[HTTPCLIENT-116] Request/Response race condition when doing multiple requests on the same connection.

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 2.0 Beta 1
• Component/s: HttpClient (classic)
• Environment: Operating System: All; Platform: PC
• Bugzilla Id: 13463
• Assignee: Michael Becke
• Reporter: mike.vannoord
• Created: 09/Oct/02 23:58
• Updated: 22/Apr/07 07:10
• Resolved: 15/May/06 21:44

Description

If one tries to do multiple request over the same socket connection a race
condition occurs in the input/output streams.
eg.
– Some request -->
<- HTTP/1.1 200 OK
<- Some: Headers
<-
<- The body.

– Next request -->
<- HTTP/1.1 200 OK
<- More: Headers
<-
<- Some data.

If the second request is sent, but the second response isn't yet received
before the client starts to try to read it, it'll get
a "org.apache.commons.httpclient.HttpRecoverableException: Error in parsing the
status line from the response: unable to find line starting with "HTTP/""
exception (it will think "The body." is part of the second response).

The following code will reproduce the problem:

import java.io.*;
import java.net.*;
import java.util.*;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.*;

public class HttpClientRaceBug {
public static void main(String[] args) {
try {
SimpleHttpServer.listen(8987);
HttpClient client = new HttpClient();
client.startSession("localhost", 8987);
client.getState().setCredentials("Test Realm",
new UsernamePasswordCredentials("foo", "bar"));

for (int i = 0; i < 100; i++)

{ GetMethod meth = new GetMethod(); client.executeMethod(meth); }

} catch (Exception e)

{ e.printStackTrace(); }

}

private static final class SimpleHttpServer implements Runnable {
private Socket socket;
public SimpleHttpServer(Socket socket)

{ this.socket = socket; }

public static void listen(final int port) {
Thread server = new Thread() {
public void run() {
try {
ServerSocket ss = new ServerSocket(port);
while (true)

{ new Thread(new SimpleHttpServer(ss.accept())).start(); }

} catch (Exception e)

{ e.printStackTrace(); }

}
};

server.setDaemon(true);
server.start();
}
public void run() {
try {
BufferedReader in = new BufferedReader(new
InputStreamReader(this.socket.getInputStream()));

int len = 0;
boolean auth = false;
String line;
while ((line = in.readLine()) != null) {
System.out.println("> " + line);

if (line.trim().equals(""))

{ in.read(new char[len]); doOutput(auth); auth = false; len = 0; }

else if (line.indexOf(':') > -1) {
StringTokenizer tok = new StringTokenizer(line, ":");
String key = tok.nextToken().toLowerCase();
if (key.equals("content-length"))

{ len = Integer.parseInt(tok.nextToken().trim()); }

else if (key.equals("authorization"))

{ auth = true; }

}
}
} catch (Exception e) {}
}
private static int count = 0;
public void doOutput(boolean authorized) throws IOException {
Writer out = new OutputStreamWriter(this.socket.getOutputStream());
count++;

String id = (count < 100) ?
((count < 10) ? "00" + count : "0" + count) : "" + count;
if (authorized)

{ write(out, "HTTP/1.1 200 OK\r\n"); }

else

{ write(out, "HTTP/1.1 401 Unauthorized\r\n"); }

write(out, "WWW-Authenticate: Basic realm=\"Test Realm\"\r\n");
write(out, "Response-Id: " + id + "\r\n");
write(out, "Content-Type: text/html; charset=iso-8859-1\r\n");
write(out, "Content-Length: 17\r\n\r\n");
write(out, "My Response (" + id + ")");
out.close();
}
private void write(Writer out, String text) throws IOException

{ System.out.print("< " + text); out.write(text); }

}
}