Arduino - No Delay loop with wifi client failing - arduino

Question

Anyone who feels the title is incorrect or misleading, please feel free to update it.
The issue I'm having is with my Uno R3 and WiFi Shield. I really can't share the exact source right now, but this will explain the issue pretty well:
#include <WiFi.h>
#include <SPI.h>
#include <Ethernet.h>
char httpHost[] = "my.local.site.com";
IPAddress server(192,168,1,10);
int serverPort = 80;
char ssid[] = "myssid";
char password[] = "abcd123456";
int thingy = 0;
float lastTick = 0;
float tickInterval = 30000;
WiFiClient client;
boolean lastConnected = false;
void setup()
{
Serial.begin(9600);
connectWifi();
pinMode(2, INPUT);
}
void loop()
{
float currentMillis = millis();
if (currentMillis >= (lastTick + tickInterval) || currentMillis < lastTick) {
pollThingy();
logUpdate();
lastTick = currentMillis;
}
while (client.available()) {
char c = client.read();
Serial.print(c);
}
if (client.connected() == false && lastConnected == true) {
Serial.println("-- Disconnected.");
client.stop();
}
lastConnected = client.connected();
if (lastConnected == true) {
digitalWrite(13, HIGH);
} else {
digitalWrite(13, LOW);
}
}
void connectWifi()
{
int status = WL_IDLE_STATUS;
if (WiFi.status() == WL_NO_SHIELD) {
Serial.println("No WiFi Shield Found! Aborting!");
while(true) { }
}
int i = 0;
while(true) {
Serial.print("Attempting to connect to network: ");
Serial.print(ssid);
Serial.print(" Attempt #");
Serial.println(++i);
status = WiFi.begin(ssid, password);
if (status == WL_CONNECTED) break;
delay(10000);
}
if (status == WL_CONNECTED) {
Serial.println("Connected!");
} else {
Serial.println("Failed connecting! Aborting!");
while(true) { }
}
}
void pollThingy()
{
thingy = digitalRead(2);
}
void logUpdate()
{
Serial.println("Logging update: ");
if (client.connected() == false) {
Serial.print("-- Connecting to ");
Serial.print(server);
Serial.print(":");
Serial.println(serverPort);
if (client.connect(server, serverPort)) {
Serial.println(" Connected!");
client.print("GET /some/Uri/with/arguments?output=json HTTP/1.1");
client.println(" HTTP/1.1");
client.print("Host: ");
client.println(httpHost);
client.println("Connection: close");
client.println();
} else {
Serial.println(" Connection failed!");
}
} else {
Serial.println("-- Already connected... Skipping, this time...");
}
}
Now the issue I'm having seems to be kinda crazy. This will work fine and log an update to the given endpoint every 30 seconds as expected. However, after about 2 hours it just stalls and fails to do anything again. I've confirmed by watching the serial monitor, which returns nothing other than the last expected Serial.println() statements, but there are no errors to be displayed or anything.
I haven't updated the firmware on the WiFi shield since I got it, and I honestly couldn't tell you what revision it's running. However, I feel like this is something else entirely and I just can't put my finger on it.
Can anyone offer any advice?
Please don't beat me up too much about my code style. This is just a first draft.

Answer 1

You never close the connections you open. You show a connection to a web server, but no Keep-Alive header. The server should not be letting people sit on open connections just in case there is additional transactions to follow. I would expect the server to drop the connections.
The Arduino code never closes a connection, it just keeps opening another every time it sees the server has disconnected. At some point, the network stack runs out of handles to keep track of the debris.
For 30 s intervals, there is no reason to try to keep a connection open to a web server. Add a
client.stop()
after the last println().
You could confirm what is going on with two tools:
- netstat (or similar) would tell you if the server is accumulating connections in CLOSE_WAIT or TIME_WAIT
- Wireshark would let you see if the server is trying to close the connection and not being acknowledged by the Arduino.