| JavaTM 2 Platform Std. Ed. v1.4.2
java.net
Class SocketPermission
java.lang.Object
 java.security.Permission
java.net.SocketPermission
- All Implemented Interfaces:
- Guard, Serializable
- public final class SocketPermission
- extends Permission
- implements Serializable
This class represents access to a network via sockets.
A SocketPermission consists of a
host specification and a set of "actions" specifying ways to
connect to that host. The host is specified as
host = (hostname | IPv4address | iPv6reference) [:portrange]
portrange = portnumber | -portnumber | portnumber-[portnumber]
The host is expressed as a DNS name, as a numerical IP address,
or as "localhost" (for the local machine).
The wildcard "*" may be included once in a DNS name host
specification. If it is included, it must be in the leftmost
position, as in "*.sun.com".
The format of the IPv6reference should follow that specified in RFC 2732: Format
for Literal IPv6 Addresses in URLs:
ipv6reference = "[" IPv6address "]"
For example, you can construct a SocketPermission instance
as the following:
String hostAddress = inetaddress.getHostAddress();
if (inetaddress instanceof Inet6Address) {
sp = new SocketPermission("[" + hostAddress + "]:" + port, action);
} else {
sp = new SocketPermission(hostAddress + ":" + port, action);
}
or
String host = url.getHost();
sp = new SocketPermission(host + ":" + port, action);
The full uncompressed form of
an IPv6 literal address is also valid.
The port or portrange is optional. A port specification of the
form "N-", where N is a port number, signifies all ports
numbered N and above, while a specification of the
form "-N" indicates all ports numbered N and below.
The possible ways to connect to the host are
accept
connect
listen
resolve
The "listen" action is only meaningful when used with "localhost".
The "resolve" action is implied when any of the other actions are present.
The action "resolve" refers to host/ip name service lookups.
As an example of the creation and meaning of SocketPermissions,
note that if the following permission:
p1 = new SocketPermission("puffin.eng.sun.com:7777", "connect,accept");
is granted to some code, it allows that code to connect to port 7777 on
puffin.eng.sun.com, and to accept connections on that port.
Similarly, if the following permission:
p1 = new SocketPermission("puffin.eng.sun.com:7777", "connect,accept");
p2 = new SocketPermission("localhost:1024-", "accept,connect,listen");
is granted to some code, it allows that code to
accept connections on, connect to, or listen on any port between
1024 and 65535 on the local host.
Note: Granting code permission to accept or make connections to remote
hosts may be dangerous because malevolent code can then more easily
transfer and share confidential data among parties who may not
otherwise have access to the data.
- See Also:
Permissions,
SocketPermission
SocketPermission
public SocketPermission(String host,
String action)
- Creates a new SocketPermission object with the specified actions.
The host is expressed as a DNS name, or as a numerical IP address.
Optionally, a port or a portrange may be supplied (separated
from the DNS name or IP address by a colon).
To specify the local machine, use "localhost" as the host.
Also note: An empty host String ("") is equivalent to "localhost".
The actions parameter contains a comma-separated list of the
actions granted for the specified host (and port(s)). Possible actions are
"connect", "listen", "accept", "resolve", or
any combination of those. "resolve" is automatically added
when any of the other three are specified.
Examples of SocketPermission instantiation are the following:
nr = new SocketPermission("www.catalog.com", "connect");
nr = new SocketPermission("www.sun.com:80", "connect");
nr = new SocketPermission("*.sun.com", "connect");
nr = new SocketPermission("*.edu", "resolve");
nr = new SocketPermission("204.160.241.0", "connect");
nr = new SocketPermission("localhost:1024-65535", "listen");
nr = new SocketPermission("204.160.241.0:1024-65535", "connect");
- Parameters:
host - the hostname or IPaddress of the computer, optionally
including a colon followed by a port or port range.action - the action string.
implies
public boolean implies(Permission p)
- Checks if this socket permission object "implies" the
specified permission.
More specifically, this method first ensures that all of the following
are true (and returns false if any of them are not):
- p is an instanceof SocketPermission,
- p's actions are a proper subset of this
object's actions, and
- p's port range is included in this port range. Note:
port range is ignored when p only contains the action, 'resolve'.
Then implies checks each of the following, in order,
and for each returns true if the stated condition is true:
- If this object was initialized with a single IP address and one of p's
IP addresses is equal to this object's IP address.
- If this object is a wildcard domain (such as *.sun.com), and
p's canonical name (the name without any preceding *)
ends with this object's canonical host name. For example, *.sun.com
implies *.eng.sun.com..
- If this object was not initialized with a single IP address, and one of this
object's IP addresses equals one of p's IP addresses.
- If this canonical name equals p's canonical name.
If none of the above are true, implies returns false.
- Specified by:
implies in class Permission
- Parameters:
p - the permission to check against.
- Returns:
- true if the specified permission is implied by this object,
false if not.
equals
public boolean equals(Object obj)
- Checks two SocketPermission objects for equality.
- Specified by:
equals in class Permission
- Parameters:
obj - the object to test for equality with this object.
- Returns:
- true if obj is a SocketPermission, and has the
same hostname, port range, and actions as this
SocketPermission object. However, port range will be ignored
in the comparison if obj only contains the action, 'resolve'.
hashCode
public int hashCode()
- Returns the hash code value for this object.
- Specified by:
hashCode in class Permission
- Returns:
- a hash code value for this object.
getActions
public String getActions()
- Returns the canonical string representation of the actions.
Always returns present actions in the following order:
connect, listen, accept, resolve.
- Specified by:
getActions in class Permission
- Returns:
- the canonical string representation of the actions.
newPermissionCollection
public PermissionCollection newPermissionCollection()
- Returns a new PermissionCollection object for storing SocketPermission
objects.
SocketPermission objects must be stored in a manner that allows them
to be inserted into the collection in any order, but that also enables the
PermissionCollection implies
method to be implemented in an efficient (and consistent) manner.
- Overrides:
newPermissionCollection in class Permission
- Returns:
- a new PermissionCollection object suitable for storing SocketPermissions.
Copyright 2003 Sun Microsystems, Inc. All rights reserved
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