STM32: ethernet enc28j60 standard (HTTP) e SSL (HTTPS)

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Abbiamo già visto i dispositivi w5500 effettuare una connessione cablata con l’STM32, ora esamineremo l’enc28j60, un dispositivo più economico con poche risorse ma abbastanza stabile e ampiamente diffuso. Cerchiamo anche di aggiungere l’SSL per una connessione sicura.

STM32 ethernet enc28j60 with plain HTTP and SSL HTTPS
STM32 ethernet enc28j60 with plain HTTP and SSL HTTPS

Le connessioni SSL richiedono più risorse, in particolare lo spazio Flash, l’SSLClient 1.6.11 richiede circa 100kb di flash.

Dispositivo

L’ENC28J60-I/SP è un controller Ethernet autonomo con un’interfaccia periferica seriale (SPI) standard del settore. È progettato per fungere da interfaccia di rete Ethernet per qualsiasi controller dotato di SPI. L’ENC28J60 soddisfa tutte le specifiche IEEE 802.3. Incorpora diversi schemi di filtraggio dei pacchetti per limitare i pacchetti in entrata. Fornisce inoltre un modulo DMA interno per un veloce throughput dei dati e il calcolo del checksum assistito da hardware, utilizzato in vari protocolli di rete. La comunicazione con il controller host è implementata tramite un pin di interrupt e SPI, con frequenze di clock fino a 20 MHz. Due pin dedicati vengono utilizzati per il collegamento LED e l’indicazione dell’attività di rete.

  • Pienamente compatibile con le reti 10/100/1000Base-T
  • MAC integrato e PHY 10Base-T
  • Supporta una porta 10Base-T con rilevamento e correzione della polarità
  • Supporta le modalità full e half duplex
  • Ritrasmissione automatica programmabile in caso di collisione
  • Padding programmabile e generazione CRC
  • Rifiuto automatico programmabile di pacchetti errati
  • Interfaccia SPI con velocità di clock fino a 20MHz
  • SRAM a doppia porta di trasmissione/ricezione di pacchetti da 8kB
  • Dimensione del buffer di trasmissione/ricezione configurabile
  • FIFO di ricezione circolare gestita dall’hardware
  • Accesso casuale e sequenziale a livello di byte con incremento automatico
  • Medium Access Controller (MAC) supporta pacchetti unicast, multicast e broadcast

Come ho già detto, questo tipo di dispositivo ha molti fattori di forma e talvolta è stato rilasciato come shield.

Il più comune è quello di taglia media.

enc28j60 ethernet network modules
enc28j60 ethernet network modules

Poi un altro molto usato è la versione mini.

enc28j60 mini ethernet network modules
enc28j60 mini ethernet network modules

Ecco la mai selezione di enc8266 w5500 lite - w5500 - enc26j60 mini - enc26j60 - lan8720

Collegamento

Pinout STM32 STM32F1 STM32F103 STM32F103C8 low resolution
Pinout STM32 STM32F1 STM32F103 STM32F103C8 low resolution
STM32 STM32F401 STM32F401CCU6 pinout low resolution
STM32 STM32F401 STM32F401CCU6 pinout low resolution

Ecco la mia selezione di STM32 STM32F103C8T6 STM32F401 STM32F411 ST-Link v2 ST-Link v2 official

Questo dispositivo utilizza un’interfaccia SPI; per impostazione predefinita, utilizzerò un’interfaccia SPI di base.

STM32F1

STM32F1 ethernet enc26j60 wiring
STM32F1 ethernet enc26j60 wiring

STM32F4

STM32F4 ethernet enc26j60 wiring
STM32F4 ethernet enc26j60 wiring
STM32w5500
PA4CS
PA5SCK
PA6MISO
PA7MOSI
3.3v (meglio con 200mha esterni)VCC
GNDGND

A questo proposito ho usato il 3.3v dell’STM32, ma è meglio se usi un alimentatore esterno come il seguente schema.

