eronnen · neitsa · Feb 13, 2023 · Feb 13, 2023 · Feb 13, 2023 · Feb 14, 2023
diff --git a/docs/StackTraceSymbolicResolution.md b/docs/StackTraceSymbolicResolution.md
@@ -0,0 +1,283 @@
+# Resolving Stack Traces With `procmon-parser`
+
+## Limitations and Constraints
+
+Symbolic stack trace resolution has the following limitations:
+
+* It is based on Windows libraries, thus it is only available on **Windows** systems.
+* It requires an Internet connection.
+* It connects and download files from a Microsoft Server.
+  - By doing so, it requires you to accept Microsoft License terms. 
+
+## Basics 
+
+All events in a ProcMon trace have a [stack trace](https://en.wikipedia.org/wiki/Stack_trace). 
+
+Below is an example of an event in a ProcMon capture:
+
+![Event](./pictures/event.png)
+
+The event captured is a thread creation in `explorer.exe`.
+
+If you double-click the event, you are brought to a new window with 3 tabs, the interesting one in our case being the 
+stack trace tab. Below is an example of the aforementioned event with an **unresolved** stack trace:
+
+![Stack Trace No Symbols](./pictures/stack_trace_no_symbols.png)
+
+And the same event with a **resolved** stack trace:
+
+![Stack Trace No Symbols](./pictures/stack_trace_with_symbols.png)
+
+In the above pictures, after symbolic resolution of the addresses, the latter were resolved to their function names and 
+offsets and sometimes the source code position where the call happens (frames 12 and 13).
+
+Stack Traces are composed of frames (there are 25 frames in the above example), and is read from bottom to top: the 
+oldest call happens at the bottom and goes to the top, traversing all the frames in-between. Once the top function 
+returns, all the frames are unstacked and eventually the code flow goes back to the first frame (at the bottom).
+
+## Resolving a Stack Trace with `procmon-parser`
+
+Resolving a stack trace in `procmon-parser` can be as simple as follows:
+
+```python
+#!/usr/bin/env python3
+# -*- coding:utf-8 -*-
+import pathlib
+import sys
+
+from procmon_parser import ProcmonLogsReader, SymbolResolver, StackTraceInformation
+
+def main():
+    log_file = pathlib.Path(r"c:\temp\Logfile.PML")
+
+    with log_file.open("rb") as f:
+        procmon_reader = ProcmonLogsReader(f)
+        symbol_resolver = SymbolResolver(procmon_reader)
+        for idx, event in enumerate(procmon_reader):
+            if idx == 213:
+                frames = list(symbol_resolver.resolve_stack_trace(event))
+                print(StackTraceInformation.prettify(frames))
+
+if __name__ == "__main__":
+    sys.exit(main())
+```
+
+## Setting Up Stack Trace Resolution In `procmon-parser`
+
+### Obtaining Required Windows Libraries
+
+Stack trace resolution uses 2 Windows DLLs:
+
+* `dbghelp.dll` ([official documentation](https://learn.microsoft.com/en-us/windows/win32/debug/debug-help-library))
+    - Provide symbol resolution functionalities. 
+* `symsrv.dll` ([official documentation](https://learn.microsoft.com/en-us/windows/win32/debug/using-symsrv))
+    - Symbol file management (mostly downloading symbolic information from a symbol store).
+
+While `dbghelp.dll` is provided with Windows systems (it's located in `%WINDIR%\system32`) this DLL might be out of date
+on some systems and thus missing various functionalities (as [explained here](https://learn.microsoft.com/en-us/windows/win32/debug/dbghelp-versions)). 
+`symsrv.dll`, on the other hand, does not ship with Windows systems.
+
+Both DLLs can be acquired from various Microsoft products, notably:
+
+* [Debugging Tools for Windows](https://learn.microsoft.com/en-us/windows-hardware/drivers/debugger/)
+* [Windbg Preview](https://apps.microsoft.com/store/detail/windbg-preview/9PGJGD53TN86)
+* [Visual Studio](https://visualstudio.microsoft.com/downloads/)
+
+The official and [**recommended way**](https://learn.microsoft.com/en-us/windows/win32/debug/dbghelp-versions) is to 
+install the `Debugging Tools For Windows` from the Windows SDK (please note that the SDK installer allows to only 
+install the *Debugging Tools for Windows* and not the whole SDK).
+
+**Important**: `procmon-parser` will try to find the correct path to the Debugging Tools For Windows and Windbg Preview
