http2: add option CURLMOPT_STREAM_WINDOW_SIZE to set stream window size

docs/libcurl/curl_easy_pause.3

@@ -80,7 +80,9 @@ this because it needs to drain the socket for the other transfers and the
 already announced window size for the paused transfer will allow the server to
 continue sending data up to that window size amount. By default, libcurl
 announces a 32 megabyte window size, which thus can make libcurl end up
-buffering 32 megabyte of data for a paused stream.
+buffering 32 megabyte of data for a paused stream. The window size can be
+changed with \fICURLOPT_STREAM_WINDOW_SIZE(3)\fP (easy interface) or
+\fICURLMOPT_STREAM_WINDOW_SIZE(3)\fP (multi interface).
 
 When such a paused stream is unpaused again, any buffered data will be
 delivered first.
@@ -109,4 +111,5 @@ CURLE_OK (zero) means that the option was set properly, and a non-zero return
 code means something wrong occurred after the new state was set.  See the
 \fIlibcurl-errors(3)\fP man page for the full list with descriptions.
 .SH "SEE ALSO"
-.BR curl_easy_cleanup "(3), " curl_easy_reset "(3)"
+.BR curl_easy_cleanup "(3), " curl_easy_reset "(3), "
+.BR CURLOPT_STREAM_WINDOW_SIZE "(3), " CURLMOPT_STREAM_WINDOW_SIZE "(3)"

docs/libcurl/curl_easy_setopt.3

@@ -367,6 +367,8 @@ This HTTP/2 stream depends on another exclusively. See
 \fICURLOPT_STREAM_DEPENDS_E(3)\fP
 .IP CURLOPT_STREAM_WEIGHT
 Set this HTTP/2 stream's weight. See \fICURLOPT_STREAM_WEIGHT(3)\fP
+.IP CURLOPT_STREAM_WINDOW_SIZE
+Set the HTTP/2 stream window size. See \fICURLMOPT_STREAM_WINDOW_SIZE(3)\fP
 .SH SMTP OPTIONS
 .IP CURLOPT_MAIL_FROM
 Address of the sender. See \fICURLOPT_MAIL_FROM(3)\fP

docs/libcurl/curl_multi_setopt.3

@@ -63,6 +63,8 @@ See \fICURLMOPT_PUSHDATA(3)\fP
 See \fICURLMOPT_SOCKETFUNCTION(3)\fP
 .IP CURLMOPT_SOCKETDATA
 See \fICURLMOPT_SOCKETDATA(3)\fP
+.IP CURLMOPT_STREAM_WINDOW_SIZE
+See \fICURLMOPT_STREAM_WINDOW_SIZE(3)\fP
 .IP CURLMOPT_TIMERFUNCTION
 See \fICURLMOPT_TIMERFUNCTION(3)\fP
 .IP CURLMOPT_TIMERDATA

docs/libcurl/opts/CURLMOPT_STREAM_WINDOW_SIZE.3

@@ -0,0 +1,60 @@
+.\" **************************************************************************
+.\" *                                  _   _ ____  _
+.\" *  Project                     ___| | | |  _ \| |
+.\" *                             / __| | | | |_) | |
+.\" *                            | (__| |_| |  _ <| |___
+.\" *                             \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2021, Daniel Stenberg, <[email protected]>, 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.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 CURLMOPT_STREAM_WINDOW_SIZE 3 "17 Nov 2021" "libcurl 7.81.0" "curl_multi_setopt options"
+.SH NAME
+CURLMOPT_STREAM_WINDOW_SIZE \- set stream window size for http2
+.SH SYNOPSIS
+.nf
+#include <curl/curl.h>
+
+CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_STREAM_WINDOW_SIZE,
+                            long size);
+.fi
+.SH DESCRIPTION
+Pass a long indicating the sender's HTTP/2 initial stream window \fBsize\fP in
+bytes. This setting affects the initial window size of all streams. When using
+\fIcurl_easy_pause(3)\fP , this value is also the maximum number of bytes libcurl
+has to buffer for a paused stream.
+
+This option is for the multi handle's use only. When using the easy interface,
+you should instead use the \fICURLOPT_STREAM_WINDOW_SIZE(3)\fP option.
+
+Valid values range from 1 to 2147483647 (0x7FFFFFFF).
+.SH DEFAULT
+33554432 (32 megabytes)
+.SH PROTOCOLS
+HTTP/2
+.SH EXAMPLE
+.nf
+  CURLM *m = curl_multi_init();
+  /* set stream window size to HTTP/2 default 2^16-1 */
+  curl_multi_setopt(m, CURLMOPT_STREAM_WINDOW_SIZE, 65535L);
+.fi
+.SH AVAILABILITY
+Added in 7.81.0
+.SH RETURN VALUE
+Returns CURLM_OK of the option is supported and window size is within range,
+CURLM_BAD_FUNCTION_ARGUMENT if not within range. Returns CURLM_UNKNOWN_OPTION
+if the option is not supported.
+.SH "SEE ALSO"
+.BR curl_easy_pause "(3), " CURLOPT_STREAM_WINDOW_SIZE "(3)"