Attenzione non tutti i dispositivi hanno così tanti ampere per alimentare il dispositivo, quindi se hai problemi devi aggiungere un alimentatore esterno. Specialmente per STM23F1.

In caso di problemi, provare ad alimentare il dispositivo Ethernet con un alimentatore esterno.

STM32F1

STM32F1 ethernet enc26j60 wiring power supply
STM32F1 ethernet enc26j60 wiring power supply

STM32F4

STM32F4 ethernet enc26j60 wiring power supply
STM32F4 ethernet enc26j60 wiring power supply

Librerie

Esistono molte librerie anche per questo dispositivo, la più famosa è UIPEthernet, ma ora abbiamo dei piccoli problemi con l’integrazione con programmi più innovativi, quindi utilizzeremo EthernetENC, che è completamente compatibile con Arduino Ethernet ed è una versione moderna di UIP.

Arduino IDE esp32 EthernetENC library for enc28j60
Arduino IDE esp32 EthernetENC library for enc28j60

SSLClient

Questa libreria e questo dispositivo non supportano SSL, quindi per queste funzionalità esiste una libreria alternativa denominata SSLClient che necessita di una piccola patch di Ethernet.

SSLClient aggiunge  la funzionalità TLS 1.2  a qualsiasi libreria di rete che implementa l’ interfaccia Arduino Client, comprese le classi Arduino EthernetClient e WiFiClient. L’SSLClient è stato creato per integrare TLS con l’infrastruttura Arduino utilizzando BearSSL come motore TLS sottostante. A differenza  di ArduinoBearSSL , SSLClient è completamente autonomo e non richiede alcun hardware aggiuntivo (a parte una connessione di rete). (cit.)

Arduino esp32 ethernet w5500 SSLClient library manager
Arduino esp32 ethernet w5500 SSLClient library manager

SSLClient con EthernetENC

Ho provato questa libreria con alcune altre librerie e ho notato che UIPEthernet non funzionava, ma EthernetENC funziona correttamente senza fare nulla.

Estensione del buffer

Noto anche che per ottenere una buona stabilità probabilmente devi cambiare qualcosa.

In SSLClient.h devi cambiare questa riga.

SSLClient with EthernetENC

unsigned char m_iobuf[2048];

a

unsigned char m_iobuf[BR_SSL_BUFSIZE_BIDI];

Codice

Ora proviamo a fare una semplice WebRequest con un client nativo. Ma prima scriviamo il codice necessario per la connessione, proviamo a chiedere l’IP al server DHCP e, se fallisce, avviamo una connessione con un IP statico.

Inizializza il dispositivo

Ethernet utilizza l’interfaccia SPI predefinita per impostazione predefinita, quindi prima dobbiamo ser il pin SS corretto (probabilmente non necessario).

    // 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
    Ethernet.init(PA4);

Questa scheda è diversa da LAN8720 (dispositivo predefinito per esp32) e necessita di un indirizzo MAC.

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };

Quindi proviamo a fare una richiesta DHCP.

    if (Ethernet.begin(mac)) { // Dynamic IP setup
        Serial.println("DHCP OK!");
    }

Ma se fallisce, proviamo a stabilire una connessione IP statica con questi parametri

// Set the static IP address to use if the DHCP fails to assign
#define MYIPADDR 192,168,1,28
#define MYIPMASK 255,255,255,0
#define MYDNS 192,168,1,1
#define MYGW 192,168,1,1

ed ecco il codice di connessione

		Serial.println("Failed to configure Ethernet using DHCP");
		// 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.");
		}

		IPAddress ip(MYIPADDR);
		IPAddress dns(MYDNS);
		IPAddress gw(MYGW);
		IPAddress sn(MYIPMASK);
		Ethernet.begin(mac, ip, dns, gw, sn);
		Serial.println("STATIC OK!");

Semplice richiesta HTTP

Prima di tutto, proveremo a fare una semplice richiesta HTTP. Ho scelto un servizio online creato per testare questo tipo di richiesta per fare il test.

