Refactoring of slow and fastpath handling

This changes clarifies a chunk of code related to receiving
data and handle slow and fast path pdus.

6 files changed, 71 insertions, 51 deletions

diff --git a/constants.h b/constants.h
index 267522b..512a35e 100644
--- a/constants.h
+++ b/constants.h
@@ -2,6 +2,7 @@
    rdesktop: A Remote Desktop Protocol client.
    Miscellaneous protocol constants
    Copyright (C) Matthew Chapman 1999-2008
+   Copyright 2017-2018 Henrik Andersson <hean01@cendio.se> for Cendio AB
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -36,9 +37,6 @@
 #define FASTPATH_OUTPUT_SECURE_CHECKSUM 0x1
 #define FASTPATH_OUTPUT_ENCRYPTED       0x2
 
-#define IS_FASTPATH(hdr) ((hdr & 0x03) == FASTPATH_OUTPUT_ACTION_FASTPATH)
-#define IS_SLOWPATH(hdr) ((hdr) == FASTPATH_OUTPUT_ACTION_X224)
-
 /* [MS-RDPBCGR] 2.2.9.1.2.1 */
 /* adjusted for position in updateHeader */
 #define FASTPATH_UPDATETYPE_ORDERS		0x0
diff --git a/iso.c b/iso.c
index eac4274..278f32a 100644
--- a/iso.c
+++ b/iso.c
@@ -3,7 +3,7 @@
    Protocol services - ISO layer
    Copyright (C) Matthew Chapman <matthewc.unsw.edu.au> 1999-2008
    Copyright 2005-2011 Peter Astrand <astrand@cendio.se> for Cendio AB
-   Copyright 2012-2017 Henrik Andersson <hean01@cendio.se> for Cendio AB
+   Copyright 2012-2018 Henrik Andersson <hean01@cendio.se> for Cendio AB
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -98,7 +98,7 @@ iso_send_connection_request(char *username, uint32 neg_proto)
 
 /* Receive a message on the ISO layer, return code */
 static STREAM
-iso_recv_msg(uint8 * code, uint8 * rdpver)
+iso_recv_msg(uint8 * code, RD_BOOL *is_fastpath, uint8 *fastpath_hdr)
 {
 	STREAM s;
 	uint16 length;
@@ -107,16 +107,23 @@ iso_recv_msg(uint8 * code, uint8 * rdpver)
 	s = tcp_recv(NULL, 4);
 	if (s == NULL)
 		return NULL;
-	in_uint8(s, version);
-	if (rdpver != NULL)
-		*rdpver = version;
-	if (IS_SLOWPATH(version))
+
+	in_uint8(s, version); /* T.123 version or Fastpath output header */
+
+	/* detect if this is a slow or fast path PDU */
+	*fastpath_hdr = 0x00;
+	*is_fastpath = False;
+	if (version == T123_HEADER_VERSION)
 	{
 		in_uint8s(s, 1);		/* reserved */
 		in_uint16_be(s, length);	/* length */
 	}
 	else
 	{
+		/* if version is not an expected T.123 version eg. 3, then this
+		   stream is a fast path pdu */
+		*is_fastpath = True;
+		*fastpath_hdr = version;
 		in_uint8(s, length); /* length1 */
 		if (length & 0x80)
 		{
@@ -125,16 +132,20 @@ iso_recv_msg(uint8 * code, uint8 * rdpver)
 			next_be(s, length);
 		}
 	}
+
 	if (length < 4)
 	{
 		logger(Protocol, Error, "iso_recv_msg(), bad packet header, length < 4");
 		return NULL;
 	}
+
 	s = tcp_recv(s, length - 4);
 	if (s == NULL)
 		return NULL;
-	if (IS_FASTPATH(version))
+
+	if (*is_fastpath == True)
 		return s;
+
 	in_uint8s(s, 1);	/* hdrlen */
 	in_uint8(s, *code);
 	if (*code == ISO_PDU_DT)
@@ -180,17 +191,18 @@ iso_send(STREAM s)
 
 /* Receive ISO transport data packet */
 STREAM
-iso_recv(uint8 * rdpver)
+iso_recv(RD_BOOL *is_fastpath, uint8 *fastpath_hdr)
 {
 	STREAM s;
 	uint8 code = 0;
 
-	s = iso_recv_msg(&code, rdpver);
+	s = iso_recv_msg(&code, is_fastpath, fastpath_hdr);
 	if (s == NULL)
 		return NULL;
-	if (rdpver != NULL)
-		if (IS_FASTPATH(*rdpver))
-			return s;
+
+	if (*is_fastpath == True)
+		return s;
+
 	if (code != ISO_PDU_DT)
 	{
 		logger(Protocol, Error, "iso_recv(), expected ISO_PDU_DT, got 0x%x", code);
@@ -208,6 +220,8 @@ iso_connect(char *server, char *username, char *domain, char *password,
 	STREAM s;
 	uint8 code;
 	uint32 neg_proto;
+	RD_BOOL is_fastpath;
+	uint8 fastpath_hdr;
 
 	g_negotiate_rdp_protocol = True;
 
