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Print more detail as part of the sonewconn() overflow message.

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When a socket's listen queue overflows, sonewconn() emits a debug-level
log message. These messages are sometimes useful to systems administrators
in highlighting a process which is not keeping up with its listen queue.

This commit attempts to enhance the usefulness of this message by printing
more details about the socket's address. If all else fails, it will at
least print the domain name of the socket.

Reviewed by:	bz, jhb, kbowling
MFC after:	2 weeks
Sponsored by:	Netflix, Inc.
Differential Revision:	https://reviews.freebsd.org/D24272
This commit is contained in:
Jonathan T. Looney 2020-04-14 15:30:34 +00:00
parent a5d22a7fed
commit f6ab9795d4
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=359922
1 changed files with 85 additions and 2 deletions
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87
sys/kern/uipc_socket.c
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@ -130,6 +130,7 @@ __FBSDID("$FreeBSD$");
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/protosw.h>
#include <sys/sbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/resourcevar.h>
@ -140,9 +141,12 @@ __FBSDID("$FreeBSD$");
#include <sys/sysctl.h>
#include <sys/taskqueue.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <sys/unpcb.h>
#include <sys/jail.h>
#include <sys/syslog.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/tcp.h>
#include <net/vnet.h>
@ -587,8 +591,17 @@ sonewconn(struct socket *head, int connstatus)
static struct timeval overinterval = { 60, 0 };
static int overcount;
struct sbuf descrsb;
struct socket *so;
u_int over;
int len;
const char localprefix[] = "local:";
char descrbuf[SUNPATHLEN + sizeof(localprefix)];
#if defined(INET6)
char addrbuf[INET6_ADDRSTRLEN];
#elif defined(INET)
char addrbuf[INET_ADDRSTRLEN];
#endif
SOLISTEN_LOCK(head);
over = (head->sol_qlen > 3 * head->sol_qlimit / 2);
@ -601,10 +614,80 @@ sonewconn(struct socket *head, int connstatus)
overcount++;
if (ratecheck(&lastover, &overinterval)) {
log(LOG_DEBUG, "%s: pcb %p: Listen queue overflow: "
/*
* Try to print something descriptive about the
* socket for the error message.
*/
sbuf_new(&descrsb, descrbuf, sizeof(descrbuf),
SBUF_FIXEDLEN);
switch (head->so_proto->pr_domain->dom_family) {
#if defined(INET) || defined(INET6)
#ifdef INET
case AF_INET:
#endif
#ifdef INET6
case AF_INET6:
if (head->so_proto->pr_domain->dom_family ==
AF_INET6 ||
(sotoinpcb(head)->inp_inc.inc_flags &
INC_ISIPV6)) {
ip6_sprintf(addrbuf,
&sotoinpcb(head)->inp_inc.inc6_laddr);
sbuf_printf(&descrsb, "[%s]", addrbuf);
} else
#endif
{
#ifdef INET
inet_ntoa_r(
sotoinpcb(head)->inp_inc.inc_laddr,
addrbuf);
sbuf_cat(&descrsb, addrbuf);
#endif
}
sbuf_printf(&descrsb, ":%hu (proto %u)",
ntohs(sotoinpcb(head)->inp_inc.inc_lport),
head->so_proto->pr_protocol);
break;
#endif /* INET || INET6 */
case AF_UNIX:
sbuf_cat(&descrsb, localprefix);
if (sotounpcb(head)->unp_addr != NULL)
len =
sotounpcb(head)->unp_addr->sun_len -
offsetof(struct sockaddr_un,
sun_path);
else
len = 0;
if (len > 0)
sbuf_bcat(&descrsb,
sotounpcb(head)->unp_addr->sun_path,
len);
else
sbuf_cat(&descrsb, "(unknown)");
break;
}
/*
* If we can't print something more specific, at least
* print the domain name.
*/
if (sbuf_finish(&descrsb) != 0 ||
sbuf_len(&descrsb) <= 0) {
sbuf_clear(&descrsb);
sbuf_cat(&descrsb,
head->so_proto->pr_domain->dom_name ?:
"unknown");
sbuf_finish(&descrsb);
}
KASSERT(sbuf_len(&descrsb) > 0,
("%s: sbuf creation failed", __func__));
log(LOG_DEBUG,
"%s: pcb %p (%s): Listen queue overflow: "
"%i already in queue awaiting acceptance "
"(%d occurrences)\n",
__func__, head->so_pcb, head->sol_qlen, overcount);
__func__, head->so_pcb, sbuf_data(&descrsb),
head->sol_qlen, overcount);
sbuf_delete(&descrsb);
overcount = 0;
}