COMPUTER NETWORKS LAB
LIST OF PROGRAMS
S.no 1
Name of the Program Socket programming
Page no
2
Data grams
3
TCP
4
SMTP
5
FTP
6
Implementation of any two congestion control algorithms
2
SOCKET PROGRAMMING
Ex. No 1 Program for Echo Client and Echo Server Aim To write a program in c/ java to implement echo client and echo server. Algorithm 1. Start 2. Create necessary input and output streams 3. Create a socket connection from client to the server with corresponding IP address and port number 4. Get any string from the client side console 5. Pass this string to the server which echoes back to the client 6. Read the same string from the client side socket’s input stream. 7. Display the output string that is echoed back to the client. Program Client //echoclient.java import java.io.*; import java.net.*; public class echoclient { public static void main(String args[]) { try { Socket s=new Socket("localhost",9999); BufferedReader r = new BufferedReader(new InputStreamReader(s.getInputStream())); PrintWriter w=new PrintWriter(s.getOutputStream(),true); BufferedReader con = new BufferedReader (new InputStreamReader(System.in)); String line,rline; do { line=con.readLine(); if(line!=null) { w.println(line); }
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rline=r.readLine(); System.out.println("Echo from server"+rline); }while(!line.trim().equals("bye")); } catch(Exception err) { System.out.println("error"+err); } } } Server // echoServer.java import java.io.*; import java.net.*; public class echoServer { public static void main (String args[]) { try { ServerSocket ser = new ServerSocket(9999); while(true) { Socket client = ser.accept(); BufferedReader r=new BufferedReader(new InputStreamReader(client.getInputStream())); PrintWriter w=new PrintWriter(client.getOutputStream(),true); System.out.println("Welcome to java echoserver"); String line; do { line =r.readLine (); if(line!=null) w.println("SERVER:"+line); System.out.println (line); } while (! line.trim().equals("bye")); if(line.equals("bye")) System.exit(0); client.close(); } } catch(Exception err) { System.out.println("Error:"+err);
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} } } Output
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RESULT Thus a program is written to implement the echo client and echo server Ex. No 2
Program to Implement DNS using UDP
Aim To Write a program to implement the Domain Name System using UDP Algorithm 1. Start 2. Declare the necessary variables for the predefined structures hostent and utsname 3. Get the hostname from the user through console 4. get the ip address of the hostname using the function gethostbyname() 5. Display the ip address corresponding to the hostname. 6. Stop Program // Print out DNS Record for an Internet Address import javax.naming.directory.Attributes; import javax.naming.directory.InitialDirContext; import javax.naming.NamingEnumeration; import javax.naming.NamingException; import java.net.InetAddress; import java.net.UnknownHostException; public class DNSLookup { public static void main(String args[]) { // explain what program does and how to use it if (args.length != 1) { System.err.println("Print out DNS Record for an Internet Address"); System.err.println("USAGE: java DNSLookup domainName| domainAddress"); System.exit(-1); } try { InetAddress inetAddress; // if first character is a digit then assume is an address if (Character.isDigit(args[0].charAt(0))) { // convert address from string representation to byte array byte[] b = new byte[4]; String[] bytes = args[0].split("[.]");
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for (int i = 0; i < bytes.length; i++) { b[i] = new Integer(bytes[i]).byteValue(); } // get Internet Address of this host address inetAddress = InetAddress.getByAddress(b); } else { // get Internet Address of this host name inetAddress = InetAddress.getByName(args[0]); } // show the Internet Address as name/address System.out.println(inetAddress.getHostName() + "/" + inetAddress.getHostAddress()); // get the default initial Directory Context InitialDirContext iDirC = new InitialDirContext(); // get the DNS records for inetAddress Attributes attributes = iDirC.getAttributes("dns:/" + inetAddress.getHostName()); // get an enumeration of the attributes and print them out NamingEnumeration attributeEnumeration = attributes.getAll(); System.out.println("-- DNS INFORMATION --"); while (attributeEnumeration.hasMore()) { System.out.println("" + attributeEnumeration.next()); } attributeEnumeration.close(); } catch (UnknownHostException exception) { System.err.println("ERROR: No Internet Address for '" + args[0] + "'"); } catch (NamingException exception) { System.err.println("ERROR: No DNS record for '" + args[0] + "'"); } } }