docs/libcurl/opts/CURLOPT_STREAM_WINDOW_SIZE.3

@@ -0,0 +1,62 @@
+.\" **************************************************************************
+.\" *                                  _   _ ____  _
+.\" *  Project                     ___| | | |  _ \| |
+.\" *                             / __| | | | |_) | |
+.\" *                            | (__| |_| |  _ <| |___
+.\" *                             \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2021, Daniel Stenberg, <[email protected]>, 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.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_STREAM_WINDOW_SIZE 3 "17 Nov 2021" "libcurl 7.81.0" "curl_easy_setopt options"
+.SH NAME
+CURLOPT_STREAM_WINDOW_SIZE \- set stream window size for http2
+.SH SYNOPSIS
+.nf
+#include <curl/curl.h>
+
+CURLMcode curl_easy_setopt(CURL *handle, CURLOPT_STREAM_WINDOW_SIZE,
+                           long size);
+.fi
+.SH DESCRIPTION
+Pass a long indicating the sender's HTTP/2 initial stream window \fBsize\fP in
+bytes. This setting affects the initial window size of all streams. When using
+\fIcurl_easy_pause(3)\fP , this value is also the maximum number of bytes libcurl
+has to buffer for a paused stream.
+
+If you add this easy handle to a multi handle, this setting is not
+acknowledged, and you must instead use \fIcurl_multi_setopt(3)\fP and the
+\fICURLMOPT_STREAM_WINDOW_SIZE(3)\fP option.
+
+Valid values range from 1 to 2147483647 (0x7FFFFFFF).
+.SH DEFAULT
+33554432 (32 megabytes)
+.SH PROTOCOLS
+HTTP/2
+.SH EXAMPLE
+.nf
+  CURL *curl = curl_easy_init();
+  /* set stream window size to HTTP/2 default 2^16-1 */
+  curl_easy_setopt(curl, CURLOPT_STREAM_WINDOW_SIZE, 65535L);
+.fi
+.SH AVAILABILITY
+Added in 7.81.0
+.SH RETURN VALUE
+
+Returns CURLE_OK of the option is supported and window size is within range,
+CURLE_BAD_FUNCTION_ARGUMENT if not within range. Returns CURLE_UNKNOWN_OPTION
+if the option is not supported.
+.SH "SEE ALSO"
+.BR curl_easy_pause "(3), " CURLMOPT_STREAM_WINDOW_SIZE "(3)"

docs/libcurl/opts/Makefile.inc

@@ -103,6 +103,7 @@ man_MANS =                                      \
   CURLMOPT_PUSHFUNCTION.3                       \
   CURLMOPT_SOCKETDATA.3                         \
   CURLMOPT_SOCKETFUNCTION.3                     \
+  CURLMOPT_STREAM_WINDOW_SIZE.3                 \
   CURLMOPT_TIMERDATA.3                          \
   CURLMOPT_TIMERFUNCTION.3                      \
   CURLOPT_ABSTRACT_UNIX_SOCKET.3                \
@@ -361,6 +362,7 @@ man_MANS =                                      \
   CURLOPT_STREAM_DEPENDS.3                      \
   CURLOPT_STREAM_DEPENDS_E.3                    \
   CURLOPT_STREAM_WEIGHT.3                       \
+  CURLOPT_STREAM_WINDOW_SIZE.3                  \
   CURLOPT_SUPPRESS_CONNECT_HEADERS.3            \
   CURLOPT_TCP_FASTOPEN.3                        \
   CURLOPT_TCP_KEEPALIVE.3                       \

