babeld: Initial import, for Babel routing protocol.

* Initial import of the Babel routing protocol, ported to Quagga.
* LICENCE: Update the original LICENCE file to include all known potentially
  applicable copyright claims.  Ask that any future contributors to babeld/
  grant MIT/X11 licence to their work.
* *.{c,h}: Add GPL headers, in according with the SFLC guidance on
  dealing with potentially mixed GPL/other licensed work, at:

  https://www.softwarefreedom.org/resources/2007/gpl-non-gpl-collaboration.html

1 files changed, 778 insertions, 0 deletions

diff --git a/babeld/babel_interface.c b/babeld/babel_interface.c
new file mode 100644
index 00000000..0130f26b
--- /dev/null
+++ b/babeld/babel_interface.c
@@ -0,0 +1,778 @@
+/*  
+ *  This file is free software: you may copy, redistribute and/or modify it  
+ *  under the terms of the GNU General Public License as published by the  
+ *  Free Software Foundation, either version 2 of the License, or (at your  
+ *  option) any later version.  
+ *  
+ *  This file 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  
+ *  General Public License for more details.  
+ *  
+ *  You should have received a copy of the GNU General Public License  
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.  
+ *  
+ * This file incorporates work covered by the following copyright and  
+ * permission notice:  
+ *  
+
+Copyright 2011 by Matthieu Boutier and Juliusz Chroboczek
+
+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 <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <sys/time.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <net/if.h>
+#include <arpa/inet.h>
+
+#include <zebra.h>
+#include "memory.h"
+#include "log.h"
+#include "command.h"
+#include "prefix.h"
+#include "vector.h"
+
+#include "babel_main.h"
+#include "util.h"
+#include "kernel.h"
+#include "babel_interface.h"
+#include "message.h"
+#include "route.h"
+#include "babel_zebra.h"
+
+
+static int babel_enable_if_lookup (const char *ifname);
+static int babel_enable_if_add (const char *ifname);
+static int babel_enable_if_delete (const char *ifname);
+static int interface_recalculate(struct interface *ifp);
+static int interface_reset(struct interface *ifp);
+static int babel_if_new_hook    (struct interface *ifp);
+static int babel_if_delete_hook (struct interface *ifp);
+static int interface_config_write (struct vty *vty);
+static babel_interface_nfo * babel_interface_allocate ();
+static void babel_interface_free (babel_interface_nfo *bi);
+
+
+static vector babel_enable_if;                 /* enable interfaces (by cmd). */
+static struct cmd_node babel_interface_node =  /* babeld's interface node.    */
+{
+    INTERFACE_NODE,
+    "%s(config-if)# ",
+    1 /* VTYSH */
+};
+
+
+int
+babel_interface_up (int cmd, struct zclient *client, zebra_size_t length)
+{
+    struct stream *s = NULL;
+    struct interface *ifp = NULL;
+
+    debugf(BABEL_DEBUG_IF, "receive a 'interface up'");
+
+    s = zclient->ibuf;
+    ifp = zebra_interface_state_read(s);
+
+    if (ifp == NULL) {
+        return 0;
+    }
+
+    interface_recalculate(ifp);
+    return 0;
+}
+
+int
+babel_interface_down (int cmd, struct zclient *client, zebra_size_t length)
+{
+    struct stream *s = NULL;
+    struct interface *ifp = NULL;
+
+    debugf(BABEL_DEBUG_IF, "receive a 'interface down'");
+
+    s = zclient->ibuf;
+    ifp = zebra_interface_state_read(s);
+
+    if (ifp == NULL) {
+        return 0;
+    }
+
+    interface_reset(ifp);
+    return 0;
+}
+
+int
+babel_interface_add (int cmd, struct zclient *client, zebra_size_t length)
+{
+    struct interface *ifp = NULL;
+
