server client problem

hi all,

i started learning socket's
tried to write a simple client server under unix
and got a runtime error

i run the server and client on to shells (internal network \ localhost \ whatever)
after sending the message the client (sending) throws this: Illegal instruction (core dumped)
and the server receiving throws: Segmentation fault (core dumped)

the server code

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>



int main ()
{
  int socketfd , incomfd, err;
  struct sockaddr_in myip;
  struct sockaddr_in hisip;
  int sin_size;
  int bytes_recv, len=20, backlog=5;
  char buff[40];
  int myport=55555;

socketfd = socket(PF_INET , SOCK_STREAM , 0);

if(socketfd==-1)
{printf("unable to creat socket!!");
 exit(1);
}

 
// intilaize myip address structer
 
myip.sin_family = AF_INET;
myip.sin_port = htons(myport);
myip.sin_addr.s_addr =INADDR_ANY; //inet_addr("127.0.0.1"); // this ip address is for the loopback network (internal ip address).
memset(myip.sin_zero, '\0', sizeof (myip.sin_zero));


err=bind ( socketfd , (struct sockaddr *) &myip , sizeof(myip));

if(err==-1)
{printf("unable to use port... bind()");
 exit(1);
}   


err=listen(socketfd , backlog);

if(err==-1)
{printf("error listening");
 exit(1);
}

sin_size = sizeof (hisip);
incomfd= accept(socketfd , (struct sockaddr *) &hisip , &sin_size);

if(incomfd==-1)
{printf("error accepting!");
 exit(1);
}

bytes_recv=recv(incomfd , buff , len , 0);

printf("bytes recived: %d",bytes_recv);

if(bytes_recv==-1)
{printf("error while recieving");
 exit(1);
}

close(socketfd);

printf("The message recieved: %s \n", *buff);

return 0;
}

---

the client code:

Code:

---

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>


#include <netinet/in.h>
#include <arpa/inet.h>



int main ()
{
  int socketfd;
  struct sockaddr_in destip;
  int destport = 55555;
  int err ,sent_bytes, len;
  char *msg;

socketfd = socket( PF_INET , SOCK_STREAM , 0);

if(socketfd==-1)
{printf("couldn't creat socket!!");
 exit(1);
}


destip.sin_family = AF_INET;
destip.sin_port = htons(destport);
destip.sin_addr.s_addr =INADDR_ANY; //inet_addr("127.0.0.1");
memset(destip.sin_zero, '\0', sizeof (destip.sin_zero));

err=connect( socketfd , (struct sockaddr *) &destip , sizeof(destip));

if (err==-1)
{printf("couldn't connect!");
 exit(1);
}

printf("Enter the message to send: \n");
gets(msg);

len=strlen(msg);
printf("The message is %s \n and it is %d charecters long \n",msg , len);
sent_bytes= send( socketfd , msg , len , 0);
printf("bytes sent %d\n", sent_bytes);
close(socketfd);

return 0;
}

---

i really cant figure what am i doing wrong
please direct me to the write direction

thanx ;)

Some remarks (not related to your problem):

Code:

---

myip.sin_addr.s_addr =INADDR_ANY; //inet_addr("127.0.0.1"); // this ip address is for the loopback network (internal ip address).

---

The comment is wrong, INADDR_ANY indicates to accept data from any (network) interface,
which is very different of only the loopback interface.

You also forget to convert the local encoding to the network encoding:

Code:

---

...s_addr=htonl(INADDR_ANY);

---

or

Code:

---

...s_addr=htonl(0x7F000001); // localhost only.

---

you did it correctly for the port (htons(port)).

Things to fix (responsible for the SEGV):

server-side:

Code:

---

  char buff[40];
  ...
  printf("The message recieved: %s \n", *buff);

---

client-side:

Code:

---

  char *msg;
  ...
  gets(msg);

---

Besides my compiler is nice enough to say:
"warning: the `gets' function is dangerous and should not be used."

thank you for your help

root4:
my comment is on the command inet_addr("127.0.0.1");
if this is the case is it still wrong to say its an internal ip address?

and the reason i didnt convert the INADDR_ANY is because i understood it is actually a zero value but i will add it

also i add the fix as you said and it works!!
i thought my problem is in the send\recv
lol i allways miss the simple things... (shame on me) 8^/

thank you :)

Quote:

---

the reason i didnt convert the INADDR_ANY is because i understood it is actually a zero value

---

It is indeed zero, but -despite I was not able to find a concrete reference about that- I think the value of this symbol is implementation-defined as the actual definition of s_addr may vary.
Omitting the encoding conversion on INADDR_ANY (which may be something else than 0) may lead to unexpected errors/behavior. However if you're sure your implementation uses integer as addresses field, the conversion is indeed useless. Someone else may be able to provide pointers on the subject.

Quote:

---

my comment is on the command inet_addr("127.0.0.1");

---

Ok, please ignore my remark on this line.

Couple of other notes:

Code:

---

printf("The message recieved: %s \n", *buff);

---

Your format string indicates a string (%s), but you pass a character (*buff). Probably don't want the * there.
Additionally, you have no guarantee that buff is a string - you should null terminate the data you just recv'd to be sure that it's null terminated. A simple:

Code:

---

buff[bytes_recv] = '\0';

---

...will append a null terminator. Do this before passing it to printf(). Be sure buff is at least bytes_recv + 1 in size (it is in your code, as long as you pass 39 or less to recv().)