CHUNKING: fix transmit with long headers

When the buffer used for SMTP commands and message headers filled to flush
point, protocol sequencing was wrong.

19 files changed, 244 insertions, 13 deletions

diff --git a/src/src/smtp_out.c b/src/src/smtp_out.c
index 76181b5f1..5ab15cb5f 100644
--- a/src/src/smtp_out.c
+++ b/src/src/smtp_out.c
@@ -324,14 +324,16 @@ static BOOL
 flush_buffer(smtp_outblock *outblock)
 {
 int rc;
+int n = outblock->ptr - outblock->buffer;
 
+HDEBUG(D_transport|D_acl) debug_printf("cmd buf flush %d bytes\n", n);
 #ifdef SUPPORT_TLS
 if (tls_out.active == outblock->sock)
-  rc = tls_write(FALSE, outblock->buffer, outblock->ptr - outblock->buffer);
+  rc = tls_write(FALSE, outblock->buffer, n);
 else
 #endif
+  rc = send(outblock->sock, outblock->buffer, n, 0);
 
-rc = send(outblock->sock, outblock->buffer, outblock->ptr - outblock->buffer, 0);
 if (rc <= 0)
   {
   HDEBUG(D_transport|D_acl) debug_printf("send failed: %s\n", strerror(errno));
diff --git a/src/src/structs.h b/src/src/structs.h
index ffbc899a5..23c40ea3d 100644
--- a/src/src/structs.h
+++ b/src/src/structs.h
@@ -226,8 +226,7 @@ typedef struct transport_info {
 /* smtp transport datachunk callback */
 
 #define tc_reap_prev	BIT(0)	/* Flags: reap previous SMTP cmd responses */
-#define tc_reap_one	BIT(1)	/* reap one SMTP response */
-#define tc_chunk_last	BIT(2)	/* annotate chunk SMTP cmd as LAST */
+#define tc_chunk_last	BIT(1)	/* annotate chunk SMTP cmd as LAST */
 
 struct transport_context;
 typedef int (*tpt_chunk_cmd_cb)(int fd, struct transport_context * tctx,
diff --git a/src/src/transport.c b/src/src/transport.c
index a68c22f29..fdd97822a 100644
--- a/src/src/transport.c
+++ b/src/src/transport.c
@@ -418,15 +418,22 @@ for (ptr = start; ptr < end; ptr++)
 
   if ((len = chunk_ptr - deliver_out_buffer) > mlen)
     {
+    DEBUG(D_transport) debug_printf("flushing headers buffer\n");
+
     /* If CHUNKING, prefix with BDAT (size) NON-LAST.  Also, reap responses
     from previous SMTP commands. */
 
     if (tctx &&  tctx->options & topt_use_bdat  &&  tctx->chunk_cb)
-      if (tctx->chunk_cb(fd, tctx, (unsigned)len, tc_reap_prev|tc_reap_one) != OK)
+      {
+      if (  tctx->chunk_cb(fd, tctx, (unsigned)len, 0) != OK
+	 || !transport_write_block(fd, deliver_out_buffer, len)
+	 || tctx->chunk_cb(fd, tctx, 0, tc_reap_prev) != OK
+	 )
+	return FALSE;
+      }
+    else
+      if (!transport_write_block(fd, deliver_out_buffer, len))
 	return FALSE;
-
-    if (!transport_write_block(fd, deliver_out_buffer, len))
-      return FALSE;
     chunk_ptr = deliver_out_buffer;
     }
 
@@ -922,11 +929,11 @@ if (!(tctx->options & topt_no_headers))
     return FALSE;
   }
 