+    debugf(BABEL_DEBUG_IF, "receive a 'interface add'");
+
+    /* read and add the interface in the iflist. */
+    ifp = zebra_interface_add_read (zclient->ibuf);
+
+    if (ifp == NULL) {
+        return 0;
+    }
+
+    interface_recalculate(ifp);
+
+    return 0;
+}
+
+int
+babel_interface_delete (int cmd, struct zclient *client, zebra_size_t length)
+{
+    debugf(BABEL_DEBUG_IF, "receive a 'interface delete'");
+    return 0;
+}
+
+int
+babel_interface_address_add (int cmd, struct zclient *client,
+                             zebra_size_t length)
+{
+    babel_interface_nfo *babel_ifp;
+    struct connected *ifc;
+    struct prefix *prefix;
+
+    debugf(BABEL_DEBUG_IF, "receive a 'interface address add'");
+
+    ifc = zebra_interface_address_read (ZEBRA_INTERFACE_ADDRESS_ADD,
+                                        zclient->ibuf);
+
+    if (ifc == NULL)
+        return 0;
+
+    prefix = ifc->address;
+
+    if (prefix->family == AF_INET) {
+        flush_interface_routes(ifc->ifp, 0);
+        babel_ifp = babel_get_if_nfo(ifc->ifp);
+        if (babel_ifp->ipv4 == NULL) {
+            babel_ifp->ipv4 = malloc(4);
+            if (babel_ifp->ipv4 == NULL) {
+                zlog_err("not einough memory");
+            } else {
+                memcpy(babel_ifp->ipv4, &prefix->u.prefix4, 4);
+            }
+        }
+    }
+
+    send_request(ifc->ifp, NULL, 0);
+    send_update(ifc->ifp, 0, NULL, 0);
+
+    return 0;
+}
+
+int
+babel_interface_address_delete (int cmd, struct zclient *client,
+                                zebra_size_t length)
+{
+    babel_interface_nfo *babel_ifp;
+    struct connected *ifc;
+    struct prefix *prefix;
+
+    debugf(BABEL_DEBUG_IF, "receive a 'interface address add'");
+
+    ifc = zebra_interface_address_read (ZEBRA_INTERFACE_ADDRESS_ADD,
+                                        zclient->ibuf);
+
+    if (ifc == NULL)
+        return 0;
+
+    prefix = ifc->address;
+
+    if (prefix->family == AF_INET) {
+        flush_interface_routes(ifc->ifp, 0);
+        babel_ifp = babel_get_if_nfo(ifc->ifp);
+        if (babel_ifp->ipv4 != NULL
+            && memcmp(babel_ifp->ipv4, &prefix->u.prefix4, 4) == 0) {
+            free(babel_ifp->ipv4);
+            babel_ifp->ipv4 = NULL;
+        }
+    }
+
+    send_request(ifc->ifp, NULL, 0);
+    send_update(ifc->ifp, 0, NULL, 0);
+
+    return 0;
+}
+
+/* Lookup function. */
+static int
+babel_enable_if_lookup (const char *ifname)
+{
+    unsigned int i;
+    char *str;
+
+    for (i = 0; i < vector_active (babel_enable_if); i++)
+        if ((str = vector_slot (babel_enable_if, i)) != NULL)
+            if (strcmp (str, ifname) == 0)
+                return i;
+    return -1;
+}
+
+/* Add interface to babel_enable_if. */
+static int
+babel_enable_if_add (const char *ifname)
+{
+    int ret;
+    struct interface *ifp = NULL;
+
+    ret = babel_enable_if_lookup (ifname);
+    if (ret >= 0)
+        return -1;
+
+    vector_set (babel_enable_if, strdup (ifname));
+
+    ifp = if_lookup_by_name(ifname);
+    if (ifp != NULL)
+        babel_get_if_nfo(ifp)->flags |= BABEL_IF_IS_ENABLE;
+
+    return 1;
+}
+
+/* Delete interface from babel_enable_if. */
+static int
+babel_enable_if_delete (const char *ifname)
+{
+    int babel_enable_if_index;
+    char *str;
+    struct interface *ifp = NULL;
+
+    babel_enable_if_index = babel_enable_if_lookup (ifname);
+    if (babel_enable_if_index < 0)
+        return -1;
+
+    str = vector_slot (babel_enable_if, babel_enable_if_index);
+    free (str);
+    vector_unset (babel_enable_if, babel_enable_if_index);
+
+    ifp = if_lookup_by_name(ifname);
+    if (ifp != NULL)
