align first byte to allow for A/C and proto compression

[ppp.git] / svr4 / ppp_ahdlc.c

diff --git a/svr4/ppp_ahdlc.c b/svr4/ppp_ahdlc.c
index dc35dda51c9688feb97a53d8eccc0c66259d1f69..ffbe12078fa435a1b7b38af1a98adcd3b2cae75f 100644 (file)
--- a/svr4/ppp_ahdlc.c
+++ b/svr4/ppp_ahdlc.c
@@ -24,7 +24,7 @@
  * OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS,
  * OR MODIFICATIONS.
  *
- * $Id: ppp_ahdlc.c,v 1.3 1995/05/29 06:45:49 paulus Exp $
+ * $Id: ppp_ahdlc.c,v 1.5 1995/10/27 03:57:10 paulus Exp $
  */
 
 /*
@@ -566,6 +566,17 @@ static unsigned paritytab[8] = {
     0x69969669, 0x96696996, 0x96696996, 0x69969669
 };
 
+#define UPDATE_FLAGS(c)        {                               \
+    if ((c) & 0x80)                                    \
+       state->flags |= RCV_B7_1;                       \
+    else                                               \
+       state->flags |= RCV_B7_0;                       \
+    if (paritytab[(c) >> 5] & (1 << ((c) & 0x1F)))     \
+       state->flags |= RCV_ODDP;                       \
+    else                                               \
+       state->flags |= RCV_EVNP;                       \
+}
+
 /*
  * Process received characters.
  */
@@ -596,8 +607,7 @@ unstuff_chars(q, mp)
        }
 
        if ((state->flags & (IFLUSH|ESCAPED)) == 0
-           && state->inlen >= PPP_HDRLEN
-           && (om = state->cur_blk) != 0) {
+           && state->inlen > 0 && (om = state->cur_blk) != 0) {
            /*
             * Process bulk chars as quickly as possible.
             */
@@ -616,26 +626,18 @@ unstuff_chars(q, mp)
                if (c == PPP_FLAG)
                    break;
                ++cp;
-               if (c & 0x80)
-                   state->flags |= RCV_B7_1;
-               else
-                   state->flags |= RCV_B7_0;
-               if (paritytab[c >> 5] & (1 << (c & 0x1F)))
-                   state->flags |= RCV_ODDP;
-               else
-                   state->flags |= RCV_EVNP;
+               UPDATE_FLAGS(c);
                if (c == PPP_ESCAPE) {
                    if (extra > 0) {
                        --extra;
                        ++cpend;
-                   } else if (cp >= cpend) {
+                   }
+                   if (cp >= cpend || (c = *cp) == PPP_FLAG) {
                        state->flags |= ESCAPED;
                        break;
                    }
-                   c = *cp;
-                   if (c == PPP_FLAG)
-                       break;
                    ++cp;
+                   UPDATE_FLAGS(c);
                    c ^= PPP_TRANS;
                }
                *dp++ = c;
@@ -644,19 +646,12 @@ unstuff_chars(q, mp)
            state->inlen += dp - dp0;
            state->infcs = fcs;
            om->b_wptr = dp;
-           if (cp >= cpend)
-               continue;       /* go back and check cp again */
+           if (cp >= mp->b_wptr)
+               continue;       /* advance to the next mblk */
        }
 
        c = *cp++;
-       if (c & 0x80)
-           state->flags |= RCV_B7_1;
-       else
-           state->flags |= RCV_B7_0;
-       if (paritytab[c >> 5] & (1 << (c & 0x1F)))
-           state->flags |= RCV_ODDP;
-       else
-           state->flags |= RCV_EVNP;
+       UPDATE_FLAGS(c);
        if (c == PPP_FLAG) {
            /*
             * End of a frame.
@@ -733,34 +728,26 @@ unstuff_chars(q, mp)
                state->cur_blk = om;
            }
        }
-       *om->b_wptr++ = c;
-       ++state->inlen;
-       state->infcs = PPP_FCS(state->infcs, c);
 
-       if (state->inlen == PPP_HDRLEN) {
+       if (state->inlen == 0) {
            /*
             * We don't do address/control & protocol decompression here,
-            * but we do leave space for the decompressed fields and
-            * arrange for the info field to start on a word boundary.
+            * but we try to put the first byte at an offset such that
+            * the info field starts on a word boundary.  The code here
+            * will do this except for packets with protocol compression
+            * but not address/control compression.
             */
-           dp = om->b_rptr;
-           if (PPP_ADDRESS(dp) == PPP_ALLSTATIONS
-               && PPP_CONTROL(dp) == PPP_UI)
-               dp += 2;
-           if ((*dp & 1) == 0)
-               ++dp;
-           /* dp is now pointing at the last byte of the ppp protocol field */
-           offset = 3 - ((unsigned)dp & 3);
-           if (offset > 0) {
-               dp = om->b_wptr;
-               do {
-                   --dp;
-                   dp[offset] = dp[0];
-               } while (dp > om->b_rptr);
-               om->b_rptr += offset;
-               om->b_wptr += offset;
+           if (c != PPP_ALLSTATIONS) {
+               om->b_wptr += 2;
+               if (c & 1)
+                   ++om->b_wptr;
+               om->b_rptr = om->b_wptr;
            }
        }
+
+       *om->b_wptr++ = c;
+       ++state->inlen;
+       state->infcs = PPP_FCS(state->infcs, c);
     }
 }