-/* When doing RFC3030 CHUNKING output, work out how much data will be in the
-last BDAT, consisting of the current write_chunk() output buffer fill
+/* When doing RFC3030 CHUNKING output, work out how much data would be in a
+last-BDAT, consisting of the current write_chunk() output buffer fill
 (optimally, all of the headers - but it does not matter if we already had to
 flush that buffer with non-last BDAT prependix) plus the amount of body data
-(as expanded for CRLF lines).  Then create and write the BDAT, and ensure
+(as expanded for CRLF lines).  Then create and write BDAT(s), and ensure
 that further use of write_chunk() will not prepend BDATs.
 The first BDAT written will also first flush any outstanding MAIL and RCPT
 commands which were buffered thans to PIPELINING.
@@ -960,6 +967,8 @@ if (tctx->options & topt_use_bdat)
 
   if (size > DELIVER_OUT_BUFFER_SIZE && hsize > 0)
     {
+    DEBUG(D_transport)
+      debug_printf("sending small initial BDAT; hssize=%d\n", hsize);
     if (  tctx->chunk_cb(fd, tctx, hsize, 0) != OK
        || !transport_write_block(fd, deliver_out_buffer, hsize)
        || tctx->chunk_cb(fd, tctx, 0, tc_reap_prev) != OK
diff --git a/src/src/transports/smtp.c b/src/src/transports/smtp.c
index 52b2b913f..416ea6297 100644
--- a/src/src/transports/smtp.c
+++ b/src/src/transports/smtp.c
@@ -1402,6 +1402,8 @@ if (tctx->pending_BDAT)
 
 if (flags & tc_reap_prev  &&  prev_cmd_count > 0)
   {
+  DEBUG(D_transport) debug_printf("look for %d responses"
+    " for previous pipelined cmds\n", prev_cmd_count);
 
   switch(sync_responses(tctx->first_addr, tctx->tblock->rcpt_include_affixes,
 	  tctx->sync_addr, tctx->host, prev_cmd_count,
@@ -1424,10 +1426,12 @@ if (flags & tc_reap_prev  &&  prev_cmd_count > 0)
     pipelining_active = FALSE;
   }
 
-/* Reap response for the cmd we just emitted, or an outstanding BDAT */
+/* Reap response for an outstanding BDAT */
 
