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Topic: Getting remote IP from ASocket (Read 2401 times) previous topic - next topic


Oct 08, 2011, 12:30 am Last Edit: Oct 08, 2011, 12:36 am by freelancer Reason: 1
I very recently got my Ethernet-enabled Arduino and I'm trying to get into network programming. I decided to use the Ethernet library from http://code.google.com/p/kegger/ (http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1239258729/45) because it seems to have more features than the standard library, and I got it working more easily.
There's only one issue... Once I've opened a listening TCP socket with socket.initTCP(port) and socket.listenTCP(), and have a client connected, how do I get its IP? I've tried to find anything relevant in the code, but it doesn't seem to be there. This might be a really basic question, but I've never done any TCP/IP programming this low-level before.



Oct 08, 2011, 12:49 pm Last Edit: Oct 08, 2011, 01:15 pm by SurferTim Reason: 1
With either library, modification of the ethernet library runtime code is required. Neither have a user function to retrieve the client IP, even tho the register function to read it is already in the library code.

I could help you get that client IP from the Arduino ethernet library, but not the library you are using.

Edit: I had to test it. My test code works fine with the Arduino ethernet library.
How about this for a function call:
Code: [Select]
byte ipBuffer[4];



Did you write that function yourself? I can't find it in the original library code. But yeah, if you can show me how to get the IP with that library, I could probably adapt it to the one I'm using. Any help is appreciated.


Oct 08, 2011, 02:39 pm Last Edit: Oct 08, 2011, 04:27 pm by SurferTim Reason: 1
Did you write that function yourself?

Yes. It didn't take much with the Arduino library. I am very familiar with it now.

Here are the additions:
In /libraries/Ethernet/client.cpp, add this. I put it after the Client::available() function.
Code: [Select]
uint8_t Client::remoteIP(uint8_t *buf) {
 if (_sock != MAX_SOCK_NUM)
   return W5100.readSnDIPR(_sock,buf);
 return 0;

In /libraries/Ethernet/client.h, add this. I again put it after the declaration for available().
Code: [Select]
 virtual uint8_t remoteIP(uint8_t *buf);

Then use it like this after the client.connect() or client.connected():

Code: [Select]
byte ipBuffer[4];
char outBuffer[18];



Thank you! Changed it slightly to work with the ASocket class, and it works like a charm.

For reference:
Code: [Select]

bool ASocket::remoteIP(uint8_t *buf) {
if (_sock != MAX_SOCK_NUM) {
getSn_DIPR(_sock, buf);
return true;
return false;


You are welcome. Very good-looking function there! I can see the similarity of the two libraries now.


Jan 05, 2013, 01:57 am Last Edit: Jan 05, 2013, 01:59 am by nathanas Reason: 1
Dear surfer tim,
After having a new installation of windows on my PC, I tried to make tha library working again but with no luck.

The log is this one, and I am using Arduino 1.0.3.

Code: [Select]

homepage.ino: In function 'void homepage()':
homepage:30: error: no matching function for call to 'EthernetClient::remoteIP()'
C:\Program Files (x86)\arduino-1.0.3\libraries\Ethernet/EthernetClient.h:20: note: candidates are: virtual uint8_t EthernetClient::remoteIP(uint8_t*)
login.ino: In function 'void login()':
login:32: error: no matching function for call to 'EthernetClient::remoteIP()'
C:\Program Files (x86)\arduino-1.0.3\libraries\Ethernet/EthernetClient.h:20: note: candidates are: virtual uint8_t EthernetClient::remoteIP(uint8_t*)


Compiler errors without code are pretty useless. All we can suggest is that you fix the problem(s).


Jan 05, 2013, 02:14 am Last Edit: Jan 05, 2013, 02:16 am by nathanas Reason: 1
The code had been working before with no problem.
I just wanted to upload the same code and I can;t because of the library. I am pasting the code given above to the EthernetClient.cpp & ethernetclient.h files with no syntax errors. Then I save the the notepad file as .cpp/.h

Code: [Select]
#include <SPI.h>        
#include <Ethernet.h>
#include <EthernetUdp.h>

// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {  
 0x00, 0x00, 0xAA, 0xBB, 0xCC, 0xDD };
IPAddress ip(192, 168, 10, XXX);

unsigned int localPort = 8070;      // local port to listen on

// An EthernetUDP instance to let us send and receive packets over UDP

EthernetServer server(8070);
void setup() {
 // start the Ethernet and UDP:


void loop() {

EthernetClient client = server.available();
 Serial.println("Waiting for client... ");
if(client) {
 Serial.println("Client request!!!! ");
while (client.connected()) {
 while(client.available()) {
  char c = client.read();
   if (c == '\n' ) {
   Serial.print("Received packet ...    ");

   Serial.print("From IP : ");

IPAddress clientIP = client.remoteIP();
   //print out the remote connection's IP address


I think that when I managed to make the library work some time ago, I edited Ethernet.h/cpp & EthernetClient files. I am not sure. I had found a link from Surfer Tim and I don;t remember if its the same.


Code: [Select]
IPAddress clientIP = client.remoteIP();
The remoteIP() method does not return an IPAddress. It takes an argument of a pointer to an IPAddress where the value is to be stored.


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