State active (#1260)

* Require at least Go 1.15

* Fix StateActive state

* Don't panic when idle connections get closed

go.mod

@@ -1,6 +1,6 @@
 module github.com/valyala/fasthttp
 
-go 1.12
+go 1.15
 
 require (
 	github.com/andybalholm/brotli v1.0.4

server.go

@@ -2138,7 +2138,7 @@ func (s *Server) serveConn(c net.Conn) (err error) {
 		if connRequestNum > 1 {
 			if d := s.idleTimeout(); d > 0 {
 				if err := c.SetReadDeadline(time.Now().Add(d)); err != nil {
-					panic(fmt.Sprintf("BUG: error in SetReadDeadline(%s): %s", d, err))
+					break
 				}
 			}
 		}
@@ -2178,15 +2178,17 @@ func (s *Server) serveConn(c net.Conn) (err error) {
 		ctx.Response.secureErrorLogMessage = s.SecureErrorLogMessage
 
 		if err == nil {
+			s.setState(c, StateActive)
+
 			if s.ReadTimeout > 0 {
 				if err := c.SetReadDeadline(time.Now().Add(s.ReadTimeout)); err != nil {
-					panic(fmt.Sprintf("BUG: error in SetReadDeadline(%s): %s", s.ReadTimeout, err))
+					break
 				}
 			} else if s.IdleTimeout > 0 && connRequestNum > 1 {
 				// If this was an idle connection and the server has an IdleTimeout but
 				// no ReadTimeout then we should remove the ReadTimeout.
 				if err := c.SetReadDeadline(zeroTime); err != nil {
-					panic(fmt.Sprintf("BUG: error in SetReadDeadline(zeroTime): %s", err))
+					break
 				}
 			}
 			if s.DisableHeaderNamesNormalizing {
@@ -2238,11 +2240,6 @@ func (s *Server) serveConn(c net.Conn) (err error) {
 				}
 			}
 
-			if err == nil {
-				// If we read any bytes off the wire, we're active.
-				s.setState(c, StateActive)
-			}
-
 			if (s.ReduceMemoryUsage && br.Buffered() == 0) || err != nil {
 				releaseReader(s, br)
 				br = nil