-if (flags & tc_reap_one  ||  tctx->pending_BDAT)
+if (tctx->pending_BDAT)
   {
+  DEBUG(D_transport) debug_printf("look for one response for BDAT\n");
+
   if (!smtp_read_response(tctx->inblock, buffer, DELIVER_BUFFER_SIZE, '2',
        ob->command_timeout))
     {
diff --git a/test/log/0902 b/test/log/0902
index 63e180185..24eb7a951 100644
--- a/test/log/0902
+++ b/test/log/0902
@@ -29,3 +29,6 @@
 1999-03-02 09:44:33 10HmbE-0005vi-00 ** v@test.ex R=to_server T=remote_smtp H=127.0.0.1 [127.0.0.1]: SMTP error from remote mail server after end of data: 500 oops bdat
 1999-03-02 09:44:33 10HmbE-0005vi-00 v@test.ex: error ignored
 1999-03-02 09:44:33 10HmbE-0005vi-00 Completed
+1999-03-02 09:44:33 10HmbF-0005vi-00 <= CALLER@the.local.host.name U=CALLER P=local S=sss for p@test.ex
+1999-03-02 09:44:33 10HmbF-0005vi-00 => p@test.ex R=to_server T=remote_smtp H=127.0.0.1 [127.0.0.1] K C="250 OK bdat"
+1999-03-02 09:44:33 10HmbF-0005vi-00 Completed
diff --git a/test/scripts/0000-Basic/0902 b/test/scripts/0000-Basic/0902
index a1c4de4e1..9c719e1d1 100644
--- a/test/scripts/0000-Basic/0902
+++ b/test/scripts/0000-Basic/0902
@@ -921,5 +921,125 @@ Subject: foo
 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
 ****
 #
+# message with long headers
+server PORT_S
+220 Greetings
+EHLO
+250-Hello there
+250-PIPELINING
+250 CHUNKING
+MAIL FROM
+RCPT TO
+BDAT 8191
+250 OK mail
+250 OK rcpt
+*data 8191
+250 OK nonlast bdat
+BDAT 829 LAST
+*data 829
+250 OK bdat
+QUIT
+225 OK
+*eof
+****
+exim -odf p@test.ex
+Subject: foo
+X-long_hdr: 0
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 2
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 3
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 4
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 5
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 6
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 7
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 8
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+ 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+
+body
+1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890
+****
+#
 #
 no_msglog_check
diff --git a/test/stderr/0143 b/test/stderr/0143
index e0fe9dc93..06370ba40 100644
--- a/test/stderr/0143
+++ b/test/stderr/0143
@@ -20,16 +20,20 @@ delivering 10HmaX-0005vi-00 to 127.0.0.1 [127.0.0.1] (userx@domain.com)
 Connecting to 127.0.0.1 [127.0.0.1]:1224 from ip4.ip4.ip4.ip4 ... connected
   SMTP<< 220 ESMTP
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-OK
          250-HELP
          250 AUTH LOGIN
 not using PIPELINING
 not using DSN
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex>
+cmd buf flush 37 bytes
   SMTP<< 250 Sender OK
   SMTP>> RCPT TO:<userx@domain.com>
+cmd buf flush 28 bytes
   SMTP<< 250 Recipient OK
   SMTP>> DATA
+cmd buf flush 6 bytes
   SMTP<< 354 Send data
   SMTP>> writing message and terminating "."
 writing data block fd=dddd size=sss timeout=300
@@ -39,6 +43,7 @@ transport_check_waiting entered
   sequence=1 local_max=500 global_max=-1
 no messages waiting for 127.0.0.1
   SMTP>> QUIT
+cmd buf flush 6 bytes
   SMTP(close)>>
 Leaving my_smtp transport
 LOG: MAIN
diff --git a/test/stderr/0388 b/test/stderr/0388
index d45a21121..e8269e035 100644
--- a/test/stderr/0388
+++ b/test/stderr/0388