@@ -236,7 +250,7 @@ iso_connect(char *server, char *username, char *domain, char *password,
 
 	iso_send_connection_request(username, neg_proto);
 
-	s = iso_recv_msg(&code, NULL);
+	s = iso_recv_msg(&code, &is_fastpath, &fastpath_hdr);
 	if (s == NULL)
 		return False;
 
diff --git a/mcs.c b/mcs.c
index a68174c..f3a4c23 100644
--- a/mcs.c
+++ b/mcs.c
@@ -3,6 +3,7 @@
    Protocol services - Multipoint Communications Service
    Copyright (C) Matthew Chapman <matthewc.unsw.edu.au> 1999-2008
    Copyright 2005-2011 Peter Astrand <astrand@cendio.se> for Cendio AB
+   Copyright 2018 Henrik Andersson <hean01@cendio.com> for Cendio AB
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -90,8 +91,12 @@ mcs_recv_connect_response(STREAM mcs_data)
 	uint8 result;
 	int length;
 	STREAM s;
+	RD_BOOL is_fastpath;
+	uint8 fastpath_hdr;
+
 	logger(Protocol, Debug, "%s()", __func__);
-	s = iso_recv(NULL);
+	s = iso_recv(&is_fastpath, &fastpath_hdr);
+
 	if (s == NULL)
 		return False;
 
@@ -160,10 +165,14 @@ mcs_send_aurq(void)
 static RD_BOOL
 mcs_recv_aucf(uint16 * mcs_userid)
 {
+	RD_BOOL is_fastpath;
+	uint8 fastpath_hdr;
 	uint8 opcode, result;
 	STREAM s;
+
 	logger(Protocol, Debug, "%s()", __func__);
-	s = iso_recv(NULL);
+	s = iso_recv(&is_fastpath, &fastpath_hdr);
+
 	if (s == NULL)
 		return False;
 
@@ -209,10 +218,14 @@ mcs_send_cjrq(uint16 chanid)
 static RD_BOOL
 mcs_recv_cjcf(void)
 {
+	RD_BOOL is_fastpath;
+	uint8 fastpath_hdr;
 	uint8 opcode, result;
 	STREAM s;
+
 	logger(Protocol, Debug, "%s()", __func__);
-	s = iso_recv(NULL);
+	s = iso_recv(&is_fastpath, &fastpath_hdr);
+
 	if (s == NULL)
 		return False;
 
@@ -303,17 +316,18 @@ mcs_send(STREAM s)
 
 /* Receive an MCS transport data packet */
 STREAM
-mcs_recv(uint16 * channel, uint8 * rdpver)
+mcs_recv(uint16 * channel, RD_BOOL *is_fastpath, uint8 *fastpath_hdr)
 {
 	uint8 opcode, appid, length;
 	STREAM s;
 
-	s = iso_recv(rdpver);
+	s = iso_recv(is_fastpath, fastpath_hdr);
 	if (s == NULL)
 		return NULL;
-	if (rdpver != NULL)
-		if (*rdpver != 3)
-			return s;
+
+	if (*is_fastpath == True)
+		return s;
+
 	in_uint8(s, opcode);
 	appid = opcode >> 2;
 	if (appid != MCS_SDIN)
diff --git a/proto.h b/proto.h
index a5aa2f5..7ce19b4 100644
--- a/proto.h
+++ b/proto.h
@@ -82,7 +82,7 @@ void ewmh_init(void);
 /* iso.c */
 STREAM iso_init(int length);
 void iso_send(STREAM s);
-STREAM iso_recv(uint8 * rdpver);
+STREAM iso_recv(RD_BOOL *is_fastpath, uint8 *fastpath_hdr);
 RD_BOOL iso_connect(char *server, char *username, char *domain, char *password, RD_BOOL reconnect,
 		    uint32 * selected_protocol);
 void iso_disconnect(void);
@@ -95,7 +95,7 @@ void licence_process(STREAM s);
 STREAM mcs_init(int length);
 void mcs_send_to_channel(STREAM s, uint16 channel);
 void mcs_send(STREAM s);
-STREAM mcs_recv(uint16 * channel, uint8 * rdpver);
+STREAM mcs_recv(uint16 * channel, RD_BOOL *is_fastpath, uint8 *fastpath_hdr);
 RD_BOOL mcs_connect_start(char *server, char *username, char *domain, char *password,
 			  RD_BOOL reconnect, uint32 * selected_protocol);
 RD_BOOL mcs_connect_finalize(STREAM s);
@@ -199,7 +199,7 @@ STREAM sec_init(uint32 flags, int maxlen);
 void sec_send_to_channel(STREAM s, uint32 flags, uint16 channel);
 void sec_send(STREAM s, uint32 flags);
 void sec_process_mcs_data(STREAM s);
-STREAM sec_recv(uint8 * rdpver);
+STREAM sec_recv(RD_BOOL * is_fastpath);
 RD_BOOL sec_connect(char *server, char *username, char *domain, char *password, RD_BOOL reconnect);
 void sec_disconnect(void);
 void sec_reset_state(void);
diff --git a/rdp.c b/rdp.c
index 749bf1b..95a37ad 100644
--- a/rdp.c
+++ b/rdp.c
@@ -3,7 +3,7 @@
    Protocol services - RDP layer
    Copyright (C) Matthew Chapman <matthewc.unsw.edu.au> 1999-2008
    Copyright 2003-2011 Peter Astrand <astrand@cendio.se> for Cendio AB
-   Copyright 2011-2017 Henrik Andersson <hean01@cendio.se> for Cendio AB
+   Copyright 2011-2018 Henrik Andersson <hean01@cendio.se> for Cendio AB
    Copyright 2017 Karl Mikaelsson <derfian@cendio.se> for Cendio AB
 
