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Commit52b367a

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Rewrite IPAddress without union
Using a union allowed undefined behavior for 8-bit integer INPUT and OUTPUT arguments through a 32-bit integer (and vice versa).Write throught union::uint8_t[16] and read thoutght union::uint32_t[4]is a undefined behavior.C++ standard says (https://timsong-cpp.github.io/cppwp/n4659/class.union#1):"At most one of the non-static data members of an object of union typecan be active at any time, that is, the value of at most one of thenon-static data members can be stored in a union at any time. [ Note:One special guarantee is made in order to simplify the use of unions:If a standard-layout union contains several standard-layout structsthat share a common initial sequence, and if a non-static data memberof an object of this standard-layout union type is active and is oneof the standard-layout structs, it is permitted to inspect the commoninitial sequence of any of the standard-layout struct members; see[class.mem].  — end note ]"and (https://timsong-cpp.github.io/cppwp/n4659/class.mem#22):"Two standard-layout unions are layout-compatible if they have the same number of non-static data members and corresponding non-static data members (in any order) have layout-compatible types."you can't hope that compilers don't seem to do undefined behavior at the momentAlso createdespressif/arduino-esp32#8829 PR dependent on changing the current API.
1 parentfc9a636 commit52b367a

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2 files changed

+56
-82
lines changed

2 files changed

+56
-82
lines changed

‎api/IPAddress.cpp‎

Lines changed: 50 additions & 73 deletions
Original file line numberDiff line numberDiff line change
@@ -19,53 +19,30 @@
1919

2020
#include"IPAddress.h"
2121
#include"Print.h"
22+
#include<algorithm>
23+
#include<cstdint>
2224

2325
usingnamespacearduino;
2426

25-
IPAddress::IPAddress(): IPAddress(IPv4) {}
27+
IPAddress::IPAddress()= default;
2628

27-
IPAddress::IPAddress(IPType ip_type)
28-
{
29-
_type = ip_type;
30-
memset(_address.bytes,0,sizeof(_address.bytes));
31-
}
29+
IPAddress::IPAddress(IPType ip_type) : _type(ip_type) {}
3230

3331
IPAddress::IPAddress(uint8_t first_octet,uint8_t second_octet,uint8_t third_octet,uint8_t fourth_octet)
3432
{
35-
_type = IPv4;
36-
memset(_address.bytes,0,sizeof(_address.bytes));
37-
_address.bytes[IPADDRESS_V4_BYTES_INDEX] = first_octet;
38-
_address.bytes[IPADDRESS_V4_BYTES_INDEX +1] = second_octet;
39-
_address.bytes[IPADDRESS_V4_BYTES_INDEX +2] = third_octet;
40-
_address.bytes[IPADDRESS_V4_BYTES_INDEX +3] = fourth_octet;
33+
_address[IPADDRESS_V4_BYTES_INDEX] = first_octet;
34+
_address[IPADDRESS_V4_BYTES_INDEX +1] = second_octet;
35+
_address[IPADDRESS_V4_BYTES_INDEX +2] = third_octet;
36+
_address[IPADDRESS_V4_BYTES_INDEX +3] = fourth_octet;
4137
}
4238

43-
IPAddress::IPAddress(uint8_t o1,uint8_t o2,uint8_t o3,uint8_t o4,uint8_t o5,uint8_t o6,uint8_t o7,uint8_t o8,uint8_t o9,uint8_t o10,uint8_t o11,uint8_t o12,uint8_t o13,uint8_t o14,uint8_t o15,uint8_t o16) {
44-
_type = IPv6;
45-
_address.bytes[0] = o1;
46-
_address.bytes[1] = o2;
47-
_address.bytes[2] = o3;
48-
_address.bytes[3] = o4;
49-
_address.bytes[4] = o5;
50-
_address.bytes[5] = o6;
51-
_address.bytes[6] = o7;
52-
_address.bytes[7] = o8;
53-
_address.bytes[8] = o9;
54-
_address.bytes[9] = o10;
55-
_address.bytes[10] = o11;
56-
_address.bytes[11] = o12;
57-
_address.bytes[12] = o13;
58-
_address.bytes[13] = o14;
59-
_address.bytes[14] = o15;
60-
_address.bytes[15] = o16;
61-
}
39+
IPAddress::IPAddress(uint8_t o1,uint8_t o2,uint8_t o3,uint8_t o4,uint8_t o5,uint8_t o6,uint8_t o7,uint8_t o8,uint8_t o9,uint8_t o10,uint8_t o11,uint8_t o12,uint8_t o13,uint8_t o14,uint8_t o15,uint8_t o16) : _address{o1, o2, o3, o4, o5, o6, o7, o8, o9, o10, o11, o12, o13, o14, o15, o16}, _type(IPv6) {}
6240

