Transcript Sockets Part 6
CS 471/571 Sockets Part 6
Quiz 6
• • Same material as quiz 5 and the following Write small program segments using Java to – Create a TCP server socket – Create a datagram socket – Create a connection to a TCP server socket – Accept a TCP connection request – Send/Receive a datagram packet – Send/Receive bytes to a TCP socket
Web Server
• • • Implement a very simple Web Server that can process GET requests Java C
HTTP request message: general format
method sp URL header field name sp value version cr lf cr lf request line header lines header field name cr lf value cr lf entity body body Application Layer 2-4
HTTP response message: general format
version sp Status code header field name sp value sp phrase cr cr lf lf status line header lines header field name cr lf sp value cr lf entity body body Application Layer 2-5
Simple Web Server in Java (from previous version of Kurose and Ross)
import java.io.*; import java.net.* ; import java.util.* ; public final class WebServer { public static void main(String argv[]) throws Exception { // Get the port number from the command line.
int port = (new Integer(argv[0])).intValue(); // Establish the listen socket.
ServerSocket socket = new ServerSocket(port); // Process HTTP service requests in an infinite loop.
Simple Web Server (Java)
while (true) { // Listen for a TCP connection request.
Socket connection = socket.accept(); // Construct an object to process the HTTP request message.
HttpRequest request = new HttpRequest(connection); // Create a new thread to process the request.
Thread thread = new Thread(request); } } } // Start the thread.
thread.start();
Simple Web Server (Java)
import java.io.* ; import java.net.* ; import java.util.* ; final class HttpRequest implements Runnable { final static String CRLF = "\r\n"; Socket socket; } public HttpRequest(Socket socket) throws Exception { this.socket = socket; } public void run() { try { processRequest(); } catch (Exception e) { System.out.println(e); }
Simple Web Server (Java)
private void processRequest() throws Exception { // Get a reference to the socket's input and output streams.
InputStream is = socket.getInputStream(); DataOutputStream os = new DataOutputStream(socket.getOutputStream()); // Set up input stream filters.
BufferedReader br = new BufferedReader(new InputStreamReader(is)); // Get the request line of the HTTP request message.
String requestLine = br.readLine(); // Extract the filename from the request line.
StringTokenizer tokens = new StringTokenizer(requestLine); tokens.nextToken(); // skip over the method, which should be "GET" String fileName = tokens.nextToken(); // Prepend a "." so that file request is within the current directory.
fileName = "." + fileName ;
Simple Web Server (Java)
// Open the requested file.
FileInputStream fis = null ; boolean fileExists = true ; try { fis = new FileInputStream(fileName); } catch (FileNotFoundException e) { fileExists = false ; } // Construct the response message.
String statusLine = null; String contentTypeLine = null; String entityBody = null;
Simple Web Server (Java)
if (fileExists) { statusLine = "HTTP/1.0 200 OK" + CRLF; contentTypeLine = "Content-Type: " + contentType(fileName) + CRLF; } else { statusLine = "HTTP/1.0 404 Not Found" + CRLF; contentTypeLine = "Content-Type: text/html" + CRLF; entityBody = "" + "
os.writeBytes(statusLine); // Send the content type line.
os.writeBytes(contentTypeLine); // Send a blank line to indicate the end of the header lines.
os.writeBytes(CRLF);
Simple Web Server (Java)
// Send the entity body.
if (fileExists) { sendBytes(fis, os); } fis.close(); } else { os.writeBytes(entityBody) ; } // Close streams and socket.
os.close(); br.close(); socket.close();
Simple Web Server (Java)
private static void sendBytes(FileInputStream fis, OutputStream os) throws Exception { // Construct a 1K buffer to hold bytes on their way to the socket.
byte[] buffer = new byte[1024]; int bytes = 0; } } // Copy requested file into the socket's output stream.
while ((bytes = fis.read(buffer)) != -1) { os.write(buffer, 0, bytes);
Simple Web Server (Java)
} private static String contentType(String fileName) { if(fileName.endsWith(".htm") || fileName.endsWith(".html")) { return "text/html"; } if(fileName.endsWith(".ram") || fileName.endsWith(".ra")) { return "audio/x-pn-realaudio"; } return "application/octet-stream" ; }
Simple Web Server ( C )
#include
Simple Web Server ( C )
} sockfd1 = socket(AF_INET, SOCK_STREAM, 0); memset(&server, 0, sizeof(struct sockaddr_in)); server.sin_family = AF_INET; server.sin_addr.s_addr = htonl(INADDR_ANY); server.sin_port = htons(12000); } bind(sockfd1, (struct sockaddr *) &server, sizeof(struct sockaddr_in)); listen(sockfd1, 5); while (1) { sockfd2 = accept(sockfd1, (struct sockaddr *) &client, &clen); s = (int *) malloc(sizeof(int)); *s = sockfd2; pthread_create(&t, NULL, processRequest, (void *) s);
Simple Web Server ( C )
void *processRequest(void *s) { //Only handles html case where file is found int sock = *((int *) s); char firstLine[1024]; char line[1024]; char delim[2] = " ”; char filename[100]; char *status1 = "HTTP/1.0 200 OK\r\n"; char *content1 = "Content-Type: text/html\r\n\r\n”; char *token; readFirstLine(firstLine, sock); token = strtok(firstLine, delim); token = strtok(NULL, delim);
Simple Web Server ( C )
} strcpy(filename, "."); strcat(filename, token); FILE *fp = fopen(filename, "r"); send(sock, status1, strlen(status1), 0); send(sock, content1, strlen(content1), 0); while (fgets(line, 1024, fp) != 0) { send(sock, line, strlen(line), 0); } close(sock); fclose(fp); return NULL;
Simple Web Server ( C )
} void readFirstLine(char firstLine[], int sock) { int i = 0; char c; int len; len = recv(sock, &c, 1, 0); while (len == 1 && c != '\n') { firstLine[i] = c;; i++; len = recv(sock, &c, 1, 0); } firstLine[i] = '\n'; firstLine[i+1] = '\0';