise = 1;
            break;
        case 'L':
            logfile = optarg;
            break;
        case 'I':
            pidfile = optarg;
            break;
        case 'V':
            fprintf(stderr, "%s\n", BABELD_VERSION);
            exit(0);
            break;
        default:
            goto usage;
        }
    }

    if(num_config_files == 0) {
        if(access("/etc/babeld.conf", F_OK) >= 0) {
            config_files = malloc(sizeof(char*));
            if(config_files == NULL) {
                fprintf(stderr, "Couldn't allocate config file.\n");
                exit(1);
            }
            config_files[num_config_files++] = "/etc/babeld.conf";
        }
    }

    for(i = 0; i < num_config_files; i++) {
        int line;
        rc = parse_config_from_file(config_files[i], &line);
        if(rc < 0) {
            fprintf(stderr,
                    "Couldn't parse configuration from file %s "
                    "(error at line %d).\n",
                    config_files[i], line);
            exit(1);
        }
    }

    free(config_files);

    if(default_wireless_hello_interval <= 0)
        default_wireless_hello_interval = 4000;
    default_wireless_hello_interval = MAX(default_wireless_hello_interval, 5);

    if(default_wired_hello_interval <= 0)
        default_wired_hello_interval = 4000;
    default_wired_hello_interval = MAX(default_wired_hello_interval, 5);

    resend_delay = 2000;
    resend_delay = MIN(resend_delay, default_wireless_hello_interval / 2);
    resend_delay = MIN(resend_delay, default_wired_hello_interval / 2);
    resend_delay = MAX(resend_delay, 20);

    if(do_daemonise) {
        if(logfile == NULL)
            logfile = "/var/log/babeld.log";
    }

    rc = reopen_logfile();
    if(rc < 0) {
        perror("reopen_logfile()");
        exit(1);
    }

    fd = open("/dev/null", O_RDONLY);
    if(fd < 0) {
        perror("open(null)");
        exit(1);
    }

    rc = dup2(fd, 0);
    if(rc < 0) {
        perror("dup2(null, 0)");
        exit(1);
    }

    close(fd);

    if(do_daemonise) {
        rc = daemonise();
        if(rc < 0) {
            perror("daemonise");
            exit(1);
        }
    }

    if(pidfile && pidfile[0] != '\0') {
        int pfd, len;
        char buf[100];

        len = snprintf(buf, 100, "%lu", (unsigned long)getpid());
        if(len < 0 || len >= 100) {
            perror("snprintf(getpid)");
            exit(1);
        }

        pfd = open(pidfile, O_WRONLY | O_CREAT | O_EXCL, 0644);
        if(pfd < 0) {
            char buf[40];
            snprintf(buf, 40, "creat(%s)", pidfile);
            buf[39] = '\0';
            perror(buf);
            exit(1);
        }

        rc = write(pfd, buf, len);
        if(rc < len) {
            perror("write(pidfile)");
            goto fail_pid;
        }

        close(pfd);
    }

    rc = kernel_setup(1);
    if(rc < 0) {
        fprintf(stderr, "kernel_setup failed.\n");
        goto fail_pid;
    }

    rc = kernel_setup_socket(1);
    if(rc < 0) {
        fprintf(stderr, "kernel_setup_socket failed.\n");
        kernel_setup(0);
        goto fail_pid;
    }

    rc = finalise_config();
    if(rc < 0) {
        fprintf(stderr, "Couldn't finalise configuration.\n");
        goto fail;
    }

    for(i = optind; i < argc; i++) {
        vrc = add_interface(argv[i], NULL);
        if(vrc == NULL)
            goto fail;
    }

    if(interfaces == NULL) {
        fprintf(stderr, "Eek... asked to run on no interfaces!\n");
        goto fail;
    }

    if(!have_id && !random_id) {
        /* We use all available interfaces here, since this increases the
           chances of getting a stable router-id in case the set of Babel
           interfaces changes. */

        for(i = 1; i < 256; i++) {
            char buf[IF_NAMESIZE], *ifname;
            unsigned char eui[8];
            ifname = if_indextoname(i, buf);
            if(ifname == NULL)
                continue;
            rc = if_eui64(ifname, i, eui);
            if(rc < 0)
                continue;
            memcpy(myid, eui, 8);
            have_id = 1;
            break;
        }
    }

