command_parser

An educational example of a command parser for CLI applications, written in modern C++23. Demonstrates clean and efficient command parsing, using up-to-date C++ features and best practices. Ideal for learning how to build robust CLI tools in C++.

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Features

• Hash text or files using MD5, SHA1, or SHA256
• Verify hashes for files or text against expected values
• Short, UNIX-style CLI flags: -h, -t, -f, -o, -v, -e
• Secure, modern C++23 code with strong error handling
• Refuses duplicate or unknown arguments
• Safe file handling: only user-owned, non-symlinked files can be hashed/verified

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Build

Requirements:

• C++23 compiler (GCC 13+, Clang 16+, MSVC 2022+)
• OpenSSL (dev package, e.g. libssl-dev on Linux)
• CMake 3.20+

Build steps:

git clone https://github.com/mavirique/command_parser.git
cd command_parser
mkdir build && cd build
cmake ..
cmake --build .

Usage

 # Hash text
command_parser -h <algo> -t <text>

 # Hash file
command_parser -h <algo> -f <file>

 # Hash text, write output
command_parser -h <algo> -t <text> -o <out>

 # Hash file, write output
command_parser -h <algo> -f <file> -o <out>

 # Verify text
command_parser -v -h <algo> -t <text> -e <hash>

 # Verify file
command_parser -v -h <algo> -f <file> -e <hash>

# Show usage
command_parser --help
command_parser -H

Flags

-h <algo> Hash algorithm: md5, sha1, sha256
-t <text> Text to hash
-f <file> File to hash
-o <out> Output file (optional, for hash command)
-v Verification mode
-e <hash> Expected hash (required for verification)
--help Show usage
-H Show usage

Only one of -t or -f may be specified per command. Duplicate or unknown flags are rejected with an error. Output: Prints hash/OK/FAIL to stdout, or writes to file with -o.

Examples

Hash a file:

command_parser -h sha256 -f myfile.txt

Hash text and write to file:

command_parser -h md5 -t "hello world" -o hash.txt

Verify a file’s hash:

./command_parser -v -h sha256 -f sample.txt -e 7f83b1657ff1fc53b92dc18148a1d65dfc2d4b1fa3d677284addd200126d9069

Security Notes

Refuses to hash or verify files not owned by the user.

Refuses to hash or verify symlinked files.

All command-line arguments are validated and parsed safely using modern C++23 practices.

Development & Contributing

Code is modern C++23 and clang-tidy clean.

Pull requests for more algorithms, CLI improvements, or security reviews are welcome!

To test or audit, see the source for unit-testable logic in cli_parse.cpp and hash_util.cpp.

License

MIT
Built by cybersecurity enthusiasts, for cybersecurity practitioners.