Use communicationError for network errors

conn.go

@@ -69,6 +69,12 @@ func (s transactionStatus) String() string {
 	panic("not reached")
 }
 
+// Any failure in communication should be raised as a communicationError to
+// allow errRecover to know what happened.
+type communicationError struct {
+	error
+}
+
 type conn struct {
 	c         net.Conn
 	buf       *bufio.Reader
@@ -153,7 +159,7 @@ func Open(name string) (_ driver.Conn, err error) {
 
 	c, err := net.Dial(network(o))
 	if err != nil {
-		return nil, err
+		return nil, communicationError{err}
 	}
 
 	cn := &conn{c: c}
@@ -556,7 +562,7 @@ func (cn *conn) send(m *writeBuf) {
 
 	_, err := cn.c.Write(*m)
 	if err != nil {
-		panic(err)
+		panic(communicationError{err})
 	}
 }
 
@@ -574,7 +580,7 @@ func (cn *conn) recvMessage() (byte, *readBuf, error) {
 	x := cn.scratch[:5]
 	_, err := io.ReadFull(cn.buf, x)
 	if err != nil {
-		return 0, nil, err
+		return 0, nil, communicationError{err}
 	}
 	t := x[0]
 
@@ -588,7 +594,7 @@ func (cn *conn) recvMessage() (byte, *readBuf, error) {
 	}
 	_, err = io.ReadFull(cn.buf, y)
 	if err != nil {
-		return 0, nil, err
+		return 0, nil, communicationError{err}
 	}
 
 	return t, (*readBuf)(&y), nil

conn_test.go

@@ -412,7 +412,7 @@ func TestBadConn(t *testing.T) {
 
 	func() {
 		defer errRecover(&err)
-		panic(io.EOF)
+		panic(communicationError{io.EOF})
 	}()
 
 	if err != driver.ErrBadConn {

error.go

@@ -3,8 +3,6 @@ package pq
 import (
 	"database/sql/driver"
 	"fmt"
-	"io"
-	"net"
 	"runtime"
 )
 
@@ -452,14 +450,10 @@ func errRecover(err *error) {
 		} else {
 			*err = v
 		}
-	case *net.OpError:
+	case communicationError:
 		*err = driver.ErrBadConn
 	case error:
-		if v == io.EOF || v.(error).Error() == "remote error: handshake failure" {
-			*err = driver.ErrBadConn
-		} else {
-			*err = v
-		}
+		*err = v
 
 	default:
 		panic(fmt.Sprintf("unknown error: %#v", e))