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3035239a4e
Previously, pointer casting was used, but this resulted in strict-aliasing warnings:
IPAddress.h: In member function ‘IPAddress::operator uint32_t() const’:
IPAddress.h:46:61: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
operator uint32_t() const { return *((uint32_t*)_address); };
^
IPAddress.h: In member function ‘bool IPAddress::operator==(const IPAddress&) const’:
IPAddress.h:47:81: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
bool operator==(const IPAddress& addr) const { return (*((uint32_t*)_address)) == (*((uint32_t*)addr._address)); };
^
IPAddress.h:47:114: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
bool operator==(const IPAddress& addr) const { return (*((uint32_t*)_address)) == (*((uint32_t*)addr._address)); };
Converting between unrelated types like this is commonly done using a union,
which do not break the strict-aliasing rules. Using that union, inside
IPAddress there is now an attribute _address.bytes for the raw byte
arra, or _address.dword for the uint32_t version.
Since we now have easy access to the uint32_t version, this also removes
two memcpy invocations that can just become assignments.
This patch does not change the generated code in any way, the compiler
already optimized away the memcpy calls and the previous casts mean
exactly the same.
This is a different implementation of a part of #1399 and it helps
toward fixing #1728.
76 lines
2.7 KiB
C++
76 lines
2.7 KiB
C++
/*
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IPAddress.h - Base class that provides IPAddress
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Copyright (c) 2011 Adrian McEwen. All right reserved.
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef IPAddress_h
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#define IPAddress_h
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#include <stdint.h>
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#include <Printable.h>
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// A class to make it easier to handle and pass around IP addresses
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class IPAddress : public Printable {
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private:
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union {
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uint8_t bytes[4]; // IPv4 address
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uint32_t dword;
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} _address;
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// Access the raw byte array containing the address. Because this returns a pointer
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// to the internal structure rather than a copy of the address this function should only
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// be used when you know that the usage of the returned uint8_t* will be transient and not
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// stored.
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uint8_t* raw_address() { return _address.bytes; };
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public:
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// Constructors
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IPAddress();
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IPAddress(uint8_t first_octet, uint8_t second_octet, uint8_t third_octet, uint8_t fourth_octet);
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IPAddress(uint32_t address);
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IPAddress(const uint8_t *address);
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// Overloaded cast operator to allow IPAddress objects to be used where a pointer
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// to a four-byte uint8_t array is expected
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operator uint32_t() const { return _address.dword; };
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bool operator==(const IPAddress& addr) const { return _address.dword == addr._address.dword; };
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bool operator==(const uint8_t* addr) const;
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// Overloaded index operator to allow getting and setting individual octets of the address
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uint8_t operator[](int index) const { return _address.bytes[index]; };
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uint8_t& operator[](int index) { return _address.bytes[index]; };
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// Overloaded copy operators to allow initialisation of IPAddress objects from other types
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IPAddress& operator=(const uint8_t *address);
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IPAddress& operator=(uint32_t address);
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virtual size_t printTo(Print& p) const;
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friend class EthernetClass;
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friend class UDP;
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friend class Client;
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friend class Server;
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friend class DhcpClass;
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friend class DNSClient;
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};
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const IPAddress INADDR_NONE(0,0,0,0);
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#endif
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