Ciao a tutti, sto cercando di realizzare un semplice proxy HTTP in java, ma non riesco a venirne fuori. Il programma effettua questi passaggi:
1. intercetta le richieste HTTP inviate da un browser (con ServerSocket in ascolto)
2. esamina la HTTP request e "preleva" l'url della destinazione
3. crea una nuova HTTP request e si collega all'url destinazione
4. riceve la HTTP response dalla destinazione
5. inoltra la HTTP response al browser
In teoria funziona, ma nella pratica ho problemi a visualizzare alcuni siti, credo per via della codifica (encoding gz? utf-8?). La trasmissione della risposta da server a proxy e poi a client viene realizzata semplicemente leggendo/scrivendo byte, per evitare di andare a usare filtri con la possibilità di modificare/danneggiare i dati. Dunque non dovrebbe modificarsi niente se leggo/scrivo byte semplicemente?! Invece ho l'impressione che il browser abbia problemi a leggere la risposta e/o a decodificare i dati. Ho provato anche a decodificare i dati con GZIP*Stream, ma non riesco comunque a vedere tutte le pagine. Spero di aver esposto bene il problema!
Chiedo consiglio agli esperti...
Grazie!
Ecco il codice bozza:
codice:import java.net.*; import java.io.*; import java.util.*; import java.util.zip.*; //architecture: client <-> proxy <-> Internet public class HTTPProxy { /*** FIELDS ***/ private ServerSocket proxySocket= null; private Socket clientSocket= null; private BufferedReader CinputP= null; //input stream of proxy, client -> server private BufferedOutputStream PoutputC= null; //output stream of proxy, server -> client private BufferedInputStream IinputP= null; //input stream of proxy, Internet -> proxy private HttpURLConnection connection= null; private URL url= null; //URL requested from client private int server_port; private final int default_server_port= 9090; /*** CONSTRUCTORS ***/ public HTTPProxy() { server_port= default_server_port; } public HTTPProxy(int port) { server_port= port; } /*** METHODS ***/ public void start() { try { proxySocket= new ServerSocket(server_port); //open 9090 port System.out.println("Started server... on " + proxySocket.getLocalPort()); }catch(IOException ioe) { System.out.println("Attention: could not listen on port " + server_port + "!"); System.exit(-1); } while(true) { try { clientSocket= proxySocket.accept(); //accept incoming connections CinputP= new BufferedReader(new InputStreamReader(clientSocket.getInputStream()), 1000); String inputFromClient; ArrayList<String> arrayHttpRequest= new ArrayList<String>(0); //connectionToURL: while(((inputFromClient= CinputP.readLine()) != null) && (!inputFromClient.trim().isEmpty())) { arrayHttpRequest.add(inputFromClient); } //start request of URL, proxy -> Internet connect(arrayHttpRequest); if(connection != null) { PoutputC= new BufferedOutputStream(clientSocket.getOutputStream(), 1000); int inputFromInternet; System.out.println("Forwarding response to client..."); System.out.println("encoding..." + connection.getContentEncoding()); IinputP= new BufferedInputStream(connection.getInputStream(), 1000); while((inputFromInternet=IinputP.read()) != -1) { PoutputC.write(inputFromInternet); //proxy -> client } PoutputC.flush(); }else { System.exit(-1); } }catch(IOException ioe) { System.out.println("Attention: accept failed on port " + server_port + "!"); System.exit(-1); }finally { try { PoutputC.close(); CinputP.close(); IinputP.close(); }catch(IOException ex) { ex.printStackTrace(); } } } } private void connect(ArrayList<String> request) throws IOException, ProtocolException, MalformedURLException { String requestLine= request.get(0); url= new URL(extractURL(requestLine)); //fetch request line System.out.println("Connection... " + url.toString()); connection= (HttpURLConnection)url.openConnection(); connection.setRequestMethod(extractMethod(requestLine)); //check and set HTTP method int endHeader; String header, requestField; for(int i= 1; i < request.size(); i++) {//scan HTTP fields and create a new HTTP request requestField= request.get(i); endHeader= requestField.indexOf(":"); header= requestField.substring(0, endHeader); connection.addRequestProperty(header, requestField.substring(endHeader+2)); } connection.setDoOutput(true); connection.connect(); System.out.println("Established connection."); } //extract URL from the request line (the first) of an HTTP request private String extractURL(String requestLine) { int start= requestLine.indexOf(" ") + 1; //first empty space int end= requestLine.lastIndexOf(" "); //last empty space return requestLine.substring(start, end); } //check and return HTTP method of a HTTP request private String extractMethod(String requestLine) throws IOException { int endMethod= requestLine.indexOf(" "); String method= requestLine.substring(0, endMethod); if(method.equals("GET")) { return "GET"; }else if(method.equals("HEAD")) { return "HEAD"; }else if(method.equals("POST")) { return "POST"; }else if(method.equals("PUT")) { return "PUT"; }else if(method.equals("DELETE")) { return "DELETE"; }else if(method.equals("TRACE")) { return "TRACE"; }else if(method.equals("CONNECT")) { return "CONNECT"; }else if(method.equals("OPTIONS")) { return "OPTIONS"; }else {//wrong request throw new IOException(); } } }
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! Boh!
