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/*
* Interface autoconfiguration functions for netcfg.
*
* This program is free software; you can redistribute it 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 program 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, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "netcfg.h"
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <ifaddrs.h>
#include <net/if.h>
#include <debian-installer.h>
#define DHCP6C_PIDFILE "/var/run/dhcp6c.pid"
#define DHCP6C_FINISHED "/var/lib/netcfg/dhcp6c-finished"
static enum { DHCLIENT, DHCP6C } dhcpv6_client;
static int dhcpv6_pipe[2] = { -1, -1 };
static pid_t dhcpv6_pid = -1;
static int dhcpv6_exit_status = 1;
/* Signal handler for DHCPv6 client child
*
* When the child exits (either because it failed to obtain a
* lease or because it succeeded and daemonized itself), this
* gets the child's exit status and sets dhcpv6_pid to -1
*/
void cleanup_dhcpv6_client(void)
{
if (dhcpv6_pid <= 0)
/* Already cleaned up */
return;
if (waitpid(dhcpv6_pid, &dhcpv6_exit_status, WNOHANG) != dhcpv6_pid)
/* Wasn't us */
return;
if (WIFEXITED(dhcpv6_exit_status) || WIFSIGNALED(dhcpv6_exit_status))
dhcpv6_pid = -1;
}
/* Start whichever DHCPv6 client is available.
*
* The client's PID is stored in dhcpv6_pid.
*/
int start_dhcpv6_client(struct debconfclient *client, const struct netcfg_interface *interface)
{
if (access("/sbin/dhclient", F_OK) == 0)
dhcpv6_client = DHCLIENT;
else if (access("/usr/sbin/dhcp6c", F_OK) == 0)
dhcpv6_client = DHCP6C;
else {
/* for now, fall back quietly (no debconf error) to IPv4 */
di_error("No DHCPv6 client found");
return 1;
}
if (pipe(dhcpv6_pipe) < 0) {
di_error("Unable to create pipe: %s", strerror(errno));
return 1;
}
if (dhcpv6_client == DHCP6C) {
unlink(DHCP6C_FINISHED);
if (!interface->v6_stateless_config) {
/* So that poll_dhcpv6_client won't immediately give
* up:
*/
FILE *pidfile = fopen(DHCP6C_PIDFILE, "w");
if (pidfile)
fclose(pidfile);
}
}
dhcpv6_pid = fork();
if (dhcpv6_pid == 0) { /* child */
FILE *dc;
const char **arguments;
int i = 0;
/* disassociate from debconf */
fclose(client->out);
close(dhcpv6_pipe[0]);
dup2(dhcpv6_pipe[1], 1);
close(dhcpv6_pipe[1]);
switch (dhcpv6_client) {
case DHCLIENT:
dc = file_open(DHCLIENT6_FILE, "w");
if (!dc)
return 1;
fprintf(dc, "send vendor-class-identifier \"d-i\";\n");
fclose(dc);
arguments = malloc(9 * sizeof(*arguments));
i = 0;
arguments[i++] = "dhclient";
arguments[i++] = "-6";
if (interface->v6_stateless_config)
arguments[i++] = "-S";
arguments[i++] = "-cf";
arguments[i++] = DHCLIENT6_FILE;
arguments[i++] = "-sf";
arguments[i++] = "/lib/netcfg/print-dhcpv6-info";
arguments[i++] = interface->name;
arguments[i] = NULL;
execvp("dhclient", (char **)arguments);
break;
case DHCP6C:
if (!interface->v6_stateless_config) {
/* In stateful mode, dhcp6c needs to stay
* running. However, it daemonises itself
* in such a way as to throw away stdio,
* which interferes with our script
* communication. To work around this,
* daemonise here without throwing away
* stdio and then run dhcp6c in foreground
* mode.