+and then automatically provide the path to the DLLs matching the Python interpreter architecture. It does not, however, 
+try to find the DLLs from a Visual Studio installation.
+
+Be sure to use the DLLs that matches your interpreter architecture. For example, the *Debugging Tools For Windows* comes
+with 4 different architectures: x86, x64, arm(32) and arm64:
+
+```
+neitsa@lab:c/Program Files (x86)/Windows Kits/10/Debuggers$ tree -L 1
+.
+├── Redist
+├── arm
+├── arm64
+├── ddk
+├── inc
+├── lib
+├── x64
+└── x86
+```
+
+You can get your Python interpreter architecture by using the `platform` module for example:
+
+```
+>>> import platform
+>>> platform.architecture()
+('64bit', 'WindowsPE')
+```
+
+Thus, the directory in the *Debugging Tools For Windows* would be the `x64` one since the Python interpreter is a 64-bit
+one.
+
+### Symsrv and Microsoft License Terms
+
+Microsoft's symbol servers (located at https://msdl.microsoft.com/download/symbols/), provides access to 
+symbols for the operating system itself. The `symsrv.dll` library requires agreement to Microsoft's 
+*"Terms of Use for Microsoft Symbols and Binaries."* ([visible here](https://learn.microsoft.com/en-us/legal/windows-sdk/microsoft-symbol-server-license-terms)).
+
+On your first usage of the symbolic resolution, the `symsrv.dll` may display a prompt requiring you to accept the 
+aforementioned *Terms of Use* if you wish to continue further. 
+
+To automatically indicate agreement to the terms, you may create a file called `symsrv.yes` (there's no need to put 
+something in the file) in the same directory as the `symsrv.dll` library (Note that `symsrv.dll` will also recognize a 
+`symsrv.no` file as indicating that you do not accept the terms; the `.yes` file takes priority over the `.no` file.).  
+
+It is also possible to view the terms from within the WinDbg debugger (included in the *Debugging Tools for Windows*)
+by removing any `symsrv.yes` and `symsrv.no` files from WinDbg's directory, setting the symbol path to include 
+Microsoft's symbol server (using the `.sympath` command), and attempting to load symbols from their server (`.reload` 
+command).
+
+## Advanced Usage
+
+### Symbol Download Location
+
+The [_NT_SYMBOL_PATH](https://learn.microsoft.com/en-us/windows/win32/debug/using-symsrv#setting-the-symbol-path)
+environment variable is the official way to set the location where the symbols are going to be stored.
+
+Symbols files may need to be downloaded from a symbol store, in which case the following algorithm takes place in the
+`SymbolResolver` class:
+
+* if `_NT_SYMBOL_PATH` environment variable is set:
+    - Use `_NT_SYMBOL_PATH` location to put symbol files.
+    - if `symbol_path` constructor argument is set:
+      - Do not use `_NT_SYMBOL_PATH` but use the provided symbol path instead.
+* else
+  - Use `%TEMP%` directory.
+
+Note that using the `%TEMP%` directory may require to download the symbol between each computer reboot. The is most of
+the time a lengthy operation, even with a fast internet connection.
+
+The basic syntax of the `_NT_SYMBOL_PATH` environment variable (and therefore the `symbol_path` constructor argument) is
+as follows:
+
+```
+srv*<symbol_directory>*https://msdl.microsoft.com/download/symbols/
+```
+
+Where `<symbol_directory>` must be an **existing directory** which is **writable** by any user. For example:
+
+```
+srv*c:\symbols*https://msdl.microsoft.com/download/symbols/
+```
+
+For more information on the various possibilities for setting up the environment variable, please refer to the 
+[official documentation](https://learn.microsoft.com/en-us/windows/win32/debug/using-symsrv). 
+
+### Copying DLLs
+
+If, for any reason, you do not wish to install the *Debugging Tools For Windows* on a particular machine (e.g. a virtual
+machine) but already have it installed on another machine you can copy and paste both DLLs (`dbghelp.dll` and 
+`symsrv.dll`) from the *Debugging Tools For Windows* onto the target machine, preferably in their own (writable) 
+directory but **not** a system one (never erase the default one in `%WINDIR%\System32`). Both DLLs must reside alongside each other.
+
+In case you would want to provide a different path for the DLLs, you can use the `dll_dir_path` parameter of the 
+`SymbolResolver` class:
