samba - Sep 1999 - A little utility for checking socket settings

I've been in discussion with a colleague who had to reduce (!)
SO_SNDBUF to get decent performance, and so wrote this little tool.
  It tells you the system default for most of the settable socket
options.  It can't do linger, as the value is a struct instead of
an int, but that's probably uninteresting to Samba folks.

  Run this to see what you'd have if you didn't set any tcp options.

  Written from Stevens TCP/IP Illustrated and man pages, so it's
probably
portable, but only tested on Solaris 7.

--dave




/*
 * getsocketopts -- get the defaults
 *
 * This (on a Solaris 7 system) should say:
 * % su root -c ./getsockopts
 * Default SO_ACCEPTCON: accepting connections = 0
 * Default SO_BROADCAST, broadcast allowed = 0
 * Default SO_REUSEADDR, address recycling = 0
 * Default SO_KEEPALIVE, send keepalive packets = 0
 * Default SO_OOBINLINE, oob data folded inline = 0
 * Default SO_SNDBUF, send buffer size = 8192
 * getsocketopts: could not test SO_RCVLOWAT, receive low-water mark
 * getsocketopts: could not test SO_SNDLOWAT, send low-water mark
 * getsocketopts: could not test SO_RCVTIMEO, receive timeout
 * getsocketopts: could not test SO_SNDTIMEO, send timeout
 * Default SO_RCVBUF, receive buffer size = 32768
 * Default SO_ERROR, error status = 0
 * Default SO_TYPE, socket type = 2
 * Default TCP_MAXSEG, maximum segment size (mss) = 536
 * Default TCP_NODELAY, send even tiny packets = 0
 */
#include <stdio.h>
#include <sys/types.h> /* for getuid() */
#include <unistd.h>
#include <sys/socket.h> /* For socket() */
#include <netinet/in.h> /* For protocol numbers. */
#include <netinet/tcp.h>   /* For options. */

typedef struct option_t {
        int name;
        char *printable;
} OPTION;


main() {
        int s;
        OPTION so_option[] = {
                { SO_ACCEPTCONN, "SO_ACCEPTCON: accepting connections"
},
                { SO_BROADCAST, "SO_BROADCAST, broadcast allowed" },
                { SO_REUSEADDR, "SO_REUSEADDR, address recycling" },
                { SO_KEEPALIVE, "SO_KEEPALIVE, send keepalive packets"
},
                /* { SO_LINGER, "SO_LINGER, lingers on close"}, */
                { SO_OOBINLINE, "SO_OOBINLINE, oob data folded
inline"},
                { SO_SNDBUF, "SO_SNDBUF, send buffer size" },
                { SO_RCVLOWAT, "SO_RCVLOWAT, receive low-water mark"},
                { SO_SNDLOWAT, "SO_SNDLOWAT, send low-water mark"},
                { SO_RCVTIMEO, "SO_RCVTIMEO, receive timeout"},
                { SO_SNDTIMEO, "SO_SNDTIMEO, send timeout"},
                { SO_RCVBUF, "SO_RCVBUF, receive buffer size"},
                { SO_ERROR, "SO_ERROR, error status"},
                { SO_TYPE, "SO_TYPE, socket type"},
                { 0, NULL }
        };
        OPTION tcp_option[] = {
                  { TCP_MAXSEG, "TCP_MAXSEG, maximum segment size
(mss)"},
                  { TCP_NODELAY, "TCP_NODELAY, send even tiny
packets"},
                  { 0, NULL}
        };

        if ((getuid()) != 0) {
                (void) fprintf(stderr,"getsocketopts: you must be root
first.\n");
                (void) exit(1);
        }

        if ((s = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP)) == -1) {
                perror("failed in socket call,");
                (void) exit(1);
        }
        query(s, SOL_SOCKET, so_option);
        query(s, IPPROTO_TCP, tcp_option);

        (void) close(s);
        (void) exit(0);
}

query(int s, int type, OPTION *p) {
        int value, vlen = 4;

        for (; p->printable != NULL; p++) {
                if (getsockopt(s, type, p->name, (void *)&value,
&vlen) == -1) {
                        (void) fprintf(stderr,"getsocketopts: could
not test %s\n", p->printable);
                }
                else {
                        (void) printf("Default %s = %d\n",
p->printable,value);
                }
        }
}

David Collier-Brown wrote:
>  I've been in discussion with a colleague who had to reduce (!)
> SO_SNDBUF to get decent performance

	The program needed some #ifdef's for Linux (thanks, tridge!)
	so here's a re-write and a Linux result from 2.2.12:
Default SO_BROADCAST, broadcast allowed = 0
Default SO_REUSEADDR, address recycling = 0
Default SO_KEEPALIVE, send keepalive packets = 0
Default SO_OOBINLINE, oob data folded inline = 0
Default SO_SNDBUF, send buffer size = 65535 
Default SO_RCVLOWAT, receive low-water mark = 1
Default SO_SNDLOWAT, send low-water mark = 1
Default SO_RCVTIMEO, receive timeout = 0
Default SO_SNDTIMEO, send timeout = 0
Default SO_RCVBUF, receive buffer size = 65535
Default SO_ERROR, error status = 0
Default SO_TYPE, socket type = 1
Default TCP_MAXSEG, maximum segment size (mss) = 0
Default TCP_NODELAY, send even tiny packets = 0

