lookupHostsReader

fn lookupHostsReader(
    t: *Threaded,
    host_name: HostName,
    resolved: *Io.Queue(HostName.LookupResult),
    options: HostName.LookupOptions,
    reader: *Io.Reader,
) error{ ReadFailed, Canceled, UnknownHostName, Closed }!void {
    const t_io = io(t);
    var addresses_len: usize = 0;
    var canonical_name: ?HostName = null;
    while (true) {
        const line = reader.takeDelimiterExclusive('\n') catch |err| switch (err) {
            error.StreamTooLong => {
                // Skip lines that are too long.
                _ = reader.discardDelimiterInclusive('\n') catch |er| switch (er) {
                    error.EndOfStream => break,
                    error.ReadFailed => |e| return e,
                };
                continue;
            },
            error.ReadFailed => |e| return e,
            error.EndOfStream => break,
        };
        reader.toss(@min(1, reader.bufferedLen()));
        var split_it = std.mem.splitScalar(u8, if (is_windows and std.mem.endsWith(u8, line, "\r"))
            line[0 .. line.len - 1]
        else
            line, '#');
        const no_comment_line = split_it.first();

        var line_it = std.mem.tokenizeAny(u8, no_comment_line, " \t");
        const ip_text = line_it.next() orelse continue;
        var first_name_text: ?[]const u8 = null;
        while (line_it.next()) |name_text| {
            if (std.ascii.eqlIgnoreCase(name_text, host_name.bytes)) {
                if (first_name_text == null) first_name_text = name_text;
                break;
            }
        } else continue;

        if (canonical_name == null) {
            if (options.canonical_name_buffer) |buf| {
                if (HostName.init(first_name_text.?)) |name_text| {
                    if (name_text.bytes.len <= buf.len) {
                        const canonical_name_dest = buf[0..name_text.bytes.len];
                        @memcpy(canonical_name_dest, name_text.bytes);
                        canonical_name = .{ .bytes = canonical_name_dest };
                    }
                } else |_| {}
            }
        }

        if (options.family != .ip6) {
            if (IpAddress.parseIp4(ip_text, options.port)) |addr| {
                try resolved.putOne(t_io, .{ .address = addr });
                addresses_len += 1;
            } else |_| {}
        }
        if (options.family != .ip4) {
            if (IpAddress.parseIp6(ip_text, options.port)) |addr| {
                try resolved.putOne(t_io, .{ .address = addr });
                addresses_len += 1;
            } else |_| {}
        }
    }

    if (canonical_name) |canon_name| try resolved.putOne(t_io, .{ .canonical_name = canon_name });
    if (addresses_len == 0) return error.UnknownHostName;
}