*/
if (daemon(0, 1) < 0) {
di_error("daemon() failed: %s", strerror(errno));
_exit(1);
}
}
dc = file_open(DHCP6C_FILE, "w");
if (!dc)
return 1;
fprintf(dc, "interface %s {\n", interface->name);
if (interface->v6_stateless_config)
fprintf(dc, "\tinformation-only;\n");
else
fprintf(dc, "\tsend ia-na 0;\n");
fprintf(dc, "\trequest domain-name-servers;\n");
fprintf(dc, "\trequest domain-name;\n");
fprintf(dc, "\tscript \"/lib/netcfg/print-dhcp6c-info\";\n");
fprintf(dc, "};\n");
if (!interface->v6_stateless_config) {
fprintf(dc, "id-assoc na 0 {\n");
fprintf(dc, "};\n");
}
fclose(dc);
arguments = malloc(6 * sizeof(*arguments));
arguments[i++] = "dhcp6c";
arguments[i++] = "-c";
arguments[i++] = DHCP6C_FILE;
arguments[i++] = "-f";
arguments[i++] = interface->name;
arguments[i] = NULL;
execvp("dhcp6c", (char **)arguments);
break;
}
if (errno)
di_error("Could not exec DHCPv6 client: %s", strerror(errno));
_exit(1); /* should never be reached */
} else if (dhcpv6_pid == -1) {
di_warning("DHCPv6 fork failed; this is unlikely to end well");
close(dhcpv6_pipe[0]);
close(dhcpv6_pipe[1]);
dhcpv6_pipe[0] = dhcpv6_pipe[1] = -1;
return 1;
} else { /* parent */
di_warning("Started DHCPv6 client; PID is %i", dhcpv6_pid);
close(dhcpv6_pipe[1]);
dhcpv6_pipe[1] = -1;
signal(SIGCHLD, &sigchld_handler);
return 0;
}
}
/* Poll the started DHCP client for netcfg/dhcpv6_timeout seconds (def. 15)
* and return true if a lease is known to have been acquired, 0 otherwise.
*
* The client should be run such that it exits once a lease is acquired
* (although its child continues to run as a daemon). Unfortunately, dhcp6c
* can only daemonise immediately rather than waiting for a lease, so we
* have to handle this for the stateful case.
*
* This function will NOT kill the child if time runs out. This allows
* the user to choose to wait longer for the lease to be acquired.
*/
static int poll_dhcpv6_client (struct debconfclient *client, const struct netcfg_interface *interface)
{
int seconds_slept = 0;
int dhcpv6_seconds;
int got_lease = -1;
int ret = 0;
debconf_get(client, "netcfg/dhcpv6_timeout");
dhcpv6_seconds = atoi(client->value);
/* show progress bar */
debconf_capb(client, "backup progresscancel");
debconf_progress_start(client, 0, dhcpv6_seconds, "netcfg/dhcpv6_progress");
if (debconf_progress_info(client, "netcfg/dhcp_progress_note") == 30)
goto stop;
for (;;) {
struct stat st;
switch (dhcpv6_client) {
case DHCLIENT:
if (dhcpv6_pid <= 0)
got_lease = (dhcpv6_exit_status == 0);
break;
case DHCP6C:
if (dhcpv6_pid <= 0 && dhcpv6_exit_status != 0) {
got_lease = 0;
break;
}
if (!interface->v6_stateless_config &&
dhcpv6_pid <= 0) {
/* In stateful mode, we run dhcp6c as a
* daemon (because it doesn't wait for a
* lease before daemonising anyway, and this
* lets us set up its file descriptors
* properly), so dhcpv6_pid will exit fairly
* quickly. We can check its pid file to
* find out whether it's really exited, in
* which case we'll have lost the lease.
*/
if (stat(DHCP6C_PIDFILE, &st) < 0) {
got_lease = 0;
break;
}
}
/* We write a sentinel file at the end of
* print-dhcp6c-info, which is a solid indication
* that we got useful configuration.
