common/prpc, tools/cmd/cproto: prpc client

server/prpc/error.go

Index: server/prpc/error.go
diff --git a/server/prpc/error.go b/server/prpc/error.go
index 950ef99f65c3787f36c451cf1653057d8e3c54a7..f19e9be9ea56eb4feeacb69ecedaefb32c20069b 100644
--- a/server/prpc/error.go
+++ b/server/prpc/error.go
@@ -19,6 +19,10 @@ func (e *httpError) Error() string {
 	return fmt.Sprintf("HTTP %d: %s", e.status, e.err)
 }
 
+func (e *httpError) InnerError() error {
+	return e.err
+}
+
 // withStatus wraps an error with an HTTP status.
 // If err is nil, returns nil.
 func withStatus(err error, status int) *httpError {