gdbrpc 0.5.0

A Python RPC framework for controlling GDB remotely - enables programmatic debugging automation, remote command execution, and interactive CLI for any GDB-compatible debugger

gdbrpc

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A Python-based RPC (Remote Procedure Call) framework for GDB (GNU Debugger) that enables programmatic control and automation of debugging sessions.

Table of Contents

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• gdbrpc
  • Overview
  • Features
  • Installation
    • From PyPI
    • From Source
  • Requirements
  • Quick Start
    • Starting the GDB Server
    • Using the Python Client
    • Using the Interactive CLI
  • TODO
  • Architecture
    • Components
    • Communication Flow
  • API Reference
    • Client
    • Request Classes
  • Configuration
    • Server Configuration
    • Client Configuration
  • Troubleshooting
  • Contributing
  • License
  • Related Projects
  • Support

Overview

gdbrpc provides a client-server architecture that allows you to control GDB instances remotely through a simple Python API. It's designed to be framework-agnostic and can be used with any GDB-compatible debugger, not limited to any specific operating system or embedded platform.

Features

• Remote GDB Control: Execute GDB commands remotely via socket communication
• Bidirectional Communication: Client-server architecture with full duplex support
• Command Serialization: Uses cloudpickle for robust serialization of Python objects
• Interactive CLI: Built-in command-line interface for quick debugging sessions
• Extensible: Easy to integrate into custom debugging workflows and automation scripts

Installation

From PyPI

pip install gdbrpc

From Source

cd gdbrpc
pip install -e .

Requirements

• Python >= 3.10
• GDB with Python support
• cloudpickle >= 0.0.0

Quick Start

Starting the GDB Server

Within a GDB session, use the GDB commands (after importing gdbrpc):

(gdb) py import gdbrpc
(gdb) gdbrpc start
(gdb) gdbrpc start --port 20820 --host 0.0.0.0
(gdb) gdbrpc status
(gdb) gdbrpc stop

Using the Python Client

from gdbrpc import Client
from gdbrpc.utils import ShellExec

# Create and connect to the GDB server
client = Client(host="localhost", port=20819)
client.connect()

# Execute GDB commands
response = client.call(ShellExec("info threads"))
print(response)

# Get backtrace
bt = client.call(ShellExec("backtrace"))
print(bt)

# Evaluate expressions
result = client.call(ShellExec("print my_variable"))
print(result)

# Execute shell commands (prefix with !)
output = client.call(ShellExec("!ls -la"))
print(output)

# Close connection
client.disconnect()

Using the Interactive CLI

The easiest way to interact with a GDB server is using the built-in CLI:

# Connect to default server (localhost:20819)
python3 -m gdbrpc

# Connect to custom host and port
python3 -m gdbrpc --host 192.168.1.100 --port 20820

# Show help
python3 -m gdbrpc --help

Once connected, you can type GDB commands directly:

Welcome to the GDB Remote Protocol Client
Type `exit` or `quit` to disconnect.
Type `help` to show this help message.
If you need `interrupt` command to stop the target, use Ctrl+C.
gdb> info threads
  Id   Target Id                                Frame
* 1    process 1234 "myprogram"                 main () at main.c:42
gdb> backtrace
#0  main () at main.c:42
#1  0x00007ffff7a05b97 in __libc_start_main ()
gdb> print my_variable
$1 = 123
gdb> !ls
file1.txt  file2.txt  myprogram
gdb> exit

Or use the CLI programmatically from Python:

from gdbrpc import ClientCLI

cli = ClientCLI(host="localhost", port=20819)
cli.start()

CLI Features:

• Execute any GDB command interactively
• Run shell commands with ! prefix (e.g., !ls, !pwd)
• Use Ctrl+C to send interrupt signal to target

TODO

• make the CLI provide the same experience as the gdb CLI
  • auto-completion
  • command history reading
• improve network transmission
  • improving security during deserialization

Architecture

Components

• Server: Runs inside GDB process, listens for incoming connections
• Client: Python client that connects to the server and sends commands
• CLI: Interactive command-line interface built on top of the client
• Protocol: Custom protocol for request/response communication using cloudpickle

Communication Flow

┌─────────────┐         Socket         ┌─────────────┐
│   Client    │◄──────────────────────►│   Server    │
│  (Python)   │    (Port 20819)        │  (In GDB)   │
└─────────────┘                        └─────────────┘
      │                                       │
      │ Send Request                          │
      │──────────────────────────────────────►│
      │                                       │ Execute Command
      │                                       │ in GDB Context
      │                            Response   │
      │◄──────────────────────────────────────│
      │                                       │

API Reference

Client

Client(host="localhost", port=20819, logLevel=logging.INFO)

Create a new client instance.

