Zencode

Bencode encoder/decoder library written in Zig v0.13
Visit BEP-0003 for more information about Bencode format

Note

This project is work in progress, use at own discretion

Install

# latest release
zig fetch https://github.com/mitander/zencode/archive/v0.2.0.tar.gz --save

# master branch
zig fetch https://github.com/mitander/zencode/archive/master.tar.gz --save

# specific commit
zig fetch https://github.com/mitander/zencode/archive/<COMMIT>.tar.gz --save

build.zig:

const zencode = b.dependency("zencode", .{}).module("zencode");
exe.root_module.addModule("zencode", zencode);

Usage

const std = @import("std");
const zencode = @import("zencode");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const ally = gpa.allocator();
    defer _ = gpa.deinit();

    var file = try std.fs.cwd().openFile("./assets/debian-mac-12.1.0-amd64-netinst.iso.torrent", .{});
    defer file.close();

    // parse bencode to value tree
    const v = try zencode.parseReader(file.reader(), ally);
    defer v.deinit();

    // access map values using zencode.mapLookupOptional(map, key, type)
    // Types: [String, Integer, List, Map]
    // Returns: error if key was not found
    const announce = try zencode.mapLookup(v.root.Map, "announce", .String);
    std.debug.assert(std.mem.eql(u8, announce, "http://bttracker.debian.org:6969/announce"));
    std.debug.print("announce: {s}\n", .{announce});

    // mapLookupOptional returns a optional value instead of error
    if (zencode.mapLookupOptional(v.root.Map, "info", .Map)) |info| {
        const name = zencode.mapLookupOptional(info, "name", .String).?;
        std.debug.assert(std.mem.eql(u8, name, "debian-mac-12.1.0-amd64-netinst.iso"));
        std.debug.print("name: {s}\n", .{name});
    }

    // try to access map value with invalid tag type
    const invalid_tag = zencode.mapLookup(v.root.Map, "info", .Integer);
    const invalid_tag_optional = zencode.mapLookupOptional(v.root.Map, "info", .Integer);
    std.debug.assert(invalid_tag == zencode.ParseError.InvalidMapTag);
    std.debug.assert(invalid_tag_optional == null);

    // try to access non-existing map value
    const not_found = zencode.mapLookup(v.root.Map, "not-found", .String);
    const not_found_optional = zencode.mapLookupOptional(v.root.Map, "not-found", .String);
    std.debug.assert(not_found == zencode.ParseError.MapKeyNotFound);
    std.debug.assert(not_found_optional == null);

    // you can add a custom error to be returned if a map key is not found
    zencode.MapLookupError = error.MyCustomError;
    const custom_not_found = zencode.mapLookup(v.root.Map, "not-found", .Integer);
    std.debug.assert(custom_not_found == error.MyCustomError);
}

Run examples

# decode
zig build example_decode

# encode
zig build example_encode

License

MIT