Remote IP on EthernetClient

[DarioDaF]

I sudgest adding a function to read the IP of the Clients

Changes needed:

EthernetClient.h

class EthernetClient : public Client {

public:

  virtual uint8_t remoteIP(uint8_t *buf); // Change

};

EthernetClient.cpp

uint8_t EthernetClient::remoteIP(uint8_t *buf) {
  if (_sock != MAX_SOCK_NUM)
    return W5100.readSnDIPR(_sock, buf);
  return 0;
}

It is a simple and usefull change in the library that can be used to retrive the IP address of a client connected to the EthernetServer.

[PaulStoffregen]

If this is added, it probably ought to use the IPAddress class from the core library rather than an array of bytes. Long-term, the C++ class can be much more easily extended to support IPv6.

[q2dg]

Well...maybe it's worthy read this: #1700

On the other hand, a week ago I suggested more some love to this and others improvements on Ethernet library...: arduino-libraries/Ethernet#36 (comment)

[per1234]

Well...maybe it's worthy read this: #1700

Yes, this was discussed in 2013 and rejected but maybe worth revisiting? Note that implementation uses IPAddress: ca37de4
I've been using that function for a couple years and I think it would be nice for consistency with EthernetUDP which already has remoteIP().

Here's the associated discussion on the Developers mailing list: https://groups.google.com/a/arduino.cc/forum/#!searchin/developers/remoteIP/developers/LW2xYj3LPM0/orkaW_SiNpAJ. The link to it on that PR has gone dead.

[per1234]

Fixed by arduino-libraries/Ethernet@ac84329