Userò un semplice servizio fornito da httpbin.org e puoi utilizzare la stessa API REST in HTTP e HTTPS.

Ricorda che HTTP funziona sulla porta 80 HTTPS su 443, quindi per interrogare l’endpoint sulla porta 443, devi convalidare un certificato.

Per stabilire la nostra connessione, utilizziamo l’EthernetClient di base.

// Initialize the Ethernet client library
// with the IP address and port of the server
// that you want to connect to (port 80 is default for HTTP):
EthernetClient client;

E poi, proviamo a connetterci e chiediamo un endpoint GET.

  // if you get a connection, report back via serial:
  if (client.connect(server, 80)) {
    Serial.println("Connected!");
    // Make a HTTP request:
    client.println("GET /get HTTP/1.1");
    client.println("Host: httpbin.org");
    client.println("Connection: close");
    client.println();
  } else {
    // if you didn't get a connection to the server:
    Serial.println("connection failed");
  }

Nel ciclo, attendi una risposta dal server.

  // if there are incoming bytes available
  // from the server, read them and print them:
  int len = client.available();

E poi leggi la risposta e mettila sull’uscita seriale.

  if (len > 0) {
    byte buffer[80];
    if (len > 80) len = 80;
    client.read(buffer, len);
    if (printWebData) {
      Serial.write(buffer, len); // show in the serial monitor (slows some boards)
    }
    byteCount = byteCount + len;
  }

  // if the server's disconnected, stop the client:
  if (!client.connected()) {
    endMicros = micros();
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();
    Serial.print("Received ");
    Serial.print(byteCount);
    Serial.print(" bytes in ");
    float seconds = (float)(endMicros - beginMicros) / 1000000.0;
    Serial.print(seconds, 4);
    float rate = (float)byteCount / seconds / 1000.0;
    Serial.print(", rate = ");
    Serial.print(rate);
    Serial.print(" kbytes/second");
    Serial.println();

    // do nothing forevermore:
    while (true) {
      delay(1);
    }
  }

E per finire, lo sketch completo.

/*
 Web client with enc28j60 and EthernetENC

 This sketch connects to a test website (httpbin.org)
 and try to do a GET request, the output is printed
 on Serial

 by Renzo Mischianti <www.mischianti.org>

 https://www.mischianti.org

 */

#include <SPI.h>
#include <EthernetENC.h>

// if you don't want to use DNS (and reduce your sketch size)
// use the numeric IP instead of the name for the server:
//IPAddress server(74,125,232,128);  // numeric IP for Google (no DNS)
//char server[] = "www.google.com";    // name address for Google (using DNS)
char server[] = "httpbin.org";    // name address for Google (using DNS)

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };

// Set the static IP address to use if the DHCP fails to assign
#define MYIPADDR 192,168,1,28
#define MYIPMASK 255,255,255,0
#define MYDNS 192,168,1,1
#define MYGW 192,168,1,1

// Initialize the Ethernet client library
// with the IP address and port of the server
// that you want to connect to (port 80 is default for HTTP):
EthernetClient client;

// Variables to measure the speed
unsigned long beginMicros, endMicros;
unsigned long byteCount = 0;
bool printWebData = true;  // set to false for better speed measurement

void setup() {
    Serial.begin(115200);
    delay(1000);
    Serial.println("Begin Ethernet");

    // 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
    Ethernet.init(PA4);

    if (Ethernet.begin(mac)) { // Dynamic IP setup
        Serial.println("DHCP OK!");
    }else{
        Serial.println("Failed to configure Ethernet using DHCP");
        // 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.");
        }

    	  IPAddress ip(MYIPADDR);
    	  IPAddress dns(MYDNS);
    	  IPAddress gw(MYGW);
    	  IPAddress sn(MYIPMASK);
    	  Ethernet.begin(mac, ip, dns, gw, sn);
		  Serial.println("STATIC OK!");
    }
    delay(5000);