+        babel_get_if_nfo(ifp)->flags &= ~BABEL_IF_IS_ENABLE;
+
+    return 1;
+}
+
+
+/* [Babel Command] Babel enable on specified interface or matched network. */
+DEFUN (babel_network,
+       babel_network_cmd,
+       "network IF_OR_ADDR",
+       "Babel enable on specified interface or network.\n"
+       "Interface or address")
+{
+    int ret;
+    struct prefix p;
+
+    ret = str2prefix (argv[0], &p);
+
+    /* Given string is:               */
+    if (ret) /* an IPv4 or v6 network */
+        return CMD_ERR_NO_MATCH; /* not implemented yet */
+    else     /* an interface name     */
+        ret = babel_enable_if_add (argv[0]);
+
+    if (ret < 0) {
+        vty_out (vty, "There is same network configuration %s%s", argv[0],
+                 VTY_NEWLINE);
+        return CMD_WARNING;
+    }
+
+    return CMD_SUCCESS;
+}
+
+/* [Babel Command] Babel enable on specified interface or matched network. */
+DEFUN (no_babel_network,
+       no_babel_network_cmd,
+       "no network IF_OR_ADDR",
+       NO_STR
+       "Babel enable on specified interface or network.\n"
+       "Interface or address")
+{
+    int ret;
+    struct prefix p;
+
+    ret = str2prefix (argv[0], &p);
+
+    /* Given string is:               */
+    if (ret) /* an IPv4 or v6 network */
+        return CMD_ERR_NO_MATCH; /* not implemented yet */
+    else     /* an interface name     */
+        ret = babel_enable_if_delete (argv[0]);
+
+    if (ret < 0) {
+        vty_out (vty, "can't find network %s%s", argv[0],
+                 VTY_NEWLINE);
+        return CMD_WARNING;
+    }
+
+    return CMD_SUCCESS;
+}
+
+/* [Interface Command] Tell the interface is wire. */
+DEFUN (babel_set_wired,
+       babel_set_wired_cmd,
+       "wired",
+       "Set this interface as wired (default: wireless).\n"
+       "No attributes")
+{
+    struct interface *ifp;
+    babel_interface_nfo *babel_ifp;
+
+    ifp = vty->index;
+    babel_ifp = babel_get_if_nfo(ifp);
+
+    assert (babel_ifp != NULL);
+    babel_ifp->flags |= BABEL_IF_WIRED;
+    return CMD_SUCCESS;
+}
+
+/* [Interface Command] Tell the interface is wireless (default). */
+DEFUN (babel_set_wireless,
+       babel_set_wireless_cmd,
+       "wireless",
+       NO_STR
+       "Set this interface as wireless (is default).\n"
+       "No attributes")
+{
+    struct interface *ifp;
+    babel_interface_nfo *babel_ifp;
+
+    ifp = vty->index;
+    babel_ifp = babel_get_if_nfo(ifp);
+
+    assert (babel_ifp != NULL);
+    babel_ifp->flags &= ~BABEL_IF_WIRED;
+    return CMD_SUCCESS;
+}
+
+/* [Interface Command] Enable split horizon. */
+DEFUN (babel_split_horizon,
+       babel_split_horizon_cmd,
+       "babel split-horizon",
+       IPV6_STR
+       "Routing Information Protocol\n"
+       "Perform split horizon\n")
+{
+    struct interface *ifp;
+    babel_interface_nfo *babel_ifp;
+
+    ifp = vty->index;
+    babel_ifp = babel_get_if_nfo(ifp);
+
+    assert (babel_ifp != NULL);
+    babel_ifp->flags |= BABEL_IF_SPLIT_HORIZON;
+    return CMD_SUCCESS;
+}
+
+/* [Interface Command] Disable split horizon (default). */
+DEFUN (no_babel_split_horizon,
+       no_babel_split_horizon_cmd,
+       "no babel split-horizon",
+       NO_STR
+       IPV6_STR
+       "Routing Information Protocol\n"
+       "Perform split horizon\n")
+{
+    struct interface *ifp;
+    babel_interface_nfo *babel_ifp;
+
+    ifp = vty->index;
+    babel_ifp = babel_get_if_nfo(ifp);
+
+    assert (babel_ifp != NULL);
+    babel_ifp->flags &= ~BABEL_IF_SPLIT_HORIZON;
+    return CMD_SUCCESS;
+}
+
+/* [Interface Command]. */
+DEFUN (babel_set_hello_interval,
+       babel_set_hello_interval_cmd,
+       "hello interval <5-1000000>",
