intro(3n)intro(3n)Nameintro - introduction to network library functions
Description
This section describes functions that are available for interprocess
communication (IPC). IPC takes place using sockets. The system call
creates a communications channel based on domain, type, and protocol.
Sockets are created without names. The system call is used to connect
a name to a socket.
A connection with another process must be made before data can be
transferred on a bound socket. The system call is used to rendezvous
with another process. This process must be listening on a bound socket
using the system call. This listening process can accept a connection
request using the system call.
Once two processes have connected and accepted an IPC, data can be
transferred with the following system calls: and
Connectionless sockets are also possible (a socket is bound and data
can be transferred). They use the following system calls to transfer
data: and
IPC operates in three domains:
UNIX Local node
INTERNET Local area network (LAN)
DECNET DECnet network
These types of sockets are available for IPC:
stream Sequenced, reliable, unduplicated data
CONNECTED socket
record boundaries not preserved
all domains
datagram Not guaranteed to be sequenced, reliable, or
unduplicated
user protocol needed to give guarantees
UNCONNECTED socket
record boundaries preserved
UNIX and INTERNET domains
sequenced packet Like stream socket, except record boundaries preserved
DECNET domain only
raw Access to communications protocols
Internet Addresses Routines
The inet routines manipulate Internet addresses.
Network Data Base File Routines
Standard mapping routines are used to retrieve entries in network data
base files. Several routines operating on each data base file are
identified by a group name:
Retrieves entries from
Retrieves entries from
Retrieves entries from
Retrieves entries from
Specific routines perform particular operations on each data base file:
Reads the next line of the file; opens
the file, if necessary.
Opens and rewinds the file.
Closes the file.
Searches the file sequentially from the beginning
until a matching name is found, or EOF is encountered.
Searches the file sequentially from the beginning
until a matching address is found, or EOF is encoun‐
tered.
Searches the file sequentially from the beginning
until a matching port number is found, or EOF is
encountered.
Searches the file sequentially from the beginning
until a matching protocol number is found, or EOF is
encountered.
Each network library routine returns a pointer to a structure reflect‐
ing individual fields of a line in one of the network data base files.
The structure for each data base file contains some of the fields in
the following list, with the prefix x replaced by a different letter in
each file:
pointer to a network address,
returned in network-byte order
address family of the address being returned
alternate names
length of an address, in bytes
official name
network number, returned in machine-byte order
resident port
protocol number
intro(3n)
