Skip to content

Commit

Permalink
ticket: 6019
Browse files Browse the repository at this point in the history 
status: open

On systems with struct rt_msghdr, open a routing socket and wait for
messages; when they come in, if the types suggest a possibility of
network interface reconfiguration, shut down the KDC's networking and
bring it back up again, rescanning the interfaces in the process.

Leaving the ticket open because it should be improved:
 * It should only close down sockets on addresses we no longer have, and
   bring up sockets only on new addresses.
 * If we have IPV6_PKTINFO support, it should only listen for IPv4
   routing changes.
 * If we also have IP_PKTINFO support, it shouldn't be used at all.
 * If we build a KDC on a system with neither struct rt_msghdr nor
   IP_PKTINFO (do we have any such?), we'll need another solution.

Thanks to Nico Williams for the routing socket suggestion, and Apple
for the initial (signal-driven) reconfiguration code.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@20540 dc483132-0cff-0310-8789-dd5450dbe970
  • Loading branch information
raeburn committed Jul 18, 2008
1 parent 555acbd commit 15dbd37
Show file tree
Hide file tree
Showing 2 changed files with 174 additions and 4 deletions.
5 changes: 5 additions & 0 deletions src/configure.in
View file
Expand Up @@ -611,6 +611,11 @@ AC_CHECK_TYPES([struct cmsghdr, struct in_pktinfo, struct in6_pktinfo], , , [
#include <sys/socket.h>
#include <netinet/in.h>
])
AC_CHECK_TYPES([struct rt_msghdr], , , [
#include <sys/socket.h>
#include <net/if.h>
#include <net/route.h>
])
dnl
dnl stuff for util/profile
dnl
Expand Down
173 changes: 169 additions & 4 deletions src/kdc/network.c
View file
Expand Up @@ -175,7 +175,7 @@ static const char *paddr (struct sockaddr *sa)

/* KDC data. */

enum kdc_conn_type { CONN_UDP, CONN_UDP_PKTINFO, CONN_TCP_LISTENER, CONN_TCP };
enum kdc_conn_type { CONN_UDP, CONN_UDP_PKTINFO, CONN_TCP_LISTENER, CONN_TCP, CONN_ROUTING };

/* Per-connection info. */
struct connection {
Expand Down Expand Up @@ -770,6 +770,127 @@ static void klog_handler(const void *data, size_t len)
}
#endif

static int network_reconfiguration_needed = 0;

#ifdef HAVE_STRUCT_RT_MSGHDR
#include <net/route.h>

static char *rtm_type_name(int type)
{
switch (type) {
case RTM_ADD: return "RTM_ADD";
case RTM_DELETE: return "RTM_DELETE";
case RTM_NEWADDR: return "RTM_NEWADDR";
case RTM_DELADDR: return "RTM_DELADDR";
case RTM_IFINFO: return "RTM_IFINFO";
case RTM_OLDADD: return "RTM_OLDADD";
case RTM_OLDDEL: return "RTM_OLDDEL";
case RTM_RESOLVE: return "RTM_RESOLVE";
#ifdef RTM_NEWMADDR
case RTM_NEWMADDR: return "RTM_NEWMADDR";
case RTM_DELMADDR: return "RTM_DELMADDR";
#endif
case RTM_MISS: return "RTM_MISS";
case RTM_REDIRECT: return "RTM_REDIRECT";
case RTM_LOSING: return "RTM_LOSING";
case RTM_GET: return "RTM_GET";
default: return "?";
}
}

static void process_routing_update(struct connection *conn, const char *prog,
int selflags)
{
static struct {
struct rt_msghdr rtm;
char scratchbuf[1024];
} s;
int n_read;

krb5_klog_syslog(LOG_INFO, "routing socket readable");
while ((n_read = read(conn->fd, &s, sizeof(s))) > 0) {
if (n_read < sizeof(s.rtm)) {
krb5_klog_syslog(LOG_ERR, "short read (%d/%d) from routing socket",
n_read, (int) sizeof(s.rtm));
/* Quick hack to figure out if the interesting
fields are present in a short read. */
#define RS(FIELD) (offsetof(struct rt_msghdr, FIELD) + sizeof(s.rtm.FIELD))
if (n_read < RS(rtm_type) ||
n_read < RS(rtm_version) ||
n_read < RS(rtm_msglen))
return;
}
krb5_klog_syslog(LOG_INFO,
"got routing msg type %d(%s) v%d",
s.rtm.rtm_type, rtm_type_name(s.rtm.rtm_type),
s.rtm.rtm_version);
if (s.rtm.rtm_msglen > sizeof(s)) {
krb5_klog_syslog(LOG_ERR,
"routing message bigger than buffer (%d/%d)",
s.rtm.rtm_msglen, (int) sizeof(s));
/* This will probably start spewing messages. Slow it
down. */
sleep(1);
return;
}
if (s.rtm.rtm_msglen != n_read) {
krb5_klog_syslog(LOG_ERR,
"read %d from routing socket but msglen is %d",
n_read, s.rtm.rtm_msglen);
if (s.rtm.rtm_msglen < sizeof(s.rtm)) {
krb5_klog_syslog(LOG_ERR,
"routing msglen shorter than header??");
return;
}
}
switch (s.rtm.rtm_type) {
case RTM_ADD:
case RTM_DELETE:
case RTM_NEWADDR:
case RTM_DELADDR:
case RTM_IFINFO:
case RTM_OLDADD:
case RTM_OLDDEL:
krb5_klog_syslog(LOG_INFO, "reconfiguration needed");
network_reconfiguration_needed = 1;
break;
case RTM_RESOLVE:
#ifdef RTM_NEWMADDR
case RTM_NEWMADDR:
case RTM_DELMADDR:
#endif
case RTM_MISS:
case RTM_REDIRECT:
case RTM_LOSING:
case RTM_GET:
/* Not interesting. */
krb5_klog_syslog(LOG_DEBUG, "routing msg not interesting");
break;
default:
krb5_klog_syslog(LOG_INFO, "unhandled routing message type, will reconfigure just for the fun of it");
network_reconfiguration_needed = 1;
break;
}
}
}

