Problem with closed sockets in CC3000 library

00-README.md

Problem sequence:

• Server completes request and sends close.
• Client interrupt handler sets closed_sockets.
• Application closes socket before reading all input and so without calling connected when empty.
• Closed flag is still set on unused connection.
• New connection (CC3000 does not cycle socket numbers -- so almost always 0 again).
• Server is slow to respond so no input available.
• connected has closed and none available, so not connected.
• Connection failed.

Real world case of closing early is self-delimiting content, such as JSON.

slow_web.py

#!/usr/bin/env python

import time
import BaseHTTPServer

request_count = 0

class SlowHandler(BaseHTTPServer.BaseHTTPRequestHandler):
    def do_GET(self):
        global request_count
        request_count += 1
        print "Request #", request_count
        if request_count % 2 == 0:
            print "Sleeping..."
            time.sleep(5)
        self.send_response(200)
        self.send_header("Content-type", "text/plain")
        self.end_headers()
        self.wfile.write("Slow hello!")

if __name__ == '__main__':
    httpd = BaseHTTPServer.HTTPServer(("", 8080), SlowHandler)
    httpd.serve_forever()

WebClient.ino

/*************************************************** 
  This is an example for the Adafruit CC3000 Wifi Breakout & Shield

  Designed specifically to work with the Adafruit WiFi products:
  ----> https://www.adafruit.com/products/1469

  Adafruit invests time and resources providing this open source code, 
  please support Adafruit and open-source hardware by purchasing 
  products from Adafruit!

  Written by Limor Fried & Kevin Townsend for Adafruit Industries.  
  BSD license, all text above must be included in any redistribution
 ****************************************************/
 
 /*
This example does a test of the TCP client capability:
  * Initialization
  * Optional: SSID scan
  * AP connection
  * DHCP printout
  * DNS lookup
  * Optional: Ping
  * Connect to website and print out webpage contents
  * Disconnect
SmartConfig is still beta and kind of works but is not fully vetted!
It might not work on all networks!
*/
#include <Adafruit_CC3000.h>
#include <ccspi.h>
#include <SPI.h>
#include <string.h>
#include "utility/debug.h"

// These are the interrupt and control pins
#define ADAFRUIT_CC3000_IRQ   3  // MUST be an interrupt pin!
// These can be any two pins
#define ADAFRUIT_CC3000_VBAT  5
#define ADAFRUIT_CC3000_CS    10
// Use hardware SPI for the remaining pins
// On an UNO, SCK = 13, MISO = 12, and MOSI = 11
Adafruit_CC3000 cc3000 = Adafruit_CC3000(ADAFRUIT_CC3000_CS, ADAFRUIT_CC3000_IRQ, ADAFRUIT_CC3000_VBAT,
                                         SPI_CLOCK_DIVIDER); // you can change this clock speed

#define WLAN_SSID       "myNetwork"           // cannot be longer than 32 characters!
#define WLAN_PASS       "myPassword"
// Security can be WLAN_SEC_UNSEC, WLAN_SEC_WEP, WLAN_SEC_WPA or WLAN_SEC_WPA2
#define WLAN_SECURITY   WLAN_SEC_WPA2

#define IDLE_TIMEOUT_MS  3000      // Amount of time to wait (in milliseconds) with no data 
                                   // received before closing the connection.  If you know the server
                                   // you're accessing is quick to respond, you can reduce this value.

// What page to grab!
#define WEBSITE      "192.168.1.100"
#define WEBPAGE      "/"


/**************************************************************************/
/*!
    @brief  Sets up the HW and the CC3000 module (called automatically
            on startup)
*/
/**************************************************************************/

uint32_t ip;

void setup(void)
{
  Serial.begin(115200);
  Serial.println(F("Hello, CC3000!\n")); 

  Serial.print("Free RAM: "); Serial.println(getFreeRam(), DEC);
  
  /* Initialise the module */
  Serial.println(F("\nInitializing..."));
  if (!cc3000.begin())
  {
    Serial.println(F("Couldn't begin()! Check your wiring?"));
    while(1);
  }
  
  // Optional SSID scan
  // listSSIDResults();
  
  Serial.print(F("\nAttempting to connect to ")); Serial.println(WLAN_SSID);
  if (!cc3000.connectToAP(WLAN_SSID, WLAN_PASS, WLAN_SECURITY)) {
    Serial.println(F("Failed!"));
    while(1);
  }
   
  Serial.println(F("Connected!"));
  