--dave
-------------- next part --------------
/*
 * getsocketopts -- get the defaults
 *
 * This (on a Solaris 7 system) should say:
 * % su root -c ./getsockopts
 * Default SO_ACCEPTCON: accepting connections = 0
 * Default SO_BROADCAST, broadcast allowed = 0
 * Default SO_REUSEADDR, address recycling = 0
 * Default SO_KEEPALIVE, send keepalive packets = 0
 * Default SO_OOBINLINE, oob data folded inline = 0
 * Default SO_SNDBUF, send buffer size = 8192
 * getsocketopts: could not test SO_RCVLOWAT, receive low-water mark
 * getsocketopts: could not test SO_SNDLOWAT, send low-water mark
 * getsocketopts: could not test SO_RCVTIMEO, receive timeout
 * getsocketopts: could not test SO_SNDTIMEO, send timeout
 * Default SO_RCVBUF, receive buffer size = 32768
 * Default SO_ERROR, error status = 0
 * Default SO_TYPE, socket type = 2
 * Default TCP_MAXSEG, maximum segment size (mss) = 536
 * Default TCP_NODELAY, send even tiny packets = 0
 */


#include <stdio.h>
#include <stdlib.h> /* For defn' of exit(). */
#include <sys/types.h> /* for getuid() */
#include <unistd.h>
#include <sys/socket.h> /* For socket() */
#include <netinet/in.h> /* For protocol numbers. */
#include <netinet/tcp.h>   /* For options. */

typedef struct option_t {
	int name;
	char *printable;
} OPTION;

void query(int, int, OPTION *);

OPTION so_option[] = {
#ifdef SO_ACCEPTCONN
	{ SO_ACCEPTCONN, "SO_ACCEPTCON: accepting connections" },
#endif
#ifdef SO_BROADCAST
	{ SO_BROADCAST, "SO_BROADCAST, broadcast allowed" },
#endif
#ifdef SO_REUSEADDR
	{ SO_REUSEADDR, "SO_REUSEADDR, address recycling" },
#endif
#ifdef SO_KEEPALIVE
	{ SO_KEEPALIVE, "SO_KEEPALIVE, send keepalive packets" },
#endif
	/* { SO_LINGER, "SO_LINGER, lingers on close"}, */
#ifdef SO_OOBINLINE
	{ SO_OOBINLINE, "SO_OOBINLINE, oob data folded inline"},
#endif
#ifdef SO_SNDBUF
	{ SO_SNDBUF, "SO_SNDBUF, send buffer size" },
#endif
#ifdef SO_RCVLOWAT
	{ SO_RCVLOWAT, "SO_RCVLOWAT, receive low-water mark"},
#endif
#ifdef SO_SNDLOWAT
	{ SO_SNDLOWAT, "SO_SNDLOWAT, send low-water mark"},
#endif
#ifdef SO_RCVTIMEO
	{ SO_RCVTIMEO, "SO_RCVTIMEO, receive timeout"},
#endif
#ifdef SO_SNDTIMEO
	{ SO_SNDTIMEO, "SO_SNDTIMEO, send timeout"},
#endif
#ifdef SO_RCVBUF
	{ SO_RCVBUF, "SO_RCVBUF, receive buffer size"},
#endif
#ifdef SO_ERROR
	{ SO_ERROR, "SO_ERROR, error status"},
#endif
#ifdef SO_TYPE
	{ SO_TYPE, "SO_TYPE, socket type"},
#endif
	{ 0, NULL }
};

OPTION tcp_option[] = {
#ifdef TCP_MAXSEG
	  { TCP_MAXSEG, "TCP_MAXSEG, maximum segment size (mss)"},
#endif
#ifdef TCP_NODELAY
	  { TCP_NODELAY, "TCP_NODELAY, send even tiny packets"},
#endif
	  { 0, NULL}
};



main() {
	int s;
	if ((getuid()) != 0) {
		(void) fprintf(stderr,"getsocketopts: you must be root first.\n");
		(void) exit(1);
	}

	if ((s = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP)) == -1) {
		perror("failed in socket call,");
		(void) exit(1);
	}
	query(s, SOL_SOCKET, so_option);
	query(s, IPPROTO_TCP, tcp_option);

	(void) close(s);
	(void) exit(0);
	/*NOTREACHED*/
}

/*
 * query -- see about one option
 */
 void
query(int s, int type, OPTION *p) {
	int value, vlen = 4;

	for (; p->printable != NULL; p++) {
		if (getsockopt(s, type, p->name, (void *)&value, &vlen) == -1) {
			(void) fprintf(stderr,"getsocketopts: could not test %s\n",
		       p->printable);
		}
		else {
			(void) printf("Default %s = %d\n",p->printable,value);
		}
	}
}