+       "Set interface's hello interval (default: 4000).\n"
+       "Value in miliseconds\n")
+{
+    struct interface *ifp;
+    babel_interface_nfo *babel_ifp;
+
+    int interval = atoi(argv[1]);
+
+    ifp = vty->index;
+    babel_ifp = babel_get_if_nfo(ifp);
+
+    assert (babel_ifp != NULL);
+    babel_ifp->hello_interval = interval;
+    return CMD_SUCCESS;
+}
+
+/* [Interface Command]. */
+DEFUN (babel_passive_interface,
+       babel_passive_interface_cmd,
+       "passive-interface",
+       "The daemon will only announce redistributed routes\n"
+       "Interface name\n")
+{
+    if (allow_duplicates) {
+        return CMD_WARNING;
+    }
+    parasitic = -1;
+    return CMD_SUCCESS;
+}
+
+/* [Interface Command]. */
+DEFUN (no_babel_passive_interface,
+       no_babel_passive_interface_cmd,
+       "no passive-interface",
+       NO_STR
+       "The daemon will announce all (filtred) routes\n"
+       "Interface name\n")
+{
+    parasitic = 0;
+    return CMD_SUCCESS;
+}
+
+
+int
+interface_idle(babel_interface_nfo *babel_ifp)
+{
+    return (idle_hello_interval > 0 &&
+            babel_ifp->activity_time < babel_now.tv_sec - idle_time);
+}
+
+/* This should be no more than half the hello interval, so that hellos
+   aren't sent late.  The result is in milliseconds. */
+unsigned
+jitter(babel_interface_nfo *babel_ifp, int urgent)
+{
+    unsigned interval = babel_ifp->hello_interval;
+    if(urgent)
+        interval = MIN(interval, 100);
+    else
+        interval = MIN(interval, 4000);
+    return roughly(interval) / 4;
+}
+
+unsigned
+update_jitter(babel_interface_nfo *babel_ifp, int urgent)
+{
+    unsigned interval = babel_ifp->hello_interval;
+    if(urgent)
+        interval = MIN(interval, 100);
+    else
+        interval = MIN(interval, 4000);
+    return roughly(interval);
+}
+
+/* calculate babeld's specific datas of an interface (change when the interface
+ change) */
+static int
+interface_recalculate(struct interface *ifp)
+{
+    babel_interface_nfo *babel_ifp = babel_get_if_nfo(ifp);
+    unsigned char *tmp = NULL;
+    int mtu, rc;
+    struct ipv6_mreq mreq;
+
+    mtu = MIN(ifp->mtu, ifp->mtu6);
+
+    /* We need to be able to fit at least two messages into a packet,
+     so MTUs below 116 require lower layer fragmentation. */
+    /* In IPv6, the minimum MTU is 1280, and every host must be able
+     to reassemble up to 1500 bytes, but I'd rather not rely on this. */
+    if(mtu < 128) {
+        debugf(BABEL_DEBUG_IF, "Suspiciously low MTU %d on interface %s (%d).",
+               mtu, ifp->name, ifp->ifindex);
+        mtu = 128;
+    }
+
+    /* 40 for IPv6 header, 8 for UDP header, 12 for good luck. */
+    babel_ifp->bufsize = mtu - sizeof(packet_header) - 60;
+    tmp = babel_ifp->sendbuf;
+    babel_ifp->sendbuf = realloc(babel_ifp->sendbuf, babel_ifp->bufsize);
+    if(babel_ifp->sendbuf == NULL) {
+        fprintf(stderr, "Couldn't reallocate sendbuf.\n");
+        free(tmp);
+        babel_ifp->bufsize = 0;
+        return -1;
+    }
+    tmp = NULL;
+
+    resize_receive_buffer(mtu);
+
+    if(!(babel_ifp->flags & BABEL_IF_WIRED)) { /* if (wired) */
+        babel_ifp->cost = 96;
+        babel_ifp->flags &= ~BABEL_IF_LQ;
+    } else {
+        babel_ifp->cost = 256;
+        babel_ifp->flags |= BABEL_IF_LQ;
+    }
+
+    babel_ifp->activity_time = babel_now.tv_sec;
+    /* Since the interface was marked as active above, the
+     idle_hello_interval cannot be the one being used here. */
+    babel_ifp->update_interval = babel_ifp->hello_interval * 4;
+
+    memset(&mreq, 0, sizeof(mreq));
+    memcpy(&mreq.ipv6mr_multiaddr, protocol_group, 16);
