upkeep: add a connection upkeep API: curl_easy_conn_upkeep()

Add functionality so that protocols can do custom keepalive on their
connections, when an external API function is called.

Add docs for the new options in 7.62.0

Closes #1641
This commit is contained in:
Max Dymond 2018-04-18 16:40:17 +01:00 committed by Daniel Stenberg
parent 6684653b68
commit 7b655fcbad
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15 changed files with 280 additions and 2 deletions

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@ -22,4 +22,4 @@ man_MANS = curl_easy_cleanup.3 curl_easy_getinfo.3 curl_easy_init.3 \
curl_mime_data.3 curl_mime_data_cb.3 curl_mime_filedata.3 \
curl_mime_filename.3 curl_mime_subparts.3 \
curl_mime_type.3 curl_mime_headers.3 curl_mime_encoder.3 libcurl-env.3 \
libcurl-security.3
libcurl-security.3 curl_easy_conn_upkeep.3

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@ -0,0 +1,77 @@
.\" **************************************************************************
.\" * _ _ ____ _
.\" * Project ___| | | | _ \| |
.\" * / __| | | | |_) | |
.\" * | (__| |_| | _ <| |___
.\" * \___|\___/|_| \_\_____|
.\" *
.\" * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
.\" *
.\" * This software is licensed as described in the file COPYING, which
.\" * you should have received as part of this distribution. The terms
.\" * are also available at https://curl.haxx.se/docs/copyright.html.
.\" *
.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
.\" * copies of the Software, and permit persons to whom the Software is
.\" * furnished to do so, under the terms of the COPYING file.
.\" *
.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
.\" * KIND, either express or implied.
.\" *
.\" **************************************************************************
.\"
.TH curl_easy_conn_upkeep 3 "31 Oct 2018" "libcurl 7.62.0" "libcurl Manual"
.SH NAME
curl_easy_conn_upkeep - Perform any connection upkeep checks.
.SH SYNOPSIS
.B #include <curl/curl.h>
.BI "CURLcode curl_easy_conn_upkeep(CURL *" handle ");"
.SH DESCRIPTION
Some protocols have "connection upkeep" mechanisms. These mechanisms usually
send some traffic on existing connections in order to keep them alive; this
can prevent connections from being closed due to overzealous firewalls, for
example.
Currently the only protocol with a connection upkeep mechanism is HTTP/2: when
the connection upkeep interval is exceeded and \fIcurl_easy_conn_upkeep(3)\fP
is called, an HTTP/2 PING frame is sent on the connection.
This function must be explicitly called in order to perform the upkeep work.
The connection upkeep interval is set with
\fICURLOPT_CONN_UPKEEP_INTERVAL_MS(3)\fP.
.SH AVAILABILITY
Added in 7.62.0.
.SH RETURN VALUE
On success, returns \fBCURLE_OK\fP.
On failure, returns the appropriate error code.
.SH EXAMPLE
.nf
CURL *curl = curl_easy_init();
if(curl) {
/* Make a connection to an HTTP/2 server. */
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
/* Set the interval to 30000ms / 30s */
curl_easy_setopt(curl, CURLOPT_CONN_UPKEEP_INTERVAL_MS, 30000L);
curl_easy_perform(curl);
/* Perform more work here. */
/* While the connection is being held open, curl_easy_conn_upkeep() can be
called. If curl_easy_conn_upkeep() is called and the time since the last
upkeep exceeds the interval, then an HTTP/2 PING is sent. */
curl_easy_conn_upkeep(curl);
/* Perform more work here. */
/* always cleanup */
curl_easy_cleanup(curl);
}
.fi

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@ -480,6 +480,9 @@ Shuffle addresses before use. See \fICURLOPT_DNS_SHUFFLE_ADDRESSES(3)\fP
Timeout for waiting for the server's connect back to be accepted. See \fICURLOPT_ACCEPTTIMEOUT_MS(3)\fP
.IP CURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS
Timeout for happy eyeballs. See \fICURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS(3)\fP
.IP CURLOPT_CONN_UPKEEP_INTERVAL_MS
Sets the interval at which connection upkeep are performed. See
\fICURLOPT_CONN_UPKEEP_INTERVAL_MS(3)\fP
.SH SSL and SECURITY OPTIONS
.IP CURLOPT_SSLCERT
Client cert. See \fICURLOPT_SSLCERT(3)\fP

