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Re: [libmicrohttpd] [PATCH] Add support for using a monotonic clock for
From: |
Christian Grothoff |
Subject: |
Re: [libmicrohttpd] [PATCH] Add support for using a monotonic clock for timeouts |
Date: |
Tue, 19 Jun 2012 19:50:55 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20120506 Lightning/1.0b1 Icedove/3.0.11 |
Dear Mike,
Thanks for your patches. I've committed all 3 of them in SVN 22116
(first two) and SVN 22117 (this one) respectively, so they will be part
of the next release.
Happy hacking!
Christian
On 06/19/2012 06:50 PM, Mike Crowe wrote:
> Change various uses of time(NULL) to new MHD_monotonic_time() function to
> make timeouts immune to the system real time clock changing. Leave one call
> to time(2) which continues to use the real time for the HTTP Date: header.
>
> If clock_gettime does not support CLOCK_MONOTONIC then fall through to
> calling time(NULL) instead. This will be problematic if clock_gettime
> sometimes fails and sometimes succeeds but that shouldn't happen.
>
> The autoconf magic was lifted from
> http://lists.gnu.org/archive/html/autoconf/2010-08/msg00035.html
> ---
> configure.ac | 3 +++
> src/daemon/connection.c | 6 +++---
> src/daemon/connection_https.c | 4 ++--
> src/daemon/daemon.c | 7 +++----
> src/daemon/digestauth.c | 4 ++--
> src/daemon/internal.c | 10 ++++++++++
> src/daemon/internal.h | 6 ++++++
> 7 files changed, 29 insertions(+), 11 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 41d5472..7b47278 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -190,6 +190,9 @@
> AC_CHECK_HEADERS([plibc.h],our_private_plibc_h=0,our_private_plibc_h=1)
> AM_CONDITIONAL(USE_PRIVATE_PLIBC_H, test x$our_private_plibc_h = x1)
>
> AC_CHECK_FUNCS(memmem)
> +AC_SEARCH_LIBS([clock_gettime], [rt], [
> + AC_DEFINE(HAVE_CLOCK_GETTIME, 1, [Have
> clock_gettime])
> +])
>
> # IPv6
> AC_MSG_CHECKING(for IPv6)
> diff --git a/src/daemon/connection.c b/src/daemon/connection.c
> index acc4839..13c465b 100644
> --- a/src/daemon/connection.c
> +++ b/src/daemon/connection.c
> @@ -1786,7 +1786,7 @@ parse_connection_headers (struct MHD_Connection
> *connection)
> int
> MHD_connection_handle_read (struct MHD_Connection *connection)
> {
> - connection->last_activity = time (NULL);
> + connection->last_activity = MHD_monotonic_time();
> if (connection->state == MHD_CONNECTION_CLOSED)
> return MHD_YES;
> /* make sure "read" has a reasonable number of bytes
> @@ -1851,7 +1851,7 @@ MHD_connection_handle_write (struct MHD_Connection
> *connection)
> {
> struct MHD_Response *response;
> int ret;
> - connection->last_activity = time (NULL);
> + connection->last_activity = MHD_monotonic_time();
> while (1)
> {
> #if DEBUG_STATES
> @@ -2372,7 +2372,7 @@ MHD_connection_handle_idle (struct MHD_Connection
> *connection)
> }
> timeout = connection->connection_timeout;
> if ( (timeout != 0) &&
> - (timeout <= (time (NULL) - connection->last_activity)) )
> + (timeout <= (MHD_monotonic_time() - connection->last_activity)) )
> {
> MHD_connection_close (connection,
> MHD_REQUEST_TERMINATED_TIMEOUT_REACHED);
> return MHD_YES;
> diff --git a/src/daemon/connection_https.c b/src/daemon/connection_https.c
> index 1330c3a..539b8de 100644
> --- a/src/daemon/connection_https.c
> +++ b/src/daemon/connection_https.c
> @@ -47,7 +47,7 @@ run_tls_handshake (struct MHD_Connection *connection)
> {
> int ret;
>
> - connection->last_activity = time (NULL);
> + connection->last_activity = MHD_monotonic_time();
> if (connection->state == MHD_TLS_CONNECTION_INIT)
> {
> ret = gnutls_handshake (connection->tls_session);
> @@ -138,7 +138,7 @@ MHD_tls_connection_handle_idle (struct MHD_Connection
> *connection)
> __FUNCTION__, MHD_state_to_string (connection->state));
> #endif
> timeout = connection->connection_timeout;
> - if ( (timeout != 0) && (time (NULL) - timeout > connection->last_activity))
> + if ( (timeout != 0) && (MHD_monotonic_time() - timeout >
> connection->last_activity))
> MHD_connection_close (connection,
> MHD_REQUEST_TERMINATED_TIMEOUT_REACHED);
> switch (connection->state)
> diff --git a/src/daemon/daemon.c b/src/daemon/daemon.c
> index 29d7ced..451bb39 100644
> --- a/src/daemon/daemon.c
> +++ b/src/daemon/daemon.c
> @@ -546,7 +546,6 @@ MHD_get_fdset (struct MHD_Daemon *daemon,
> return MHD_YES;
> }
>
> -
> /**
> * Main function of the thread that handles an individual
> * connection when MHD_USE_THREAD_PER_CONNECTION is set.