Parameters:

• host (str): Server hostname or IP address (default: "localhost")
• port (int): Server port number (default: 20819)
• logLevel (int): Logging level (default: logging.INFO)

connect() -> bool

Establish connection to the GDB server.

Returns: True if connection successful, False otherwise

call(request: Request, post_request: Optional[PostRequest] = None, timeout: float = 300) -> Any

Send a request to the GDB server and receive response.

Parameters:

• request (Request): Request object to send (typically ShellExec for executing commands)
• post_request (Optional[PostRequest]): Optional callback request for async handling
• timeout (float): Request timeout in seconds (default: 300)

Returns: Response payload from the server

Example:

from gdbrpc import Client
from gdbrpc.utils import ShellExec

client = Client("localhost", 20819)
client.connect()

# Execute GDB command
result = client.call(ShellExec("info threads"))
print(result)

# Execute shell command (prefix with !)
result = client.call(ShellExec("!ls -la"))
print(result)

disconnect()

Close the connection to the server and cleanup resources.

Request Classes

ShellExec(command: str)

Request to execute a GDB command or shell command on the server.

Parameters:

• command (str): Command to execute
  • GDB commands: "info threads", "backtrace", "print variable"
  • Shell commands: prefix with ! or shell, e.g., "!ls" or "shell pwd"

Example:

from gdbrpc.utils import ShellExec

# GDB command
gdb_request = ShellExec("backtrace full")

# Shell command
shell_request = ShellExec("!cat /proc/meminfo")

Request

Base class for all request types. Custom requests can be created by subclassing.

Methods:

• __init__(): Initializes request with unique tag ID
• __call__(*args, **kwargs): Must be implemented by subclasses

PostRequest

Base class for requests with callbacks. Used for asynchronous request handling.

Methods:

• __init__(): Initializes with finish event
• __call__(argument: Any): Must be implemented by subclasses
• finish (threading.Event): Event to signal completion

Configuration

Server Configuration

The server can be configured when starting:

import logging
import gdbrpc

# Start with debug logging
gdbrpc.start_gdb_socket_server(
    host="0.0.0.0",  # Listen on all interfaces
    port=20819,
    logLevel=logging.DEBUG
)

Client Configuration

import logging
from gdbrpc import Client
from gdbrpc.utils import ShellExec

# Create client with custom log level
client = Client(
    host="localhost",
    port=20819,
    logLevel=logging.DEBUG  # Enable debug logging
)
client.connect()

# Custom timeout for specific requests
result = client.call(
    ShellExec("interrupt"),
    timeout=60  # Wait up to 60 seconds for this command
)

Troubleshooting

Server won't start

• Ensure GDB has Python support: gdb --configuration | grep python
• Check if port is already in use: netstat -an | grep 20819
• Verify firewall settings allow the connection

Connection refused

• Verify server is running: (gdb) gdbrpc status
• Check host/port configuration matches between client and server
• Ensure network connectivity between client and server

Command execution fails

• Verify GDB is in correct state (e.g., program loaded, running)
• Check command syntax is correct for your GDB version
• Review server logs for detailed error messages
• Make sure python version GDB uses is same as client

Contributing

Contributions are welcome! Please feel free to submit pull requests or open issues for bugs and feature requests.

License

Licensed under the Apache License, Version 2.0. See the LICENSE file for details.

Related Projects

• GDB Python API Documentation
• pwndbg - GDB plugin for exploit development
• gdb-dashboard - Modular GDB dashboard

Support

For questions and support:

• Open an issue on the project repository
• Consult the GDB Python API documentation
• Review the examples in the examples/ directory

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[!NOTE] While gdbrpc was originally developed as part of the NuttX RTOS debugging tools, it is a standalone, general-purpose library that can be used with any GDB debugging session.