DecodableVersions: []string{"v1", "mygroup.com/v2_"},
			ServedVersions:    []string{"v1", "mygroup.com/v2_"},
		},
		expectedErr: `[].decodableVersions[1]: Invalid value: "mygroup.com/v2_": version part: a DNS-1035 label must consist of lower case alphanumeric characters or '-', start with an alphabetic character, and end with an alphanumeric character (e.g. 'my-name',  or 'abc-123', regex used for validation is '[a-z]([-a-z0-9]*[a-z0-9])?')`,
	}, {

		},
		{
			name:        "dns1035Label",
			expr:        `format.dns1035Label().validate("contains a space")`,
			expectValue: types.OptionalOf(types.NewStringList(types.DefaultTypeAdapter, []string{`a DNS-1035 label must consist of lower case alphanumeric characters or '-', start with an alphabetic character, and end with an alphanumeric character (e.g. 'my-name',  or 'abc-123', regex used for validation is '[a-z]([-a-z0-9]*[a-z0-9])?')`})),
		},

		if sign {
			return -erx - P/Q
		}
		return erx + P/Q
	}
	if x >= 6 { // inf > |x| >= 6
		if sign {
			return -1
		}
		return 1
	}
	s := 1 / (x * x)
	var R, S float64
	if x < 1/0.35 { // |x| < 1 / 0.35  ~ 2.857143
		R = ra0 + s*(ra1+s*(ra2+s*(ra3+s*(ra4+s*(ra5+s*(ra6+s*ra7))))))
		S = 1 + s*(sa1+s*(sa2+s*(sa3+s*(sa4+s*(sa5+s*(sa6+s*(sa7+s*sa8)))))))
	} else { // |x| >= 1 / 0.35  ~ 2.857143

	return errs
}

const dns1035LabelFmt string = "[a-z]([-a-z0-9]*[a-z0-9])?"
const dns1035LabelErrMsg string = "a DNS-1035 label must consist of lower case alphanumeric characters or '-', start with an alphabetic character, and end with an alphanumeric character"

// DNS1035LabelMaxLength is a label's max length in DNS (RFC 1035)
const DNS1035LabelMaxLength int = 63

var dns1035LabelRegexp = regexp.MustCompile("^" + dns1035LabelFmt + "$")

// See go.dev/issue/67401.
//
//go:linkname isDomainName
func isDomainName(s string) bool {
	// The root domain name is valid. See golang.org/issue/45715.
	if s == "." {
		return true
	}

	// See RFC 1035, RFC 3696.
	// Presentation format has dots before every label except the first, and the
	// terminal empty label is optional here because we assume fully-qualified

   * validation against <a href="http://www.ietf.org/rfc/rfc3490.txt">RFC 3490</a>
   * ("Internationalizing Domain Names in Applications") is skipped, while validation against <a
   * href="http://www.ietf.org/rfc/rfc1035.txt">RFC 1035</a> is relaxed in the following ways:
   *
   * <ul>
   *   <li>Any part containing non-ASCII characters is considered valid.
   *   <li>Underscores ('_') are permitted wherever dashes ('-') are permitted.

   * validation against <a href="http://www.ietf.org/rfc/rfc3490.txt">RFC 3490</a>
   * ("Internationalizing Domain Names in Applications") is skipped, while validation against <a
   * href="http://www.ietf.org/rfc/rfc1035.txt">RFC 1035</a> is relaxed in the following ways:
   *
   * <ul>
   *   <li>Any part containing non-ASCII characters is considered valid.
   *   <li>Underscores ('_') are permitted wherever dashes ('-') are permitted.

		}
	}
	return allErrs
}

const dns1035LabelFmt string = "[a-z]([-a-z0-9]*[a-z0-9])?"
const dns1035LabelErrMsg string = "a DNS-1035 label, which must consist of lower case alphanumeric characters or '-', start with an alphabetic character, and end with an alphanumeric character"

// isValidAPIVersion tests whether the value passed is a valid apiVersion. A

	compressionOff := len(b)
	msg := h.pack(b)

	// RFC 1035 allows (but does not require) compression for packing. RFC
	// 1035 requires unpacking implementations to support compression, so
	// unconditionally enabling it is fine.
	//
	// DNS lookups are typically done over UDP, and RFC 1035 states that UDP
	// DNS messages can be a maximum of 512 bytes long. Without compression,

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// DNS client: see RFC 1035.
// Has to be linked into package net for Dial.

// TODO(rsc):
//	Could potentially handle many outstanding lookups faster.
//	Random UDP source port (net.Dial should do that for us).
//	Random request IDs.

package net

import (
	"context"
	"errors"