    if(!have_id) {
        if(!random_id)
            fprintf(stderr,
                    "Warning: couldn't find router id -- "
                    "using random value.\n");
        rc = read_random_bytes(myid, 8);
        if(rc < 0) {
            perror("read(random)");
            goto fail;
        }
        /* Clear group and global bits */
        myid[0] &= ~3;
    }

    myseqno = (random() & 0xFFFF);

    fd = open(state_file, O_RDONLY);
    if(fd < 0 && errno != ENOENT)
        perror("open(babel-state)");
    rc = unlink(state_file);
    if(fd >= 0 && rc < 0) {
        perror("unlink(babel-state)");
        /* If we couldn't unlink it, it's probably stale. */
        close(fd);
        fd = -1;
    }
    if(fd >= 0) {
        char buf[100];
        int s;
        rc = read(fd, buf, 99);
        if(rc < 0) {
            perror("read(babel-state)");
        } else {
            buf[rc] = '\0';
            rc = sscanf(buf, "%d\n", &s);
            if(rc == 1 && s >= 0 && s <= 0xFFFF) {
                myseqno = seqno_plus(s, 1);
            } else {
                fprintf(stderr, "Couldn't parse babel-state.\n");
            }
        }
        close(fd);
        fd = -1;
    }

    protocol_socket = babel_socket(protocol_port);
    if(protocol_socket < 0) {
        perror("Couldn't create link local socket");
        goto fail;
    }

    if(local_server_port >= 0) {
        local_server_socket = tcp_server_socket(local_server_port, 1);
        if(local_server_socket < 0) {
            perror("local_server_socket");
            goto fail;
        }
    } else if(local_server_path) {
        local_server_socket = unix_server_socket(local_server_path);
        if(local_server_socket < 0) {
            perror("local_server_socket");
            goto fail;
        }
    }

    init_signals();
    rc = resize_receive_buffer(1500);
    if(rc < 0)
        goto fail;
    if(receive_buffer == NULL)
        goto fail;

    check_interfaces();

    rc = check_xroutes(0);
    if(rc < 0)
        fprintf(stderr, "Warning: couldn't check exported routes.\n");

    kernel_routes_changed = 0;
    kernel_link_changed = 0;
    kernel_addr_changed = 0;
    kernel_dump_time = now.tv_sec + roughly(30);
    schedule_neighbours_check(5000, 1);
    schedule_interfaces_check(30000, 1);
    expiry_time = now.tv_sec + roughly(30);
    source_expiry_time = now.tv_sec + roughly(300);

    /* Make some noise so that others notice us, and send retractions in
       case we were restarted recently */
    FOR_ALL_INTERFACES(ifp) {
        if(!if_up(ifp))
            continue;
        /* Apply jitter before we send the first message. */
        usleep(roughly(10000));
        gettime(&now);
        send_hello(ifp);
        send_wildcard_retraction(ifp);
        flushupdates(ifp);
        flushbuf(&ifp->buf, ifp);
    }

    FOR_ALL_INTERFACES(ifp) {
        if(!if_up(ifp))
            continue;
        usleep(roughly(10000));
        gettime(&now);
        send_hello(ifp);
        send_wildcard_retraction(ifp);
        send_self_update(ifp);
        send_multicast_request(ifp, NULL, 0, NULL, 0, NULL);
        flushupdates(ifp);
        flushbuf(&ifp->buf, ifp);
    }

    debugf("Entering main loop.\n");

    while(1) {
        struct timeval tv;
        fd_set readfds;
        struct neighbour *neigh;

        gettime(&now);

