Module java.base

Package javax.net.ssl

Class SNIHostName

java.lang.Object

javax.net.ssl.SNIServerName

javax.net.ssl.SNIHostName

public final class SNIHostName
extends SNIServerName

Instances of this class represent a server name of type host_name in a Server Name Indication (SNI) extension.

As described in section 3, "Server Name Indication", of TLS Extensions (RFC 6066), "HostName" contains the fully qualified DNS hostname of the server, as understood by the client. The encoded server name value of a hostname is represented as a byte string using ASCII encoding without a trailing dot. This allows the support of Internationalized Domain Names (IDN) through the use of A-labels (the ASCII-Compatible Encoding (ACE) form of a valid string of Internationalized Domain Names for Applications (IDNA)) defined in RFC 5890.

Note that SNIHostName objects are immutable.

Since:

1.8

See Also:

• SNIServerName
• StandardConstants.SNI_HOST_NAME

Constructor Summary

Constructors

Constructor	Description
SNIHostName(byte[] encoded)	Creates an SNIHostName using the specified encoded value.
SNIHostName(String hostname)	Creates an SNIHostName using the specified hostname.

Method Summary

Modifier and Type	Method	Description
static SNIMatcher	createSNIMatcher(String regex)	Creates an SNIMatcher object for SNIHostNames.
boolean	equals(Object other)	Compares this server name to the specified object.
String	getAsciiName()	Returns the StandardCharsets.US_ASCII-compliant hostname of this SNIHostName object.
int	hashCode()	Returns a hash code value for this SNIHostName.
String	toString()	Returns a string representation of the object, including the DNS hostname in this SNIHostName object.

Methods declared in class javax.net.ssl.SNIServerName

getEncoded, getType

Methods declared in class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Details

SNIHostName

public SNIHostName(String hostname)

Creates an SNIHostName using the specified hostname.

Note that per RFC 6066, the encoded server name value of a hostname is StandardCharsets.US_ASCII-compliant. In this method, hostname can be a user-friendly Internationalized Domain Name (IDN). IDN.toASCII(String, int) is used to enforce the restrictions on ASCII characters in hostnames (see RFC 3490, RFC 1122, RFC 1123) and translate the hostname into ASCII Compatible Encoding (ACE), as:

     IDN.toASCII(hostname, IDN.USE_STD3_ASCII_RULES);
 

The hostname argument is illegal if it:

• hostname is empty,
• hostname ends with a trailing dot,
• hostname is not a valid Internationalized Domain Name (IDN) compliant with the RFC 3490 specification.

Parameters:

hostname - the hostname of this server name

Throws:

NullPointerException - if hostname is null

IllegalArgumentException - if hostname is illegal

SNIHostName

public SNIHostName(byte[] encoded)

Creates an SNIHostName using the specified encoded value.

This method is normally used to parse the encoded name value in a requested SNI extension.

Per RFC 6066, the encoded name value of a hostname is StandardCharsets.US_ASCII-compliant. However, in the previous version of the SNI extension ( RFC 4366), the encoded hostname is represented as a byte string using UTF-8 encoding. For the purpose of version tolerance, this method allows that the charset of encoded argument can be StandardCharsets.UTF_8, as well as StandardCharsets.US_ASCII. IDN.toASCII(String) is used to translate the encoded argument into ASCII Compatible Encoding (ACE) hostname.

It is strongly recommended that this constructor is only used to parse the encoded name value in a requested SNI extension. Otherwise, to comply with RFC 6066, please always use StandardCharsets.US_ASCII-compliant charset and enforce the restrictions on ASCII characters in hostnames (see RFC 3490, RFC 1122, RFC 1123) for encoded argument, or use SNIHostName(String) instead.

The encoded argument is illegal if it:

• encoded is empty,
• encoded ends with a trailing dot,
• encoded is not encoded in StandardCharsets.US_ASCII or StandardCharsets.UTF_8-compliant charset,
• encoded is not a valid Internationalized Domain Name (IDN) compliant with the RFC 3490 specification.

Note that the encoded byte array is cloned to protect against subsequent modification.

Parameters:

encoded - the encoded hostname of this server name

Throws:

NullPointerException - if encoded is null

IllegalArgumentException - if encoded is illegal

Method Details

getAsciiName

public String getAsciiName()

Returns the StandardCharsets.US_ASCII-compliant hostname of this SNIHostName object.

Note that, per RFC 6066, the returned hostname may be an internationalized domain name that contains A-labels. See RFC 5890 for more information about the detailed A-label specification.

Returns:

the StandardCharsets.US_ASCII-compliant hostname of this SNIHostName object

equals

public boolean equals(Object other)

Compares this server name to the specified object.

Per RFC 6066, DNS hostnames are case-insensitive. Two server hostnames are equal if, and only if, they have the same name type, and the hostnames are equal in a case-independent comparison.

Overrides:

equals in class SNIServerName

Parameters:

other - the other server name object to compare with.

Returns:

true if, and only if, the other is considered equal to this instance

See Also:

• Object.hashCode()
• HashMap

hashCode

public int hashCode()

Returns a hash code value for this SNIHostName.

The hash code value is generated using the case-insensitive hostname of this SNIHostName.

Overrides:

hashCode in class SNIServerName

Returns:

a hash code value for this SNIHostName.

See Also:

• Object.equals(java.lang.Object)
• System.identityHashCode(java.lang.Object)

toString

public String toString()

Returns a string representation of the object, including the DNS hostname in this SNIHostName object.

The exact details of the representation are unspecified and subject to change, but the following may be regarded as typical:

     "type=host_name (0), value=<hostname>"
 

The "<hostname>" is an ASCII representation of the hostname, which may contain A-labels. For example, a returned value of a pseudo hostname may look like:

     "type=host_name (0), value=www.example.com"
 

or

     "type=host_name (0), value=xn--fsqu00a.xn--0zwm56d"
 

Please NOTE that the exact details of the representation are unspecified and subject to change.

Overrides:

toString in class SNIServerName

Returns:

a string representation of the object.

createSNIMatcher

public static SNIMatcher createSNIMatcher(String regex)

Creates an SNIMatcher object for SNIHostNames.

This method can be used by a server to verify the acceptable SNIHostNames. For example,

     SNIMatcher matcher =
         SNIHostName.createSNIMatcher("www\\.example\\.com");
 

will accept the hostname "www.example.com".

     SNIMatcher matcher =
         SNIHostName.createSNIMatcher("www\\.example\\.(com|org)");
 

will accept hostnames "www.example.com" and "www.example.org".

Parameters:

regex - the regular expression pattern representing the hostname(s) to match

Returns:

a SNIMatcher object for SNIHostNames

Throws:

NullPointerException - if regex is null

PatternSyntaxException - if the regular expression's syntax is invalid