+
+```python
+#!/usr/bin/env python3
+# -*- coding:utf-8 -*-
+import pathlib
+import sys
+
+from procmon_parser import ProcmonLogsReader, SymbolResolver
+
+def main():
+    log_file = pathlib.Path(r"c:\temp\Logfile.PML")
+    dll_dir_path = r"c:\tmp\my_debug_dll_dir"
+
+    with log_file.open("rb") as f:
+        procmon_reader = ProcmonLogsReader(f)
+        # disable automatic retrieval of dbghelp.dll and symsrv.dll, and use the provided path instead.
+        # It must contain at least both DLLs:
+        #     - from the same provider (e.g. Debugging tools for Windows)
+        #     - and the same architecture (e.g. Debugging tools for Windows '\x64' directory).
+        symbol_resolver = SymbolResolver(procmon_reader, dll_dir_path=dll_dir_path)
+        # ...
+
+if __name__ == "__main__":
+    sys.exit(main())
+```
+
+### Skipping `symsrv.dll` Check
+
+The `SymbolResolver` class in `procmon-parser` checks if both `dbghelp` and `symsrv` DLLs are present in the provided 
+directory (if you pass it through the `dll_dir_path` parameter as explained above).
+
+If you have offline symbols already available (for example, by having previously used the `symchk` 
+([documentation](https://learn.microsoft.com/en-us/windows-hardware/drivers/debugger/using-symchk)) tool from the 
+*Debugging Tools For Windows*), and do not want to connect your machine to the Internet, you can skip the `symsrv.dll` 
+automatic check by using the `skip_symsrv` parameter of the `SymbolResolver` class:
+
+```python
+#!/usr/bin/env python3
+# -*- coding:utf-8 -*-
+import pathlib
+import sys
+
+from procmon_parser import ProcmonLogsReader, SymbolResolver
+
+def main():
+    log_file = pathlib.Path(r"c:\temp\Logfile.PML")
+    # does not contain symsrv.dll
+    dll_dir_path = r"c:\tmp\my_debug_dll_dir"  
+
+    with log_file.open("rb") as f:
+        procmon_reader = ProcmonLogsReader(f)
+        # disable automatic retrieval of dbghelp.dll and symsrv.dll, and use the provided path instead.
+        # skip entirely the check for symsrv.dll.
+        # Use **only** if you know that you already have the necessary symbols! 
+        symbol_resolver = SymbolResolver(procmon_reader, dll_dir_path=dll_dir_path, skip_symsrv=True)
+        # ...
+
+if __name__ == "__main__":
+    sys.exit(main())
+```
+
+## Debugging Symbol Resolution Problem
+
+If symbol resolution is not working as expected, you can pass a callback function - using the `debug_callback` named 
+parameter - to the `SymbolResolver` constructor, as follows:
+
+```python
+#!/usr/bin/env python3
+# -*- coding:utf-8 -*-
+import pathlib
+import sys
+
+from procmon_parser import ProcmonLogsReader, SymbolResolver, CBA
+
+def symbol_debug_callback(handle: int, action_code: CBA | int, callback_data: str, user_context: int):
+    if action_code == CBA.CBA_DEBUG_INFO:
+        print(f"[DEBUG MESSAGE DBGHELP: CBA_DEBUG_INFO] {callback_data}")
+        return 1
+    return 0
+
+def main():
+    log_file = pathlib.Path(r"c:\temp\Logfile.PML")
+
+    with log_file.open("rb") as f:
+        procmon_reader = ProcmonLogsReader(f)
+        symbol_resolver = SymbolResolver(procmon_reader, debug_callback=symbol_debug_callback)
+        # ...
+
+if __name__ == "__main__":
+    sys.exit(main())
+```
+
+The callback function mimics the [PSYMBOL_REGISTERED_CALLBACK64 ](https://learn.microsoft.com/en-us/windows/win32/api/dbghelp/nc-dbghelp-psymbol_registered_callback64)
+Windows' API callback function. As of now only the `CBA.CBA_DEBUG_INFO` action code is handled internally.
+
+To indicate success handling the `CBA` code, the function **must** return 1. To indicate failure handling the code, 
+return 0. If your code does not handle a particular code, you should also return 0. (Returning 1 in this case may have 
+unintended consequences.)
+
+This will print a lot of information that is helpful debugging symbol retrieval problems.
diff --git a/docs/pictures/event.png b/docs/pictures/event.png
diff --git a/docs/pictures/stack_trace_no_symbols.png b/docs/pictures/stack_trace_no_symbols.png
diff --git a/docs/pictures/stack_trace_with_symbols.png b/docs/pictures/stack_trace_with_symbols.png
diff --git a/procmon_parser/__init__.py b/procmon_parser/__init__.py
@@ -1,3 +1,5 @@
+import sys
+
 from six import PY2
 
