file_get_contents does not send data content in a POST request - php

Question

I am attempting to send a POST request to an arduino from a PHP script that is called by a web page. I am using file_get_contents() to accomplish this. I have read the examples from the PHP manual here: Here. It appears that the Arduino is receiving the POST request but there is no content included in the data stream, only headers and content parameters. Here is my relevant php
// send database updates to the arduino
$url = 'http://'.$ip;
$options = array(
'http' => array(
'header' => "Content-type: application/x-www/form-urlencoded\r\n",
'method' => 'POST',
'content' => http_build_query($responseText)
),
);
$context = stream_context_create($options);
$result = file_get_contents($url, false, $context);
currently on the Arduino I am just dumping the entire POST request to the terminal so that I can verify that it is being received. Here is the output of the Arduino terminal.
Ethernet WebServer Example
server is at 192.168.3.3
new client
POST / HTTP/1.0
Host: 192.168.3.3
Connection: close
Content-Length: 80
Content-type: application/x-www/form-urlencoded
client disconnected
As you can see the entire POST request is there accept the content. It shows the Content-Length but no actual content.
Here is the Arduino code that produced the terminal output. It is nothing more than the Web Server example that comes with the Arduino IDE.
/*
Web Server
A simple web server that shows the value of the analog input pins.
using an Arduino Wiznet Ethernet shield.
Circuit:
* Ethernet shield attached to pins 10, 11, 12, 13
* Analog inputs attached to pins A0 through A5 (optional)
created 18 Dec 2009
by David A. Mellis
modified 9 Apr 2012
by Tom Igoe
modified 02 Sept 2015
by Arturo Guadalupi
*/
#include <SPI.h>
#include <Ethernet.h>
// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(192, 168, 3, 3);
// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);
String postData;
void setup() {
// You can use Ethernet.init(pin) to configure the CS pin
Ethernet.init(10); // Most Arduino shields
//Ethernet.init(5); // MKR ETH shield
//Ethernet.init(0); // Teensy 2.0
//Ethernet.init(20); // Teensy++ 2.0
//Ethernet.init(15); // ESP8266 with Adafruit Featherwing Ethernet
//Ethernet.init(33); // ESP32 with Adafruit Featherwing Ethernet
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
Serial.println("Ethernet WebServer Example");
// start the Ethernet connection and the server:
Ethernet.begin(mac, ip);
// Check for Ethernet hardware present
if (Ethernet.hardwareStatus() == EthernetNoHardware) {
Serial.println("Ethernet shield was not found. Sorry, can't run without hardware. :(");
while (true) {
delay(1); // do nothing, no point running without Ethernet hardware
}
}
if (Ethernet.linkStatus() == LinkOFF) {
Serial.println("Ethernet cable is not connected.");
}
// start the server
server.begin();
Serial.print("server is at ");
Serial.println(Ethernet.localIP());
}
void loop() {
// listen for incoming clients
EthernetClient client = server.available();
if (client) {
Serial.println("new client");
// an http request ends with a blank line
boolean currentLineIsBlank = true;
while (client.connected()) {
if (client.available()) {
char c = client.read();
//postData = postData + c;
Serial.write(c);
// if you've gotten to the end of the line (received a newline
// character) and the line is blank, the http request has ended,
// so you can send a reply
if (c == '\n' && currentLineIsBlank) {
// send a standard http response header
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connection: close"); // the connection will be closed after completion of the response
//client.println("Refresh: 5"); // refresh the page automatically every 5 sec
client.println();
/*client.println("<!DOCTYPE HTML>");
client.println("<html>");
// output the value of each analog input pin
for (int analogChannel = 0; analogChannel < 6; analogChannel++) {
int sensorReading = analogRead(analogChannel);
client.print("analog input ");
client.print(analogChannel);
client.print(" is ");
client.print(sensorReading);
client.println("<br />");
}
client.println("</html>");*/
break;
}
if (c == '\n') {
// you're starting a new line
currentLineIsBlank = true;
} else if (c != '\r') {
// you've gotten a character on the current line
currentLineIsBlank = false;
}
}
}
// give the web browser time to receive the data
delay(1);
Serial.println("client disconnected");
}
}
What is causing the content of the POST request to not be sent from the PHP?

Answer 1

After I let my brain rest for about half a day I determined the cause of my problem. It was not in the PHP at all. It was being caused by this IF block in the Arduino code
if (c == '\n' && currentLineIsBlank) {
// send a standard http response header
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connection: close");
//client.println("Refresh: 5");
client.println();
/*client.println("<!DOCTYPE HTML>");
client.println("<html>");
// output the value of each analog input pin
for (int analogChannel = 0; analogChannel < 6; analogChannel++) {
int sensorReading = analogRead(analogChannel);
client.print("analog input ");
client.print(analogChannel);
client.print(" is ");
client.print(sensorReading);
client.println("<br />");
}
client.println("</html>");*/
break;
}
it was causing while loop that it is nested in to terminate at the blank line between the header and the content. My new working code for the Arduino is
#include <SPI.h>
#include <Ethernet.h>
// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(192, 168, 3, 3);
// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);
String postData;
void setup() {
// You can use Ethernet.init(pin) to configure the CS pin
Ethernet.init(10); // Most Arduino shields
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for native USB port only
}
Serial.println("Ethernet WebServer Example");
// start the Ethernet connection and the server:
Ethernet.begin(mac, ip);
// Check for Ethernet hardware present
if (Ethernet.hardwareStatus() == EthernetNoHardware) {
Serial.println("Ethernet shield was not found. Sorry, can't run without hardware. :(");
while (true) {
delay(1); // do nothing, no point running without Ethernet hardware
}
}
if (Ethernet.linkStatus() == LinkOFF) {
Serial.println("Ethernet cable is not connected.");
}
// start the server
server.begin();
Serial.print("server is at ");
Serial.println(Ethernet.localIP());
}
void loop() {
// listen for incoming clients
EthernetClient client = server.available();
if (client) {
Serial.println("new client");
while (client.connected()) {
while (client.available()) {
char c = client.read();
postData = postData + c;
// send a standard http response header
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connection: close");
client.println();
}
client.stop();
}
// give the web browser time to receive the data
delay(1);
Serial.println("\r\nclient disconnected");
Serial.println(postData);
Serial.println(postData.substring(postData.indexOf("status=")+7, postData.indexOf("status=")+8 ));
}
}