Add SSU LZSS HTTP OTA example

libraries/SSU/examples/SSU_LZSS_HttpOta/SSU_LZSS_HttpOta.ino

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+/*
+    Small example sketch demonstrating how to perform OTA via HTTP/S
+    utilizing a MKRGSM 1400 and the storage on the integrated
+    SARA U-201 GSM module.
+
+    Please, be careful because no verification is done on the
+    received OTA file, apart size verification of the transmitted
+    bytes using the HTTP Content-Length header.
+
+    For production-grade OTA procedure you might want to implement
+    a content verification procedure using a CRC calculation
+    or an hash (eg. MD5 or SHA256) comparison.
+
+    Circuit:
+    * MKR GSM 1400 board
+    * Antenna
+    * SIM card with a data plan
+
+    Steps to update a sketch:
+
+    1) Create a new sketch or update an existing one to be updated over-the-air.
+       The sketch needs to contain also the code below for future OTAs.
+       The sketch must include the SSU library via
+       #include <SSU.h>
+
+    2) In the IDE select: Sketch -> Export compiled Binary.
+
+    3) Open the location of the sketch (Sketch -> Show Sketch Folder) and compress it
+       with a lzss tool
+       (eg. https://github.com/arduino-libraries/ArduinoIoTCloud/blob/master/extras/tools/lzss.py).
+
+    4) Upload the .lzss file to your HTTP/S server.
+
+    5) Upload this sketch after configuring the server, port and filename variables.
+
+    The sketch will download the OTA file, store it into the U-201 storage, and
+    will reset the board to trigger the SSU update procedure.
+
+
+    created 25 June 2020
+    by Giampaolo Mancini
+*/
+
+#include <MKRGSM.h>
+
+// This includes triggers the firmware update procedure
+// in the bootloader after reset.
+#include <SSU.h>
+
+// Do not change! SSU will look for these files!
+constexpr char UPDATE_FILE_NAME[] = "UPDATE.BIN.LZSS";
+static constexpr char CHECK_FILE_NAME[] = "UPDATE.OK";
+
+#include "arduino_secrets.h"
+const char PINNUMBER[] = SECRET_PINNUMBER;
+// APN data
+const char GPRS_APN[] = SECRET_GPRS_APN;
+const char GPRS_LOGIN[] = SECRET_GPRS_LOGIN;
+const char GPRS_PASSWORD[] = SECRET_GPRS_PASSWORD;
+
+// Change to GSMClient for non-SSL/TLS connection.
+// Not recommended.
+GSMSSLClient client;
+GPRS gprs;
+GSM gsmAccess;
+
+GSMFileUtils fileUtils;
+
+bool isHeaderComplete = false;
+String httpHeader;
+
+bool isDownloadComplete = false;
+unsigned int fileSize = 0;
+unsigned int totalWritten = 0;
+
+constexpr char server[] = "example.org";
+constexpr int port = 443;
+
+// Name of the new firmware file to be updated.
+constexpr char filename[] = "update.lzss";
+
+
+void setup()
+{
+    unsigned long timeout = millis();
+
+    Serial.begin(9600);
+    while (!Serial && millis() - timeout < 5000)
+        ;
+
+    Serial.println("Starting OTA Update via HTTP and Arduino SSU.");
+    Serial.println();
+
+    bool connected = false;
+
+    Serial.print("Connecting to cellular network... ");
+    while (!connected) {
+        if ((gsmAccess.begin(PINNUMBER) == GSM_READY) && (gprs.attachGPRS(GPRS_APN, GPRS_LOGIN, GPRS_PASSWORD) == GPRS_READY)) {
+            connected = true;
+        } else {
+            Serial.println("Not connected");
+            delay(1000);
+        }
+    }
+
+    Serial.println("Connected.");
+    Serial.println();
+
+    // Modem has already been initialized in the sketch:
+    // begin FileUtils without MODEM initialization.
+    fileUtils.begin(false);
+
+    Serial.print("Connecting to ");
+    Serial.print(server);
+    Serial.print(":");
+    Serial.print(port);
+    Serial.print("... ");
+    if (client.connect(server, port)) {
+        Serial.println("Connected.");
+        Serial.print("Downloading ");
+        Serial.println(filename);
+        Serial.print("... ");
+        // Make the HTTP request:
+        client.print("GET /");
+        client.print(filename);