@@ -85,16 +85,20 @@ Connecting to 127.0.0.1 [127.0.0.1]:1224 ... connected
   SMTP<< 220 Server ready
 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250 OK
 127.0.0.1 in hosts_require_auth? no (option unset)
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex>
+cmd buf flush 37 bytes
   SMTP<< 250 OK
   SMTP>> RCPT TO:<x@y>
+cmd buf flush 15 bytes
   SMTP<< 451 Temporary error
 LOG: MAIN
   H=127.0.0.1 [127.0.0.1]: SMTP error from remote mail server after RCPT TO:<x@y>: 451 Temporary error
 added retry item for R:x@y: errno=-44 more_errno=dd,A flags=0
   SMTP>> QUIT
+cmd buf flush 6 bytes
   SMTP(close)>>
 set_process_info: pppp delivering 10HmaX-0005vi-00: just tried 127.0.0.1 [127.0.0.1] for x@y: result OK
 address match test: subject=*@127.0.0.1 pattern=*
diff --git a/test/stderr/0398 b/test/stderr/0398
index 0a4d1fe23..c11dd6f86 100644
--- a/test/stderr/0398
+++ b/test/stderr/0398
@@ -130,13 +130,17 @@ Connecting to 127.0.0.1 [127.0.0.1]:1224 ... connected
   SMTP<< 220 Server ready
 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
   SMTP>> EHLO mail.test.ex
+cmd buf flush 19 bytes
   SMTP<< 250 OK
 127.0.0.1 in hosts_require_auth? no (option unset)
   SMTP>> MAIL FROM:<>
+cmd buf flush 14 bytes
   SMTP<< 250 OK
   SMTP>> RCPT TO:<qq@remote>
+cmd buf flush 21 bytes
   SMTP<< 550 Unknown
   SMTP>> QUIT
+cmd buf flush 6 bytes
 locking TESTSUITE/spool/db/callout.lockfile
 locked TESTSUITE/spool/db/callout.lockfile
 EXIM_DBOPEN(TESTSUITE/spool/db/callout)
diff --git a/test/stderr/0404 b/test/stderr/0404
index f1c32cf94..e8746d9c5 100644
--- a/test/stderr/0404
+++ b/test/stderr/0404
@@ -17998,6 +17998,7 @@ lock file created
 mailbox TESTSUITE/test-mail/sender is locked
 writing to file TESTSUITE/test-mail/sender
 writing data block fd=dddd size=sss timeout=0
+flushing headers buffer
 writing data block fd=dddd size=sss timeout=0
 writing data block fd=dddd size=sss timeout=0
 writing data block fd=dddd size=sss timeout=0
diff --git a/test/stderr/0432 b/test/stderr/0432
index 95a24a9eb..54b9593bd 100644
--- a/test/stderr/0432
+++ b/test/stderr/0432
@@ -91,13 +91,17 @@ Connecting to 127.0.0.1 [127.0.0.1]:1224 ... connected
   SMTP<< 220 server ready
 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250 OK
 127.0.0.1 in hosts_require_auth? no (option unset)
   SMTP>> MAIL FROM:<>
+cmd buf flush 14 bytes
   SMTP<< 250 OK
   SMTP>> RCPT TO:<x@y>
+cmd buf flush 15 bytes
   SMTP<< 250 OK
   SMTP>> QUIT
+cmd buf flush 6 bytes
 locking TESTSUITE/spool/db/callout.lockfile
 locked TESTSUITE/spool/db/callout.lockfile
 EXIM_DBOPEN(TESTSUITE/spool/db/callout)
@@ -247,13 +251,17 @@ MUNGED: ::1 will be omitted in what follows
 >>>   SMTP<< 220 server ready
 >>> 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
 >>>   SMTP>> EHLO myhost.test.ex
+>>> cmd buf flush 21 bytes
 >>>   SMTP<< 250 OK
 >>> 127.0.0.1 in hosts_require_auth? no (option unset)
 >>>   SMTP>> MAIL FROM:<>
+>>> cmd buf flush 14 bytes
 >>>   SMTP<< 250 OK
 >>>   SMTP>> RCPT TO:<a@b>
+>>> cmd buf flush 15 bytes
 >>>   SMTP<< 250 OK
 >>>   SMTP>> QUIT
+>>> cmd buf flush 6 bytes
 >>> wrote callout cache domain record for b:
 >>>   result=1 postmaster=0 random=0
 >>> wrote positive callout cache address record for a@b
@@ -287,6 +295,7 @@ MUNGED: ::1 will be omitted in what follows