        tv = check_neighbours_timeout;
        timeval_min(&tv, &check_interfaces_timeout);
        timeval_min_sec(&tv, expiry_time);
        timeval_min_sec(&tv, source_expiry_time);
        timeval_min_sec(&tv, kernel_dump_time);
        timeval_min(&tv, &resend_time);
        FOR_ALL_INTERFACES(ifp) {
            if(!if_up(ifp))
                continue;
            timeval_min(&tv, &ifp->buf.timeout);
            timeval_min(&tv, &ifp->hello_timeout);
            timeval_min(&tv, &ifp->update_timeout);
            timeval_min(&tv, &ifp->update_flush_timeout);
        }
        FOR_ALL_NEIGHBOURS(neigh) {
            timeval_min(&tv, &neigh->buf.timeout);
        }
        FD_ZERO(&readfds);
        if(timeval_compare(&tv, &now) > 0) {
            int maxfd = 0;
            timeval_minus(&tv, &tv, &now);
            FD_SET(protocol_socket, &readfds);
            maxfd = MAX(maxfd, protocol_socket);
            if(kernel_socket < 0) kernel_setup_socket(1);
            if(kernel_socket >= 0) {
                FD_SET(kernel_socket, &readfds);
                maxfd = MAX(maxfd, kernel_socket);
            }
            if(local_server_socket >= 0 &&
               num_local_sockets < MAX_LOCAL_SOCKETS) {
                FD_SET(local_server_socket, &readfds);
                maxfd = MAX(maxfd, local_server_socket);
            }
            for(i = 0; i < num_local_sockets; i++) {
                FD_SET(local_sockets[i].fd, &readfds);
                maxfd = MAX(maxfd, local_sockets[i].fd);
            }
            rc = select(maxfd + 1, &readfds, NULL, NULL, &tv);
            if(rc < 0) {
                if(errno != EINTR) {
                    perror("select");
                    sleep(1);
                }
                rc = 0;
                FD_ZERO(&readfds);
            }
        }

        gettime(&now);

        if(exiting)
            break;

        if(kernel_socket >= 0 && FD_ISSET(kernel_socket, &readfds)) {
            struct kernel_filter filter = {0};
            filter.route = kernel_route_notify;
            filter.addr = kernel_addr_notify;
            filter.link = kernel_link_notify;
            kernel_callback(&filter);
        }

        if(FD_ISSET(protocol_socket, &readfds)) {
            unsigned char to[16];
            rc = babel_recv(protocol_socket,
                            receive_buffer, receive_buffer_size,
                            (struct sockaddr*)&sin6, sizeof(sin6), to);
            if(rc < 0) {
                if(errno != EAGAIN && errno != EINTR) {
                    perror("recv");
                    sleep(1);
                }
            } else {
                FOR_ALL_INTERFACES(ifp) {
                    if(!if_up(ifp))
                        continue;
                    if(ifp->ifindex == sin6.sin6_scope_id) {
                        parse_packet((unsigned char*)&sin6.sin6_addr, ifp,
                                     receive_buffer, rc, to);
                        VALGRIND_MAKE_MEM_UNDEFINED(receive_buffer,
                                                    receive_buffer_size);
                        break;
                    }
                }
            }
        }

        if(local_server_socket >= 0 && FD_ISSET(local_server_socket, &readfds))
           accept_local_connections();

        i = 0;
        while(i < num_local_sockets) {
            if(FD_ISSET(local_sockets[i].fd, &readfds)) {
                rc = local_read(&local_sockets[i]);
                if(rc <= 0) {
                    if(rc < 0) {
                        if(errno == EINTR || errno == EAGAIN)
                            continue;
                        perror("read(local_socket)");
                    }
                    local_socket_destroy(i);
                }
            }
            i++;
        }

        if(reopening) {
            kernel_dump_time = now.tv_sec;
            check_neighbours_timeout = now;
            expiry_time = now.tv_sec;
            rc = reopen_logfile();
            if(rc < 0) {
                perror("reopen_logfile");
                break;
            }
            reopening = 0;
        }

        if(kernel_link_changed || kernel_addr_changed) {
            check_interfaces();
            kernel_link_changed = 0;
        }

        if(kernel_routes_changed || kernel_addr_changed ||
           now.tv_sec >= kernel_dump_time) {
            rc = check_xroutes(1);
            if(rc < 0)
                fprintf(stderr, "Warning: couldn't check exported routes.\n");
            kernel_routes_changed = kernel_addr_changed = 0;
            if(kernel_socket >= 0)
                kernel_dump_time = now.tv_sec + roughly(300);
            else
                kernel_dump_time = now.tv_sec + roughly(30);
        }

