From 79b9813df553ac63c3f8bcfda6e42989dd8abe40 Mon Sep 17 00:00:00 2001
From: Henrik Andersson <hean01@cendio.com>
Date: Fri, 20 Jan 2017 10:32:46 +0100
Subject: [PATCH] Minor refactor of rdp_out_unistr()

The logon packets wants a mandatory null termination
to be written to stream if not string is available.
The current design was to do if statements at those
points to handle this. Refactored that code into
function rdp_out_unistr_mandatory_null() for a
cleaner code when building up the packets.
---
 rdp.c | 83 +++++++++++++++++++++--------------------------------------
 1 file changed, 29 insertions(+), 54 deletions(-)

diff --git a/rdp.c b/rdp.c
index 4eb70d1..1b5a68c 100644
--- a/rdp.c
+++ b/rdp.c
@@ -174,6 +174,18 @@ rdp_send_data(STREAM s, uint8 data_pdu_type)
 	sec_send(s, g_encryption ? SEC_ENCRYPT : 0);
 }
 
+/* Output a string in Unicode with mandatory null termination. If
+   string is NULL or len is 0, write an unicode null termination to
+   stream. */
+void
+rdp_out_unistr_mandatory_null(STREAM s, char *string, int len)
+{
+	if (string && len > 0)
+		rdp_out_unistr(s, string, len);
+	else
+		out_uint16_le(s, 0);
+}
+
 /* Output a string in Unicode */
 void
 rdp_out_unistr(STREAM s, char *string, int len)
@@ -318,30 +330,11 @@ rdp_send_logon_info(uint32 flags, char *domain, char *user,
 		out_uint16_le(s, len_program);
 		out_uint16_le(s, len_directory);
 
-		if (0 < len_domain)
-			rdp_out_unistr(s, domain, len_domain);
-		else
-			out_uint16_le(s, 0);
-
-		if (0 < len_user)
-			rdp_out_unistr(s, user, len_user);
-		else
-			out_uint16_le(s, 0);
-
-		if (0 < len_password)
-			rdp_out_unistr(s, password, len_password);
-		else
-			out_uint16_le(s, 0);
-
-		if (0 < len_program)
-			rdp_out_unistr(s, program, len_program);
-		else
-			out_uint16_le(s, 0);
-
-		if (0 < len_directory)
-			rdp_out_unistr(s, directory, len_directory);
-		else
-			out_uint16_le(s, 0);
+		rdp_out_unistr_mandatory_null(s, domain, len_domain);
+		rdp_out_unistr_mandatory_null(s, user, len_user);
+		rdp_out_unistr_mandatory_null(s, password, len_password);
+		rdp_out_unistr_mandatory_null(s, program, len_program);
+		rdp_out_unistr_mandatory_null(s, directory, len_directory);
 	}
 	else
 	{
@@ -401,46 +394,28 @@ rdp_send_logon_info(uint32 flags, char *domain, char *user,
 		out_uint16_le(s, len_program);
 		out_uint16_le(s, len_directory);
 
-		if (0 < len_domain)
-			rdp_out_unistr(s, domain, len_domain);
-		else
-			out_uint16_le(s, 0);	/* mandatory 2 bytes null terminator */
+		rdp_out_unistr_mandatory_null(s, domain, len_domain);
+		rdp_out_unistr_mandatory_null(s, user, len_user);
 
-		if (0 < len_user)
-			rdp_out_unistr(s, user, len_user);
-		else
-			out_uint16_le(s, 0);	/* mandatory 2 bytes null terminator */
-
-		if (0 < len_password)
+		if (g_redirect == True && 0 < g_redirect_cookie_len)
 		{
-			if (g_redirect == True && 0 < g_redirect_cookie_len)
-			{
-				out_uint8p(s, g_redirect_cookie, g_redirect_cookie_len);
-			}
-			else
-			{
-				rdp_out_unistr(s, password, len_password);
-			}
+			out_uint8p(s, g_redirect_cookie, g_redirect_cookie_len);
 		}
 		else
-			out_uint16_le(s, 0);	/* mandatory 2 bytes null terminator */
+		{
+			rdp_out_unistr_mandatory_null(s, password, len_password);
+		}
 
-		if (0 < len_program)
-			rdp_out_unistr(s, program, len_program);
-		else
-			out_uint16_le(s, 0);	/* mandatory 2 bytes null terminator */
 
-		if (0 < len_directory)
-			rdp_out_unistr(s, directory, len_directory);
-		else
-			out_uint16_le(s, 0);	/* mandatory 2 bytes null terminator */
+		rdp_out_unistr_mandatory_null(s, program, len_program);
+		rdp_out_unistr_mandatory_null(s, directory, len_directory);
 
 		/* TS_EXTENDED_INFO_PACKET */
 		out_uint16_le(s, 2);	/* clientAddressFamily = AF_INET */
-		out_uint16_le(s, len_ip);	/* cbClientAddress, Length of client ip */
-		rdp_out_unistr(s, ipaddr, len_ip - 2);	/* clientAddress */
+		out_uint16_le(s, len_ip);	/* cbClientAddress */
+		rdp_out_unistr_mandatory_null(s, ipaddr, len_ip - 2);	/* clientAddress */
 		out_uint16_le(s, len_dll);	/* cbClientDir */
-		rdp_out_unistr(s, "C:\\WINNT\\System32\\mstscax.dll", len_dll - 2);	/* clientDir */
+		rdp_out_unistr_mandatory_null(s, "C:\\WINNT\\System32\\mstscax.dll", len_dll - 2);	/* clientDir */
 
 		/* TS_TIME_ZONE_INFORMATION */
 		tzone = (mktime(gmtime(&t)) - mktime(localtime(&t))) / 60;