mox!

moxio/prefixconn.go

@@ -0,0 +1,25 @@
+package moxio
+
+import (
+	"io"
+	"net"
+)
+
+// PrefixConn is a net.Conn prefixed with a reader that is first drained.
+// Used for STARTTLS where already did a buffered read of initial TLS data.
+type PrefixConn struct {
+	PrefixReader io.Reader // If not nil, reads are fulfilled from here. It is cleared when a read returns io.EOF.
+	net.Conn
+}
+
+// Read returns data when PrefixReader when not nil, and net.Conn otherwise.
+func (c *PrefixConn) Read(buf []byte) (int, error) {
+	if c.PrefixReader != nil {
+		n, err := c.PrefixReader.Read(buf)
+		if err == io.EOF {
+			c.PrefixReader = nil
+		}
+		return n, err
+	}
+	return c.Conn.Read(buf)
+}