 >>>   SMTP<< 220 server ready
 >>> 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
 >>>   SMTP>> EHLO myhost.test.ex
+>>> cmd buf flush 21 bytes
 >>> SMTP timeout
 >>> ----------- end verify ------------
 >>> accept: condition test deferred in ACL "mail"
diff --git a/test/stderr/0476 b/test/stderr/0476
index 29b9c3ebb..695557676 100644
--- a/test/stderr/0476
+++ b/test/stderr/0476
@@ -19,6 +19,7 @@ set_process_info: pppp delivering 10HmaX-0005vi-00 to 127.0.0.1 [127.0.0.1] (use
 Connecting to 127.0.0.1 [127.0.0.1]:1224 ... connected
   SMTP<< 220 Server ready
   SMTP>> EHLO the.local.host.name
+cmd buf flush 18 bytes
   SMTP<< 250-server id
          250-PIPELINING
          250 OK
@@ -27,6 +28,7 @@ not using DSN
   SMTP>> MAIL FROM:<CALLER@the.local.host.name>
   SMTP>> RCPT TO:<userx@test.ex>
   SMTP>> DATA
+cmd buf flush 65 bytes
   SMTP<< 250 OK
   SMTP<< 550 NO
 Remote host closed connection in response to pipelined DATA
@@ -35,6 +37,7 @@ ok=1 send_quit=1 send_rset=1 continue_more=0 yield=0 first_address is NULL
 transport_check_waiting entered
   sequence=1 local_max=500 global_max=-1
   SMTP>> RSET
+cmd buf flush 6 bytes
 H=127.0.0.1 [127.0.0.1] Remote host closed connection in response to RSET
   SMTP(close)>>
 set_process_info: pppp delivering 10HmaX-0005vi-00: just tried 127.0.0.1 [127.0.0.1] for userx@test.ex: result OK
diff --git a/test/stderr/2013 b/test/stderr/2013
index 11e165c61..459f75027 100644
--- a/test/stderr/2013
+++ b/test/stderr/2013
@@ -6,6 +6,7 @@ LOG: queue_run MAIN
 Connecting to 127.0.0.1 [127.0.0.1]:1225 ... connected
   SMTP<< 220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello localhost [127.0.0.1]
          250-SIZE 52428800
          250-8BITMIME
@@ -13,8 +14,10 @@ Connecting to 127.0.0.1 [127.0.0.1]:1225 ... connected
          250-STARTTLS
          250 HELP
   SMTP>> STARTTLS
+cmd buf flush 10 bytes
   SMTP<< 220 TLS go ahead
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello localhost [127.0.0.1]
          250-SIZE 52428800
          250-8BITMIME
@@ -23,11 +26,13 @@ Connecting to 127.0.0.1 [127.0.0.1]:1225 ... connected
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex> SIZE=ssss
   SMTP>> RCPT TO:<userx@test.ex>
   SMTP>> DATA
+cmd buf flush 78 bytes
   SMTP<< 250 OK
   SMTP<< 250 Accepted
   SMTP<< 354 Enter message, ending with "." on a line by itself
   SMTP<< 250 OK id=10HmaZ-0005vi-00
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello localhost [127.0.0.1]
          250-SIZE 52428800
          250-8BITMIME
@@ -44,8 +49,10 @@ configuration file is TESTSUITE/test-config
 trusted user
 admin user
   SMTP>> STARTTLS
+cmd buf flush 10 bytes
   SMTP<< 220 TLS go ahead
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello localhost [127.0.0.1]
          250-SIZE 52428800
          250-8BITMIME
@@ -54,11 +61,13 @@ admin user
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex> SIZE=ssss
   SMTP>> RCPT TO:<userx@test.ex>
   SMTP>> DATA
+cmd buf flush 78 bytes
   SMTP<< 250 OK
   SMTP<< 250 Accepted
   SMTP<< 354 Enter message, ending with "." on a line by itself
   SMTP<< 250 OK id=10HmbA-0005vi-00
   SMTP>> QUIT
+cmd buf flush 6 bytes
   SMTP(close)>>
 LOG: MAIN
   => userx@test.ex R=client T=send_to_server H=127.0.0.1 [127.0.0.1]* X=TLS1.x:xxxxRSA_AES_256_CBC_SHAnnn:256 CV=no DN="C=UK,O=The Exim Maintainers,OU=Test Suite,CN=Phil Pennock" C="250 OK id=10HmbA-0005vi-00"