        if(timeval_compare(&check_neighbours_timeout, &now) < 0) {
            int msecs;
            msecs = check_neighbours();
            /* Multiply by 3/2 to allow neighbours to expire. */
            msecs = MAX(3 * msecs / 2, 10);
            schedule_neighbours_check(msecs, 1);
        }

        if(timeval_compare(&check_interfaces_timeout, &now) < 0) {
            check_interfaces();
            schedule_interfaces_check(30000, 1);
        }

        if(now.tv_sec >= expiry_time) {
            expire_routes();
            expire_resend();
            expiry_time = now.tv_sec + roughly(30);
        }

        if(now.tv_sec >= source_expiry_time) {
            expire_sources();
            source_expiry_time = now.tv_sec + roughly(300);
        }

        FOR_ALL_INTERFACES(ifp) {
            if(!if_up(ifp))
                continue;
            if(timeval_compare(&now, &ifp->hello_timeout) >= 0)
                send_hello(ifp);
            if(timeval_compare(&now, &ifp->update_timeout) >= 0)
                send_update(ifp, 0, NULL, 0, NULL, 0, NULL);
            if(timeval_compare(&now, &ifp->update_flush_timeout) >= 0)
                flushupdates(ifp);
        }

        if(resend_time.tv_sec != 0) {
            if(timeval_compare(&now, &resend_time) >= 0)
                do_resend();
        }

        FOR_ALL_INTERFACES(ifp) {
            if(!if_up(ifp))
                continue;
            if(ifp->buf.timeout.tv_sec != 0) {
                if(timeval_compare(&now, &ifp->buf.timeout) >= 0) {
                    flushupdates(ifp);
                    flushbuf(&ifp->buf, ifp);
                }
            }
        }

        FOR_ALL_NEIGHBOURS(neigh) {
            if(neigh->buf.timeout.tv_sec != 0) {
                if(timeval_compare(&now, &neigh->buf.timeout) >= 0) {
                    flushbuf(&neigh->buf, neigh->ifp);
                }
            }
        }

        if(UNLIKELY(debug || dumping)) {
            dump_tables(stdout);
            dumping = 0;
        }
    }

    debugf("Exiting...\n");
    usleep(roughly(10000));
    gettime(&now);

    /* We need to flush so interface_updown won't try to reinstall. */
    flush_all_routes();

    FOR_ALL_INTERFACES(ifp) {
        if(!if_up(ifp))
            continue;
        send_wildcard_retraction(ifp);
        /* Make sure that we expire quickly from our neighbours'
           association caches. */
        send_multicast_hello(ifp, 10, 1);
        flushbuf(&ifp->buf, ifp);
        usleep(roughly(1000));
        gettime(&now);
    }
    FOR_ALL_INTERFACES(ifp) {
        if(!if_up(ifp))
            continue;
        /* Make sure they got it. */
        send_wildcard_retraction(ifp);
        send_multicast_hello(ifp, 1, 1);
        flushbuf(&ifp->buf, ifp);
        usleep(roughly(10000));
        gettime(&now);
        interface_updown(ifp, 0);
    }
    kernel_setup_socket(0);
    kernel_setup(0);

    fd = open(state_file, O_WRONLY | O_TRUNC | O_CREAT, 0644);
    if(fd < 0) {
        perror("creat(babel-state)");
        unlink(state_file);
    } else {
        char buf[10];
        rc = snprintf(buf, 10, "%d\n", (int)myseqno);
        if(rc < 0 || rc >= 10) {
            fprintf(stderr, "write(babel-state): overflow.\n");
            unlink(state_file);
        } else {
            rc = write(fd, buf, rc);
            if(rc < 0) {
                perror("write(babel-state)");
                unlink(state_file);
            }
            fsync(fd);
        }
        close(fd);
    }
    if(local_server_socket >= 0 && local_server_path) {
        unlink(local_server_path);
        free(local_server_path);
    }
    if(pidfile)
        unlink(pidfile);
    debugf("Done.\n");
    return 0;

