Send a RTM_PROPOSAL to clear out other dhclient instances on startup.

Replaces forcing interface link state down and up to generate
RTM_IFINFO messages.

diff --git a/sbin/dhclient/dhclient.c b/sbin/dhclient/dhclient.c
index 89bf3b5..13f3467 100644 (file)
--- a/sbin/dhclient/dhclient.c
+++ b/sbin/dhclient/dhclient.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: dhclient.c,v 1.406 2017/04/04 13:01:20 krw Exp $      */
+/*     $OpenBSD: dhclient.c,v 1.407 2017/04/04 15:15:48 krw Exp $      */
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -169,6 +169,7 @@ struct client_lease *packet_to_lease(struct interface_info *, struct in_addr,
     struct option_data *);
 void go_daemon(void);
 int rdaemon(int);
+void   take_charge(struct interface_info *);
 
 #define        ROUNDUP(a) \
            ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
@@ -261,6 +262,22 @@ routehandler(struct interface_info *ifi)
                goto done;
 
        switch (rtm->rtm_type) {
+       case RTM_PROPOSAL:
+               if (rtm->rtm_index != ifi->index ||
+                   rtm->rtm_priority != RTP_PROPOSAL_DHCLIENT)
+                       goto done;
+               if ((rtm->rtm_flags & RTF_PROTO3) != 0) {
+                       if (rtm->rtm_seq == client->xid) {
+                               client->flags |= IN_CHARGE;
+                               goto done;
+                       } else if ((client->flags & IN_CHARGE) != 0) {
+                               rslt = asprintf(&errmsg, "yielding "
+                                   "responsibility for %s",
+                                   ifi->name);
+                               goto die;
+                       }
+               }
+               break;
        case RTM_NEWADDR:
                ifam = (struct ifa_msghdr *)rtm;
                if (ifam->ifam_index != ifi->index)
@@ -641,8 +658,9 @@ main(int argc, char *argv[])
        if ((routefd = socket(PF_ROUTE, SOCK_RAW, 0)) == -1)
                fatal("socket(PF_ROUTE, SOCK_RAW)");
 
-       rtfilter = ROUTE_FILTER(RTM_NEWADDR) | ROUTE_FILTER(RTM_DELADDR) |
-           ROUTE_FILTER(RTM_IFINFO) | ROUTE_FILTER(RTM_IFANNOUNCE);
+       rtfilter = ROUTE_FILTER(RTM_PROPOSAL) | ROUTE_FILTER(RTM_NEWADDR) |
+           ROUTE_FILTER(RTM_DELADDR) | ROUTE_FILTER(RTM_IFINFO) |
+           ROUTE_FILTER(RTM_IFANNOUNCE);
 
        if (setsockopt(routefd, PF_ROUTE, ROUTE_MSGFILTER,
            &rtfilter, sizeof(rtfilter)) == -1)
@@ -651,6 +669,8 @@ main(int argc, char *argv[])
            sizeof(ifi->rdomain)) == -1)
                fatal("setsockopt(ROUTE_TABLEFILTER)");
 
+       take_charge(ifi);
+
        /* Register the interface. */
        if_register_receive(ifi);
        if_register_send(ifi);
@@ -2958,3 +2978,58 @@ compare_lease(struct client_lease *active, struct client_lease *new)
 