    Serial.print("Local IP : ");
    Serial.println(Ethernet.localIP());
    Serial.print("Subnet Mask : ");
    Serial.println(Ethernet.subnetMask());
    Serial.print("Gateway IP : ");
    Serial.println(Ethernet.gatewayIP());
    Serial.print("DNS Server : ");
    Serial.println(Ethernet.dnsServerIP());

   Serial.println("Ethernet Successfully Initialized");
  // if you get a connection, report back via serial:
  if (client.connect(server, 80)) {
    Serial.println("Connected!");
    // Make a HTTP request:
    client.println("GET /get HTTP/1.1");
    client.println("Host: httpbin.org");
    client.println("Connection: close");
    client.println();
  } else {
    // if you didn't get a connection to the server:
    Serial.println("connection failed");
  }
  beginMicros = micros();
}

void loop() {
  // if there are incoming bytes available
  // from the server, read them and print them:
  int len = client.available();
  if (len > 0) {
    byte buffer[80];
    if (len > 80) len = 80;
    client.read(buffer, len);
    if (printWebData) {
      Serial.write(buffer, len); // show in the serial monitor (slows some boards)
    }
    byteCount = byteCount + len;
  }

  // if the server's disconnected, stop the client:
  if (!client.connected()) {
    endMicros = micros();
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();
    Serial.print("Received ");
    Serial.print(byteCount);
    Serial.print(" bytes in ");
    float seconds = (float)(endMicros - beginMicros) / 1000000.0;
    Serial.print(seconds, 4);
    float rate = (float)byteCount / seconds / 1000.0;
    Serial.print(", rate = ");
    Serial.print(rate);
    Serial.print(" kbytes/second");
    Serial.println();

    // do nothing forevermore:
    while (true) {
      delay(1);
    }
  }
}

Il risultato è questo.

Begin Ethernet
DHCP OK!
Local IP : 192.168.1.138
Subnet Mask : 255.255.255.0
Gateway IP : 192.168.1.1
DNS Server : 192.168.1.1
Ethernet Successfully Initialized

Connected!
HTTP/1.1 200 OK 
Date: Wed, 09 Mar 2022 11:15:49 GMT
Content-Type: application/json 
Content-Length: 197
Connection: close
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true

{
  "args": {}, 
  "headers": {
    "Host": "httpbin.org", 
    "X-Amzn-Trace-Id": "Root=1-62288c65-1fe4f19070d3ab7c773aee09"
  }, 
  "origin": "82.51.127.46", 
  "url": "http://httpbin.org/get"
}

disconnecting.
Received 422 bytes in 0.2663, rate = 1.58 kbytes/second

Richiesta HTTPS

STM32F4 ethernet enc28j60 mini
STM32F4 ethernet enc28j60 mini

Ora, se cambiamo l’endpoint sulla porta 443, richiederemo un server sicuro con crittografia SSL.

  if (client.connect(server, 443)) {
    Serial.println("Connected!");
    // Make a HTTP request:
    client.println("GET /get HTTP/1.1");
    client.println("Host: httpbin.org");
    client.println("Connection: close");
    client.println();
  } else {
    // if you didn't get a connection to the server:
    Serial.println("connection failed");
  }

E otteniamo questa risposta.

Begin Ethernet
DHCP OK!
Local IP : 192.168.1.138
Subnet Mask : 255.255.255.0
Gateway IP : 192.168.1.1
DNS Server : 192.168.1.1
Ethernet Successfully Initialized
 
Connected!
HTTP/1.1 400 Bad Request
Server: awselb/2.0
Date: Wed, 09 Mar 2022 11:23:16 GMT
Content-Type: text/html
Content-Length: 220
Connection: close

<html>
<head><title>400 The plain HTTP request was sent to HTTPS port</title></head>
<body>
<center><h1>400 Bad Request</h1></center>
<center>The plain HTTP request was sent to HTTPS port</center>
</body>
</html>

Disconnecting.
Received 370 bytes in 0.4333, rate = 0.85 kbytes/second

Quindi il problema è che i messaggi di richiesta e risposta non vengono trasmessi utilizzando SSL (Secure Sockets Layer) o il suo successore TLS (Transport Layer Security). Per aggiungere questa funzione, utilizzeremo SSLClient.

