I am attempting to send an email triggered by an alarm condition (dry contacts). I need to use dynamic credentials for the WiFi and email since they need to be configured by whoever is installing the device based on the users Wifi and email. Hence, fixed Wifi credentials and email address are not a viable solution. I've found several tutorials on creating dynamic credentials and sending emails and I've been able to implement those with no problems. Where I'm struggling is combining these two applications. I've been focusing on that portion of the project and not so much with the actual event trigger. The problem appears to be with the connection to the email server. The project compiles ok. I'm using a ESP32-C3-DevKitC-02 with platformio, VS Code and the Arduino framework.
Here's the error I get at runtime:
C: ESP Mail Client v1.6.4
C: connect to SMTP server
C: host > smtp.gmail.com
C: port > 465
C: starting socket
[174221][E][WiFiGeneric.cpp:1230] hostByName(): DNS Failed for smtp.gmail.com
! E: could not get ip from host
[174234][E][ESP32_WCS.cpp:193] connect(): startesp32_ssl_client: -1
C: cleaning SSL connection
Error, unable to connect to server
E: unable to connect to server
Connecting to SMTP server...
Heres the code:
#include <Arduino.h>
#include <WiFi.h>
#include <ESPAsyncWebServer.h>
#include <AsyncTCP.h>
#include "SPIFFS.h"
#include <ESP_Mail_Client.h>
// Create AsyncWebServer object on port 80
AsyncWebServer server(80);
// Search for parameter in HTTP POST request
const char* PARAM_INPUT_1 = "ssid";
const char* PARAM_INPUT_2 = "pass";
const char* PARAM_INPUT_3 = "ip";
const char* PARAM_INPUT_4 = "gateway";
#define SMTP_HOST "smtp.gmail.com"
#define SMTP_PORT 465
/* The sign in credentials */
#define AUTHOR_EMAIL "???????????@?????????.com"
#define AUTHOR_PASSWORD "????????????"
/* Recipient's email*/
#define RECIPIENT_EMAIL "???????????@??????.com"
//Variables to save values from HTML form
String ssid;
String pass;
String ip;
String gateway;
// File paths to save input values permanently
const char* ssidPath = "/ssid.txt";
const char* passPath = "/pass.txt";
const char* ipPath = "/ip.txt";
const char* gatewayPath = "/gateway.txt";
IPAddress localIP;
//IPAddress localIP(192, 168, 1, 200); // hardcoded
// Set your Gateway IP address
IPAddress localGateway;
//IPAddress localGateway(192, 168, 1, 1); //hardcoded
IPAddress subnet(255, 255, 0, 0);
// Timer variables
unsigned long previousMillis = 0;
const long interval = 10000; // interval to wait for Wi-Fi connection (milliseconds)
// Set LED GPIO
const int ledPin = 2;
// Stores LED state
String ledState;
// Initialize SPIFFS
void initSPIFFS() {
if (!SPIFFS.begin(true)) {
Serial.println("An error has occurred while mounting SPIFFS");
}
Serial.println("SPIFFS mounted successfully");
}
// Read File from SPIFFS
String readFile(fs::FS &fs, const char * path){
Serial.printf("Reading file: %s\r\n", path);
File file = fs.open(path);
if(!file || file.isDirectory()){
Serial.println("- failed to open file for reading");
return String();
}
String fileContent;
while(file.available()){
fileContent = file.readStringUntil('\n');
break;
}
return fileContent;
}
// Write file to SPIFFS
void writeFile(fs::FS &fs, const char * path, const char * message){
Serial.printf("Writing file: %s\r\n", path);
File file = fs.open(path, FILE_WRITE);
if(!file){
Serial.println("- failed to open file for writing");
return;
}
if(file.print(message)){
Serial.println("- file written");
} else {
Serial.println("- frite failed");
}
}
// Initialize WiFi
bool initWiFi() {