diff --git a/test/stderr/2113 b/test/stderr/2113
index ec5e415c6..1ea573043 100644
--- a/test/stderr/2113
+++ b/test/stderr/2113
@@ -6,6 +6,7 @@ LOG: queue_run MAIN
 Connecting to 127.0.0.1 [127.0.0.1]:1225 ... connected
   SMTP<< 220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello localhost [127.0.0.1]
          250-SIZE 52428800
          250-8BITMIME
@@ -13,8 +14,10 @@ Connecting to 127.0.0.1 [127.0.0.1]:1225 ... connected
          250-STARTTLS
          250 HELP
   SMTP>> STARTTLS
+cmd buf flush 10 bytes
   SMTP<< 220 TLS go ahead
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello localhost [127.0.0.1]
          250-SIZE 52428800
          250-8BITMIME
@@ -23,11 +26,13 @@ Connecting to 127.0.0.1 [127.0.0.1]:1225 ... connected
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex> SIZE=ssss
   SMTP>> RCPT TO:<userx@test.ex>
   SMTP>> DATA
+cmd buf flush 78 bytes
   SMTP<< 250 OK
   SMTP<< 250 Accepted
   SMTP<< 354 Enter message, ending with "." on a line by itself
   SMTP<< 250 OK id=10HmaZ-0005vi-00
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello localhost [127.0.0.1]
          250-SIZE 52428800
          250-8BITMIME
@@ -44,8 +49,10 @@ configuration file is TESTSUITE/test-config
 trusted user
 admin user
   SMTP>> STARTTLS
+cmd buf flush 10 bytes
   SMTP<< 220 TLS go ahead
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello localhost [127.0.0.1]
          250-SIZE 52428800
          250-8BITMIME
@@ -54,11 +61,13 @@ admin user
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex> SIZE=ssss
   SMTP>> RCPT TO:<userx@test.ex>
   SMTP>> DATA
+cmd buf flush 78 bytes
   SMTP<< 250 OK
   SMTP<< 250 Accepted
   SMTP<< 354 Enter message, ending with "." on a line by itself
   SMTP<< 250 OK id=10HmbA-0005vi-00
   SMTP>> QUIT
+cmd buf flush 6 bytes
   SMTP(close)>>
 LOG: MAIN
   => userx@test.ex R=client T=send_to_server H=127.0.0.1 [127.0.0.1]* X=TLSv1:AES256-SHA:256 CV=no DN="/C=UK/O=The Exim Maintainers/OU=Test Suite/CN=Phil Pennock" C="250 OK id=10HmbA-0005vi-00"
diff --git a/test/stderr/5403 b/test/stderr/5403
index 292f09133..b91e254f3 100644
--- a/test/stderr/5403
+++ b/test/stderr/5403
@@ -73,11 +73,14 @@ MUNGED: ::1 will be omitted in what follows
 >>>   SMTP<< 220 server ready
 >>> 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
 >>>   SMTP>> EHLO myhost.test.ex
+>>> cmd buf flush 21 bytes
 >>>   SMTP<< 250 OK
 >>> 127.0.0.1 in hosts_require_auth? no (option unset)
 >>>   SMTP>> MAIL FROM:<CALLER@myhost.test.ex>
+>>> cmd buf flush 37 bytes
 >>>   SMTP<< 250 OK
 >>>   SMTP>> RCPT TO:<verify@domain.com>
+>>> cmd buf flush 29 bytes
 >>>   SMTP<< 250 OK
 >>> holding verify callout open for cutthrough delivery
 >>> ----------- end verify ------------
diff --git a/test/stderr/5410 b/test/stderr/5410
index fe3ed4429..e305e6a90 100644
--- a/test/stderr/5410
+++ b/test/stderr/5410
@@ -56,6 +56,7 @@ considering: $primary_hostname
   SMTP<< 220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
          250-SIZE 52428800
          250-8BITMIME
@@ -101,12 +102,14 @@ considering: :}}
      result: :
 127.0.0.1 in hosts_verify_avoid_tls? no (end of list)
   SMTP>> STARTTLS
+cmd buf flush 10 bytes
   SMTP<< 220 TLS go ahead
