src/peer_protocol.zig


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const std = @import("std");

pub const Handshake = struct {
    info_hash: [20]u8,
    peer_id: [20]u8,

    pub fn read(reader: anytype) !Handshake {
        var msg = [_]u8{0} ** 68;
        try reader.readNoEof(&msg);
        if (msg[0] != 19) return error.ProtocolError;
        if (!std.mem.eql(u8, msg[1..20], "BitTorrent protocol")) return error.ProtocolError;
        //if (!std.mem.allEqual(u8, msg[20..28], 0)) return error.ProtocolError;
        var res: Handshake = undefined;
        @memcpy(&res.info_hash, msg[28..48]);
        @memcpy(&res.peer_id, msg[48..68]);
        return res;
    }

    pub fn write(self: Handshake, writer: anytype) !void {
        try writer.writeByte(19);
        try writer.writeAll("BitTorrent protocol");
        try writer.writeByteNTimes(0, 8);
        try writer.writeAll(&self.info_hash);
        try writer.writeAll(&self.peer_id);
    }
};