63-
IPAddress::IPAddress(uint32_t address)
41+
// IPv4 only
42+
IPAddress::IPAddress(uint32_t address)
6443
{
65-
// IPv4 only
66-
_type = IPv4;
67-
memset(_address.bytes,0,sizeof(_address.bytes));
68-
_address.dword[IPADDRESS_V4_DWORD_INDEX] = address;
44+
uint32_t& addressRef =reinterpret_cast<uint32_t&>(_address[IPADDRESS_V4_BYTES_INDEX]);
45+
addressRef = address;
6946

7047
// NOTE on conversion/comparison and uint32_t:
7148
// These conversions are host platform dependent.
@@ -78,14 +55,12 @@ IPAddress::IPAddress(uint32_t address)
7855

7956
IPAddress::IPAddress(constuint8_t *address) : IPAddress(IPv4, address) {}
8057

81-
IPAddress::IPAddress(IPType ip_type,constuint8_t *address)
58+
IPAddress::IPAddress(IPType ip_type,constuint8_t *address) : _type(ip_type)
8259
{
83-
_type = ip_type;
8460
if (ip_type == IPv4) {
85-
memset(_address.bytes,0,sizeof(_address.bytes));
86-
memcpy(&_address.bytes[IPADDRESS_V4_BYTES_INDEX], address,sizeof(uint32_t));
61+
std::copy(address, address +4, &_address[IPADDRESS_V4_BYTES_INDEX]);
8762
}else {
88-
memcpy(_address.bytes, address,sizeof(_address.bytes));
63+
std::copy(address, address + _address.size(),_address.begin());
8964
}
9065
}
9166

@@ -97,18 +72,18 @@ IPAddress::IPAddress(const char *address)
9772
StringIPAddress::toString4()const
9873
{
9974
char szRet[16];
100-
snprintf(szRet,sizeof(szRet),"%u.%u.%u.%u", _address.bytes[IPADDRESS_V4_BYTES_INDEX], _address.bytes[IPADDRESS_V4_BYTES_INDEX +1], _address.bytes[IPADDRESS_V4_BYTES_INDEX +2], _address.bytes[IPADDRESS_V4_BYTES_INDEX +3]);
75+
snprintf(szRet,sizeof(szRet),"%u.%u.%u.%u", _address[IPADDRESS_V4_BYTES_INDEX], _address[IPADDRESS_V4_BYTES_INDEX +1], _address[IPADDRESS_V4_BYTES_INDEX +2], _address[IPADDRESS_V4_BYTES_INDEX +3]);
10176
returnString(szRet);
10277
}
10378

10479
StringIPAddress::toString6()const
10580
{
10681
char szRet[40];
10782
snprintf(szRet,sizeof(szRet),"%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x",
108-
_address.bytes[0], _address.bytes[1], _address.bytes[2], _address.bytes[3],
109-
_address.bytes[4], _address.bytes[5], _address.bytes[6], _address.bytes[7],
110-
_address.bytes[8], _address.bytes[9], _address.bytes[10], _address.bytes[11],
111-
_address.bytes[12], _address.bytes[13], _address.bytes[14], _address.bytes[15]);
83+
_address[0], _address[1], _address[2], _address[3],
84+
_address[4], _address[5], _address[6], _address[7],
85+
_address[8], _address[9], _address[10], _address[11],
86+
_address[12], _address[13], _address[14], _address[15]);
11287
returnString(szRet);
11388
}
11489

@@ -135,7 +110,7 @@ bool IPAddress::fromString4(const char *address)
135110
int16_t acc = -1;// Accumulator
136111
uint8_t dots =0;
137112