  /* Wait for DHCP to complete */
  Serial.println(F("Request DHCP"));
  while (!cc3000.checkDHCP())
  {
    delay(100); // ToDo: Insert a DHCP timeout!
  }  

  /* Display the IP address DNS, Gateway, etc. */  
  while (! displayConnectionDetails()) {
    delay(1000);
  }

  ip = 0;
  // Try looking up the website's IP address
  Serial.print(WEBSITE); Serial.print(F(" -> "));
  while (ip == 0) {
    if (! cc3000.getHostByName(WEBSITE, &ip)) {
      Serial.println(F("Couldn't resolve!"));
    }
    delay(500);
  }

  cc3000.printIPdotsRev(ip);
  Serial.println();
  
  // Optional: Do a ping test on the website
  /*
  Serial.print(F("\n\rPinging ")); cc3000.printIPdotsRev(ip); Serial.print("...");  
  replies = cc3000.ping(ip, 5);
  Serial.print(replies); Serial.println(F(" replies"));
  */  

  for (int attempt = 1; attempt <= 4; attempt++) {
    Serial.print(F("Attempt #")); Serial.println(attempt);

  /* Try connecting to the website.
     Note: HTTP/1.1 protocol is used to keep the server from closing the connection before all data is read.
  */
  Adafruit_CC3000_Client www = cc3000.connectTCP(ip, 8080);
  if (www.connected()) {
    www.fastrprint(F("GET "));
    www.fastrprint(WEBPAGE);
    www.fastrprint(F(" HTTP/1.1\r\n"));
    www.fastrprint(F("Host: ")); www.fastrprint(WEBSITE); www.fastrprint(F("\r\n"));
    www.fastrprint(F("\r\n"));
    www.println();
  } else {
    Serial.println(F("Connection failed"));    
    return;
  }

  Serial.println(F("-------------------------------------"));
  
  /* Read data until either the connection is closed, or the idle timeout is reached. */ 
  unsigned long lastRead = millis();
  boolean done = false;
  while (!done && www.connected() && (millis() - lastRead < IDLE_TIMEOUT_MS)) {
    while (www.available()) {
      char c = www.read();
      Serial.print(c);
      lastRead = millis();
      if (c == '!') {
        done = true;
        break;
      }
    }
  }
  www.close();
  Serial.println(F("-------------------------------------"));
  
  }
  
  /* You need to make sure to clean up after yourself or the CC3000 can freak out */
  /* the next time your try to connect ... */
  Serial.println(F("\n\nDisconnecting"));
  cc3000.disconnect();
  
}

void loop(void)
{
 delay(1000);
}

/**************************************************************************/
/*!
    @brief  Begins an SSID scan and prints out all the visible networks
*/
/**************************************************************************/

void listSSIDResults(void)
{
  uint8_t valid, rssi, sec, index;
  char ssidname[33]; 

  index = cc3000.startSSIDscan();

  Serial.print(F("Networks found: ")); Serial.println(index);
  Serial.println(F("================================================"));

  while (index) {
    index--;

    valid = cc3000.getNextSSID(&rssi, &sec, ssidname);
    
    Serial.print(F("SSID Name    : ")); Serial.print(ssidname);
    Serial.println();
    Serial.print(F("RSSI         : "));
    Serial.println(rssi);
    Serial.print(F("Security Mode: "));
    Serial.println(sec);
    Serial.println();
  }
  Serial.println(F("================================================"));

  cc3000.stopSSIDscan();
}

/**************************************************************************/
/*!
    @brief  Tries to read the IP address and other connection details
*/
/**************************************************************************/
bool displayConnectionDetails(void)
{
  uint32_t ipAddress, netmask, gateway, dhcpserv, dnsserv;
  
  if(!cc3000.getIPAddress(&ipAddress, &netmask, &gateway, &dhcpserv, &dnsserv))
  {
    Serial.println(F("Unable to retrieve the IP Address!\r\n"));
    return false;
  }
  else
  {
    Serial.print(F("\nIP Addr: ")); cc3000.printIPdotsRev(ipAddress);
    Serial.print(F("\nNetmask: ")); cc3000.printIPdotsRev(netmask);
    Serial.print(F("\nGateway: ")); cc3000.printIPdotsRev(gateway);
    Serial.print(F("\nDHCPsrv: ")); cc3000.printIPdotsRev(dhcpserv);
    Serial.print(F("\nDNSserv: ")); cc3000.printIPdotsRev(dnsserv);
    Serial.println();
    return true;
  }
}