Changeset 0093ab6 in mainline for uspace/srv/net/tl/tcp/seq_no.c

Timestamp:

2011-09-21T19:56:41Z (14 years ago)

Author:

Jiri Svoboda <jiri@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

032bbe7

Parents:

4c55a64

Message:

Parts of data reception. Trimming segment to receive window.

File:

• uspace/srv/net/tl/tcp/seq_no.c (modified) (3 diffs)

uspace/srv/net/tl/tcp/seq_no.c

@@ -71 +71 @@
  *
  * ACK is duplicate if it refers to a sequence number that has
- * aleady been acked (SEG.ACK < SND.UNA).
+ * aleady been acked (SEG.ACK <= SND.UNA).
  */
 bool seq_no_ack_duplicate(tcp_conn_t *conn, uint32_t seg_ack)
@@ -81 +81 @@
          * equivalent of SEG.ACK < SND.UNA. Thus we do it
          * on a best-effort basis, based on the difference.
-         * [-2^31, 0) means less-than, [0, 2^31) means greater-than.
+         * [-2^31, 0) means less-than, 0 means equal, [0, 2^31)
+         * means greater-than. Less-than or equal means duplicate.
          */
         diff = seg_ack - conn->snd_una;
-        return (diff & (0x1 << 31)) != 0;
+        return diff == 0 || (diff & (0x1 << 31)) != 0;
 }
 
@@ -176 +177 @@
 }
 
+/** Calculate the amount of trim needed to fit segment in receive window. */
+extern void seq_no_seg_trim_calc(tcp_conn_t *conn, tcp_segment_t *seg,
+    uint32_t *left, uint32_t *right)
+{
+        assert(seq_no_segment_acceptable(conn, seg));
+
+        /*
+         * If RCV.NXT is between SEG.SEQ and RCV.NXT+RCV.WND, then
+         * left trim amount is positive
+         */
+        if (seq_no_lt_le(seg->seq, conn->rcv_nxt,
+            conn->rcv_nxt + conn->rcv_wnd)) {
+                *left = conn->rcv_nxt - seg->seq;
+        } else {
+                *left = 0;
+        }
+
+        /*
+         * If SEG.SEQ+SEG.LEN is between SEG.SEQ and RCV.NXT+RCV.WND,
+         * then right trim is zero.
+         */
+        if (seq_no_lt_le(seg->seq - 1, seg->seq + seg->len,
+            conn->rcv_nxt + conn->rcv_wnd)) {
+                *right = 0;
+        } else {
+                *right = (seg->seq + seg->len) -
+                    (conn->rcv_nxt + conn->rcv_wnd);
+        }
+}
+
 /**
  * @}