From 3aa545688182333ed3f1da26f4582d58c2f11ede Mon Sep 17 00:00:00 2001
From: Gregg <homespan@icloud.com>
Date: Sat, 2 Jan 2021 21:18:50 -0600
Subject: [PATCH] Fixed memory problem with sendEncrypyted()

Switched from using fixed buffer, httpBuf, to a TempBuffer to allow for dynamic allocation of memory when assembling and transmitting large blocks of data.  This was causing a memory overflow of the static httpBuf when responding to a getAccessories() request for a large number of Accessories.
---
 src/HAP.cpp | 24 ++++++++++++++++--------
 src/Utils.h |  8 +++++++-
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/src/HAP.cpp b/src/HAP.cpp
index b351467..150a8df 100644
--- a/src/HAP.cpp
+++ b/src/HAP.cpp
@@ -1381,10 +1381,18 @@ void HAPClient::sendEncrypted(char *body, uint8_t *dataBuf, int dataLen){
   int count=0;
   unsigned long long nBytes;
 
-  httpBuf[count]=bodyLen%256;         // store number of bytes in first frame that encrypts the Body (AAD bytes)
-  httpBuf[count+1]=bodyLen/256;
+  int totalBytes=2+bodyLen+16;                            // 2-byte AAD + bodyLen + 16-byte authentication tag
+  totalBytes+=(dataLen/FRAME_SIZE)*(2+FRAME_SIZE+16);     // number of full frames * size of full frame with 2-byte AAD + 16-byte authentication tag
+
+  if(dataLen%FRAME_SIZE)                                  // if there is a residual last partial frame
+    totalBytes+=2+dataLen%FRAME_SIZE+16;                  // 2-byte AAD + residual of last partial frame + 16-byte authentication tag
+
+  TempBuffer <uint8_t> tBuf(totalBytes);
   
-  crypto_aead_chacha20poly1305_ietf_encrypt(httpBuf+count+2,&nBytes,(uint8_t *)body,bodyLen,httpBuf+count,2,NULL,a2cNonce.get(),a2cKey);   // encrypt the Body with authentication tag appended
+  tBuf.buf[count]=bodyLen%256;         // store number of bytes in first frame that encrypts the Body (AAD bytes)
+  tBuf.buf[count+1]=bodyLen/256;
+  
+  crypto_aead_chacha20poly1305_ietf_encrypt(tBuf.buf+count+2,&nBytes,(uint8_t *)body,bodyLen,tBuf.buf+count,2,NULL,a2cNonce.get(),a2cKey);   // encrypt the Body with authentication tag appended
 
   a2cNonce.inc();                 // increment nonce
   
@@ -1397,17 +1405,17 @@ void HAPClient::sendEncrypted(char *body, uint8_t *dataBuf, int dataLen){
     if(n>FRAME_SIZE)           // maximum number of bytes to encrypt=FRAME_SIZE
       n=FRAME_SIZE;                                     
     
-    httpBuf[count]=n%256;    // store number of bytes that encrypts this frame (AAD bytes)
-    httpBuf[count+1]=n/256;
+    tBuf.buf[count]=n%256;    // store number of bytes that encrypts this frame (AAD bytes)
+    tBuf.buf[count+1]=n/256;
 
-    crypto_aead_chacha20poly1305_ietf_encrypt(httpBuf+count+2,&nBytes,dataBuf+i,n,httpBuf+count,2,NULL,a2cNonce.get(),a2cKey);   // encrypt the next portion of dataBuf with authentication tag appended
+    crypto_aead_chacha20poly1305_ietf_encrypt(tBuf.buf+count+2,&nBytes,dataBuf+i,n,tBuf.buf+count,2,NULL,a2cNonce.get(),a2cKey);   // encrypt the next portion of dataBuf with authentication tag appended
 
     a2cNonce.inc();            // increment nonce
 
     count+=2+n+16;             // increment count by 2-byte AAD record + length of JSON + 16-byte authentication tag
   }
-    
-  client.write(httpBuf,count);   // transmit all encrypted frames to Client
+ 
+  client.write(tBuf.buf,count);   // transmit all encrypted frames to Client
 
   LOG2("-------- SENT ENCRYPTED! --------\n");
       
diff --git a/src/Utils.h b/src/Utils.h
index cfd4de9..c311297 100644
--- a/src/Utils.h
+++ b/src/Utils.h
@@ -48,7 +48,13 @@ struct TempBuffer {
   
   TempBuffer(size_t len){
     nBytes=len*sizeof(bufType);
-    buf=(bufType *)heap_caps_malloc(nBytes,MALLOC_CAP_8BIT);      
+    buf=(bufType *)heap_caps_malloc(nBytes,MALLOC_CAP_8BIT);
+    if(buf==NULL){
+      Serial.print("\n\n*** FATAL ERROR: Requested allocation of ");
+      Serial.print(nBytes);
+      Serial.print(" bytes failed.  Program Halting.\n\n");
+      while(1);
+    }
    }
 
   ~TempBuffer(){