+        client.println(" HTTP/1.1");
+        client.print("Host: ");
+        client.println(server);
+        client.println("Connection: close");
+        client.println();
+    } else {
+        Serial.println("Connection failed");
+    }
+}
+
+void loop()
+{
+    while (client.available()) {
+        // Skip the HTTP header
+        if (!isHeaderComplete) {
+            const char c = client.read();
+            httpHeader += c;
+            if (httpHeader.endsWith("\r\n\r\n")) {
+                isHeaderComplete = true;
+
+                // Get the size of the OTA file from the
+                // HTTP Content-Length header.
+                fileSize = getContentLength();
+
+                Serial.println();
+                Serial.print("HTTP header complete. ");
+                Serial.print("OTA file size is ");
+                Serial.print(fileSize);
+                Serial.println(" bytes.");
+                if (fileSize == 0) {
+                    Serial.println("Unable to get OTA file size.");
+                    while (true)
+                        ;
+                }
+            }
+        } else {
+            // Read the OTA file in len-bytes blocks to preserve RAM.
+            constexpr size_t len { 512 };
+            char buf[len] { 0 };
+
+            // Read len bytes from HTTP client...
+            uint32_t read = client.readBytes(buf, len);
+            // and append them to the update file.
+            uint32_t written = fileUtils.appendFile(UPDATE_FILE_NAME, buf, read);
+
+            if (written != read) {
+                Serial.println("Error while saving data.");
+                while (true)
+                    ;
+            }
+
+            // Update the received byte counter
+            totalWritten += written;
+
+            // Check for full file received and stored
+            isDownloadComplete = totalWritten == fileSize;
+
+            Serial.print("Received: ");
+            Serial.print(totalWritten);
+            Serial.print("/");
+            Serial.println(fileSize);
+        }
+    }
+    if (isDownloadComplete) {
+        Serial.println();
+        Serial.println("Download complete.");
+        Serial.println("Enabling checkpoint.");
+        Serial.println();
+
+        // Create the checkpoint file: will be removed by SSU
+        // after successful update.
+        auto status = fileUtils.downloadFile(CHECK_FILE_NAME, { 0 }, 1);
+        if (status != 1) {
+            Serial.println("Unable to create checkpoint file.");
+            while (true)
+                ;
+        }
+
+        Serial.println("Resetting MCU in order to trigger SSU...");
+        Serial.println();
+        delay(500);
+        NVIC_SystemReset();
+    }
+}
+
+int getContentLength()
+{
+    const String contentLengthHeader = "Content-Length:";
+    const auto contentLengthHeaderLen = contentLengthHeader.length();
+
+    auto indexContentLengthStart = httpHeader.indexOf(contentLengthHeader);
+    if (indexContentLengthStart < 0) {
+        Serial.println("Unable to find Content-Length header (Start)");
+        return 0;
+    }
+    auto indexContentLengthStop = httpHeader.indexOf("\r\n", indexContentLengthStart);
+    if (indexContentLengthStart < 0) {
+        Serial.println("Unable to find Content-Length header (Stop)");
+        return 0;
+    }
+    auto contentLength = httpHeader.substring(indexContentLengthStart + contentLengthHeaderLen + 1, indexContentLengthStop);
+
+    contentLength.trim();
+    return contentLength.toInt();
+}

libraries/SSU/examples/SSU_LZSS_HttpOta/arduino_secrets.h

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+#define SECRET_PINNUMBER     ""
+#define SECRET_GPRS_APN      "GPRS_APN" // replace your GPRS APN
+#define SECRET_GPRS_LOGIN    "login"    // replace with your GPRS login
+#define SECRET_GPRS_PASSWORD "password" // replace with your GPRS password