    This program is free software: you can redistribute it and/or modify
@@ -96,22 +96,17 @@ static void rdp_out_unistr(STREAM s, char *string, int len);
 static STREAM
 rdp_recv(uint8 * type)
 {
+	RD_BOOL is_fastpath;
 	static STREAM rdp_s;
 	uint16 length, pdu_type;
-	uint8 rdpver;
 
 	if ((rdp_s == NULL) || (g_next_packet >= rdp_s->end) || (g_next_packet == NULL))
 	{
-		rdp_s = sec_recv(&rdpver);
+		rdp_s = sec_recv(&is_fastpath);
 		if (rdp_s == NULL)
 			return NULL;
-		if (rdpver == 0xff)
-		{
-			g_next_packet = rdp_s->end;
-			*type = 0;
-			return rdp_s;
-		}
-		else if (rdpver != 3)
+
+		if (is_fastpath == True)
 		{
 			/* process_ts_fp_updates moves g_next_packet */
 			process_ts_fp_updates(rdp_s);
diff --git a/secure.c b/secure.c
index c093bcc..b829a02 100644
--- a/secure.c
+++ b/secure.c
@@ -3,7 +3,7 @@
    Protocol services - RDP encryption and licensing
    Copyright (C) Matthew Chapman <matthewc.unsw.edu.au> 1999-2008
    Copyright 2005-2011 Peter Astrand <astrand@cendio.se> for Cendio AB
-   Copyright 2017 Henrik Andersson <hean01@cendio.se> for Cendio AB
+   Copyright 2017-2018 Henrik Andersson <hean01@cendio.se> for Cendio AB
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -842,26 +842,27 @@ sec_process_mcs_data(STREAM s)
 
 /* Receive secure transport packet */
 STREAM
-sec_recv(uint8 * rdpver)
+sec_recv(RD_BOOL *is_fastpath)
 {
+	uint8 fastpath_hdr;
 	uint16 sec_flags;
 	uint16 channel;
 	STREAM s;
 
-	while ((s = mcs_recv(&channel, rdpver)) != NULL)
+	while ((s = mcs_recv(&channel, is_fastpath, &fastpath_hdr)) != NULL)
 	{
-		if (rdpver != NULL)
+		if (*is_fastpath == True)
 		{
-			if (*rdpver != 3)
+			/* If fastpath packet is encrypted, read data
+			   signature and decrypt */
+			if (fastpath_hdr & FASTPATH_OUTPUT_ENCRYPTED)
 			{
-				if (*rdpver & 0x80)
-				{
-					in_uint8s(s, 8);	/* signature */
-					sec_decrypt(s->p, s->end - s->p);
-				}
-				return s;
+				in_uint8s(s, 8);	/* signature */
+				sec_decrypt(s->p, s->end - s->p);
 			}
+			return s;
 		}
+
 		if (g_encryption || (!g_licence_issued && !g_licence_error_result))
 		{
 			/* TS_SECURITY_HEADER */
@@ -926,9 +927,7 @@ sec_recv(uint8 * rdpver)
 		if (channel != MCS_GLOBAL_CHANNEL)
 		{
 			channel_process(s, channel);
-			if (rdpver != NULL)
-				*rdpver = 0xff;
-			return s;
+			continue;
 		}
 
 		return s;