Not letting sockaddr(s) go out of scope

[robdapeepschamp]

I'm working on a program using static libraries & sockets with a server, and I thought I had it implemented correctly. I went to have it reviewed, since it isn't due for a week. The instructor said my sockaddr's could go out of scope and that I needed "some type of storage that maps file descriptor to the sockaddr pointer". He put a comment by the two lines in 'mysock.c' where it apparently will go out of scope. He mentioned something about creating a static struct to hold the separate data???

Can someone point me in the right direction/show me what he means? here are my .h/.c files.

mysock.h

#ifndef MYSOCK_H
#define MYSOCK_H

int tcp_init_server( const int port );
int tcp_server_accept( const int sd );
int tcp_client( const int server_port, const char * host, int * sd );

int fdprintf( const int fd, char * fmt, ... );
int fdgets(char *s, int size, const int fd );
int fdclose( const int fd );

#endif

mysock.c

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
/* for protobyname */
#include <netdb.h>
/* for socket, bind */
#include <sys/types.h>
#include <sys/socket.h>
/* fd io */
#include <unistd.h>
#include <stdarg.h>

int tcp_init_server(const int port)
{
    int proto_num = getprotobyname ( "tcp" )->p_proto;
    int sd;
    int rc;
    struct sockaddr_in serv; /* this goes out of scope */

    sd = socket( PF_INET, SOCK_STREAM, proto_num );
    if ( sd < 0 )
    {
        exit(1);
    }


    /*
     * setup the sockaddr_in
     */
    serv.sin_family = PF_INET;
    serv.sin_addr.s_addr = htonl ( INADDR_ANY );
    serv.sin_port = htons ( port );

    rc = bind( sd, (struct sockaddr *)&serv, sizeof(serv) );
    if ( rc < 0 )
    {
        exit(1);
    }

    rc = listen( sd, 10 );

    return sd;
}

int tcp_server_accept(const int sd)
{
    int sd2;
    struct sockaddr_in cli; /* this goes out of scope */
    socklen_t cli_len = sizeof(cli);

    sd2 = accept( sd, (struct sockaddr *)&cli, &cli_len );
    if ( sd2 <= 0 )
    {
        exit(1);
    }

    return sd2;
}

/*
 * input: a file descriptor along with printf style format string
 *          and arguements to match
 * output: processes the format string and arguments then writes the 
 *          data to the input file descriptor
 * return: the number of bytes written
 *
 * notes: hopefully getting identical behavior to do printf
 */
int fdprintf( const int fd, char * fmt, ... )
{
    char * buf = NULL;
    int bytes;
    va_list ap;

    va_start( ap, fmt );

    /* get the number of bytes needed */
    bytes = vsnprintf ( NULL, 0, fmt, ap );
    /* its actually one short */
    ++bytes;
    buf = ( char * ) malloc( sizeof(char) * ( bytes + 1 ) );
    bytes = vsnprintf ( buf, bytes, fmt, ap );

    /* write the data */
    write ( fd, buf, bytes );

    /* free the data and the va_list */
    va_end( ap );
    free ( buf );

    return bytes;
}

int fdgets(char *s, int size, const int fd )
{
	int r = read(fd, s, size);
	s[r] = 0;
	return r;
}

int fdclose( const int fd )
{
	return close (fd);
}

Thanks in advance!

[limo]

int tcp_init_server(const int port)

Rewrite this to

int tcp_init_server(const int port, struct* sockaddr_in serv)

then in your tcp_init_server, remove the line

struct sockaddr_in serv; /* this goes out of scope */

You'll also have to change the dot operator in this segment of code to use the -> operator instead

serv.sin_family = PF_INET;
serv.sin_addr.s_addr = htonl ( INADDR_ANY );
serv.sin_port = htons ( port );
rc = bind( sd, (struct sockaddr *)&serv, sizeof(serv) );

to

serv->sin_family = PF_INET;

...
and

rc = bind( sd, serv, sizeof(serv) );

then modify int tcp_server_accept(const int sd) to take in cli as a pointer as well

[robdapeepschamp]

Thanks for the input. I tried implementing those changes, and I get undeclared variable errors for 'serv' and 'cli'??

[limo]

Originally Posted by robdapeepschamp

Thanks for the input. I tried implementing those changes, and I get undeclared variable errors for 'serv' and 'cli'??

Did you define the classes for sockaddr_in and include the definitions in a header file??

i.e.
struct sockaddr_in
{
//blah blah
};