Socket types define the communication properties that are visible to a user. The Internet family sockets provide access to the TCP/IP transport protocols. The Internet family is identified by the value AF_INET6, for sockets that can communicate over both IPv6 and IPv4. The value AF_INET is also supported for source compatibility with old applications and for “raw” access to IPv4.
The SunOS environment supports three types of sockets:
Stream sockets enable processes to communicate
using TCP. A stream socket provides a bidirectional, reliable, sequenced,
and unduplicated flow of data with no record boundaries. After the connection
has been established, data can be read from and written to these sockets as
a byte stream. The socket type is SOCK_STREAM
.
Datagram sockets enable processes to
use UDP to communicate. A datagram socket supports a bidirectional flow of
messages. A process on a datagram socket can receive messages in a different
order from the sending sequence. A process on a datagram socket can receive
duplicate messages. Record boundaries in the data are preserved. The socket
type is SOCK_DGRAM
.
Raw sockets provide access to ICMP. These
sockets are normally datagram oriented, although their exact characteristics
are dependent on the interface provided by the protocol. Raw sockets are not
for most applications. Raw sockets are provided to support the development
of new communication protocols, or for access to more esoteric facilities
of an existing protocol. Only superuser processes can use raw sockets. The
socket type is SOCK_RAW
.
See Selecting Specific Protocols for further information.