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| 1 | +# CLAUDE.md |
| 2 | + |
| 3 | +This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository. |
| 4 | + |
| 5 | +## Project Overview |
| 6 | + |
| 7 | +This is a **Go FTP server library** (`ftpserver` package) that provides a complete RFC 959-compliant FTP server implementation with TLS, IPv6, and extended command support. The library uses a **driver-based architecture** where users implement interfaces to customize file system operations and authentication. |
| 8 | + |
| 9 | +## Architecture |
| 10 | + |
| 11 | +### Core Driver Pattern |
| 12 | +The library centers around three main interfaces: |
| 13 | +- **MainDriver**: Authentication, client lifecycle, TLS configuration |
| 14 | +- **ClientDriver**: File system operations (based on `afero.Fs`) |
| 15 | +- **ClientContext**: Client connection metadata and context |
| 16 | + |
| 17 | +### Key Components |
| 18 | +- **Server Core** (`server.go`): Main server with command mapping system |
| 19 | +- **Client Handler** (`client_handler.go`): Per-client connection management and protocol state machine |
| 20 | +- **Command Handlers**: Organized by functionality (`handle_*.go` files) |
| 21 | +- **Transfer System**: Separate active (`transfer_active.go`) and passive (`transfer_pasv.go`) mode implementations |
| 22 | + |
| 23 | +## Common Commands |
| 24 | + |
| 25 | +### Development |
| 26 | +```bash |
| 27 | +# Build the library |
| 28 | +go build -v ./... |
| 29 | + |
| 30 | +# Run full test suite with race detection and coverage |
| 31 | +go test -parallel 20 -v -race -coverprofile=coverage.txt -covermode=atomic ./... |
| 32 | + |
| 33 | +# Lint code |
| 34 | +golangci-lint run |
| 35 | +``` |
| 36 | + |
| 37 | +### Testing Specific Components |
| 38 | +```bash |
| 39 | +# Test individual handlers |
| 40 | +go test -v -run TestHandle |
| 41 | + |
| 42 | +# Test transfers specifically |
| 43 | +go test -v -run TestTransfer |
| 44 | + |
| 45 | +# Run benchmarks |
| 46 | +go test -bench=. |
| 47 | +``` |
| 48 | + |
| 49 | +## File Organization |
| 50 | + |
| 51 | +### Command Handler Structure |
| 52 | +- `handle_auth.go`: Authentication commands (USER, PASS, AUTH, PBSZ, PROT) |
| 53 | +- `handle_files.go`: File operations (STOR, RETR, LIST, NLST, MLST, MLSD) |
| 54 | +- `handle_dirs.go`: Directory operations (CWD, CDUP, MKD, RMD, PWD) |
| 55 | +- `handle_misc.go`: System commands (SYST, FEAT, NOOP, QUIT, HELP) |
| 56 | + |
| 57 | +### Core Files |
| 58 | +- `driver.go`: Interface definitions and driver extensions |
| 59 | +- `client_handler.go`: Main protocol implementation and state management |
| 60 | +- `server.go`: Server initialization and command routing |
| 61 | +- `errors.go`: FTP-specific error codes and handling |
| 62 | + |
| 63 | +## Testing Architecture |
| 64 | + |
| 65 | +The test suite uses a **reference driver implementation** (`driver_test.go`) with: |
| 66 | +- Mock file system using `afero.NewBasePathFs` with temp directories |
| 67 | +- Integration tests that simulate real FTP client interactions |
| 68 | +- Comprehensive coverage of all command handlers and transfer modes |
| 69 | +- Race condition testing for concurrent operations |
| 70 | + |
| 71 | +## Key Dependencies |
| 72 | + |
| 73 | +- `github.com/spf13/afero`: File system abstraction for driver implementations |
| 74 | +- `github.com/fclairamb/go-log`: Logging abstraction supporting multiple frameworks |
| 75 | + |
| 76 | +## Code Conventions |
| 77 | + |
| 78 | +- **No global state**: All server instances are isolated |
| 79 | +- **Interface-based design**: Extensive use of optional interfaces for extensibility |
| 80 | +- **Error handling**: Custom FTP error types with appropriate status codes |
| 81 | +- **Concurrency**: Clean goroutine management without sleep/panic patterns |
| 82 | +- **Line length**: 120 characters maximum (enforced by linter) |
| 83 | +- **Function length**: 80 lines maximum (enforced by linter) |
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