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Simplify random port allocation, and add net.inet.ip.portrange.randomized,

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which can be used to turn off randomized port allocation if so desired.

Requested by:	alfred
This commit is contained in:
Mike Silbersack 2004-04-22 08:32:14 +00:00
parent b1084a1e96
commit 6ac48b7409
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=128547
1 changed files with 13 additions and 27 deletions
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40
sys/netinet/in_pcb.c
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@ -97,6 +97,9 @@ int ipport_hilastauto = IPPORT_HILASTAUTO; /* 65535 */
int ipport_reservedhigh = IPPORT_RESERVED - 1; /* 1023 */
int ipport_reservedlow = 0;
/* Shall we allocate ephemeral ports in random order? */
int ipport_randomized = 1;
#define RANGECHK(var, min, max) \
if ((var) < (min)) { (var) = (min); } \
else if ((var) > (max)) { (var) = (max); }
@ -138,6 +141,8 @@ SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, reservedhigh,
CTLFLAG_RW|CTLFLAG_SECURE, &ipport_reservedhigh, 0, "");
SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, reservedlow,
CTLFLAG_RW|CTLFLAG_SECURE, &ipport_reservedlow, 0, "");
SYSCTL_INT(_net_inet_ip_portrange, OID_AUTO, randomized,
CTLFLAG_RW, &ipport_randomized, 0, "");
/*
* in_pcb.c: manage the Protocol Control Blocks.
@ -377,7 +382,7 @@ in_pcbbind_setup(inp, nam, laddrp, lportp, cred)
if (*lportp != 0)
lport = *lportp;
if (lport == 0) {
u_short first, last, old;
u_short first, last;
int count, loopcount;
if (laddr.s_addr != INADDR_ANY)
@ -406,27 +411,17 @@ in_pcbbind_setup(inp, nam, laddrp, lportp, cred)
* We split the two cases (up and down) so that the direction
* is not being tested on each round of the loop.
*/
loopcount = old = 0;
portloop:
loopcount = 0;
if (first > last) {
/*
* counting down
*/
if (loopcount == 0) { /* only do this once */
old = first;
first -= (arc4random() % (first - last));
}
if (ipport_randomized)
*lastport = first - (arc4random() % (first - last));
count = first - last;
*lastport = first; /* restart each time */
do {
if (count-- < 0) { /* completely used? */
if (loopcount == 0) {
last = old;
loopcount++;
goto portloop;
}
if (count-- < 0) /* completely used? */
return (EADDRNOTAVAIL);
}
--*lastport;
if (*lastport > first || *lastport < last)
*lastport = first;
@ -437,21 +432,12 @@ in_pcbbind_setup(inp, nam, laddrp, lportp, cred)
/*
* counting up
*/
if (loopcount == 0) { /* only do this once. */
old = first;
first += (arc4random() % (last - first));
}
if (ipport_randomized)
*lastport = first + (arc4random() % (last - first));
count = last - first;
*lastport = first; /* restart each time */
do {
if (count-- < 0) { /* completely used? */
if (loopcount == 0) {
first = old;
loopcount++;
goto portloop;
}
if (count-- < 0) /* completely used? */
return (EADDRNOTAVAIL);
}
++*lastport;
if (*lastport < first || *lastport > last)
*lastport = first;