Remove the use of common buffer (#199)

* Make publish use internal buffers

* Fix comment about packet ID

* Try a different approach for ping and disconnect

* Use writev and flush in conjuction with send

* Update the publish method to use vectors

* Add vectored IO to all functions

* Fix formatting

* Reduce complexity score

* Fix spell check and complexity score

* Fix breaking build

* Add doxygen comments

* Fix doxygen part 2

* Doxygen fix part 3

* Fix doxygen part 4

* Fix some checks

* Fix memory tables

* Fix some small errors

* Fix compiler warnings and breaking CI checks from previous commit

* Fix spell check and doxygen

* Fix a couple of CBMC proofs

* Fix ping and publish proofs

* Update the function name

* Fix more CBMC proofs

* Fix MQTT Connect proof

* Add unwinding loops

* Fix last CBMC proof

* Fix formatting

* Update the Subscribe and Unsubscribe functions

* Fix formatting and doxygen checks

* Fix broken CBMC proofs

* Fix memory statistic table

* Revert changes from serializer source

* update comments to clarify write requirements

* Add a note for write function pointer

* Fix spell check

docs/doxygen/include/size_table.md

@@ -9,8 +9,8 @@
     </tr>
     <tr>
         <td>core_mqtt.c</td>
-        <td><center>3.1K</center></td>
-        <td><center>2.7K</center></td>
+        <td><center>3.8K</center></td>
+        <td><center>3.2K</center></td>
     </tr>
     <tr>
         <td>core_mqtt_state.c</td>
@@ -19,12 +19,12 @@
     </tr>
     <tr>
         <td>core_mqtt_serializer.c</td>
-        <td><center>2.7K</center></td>
-        <td><center>2.1K</center></td>
+        <td><center>2.8K</center></td>
+        <td><center>2.2K</center></td>
     </tr>
     <tr>
         <td><b>Total estimates</b></td>
-        <td><b><center>7.3K</center></b></td>
-        <td><b><center>5.9K</center></b></td>
+        <td><b><center>8.1K</center></b></td>
+        <td><b><center>6.5K</center></b></td>
     </tr>
 </table>

lexicon.txt

@@ -112,7 +112,10 @@ initializeconnectinfo
 initializesubscribeinfo
 initializewillinfo
 int
+io
 iot
+ioveccount
+ip
 isn
 iso
 keepaliveintervalsec
@@ -240,11 +243,13 @@ pingreqs
 pingreqsendtimems
 pingresp
 pingresps
+piovec
 pismatch
 plaintext
 pmatch
 pmessage
 pmqttcontext
+pmqttheader
 pnameindex
 pnetworkbuffer
 pnetworkcontext
@@ -279,10 +284,12 @@ psuback
 psubackpacket
 psubscribeinfo
 psubscribes
+psubscription
 psubscriptionlist
 ptopic
 ptopicfilter
 ptopicname
+ptotalmessagelength
 ptr
 ptransport
 ptransportinterface
@@ -330,6 +337,11 @@ serializeack
 serializeconnect
 serializeconnectpacket
 serializedisconnect
+serailizedlength
+serializedpasswordlength
+serializedpayloadlength
+serializedtopiclength
+serializedusernamelength
 serializepayload
 serializepingreq
 serializepublish
@@ -376,6 +388,7 @@ tlssend
 toolchain
 topicfilterlength
 topicnamelength
+totalmessagelength
 tr
 transportcallback
 transportinterface
@@ -392,6 +405,7 @@ uint
 un
 unsuback
 unsubscribelist
+updatedlength
 updatestateack
 updatestatepublish
 updatestatestatus
@@ -402,6 +416,7 @@ validatesubscribeunsubscribeparams
 validator
 waitingforpingresp
 willinfo
+writev
 xa
 xb
 xc