Connecting Arduino to Heroku web connected to Django database - api

Question

To describe my problem I was trying to connect my Arduino UNO to website created by me in Heroku.
Main purpose was to called rest api function in arduino conected to Internet and get a json data.
My Arduino code:
#include <ArduinoJson.h>
#include <Ethernet.h>
#include <SPI.h>
void setup() {
// Initialize Serial port
Serial.begin(9600);
while (!Serial) continue;
// Initialize Ethernet library
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
Ethernet.init(8); // use pin 53 for Ethernet CS
if (!Ethernet.begin(mac)) {
Serial.println(F("Failed to configure Ethernet"));
return;
}
delay(1000);
Serial.println(F("Connecting..."));
// Connect to HTTP server
EthernetClient client;
client.setTimeout(10000);
if (!client.connect("https://salty-cliffs-06856.herokuapp.com", 80)) {
Serial.println(F("Connection failed"));
return;
}
Serial.println(F("Connected!"));
// Send HTTP request
client.println(F("GET /api/command/ HTTP/1.1"));
client.println(F("Host: https://salty-cliffs-06856.herokuapp.com"));
client.println(F("Connection: close"));
Serial.println(F("Done"));
if (client.println() == 0) {
Serial.println(F("Failed to send request"));
return;
}
// Check HTTP status
char status[32] = {0};
client.readBytesUntil('\r', status, sizeof(status));
Serial.println(status);
if (strcmp(status, "HTTP/1.1 200 OK") != 0) {
Serial.print(F("Unexpected response: "));
Serial.println(status);
return;
}
// Skip HTTP headers
char endOfHeaders[] = "\r\n\r\n";
if (!client.find(endOfHeaders)) {
Serial.println(F("Invalid response"));
return;
}
// Allocate JsonBuffer
// Use arduinojson.org/assistant to compute the capacity.
const size_t capacity = JSON_OBJECT_SIZE(3) + JSON_ARRAY_SIZE(2) + 60;
DynamicJsonBuffer jsonBuffer(capacity);
// Parse JSON object
JsonObject& root = jsonBuffer.parseObject(client);
if (!root.success()) {
Serial.println(F("Parsing failed!"));
return;
}
// Extract values
Serial.println(F("Response:"));
Serial.println(root["command"].as<char*>());
// Disconnect
client.stop();
Everything was working fine with that code when I was trying putting there non-secured HTTP address. After putting there my web powered by Heroku secrued by HTTPS I always got error.
The program annouced error when I was checking HTTP status and in my Arduino port terminal I got response:
Unexpected response: HTTP/1.1 400 Bad Request
I checked my heroku logs but there are not listed any request from Arduino. (Just to be sure I tried to called API from web browser and it works)
Could you help me where could be a problem ? I was thinking that it could be because of secured HTTPS. What do you think ?
Thanks for every help :)

Answer 1

First, change client.connect("https://salty-cliffs-06856.herokuapp.com", 80)
from
`https`
to
`http`
as port 80 is not https port and Ethernet shield does not support SSL.
Secondly, you have a wrong http header for Host. the HTTP 1.1 requires that only the domain name to use used without the protocol (i.e. http://) prefix. So change the line:
client.println(F("Host: https://salty-cliffs-06856.herokuapp.com"));
to:
client.println(F("Host: salty-cliffs-06856.herokuapp.com"));