Recupera il certificato

Per utilizzare un SSL, abbiamo bisogno del certificato del server, ma in questo caso l’SSLClient utilizza un trucco fornito dall’implementazione di BearSSL. Questo motore di verifica x509 minimo consente l’utilizzo di un Trust Anchors.

Aggiungo un semplice generatore online che puoi trovare qui .

Devi solo scrivere l’indirizzo del sito (httpbin.org) nella prima casella di input, fare clic su Generate code, copiare il codice e inserirlo in un file chiamato trust_anchors.h e metterlo nella cartella dello sketch.

BearSSL certificate trust anchor retriever online

Ecco il contenuto del trust_anchors.h.

#ifndef _CERTIFICATES_H_
#define _CERTIFICATES_H_

#ifdef __cplusplus
extern "C"
{
#endif

/* This file is auto-generated by the pycert_bearssl tool.  Do not change it manually.
 * Certificates are BearSSL br_x509_trust_anchor format.  Included certs:
 *
 * Index:    0
 * Label:    Starfield Class 2 Certification Authority
 * Subject:  OU=Starfield Class 2 Certification Authority,O=Starfield Technologies\, Inc.,C=US
 * Domain(s): httpbin.org
 */

#define TAs_NUM 1

static const unsigned char TA_DN0[] = {
    0x30, 0x68, 0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04, 0x06, 0x13,
    0x02, 0x55, 0x53, 0x31, 0x25, 0x30, 0x23, 0x06, 0x03, 0x55, 0x04, 0x0a,
    0x13, 0x1c, 0x53, 0x74, 0x61, 0x72, 0x66, 0x69, 0x65, 0x6c, 0x64, 0x20,
    0x54, 0x65, 0x63, 0x68, 0x6e, 0x6f, 0x6c, 0x6f, 0x67, 0x69, 0x65, 0x73,
    0x2c, 0x20, 0x49, 0x6e, 0x63, 0x2e, 0x31, 0x32, 0x30, 0x30, 0x06, 0x03,
    0x55, 0x04, 0x0b, 0x13, 0x29, 0x53, 0x74, 0x61, 0x72, 0x66, 0x69, 0x65,
    0x6c, 0x64, 0x20, 0x43, 0x6c, 0x61, 0x73, 0x73, 0x20, 0x32, 0x20, 0x43,
    0x65, 0x72, 0x74, 0x69, 0x66, 0x69, 0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e,
    0x20, 0x41, 0x75, 0x74, 0x68, 0x6f, 0x72, 0x69, 0x74, 0x79,
};