 from procmon_parser.configuration import *
@@ -11,6 +13,12 @@
     'Rule', 'Column', 'RuleAction', 'RuleRelation', 'PMLError'
 ]
 
+if sys.platform == "win32" and sys.version_info >= (3, 5, 0):
+    from procmon_parser.symbol_resolver.symbol_resolver import (
+        SymbolResolver, StackTraceFrameInformation, StackTraceInformation, CBA)
+
+    __all__.extend(['SymbolResolver', 'StackTraceFrameInformation', 'StackTraceInformation', 'CBA'])
+
 
 class ProcmonLogsReader(object):
     """Reads procmon logs from a stream which in the PML format
@@ -44,6 +52,12 @@ def __getitem__(self, index):
     def __len__(self):
         return self._struct_readear.number_of_events
 
+    @property
+    def maximum_application_address(self):
+        """Return the highest possible user land address.
+        """
+        return self._struct_readear.maximum_application_address
+
     def processes(self):
         """Return a list of all the known processes in the log file
         """

diff --git a/procmon_parser/logs.py b/procmon_parser/logs.py
@@ -309,6 +309,12 @@ def get_event_at_offset(self, offset):
     def number_of_events(self):
         return self.header.number_of_events
 
+    @property
+    def maximum_application_address(self):
+        """Return the highest possible user land address.
+        """
+        return self.header.maximum_application_address
+
     def processes(self):
         """Return a list of all the known processes in the log file
         """

diff --git a/procmon_parser/stream_logs_format.py b/procmon_parser/stream_logs_format.py
@@ -36,7 +36,9 @@ def __init__(self, io):
         # Docs of this table's layout are in "docs\PML Format.md"
         self.icon_table_offset = read_u64(stream)
 
-        stream.seek(12, 1)  # Unknown fields
+        self.maximum_application_address = read_u64(stream)
+
+        self.os_version_info_size = read_u32(stream)
         self.windows_major_number = read_u32(stream)
         self.windows_minor_number = read_u32(stream)
         self.windows_build_number = read_u32(stream)

diff --git a/procmon_parser/symbol_resolver/__init__.py b/procmon_parser/symbol_resolver/__init__.py