Linux shell implementation of socket programming simple example

When it comes to sockets, people who have learned the basics of internet have heard that he is the abstraction of TCP/IP, he is the portal of the Internet world, it is everywhere.

Learn the socket programming, means to be able to more deep control of your traffic, and then look at the Python urllib* or php curl, it is pediatrics!

I. Some nouns

Address Family

Address type, protocol family, may be the following

Socket.af_inet---> IPv4 addresses.
SOCKET.AF_INET6---> IPV6 addresses.
Socket.af_unix---> UNIX domain sockets (for example,/var/run/mysqld/mysqld.sock is a example).
SOCKET.AF_IPX---> IPX addresses.
Socktype

Sock type

Socket. Sock_stream---> Streaming sockets, for TCP
Socket. SOCK_DGRAM---> Datagram sockets, for UDP

Other

Parameters	Take value	Value	Description
Address Family	Af_inet	2	IPv4
	Af_inet6	23	IPv6
	Af_unspec	0	Protocol irrelevant
Protocol Numbers Protocol Number	Ipproto_ip	0	IP protocol
	Ipproto_ipv4	4	IPv4
	Ipproto_ipv6	41	IPv6
	Ipproto_udp	17	Udp
	Ipproto_tcp	6	Tcp
Socktype sock Type	Sock_stream	1	Flow
	Sock_dgram	2	Data Report
Ai_flags	Ai_passive	1	Passive, used for bind, typically used for server sockets
	Ai_canonname	2	The canonical name used to return the host
	Ai_numerichost	4	Address is a number string

Ii. Simple Examples

Examples from official documents are very basic.

Service side

# Echo Server Program
Import socket

HOST = ' 127.0.0.1 ' # symbolic name meaning all available interfaces
Port = 50007 # arbitrary non-privileged Port
s = socket.socket (socket.af_inet, socket. SOCK_STREAM)
S.bind (HOST, PORT)
S.listen (1)
conn, addr = S.accept ()
print ' Connected by ', addr
While 1:
data = CONN.RECV (1024)
If not data:break
Conn.sendall (data)
Conn.close ()
Client

# Echo Client program
Import socket

host = ' localhost ' # The remote host
Port = 50007 # The same port as used by the server
s = socket.socket (socket.af_inet, socket. SOCK_STREAM)
S.connect (HOST, PORT)
S.sendall (' Hello, World ')
data = S.RECV (1024)
S.close ()
print ' Received ', repr (data)

Iii. more complex examples

Service side

Unlike before, support for IPV6

# Echo Server Program
Import socket
Import Sys

HOST = None # symbolic name meaning all available interfaces
Port = 50007 # arbitrary non-privileged Port
s = None
For res in Socket.getaddrinfo (HOST, PORT, Socket.af_unspec,
Socket. Sock_stream, 0, socket. ai_passive):
AF, Socktype, Proto, canonname, sa = res
Try
s = Socket.socket (AF, Socktype, Proto)
Except Socket.error as msg:
s = None
Continue
Try
S.bind (SA)
S.listen (1)
Except Socket.error as msg:
S.close ()
s = None
Continue
Break
If S is None:
print ' could not open socket '
Sys.exit (1)
conn, addr = S.accept ()
print ' Connected by ', addr
While 1:
data = CONN.RECV (1024)
If not data:break
Conn.send (data)
Conn.close ()

Client

# Echo Client program
Import socket
Import Sys

host = ' localhost ' # The remote host
Port = 50007 # The same port as used by the server
s = None
For res in Socket.getaddrinfo (HOST, PORT, Socket.af_unspec, socket. SOCK_STREAM):
AF, Socktype, Proto, canonname, sa = res
Try
s = Socket.socket (AF, Socktype, Proto)
Except Socket.error as msg:
s = None
Continue
Try
S.connect (SA)
Except Socket.error as msg:
S.close ()
s = None
Continue
Break
If S is None:
print ' could not open socket '
Sys.exit (1)
S.sendall (' Hello, World ')
data = S.RECV (1024)
S.close ()
print ' Received ', repr (data)

Above we mentioned the basic form of socket programming, this section we enhance the performance of the service side!

#!/usr/bin/env python

Import socket, threading

Class Clientthread (threading. Thread):

def __init__ (self, IP, port, socket):
Threading. Thread.__init__ (self)
Self.ip = IP
Self.port = Port
Self.socket = socket
print [+] New thread started for "+ip+": "+str (port)

def run (self):
Print "Connection from:" +ip+ ":" +str (port)

Self.socket.send ("\nwelcome to the server\n\n")

data = "Dummydata"

While Len (data):
data = SELF.SOCKET.RECV (2048)
Print "Client Sent:" +data
Self.socket.send ("You sent me:" +data)

Print "Client disconnected ..."

Host = "0.0.0.0"
Port = 9999

Tcpsock = Socket.socket (socket.af_inet, socket. SOCK_STREAM)
Tcpsock.setsockopt (socket. Sol_socket, SOCKET. SO_REUSEADDR, 1)

Tcpsock.bind ((Host,port))
Threads = []

While True:
Tcpsock.listen (4)
Print "\nlistening for incoming connections ..."
(Clientsock, (IP, port) = Tcpsock.accept ()
Newthread = Clientthread (IP, port, Clientsock)
Newthread.start ()
Threads.append (Newthread)

For T in Threads:
T.join ()