+    mreq.ipv6mr_interface = ifp->ifindex;
+
+    rc = setsockopt(protocol_socket, IPPROTO_IPV6, IPV6_JOIN_GROUP,
+                    (char*)&mreq, sizeof(mreq));
+    if(rc < 0) {
+        zlog_err("setsockopt(IPV6_JOIN_GROUP) on interface '%s': %s",
+                 ifp->name, safe_strerror(errno));
+        /* This is probably due to a missing link-local address,
+         so down this interface, and wait until the main loop
+         tries to up it again. */
+        interface_reset(ifp);
+        return -1;
+    }
+
+    set_timeout(&babel_ifp->hello_timeout, babel_ifp->hello_interval);
+    set_timeout(&babel_ifp->update_timeout, babel_ifp->update_interval);
+    send_hello(ifp);
+    send_request(ifp, NULL, 0);
+
+    update_interface_metric(ifp);
+
+    debugf(BABEL_DEBUG_COMMON,
+           "Upped network %s (%s, cost=%d%s).",
+           ifp->name,
+           (babel_ifp->flags & BABEL_IF_WIRED) ? "wired" : "wireless",
+           babel_ifp->cost,
+           babel_ifp->ipv4 ? ", IPv4" : "");
+
+    if(rc > 0)
+        send_update(ifp, 0, NULL, 0);
+
+    /* Check and set if interface is enable. */
+    if (babel_enable_if_lookup(ifp->name) >= 0) {
+        babel_ifp->flags |= BABEL_IF_IS_ENABLE;
+    } else {
+        babel_ifp->flags &= ~BABEL_IF_IS_ENABLE;
+    }
+
+    return 1;
+}
+
+/* Reset the interface as it was new: it's not removed from the interface list,
+ and may be considered as a upped interface. */
+static int
+interface_reset(struct interface *ifp)
+{
+    int rc;
+    struct ipv6_mreq mreq;
+    babel_interface_nfo *babel_ifp = babel_get_if_nfo(ifp);
+
+    flush_interface_routes(ifp, 0);
+    babel_ifp->buffered = 0;
+    babel_ifp->bufsize = 0;
+    free(babel_ifp->sendbuf);
+    babel_ifp->num_buffered_updates = 0;
+    babel_ifp->update_bufsize = 0;
+    if(babel_ifp->buffered_updates)
+        free(babel_ifp->buffered_updates);
+    babel_ifp->buffered_updates = NULL;
+    babel_ifp->sendbuf = NULL;
+
+    if(ifp->ifindex > 0) {
+        memset(&mreq, 0, sizeof(mreq));
+        memcpy(&mreq.ipv6mr_multiaddr, protocol_group, 16);
+        mreq.ipv6mr_interface = ifp->ifindex;
+        rc = setsockopt(protocol_socket, IPPROTO_IPV6, IPV6_LEAVE_GROUP,
+                        (char*)&mreq, sizeof(mreq));
+        if(rc < 0)
+            zlog_err("setsockopt(IPV6_LEAVE_GROUP) on interface '%s': %s",
+                     ifp->name, safe_strerror(errno));
+    }
+
+    update_interface_metric(ifp);
+
+    debugf(BABEL_DEBUG_COMMON,"Upped network %s (%s, cost=%d%s).",
+           ifp->name,
+           (babel_ifp->flags & BABEL_IF_WIRED) ? "wired" : "wireless",
+           babel_ifp->cost,
+           babel_ifp->ipv4 ? ", IPv4" : "");
+
+    return 1;
+}
+
+/* Send retraction to all, and reset all interfaces statistics. */
+void
+babel_interface_close_all(void)
+{
+    struct interface *ifp = NULL;
+    struct listnode *linklist_node = NULL;
+
+    FOR_ALL_INTERFACES(ifp, linklist_node) {
+        if(!if_up(ifp))
+            continue;
+        send_wildcard_retraction(ifp);
+        /* Make sure that we expire quickly from our neighbours'
+         association caches. */
+        send_hello_noupdate(ifp, 10);
+        flushbuf(ifp);
+        usleep(roughly(1000));
+        gettime(&babel_now);
+    }
+    FOR_ALL_INTERFACES(ifp, linklist_node) {
+        if(!if_up(ifp))
+            continue;
+        /* Make sure they got it. */
+        send_wildcard_retraction(ifp);
+        send_hello_noupdate(ifp, 1);
+        flushbuf(ifp);
+        usleep(roughly(10000));
+        gettime(&babel_now);
+        interface_reset(ifp);
+    }
+}
+