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@ -0,0 +1,73 @@
.\" **************************************************************************
.\" * _ _ ____ _
.\" * Project ___| | | | _ \| |
.\" * / __| | | | |_) | |
.\" * | (__| |_| | _ <| |___
.\" * \___|\___/|_| \_\_____|
.\" *
.\" * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
.\" *
.\" * This software is licensed as described in the file COPYING, which
.\" * you should have received as part of this distribution. The terms
.\" * are also available at https://curl.haxx.se/docs/copyright.html.
.\" *
.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
.\" * copies of the Software, and permit persons to whom the Software is
.\" * furnished to do so, under the terms of the COPYING file.
.\" *
.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
.\" * KIND, either express or implied.
.\" *
.\" **************************************************************************
.\"
.TH CURLOPT_CONN_UPKEEP_INTERVAL_MS 3 "31 Oct 2018" "libcurl 7.62.0" "curl_easy_setopt options"
.SH NAME
CURLOPT_CONN_UPKEEP_INTERVAL_MS \- connection upkeep interval
.SH SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CONN_UPKEEP_INTERVAL_MS, long upkeep_interval_ms);
.SH DESCRIPTION
Some protocols have "connection upkeep" mechanisms. These mechanisms usually
send some traffic on existing connections in order to keep them alive; this
can prevent connections from being closed due to overzealous firewalls, for
example.
The user needs to explicitly call \fIcurl_easy_conn_upkeep(3)\fP in order to
perform the upkeep work.
Currently the only protocol with a connection upkeep mechanism is HTTP/2: when
the connection upkeep interval is exceeded and \fIcurl_easy_conn_upkeep(3)\fP
is called, an HTTP/2 PING frame is sent on the connection.
.SH DEFAULT
CURL_UPKEEP_INTERVAL_DEFAULT (currently defined as 60000L, which is 60 seconds)
.SH EXAMPLE
.nf
CURL *curl = curl_easy_init();
if(curl) {
/* Make a connection to an HTTP/2 server. */
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
/* Set the interval to 30000ms / 30s */
curl_easy_setopt(curl, CURLOPT_CONN_UPKEEP_INTERVAL_MS, 30000L);
curl_easy_perform(curl);
/* Perform more work here. */
/* While the connection is being held open, curl_easy_conn_upkeep() can be
called. If curl_easy_conn_upkeep() is called and the time since the last
upkeep exceeds the interval, then an HTTP/2 PING is sent. */
curl_easy_conn_upkeep(curl);
/* Perform more work here. */
/* always cleanup */
curl_easy_cleanup(curl);
}
.fi
.SH AVAILABILITY
Added in 7.62.0
.SH RETURN VALUE
Returns CURLE_OK

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@ -94,6 +94,7 @@ man_MANS = \
CURLOPT_CHUNK_END_FUNCTION.3 \
CURLOPT_CLOSESOCKETDATA.3 \
CURLOPT_CLOSESOCKETFUNCTION.3 \
CURLOPT_CONN_UPKEEP_INTERVAL_MS.3 \
CURLOPT_CONNECTTIMEOUT.3 \
CURLOPT_CONNECTTIMEOUT_MS.3 \
CURLOPT_CONNECT_ONLY.3 \

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@ -356,6 +356,7 @@ CURLOPT_CLOSEFUNCTION 7.7 7.11.1 7.15.5
CURLOPT_CLOSEPOLICY 7.7 7.16.1
CURLOPT_CLOSESOCKETDATA 7.21.7
CURLOPT_CLOSESOCKETFUNCTION 7.21.7
CURLOPT_CONN_UPKEEP_INTERVAL_MS 7.62.0
CURLOPT_CONNECTTIMEOUT 7.7
CURLOPT_CONNECTTIMEOUT_MS 7.16.2
CURLOPT_CONNECT_ONLY 7.15.2
@ -856,6 +857,7 @@ CURL_TIMECOND_LASTMOD 7.9.7
CURL_TIMECOND_NONE 7.9.7
CURL_TLSAUTH_NONE 7.21.4
CURL_TLSAUTH_SRP 7.21.4
CURL_UPKEEP_INTERVAL_DEFAULT 7.62.0
CURL_VERSION_ASYNCHDNS 7.10.7
CURL_VERSION_BROTLI 7.57.0
CURL_VERSION_CONV 7.15.4