 127.0.0.1 in hosts_require_ocsp? no (option unset)
 127.0.0.1 in hosts_request_ocsp? yes (matched "*")
 127.0.0.1 in tls_verify_hosts? no (option unset)
 127.0.0.1 in tls_try_verify_hosts? no (end of list)
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
          250-SIZE 52428800
          250-8BITMIME
@@ -114,8 +117,10 @@ considering: :}}
          250 HELP
 127.0.0.1 in hosts_require_auth? no (option unset)
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex>
+cmd buf flush 37 bytes
   SMTP<< 250 OK
   SMTP>> RCPT TO:<userx@domain.com>
+cmd buf flush 28 bytes
   SMTP<< 250 Accepted
 holding verify callout open for cutthrough delivery
 ----------- end cutthrough setup ------------
@@ -314,6 +319,7 @@ considering: $primary_hostname
   SMTP<< 220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
          250-SIZE 52428800
          250-8BITMIME
@@ -341,8 +347,10 @@ considering: *}{:}}
 127.0.0.1 in hosts_avoid_tls? yes (matched "*")
 127.0.0.1 in hosts_require_auth? no (option unset)
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex>
+cmd buf flush 37 bytes
   SMTP<< 250 OK
   SMTP>> RCPT TO:<usery@domain.com>
+cmd buf flush 28 bytes
   SMTP<< 250 Accepted
 holding verify callout open for cutthrough delivery
 ----------- end cutthrough setup ------------
@@ -541,6 +549,7 @@ considering: $primary_hostname
   SMTP<< 220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
          250-SIZE 52428800
          250-8BITMIME
@@ -568,8 +577,10 @@ considering: *}{:}}
 127.0.0.1 in hosts_avoid_tls? yes (matched "*")
 127.0.0.1 in hosts_require_auth? no (option unset)
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex>
+cmd buf flush 37 bytes
   SMTP<< 250 OK
   SMTP>> RCPT TO:<usery@domain.com>
+cmd buf flush 28 bytes
   SMTP<< 250 Accepted
 holding verify callout open for cutthrough delivery
 ----------- end cutthrough setup ------------
diff --git a/test/stderr/5420 b/test/stderr/5420
index 623b99864..ac54a65d6 100644
--- a/test/stderr/5420
+++ b/test/stderr/5420
@@ -56,6 +56,7 @@ considering: $primary_hostname
   SMTP<< 220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
          250-SIZE 52428800
          250-8BITMIME
@@ -101,11 +102,13 @@ considering: :}}
      result: :
 127.0.0.1 in hosts_verify_avoid_tls? no (end of list)
   SMTP>> STARTTLS
+cmd buf flush 10 bytes
   SMTP<< 220 TLS go ahead
 127.0.0.1 in tls_verify_hosts? no (option unset)
 127.0.0.1 in tls_try_verify_hosts? yes (matched "*")
 127.0.0.1 in tls_verify_cert_hostnames? yes (matched "*")
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
          250-SIZE 52428800
          250-8BITMIME
@@ -113,8 +116,10 @@ considering: :}}
          250 HELP
 127.0.0.1 in hosts_require_auth? no (option unset)
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex>
+cmd buf flush 37 bytes
   SMTP<< 250 OK
   SMTP>> RCPT TO:<userx@domain.com>
+cmd buf flush 28 bytes
   SMTP<< 250 Accepted
 holding verify callout open for cutthrough delivery
 ----------- end cutthrough setup ------------
@@ -313,6 +318,7 @@ considering: $primary_hostname
   SMTP<< 220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
          250-SIZE 52428800
          250-8BITMIME
@@ -340,8 +346,10 @@ considering: *}{:}}
 127.0.0.1 in hosts_avoid_tls? yes (matched "*")
