peer+server: add new config option to optionally disable stall detection

In this commit, we add a new config options that allows one to start
`btcd` in an operating mode that disables the stall detection. This can
be useful in simnet/regtest integration tests settings where it's
important that `btcd` holds on to its possibly sole connection to the
only other node in the test harness.

A new config flag has been added to gate this behavior, which is off by
default.

config.go

@@ -135,6 +135,7 @@ type config struct {
 	NoRelayPriority      bool          `long:"norelaypriority" description:"Do not require free or low-fee transactions to have high priority for relaying"`
 	NoWinService         bool          `long:"nowinservice" description:"Do not start as a background service on Windows -- NOTE: This flag only works on the command line, not in the config file"`
 	DisableRPC           bool          `long:"norpc" description:"Disable built-in RPC server -- NOTE: The RPC server is disabled by default if no rpcuser/rpcpass or rpclimituser/rpclimitpass is specified"`
+	DisableStallHandler  bool          `long:"nostalldetect" description:"Disables the stall handler system for each peer, useful in simnet/regtest integration tests frameworks"`
 	DisableTLS           bool          `long:"notls" description:"Disable TLS for the RPC server -- NOTE: This is only allowed if the RPC server is bound to localhost"`
 	OnionProxy           string        `long:"onion" description:"Connect to tor hidden services via SOCKS5 proxy (eg. 127.0.0.1:9050)"`
 	OnionProxyPass       string        `long:"onionpass" default-mask:"-" description:"Password for onion proxy server"`

peer/peer.go

@@ -276,6 +276,13 @@ type Config struct {
 	// connection detecting and disconnect logic since they intentionally
 	// do so for testing purposes.
 	AllowSelfConns bool
+
+	// DisableStallHandler if true, then the stall handler that attempts to
+	// disconnect from peers that appear to be taking too long to respond
+	// to requests won't be activated. This can be useful in certain simnet
+	// scenarios where the stall behaver isn't important to the system
+	// under test.
+	DisableStallHandler bool
 }
 
 // minUint32 is a helper function to return the minimum of two uint32s.
@@ -2152,9 +2159,14 @@ func (p *Peer) start() error {
 	}
 	log.Debugf("Connected to %s", p.Addr())
 
+	// If the stall handler is disabled, then we don't need to launch the
+	// goroutine that will attempt to boot peers that seem to be lagging.
+	if !p.cfg.DisableStallHandler {
+		go p.stallHandler()
+	}
+
 	// The protocol has been negotiated successfully so start processing input
 	// and output messages.
-	go p.stallHandler()
 	go p.inHandler()
 	go p.queueHandler()
 	go p.outHandler()

server.go

@@ -2054,17 +2054,18 @@ func newPeerConfig(sp *serverPeer) *peer.Config {
 			// other implementations' alert messages, we will not relay theirs.
 			OnAlert: nil,
 		},
-		NewestBlock:       sp.newestBlock,
-		HostToNetAddress:  sp.server.addrManager.HostToNetAddress,
-		Proxy:             cfg.Proxy,
-		UserAgentName:     userAgentName,
-		UserAgentVersion:  userAgentVersion,
-		UserAgentComments: cfg.UserAgentComments,
-		ChainParams:       sp.server.chainParams,
-		Services:          sp.server.services,
-		DisableRelayTx:    cfg.BlocksOnly,
-		ProtocolVersion:   peer.MaxProtocolVersion,
-		TrickleInterval:   cfg.TrickleInterval,
+		NewestBlock:         sp.newestBlock,
+		HostToNetAddress:    sp.server.addrManager.HostToNetAddress,
+		Proxy:               cfg.Proxy,
+		UserAgentName:       userAgentName,
+		UserAgentVersion:    userAgentVersion,
+		UserAgentComments:   cfg.UserAgentComments,
+		ChainParams:         sp.server.chainParams,
+		Services:            sp.server.services,
+		DisableRelayTx:      cfg.BlocksOnly,
+		ProtocolVersion:     peer.MaxProtocolVersion,
+		TrickleInterval:     cfg.TrickleInterval,
+		DisableStallHandler: cfg.DisableStallHandler,
 	}
 }