Output
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Result Thus a program is written to implement the Domain Name System. Ex. No 3 TCP programs a. Program to Implement Chatting Application Aim To Write a C++ program to prepare Students Report using Simple Class with primitive and array data types Algorithm 1. Start 2. Create necessary input and output streams 3. Create a socket connection from user1 to the user2 with corresponding IP address and port number 4. Get any string from the user1 side console 5. Pass this string to the user2 which prints in the console of user2 6. Read some other string from the user2 side socket’s input stream. 7. Pass this string to the user1 which prints in the console of user1 8. Repeat the same until “exit” command 9. Stop Program User1 import java.io.*; import java.net.*; class user1 { public static void main(String arg[]) throws Exception { String sentence, newsentence; DataInputStream in=new DataInputStream(System.in); Socket cs=new Socket("10.1.1.204",6789); DataInputStream inp=new DataInputStream(cs.getInputStream()); DataOutputStream out=new DataOutputStream(cs.getOutputStream()); do { System.out.print("User1:"); sentence=in.readLine(); if(sentence.compareTo("exit")!=0) { out.writeBytes(sentence+'\n'); newsentence=inp.readLine(); System.out.println("User2:"+newsentence); }
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}while(sentence.compareTo("exit")!=0); cs.close(); } } User 2 import java.io.*; import java.net.*; class user2 { public static void main(String arg[]) throws Exception { String sentence, newsentence; DataInputStream in=new DataInputStream(System.in); ServerSocket ss=new ServerSocket(6789); Socket s=ss.accept(); DataInputStream inp=new DataInputStream(s.getInputStream()); DataOutputStream out=new DataOutputStream(s.getOutputStream()); do { sentence=inp.readLine(); if(sentence.compareTo("exit")!=0) { System.out.println("User1:"+sentence); System.out.print("User2:"); newsentence=in.readLine(); out.writeBytes(newsentence+'\n'); } }while(sentence.compareTo("exit")!=0); } } Output
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RESULT Thus a program is written to implement the chatting application using TCP sockets. b. Program to Implement Concurrent Server Aim To Write a program to implement the concept of concurrent server. Algorithm 1. Start 2. Create the necessary sockets in the client and server side systems 3. Initialize a thread in the server side system using runnable interface 4. Accept the connection requisition from the client side systems inside the thread. 5. Initialize necessary input and output streams for the accepted connection inside the thread. 6. Run any number of clients in parallel communicating the same server. 7. The server will respond all the clients at the same time 8. Stop Program Client 1/ Client 2 / any clients import java.io.*; import java.net.*; class Clientcon { public static void main(String arg[]) throws Exception { String sentence, newsentence,newsentence1; DataInputStream in=new DataInputStream(System.in); Socket cs=new Socket("pgcse220",6789); DataInputStream inp=new DataInputStream(cs.getInputStream()); DataOutputStream out=new DataOutputStream(cs.getOutputStream()); sentence=inp.readLine(); System.out.println(sentence); newsentence=in.readLine(); out.writeBytes(newsentence+'\n'); newsentence1=inp.readLine(); System.out.println("From Server:"+newsentence1); cs.close(); } } Server import java.io.*;
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import java.net.*;
class Server { public static void main(String arg[]) throws Exception { int count=0; Thread t= Thread.currentThread(); ServerSocket ss=new ServerSocket(6789); while(true) { try { Socket s=ss.accept(); count++; conserver c =new conserver(s, count); } catch(Exception e) {} } } } class conserver implements Runnable { Thread t; Socket s; int c; conserver(Socket s1,int count) { t=new Thread(this, "Demo"); t.start(); s=s1; c=count; } public void run() { try { DataInputStream inp=new DataInputStream(s.getInputStream()); DataOutputStream out=new DataOutputStream(s.getOutputStream()); String sentence="Enter the String:"; String newsentence; out.writeBytes(sentence+'\n'); newsentence=inp.readLine();
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//Thread.sleep(10000); System.out.println("From Client"+c+":"+newsentence); out.writeBytes(newsentence+'\n'); } catch(Exception e) {} } } Output
Result Thus a program is written to implement the concurrent server
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Ex. No 4 Program for simple mail transfer protocol
Aim To Write a program to implement the concept of SMTP server.
