addrmgr: skip never-successful addresses

A node that has never been successfully connected should not be
announced.  Also, change maxFailures from 10 to a more conservative 5.

addrmgr/addrmanager.go

@@ -143,14 +143,14 @@ const (
 
 	// maxFailures is the maximum number of failures we will accept without
 	// a success before considering an address bad.
-	maxFailures = 10
+	maxFailures = 5
 
 	// minBadDays is the number of days since the last success before we
 	// will consider evicting an address.
 	minBadDays = 7
 
 	// getAddrMax is the most addresses that we will send in response
-	// to a getAddr (in practise the most addresses we will return from a
+	// to a getAddr (in practice the most addresses we will return from a
 	// call to AddressCache()).
 	getAddrMax = 2500
 
@@ -668,6 +668,10 @@ func (a *AddrManager) AddressCache() []*wire.NetAddress {
 		if v.isBad() {
 			continue
 		}
+		// Skip addresses that never succeeded.
+		if v.lastsuccess.IsZero() {
+			continue
+		}
 		allAddr = append(allAddr, v.na)
 	}
 

addrmgr/knownaddress.go

@@ -73,7 +73,7 @@ func (ka *KnownAddress) chance() float64 {
 // 1) It claims to be from the future
 // 2) It hasn't been seen in over a month
 // 3) It has failed at least three times and never succeeded
-// 4) It has failed ten times in the last week
+// 4) It has failed a total of maxFailures in the last week
 // All addresses that meet these criteria are assumed to be worthless and not
 // worth keeping hold of.
 func (ka *KnownAddress) isBad() bool {