138-
memset(_address.bytes,0,sizeof(_address.bytes));
113+
_address.fill(0);
139114
while (*address)
140115
{
141116
char c = *address++;
@@ -157,7 +132,7 @@ bool IPAddress::fromString4(const char *address)
157132
/* No value between dots, e.g. '1..'*/
158133
returnfalse;
159134
}
160-
_address.bytes[IPADDRESS_V4_BYTES_INDEX + dots++] = acc;
135+
_address[IPADDRESS_V4_BYTES_INDEX + dots++] = acc;
161136
acc = -1;
162137
}
163138
else
@@ -175,7 +150,7 @@ bool IPAddress::fromString4(const char *address)
175150
/* No value between dots, e.g. '1..'*/
176151
returnfalse;
177152
}
178-
_address.bytes[IPADDRESS_V4_BYTES_INDEX +3] = acc;
153+
_address[IPADDRESS_V4_BYTES_INDEX +3] = acc;
179154
_type = IPv4;
180155
returntrue;
181156
}
@@ -215,8 +190,8 @@ bool IPAddress::fromString6(const char *address) {
215190
if (colons ==7)
216191
// too many separators
217192
returnfalse;
218-
_address.bytes[colons *2] = acc >>8;
219-
_address.bytes[colons *2 +1] = acc &0xff;
193+
_address[colons *2] = acc >>8;
194+
_address[colons *2 +1] = acc &0xff;
220195
colons++;
221196
acc =0;
222197
}
@@ -233,15 +208,15 @@ bool IPAddress::fromString6(const char *address) {
233208
// Too many segments (double colon must be at least one zero field)
234209
returnfalse;
235210
}
236-
_address.bytes[colons *2] = acc >>8;
237-
_address.bytes[colons *2 +1] = acc &0xff;
211+
_address[colons *2] = acc >>8;
212+
_address[colons *2 +1] = acc &0xff;
238213
colons++;
239214

240215
if (double_colons != -1) {
241216
for (int i = colons *2 - double_colons *2 -1; i >=0; i--)
242-
_address.bytes[16 - colons *2 + double_colons *2 + i] = _address.bytes[double_colons *2 + i];
217+
_address[16 - colons *2 + double_colons *2 + i] = _address[double_colons *2 + i];
243218
for (int i = double_colons *2; i <16 - colons *2 + double_colons *2; i++)
244-
_address.bytes[i] =0;
219+
_address[i] =0;
245220
}
246221

247222
_type = IPv6;
@@ -252,8 +227,10 @@ IPAddress& IPAddress::operator=(const uint8_t *address)
252227
{
253228
// IPv4 only conversion from byte pointer
254229
_type = IPv4;
255-
memset(_address.bytes,0,sizeof(_address.bytes));
256-
memcpy(&_address.bytes[IPADDRESS_V4_BYTES_INDEX], address,sizeof(uint32_t));
230+
231+
_address.fill(0);
232+
std::copy(address, address +4, &_address[IPADDRESS_V4_BYTES_INDEX]);
233+
257234
return *this;
258235
}
259236

@@ -268,35 +245,35 @@ IPAddress& IPAddress::operator=(uint32_t address)
268245
// IPv4 conversion
269246
// See note on conversion/comparison and uint32_t
270247
_type = IPv4;
271-
memset(_address.bytes,0,sizeof(_address.bytes));
272-
_address.dword[IPADDRESS_V4_DWORD_INDEX] = address;
248+
_address.fill(0);
249+
uint32_t& addressRef =reinterpret_cast<uint32_t&>(_address[IPADDRESS_V4_BYTES_INDEX]);
250+
addressRef = address;
273251
return *this;
274252
}
275253

276254
bool IPAddress::operator==(const IPAddress& addr)const {
277-
return (addr._type == _type)
278-
&& (memcmp(addr._address.bytes, _address.bytes,sizeof(_address.bytes)) ==0);
255+
return addr._type == _type &&std::equal(addr._address.begin(), addr._address.end(), _address.begin());
279256
}
280257

281258
bool IPAddress::operator==(constuint8_t* addr)const
282259
{
283260
// IPv4 only comparison to byte pointer
284261
// Can't support IPv6 as we know our type, but not the length of the pointer
285-
return _type == IPv4 &&memcmp(addr, &_address.bytes[IPADDRESS_V4_BYTES_INDEX],sizeof(uint32_t)) ==0;
262+
return _type == IPv4 &&std::equal(_address.begin(), _address.end(), addr);
286263
}
287264

288265
uint8_t IPAddress::operator[](int index)const {
289266
if (_type == IPv4) {
290-
return _address.bytes[IPADDRESS_V4_BYTES_INDEX + index];
267+
return _address[IPADDRESS_V4_BYTES_INDEX + index];
291268
}
292-
return _address.bytes[index];
269+
return _address[index];
293270
}
294271

295272
uint8_t& IPAddress::operator[](int index) {
296273
if (_type == IPv4) {
297-
return _address.bytes[IPADDRESS_V4_BYTES_INDEX + index];
274+
return _address[IPADDRESS_V4_BYTES_INDEX + index];
298275
}
299-
return _address.bytes[index];
276+
return _address[index];
300277
}
301278

