Add proper type for variable byte int

For the coming MQTT5 support, I'll need this a lot.

Add proper type for variable byte int
For the coming MQTT5 support, I'll need this a lot.
Wiebe Cazemier
1 parent ecb60b48
Showing 6 changed files with 63 additions and 46 deletions
CMakeLists.txt
FlashMQTests/FlashMQTests.pro
mqttpacket.cpp
mqttpacket.h
variablebyteint.cpp
variablebyteint.h
@@ -59,6 +59,7 @@ add_executable(FlashMQ
     threadglobals.h
     threadloop.h
     publishcopyfactory.h
+    variablebyteint.h
     mainapp.cpp
     main.cpp
@@ -97,6 +98,7 @@ add_executable(FlashMQ
     threadglobals.cpp
     threadloop.cpp
     publishcopyfactory.cpp
+    variablebyteint.cpp
     )
@@ -50,6 +50,7 @@ SOURCES +=  tst_maintests.cpp \
     ../threadglobals.cpp \
     ../threadloop.cpp \
     ../publishcopyfactory.cpp \
+    ../variablebyteint.cpp \
     mainappthread.cpp \
     twoclienttestcontext.cpp
@@ -92,6 +93,7 @@ HEADERS += \
     ../threadglobals.h \
     ../threadloop.h \
     ../publishcopyfactory.h \
+    ../variablebyteint.h \
     mainappthread.h \
     twoclienttestcontext.h
@@ -24,11 +24,6 @@ License along with FlashMQ. If not, see &lt;https://www.gnu.org/licenses/&gt;.
 #include "utils.h"
 #include "threadglobals.h"
-RemainingLength::RemainingLength()
-{
-    memset(bytes, 0, 4);
-}
-
 // constructor for parsing incoming packets
 MqttPacket::MqttPacket(CirBuf &buf, size_t packet_len, size_t fixed_header_length, std::shared_ptr<Client> &sender) :
     bites(packet_len),
@@ -760,27 +755,7 @@ void MqttPacket::handlePubComp()
 void MqttPacket::calculateRemainingLength()
 {
     assert(fixed_header_length == 0); // because you're not supposed to call this on packet that we already know the length of.
-
-    size_t x = bites.size();
-
-    do
-    {
-        if (remainingLength.len > 4)
-            throw std::runtime_error("Calculated remaining length is longer than 4 bytes.");
-
-        char encodedByte = x % 128;
-        x = x / 128;
-        if (x > 0)
-            encodedByte = encodedByte | 128;
-        remainingLength.bytes[remainingLength.len++] = encodedByte;
-    }
-    while(x > 0);
-}
-
-RemainingLength MqttPacket::getRemainingLength() const
-{
-    assert(remainingLength.len > 0);
-    return remainingLength;
+    this->remainingLength = bites.size();
 }
 void MqttPacket::setPacketId(uint16_t packet_id)
@@ -846,7 +821,7 @@ size_t MqttPacket::getSizeIncludingNonPresentHeader() const
     if (fixed_header_length == 0)
     {
         total++;
-        total += remainingLength.len;
+        total += remainingLength.getLen();
     }
     return total;
@@ -899,11 +874,6 @@ bool MqttPacket::containsFixedHeader() const
     return fixed_header_length > 0;
 }
-char MqttPacket::getFirstByte() const
-{
-    return first_byte;
-}
-
 char *MqttPacket::readBytes(size_t length)
 {
     if (pos + length > bites.size())
@@ -991,11 +961,9 @@ void MqttPacket::readIntoBuf(CirBuf &amp;buf) const
     if (!containsFixedHeader())
     {
-        assert(remainingLength.len > 0);
-
-        buf.headPtr()[0] = getFirstByte();
+        buf.headPtr()[0] = first_byte;
         buf.advanceHead(1);
-        buf.write(remainingLength.bytes, remainingLength.len);
+        remainingLength.readIntoBuf(buf);
     }
     else
     {
@@ -33,13 +33,7 @@ License along with FlashMQ. If not, see &lt;https://www.gnu.org/licenses/&gt;.
 #include "logger.h"
 #include "mainapp.h"
-struct RemainingLength
-{
-    char bytes[4];
-    int len = 0;
-public:
-    RemainingLength();
-};
+#include "variablebyteint.h"
 class MqttPacket
 {
@@ -51,7 +45,7 @@ class MqttPacket
     std::vector<std::string> subtopics;
     std::vector<char> bites;
     size_t fixed_header_length = 0; // if 0, this packet does not contain the bytes of the fixed header.
-    RemainingLength remainingLength;
+    VariableByteInt remainingLength;
     char qos = 0;
     std::shared_ptr<Client> sender;
     char first_byte = 0;
@@ -115,8 +109,6 @@ public:
     std::shared_ptr<Client> getSender() const;
     void setSender(const std::shared_ptr<Client> &value);
     bool containsFixedHeader() const;
-    char getFirstByte() const;
-    RemainingLength getRemainingLength() const;
     void setPacketId(uint16_t packet_id);
     uint16_t getPacketId() const;
     void setDuplicate();
+#include "variablebyteint.h"
+
+#include <cassert>
+#include <cstring>
+#include <stdexcept>
+
+void VariableByteInt::readIntoBuf(CirBuf &buf) const
+{
+    assert(len > 0);
+    buf.write(bytes, len);
+}
+
+VariableByteInt &VariableByteInt::operator=(uint32_t x)
+{
+    if (x > 268435455)
+        throw std::runtime_error("Value of variable byte int to encode too big. Bug or corrupt packet?");
+
+    len = 0;
+
+    do
+    {
+        uint8_t encodedByte = x % 128;
+        x = x / 128;
+        if (x > 0)
+            encodedByte = encodedByte | 128;
+        bytes[len++] = encodedByte;
+    }
+    while(x > 0);
+
+    return *this;
+}
+
+uint8_t VariableByteInt::getLen() const
+{
+    return len;
+}
+#ifndef VARIABLEBYTEINT_H
+#define VARIABLEBYTEINT_H
+
+#include "cirbuf.h"
+
+class VariableByteInt
+{
+    char bytes[4];
+    uint8_t len = 0;
+
+public:
+    void readIntoBuf(CirBuf &buf) const;
+    VariableByteInt &operator=(uint32_t x);
+    uint8_t getLen() const;
+};
+
+#endif // VARIABLEBYTEINT_H