p2p/msgrate: return capacity as integer, clamp to max uint32 (#22943)

* p2p/msgrate: return capacity as integer

* eth/protocols/snap: remove conversions

* p2p/msgrate: add overflow test

* p2p/msgrate: make the capacity overflow test actually overflow

* p2p/msgrate: clamp capacity to max int32

* p2p/msgrate: fix min/max confusion

p2p/msgrate/msgrate_test.go

@@ -0,0 +1,28 @@
+// Copyright 2021 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package msgrate
+
+import "testing"
+
+func TestCapacityOverflow(t *testing.T) {
+	tracker := NewTracker(nil, 1)
+	tracker.Update(1, 1, 100000)
+	cap := tracker.Capacity(1, 10000000)
+	if int32(cap) < 0 {
+		t.Fatalf("Negative: %v", int32(cap))
+	}
+}