 usage:
    fprintf(stderr,
            "%s\n"
            "Syntax: babeld "
            "[-V] [-m multicast_address] [-p port] [-S state-file]\n"
            "               "
            "[-h hello] [-H wired_hello] [-z kind[,factor]]\n"
            "               "
            "[-g port] [-G port] [-k metric] [-A metric] [-s] [-l] [-w] [-r]\n"
            "               "
            "[-t table] [-T table] [-c file] [-C statement]\n"
            "               "
            "[-d level] [-D] [-L logfile] [-I pidfile]\n"
            "               "
            "interface...\n",
            BABELD_VERSION);
    exit(1);

 fail:
    FOR_ALL_INTERFACES(ifp) {
        if(!if_up(ifp))
            continue;
        interface_updown(ifp, 0);
    }
    kernel_setup_socket(0);
    kernel_setup(0);
 fail_pid:
    if(pidfile)
        unlink(pidfile);
    exit(1);
}

static int
accept_local_connections()
{
    int rc, s;
    struct local_socket *ls;

    if(local_server_socket < 0)
        return 0;

    s = accept(local_server_socket, NULL, NULL);

    if(s < 0) {
        if(errno != EINTR && errno != EAGAIN) {
            perror("accept(local_server_socket)");
            return -1;
        }
        return 0;
    }

    if(num_local_sockets >= MAX_LOCAL_SOCKETS) {
        /* This should never happen, since we don't select for
           the server socket in this case.  But I'm paranoid. */
        fprintf(stderr, "Internal error: too many local sockets.\n");
        close(s);
        return -1;
    }

    rc = fcntl(s, F_GETFL, 0);
    if(rc < 0) {
        fprintf(stderr, "Unable to get flags of local socket.\n");
        close(s);
        return -1;
    }

    rc = fcntl(s, F_SETFL, (rc | O_NONBLOCK));
    if(rc < 0) {
        fprintf(stderr, "Unable to set flags of local socket.\n");
        close(s);
        return -1;
    }

    ls = local_socket_create(s);
    if(ls == NULL) {
        fprintf(stderr, "Unable create local socket.\n");
        close(s);
        return -1;
    }
    local_header(ls);
    return 1;
}

void
schedule_neighbours_check(int msecs, int override)
{
    struct timeval timeout;

    timeval_add_msec(&timeout, &now, roughly(msecs));
    if(override)
        check_neighbours_timeout = timeout;
    else
        timeval_min(&check_neighbours_timeout, &timeout);
}

void
schedule_interfaces_check(int msecs, int override)
{
    struct timeval timeout;

    timeval_add_msec(&timeout, &now, roughly(msecs));
    if(override)
        check_interfaces_timeout = timeout;
    else
        timeval_min(&check_interfaces_timeout, &timeout);
}

int
resize_receive_buffer(int size)
{
    unsigned char *new;

    if(size <= receive_buffer_size)
        return 0;

    new = realloc(receive_buffer, size);
    if(new == NULL) {
        perror("realloc(receive_buffer)");
        return -1;
    }
    receive_buffer = new;
    receive_buffer_size = size;

    return 1;
}

static void
sigexit(int signo)
{
    exiting = 1;
}

static void
sigdump(int signo)
{
    dumping = 1;
}

static void
sigreopening(int signo)
{
    reopening = 1;
}

static void
init_signals(void)
{
    struct sigaction sa;
    sigset_t ss;

    sigemptyset(&ss);
    sa.sa_handler = sigexit;
    sa.sa_mask = ss;
    sa.sa_flags = 0;
    sigaction(SIGTERM, &sa, NULL);

    sigemptyset(&ss);
    sa.sa_handler = sigexit;
    sa.sa_mask = ss;
    sa.sa_flags = 0;
    sigaction(SIGHUP, &sa, NULL);

    sigemptyset(&ss);
    sa.sa_handler = sigexit;
    sa.sa_mask = ss;
    sa.sa_flags = 0;
    sigaction(SIGINT, &sa, NULL);

    sigemptyset(&ss);
    sa.sa_handler = SIG_IGN;
    sa.sa_mask = ss;
    sa.sa_flags = 0;
    sigaction(SIGPIPE, &sa, NULL);

    sigemptyset(&ss);
    sa.sa_handler = sigdump;
    sa.sa_mask = ss;
    sa.sa_flags = 0;
    sigaction(SIGUSR1, &sa, NULL);

    sigemptyset(&ss);
    sa.sa_handler = sigreopening;
    sa.sa_mask = ss;
    sa.sa_flags = 0;
    sigaction(SIGUSR2, &sa, NULL);

