Added QR Code logic

HomeSpan now broadcasts a Hashed Setup ID as MDNS "sh", which is used when pairing with a QR Code instead of a Setup Code.  A text version of the resulting QR code is output to the Serial Monitor whenever the 9-digit Setup Code is generated or changed.  The text version of the QR code can then be input into any QR Code Generator to create a pairable QR Code.

The default Setup ID used to create the Hashed Setup ID is "HSPN".  This can be changed with homeSpan.setQRCode(const char *id), where id is exactly 4 alphanumeric characters.  If not, the request to change the Setup ID is silently ignored and remains "HSPN."

src/HAP.cpp

@@ -58,11 +58,14 @@ void HAPClient::init(){
   } else {
     
     char c[128];
-    sprintf(c,"Generating SRP verification data for default Setup Code: %.3s-%.2s-%.3s\n\n",homeSpan.defaultSetupCode,homeSpan.defaultSetupCode+3,homeSpan.defaultSetupCode+5);
+    sprintf(c,"Generating SRP verification data for default Setup Code: %.3s-%.2s-%.3s\n",homeSpan.defaultSetupCode,homeSpan.defaultSetupCode+3,homeSpan.defaultSetupCode+5);
     Serial.print(c);
     srp.createVerifyCode(homeSpan.defaultSetupCode,verifyData.verifyCode,verifyData.salt);         // create verification code from default Setup Code and random salt
     nvs_set_blob(srpNVS,"VERIFYDATA",&verifyData,sizeof(verifyData));                           // update data
-    nvs_commit(srpNVS);                                                                         // commit to NVS    
+    nvs_commit(srpNVS);                                                                         // commit to NVS
+    Serial.print("Optional QR Code: ");
+    Serial.print(homeSpan.getQRCode(homeSpan.defaultSetupCode));
+    Serial.print("\n\n");          
   }
   
   if(!nvs_get_blob(hapNVS,"ACCESSORY",NULL,&len)){                    // if found long-term Accessory data in NVS

src/HomeSpan.cpp

@@ -410,6 +410,17 @@ void Span::checkConnect(){
   else
     mdns_service_txt_item_set("_hap","_tcp","sf","0");           // set Status Flag = 0
 
+  uint8_t hashInput[22];
+  uint8_t hashOutput[64];
+  char setupHash[9];
+  size_t len;
+  
+  memcpy(hashInput,qrID,4);                                           // Create the Seup ID for use with optional QR Codes.  This is an undocumented feature of HAP R2!
+  memcpy(hashInput+4,id,17);                                          // Step 1: Concatenate 4-character Setup ID and 17-character Accessory ID into hashInput
+  mbedtls_sha512_ret(hashInput,21,hashOutput,0);                      // Step 2: Perform SHA-512 hash on combined 21-byte hashInput to create 64-byte hashOutput
+  mbedtls_base64_encode((uint8_t *)setupHash,9,&len,hashOutput,4);    // Step 3: Encode the first 4 bytes of hashOutput in base64, which results in an 8-character, null-terminated, setupHash
+  mdns_service_txt_item_set("_hap","_tcp","sh",setupHash);            // Step 4: broadcast the resulting Setup Hash
+
   Serial.print("\nStarting Web (HTTP) Server supporting up to ");
   Serial.print(maxConnections);
   Serial.print(" simultaneous connections...\n\n");
@@ -426,6 +437,19 @@ void Span::checkConnect(){
 
 ///////////////////////////////
 
+void Span::setQRID(const char *id){
+  
+  char tBuf[5];
+  sscanf(id,"%4[0-9A-Za-z]",tBuf);
+  
+  if(strlen(id)==4 && strlen(tBuf)==4){
+    qrID=id;
+  }
+    
+} // setQRID
+
+///////////////////////////////
+
 void Span::processSerialCommand(const char *c){
 
   switch(c[0]){
@@ -515,6 +539,10 @@ void Span::processSerialCommand(const char *c){
         nvs_set_blob(HAPClient::srpNVS,"VERIFYDATA",&verifyData,sizeof(verifyData));                              // update data
         nvs_commit(HAPClient::srpNVS);                                                                            // commit to NVS
         Serial.print("New Code Saved!\n");
+
+        Serial.print("Optional QR Code: ");
+        Serial.print(getQRCode(setupCode));
+        Serial.print("\n\n");        
       }            
     }
     break;
@@ -725,6 +753,32 @@ void Span::processSerialCommand(const char *c){
 
