local-etc-hosts-updater/src/util.zig

const std = @import("std");

const ArgError = error{
    NotEnoughArgs,
    BadDomain,
};

pub const IPs = struct {
    v4: [:0]const u8,
    v6: [:0]const u8,
};

pub const Domain = struct {
    name: [:0]const u8,
    labels: u8,
};

pub fn check_perms() !void {
    var f = try std.fs.openFileAbsolute("/etc/hosts", .{ .mode = .write_only });
    f.close();
}

pub fn get_input() !Domain {
    var args = std.process.args();
    _ = args.next();
    const domain = args.next() orelse return ArgError.NotEnoughArgs;
    return check_domain(domain);
}

fn check_domain(domain_str: [:0]const u8) !Domain {
    var domain = Domain{
        .name = domain_str,
        .labels = 0,
    };
    var labels = std.mem.split(u8, domain_str, ".");
    var last: []const u8 = "";
    while (labels.next()) |segment| {
        last = segment;
        domain.labels += 1;
    }
    if (domain.labels <= 1 or !std.mem.eql(u8, last, "local")) {
        return ArgError.BadDomain;
    }
    return domain;
}