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 resolveThe "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.
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");
SecurityManager.checkPermission method is called,
passing this permission object as the permission to check.
Returns silently if access is granted. Otherwise, throws
a SecurityException.java.io.FilePermission,
the name will be a pathname.More specifically, this method first ensures that all of the following are true (and returns false if any of them are not):
implies checks each of the following, in order,
and for each returns true if the stated condition is true:
implies returns false.
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.
wait methods.
The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
synchronized statement
that synchronizes on the object.
Class, by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
wait methods.
The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify method or the
notifyAll method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait();
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.The current thread must own this object's monitor.
This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:
A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout);
... // Perform action appropriate to condition
}
(For more information on this topic, see Section 3.2.3 in Doug Lea's
"Concurrent Programming in Java (Second Edition)" (Addison-Wesley,
2000), or Item 50 in Joshua Bloch's "Effective Java Programming
Language Guide" (Addison-Wesley, 2001).
If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.
Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is similar to the wait method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:
notify method
or the notifyAll method.
timeout
milliseconds plus nanos nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout, nanos);
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.