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@ -803,6 +803,9 @@ typedef enum {
this value, keep them in sync. */
#define CURL_HET_DEFAULT 200L
/* The default connection upkeep interval in milliseconds. */
#define CURL_UPKEEP_INTERVAL_DEFAULT 60000L
#ifndef CURL_NO_OLDIES /* define this to test if your app builds with all
the obsolete stuff removed! */
@ -1865,6 +1868,9 @@ typedef enum {
/* Preferred buffer size to use for uploads */
CINIT(UPLOAD_BUFFERSIZE, LONG, 280),
/* Time in ms between connection upkeep calls for long-lived connections. */
CINIT(CONN_UPKEEP_INTERVAL_MS, LONG, 281),
CURLOPT_LASTENTRY /* the last unused */
} CURLoption;

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@ -95,6 +95,16 @@ CURL_EXTERN CURLcode curl_easy_recv(CURL *curl, void *buffer, size_t buflen,
CURL_EXTERN CURLcode curl_easy_send(CURL *curl, const void *buffer,
size_t buflen, size_t *n);
/*
* NAME curl_easy_conn_upkeep()
*
* DESCRIPTION
*
* Performs connection upkeep for the given session handle.
*/
CURL_EXTERN CURLcode curl_easy_conn_upkeep(CURL *curl);
#ifdef __cplusplus
}
#endif

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@ -1197,3 +1197,23 @@ CURLcode curl_easy_send(struct Curl_easy *data, const void *buffer,
return result;
}
/*
* Performs connection upkeep for the given session handle.
*/
CURLcode curl_easy_conn_upkeep(struct Curl_easy *data)
{
/* Verify that we got an easy handle we can work with. */
if(!GOOD_EASY_HANDLE(data))
return CURLE_BAD_FUNCTION_ARGUMENT;
if(data->multi_easy) {
/* Use the common function to keep connections alive. */
return Curl_conn_upkeep(&data->multi_easy->conn_cache, data);
}
else {
/* No connections, so just return success */
return CURLE_OK;
}
}

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@ -233,12 +233,43 @@ static unsigned int http2_conncheck(struct connectdata *check,
unsigned int checks_to_perform)
{
unsigned int ret_val = CONNRESULT_NONE;
struct http_conn *c = &check->proto.httpc;
int rc;
bool send_frames = false;
if(checks_to_perform & CONNCHECK_ISDEAD) {
if(http2_connisdead(check))
ret_val |= CONNRESULT_DEAD;
}
if(checks_to_perform & CONNCHECK_KEEPALIVE) {
struct curltime now = Curl_now();
time_t elapsed = Curl_timediff(now, check->keepalive);
if(elapsed > check->upkeep_interval_ms) {
/* Perform an HTTP/2 PING */
rc = nghttp2_submit_ping(c->h2, 0, ZERO_NULL);
if(!rc) {
/* Successfully added a PING frame to the session. Need to flag this
so the frame is sent. */
send_frames = true;
}
else {
failf(check->data, "nghttp2_submit_ping() failed: %s(%d)",
nghttp2_strerror(rc), rc);
}
check->keepalive = now;
}
}
if(send_frames) {
rc = nghttp2_session_send(c->h2);
if(rc)
failf(check->data, "nghttp2_session_send() failed: %s(%d)",
nghttp2_strerror(rc), rc);
}
return ret_val;
}

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@ -2624,6 +2624,12 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option,
va_arg(param, char *));
data->set.doh = data->set.str[STRING_DOH]?TRUE:FALSE;
break;
case CURLOPT_CONN_UPKEEP_INTERVAL_MS:
arg = va_arg(param, long);
if(arg < 0)
return CURLE_BAD_FUNCTION_ARGUMENT;
data->set.upkeep_interval_ms = arg;
break;
default:
/* unknown tag and its companion, just ignore: */
result = CURLE_UNKNOWN_OPTION;

