sockets: from c to c++

[careca]

Hi, I'm having problem with compiling c code with g++. I'm doing this because I want to write a little program in C++ from an example in C.
In particular, the
inet_addr
function is not found when I compile with g++.
How can I resolve? Libraries should not be the same in C and C++ for sockets?

[heikaman]

use inet_aton instead of inet_addr it's better, man inet_aton.

and can you post the complete example ?

[careca]

This is my main.cpp


#include <iostream>
#include <string>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <fstream>

//#include <arpa/inet.h>
//#include <stdio.h>
using namespace std;

int main(int argc, char** argv)
{
// Local variables
int aPortIn = 5000;
int aPortOut = 5001;
int sockfd;
struct sockaddr_in aLocal;
struct sockaddr_in *aRemotes;
string aPathFile = "/home/Andrés/Desktop/ConfFile";
string aPathTextFile = "/home/Andrés/Desktop/TextFile";
string aBuffer = "";
string aIPtemp;
string *aIPs;
int aN;
int aNtemp;
int aIndex;

// Check argument is IP
if (argc != 2)
{

fprintf(stderr, "Usage: Local %s IP address\n", argv[0]);
exit(1);
}

// Create socket
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
perror(NULL);
exit(2);
}

aLocal.sin_family = AF_INET;
aLocal.sin_addr.s_addr = inet_addr(argv[1]);
aLocal.sin_port = htons(aPortOut);

// Binding
int e = bind( sockfd, (struct sockaddr *)&aLocal, sizeof(aLocal));
cout << argv[1]<<" !\n"<< e <<" \n";
if(bind( sockfd, (struct sockaddr *)&aLocal, sizeof(aLocal) ) < 0)
{
perror(NULL);
close(sockfd);cout << argv[1]<<"!\n";
exit(3);
}

// Load nodes
ifstream aFile;
aFile.open(aPathFile.c_str(), ios::in);
if(!aFile) { cout << "The CONF FILE is missing!\n"; exit(3); }

aFile >> aN;
aIPs = new string[aN];
aRemotes = new sockaddr_in[aN];

aIndex = 0;
while( !aFile.eof() && aIndex < aN )
{
aFile >> aIPs[aIndex];
cout << aIPs[aIndex] << "\n";
aRemotes[aIndex].sin_family = AF_INET;
aRemotes[aIndex].sin_addr.s_addr = inet_addr(aIPs[aIndex].c_str());
aRemotes[aIndex].sin_port = htons(aPortIn);
aIndex++;
}

aFile.close();

// Load File
fstream aTextFile;
aTextFile.open(aPathTextFile.c_str(), ios::in|ios::out);
if(!aTextFile) { cout << "The TEXT FILE is missing!\n"; exit(3); }
while( !aTextFile.eof() )
{
//aTextFile >> aTemp;
//aBuffer.append(aTemp);
}

// Creating connection
if( listen(sockfd, aN) < 0)
{
perror(NULL);
close(sockfd);
exit(3);
}


/* Initialization: How to
* Fork n times
* Create link, send ok
* Children die
* Parent recreate link to go on
*/

/* How link will be:
* Server-Client for every node
* One port for outgoing calls
* one for incoming
* Nodes will be identified by id in the messages
*/

// CreateInitialLink() <-
// Define: address of *NumberOfNodes, *NumberOfNodesUpToNow
// *sockaddr_in



aTextFile.close();
close(sockfd);

return 0;
}


I'm working on it. I solved this problem by including
<arpa/inet.h>
but, i don't want to include it, because I want to do like my professor does.

[heikaman]

I'm working on it. I solved this problem by including
<arpa/inet.h>
but, i don't want to include it, because I want to do like my professor does.


inet_addr and inet_aton are both defined in <arpa/inet.h> so you have to include it, maybe your professor forgot to include it :)

and inet_aton is better, because inet_addr returns -1 on error which is a valid address "255.255.255.255".
read man inet_aton.

[careca]

Here is my professors
datagram_sender.c
He compiles it with gcc, and works (I mean, there is no arpa library, and it inet_addr() and bind() correctly)

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>

#define SIZE 1400
char buf[SIZE];

#define RECV_PORT 5000
#define SENDER_PORT 5001

int main(int argc, char *argv[]) {

int sockfd; int nread;
struct sockaddr_in remote_addr, local_addr;
int len;

if (argc != 2) {
fprintf(stderr, "Usage: %s IPaddr\n", argv[0]);
exit(1);
}

if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
perror(NULL);
exit(2);
}

local_addr.sin_family = AF_INET;
local_addr.sin_addr.s_addr = htonl(INADDR_ANY);
local_addr.sin_port = htons(SENDER_PORT);

remote_addr.sin_family = AF_INET;
remote_addr.sin_addr.s_addr = inet_addr(argv[1]);
remote_addr.sin_port = htons(RECV_PORT);

if (bind(sockfd, (struct sockaddr *)&local_addr, sizeof(local_addr)) < 0) {
perror(NULL);
close(sockfd);
exit(3);
}

len = sizeof(remote_addr);
sendto(sockfd, "Hi", 2, 0, (struct sockaddr *)&remote_addr, len);
printf (" I sent a message...\n");
nread = recvfrom(sockfd, buf, SIZE, 0, (struct sockaddr *)&local_addr, &len);
printf (" I got back %s\n", buf);
close(sockfd);
exit(0);
}