302279
size_tIPAddress::printTo(Print& p)const
@@ -310,7 +287,7 @@ size_t IPAddress::printTo(Print& p) const
310287
int8_t current_start = -1;
311288
int8_t current_length =0;
312289
for (int8_t f =0; f <8; f++) {
313-
if (_address.bytes[f *2] ==0 && _address.bytes[f *2 +1] ==0) {
290+
if (_address[f *2] ==0 && _address[f *2 +1] ==0) {
314291
if (current_start == -1) {
315292
current_start = f;
316293
current_length =1;
@@ -327,10 +304,10 @@ size_t IPAddress::printTo(Print& p) const
327304
}
328305
for (int f =0; f <8; f++) {
329306
if (f < longest_start || f >= longest_start + longest_length) {
330-
uint8_t c1 = _address.bytes[f *2] >>4;
331-
uint8_t c2 = _address.bytes[f *2] &0xf;
332-
uint8_t c3 = _address.bytes[f *2 +1] >>4;
333-
uint8_t c4 = _address.bytes[f *2 +1] &0xf;
307+
uint8_t c1 = _address[f *2] >>4;
308+
uint8_t c2 = _address[f *2] &0xf;
309+
uint8_t c3 = _address[f *2 +1] >>4;
310+
uint8_t c4 = _address[f *2 +1] &0xf;
334311
if (c1 >0) {
335312
n += p.print((char)(c1 <10 ?'0' + c1 :'a' + c1 -10));
336313
}
@@ -357,10 +334,10 @@ size_t IPAddress::printTo(Print& p) const
357334
// IPv4
358335
for (int i =0; i <3; i++)
359336
{
360-
n += p.print(_address.bytes[IPADDRESS_V4_BYTES_INDEX + i], DEC);
337+
n += p.print(_address[IPADDRESS_V4_BYTES_INDEX + i], DEC);
361338
n += p.print('.');
362339
}
363-
n += p.print(_address.bytes[IPADDRESS_V4_BYTES_INDEX +3], DEC);
340+
n += p.print(_address[IPADDRESS_V4_BYTES_INDEX +3], DEC);
364341
return n;
365342
}
366343

‎api/IPAddress.h‎

Lines changed: 6 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -19,12 +19,12 @@
1919

2020
#pragma once
2121

22+
#include<array>
2223
#include<stdint.h>
2324
#include"Printable.h"
2425
#include"String.h"
2526

2627
#defineIPADDRESS_V4_BYTES_INDEX12
27-
#defineIPADDRESS_V4_DWORD_INDEX3
2828

2929
// forward declarations of global name space friend classes
3030
classEthernetClass;
@@ -42,17 +42,14 @@ enum IPType {
4242

4343
classIPAddress :publicPrintable {
4444
private:
45-
union {
46-
uint8_t bytes[16];
47-
uint32_t dword[4];
48-
} _address;
49-
IPType _type;
45+
alignas(alignof(uint32_t)) std::array<uint8_t,16> _address{};
46+
IPType _type{IPv4};
5047

5148
// Access the raw byte array containing the address. Because this returns a pointer
5249
// to the internal structure rather than a copy of the address this function should only
5350
// be used when you know that the usage of the returned uint8_t* will be transient and not
5451
// stored.
55-
uint8_t*raw_address() {return _type == IPv4 ? &_address.bytes[IPADDRESS_V4_BYTES_INDEX] : _address.bytes; }
52+
uint8_t*raw_address() {return _type == IPv4 ? &_address[IPADDRESS_V4_BYTES_INDEX] : _address.data(); }
5653

5754
public:
5855
// Constructors
@@ -75,7 +72,7 @@ class IPAddress : public Printable {
7572

7673
// Overloaded cast operator to allow IPAddress objects to be used where a uint32_t is expected
7774
// NOTE: IPv4 only; see implementation note
78-
operatoruint32_t()const {return _type == IPv4 ? _address.dword[IPADDRESS_V4_DWORD_INDEX] :0; };
75+
operatoruint32_t()const {return _type == IPv4 ?*reinterpret_cast<constuint32_t*>(&_address[IPADDRESS_V4_BYTES_INDEX]) :0; };
7976

8077
booloperator==(const IPAddress& addr)const;
8178
booloperator!=(const IPAddress& addr)const {return !(*this == addr); };
@@ -119,4 +116,4 @@ extern const IPAddress IN6ADDR_ANY;
119116
externconst IPAddress INADDR_NONE;
120117
}
121118

122-
using arduino::IPAddress;
119+
using arduino::IPAddress;

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