if(ssid=="" || ip==""){
Serial.println("Undefined SSID or IP address.");
return false;
}
WiFi.mode(WIFI_STA);
localIP.fromString(ip.c_str());
localGateway.fromString(gateway.c_str());
if (!WiFi.config(localIP, localGateway, subnet)){
Serial.println("STA Failed to configure");
return false;
}
WiFi.begin(ssid.c_str(), pass.c_str());
Serial.println("Connecting to WiFi...");
unsigned long currentMillis = millis();
previousMillis = currentMillis;
while(WiFi.status() != WL_CONNECTED) {
currentMillis = millis();
if (currentMillis - previousMillis >= interval) {
Serial.println("Failed to connect.");
return false;
}
}
Serial.println(WiFi.localIP());
return true;
}
// Replaces placeholder with LED state value
String processor(const String& var) {
if(var == "STATE") {
if(digitalRead(ledPin)) {
ledState = "ON";
}
else {
ledState = "OFF";
}
return ledState;
}
return String();
}
/* The SMTP Session object used for Email sending */
SMTPSession smtp;
/* Callback function to get the Email sending status */
void smtpCallback(SMTP_Status status);
void setup() {
// Serial port for debugging purposes
Serial.begin(115200);
initSPIFFS();
// Set GPIO 2 as an OUTPUT
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, LOW);
// Load values saved in SPIFFS
ssid = readFile(SPIFFS, ssidPath);
pass = readFile(SPIFFS, passPath);
ip = readFile(SPIFFS, ipPath);
gateway = readFile (SPIFFS, gatewayPath);
Serial.println(ssid);
Serial.println(pass);
Serial.println(ip);
Serial.println(gateway);
if(initWiFi()) {
// Route for root / web page
server.on("/", HTTP_GET, [](AsyncWebServerRequest *request) {
request->send(SPIFFS, "/index.html", "text/html", false, processor);
});
server.serveStatic("/", SPIFFS, "/");
// Route to set GPIO state to HIGH
server.on("/on", HTTP_GET, [](AsyncWebServerRequest *request) {
digitalWrite(ledPin, HIGH);
request->send(SPIFFS, "/index.html", "text/html", false, processor);
});
// Route to set GPIO state to LOW
server.on("/off", HTTP_GET, [](AsyncWebServerRequest *request) {
digitalWrite(ledPin, LOW);
request->send(SPIFFS, "/index.html", "text/html", false, processor);
});
server.begin();
}
else {
// Connect to Wi-Fi network with SSID and password
Serial.println("Setting AP (Access Point)");
// NULL sets an open Access Point
WiFi.softAP("ESP-WIFI-MANAGER", NULL);
IPAddress IP = WiFi.softAPIP();
Serial.print("AP IP address: ");
Serial.println(IP);
// Web Server Root URL
server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){
request->send(SPIFFS, "/wifimanager.html", "text/html");
});
server.serveStatic("/", SPIFFS, "/");
server.on("/", HTTP_POST, [](AsyncWebServerRequest *request) {
int params = request->params();
for(int i=0;i<params;i++){
AsyncWebParameter* p = request->getParam(i);
if(p->isPost()){
// HTTP POST ssid value
if (p->name() == PARAM_INPUT_1) {
ssid = p->value().c_str();
Serial.print("SSID set to: ");
Serial.println(ssid);
// Write file to save value
writeFile(SPIFFS, ssidPath, ssid.c_str());
}
// HTTP POST pass value
if (p->name() == PARAM_INPUT_2) {
pass = p->value().c_str();
Serial.print("Password set to: ");
Serial.println(pass);
// Write file to save value
writeFile(SPIFFS, passPath, pass.c_str());
}
// HTTP POST ip value
if (p->name() == PARAM_INPUT_3) {
ip = p->value().c_str();
Serial.print("IP Address set to: ");
Serial.println(ip);
// Write file to save value
writeFile(SPIFFS, ipPath, ip.c_str());
}
// HTTP POST gateway value
if (p->name() == PARAM_INPUT_4) {
gateway = p->value().c_str();
Serial.print("Gateway set to: ");
Serial.println(gateway);
// Write file to save value
