Properly handle u8 pointers when assigning and comparing (#8818)

* simplify ctors and operator=, use a common code paths instead of special handling here and there
* fix u8->u32 casts, copy before using u8 data
* do not use raw_address() internally

cores/esp8266/IPAddress.cpp

@@ -41,24 +41,14 @@ bool IPAddress::isSet () const {
 }
 
 IPAddress::IPAddress(uint8_t first_octet, uint8_t second_octet, uint8_t third_octet, uint8_t fourth_octet) {
-    setV4();
+    uint8_t addr[] {
-    (*this)[0] = first_octet;
+        first_octet,
-    (*this)[1] = second_octet;
+        second_octet,
-    (*this)[2] = third_octet;
+        third_octet,
-    (*this)[3] = fourth_octet;
+        fourth_octet,
-}
+    };
 
-void IPAddress::ctor32(uint32_t address) {
+    *this = &addr[0];
-    setV4();
-    v4() = address;
-}
-
-IPAddress::IPAddress(const uint8_t *address) {
-    setV4();
-    (*this)[0] = address[0];
-    (*this)[1] = address[1];
-    (*this)[2] = address[2];
-    (*this)[3] = address[3];
 }
 
 bool IPAddress::fromString(const char *address) {
@@ -116,8 +106,10 @@ bool IPAddress::fromString4(const char *address) {
 }
 
 IPAddress& IPAddress::operator=(const uint8_t *address) {
-    setV4();
+    uint32_t value;
-    v4() = *reinterpret_cast<const uint32_t*>(address);
+    memcpy_P(&value, address, sizeof(value));
+
+    *this = value;
     return *this;
 }
 
@@ -128,7 +120,14 @@ IPAddress& IPAddress::operator=(uint32_t address) {
 }
 
 bool IPAddress::operator==(const uint8_t* addr) const {
-    return isV4() && v4() == *reinterpret_cast<const uint32_t*>(addr);
+    if (!isV4()) {
+        return false;
+    }
+
+    uint32_t value;
+    memcpy_P(&value, addr, sizeof(value));
+
+    return v4() == value;
 }
 
 size_t IPAddress::printTo(Print& p) const {

cores/esp8266/IPAddress.h

@@ -61,19 +61,16 @@ class IPAddress: public Printable {
             return reinterpret_cast<const uint8_t*>(&v4());
         }
 
-        void ctor32 (uint32_t);
-
     public:
-        // Constructors
         IPAddress();
         IPAddress(const IPAddress&);
         IPAddress(IPAddress&&);
 
         IPAddress(uint8_t first_octet, uint8_t second_octet, uint8_t third_octet, uint8_t fourth_octet);
-        IPAddress(uint32_t address) { ctor32(address); }
+        IPAddress(uint32_t address) { *this = address; }
-        IPAddress(unsigned long address) { ctor32(address); }
+        IPAddress(unsigned long address) { *this = address; }
-        IPAddress(int address) { ctor32(address); }
+        IPAddress(int address) { *this = address; }
-        IPAddress(const uint8_t *address);
+        IPAddress(const uint8_t *address) { *this = address; }
 
         bool fromString(const char *address);
         bool fromString(const String &address) { return fromString(address.c_str()); }
@@ -88,7 +85,7 @@ class IPAddress: public Printable {
         operator bool ()       { return isSet(); } // <- both are needed
 
         // generic IPv4 wrapper to uint32-view like arduino loves to see it
-        const uint32_t& v4() const { return ip_2_ip4(&_ip)->addr; } // for raw_address(const)
+        const uint32_t& v4() const { return ip_2_ip4(&_ip)->addr; }
               uint32_t& v4()       { return ip_2_ip4(&_ip)->addr; }
 
         bool operator==(const IPAddress& addr) const {
@@ -117,11 +114,18 @@ class IPAddress: public Printable {
 
         // Overloaded index operator to allow getting and setting individual octets of the address
         uint8_t operator[](int index) const {
-            return isV4()? *(raw_address() + index): 0;
+            if (!isV4()) {
+                return 0;
             }
+
+            return ip4_addr_get_byte_val(*ip_2_ip4(&_ip), index);
+        }
+
         uint8_t& operator[](int index) {
             setV4();
-            return *(raw_address() + index);
+
+            uint8_t* ptr = reinterpret_cast<uint8_t*>(&v4());
+            return *(ptr + index);
         }
 
         // Overloaded copy operators to allow initialisation of IPAddress objects from other types