From 3a074450d7af4a80a8cdfc6b586da2b021fb0f37 Mon Sep 17 00:00:00 2001
From: Laxmikant Rashinkar <LK.Rashinkar@gmail.com>
Date: Wed, 6 Nov 2013 19:48:22 -0800
Subject: [PATCH] changed bulk compression logic

---
 libxrdp/xrdp_mppc_enc.c | 29 ++++++++++++++++++++++++---
 libxrdp/xrdp_rdp.c      | 43 +++++++++++++++++++----------------------
 2 files changed, 46 insertions(+), 26 deletions(-)

diff --git a/libxrdp/xrdp_mppc_enc.c b/libxrdp/xrdp_mppc_enc.c
index 05aa6bb6..15125d54 100644
--- a/libxrdp/xrdp_mppc_enc.c
+++ b/libxrdp/xrdp_mppc_enc.c
@@ -573,18 +573,21 @@ compress_rdp_5(struct xrdp_mppc_enc *enc, tui8 *srcData, int len)
     outputBuffer = enc->outputBuffer;
     g_memset(outputBuffer, 0, len);
     enc->flags = PACKET_COMPR_TYPE_64K;
+
     if (enc->first_pkt)
     {
         enc->first_pkt = 0;
         enc->flagsHold |= PACKET_AT_FRONT;
     }
 
-    if ((enc->historyOffset + len) > enc->buf_len)
+    if ((enc->historyOffset + len) >= enc->buf_len)
     {
         /* historyBuffer cannot hold srcData - rewind it */
         enc->historyOffset = 0;
-        enc->flagsHold |= PACKET_AT_FRONT;
         g_memset(hash_table, 0, enc->buf_len * 2);
+        g_memset(enc->historyBuffer, 0, enc->buf_len); // added
+        enc->first_pkt = 0;
+        enc->flagsHold |= PACKET_AT_FRONT;
     }
 
     /* point to next free byte in historyBuffer */
@@ -602,7 +605,7 @@ compress_rdp_5(struct xrdp_mppc_enc *enc, tui8 *srcData, int len)
     /* first 2 bytes,because minimum LoM is 3                           */
     if (historyOffset == 0)
     {
-        /* encode first two bytes are literals */
+        /* encode first two bytes as literals */
         for (x = 0; x < 2; x++)
         {
             data = *(historyPointer + x);
@@ -974,8 +977,14 @@ compress_rdp_5(struct xrdp_mppc_enc *enc, tui8 *srcData, int len)
         /* give up */
         enc->historyOffset = 0;
         g_memset(hash_table, 0, enc->buf_len * 2);
+        g_memset(enc->historyBuffer, 0, enc->buf_len);
         enc->flagsHold |= PACKET_FLUSHED;
         enc->first_pkt = 1;
+
+        g_memcpy(enc->outputBuffer, srcData, len);
+        enc->bytes_in_opb = len;
+        enc->flags = 0x81;
+
         return 1;
     }
     else if (opb_index + 1 > len)
@@ -984,8 +993,14 @@ compress_rdp_5(struct xrdp_mppc_enc *enc, tui8 *srcData, int len)
         /* give up */
         enc->historyOffset = 0;
         g_memset(hash_table, 0, enc->buf_len * 2);
+        g_memset(enc->historyBuffer, 0, enc->buf_len);
         enc->flagsHold |= PACKET_FLUSHED;
         enc->first_pkt = 1;
+
+        g_memcpy(enc->outputBuffer, srcData, len);
+        enc->bytes_in_opb = len;
+        enc->flags = 0x81;
+
         return 1;
     }
 
@@ -1000,8 +1015,14 @@ compress_rdp_5(struct xrdp_mppc_enc *enc, tui8 *srcData, int len)
         /* give up */
         enc->historyOffset = 0;
         g_memset(hash_table, 0, enc->buf_len * 2);
+        g_memset(enc->historyBuffer, 0, enc->buf_len);
         enc->flagsHold |= PACKET_FLUSHED;
         enc->first_pkt = 1;
+
+        g_memcpy(enc->outputBuffer, srcData, len);
+        enc->bytes_in_opb = len;
+        enc->flags = 0x81;
+
         return 1;
     }
     enc->flags |= PACKET_COMPRESSED;
@@ -1011,6 +1032,8 @@ compress_rdp_5(struct xrdp_mppc_enc *enc, tui8 *srcData, int len)
     enc->flagsHold = 0;
     DLOG(("\n"));
 
+    //g_writeln("compression ratio: %f", (float) len / (float) enc->bytes_in_opb);
+
     return 1;
 }
 
diff --git a/libxrdp/xrdp_rdp.c b/libxrdp/xrdp_rdp.c
index 5f358fca..9147287e 100644
--- a/libxrdp/xrdp_rdp.c
+++ b/libxrdp/xrdp_rdp.c
@@ -433,29 +433,26 @@ xrdp_rdp_send_data(struct xrdp_rdp *self, struct stream *s,
                    "tocomplen %d", mppc_enc->flags, mppc_enc->bytes_in_opb,
                    mppc_enc->historyOffset, tocomplen));
 
-            if (mppc_enc->flags & RDP_MPPC_COMPRESSED)
-            {
-                clen = mppc_enc->bytes_in_opb + 18;
-                pdulen = clen;
-                ctype = mppc_enc->flags;
-                iso_offset = (int)(s->iso_hdr - s->data);
-                mcs_offset = (int)(s->mcs_hdr - s->data);
-                sec_offset = (int)(s->sec_hdr - s->data);
-                rdp_offset = (int)(s->rdp_hdr - s->data);
-
-                /* outputBuffer has 64 bytes preceding it */
-                ls.data = mppc_enc->outputBuffer - (rdp_offset + 18);
-                ls.p = ls.data + rdp_offset;
-                ls.end = ls.p + clen;
-                ls.size = clen;
-                ls.iso_hdr = ls.data + iso_offset;
-                ls.mcs_hdr = ls.data + mcs_offset;
-                ls.sec_hdr = ls.data + sec_offset;
-                ls.rdp_hdr = ls.data + rdp_offset;
-                ls.channel_hdr = 0;
-                ls.next_packet = 0;
-                s = &ls;
-            }
+            clen = mppc_enc->bytes_in_opb + 18;
+            pdulen = clen;
+            ctype = mppc_enc->flags;
+            iso_offset = (int)(s->iso_hdr - s->data);
+            mcs_offset = (int)(s->mcs_hdr - s->data);
+            sec_offset = (int)(s->sec_hdr - s->data);
+            rdp_offset = (int)(s->rdp_hdr - s->data);
+
+            /* outputBuffer has 64 bytes preceding it */
+            ls.data = mppc_enc->outputBuffer - (rdp_offset + 18);
+            ls.p = ls.data + rdp_offset;
+            ls.end = ls.p + clen;
+            ls.size = clen;
+            ls.iso_hdr = ls.data + iso_offset;
+            ls.mcs_hdr = ls.data + mcs_offset;
+            ls.sec_hdr = ls.data + sec_offset;
+            ls.rdp_hdr = ls.data + rdp_offset;
+            ls.channel_hdr = 0;
+            ls.next_packet = 0;
+            s = &ls;
         }
         else
         {