writeFile(SPIFFS, gatewayPath, gateway.c_str());
}
//Serial.printf("POST[%s]: %s\n", p->name().c_str(), p->value().c_str());
}
}
request->send(200, "text/plain", "Done. ESP will restart, connect to your router and go to IP address: " + ip);
delay(3000);
ESP.restart();
});
server.begin();
}
}
void loop() {
/** Enable the debug via Serial port
* none debug or 0
* basic debug or 1
*/
smtp.debug(1);
/* Set the callback function to get the sending results */
smtp.callback(smtpCallback);
/* Declare the session config data */
ESP_Mail_Session session;
/* Set the session config */
session.server.host_name = SMTP_HOST;
session.server.port = SMTP_PORT;
session.login.email = AUTHOR_EMAIL;
session.login.password = AUTHOR_PASSWORD;
session.login.user_domain = "";
/* Declare the message class */
SMTP_Message message;
/* Set the message headers */
message.sender.name = "ESP";
message.sender.email = AUTHOR_EMAIL;
message.subject = "Blackwater Alert";
message.addRecipient("Cliff", RECIPIENT_EMAIL);
/*Send HTML message*/
String htmlMsg = "<div style=\"color:#2f4468;\"><h1>Holy Shit!</h1><p>- Sent from Blackwater Alert</p></div>";
message.html.content = htmlMsg.c_str();
message.html.content = htmlMsg.c_str();
message.text.charSet = "us-ascii";
message.html.transfer_encoding = Content_Transfer_Encoding::enc_7bit;
/*
//Send raw text message
String textMsg = "Hello World! - Sent from ESP board";
message.text.content = textMsg.c_str();
message.text.charSet = "us-ascii";
message.text.transfer_encoding = Content_Transfer_Encoding::enc_7bit;
message.priority = esp_mail_smtp_priority::esp_mail_smtp_priority_low;
message.response.notify = esp_mail_smtp_notify_success | esp_mail_smtp_notify_failure | esp_mail_smtp_notify_delay;*/
/* Set the custom message header */
//message.addHeader("Message-ID: <abcde.fghij@gmail.com>");
/* Connect to server with the session config */
if (!smtp.connect(&session))
return;
/* Start sending Email and close the session */
if (!MailClient.sendMail(&smtp, &message))
Serial.println("Error sending Email, " + smtp.errorReason());
}
/* Callback function to get the Email sending status */
void smtpCallback(SMTP_Status status){
/* Print the current status */
Serial.println(status.info());
/* Print the sending result */
if (status.success()){
Serial.println("----------------");
ESP_MAIL_PRINTF("Message sent success: %d\n", status.completedCount());
ESP_MAIL_PRINTF("Message sent failled: %d\n", status.failedCount());
Serial.println("----------------\n");
struct tm dt;
for (size_t i = 0; i < smtp.sendingResult.size(); i++){
/* Get the result item */
SMTP_Result result = smtp.sendingResult.getItem(i);
time_t ts = (time_t)result.timestamp;
localtime_r(&ts, &dt);
ESP_MAIL_PRINTF("Message No: %d\n", i + 1);
ESP_MAIL_PRINTF("Status: %s\n", result.completed ? "success" : "failed");
ESP_MAIL_PRINTF("Date/Time: %d/%d/%d %d:%d:%d\n", dt.tm_year + 1900, dt.tm_mon + 1, dt.tm_mday, dt.tm_hour, dt.tm_min, dt.tm_sec);
ESP_MAIL_PRINTF("Recipient: %s\n", result.recipients);
ESP_MAIL_PRINTF("Subject: %s\n", result.subject);
}
Serial.println("----------------\n");
}
}
The .ini file:
[env:esp32-c3-devkitm-1]
platform = espressif32
board = esp32-c3-devkitm-1
framework = arduino
monitor_speed = 115200
lib_deps = ESP Async WebServer, mobizt/ESP Mail Client @ ^1.3.0
- This code is based on the tutorials by Rui Santos
Again, the Dynami Wifi Credentials and Email each work correctly on their own. I'd appreciate any help I can get. I've done a fair amount of C programming, though its been several years, I haven't worked with C++.
Regards