*/
if (stat(DHCP6C_FINISHED, &st) == 0) {
got_lease = 1;
break;
}
break;
}
if (got_lease != -1 || seconds_slept++ >= dhcpv6_seconds)
break;
sleep(1);
if (debconf_progress_step(client, 1) == 30)
goto stop;
}
if (got_lease == 1) {
ret = 1;
debconf_capb(client, "backup"); /* stop displaying cancel button */
if (debconf_progress_set(client, dhcpv6_seconds) == 30)
goto stop;
if (debconf_progress_info(client, "netcfg/dhcp_success_note") == 30)
goto stop;
sleep(1);
}
stop:
/* stop progress bar */
debconf_progress_stop(client);
debconf_capb(client, "backup");
/* terminate dhcp6c if there's no lease or information yet */
if (dhcpv6_client == DHCP6C && (got_lease != 1 || dhcpv6_pid > 0)) {
FILE *pidfile = fopen(DHCP6C_PIDFILE, "r");
if (pidfile) {
char *line = NULL;
size_t dummy;
if (getline(&line, &dummy, pidfile) >= 0) {
pid_t pid;
errno = 0;
pid = strtol(line, NULL, 10);
if (errno == 0)
kill(pid, SIGTERM);
}
free(line);
fclose(pidfile);
}
}
if (dhcpv6_client == DHCP6C)
unlink(DHCP6C_FINISHED);
return ret;
}
/* Configure the interface using DHCPv6. */
static int netcfg_dhcpv6(struct debconfclient *client, struct netcfg_interface *interface)
{
FILE *dhcpv6_reader = NULL;
char l[512], *p;
int ns_idx, ntp_idx = 0;
int rv;
if (interface->v6_stateless_config)
di_debug("Stateless DHCPv6 requested");
else
di_debug("Stateful DHCPv6 requested");
/* Append any nameservers obtained via DHCP to the list of
* nameservers in the RA, rather than overwriting them
*/
ns_idx = nameserver_count(interface);
if (start_dhcpv6_client(client, interface)) {
di_warning("DHCPv6 client failed to start. Aborting DHCPv6 configuration.");
return 0;
}
rv = poll_dhcpv6_client(client, interface);
dhcpv6_reader = fdopen(dhcpv6_pipe[0], "r");
while (fgets(l, sizeof(l), dhcpv6_reader) != NULL) {
rtrim(l);
di_debug("DHCPv6 line: %s", l);
if (!strncmp("nameserver[", l, 11) && ns_idx < NETCFG_NAMESERVERS_MAX) {
p = strstr(l, "] ") + 2;
strncpy(interface->nameservers[ns_idx], p, sizeof(interface->nameservers[ns_idx]));
ns_idx++;
} else if (!strncmp("NTP server[", l, 11) && ntp_idx < NETCFG_NTPSERVERS_MAX) {
p = strstr(l, "] ") + 2;
strncpy(interface->ntp_servers[ntp_idx], p, sizeof(interface->ntp_servers[ntp_idx]));
ntp_idx++;
} else if (!strncmp("Domain search list[0] ", l, 21)) {
p = strstr(l, "] ") + 2;
strncpy(domain, p, sizeof(domain));
/* Strip trailing . */
if (domain[strlen(domain)-1] == '.') {
domain[strlen(domain)-1] = '\0';
}
have_domain = 1;
} else if (!strcmp("end", l)) {
/* The write end of the pipe won't necessarily be
* closed in the stateful case, so this hack lets us
* break out.
*/
break;
}
}
fclose(dhcpv6_reader);
dhcpv6_pipe[0] = -1;
if (dhcpv6_client == DHCP6C &&
interface->v6_stateless_config && dhcpv6_pid > 0)
/* dhcp6c doesn't exit after printing information unless in
* info-req (-i) mode, which is incompatible with supplying
* a configuration; so just kill the client now.
*/
kill(dhcpv6_pid, SIGTERM);
/* Empty any other nameservers/NTP servers that might
* have been left over from a previous config run
*/
for (; ns_idx < NETCFG_NAMESERVERS_MAX; ns_idx++) {
*(interface->nameservers[ns_idx]) = '\0';
}
for (; ntp_idx < NETCFG_NTPSERVERS_MAX; ntp_idx++) {
*(interface->ntp_servers[ntp_idx]) = '\0';
}
return rv;
}
/* Configure the network using IPv6 router advertisements, and possibly
* stateless DHCPv6 announcements (if appropriate). Return 1 if all
* went well, and 0 otherwise.