Algorithm
PROGRAM
//SMTP Server import java.io.*; import java.net.*; class smtpServer { public static void main (String args[]) throws Exception { ServerSocket ss = new ServerSocket(8080); Socket s = ss.accept(); ServiceClient(s); } public static void ServiceClient (Socket s) throws Exception { DataInputStream dis = null ; PrintStream ps = null ;
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dis = new DataInputStream (s.getInputStream()) ; ps = new PrintStream (s.getOutputStream()); FileWriter f = new FileWriter ("TestMail.eml") ; String tel=dis.readLine(); if(tel.equals("Ready")) System.out.println ("Ready signal Received from client") ; ps.println("Enter the From address:"); String from = dis.readLine() ; f.write("From:" +from+ "\n") ; ps.println("Enter the To address:"); String to = dis.readLine(); f.write("To:" + to + "\n"); ps.println("Enter the Subject:"); String sub = dis.readLine(); f.write("Subject:" + sub + "\n"); ps.println("Enter the Message:"); String msg = dis.readLine(); f.write("\nMessage: " + msg + "\n" ) ; f.close(); } }
// SMTP Client import java.io.*; import java.net.*; class smtpClient { public static void main (String args[]) throws Exception { Socket s=new Socket("localhost",8080); DataInputStream dis = new DataInputStream(s.getInputStream()); DataInputStream in = new DataInputStream(System.in); PrintStream ps = new PrintStream(s.getOutputStream()); ps.println("Ready"); System.out.println (dis.readLine()); String strFrom=in.readLine(); ps.println(strFrom);
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System.out.println (dis.readLine()); String strTo=in.readLine(); ps.println(strTo); System.out.println (dis.readLine()); String strSub=in.readLine(); ps.println(strSub); System.out.println (dis.readLine()); while(true) { String msg=in.readLine(); ps.println(msg); if(msg.equals("Quit")) { System.out.println ("Message is delivered to server and client quits"); break; } } } } OUTPUT Z:\Programs\SMTP>javac smtpServer.java Z:\Programs\SMTP>javac smtpClient.java
Z:\Programs\SMTP>java smtpServer
Ready signal Received from client Z:\Programs\SMTP>
Z:\Programs\SMTP>java smtpClient
Enter the From address:
[email protected] Enter the To address:
[email protected] Enter the Subject:
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Test Mail Enter the Message: Hello, this mail is generated as part of the SMTP program testing! Quit Message is delivered to server and client quits Z:\Programs\SMTP>
// Generated Mail
Result
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Thus a program is written to implement the SMTP client and SMTP server Ex. No 5
Program to Implement File Transfer
Aim To write a program in c/ java to implement file transfer between client and file server. Algorithm 1. Start 2. Create necessary input and output streams 3. Create a socket connection from client to the server with corresponding IP address and port number 4. Create necessary file streams 5. Get the option from the user to UPLOAD/ DOWNLOAD and the file name to be transferred 6. If UPLOAD, read each byte from the file in the client side and write it into the output stream of the socket 7. In the server side, read the bytes from the input stream and write it into the file Program Client import java.io.*; import java.net.*; class user { public static void main(String arg[]) throws Exception { long end; String fname,f1name; int size=0; String option; DataInputStream in=new DataInputStream(System.in); Socket cs=new Socket("10.1.1.204",6789); DataInputStream inp=new DataInputStream(cs.getInputStream()); DataOutputStream out=new DataOutputStream(cs.getOutputStream()); System.out.println("A. UPLOAD"); System.out.println("B. DOWNLOAD"); System.out.print("ENTER THE OPTION:"); option=in.readLine(); out.writeBytes(option+"\n"); if(option.compareTo("A")==0) { System.out.println("Enter the file name:");
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fname=in.readLine(); System.out.println("Enter the file name to be saved in Server:"); f1name=in.readLine(); out.writeBytes(f1name+'\n'); File f=new File(fname); FileInputStream fi=new FileInputStream(fname); size=fi.available(); byte b[]=new byte[size]; fi.read(b); fi.close(); out.write(b); System.out.println("UPLOADED!!!!!"); } else if(option.compareTo("B")==0) { System.out.println("Enter the file name :"); fname=in.readLine(); System.out.println("Enter the file name to be saved :"); f1name=in.readLine(); out.writeBytes(fname+'\n'); byte b[]=new byte[400]; inp.read(b); File f=new File(f1name); FileOutputStream fo=new FileOutputStream(f1name); fo.write(b); fo.close(); System.out.println("DOWNLOADED!!!!!"); } else { System.out.println("Enter Valid Option"); } cs.close(); end = System.currentTimeMillis(); } } File Server import java.io.*; import java.net.*; class FileServer { public static void main(String arg[]) throws Exception { String fname, f1name, option; DataInputStream in=new DataInputStream(System.in);
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ServerSocket ss=new ServerSocket(6789); while(true) { Socket s=ss.accept(); DataInputStream inp=new DataInputStream(s.getInputStream()); DataOutputStream out=new DataOutputStream(s.getOutputStream()); option=inp.readLine(); if(option.compareTo("A")==0) { f1name=inp.readLine(); try { File f=new File(f1name); FileOutputStream fo=new FileOutputStream(f); byte b[]=new byte[400]; inp.read(b); fo.write(b); fo.close(); System.out.println("File "+f1name+" UPLOADED!!!!!"); } catch(FileNotFoundException e) { String excep = "Sorry... File Not Present"; System.out.println(excep); break; } } else if(option.compareTo("B")==0) { fname=inp.readLine(); try { File f=new File(fname); InputStream fi=new FileInputStream(f); System.out.println("Accessed file :" + fname); int size=fi.available(); byte b[]=new byte[size]; fi.read(b); fi.close(); out.write(b); System.out.println("Successfully send"); } catch(FileNotFoundException e) { String excep = "Sorry... File Not Present"; System.out.println(excep);
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break; } } else { System.out.println("Enter Valid Option"); } }
}
}
Output
RESULT Thus a program is written to perform functions with default arguments
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