#ifdef SIGINFO
    sigemptyset(&ss);
    sa.sa_handler = sigdump;
    sa.sa_mask = ss;
    sa.sa_flags = 0;
    sigaction(SIGINFO, &sa, NULL);
#endif
}

static void
dump_route(FILE *out, struct babel_route *route)
{
    const unsigned char *nexthop =
        memcmp(route->nexthop, route->neigh->address, 16) == 0 ?
        NULL : route->nexthop;
    char channels[100];

    if(route->channels_len == 0) {
        channels[0] = '\0';
    } else {
        int k, j = 0;
        snprintf(channels, 100, " chan (");
        j = strlen(channels);
        for(k = 0; k < route->channels_len; k++) {
            if(k > 0)
                channels[j++] = ',';
            snprintf(channels + j, 100 - j, "%u", (unsigned)route->channels[k]);
            j = strlen(channels);
        }
        snprintf(channels + j, 100 - j, ")");
    }

    fprintf(out, "%s from %s tos %s metric %d (%d) refmetric %d id %s "
            "seqno %d%s age %d via %s neigh %s%s%s%s\n",
            format_prefix(route->src->prefix, route->src->plen),
            format_prefix(route->src->src_prefix, route->src->src_plen),
            format_tos_value(route->src->tos),
            route_metric(route), route_smoothed_metric(route), route->refmetric,
            format_eui64(route->src->id),
            (int)route->seqno,
            channels,
            (int)(now.tv_sec - route->time),
            route->neigh->ifp->name,
            format_address(route->neigh->address),
            nexthop ? " nexthop " : "",
            nexthop ? format_address(nexthop) : "",
            route->installed ? " (installed)" :
            route_feasible(route) ? " (feasible)" : "");
}

static void
dump_xroute(FILE *out, struct xroute *xroute)
{
    fprintf(out, "%s from %s metric %d (exported)\n",
            format_prefix(xroute->prefix, xroute->plen),
            format_prefix(xroute->src_prefix, xroute->src_plen),
            xroute->metric);
}

static void
dump_tables(FILE *out)
{
    struct neighbour *neigh;
    struct xroute_stream *xroutes;
    struct route_stream *routes;

    fprintf(out, "\n");

    fprintf(out, "My id %s seqno %d\n", format_eui64(myid), myseqno);

    FOR_ALL_NEIGHBOURS(neigh) {
        fprintf(out, "Neighbour %s dev %s reach %04x ureach %04x "
                "rxcost %u txcost %d rtt %s rttcost %u chan %d%s.\n",
                format_address(neigh->address),
                neigh->ifp->name,
                neigh->hello.reach,
                neigh->uhello.reach,
                neighbour_rxcost(neigh),
                neigh->txcost,
                format_thousands(neigh->rtt),
                neighbour_rttcost(neigh, DSCP_DF), //Use default value here
                neigh->ifp->channel,
                if_up(neigh->ifp) ? "" : " (down)");
    }

    xroutes = xroute_stream();
    if(xroutes) {
        while(1) {
            struct xroute *xroute = xroute_stream_next(xroutes);
            if(xroute == NULL) break;
            dump_xroute(out, xroute);
        }
        xroute_stream_done(xroutes);
    }

    routes = route_stream(0);
    if(routes) {
        while(1) {
            struct babel_route *route = route_stream_next(routes);
            if(route == NULL) break;
            dump_route(out, route);
        }
        route_stream_done(routes);
    }

    fflush(out);
}

int
reopen_logfile()
{
    int lfd, rc;

    if(logfile == NULL)
        return 0;

    lfd = open(logfile, O_CREAT | O_WRONLY | O_APPEND, 0644);
    if(lfd < 0)
        return -1;

    fflush(stdout);
    fflush(stderr);

    rc = dup2(lfd, 1);
    if(rc < 0)
        return -1;

    rc = dup2(lfd, 2);
    if(rc < 0)
        return -1;

    if(lfd > 2)
        close(lfd);

    return 1;
}