internal: send LOCAL_CLEANUP on forward delete

WOLFSSH_FWD_LOCAL_CLEANUP is part of the public WS_FwdCbAction contract
and the library never sent it, so an application's handler never ran and
every peer-opened forward leaked what its setup callback allocated.
ChannelDelete() now sends it, so a peer close, an open refused after the
setup ran, wolfSSH_ChannelFree(), and freeing the session all report it.

- record the setup in a new fwdSetupTxd bit on WOLFSSH_CHANNEL: a
  locally opened forward gets no LOCAL_SETUP, so the channel type alone
  cannot say whether the application holds anything
- clear the bit when the cleanup goes out, so a channel reports it once
- pass the channel's id in the port parameter, the way
  WOLFSSH_FWD_CHANNEL_ID does, so an application with two forwards can
  tell which one ended
- TestDirectTcpipFwdCbRejectsChannelId now counts three callback calls

Author: ejohnstown

src/internal.c

@@ -3834,12 +3834,44 @@ WOLFSSH_CHANNEL* ChannelNew(WOLFSSH* ssh, byte channelType,
 }
 
 
+#ifdef WOLFSSH_FWD
+/* Counterpart of the WOLFSSH_FWD_LOCAL_SETUP sent when a forwarding channel
+ * was opened, so the application can release what it set up there. Gated on
+ * that setup having gone out: a locally opened forward never receives one,
+ * and cleaning up after it would free what it does not own. Runs from
+ * ChannelDelete() so every way a channel goes, a peer close, a refused
+ * open, wolfSSH_ChannelFree(), or the session being freed, reports it once.
+ * The channel's id rides in the port parameter, the way CHANNEL_ID passes
+ * it. */
+static void NotifyFwdLocalCleanup(WOLFSSH_CHANNEL* channel)
+{
+    WOLFSSH* ssh;
+    int ret;
+
+    if (channel == NULL || !channel->fwdSetupTxd)
+        return;
+    ssh = channel->ssh;
+    if (ssh == NULL || ssh->ctx->fwdCb == NULL)
+        return;
+
+    channel->fwdSetupTxd = 0;
+    ret = ssh->ctx->fwdCb(WOLFSSH_FWD_LOCAL_CLEANUP, ssh->fwdCbCtx,
+            NULL, channel->channel);
+    if (ret != WS_SUCCESS) {
+        WLOG(WS_LOG_WARN, "Forward cleanup failed for channel %u, ret = %d",
+                channel->channel, ret);
+    }
+}
+#endif /* WOLFSSH_FWD */
+
+
 void ChannelDelete(WOLFSSH_CHANNEL* channel, void* heap)
 {
     WOLFSSH_UNUSED(heap);
 
     if (channel) {
     #ifdef WOLFSSH_FWD
+        NotifyFwdLocalCleanup(channel);
         if (channel->host)
             WFREE(channel->host, heap, DYNTYPE_STRING);
         if (channel->origin)
@@ -12039,6 +12071,9 @@ static int DoChannelOpen(WOLFSSH* ssh,
                     ret = ssh->ctx->fwdCb(WOLFSSH_FWD_LOCAL_SETUP,
                             ssh->fwdCbCtx, host, hostPort);
                     if (ret == WS_SUCCESS) {
+                        /* The application now owns whatever the setup made,
+                         * so it is owed the matching cleanup. */
+                        newChannel->fwdSetupTxd = 1;
                         ret = ssh->ctx->fwdCb(WOLFSSH_FWD_CHANNEL_ID,
                                 ssh->fwdCbCtx, NULL, newChannel->channel);
                     }

tests/regress.c

@@ -3242,7 +3242,9 @@ static void TestDirectTcpipFwdCbRejectsChannelId(void)
      * unlike the rejections that set the reason themselves. */
     AssertIntEQ(ParseChannelOpenFailReason(harness.io.out, harness.io.outSz),
             OPEN_ADMINISTRATIVELY_PROHIBITED);
-    AssertIntEQ(fwdCbCallCount, 2);
+    /* Three, not two: the setup that succeeded is owed its cleanup even
+     * though the open went on to fail. */
+    AssertIntEQ(fwdCbCallCount, 3);
 
     FreeChannelOpenHarness(&harness);
 }

wolfssh/internal.h

@@ -1375,6 +1375,7 @@ struct WOLFSSH_CHANNEL {
     byte eofTxd : 1;
     byte openConfirmed : 1;
     byte ptyReq : 1; /* flag for if interactive pty request was received */
+    byte fwdSetupTxd : 1; /* a WOLFSSH_FWD_LOCAL_SETUP went out for this one */
     word32 channel;
     word32 windowSz;
     word32 maxPacketSz;