 127.0.0.1 in hosts_require_auth? no (option unset)
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex>
+cmd buf flush 37 bytes
   SMTP<< 250 OK
   SMTP>> RCPT TO:<usery@domain.com>
+cmd buf flush 28 bytes
   SMTP<< 250 Accepted
 holding verify callout open for cutthrough delivery
 ----------- end cutthrough setup ------------
@@ -540,6 +548,7 @@ considering: $primary_hostname
   SMTP<< 220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
 127.0.0.1 in hosts_avoid_esmtp? no (option unset)
   SMTP>> EHLO myhost.test.ex
+cmd buf flush 21 bytes
   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
          250-SIZE 52428800
          250-8BITMIME
@@ -567,8 +576,10 @@ considering: *}{:}}
 127.0.0.1 in hosts_avoid_tls? yes (matched "*")
 127.0.0.1 in hosts_require_auth? no (option unset)
   SMTP>> MAIL FROM:<CALLER@myhost.test.ex>
+cmd buf flush 37 bytes
   SMTP<< 250 OK
   SMTP>> RCPT TO:<usery@domain.com>
+cmd buf flush 28 bytes
   SMTP<< 250 Accepted
 holding verify callout open for cutthrough delivery
 ----------- end cutthrough setup ------------
diff --git a/test/stderr/5840 b/test/stderr/5840
index 250e606ca..08712d0d9 100644
--- a/test/stderr/5840
+++ b/test/stderr/5840
@@ -26,6 +26,7 @@ MUNGED: ::1 will be omitted in what follows
 >>>   SMTP<< 220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
 >>> ip4.ip4.ip4.ip4 in hosts_avoid_esmtp? no (option unset)
 >>>   SMTP>> EHLO myhost.test.ex
+>>> cmd buf flush 21 bytes
 >>>   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
 >>>          250-SIZE 52428800
 >>>          250-8BITMIME
@@ -35,11 +36,13 @@ MUNGED: ::1 will be omitted in what follows
 >>> ip4.ip4.ip4.ip4 in hosts_avoid_tls? no (option unset)
 >>> ip4.ip4.ip4.ip4 in hosts_verify_avoid_tls? no (option unset)
 >>>   SMTP>> STARTTLS
+>>> cmd buf flush 10 bytes
 >>>   SMTP<< 220 TLS go ahead
 >>> ip4.ip4.ip4.ip4 in hosts_require_ocsp? no (option unset)
 >>> ip4.ip4.ip4.ip4 in hosts_require_ocsp? no (option unset)
 >>> ip4.ip4.ip4.ip4 in hosts_request_ocsp? no (end of list)
 >>>   SMTP>> EHLO myhost.test.ex
+>>> cmd buf flush 21 bytes
 >>>   SMTP<< 250-myhost.test.ex Hello the.local.host.name [ip4.ip4.ip4.ip4]
 >>>          250-SIZE 52428800
 >>>          250-8BITMIME
@@ -47,10 +50,13 @@ MUNGED: ::1 will be omitted in what follows
 >>>          250 HELP
 >>> ip4.ip4.ip4.ip4 in hosts_require_auth? no (option unset)
 >>>   SMTP>> MAIL FROM:<>
+>>> cmd buf flush 14 bytes
 >>>   SMTP<< 250 OK
 >>>   SMTP>> RCPT TO:<CALLER@dane256ee.test.ex>
+>>> cmd buf flush 38 bytes
 >>>   SMTP<< 250 Accepted
 >>>   SMTP>> QUIT
+>>> cmd buf flush 6 bytes
 >>> wrote callout cache domain record for dane256ee.test.ex:
 >>>   result=1 postmaster=0 random=0
 >>> wrote positive callout cache address record for CALLER@dane256ee.test.ex
diff --git a/test/stdout/0902 b/test/stdout/0902
index 58dba6788..8c5422035 100644
--- a/test/stdout/0902
+++ b/test/stdout/0902
@@ -138,3 +138,22 @@ BDAT 8380 LAST
 QUIT
 225 OK
 End of script
+Listening on port 1224 ... 
+Connection request from [127.0.0.1]
+220 Greetings
+EHLO the.local.host.name
+250-Hello there
+250-PIPELINING
+250 CHUNKING
+MAIL FROM:<>
+RCPT TO:<p@test.ex>
+BDAT 8191
+250 OK mail
+250 OK rcpt
+250 OK nonlast bdat
+BDAT 829 LAST
+250 OK bdat
+QUIT
+225 OK
+Expected EOF read from client
+End of script