static const unsigned char TA_RSA_N0[] = {
    0xb7, 0x32, 0xc8, 0xfe, 0xe9, 0x71, 0xa6, 0x04, 0x85, 0xad, 0x0c, 0x11,
    0x64, 0xdf, 0xce, 0x4d, 0xef, 0xc8, 0x03, 0x18, 0x87, 0x3f, 0xa1, 0xab,
    0xfb, 0x3c, 0xa6, 0x9f, 0xf0, 0xc3, 0xa1, 0xda, 0xd4, 0xd8, 0x6e, 0x2b,
    0x53, 0x90, 0xfb, 0x24, 0xa4, 0x3e, 0x84, 0xf0, 0x9e, 0xe8, 0x5f, 0xec,
    0xe5, 0x27, 0x44, 0xf5, 0x28, 0xa6, 0x3f, 0x7b, 0xde, 0xe0, 0x2a, 0xf0,
    0xc8, 0xaf, 0x53, 0x2f, 0x9e, 0xca, 0x05, 0x01, 0x93, 0x1e, 0x8f, 0x66,
    0x1c, 0x39, 0xa7, 0x4d, 0xfa, 0x5a, 0xb6, 0x73, 0x04, 0x25, 0x66, 0xeb,
    0x77, 0x7f, 0xe7, 0x59, 0xc6, 0x4a, 0x99, 0x25, 0x14, 0x54, 0xeb, 0x26,
    0xc7, 0xf3, 0x7f, 0x19, 0xd5, 0x30, 0x70, 0x8f, 0xaf, 0xb0, 0x46, 0x2a,
    0xff, 0xad, 0xeb, 0x29, 0xed, 0xd7, 0x9f, 0xaa, 0x04, 0x87, 0xa3, 0xd4,
    0xf9, 0x89, 0xa5, 0x34, 0x5f, 0xdb, 0x43, 0x91, 0x82, 0x36, 0xd9, 0x66,
    0x3c, 0xb1, 0xb8, 0xb9, 0x82, 0xfd, 0x9c, 0x3a, 0x3e, 0x10, 0xc8, 0x3b,
    0xef, 0x06, 0x65, 0x66, 0x7a, 0x9b, 0x19, 0x18, 0x3d, 0xff, 0x71, 0x51,
    0x3c, 0x30, 0x2e, 0x5f, 0xbe, 0x3d, 0x77, 0x73, 0xb2, 0x5d, 0x06, 0x6c,
    0xc3, 0x23, 0x56, 0x9a, 0x2b, 0x85, 0x26, 0x92, 0x1c, 0xa7, 0x02, 0xb3,
    0xe4, 0x3f, 0x0d, 0xaf, 0x08, 0x79, 0x82, 0xb8, 0x36, 0x3d, 0xea, 0x9c,
    0xd3, 0x35, 0xb3, 0xbc, 0x69, 0xca, 0xf5, 0xcc, 0x9d, 0xe8, 0xfd, 0x64,
    0x8d, 0x17, 0x80, 0x33, 0x6e, 0x5e, 0x4a, 0x5d, 0x99, 0xc9, 0x1e, 0x87,
    0xb4, 0x9d, 0x1a, 0xc0, 0xd5, 0x6e, 0x13, 0x35, 0x23, 0x5e, 0xdf, 0x9b,
    0x5f, 0x3d, 0xef, 0xd6, 0xf7, 0x76, 0xc2, 0xea, 0x3e, 0xbb, 0x78, 0x0d,
    0x1c, 0x42, 0x67, 0x6b, 0x04, 0xd8, 0xf8, 0xd6, 0xda, 0x6f, 0x8b, 0xf2,
    0x44, 0xa0, 0x01, 0xab,
};

static const unsigned char TA_RSA_E0[] = {
    0x03,
};

static const br_x509_trust_anchor TAs[] = {
    {
        { (unsigned char *)TA_DN0, sizeof TA_DN0 },
        BR_X509_TA_CA,
        {
            BR_KEYTYPE_RSA,
            { .rsa = {
                (unsigned char *)TA_RSA_N0, sizeof TA_RSA_N0,
                (unsigned char *)TA_RSA_E0, sizeof TA_RSA_E0,
            } }
        }
    },
};

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* ifndef _CERTIFICATES_H_ */

Aggiungi il wrapper SSLClient

Ora aggiungeremo la libreria SSLClient e il file trust_anchors.h.

#include <SPI.h>
#include <EthernetENC.h>
#include <SSLClient.h>
#include "trust_anchors.h"

Quindi applica il wrapper EthernetClient con tutti i riferimenti di Trust Anchors. Il file contiene nomi di array di trust anchor generati  TAs con lunghezza TAs_NUM.

// Choose the analog pin to get semi-random data from for SSL
// Pick a pin that's not connected or attached to a randomish voltage source
const int rand_pin = A5;

// Initialize the SSL client library
// We input an EthernetClient, our trust anchors, and the analog pin
EthernetClient base_client;
SSLClient client(base_client, TAs, (size_t)TAs_NUM, rand_pin);

E cambiamo la porta in 443 (HTTPS).

