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unix: support full TCP keep-alive on Solaris (#4272)

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Solaris claimed it supported the TCP-Alives mechanism,
but TCP_KEEPIDLE, TCP_KEEPINTVL, and TCP_KEEPCNT were not
available on Solaris until the latest version 11.4.
Therefore, we need to simulate the TCP-Alives mechanism on
other platforms via TCP_KEEPALIVE_THRESHOLD + TCP_KEEPALIVE_ABORT_THRESHOLD.
This commit is contained in:
Andy Pan 2024-01-06 17:46:47 +08:00 committed by GitHub
parent e72a91e063
commit a9381cdb03
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1 changed files with 69 additions and 6 deletions
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src/unix/tcp.c
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@ -453,26 +453,89 @@ int uv__tcp_nodelay(int fd, int on) {
int uv__tcp_keepalive(int fd, int on, unsigned int delay) {
int idle;
int intvl;
int cnt;
(void) &idle;
(void) &intvl;
(void) &cnt;
if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)))
return UV__ERR(errno);
if (!on)
return 0;
if (delay == 0)
return -1;
/* The implementation of TCP keep-alive on Solaris/SmartOS is a bit unusual
* compared to other Unix-like systems.
* Thus, we need to specialize it on Solaris. */
#ifdef __sun
/* There are two keep-alive mechanisms on Solaris:
* - By default, the first keep-alive probe is sent out after a TCP connection is idle for two hours.
* If the peer does not respond to the probe within eight minutes, the TCP connection is aborted.
* You can alter the interval for sending out the first probe using the socket option TCP_KEEPALIVE_THRESHOLD
* in milliseconds or TCP_KEEPIDLE in seconds.
* The system default is controlled by the TCP ndd parameter tcp_keepalive_interval. The minimum value is ten seconds.
* The maximum is ten days, while the default is two hours. If you receive no response to the probe,
* you can use the TCP_KEEPALIVE_ABORT_THRESHOLD socket option to change the time threshold for aborting a TCP connection.
* The option value is an unsigned integer in milliseconds. The value zero indicates that TCP should never time out and
* abort the connection when probing. The system default is controlled by the TCP ndd parameter tcp_keepalive_abort_interval.
* The default is eight minutes.
*
* - The second implementation is activated if socket option TCP_KEEPINTVL and/or TCP_KEEPCNT are set.
* The time between each consequent probes is set by TCP_KEEPINTVL in seconds.
* The minimum value is ten seconds. The maximum is ten days, while the default is two hours.
* The TCP connection will be aborted after certain amount of probes, which is set by TCP_KEEPCNT, without receiving response.
*/
idle = delay;
/* Kernel expects at least 10 seconds. */
if (idle < 10)
idle = 10;
/* Kernel expects at most 10 days. */
if (idle > 10*24*60*60)
idle = 10*24*60*60;
/* `TCP_KEEPIDLE`, `TCP_KEEPINTVL`, and `TCP_KEEPCNT` were not available on Solaris
* until version 11.4, but let's take a chance here. */
#if defined(TCP_KEEPIDLE) && defined(TCP_KEEPINTVL) && defined(TCP_KEEPCNT)
if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, &idle, sizeof(idle)))
return UV__ERR(errno);
intvl = idle/3;
if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPINTVL, &intvl, sizeof(intvl)))
return UV__ERR(errno);
cnt = 3;
if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPCNT, &cnt, sizeof(cnt)))
return UV__ERR(errno);
return 0;
#endif
/* Fall back to the first implementation of tcp-alive mechanism for older Solaris,
* simulate the tcp-alive mechanism on other platforms via `TCP_KEEPALIVE_THRESHOLD` + `TCP_KEEPALIVE_ABORT_THRESHOLD`.
*/
idle *= 1000; /* kernel expects milliseconds */
if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPALIVE_THRESHOLD, &idle, sizeof(idle)))
return UV__ERR(errno);
/* Note that the consequent probes will not be sent at equal intervals on Solaris,
* but will be sent using the exponential backoff algorithm. */
intvl = idle/3;
cnt = 3;
int time_to_abort = intvl * cnt;
if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPALIVE_ABORT_THRESHOLD, &time_to_abort, sizeof(time_to_abort)))
return UV__ERR(errno);
return 0;
#endif
#ifdef TCP_KEEPIDLE
if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE, &delay, sizeof(delay)))
return UV__ERR(errno);
/* Solaris/SmartOS, if you don't support keep-alive,
* then don't advertise it in your system headers...
*/
/* FIXME(bnoordhuis) That's possibly because sizeof(delay) should be 1. */
#elif defined(TCP_KEEPALIVE) && !defined(__sun)
#elif defined(TCP_KEEPALIVE)
if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPALIVE, &delay, sizeof(delay)))
return UV__ERR(errno);
#endif