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/*
* Copyright (c) 2018, Oracle America, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* - Neither the name of "Oracle America, Inc." nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <syslog.h>
#include <rpc/rpc.h>
#include "reentrant.h"
#include "rpc_com.h"
extern pthread_mutex_t port_lock;
/*
* Dynamic port range as defined in RFC 6335 Section 6.
* This range avoids all IANA-assigned service port
* numbers.
*/
enum {
LOWPORT = 49152,
ENDPORT = 65534,
NPORTS = ENDPORT - LOWPORT + 1,
};
/*
* This function decodes information about given port from provided array and
* return if port is reserved or not.
*
* @reserved_ports an array of size at least "NPORTS / (8*sizeof(char)) + 1".
* @port port number within range LOWPORT and ENDPORT
*
* Returns 0 if port is not reserved, non-negative if port is reserved.
*/
static int is_reserved(char *reserved_ports, int port) {
port -= LOWPORT;
if (port < 0 || port >= NPORTS)
return 0;
return reserved_ports[port/(8*sizeof(char))] & 1<<(port%(8*sizeof(char)));
}
/*
* This function encodes information about given *reserved* port into provided
* array. Don't call this function for ports which are not reserved.
*
* @reserved_ports an array of size at least "NPORTS / (8*sizeof(char)) + 1".
* @port port number within range LOWPORT and ENDPORT
*
*/
static void set_reserved(char *reserved_ports, int port) {
port -= LOWPORT;
if (port < 0 || port >= NPORTS)
return;
reserved_ports[port/(8*sizeof(char))] |= 1<<(port%(8*sizeof(char)));
}
/*
* Parse local reserved ports obtained from
* /proc/sys/net/ipv4/ip_local_reserved_ports into bit array.
*
* @reserved_ports a zeroed array of size at least
* "NPORTS / (8*sizeof(char)) + 1". Will be used for bit-wise encoding of
* reserved ports.
*
* On each call, reserved ports are read from /proc and bit-wise stored into
* provided array
*
* Returns 0 on success, -1 on failure.
*/
static int parse_reserved_ports(char *reserved_ports) {
int from=0, to;
char delimiter = ',';
int res;
FILE * file_ptr = fopen("/proc/sys/net/ipv4/ip_local_reserved_ports","r");
if (file_ptr == NULL) {
(void) syslog(LOG_ERR,
"Unable to open open /proc/sys/net/ipv4/ip_local_reserved_ports.");
return -1;
}
do {
if ((res = fscanf(file_ptr, "%d", &to)) != 1) {
if (res == EOF) break;
goto err;
}
if (delimiter != '-') {
from = to;
}
for (int i = from; i <= to; ++i) {
set_reserved(reserved_ports, i);
}
} while ((res = fscanf(file_ptr, "%c", &delimiter)) == 1);
if (res != EOF)
goto err;
fclose(file_ptr);
return 0;
err:
(void) syslog(LOG_ERR,
"An error occurred while parsing ip_local_reserved_ports.");
fclose(file_ptr);
return -1;
}
/*
* Bind a socket to a dynamically-assigned IP port.
*
* @fd is an open but unbound socket.
*
* On each call, a port number is chosen at random from
* within the dynamic/private port range, even if the
* caller has CAP_NET_ADMIN_BIND.
*
* Returns 0 on success, -1 on failure. errno may be
* set to a non-determinant value.
*
* This function is re-entrant.
*/
int __binddynport(int fd)
{
struct sockaddr_storage ss;
#ifdef INET6
struct sockaddr_in6 *sin6;
#endif
struct sockaddr_in *sin;
static unsigned int seed;
in_port_t port, *portp;
struct sockaddr *sap;
socklen_t salen;
int i, res, array_size;
char *reserved_ports = NULL;
if (__rpc_sockisbound(fd))
return 0;
res = -1;
sap = (struct sockaddr *)(void *)&ss;
salen = sizeof(ss);
memset(sap, 0, salen);
mutex_lock(&port_lock);
if (getsockname(fd, sap, &salen) == -1)
goto out;
switch (ss.ss_family) {
case AF_INET:
sin = (struct sockaddr_in *)(void *)&ss;
portp = &sin->sin_port;
salen = sizeof(struct sockaddr_in);
break;
#ifdef INET6
case AF_INET6:
sin6 = (struct sockaddr_in6 *)(void *)&ss;
portp = &sin6->sin6_port;
salen = sizeof(struct sockaddr_in6);
break;
#endif
default:
goto out;
}
if (!seed) {
struct timeval tv;
gettimeofday(&tv, NULL);
seed = tv.tv_usec * getpid();
}
array_size = NPORTS / (8*sizeof(char)) + 1;
reserved_ports = malloc(array_size);
if (!reserved_ports) {
goto out;
}
memset(reserved_ports, 0, array_size);
if (parse_reserved_ports(reserved_ports) < 0)
goto out;
port = (rand_r(&seed) % NPORTS) + LOWPORT;
for (i = 0; i < NPORTS; ++i) {
*portp = htons(port);
if (!is_reserved(reserved_ports, port++)) {
res = bind(fd, sap, salen);
if (res >= 0) {
res = 0;
break;
}
if (errno != EADDRINUSE)
break;
}
if (port > ENDPORT)
port = LOWPORT;
}
out:
free(reserved_ports);
mutex_unlock(&port_lock);
return res;
}
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