Avoid hanging the caller when we try to claim from a dead peer

ipam/claim.go

@@ -45,7 +45,11 @@ func (c *claim) Try(alloc *Allocator) bool {
 		return false
 	default:
 		alloc.debugf("requesting address %s from other peer %s", c.addr, owner)
-		alloc.sendSpaceRequest(owner, address.NewRange(c.addr, 1))
+		err := alloc.sendSpaceRequest(owner, address.NewRange(c.addr, 1))
+		if err != nil { // can't speak to owner right now; figure it out later
+			alloc.infof("Claim %s for %s: %s; will try later.", c.addr, c.ident, err)
+			c.sendResult(nil)
+		}
 		return false
 	}
 

test/160_claim_test.sh

@@ -27,4 +27,14 @@ assert_raises "[ $C3 != $C1 ]"
 
 assert_raises "exec_on $HOST1 c1 $PING $C3"
 
+stop_router_on $HOST1
+stop_router_on $HOST2
+
+# Now make host1 attempt to claim from host2, when host2 is stopped
+weave_on $HOST2 launch-router
+# Introduce host3 to remember the IPAM CRDT when we stop host2
+weave_on $HOST3 launch-router $HOST2
+stop_router_on $HOST2
+weave_on $HOST1 launch-router --log-level=debug $HOST3
+
 end_suite