add relay connection error case

Author: dennis-tra

db/errors.go

@@ -35,6 +35,8 @@ var KnownErrors = map[string]string{
 	"can't assign requested address":             models.NetErrorCantAssignRequestedAddress, // transient error
 	"cannot assign requested address":            models.NetErrorCantAssignRequestedAddress, // transient error
 	"connection gated":                           models.NetErrorConnectionGated,            // transient error
+	"RESOURCE_LIMIT_EXCEEDED (201)":              models.NetErrorCantConnectOverRelay,       // transient error
+	"NO_RESERVATION (204)":                       models.NetErrorCantConnectOverRelay,       // permanent error
 }
 
 var ErrorStr = map[string]string{}
@@ -74,6 +76,8 @@ var knownErrorsPrecedence = []string{
 	"failed to negotiate stream multiplexer",
 	"resource limit exceeded",
 	"Write on stream",
+	"RESOURCE_LIMIT_EXCEEDED (201)",
+	"NO_RESERVATION (204)",
 }
 
 // NetError extracts the appropriate error type from the given error.

db/migrations/000026_add_net_errors.up.sql

@@ -3,6 +3,7 @@ BEGIN;
 ALTER TYPE net_error ADD VALUE 'connection_reset_by_peer';
 ALTER TYPE net_error ADD VALUE 'cant_assign_requested_address';
 ALTER TYPE net_error ADD VALUE 'connection_gated';
+ALTER TYPE net_error ADD VALUE 'cant_connect_over_relay';
 ALTER TYPE net_error RENAME VALUE 'no_public_ip' TO 'no_ip_address';
 
 CREATE OR REPLACE FUNCTION calc_max_failed_visits(

db/models/boil_types.go

@@ -144,7 +144,7 @@ func (c *Crawler) connect(ctx context.Context, pi peer.AddrInfo) error {
 
 	var (
 		retry      int   = 0
-		maxRetries int   = 2
+		maxRetries int   = 3
 		firstErr   error = nil
 	)
 
@@ -177,8 +177,15 @@ func (c *Crawler) connect(ctx context.Context, pi peer.AddrInfo) error {
 
 		switch true {
 		case strings.Contains(err.Error(), db.ErrorStr[models.NetErrorConnectionRefused]):
+			// Might be transient because the remote doesn't want us to connect. Try again!
 		case strings.Contains(err.Error(), db.ErrorStr[models.NetErrorConnectionGated]):
+			// Hints at a configuration issue but could be transient. Try again!
 		case strings.Contains(err.Error(), db.ErrorStr[models.NetErrorCantAssignRequestedAddress]):
+			// Transient error due to local UDP issues. Try again!
+			maxRetries = 10 // increase the maximum number of retries as the error _should_ go away
+		case strings.Contains(err.Error(), db.ErrorStr["RESOURCE_LIMIT_EXCEEDED (201)"]): // thrown by a circuit relay
+			// We already have too many open connections over a relay. Try again!
+			maxRetries = 10 // increase the maximum number of retries as the error _should_ go away
 		default:
 			if errors.Is(err, context.DeadlineExceeded) {
 				err = firstErr