*/
static int netcfg_slaac(struct debconfclient *client, struct netcfg_interface *interface)
{
const int SLAAC_MAX_WAIT = 5; /* seconds */
int count, rv = 0;
/* STEP 1: Ensure the interface has finished configuring itself */
/* Progress bar... fun! */
debconf_capb(client, "progresscancel");
debconf_progress_start(client, 0, SLAAC_MAX_WAIT * 4, "netcfg/slaac_wait_title");
for (count = 0; count < SLAAC_MAX_WAIT * 4; count++) {
usleep(250000);
if (debconf_progress_step(client, 1) == 30) {
/* User cancel */
rv = 0;
break;
}
if (nc_v6_interface_configured(interface, 0)) {
debconf_progress_set(client, SLAAC_MAX_WAIT * 4);
rv = 1;
break;
}
}
debconf_progress_stop(client);
/* STEP 2: Stateless DHCP? */
if (interface->v6_stateless_config)
netcfg_dhcpv6(client, interface);
return rv;
}
/* This function handles all of the autoconfiguration for the given interface.
*
* Autoconfiguration of an interface in netcfg has grown significantly
* in recent times. From humble beginnings that started with "yeah, just
* fire up udhcpc and see what happens", the scope has expanded to
* include all manner of IPv6 gubbins.
*
* Hence, this function exists to wrap all of that into a single neat
* package. If you want to autoconfigure an interface, just run it through
* this, and if autoconfiguration was successful to at least the point of
* assigning an IP address, we will return a healthy bouncing baby '1' to
* you. Otherwise, we'll give you the bad news with a '0' -- and you'll
* either have to try another interface, or manually configure it.
*
* Note that we only guarantee that you'll have an IP address as a result
* of successful completion. You'll need to check what else has been
* configured (gateway, hostname, etc) and respond to the user appropriately.
* Also, the fields in +interface+ that deal directly with IP address,
* gateway, etc will *not* be populated -- just the flags that talk about
* what sort of autoconfiguration was completed.
*/
int netcfg_autoconfig(struct debconfclient *client, struct netcfg_interface *interface)
{
int ipv6;
di_debug("Want link on %s", interface->name);
netcfg_detect_link(client, interface);
di_debug("Commencing network autoconfiguration on %s", interface->name);
interface->dhcp = interface->slaac = interface->dhcpv6 = 0;
/* We need to start rdnssd before anything else, because it never
* sends it's own ND packets, it just watches for ones already
* on the wire. Thankfully, the use of rdisc6 in
* nc_v6_get_config_flags() will send NDs for us.
*/
start_rdnssd(client);
/* Now we prod the network to see what is available */
ipv6 = nc_v6_get_config_flags(client, interface);
/* And now we cleanup from rdnssd */
if (ipv6) {
read_rdnssd_nameservers(interface);
if (nameserver_count(interface) > 0) {
di_debug("Not queueing rdnssd installation to make sure not to interfere with network-manager");
}
}
stop_rdnssd();
if (ipv6) {
di_debug("IPv6 found");
if (interface->v6_stateful_config == 1) {
di_debug("IPv6 stateful autoconfig requested");
if (netcfg_dhcpv6(client, interface))
interface->dhcpv6 = 1;
} else {
di_debug("IPv6 stateless autoconfig requested");
if (netcfg_slaac(client, interface))
interface->slaac = 1;
}
}
if (ipv6)
di_debug("Trying IPv4 autoconfig as well");
else
/* No RA was received; assuming that IPv6 is not available
* on this network and falling back to IPv4
*/
di_debug("No RA received; attempting IPv4 autoconfig");
if (netcfg_dhcp(client, interface))
interface->dhcp = 1;
return interface->dhcp || interface->slaac || interface->dhcpv6;
}
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