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@ -529,6 +529,7 @@ CURLcode Curl_init_userdefined(struct Curl_easy *data)
set->upload_buffer_size = UPLOADBUFFER_DEFAULT;
set->happy_eyeballs_timeout = CURL_HET_DEFAULT;
set->fnmatch = ZERO_NULL;
set->upkeep_interval_ms = CURL_UPKEEP_INTERVAL_DEFAULT;
set->maxconnects = DEFAULT_CONNCACHE_SIZE; /* for easy handles */
set->httpversion =
#ifdef USE_NGHTTP2
@ -1831,6 +1832,12 @@ static struct connectdata *allocate_conn(struct Curl_easy *data)
/* Store creation time to help future close decision making */
conn->created = Curl_now();
/* Store current time to give a baseline to keepalive connection times. */
conn->keepalive = Curl_now();
/* Store off the configured connection upkeep time. */
conn->upkeep_interval_ms = data->set.upkeep_interval_ms;
conn->data = data; /* Setup the association between this connection
and the Curl_easy */
@ -4843,3 +4850,34 @@ static unsigned int get_protocol_family(unsigned int protocol)
return family;
}
/*
* Wrapper to call functions in Curl_conncache_foreach()
*
* Returns always 0.
*/
static int conn_upkeep(struct connectdata *conn,
void *param)
{
/* Param is unused. */
(void)param;
if(conn->handler->connection_check) {
/* Do a protocol-specific keepalive check on the connection. */
conn->handler->connection_check(conn, CONNCHECK_KEEPALIVE);
}
return 0; /* continue iteration */
}
CURLcode Curl_conn_upkeep(struct conncache *conn_cache,
void *data)
{
/* Loop over every connection and make connection alive. */
Curl_conncache_foreach(data,
conn_cache,
data,
conn_upkeep);
return CURLE_OK;
}

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@ -77,6 +77,7 @@ int Curl_removeHandleFromPipeline(struct Curl_easy *handle,
void Curl_getoff_all_pipelines(struct Curl_easy *data,
struct connectdata *conn);
CURLcode Curl_conn_upkeep(struct conncache *conn_cache, void *data);
#define CURL_DEFAULT_PROXY_PORT 1080 /* default proxy port unless specified */
#define CURL_DEFAULT_HTTPS_PROXY_PORT 443 /* default https proxy port unless

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@ -729,6 +729,7 @@ struct Curl_handler {
#define CONNCHECK_NONE 0 /* No checks */
#define CONNCHECK_ISDEAD (1<<0) /* Check if the connection is dead. */
#define CONNCHECK_KEEPALIVE (1<<1) /* Perform any keepalive function. */
#define CONNRESULT_NONE 0 /* No extra information. */
#define CONNRESULT_DEAD (1<<0) /* The connection is dead. */
@ -905,6 +906,13 @@ struct connectdata {
long ip_version; /* copied from the Curl_easy at creation time */
/* Protocols can use a custom keepalive mechanism to keep connections alive.
This allows those protocols to track the last time the keepalive mechanism
was used on this connection. */
struct curltime keepalive;
long upkeep_interval_ms; /* Time between calls for connection upkeep. */
/**** curl_get() phase fields */
curl_socket_t sockfd; /* socket to read from or CURL_SOCKET_BAD */
@ -1704,6 +1712,7 @@ struct UserDefined {
before resolver start */
void *resolver_start_client; /* pointer to pass to resolver start callback */
bool disallow_username_in_url; /* disallow username in url */
long upkeep_interval_ms; /* Time between calls for connection upkeep. */
bool doh; /* DNS-over-HTTPS enabled */
bool doh_get; /* use GET for DoH requests, instead of POST */
multidone_func fmultidone;

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@ -16,7 +16,7 @@ none
# The VMS and OS/400 builds extract the CURL_EXTERN protos and use in
# the build. We break binary compatibility by changing order. Only add
# new entries last or bump the SONAME.
#
#
<name>
Verify CURL_EXTERN order
</name>
@ -75,6 +75,7 @@ CURL_EXTERN CURL *curl_easy_duphandle(CURL *curl);
CURL_EXTERN void curl_easy_reset(CURL *curl);
CURL_EXTERN CURLcode curl_easy_recv(CURL *curl, void *buffer, size_t buflen,
CURL_EXTERN CURLcode curl_easy_send(CURL *curl, const void *buffer,
CURL_EXTERN CURLcode curl_easy_conn_upkeep(CURL *curl);
CURL_EXTERN int curl_mprintf(const char *format, ...);
CURL_EXTERN int curl_mfprintf(FILE *fd, const char *format, ...);
CURL_EXTERN int curl_msprintf(char *buffer, const char *format, ...);