ssh: add debug print at the lowest level
This is a simple minded, fast print, suitable for debugging timing
sensitive issues.
Change-Id: I9ae3df5fe86f1883c1fa9265b6f7f9a98d33747e
Reviewed-on: https://go-review.googlesource.com/36054
Run-TryBot: Han-Wen Nienhuys <hanwen@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/ssh/mux_test.go b/ssh/mux_test.go
index 591aae8..25d2181 100644
--- a/ssh/mux_test.go
+++ b/ssh/mux_test.go
@@ -499,4 +499,7 @@
if debugHandshake {
t.Error("handshake debug switched on")
}
+ if debugTransport {
+ t.Error("transport debug switched on")
+ }
}
diff --git a/ssh/transport.go b/ssh/transport.go
index fd19932..e9c3baf 100644
--- a/ssh/transport.go
+++ b/ssh/transport.go
@@ -8,8 +8,13 @@
"bufio"
"errors"
"io"
+ "log"
)
+// debugTransport if set, will print packet types as they go over the
+// wire. No message decoding is done, to minimize the impact on timing.
+const debugTransport = false
+
const (
gcmCipherID = "aes128-gcm@openssh.com"
aes128cbcID = "aes128-cbc"
@@ -40,7 +45,7 @@
bufReader *bufio.Reader
bufWriter *bufio.Writer
rand io.Reader
-
+ isClient bool
io.Closer
}
@@ -86,6 +91,22 @@
return nil
}
+func (t *transport) printPacket(p []byte, write bool) {
+ if len(p) == 0 {
+ return
+ }
+ who := "server"
+ if t.isClient {
+ who = "client"
+ }
+ what := "read"
+ if write {
+ what = "write"
+ }
+
+ log.Println(what, who, p[0])
+}
+
// Read and decrypt next packet.
func (t *transport) readPacket() (p []byte, err error) {
for {
@@ -97,6 +118,9 @@
break
}
}
+ if debugTransport {
+ t.printPacket(p, false)
+ }
return p, err
}
@@ -141,6 +165,9 @@
}
func (t *transport) writePacket(packet []byte) error {
+ if debugTransport {
+ t.printPacket(packet, true)
+ }
return t.writer.writePacket(t.bufWriter, t.rand, packet)
}
@@ -181,6 +208,8 @@
},
Closer: rwc,
}
+ t.isClient = isClient
+
if isClient {
t.reader.dir = serverKeys
t.writer.dir = clientKeys