static void
setup_routing_socket(struct socksetup *data)
{
int sock = socket(PF_ROUTE, SOCK_RAW, 0);
if (sock < 0) {
int e = errno;
krb5_klog_syslog(LOG_INFO, "couldn't set up routing socket: %s",
strerror(e));
} else {
krb5_klog_syslog(LOG_INFO, "routing socket is fd %d", sock);
add_fd(data, sock, CONN_ROUTING, process_routing_update);
setnbio(sock);
FD_SET(sock, &sstate.rfds);
}
}
#endif

/* XXX */
extern int krb5int_debug_sendto_kdc;
extern void (*krb5int_sendtokdc_debug_handler)(const void*, size_t);
Expand Down Expand Up @@ -824,6 +945,9 @@ setup_network(const char *prog)
setup_data.prog = prog;
setup_data.retval = 0;
krb5_klog_syslog (LOG_INFO, "setting up network...");
#ifdef HAVE_STRUCT_RT_MSGHDR
setup_routing_socket(&setup_data);
#endif
/* To do: Use RFC 2292 interface (or follow-on) and IPV6_PKTINFO,
so we might need only one UDP socket; fall back to binding
sockets on each address only if IPV6_PKTINFO isn't
Expand Down Expand Up @@ -1395,6 +1519,20 @@ static void service_conn(struct connection *conn, const char *prog,
conn->service(conn, prog, selflags);
}

/* from sendto_kdc.c */
static int getcurtime(struct timeval *tvp)
{
#ifdef _WIN32
struct _timeb tb;
_ftime(&tb);
tvp->tv_sec = tb.time;
tvp->tv_usec = tb.millitm * 1000;
return 0;
#else
return gettimeofday(tvp, 0) ? errno : 0;
#endif
}

krb5_error_code
listen_and_process(const char *prog)
{
Expand All @@ -1403,7 +1541,7 @@ listen_and_process(const char *prog)
can be rather large. Making this static avoids putting all
that junk on the stack. */
static struct select_state sout;
int i, sret;
int i, sret, netchanged = 0;
krb5_error_code err;

if (conns == (struct connection **) NULL)
Expand All @@ -1414,12 +1552,37 @@ listen_and_process(const char *prog)
krb5_klog_reopen(kdc_context);
signal_requests_hup = 0;
}
sstate.end_time.tv_sec = sstate.end_time.tv_usec = 0;

if (network_reconfiguration_needed) {
krb5_klog_syslog(LOG_INFO, "network reconfiguration needed");
/* It might be tidier to add a timer-callback interface to
the control loop here, but for this one use, it's not a
big deal. */
err = getcurtime(&sstate.end_time);
if (err) {
com_err(prog, err, "while getting the time");
continue;
}
sstate.end_time.tv_sec += 3;
netchanged = 1;
} else
sstate.end_time.tv_sec = sstate.end_time.tv_usec = 0;

err = krb5int_cm_call_select(&sstate, &sout, &sret);
if (err) {
com_err(prog, err, "while selecting for network input(1)");
continue;
}
if (sret == 0 && netchanged) {
network_reconfiguration_needed = 0;
closedown_network(prog);
err = setup_network(prog);
if (err) {
com_err(prog, err, "while reinitializing network");
return err;
}
netchanged = 0;
}
if (sret == -1) {
if (errno != EINTR)
com_err(prog, errno, "while selecting for network input(2)");
Expand Down Expand Up @@ -1451,8 +1614,10 @@ closedown_network(const char *prog)
return KDC5_NONET;

FOREACH_ELT (connections, i, conn) {
if (conn->fd >= 0)
if (conn->fd >= 0) {
krb5_klog_syslog(LOG_INFO, "closing down fd %d", conn->fd);
(void) close(conn->fd);
}
DEL (connections, i);
/* There may also be per-connection data in the tcp structure
(tcp.buffer, tcp.response) that we're not freeing here.
Expand Down

0 comments on commit 15dbd37

Please sign in to comment.