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.