Merge pull request #1 from enlyze/fix/worst-case

Handle the worst case of 1-byte requests at 115200 baud.

src/driver/EnlyzePortSniffer.h

@@ -1,6 +1,6 @@
 //
 // PortSniffer - Monitor the traffic of arbitrary serial or parallel ports
-// Copyright 2020 Colin Finck, ENLYZE GmbH <[email protected]>
+// Copyright 2020-2021 Colin Finck, ENLYZE GmbH <[email protected]>
 //
 // SPDX-License-Identifier: MIT
 //
@@ -16,9 +16,15 @@
 
 #define CONTROL_DEVICE_NAME_STRING L"\\Device\\EnlyzePortSniffer"
 #define CONTROL_SYMBOLIC_LINK_NAME_STRING L"\\DosDevices\\EnlyzePortSniffer"
-#define MAX_LOG_ENTRIES_PER_PORT 32
 #define POOL_TAG (ULONG)'nSoP'
 
+// The worst case is a serial port at 115200 baud, which is read via 1-byte requests.
+// 115200 baud makes 14400 bytes/second. Considering that the PortSniffer-Tool polls the
+// driver in 10 millisecond intervals (100 times/second), we need to buffer up to
+// 144 1-byte log entries.
+// Choose 160 (divisible by 32) as the upper limit here to be on the safe side.
+#define MAX_LOG_ENTRIES_PER_PORT 160
+
 
 typedef struct _PORTLOG_ENTRY
 {

src/tool/monitoring.c

@@ -1,6 +1,6 @@
 //
 // PortSniffer - Monitor the traffic of arbitrary serial or parallel ports
-// Copyright 2020 Colin Finck, ENLYZE GmbH <[email protected]>
+// Copyright 2020-2021 Colin Finck, ENLYZE GmbH <[email protected]>
 //
 // SPDX-License-Identifier: MIT
 //
@@ -138,7 +138,16 @@ HandleMonitorParameter(
  &cbReturned,
  NULL))
  {
- fprintf(stderr, "DeviceIoControl failed for PORTSNIFFER_IOCTL_CONTROL_RESET_PORT_MONITORING, last error is %lu.\n", GetLastError());
+ if (GetLastError() == ERROR_FILE_NOT_FOUND)
+ {
+ fprintf(stderr, "The PortSniffer Driver is not attached to %S!\n", pwszPort);
+ fprintf(stderr, "Please run this tool using the /attach option.\n");
+ }
+ else
+ {
+ fprintf(stderr, "DeviceIoControl failed for PORTSNIFFER_IOCTL_CONTROL_RESET_PORT_MONITORING, last error is %lu.\n", GetLastError());
+ }
+
  goto Cleanup;
  }
 
@@ -154,8 +163,6 @@ HandleMonitorParameter(
  // Fetch new port log entries from our driver until we are terminated.
  while (!_bTerminationRequested)
  {
- Sleep(250);
-
  if (!DeviceIoControl(hPortSniffer,
  (DWORD)PORTSNIFFER_IOCTL_CONTROL_POP_PORTLOG_ENTRY,
  &PopRequest,
@@ -167,12 +174,14 @@ HandleMonitorParameter(
  {
  if (GetLastError() == ERROR_NO_MORE_ITEMS)
  {
+ Sleep(10);
  continue;
  }
  else if (GetLastError() == ERROR_FILE_NOT_FOUND)
  {
- fprintf(stderr, "The PortSniffer Driver is not attached to %S!\n", pwszPort);
+ fprintf(stderr, "The PortSniffer Driver is no longer attached to %S!\n", pwszPort);
  fprintf(stderr, "Please run this tool using the /attach option.\n");
+ goto Cleanup;
  }
  else
  {