Type invalid conversion from ‘int*’ to ‘socklen_t*

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Hi there, i saw the other thread about this error here and since his correctiong didnt fix mine i thought i'd be ok to create a new one about it.
Im quite new to C/C++ Coding so i hope you'll be kind and explain things in details.


my errors:
1. :initializing argument 6 of ‘ssize_t recvfrom(int, void*, size_t, int, sockaddr*, socklen_t*)’ receiver.cpp mlt_r line 70 C/C++ Problem
2. :invalid conversion from ‘int*’ to ‘socklen_t*’ receiver.cpp mlt_r line 70 C/C++ Problem
[B"]3." :[/B] make: *** [receiver.o] Error 1 mlt_r line 0 C/C++ Problem


Here is my code:

Code:
#include <limits.h>
#include <netdb.h>
#include <iostream>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <signal.h>
#include <unistd.h>
#include <sys/un.h>
#include <arpa/inet.h>



#define HELLO_PORT 51075
#define HELLO_GROUP "localhost"
#define MSGBUFSIZE 256
typedef int socklen_t; //added to try after reading the other thread on this forum

main(int argc, char *argv[])
{
     struct sockaddr_in addr;
     int fd, nbytes,addrlen;
     struct ip_mreq mreq;
     char msgbuf[MSGBUFSIZE];

     /* create what looks like an ordinary UDP socket */
     if ((fd=socket(AF_INET,SOCK_DGRAM,0)) < 0) {
	  perror("socket");
	  exit(1);
     }

     /* set up destination address */
     memset(&addr,0,sizeof(addr));
     addr.sin_family=AF_INET;
     addr.sin_addr.s_addr=htonl(INADDR_ANY); /* N.B.: differs from sender */
     addr.sin_port=htons(HELLO_PORT);

     /* bind to receive address */
     if (bind(fd,(struct sockaddr *) &addr,sizeof(addr)) < 0) {
	  perror("bind");
	  exit(1);
     }

     /* use setsockopt() to request that the kernel join a multicast group */
     mreq.imr_multiaddr.s_addr=inet_addr(HELLO_GROUP);
     mreq.imr_interface.s_addr=htonl(INADDR_ANY);
     if (setsockopt(fd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq)) < 0) {
	  perror("setsockopt");
	  exit(1);
     }

     /* now just enter a read-print loop */
     while (1) {
	  addrlen=sizeof(addr);
	  if ((nbytes=recvfrom(fd,msgbuf,MSGBUFSIZE,0,
			       (struct sockaddr *) &addr, &addrlen)) < 0) {
	       perror("recvfrom");
	       exit(1);
	  }
	  printf("Received: %s nbytes: %d \n",msgbuf, nbytes);
     }
}
 
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AMetnik said:
Hi there, i saw the other thread about this error here and since his correctiong didnt fix mine i thought i'd be ok to create a new one about it.
Im quite new to C/C++ Coding so i hope you'll be kind and explain things in details.


my errors:
1. :initializing argument 6 of ‘ssize_t recvfrom(int, void*, size_t, int, sockaddr*, socklen_t*)’ receiver.cpp mlt_r line 70 C/C++ Problem
2. :invalid conversion from ‘int*’ to ‘socklen_t*’ receiver.cpp mlt_r line 70 C/C++ Problem
[B"]3." :[/B] make: *** [receiver.o] Error 1 mlt_r line 0 C/C++ Problem


Here is my code:

Code:
#include <limits.h>
#include <netdb.h>
#include <iostream>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <signal.h>
#include <unistd.h>
#include <sys/un.h>
#include <arpa/inet.h>



#define HELLO_PORT 51075
#define HELLO_GROUP "localhost"
#define MSGBUFSIZE 256
typedef int socklen_t; //added to try after reading the other thread on this forum

main(int argc, char *argv[])
{
     struct sockaddr_in addr;
     int fd, nbytes,addrlen;
     struct ip_mreq mreq;
     char msgbuf[MSGBUFSIZE];

     /* create what looks like an ordinary UDP socket */
     if ((fd=socket(AF_INET,SOCK_DGRAM,0)) < 0) {
	  perror("socket");
	  exit(1);
     }

     /* set up destination address */
     memset(&addr,0,sizeof(addr));
     addr.sin_family=AF_INET;
     addr.sin_addr.s_addr=htonl(INADDR_ANY); /* N.B.: differs from sender */
     addr.sin_port=htons(HELLO_PORT);

     /* bind to receive address */
     if (bind(fd,(struct sockaddr *) &addr,sizeof(addr)) < 0) {
	  perror("bind");
	  exit(1);
     }

     /* use setsockopt() to request that the kernel join a multicast group */
     mreq.imr_multiaddr.s_addr=inet_addr(HELLO_GROUP);
     mreq.imr_interface.s_addr=htonl(INADDR_ANY);
     if (setsockopt(fd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq)) < 0) {
	  perror("setsockopt");
	  exit(1);
     }

     /* now just enter a read-print loop */
     while (1) {
	  addrlen=sizeof(addr);
	  if ((nbytes=recvfrom(fd,msgbuf,MSGBUFSIZE,0,
			       (struct sockaddr *) &addr, &addrlen)) < 0) {
	       perror("recvfrom");
	       exit(1);
	  }
	  printf("Received: %s nbytes: %d \n",msgbuf, nbytes);
     }
}


I don't really know specifically what the problem is in this case, but I can recommend a few things to check that might help find it.

For all these tests - remove the "typedef int socklen_t;"...

- can you check what happens if you define "addrlen" to actually be a "socklen_t"? Does that fix the error? if it doesn't... then I really don't know :)

- if that does solve the problem - what happens if you define "addrlen" to be of type "long"?

- what happens if you add "(socklen_t*)" just before the "&addrlen" argument? Is the error still the same?

Let me know how these things work out :)
 

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