  // if you get a connection, report back via serial:
  if (client.connect(server, 443)) {
    Serial.print("connected to ");
    // Make a HTTP request:
    client.println("GET /get HTTP/1.1");
    client.println("Host: httpbin.org");
    client.println("Connection: close");
    client.println();
  } else {
    // if you didn't get a connection to the server:
    Serial.println("connection failed");
  }

Ecco lo sketch completo.

/*
 Web SSL client  with enc28j60, 
 EthernetENC and SSLClient

 This sketch connects to a test website (httpbin.org)
 and try to do a secure GET request on port 443,
 to do the SSL request we use SSLClient with the
 site Trust Anchor
 the output is printed on Serial

 by Renzo Mischianti <www.mischianti.org>

 https://www.mischianti.org

 */

#include <SPI.h>
#include <EthernetENC.h>
#include <SSLClient.h>
#include "trust_anchors.h"

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };

// if you don't want to use DNS (and reduce your sketch size)
// use the numeric IP instead of the name for the server:
//IPAddress server(74,125,232,128);  // numeric IP for Google (no DNS)
//char server[] = "www.google.com";    // name address for Google (using DNS)
char server[] = "httpbin.org";    // name address for Google (using DNS)

// Set the static IP address to use if the DHCP fails to assign
#define MYIPADDR 192,168,1,28
#define MYIPMASK 255,255,255,0
#define MYDNS 192,168,1,1
#define MYGW 192,168,1,1

// Choose the analog pin to get semi-random data from for SSL
// Pick a pin that's not connected or attached to a randomish voltage source
const int rand_pin = A5;

// Initialize the SSL client library
// We input an EthernetClient, our trust anchors, and the analog pin
EthernetClient base_client;
SSLClient client(base_client, TAs, (size_t)TAs_NUM, rand_pin);

// Variables to measure the speed
unsigned long beginMicros, endMicros;
unsigned long byteCount = 0;
bool printWebData = true;  // set to false for better speed measurement

void setup() {
    Serial.begin(115200);
    delay(1000);
    Serial.println("Begin Ethernet");

    // 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
    Ethernet.init(PA4);

    if (Ethernet.begin(mac)) { // Dynamic IP setup
        Serial.println("DHCP OK!");
    }else{
        Serial.println("Failed to configure Ethernet using DHCP");
        // 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.");
        }

    	  IPAddress ip(MYIPADDR);
    	  IPAddress dns(MYDNS);
    	  IPAddress gw(MYGW);
    	  IPAddress sn(MYIPMASK);
    	  Ethernet.begin(mac, ip, dns, gw, sn);
		  Serial.println("STATIC OK!");
    }
    delay(5000);


    Serial.print("Local IP : ");
    Serial.println(Ethernet.localIP());
    Serial.print("Subnet Mask : ");
    Serial.println(Ethernet.subnetMask());
    Serial.print("Gateway IP : ");
    Serial.println(Ethernet.gatewayIP());
    Serial.print("DNS Server : ");
    Serial.println(Ethernet.dnsServerIP());

   Serial.println("Ethernet Successfully Initialized");
  // if you get a connection, report back via serial:
  if (client.connect(server, 443)) {
    Serial.print("connected to ");
    // Make a HTTP request:
    client.println("GET /get HTTP/1.1");
    client.println("Host: httpbin.org");
    client.println("Connection: close");
    client.println();
  } else {
    // if you didn't get a connection to the server:
    Serial.println("connection failed");
  }
  beginMicros = micros();
}

void loop() {
  // if there are incoming bytes available
  // from the server, read them and print them:
  int len = client.available();
  if (len > 0) {
    byte buffer[80];
    if (len > 80) len = 80;
    client.read(buffer, len);
    if (printWebData) {
      Serial.write(buffer, len); // show in the serial monitor (slows some boards)
    }
    byteCount = byteCount + len;
  }

  // if the server's disconnected, stop the client:
  if (!client.connected()) {
    endMicros = micros();
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();
    Serial.print("Received ");
    Serial.print(byteCount);
    Serial.print(" bytes in ");
    float seconds = (float)(endMicros - beginMicros) / 1000000.0;
    Serial.print(seconds, 4);
    float rate = (float)byteCount / seconds / 1000.0;
    Serial.print(", rate = ");
    Serial.print(rate);
    Serial.print(" kbytes/second");
    Serial.println();

    // do nothing forevermore:
    while (true) {
      delay(1);
    }
  }
}

Ora, quando eseguiamo lo sketch, otteniamo questo output.