 ///////////////////////////////
 
+const char *Span::getQRCode(const char *setupCode){
+  
+  uint64_t n;
+  uint64_t iSetupCode;
+  uint64_t iCategory;
+  
+  sscanf(category,"%llu",&iCategory);
+  sscanf(setupCode,"%llu",&iSetupCode);
+  
+  n=(iCategory << 31) | (0xA << 27) | iSetupCode;
+  
+  qrCode="";
+  
+  while(n>0){
+    char c=n%36+48;
+    if(c>57)
+      c+=7;
+    qrCode=c+qrCode;
+    n/=36;
+  }
+  qrCode="X-HM://00" + qrCode + qrID;  
+  return(qrCode.c_str());
+}
+
+///////////////////////////////
+
 int Span::sprintfAttributes(char *cBuf){
 
   int nBytes=0;

src/HomeSpan.h

@@ -85,6 +85,7 @@ struct Span{
   int nFatalErrors=0;                           // number of fatal errors in user-defined configuration
   String configLog;                             // log of configuration process, including any errors
   boolean isBridge=true;                        // flag indicating whether device is configured as a bridge (i.e. first Accessory contains nothing but AccessoryInformation and HAPProtocolInformation)
+  String qrCode;                                // optional QR Code to use for pairing
 
   boolean connected=false;                      // WiFi connection status
   unsigned long waitTime=60000;                 // time to wait (in milliseconds) between WiFi connection attempts
@@ -97,6 +98,7 @@ struct Span{
   uint8_t maxConnections=DEFAULT_MAX_CONNECTIONS;             // number of simultaneous HAP connections
   unsigned long comModeLife=DEFAULT_COMMAND_TIMEOUT*1000;     // length of time (in milliseconds) to keep Command Mode alive before resuming normal operations
   uint16_t tcpPortNum=DEFAULT_TCP_PORT;                       // port for TCP communications between HomeKit and HomeSpan
+  const char *qrID=DEFAULT_QR_ID;                             // optional Setup ID used to pair with QR Code
 
   WiFiServer *hapServer;                            // pointer to the HAP Server connection
   Blinker statusLED;                                // indicates HomeSpan status
@@ -146,6 +148,8 @@ struct Span{
   void setMaxConnections(uint8_t nCon){maxConnections=nCon;}              // sets maximum number of simultaneous HAP connections (HAP requires devices support at least 8)
   void setHostNameSuffix(const char *suffix){hostNameSuffix=suffix;}      // sets the hostName suffix to be used instead of the 6-byte AccessoryID
   void setPortNum(uint16_t port){tcpPortNum=port;}                        // sets the TCP port number to use for communications between HomeKit and HomeSpan
+  void setQRID(const char *id);                                           // sets the Setup ID for optional pairing with a QR Code
+  const char *getQRCode(const char *setupCode);                           // gets an optional QR code from setupCode
 };
 
 ///////////////////////////////

src/SRP.h

@@ -29,6 +29,7 @@
 
 #include <mbedtls/sha512.h>
 #include <mbedtls/bignum.h>
+#include <mbedtls/base64.h>
 
 #include "HAPConstants.h"
 

src/Settings.h

@@ -61,6 +61,8 @@
 
 #define     DEFAULT_SETUP_CODE        "46637726"          // changed during network setup or with 'S' command
 
+#define     DEFAULT_QR_ID             "HSPN"              // change with homeSpan.setQRID(qrID);
+
 #define     DEFAULT_CONTROL_PIN       21                  // change with homeSpan.setControlPin(pin)
 #define     DEFAULT_STATUS_PIN        13                  // change with homeSpan.setStatusPin(pin)
 

src/src.ino

@@ -8,10 +8,7 @@ void setup() {
  
   Serial.begin(115200);
  
-  homeSpan.setLogLevel(2);
+  homeSpan.setLogLevel(1);
-
-  homeSpan.setHostNameSuffix("");
-  homeSpan.setPortNum(1200);
 
   homeSpan.begin(Category::Lighting,"HomeSpanTest");