        return (0);
 }
+
+void
+take_charge(struct interface_info *ifi)
+{
+       struct  pollfd fds[1];
+       struct  rt_msghdr rtm;
+       time_t  start_time, cur_time;
+       int     retries;
+
+       if (time(&start_time) == -1)
+               fatal("time");
+
+       /*
+        * Send RTM_PROPOSAL with RTF_PROTO3 set.
+        *
+        * When it comes back, we're in charge and other dhclients are
+        * dead processes walking.
+        */
+       memset(&rtm, 0, sizeof(rtm));
+
+       rtm.rtm_version = RTM_VERSION;
+       rtm.rtm_type = RTM_PROPOSAL;
+       rtm.rtm_msglen = sizeof(rtm);
+       rtm.rtm_tableid = ifi->rdomain;
+       rtm.rtm_index = ifi->index;
+       rtm.rtm_seq = ifi->client->xid = arc4random();
+       rtm.rtm_priority = RTP_PROPOSAL_DHCLIENT;
+       rtm.rtm_addrs = 0;
+       rtm.rtm_flags = RTF_UP | RTF_PROTO3;
+
+       retries = 0;
+       while ((ifi->client->flags & IN_CHARGE) == 0) {
+               if (write(routefd, &rtm, sizeof(rtm)) == -1)
+                       fatal("tried to take charge");
+               time(&cur_time);
+               if ((cur_time - start_time) > 3) {
+                       if (++retries <= 3) {
+                               if (time(&start_time) == -1)
+                                       fatal("time");
+                       } else {
+                               fatalx("failed to take charge of %s",
+                                   ifi->name);
+                       }
+               }
+               fds[0].fd = routefd;
+               fds[0].events = POLLIN;
+               if (poll(fds, 1, 3) == -1) {
+                       if (errno == EAGAIN || errno == EINTR)
+                               continue;
+                       fatal("routefd poll");
+               }
+               if ((fds[0].revents & (POLLIN | POLLHUP)))
+                       routehandler(ifi);
+       }
+}

diff --git a/sbin/dhclient/dhcpd.h b/sbin/dhclient/dhcpd.h
index f599a6d..1aae45d 100644 (file)
--- a/sbin/dhclient/dhcpd.h
+++ b/sbin/dhclient/dhcpd.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: dhcpd.h,v 1.163 2017/04/04 13:01:20 krw Exp $ */
+/*     $OpenBSD: dhcpd.h,v 1.164 2017/04/04 15:15:48 krw Exp $ */
 
 /*
  * Copyright (c) 2004 Henning Brauer <henning@openbsd.org>
@@ -131,6 +131,7 @@ struct client_state {
        struct in_addr           destination;
        int                      flags;
 #define IS_RESPONSIBLE 0x1
+#define IN_CHARGE      0x2
        u_int32_t                xid;
        u_int16_t                secs;
        time_t                   first_sending;

diff --git a/sbin/dhclient/dispatch.c b/sbin/dhclient/dispatch.c
index dfab902..2165c0f 100644 (file)
--- a/sbin/dhclient/dispatch.c
+++ b/sbin/dhclient/dispatch.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: dispatch.c,v 1.117 2017/03/08 15:46:36 krw Exp $      */
+/*     $OpenBSD: dispatch.c,v 1.118 2017/04/04 15:15:48 krw Exp $      */
 
 /*
  * Copyright 2004 Henning Brauer <henning@openbsd.org>
@@ -233,21 +233,17 @@ interface_link_forceup(char *ifname)
        memset(&ifr, 0, sizeof(ifr));
        strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
        if (ioctl(sock, SIOCGIFFLAGS, (caddr_t)&ifr) == -1) {
-               log_warn("interface_link_forceup: SIOCGIFFLAGS failed");
+               log_warn("SIOCGIFFLAGS");
                return;
        }
 
-       /* Force it down and up so others notice link state change. */
-       ifr.ifr_flags &= ~IFF_UP;
-       if (ioctl(sock, SIOCSIFFLAGS, (caddr_t)&ifr) == -1) {
-               log_warn("interface_link_forceup: SIOCSIFFLAGS DOWN failed");
-               return;
-       }
-
-       ifr.ifr_flags |= IFF_UP;
-       if (ioctl(sock, SIOCSIFFLAGS, (caddr_t)&ifr) == -1) {
-               log_warn("interface_link_forceup: SIOCSIFFLAGS UP failed");
-               return;
+       /* Force it up if it isn't already. */
+       if ((ifr.ifr_flags & IFF_UP) == 0) {
+               ifr.ifr_flags |= IFF_UP;
+               if (ioctl(sock, SIOCSIFFLAGS, (caddr_t)&ifr) == -1) {
+                       log_warn("SIOCSIFFLAGS");
+                       return;
+               }
        }
 }