+/* return "true" if address is one of our ipv6 addresses */
+int
+is_interface_ll_address(struct interface *ifp, const unsigned char *address)
+{
+    struct connected *connected;
+    struct listnode *node;
+
+    if(!if_up(ifp))
+        return 0;
+
+    FOR_ALL_INTERFACES_ADDRESSES(ifp, connected, node) {
+        if(connected->address->family == AF_INET6 &&
+           memcmp(&connected->address->u.prefix6, address, 16) == 0)
+            return 1;
+    }
+
+    return 0;
+}
+
+
+void
+babel_if_init ()
+{
+    /* initialize interface list */
+    if_init();
+    if_add_hook (IF_NEW_HOOK,    babel_if_new_hook);
+    if_add_hook (IF_DELETE_HOOK, babel_if_delete_hook);
+
+    babel_enable_if = vector_init (1);
+
+    /* install interface node and commands */
+    install_element (CONFIG_NODE, &interface_cmd);
+    install_element (CONFIG_NODE, &no_interface_cmd);
+    install_node (&babel_interface_node, interface_config_write);
+    install_default(INTERFACE_NODE);
+    install_element(INTERFACE_NODE, &interface_cmd);
+    install_element(INTERFACE_NODE, &no_interface_cmd);
+
+    install_element(BABEL_NODE, &babel_network_cmd);
+    install_element(BABEL_NODE, &no_babel_network_cmd);
+    install_element(INTERFACE_NODE, &babel_split_horizon_cmd);
+    install_element(INTERFACE_NODE, &no_babel_split_horizon_cmd);
+    install_element(INTERFACE_NODE, &babel_set_wired_cmd);
+    install_element(INTERFACE_NODE, &babel_set_wireless_cmd);
+    install_element(INTERFACE_NODE, &babel_set_hello_interval_cmd);
+    install_element(INTERFACE_NODE, &babel_passive_interface_cmd);
+    install_element(INTERFACE_NODE, &no_babel_passive_interface_cmd);
+}
+
+/* hooks: functions called respectively when struct interface is
+ created or deleted. */
+static int
+babel_if_new_hook (struct interface *ifp)
+{
+    ifp->info = babel_interface_allocate();
+    return 0;
+}
+
+static int
+babel_if_delete_hook (struct interface *ifp)
+{
+    babel_interface_free(ifp->info);
+    ifp->info = NULL;
+    return 0;
+}
+
+/* Configuration write function for babeld. */
+static int
+interface_config_write (struct vty *vty)
+{
+    struct listnode *node;
+    struct interface *ifp;
+    babel_interface_nfo *babel_ifp;
+    int write = 0;
+
+    for (ALL_LIST_ELEMENTS_RO (iflist, node, ifp)) {
+        babel_ifp = babel_get_if_nfo(ifp);
+
+        /* Do not display the interface if there is no configuration about it */
+        if (ifp->desc == NULL)
+            continue;
+
+        vty_out (vty, "interface %s%s", ifp->name,
+                 VTY_NEWLINE);
+        if (ifp->desc)
+            vty_out (vty, " description %s%s", ifp->desc,
+                     VTY_NEWLINE);
+
+        /* TODO: to be completed... */
+
+        vty_out (vty, "!%s", VTY_NEWLINE);
+
+        write++;
+    }
+    return write;
+}
+
+/* functions to allocate or free memory for a babel_interface_nfo, filling
+ needed fields */
+static babel_interface_nfo *
+babel_interface_allocate ()
+{
+    babel_interface_nfo *babel_ifp;
+    babel_ifp = XMALLOC(MTYPE_BABEL_IF, sizeof(babel_interface_nfo));
+    if(babel_ifp == NULL)
+        return NULL;
+
+    /* Here are set the default values for an interface. */
+    memset(babel_ifp, 0, sizeof(babel_interface_nfo));
+    /* All flags are unset */
+    babel_ifp->activity_time = babel_now.tv_sec;
+    babel_ifp->bucket_time = babel_now.tv_sec;
+    babel_ifp->bucket = BUCKET_TOKENS_MAX;
+    babel_ifp->hello_seqno = (random() & 0xFFFF);
+    babel_ifp->hello_interval = BABELD_DEFAULT_HELLO_INTERVAL;
+
+    return babel_ifp;
+}
+
+static void
+babel_interface_free (babel_interface_nfo *babel_ifp)
+{
+    XFREE(MTYPE_BABEL_IF, babel_ifp);
+}