Begin Ethernet
DHCP OK!
Local IP : 192.168.1.138
Subnet Mask : 255.255.255.0
Gateway IP : 192.168.1.1
DNS Server : 192.168.1.1
Ethernet Successfully Initialized

connected to HTTP/1.1 200 OK
Date: Fri, 11 Mar 2022 10:09:27 GMT
Content-Type: application/json
Content-Length: 200
Connection: close
Server: gunicorn/19.9.0
Access-Control-Allow-Origin: *
Access-Control-Allow-Credentials: true

{
  "args": {},
  "headers": {
    "Host": "httpbin.org",
    "X-Amzn-Trace-Id": "Root=1-622b1fd7-28dcf8756cb3de2006b7b35d"
  },
  "origin": "95.246.191.228",
  "url": "https://httpbin.org/get"
}
(SSLClient)(SSL_ERROR)(m_update_engine): Error writing to m_client
(SSLClient)(SSL_ERROR)(m_update_engine): 0
(SSLClient)(SSL_WARN)(connected): Socket was dropped unexpectedly (this can be an alternative to 
closing the connection)
(SSLClient)(SSL_ERROR)(connected): Not connected because write error is set
(SSLClient)(SSL_ERROR)(m_print_ssl_error): SSL_CLIENT_WRITE_FAIL
(SSLClient)(SSL_ERROR)(available): SSL engine failed to update.
(SSLClient)(SSL_ERROR)(connected): Not connected because write error is set
(SSLClient)(SSL_ERROR)(m_print_ssl_error): SSL_CLIENT_WRITE_FAIL

disconnecting.
(SSLClient)(SSL_ERROR)(connected): Not connected because write error is set
(SSLClient)(SSL_ERROR)(m_print_ssl_error): SSL_CLIENT_WRITE_FAIL
Received 425 bytes in 0.2203, rate = 1.93 kbytes/second

Il codice genera un errore sulla serial, ma la libreria funziona correttamente.

Grazie

  1. STM32F1 Blue Pill: piedinatura, specifiche e configurazione IDE Arduino (STM32duino e STMicroelectronics)
  2. STM32: programmazione (STM32F1) via USB con bootloader STM32duino
  3. STM32: programmazione (STM32F1 STM32F4) tramite USB con bootloader HID
  4. STM32F4 Black Pill: pinout, specifiche e configurazione IDE Arduino
  5. STM32: ethernet w5500 standard (HTTP) e SSL (HTTPS)
  6. STM32: ethernet enc28j60 standard (HTTP) e SSL (HTTPS)
  7. STM32: WiFiNINA con un ESP32 come WiFi Co-Processor
    1. STM32F1 Blue-pill: shield WiFi (WiFiNINA)
    2. STM32F4 Black-pill: shield WiFi (WiFiNINA)
  8. Come utilizzare la scheda SD con l’stm32 e la libreria SdFat
  9. STM32: memoria flash SPI FAT FS
  10. STM32: RTC interno, sistema orario e backup batteria (VBAT)
  11. STM32 LoRa
  1. STM32 Risparmio energetico
    1. STM32F1 Blue-Pill gestione clock e frequenza
    2. STM32F4 Black-Pill gestione clock e frequenza
    3. Introduzione e framework Arduino vs STM
    4. Libreria LowPower, cablaggio e Idle (STM Sleep).
    5. Sleep, deep sleep, shutdown e consumo energetico
    6. Sveglia da allarme RTC e Seriale
    7. Sveglia da sorgente esterna
    8. Introduzione al dominio di backup e conservazione delle variabili durante il RESET
    9. Registro di backup RTC e conservazione della SRAM

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