> @@ -578,7 +577,7 @@ MHD_handle_connection (void *data)
> tvp = NULL;
> if (timeout > 0)
> {
> - now = time (NULL);
> + now = MHD_monotonic_time();
> if (now - con->last_activity > timeout)
> tv.tv_sec = 0;
> else
> @@ -938,7 +937,7 @@ MHD_add_connection (struct MHD_Daemon *daemon,
> connection->addr_len = addrlen;
> connection->socket_fd = client_socket;
> connection->daemon = daemon;
> - connection->last_activity = time (NULL);
> + connection->last_activity = MHD_monotonic_time();
>
> /* set default connection handlers */
> MHD_set_http_callbacks_ (connection);
> @@ -1252,7 +1251,7 @@ MHD_get_timeout (struct MHD_Daemon *daemon,
> }
> if (!have_timeout)
> return MHD_NO;
> - now = time (NULL);
> + now = MHD_monotonic_time();
> if (earliest_deadline < now)
> *timeout = 0;
> else
> diff --git a/src/daemon/digestauth.c b/src/daemon/digestauth.c
> index 1e976bb..1f9547c 100644
> --- a/src/daemon/digestauth.c
> +++ b/src/daemon/digestauth.c
> @@ -619,7 +619,7 @@ MHD_digest_auth_check(struct MHD_Connection *connection,
>
> /* 8 = 4 hexadecimal numbers for the timestamp */
> nonce_time = strtoul(nonce + len - 8, (char **)NULL, 16);
> - t = (uint32_t) time(NULL);
> + t = (uint32_t) MHD_monotonic_time();
> /*
> * First level vetting for the nonce validity if the timestamp
> * attached to the nonce exceeds `nonce_timeout' then the nonce is
> @@ -751,7 +751,7 @@ MHD_queue_auth_fail_response(struct MHD_Connection
> *connection,
> char nonce[HASH_MD5_HEX_LEN + 9];
>
> /* Generating the server nonce */
> - calculate_nonce ((uint32_t) time(NULL),
> + calculate_nonce ((uint32_t) MHD_monotonic_time(),
> connection->method,
> connection->daemon->digest_auth_random,
> connection->daemon->digest_auth_rand_size,
> diff --git a/src/daemon/internal.c b/src/daemon/internal.c
> index 3b0a544..453634e 100644
> --- a/src/daemon/internal.c
> +++ b/src/daemon/internal.c
> @@ -157,4 +157,14 @@ MHD_http_unescape (void *cls,
> return wpos - val; /* = strlen(val) */
> }
>
> +time_t MHD_monotonic_time(void)
> +{
> +#ifdef HAVE_CLOCK_GETTIME
> + struct timespec ts;
> + if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
> + return ts.tv_sec;
> +#endif
> + return time(NULL);
> +}
> +
> /* end of internal.c */
> diff --git a/src/daemon/internal.h b/src/daemon/internal.h
> index 6e15af2..15900f1 100644
> --- a/src/daemon/internal.h
> +++ b/src/daemon/internal.h
> @@ -1057,5 +1057,11 @@ struct MHD_Daemon
> (element)->next = NULL; \
> (element)->prev = NULL; } while (0)
>
> +/**
> + * Equivalent to time(NULL) but tries to use some sort of monotonic
> + * clock that isn't affected by someone setting the system real time
> + * clock.
> + */
> +time_t MHD_monotonic_time(void);
>
> #endif