docs/libcurl/symbols-in-versions

@@ -339,6 +339,7 @@ CURLMOPT_PUSHDATA               7.44.0
 CURLMOPT_PUSHFUNCTION           7.44.0
 CURLMOPT_SOCKETDATA             7.15.4
 CURLMOPT_SOCKETFUNCTION         7.15.4
+CURLMOPT_STREAM_WINDOW_SIZE     7.81.0
 CURLMOPT_TIMERDATA              7.16.0
 CURLMOPT_TIMERFUNCTION          7.16.0
 CURLMSG_DONE                    7.9.6
@@ -651,6 +652,7 @@ CURLOPT_STDERR                  7.1
 CURLOPT_STREAM_DEPENDS          7.46.0
 CURLOPT_STREAM_DEPENDS_E        7.46.0
 CURLOPT_STREAM_WEIGHT           7.46.0
+CURLOPT_STREAM_WINDOW_SIZE      7.81.0
 CURLOPT_SUPPRESS_CONNECT_HEADERS 7.54.0
 CURLOPT_TCP_FASTOPEN            7.49.0
 CURLOPT_TCP_KEEPALIVE           7.25.0

include/curl/curl.h

@@ -2135,6 +2135,9 @@ typedef enum {
   /* Set MIME option flags. */
   CURLOPT(CURLOPT_MIME_OPTIONS, CURLOPTTYPE_LONG, 315),
 
+  /* Stream window size */
+  CURLOPT(CURLOPT_STREAM_WINDOW_SIZE, CURLOPTTYPE_LONG, 316),
+
   CURLOPT_LASTENTRY /* the last unused */
 } CURLoption;
 

include/curl/multi.h

@@ -395,6 +395,9 @@ typedef enum {
   /* maximum number of concurrent streams to support on a connection */
   CURLOPT(CURLMOPT_MAX_CONCURRENT_STREAMS, CURLOPTTYPE_LONG, 16),
 
+  /* stream window size (default 32M) */
+  CURLOPT(CURLMOPT_STREAM_WINDOW_SIZE, CURLOPTTYPE_LONG, 17),
+
   CURLMOPT_LASTENTRY /* the last unused */
 } CURLMoption;
 

lib/easy.c

@@ -681,6 +681,10 @@ static CURLcode easy_perform(struct Curl_easy *data, bool events)
   /* Copy the MAXCONNECTS option to the multi handle */
   curl_multi_setopt(multi, CURLMOPT_MAXCONNECTS, data->set.maxconnects);
 
+  /* Copy the STREAM_WINDOW_SIZE option to the multi handle */
+  curl_multi_setopt(multi, CURLMOPT_STREAM_WINDOW_SIZE,
+    data->set.stream_window_size);
+
   mcode = curl_multi_add_handle(multi, data);
   if(mcode) {
     curl_multi_cleanup(multi);

lib/easyoptions.c

@@ -309,6 +309,7 @@ struct curl_easyoption Curl_easyopts[] = {
   {"STREAM_DEPENDS", CURLOPT_STREAM_DEPENDS, CURLOT_OBJECT, 0},
   {"STREAM_DEPENDS_E", CURLOPT_STREAM_DEPENDS_E, CURLOT_OBJECT, 0},
   {"STREAM_WEIGHT", CURLOPT_STREAM_WEIGHT, CURLOT_LONG, 0},
+  {"STREAM_WINDOW_SIZE", CURLOPT_STREAM_WINDOW_SIZE, CURLOT_LONG, 0},
   {"SUPPRESS_CONNECT_HEADERS", CURLOPT_SUPPRESS_CONNECT_HEADERS,
    CURLOT_LONG, 0},
   {"TCP_FASTOPEN", CURLOPT_TCP_FASTOPEN, CURLOT_LONG, 0},
@@ -360,6 +361,6 @@ struct curl_easyoption Curl_easyopts[] = {
  */
 int Curl_easyopts_check(void)
 {
-  return ((CURLOPT_LASTENTRY%10000) != (315 + 1));
+  return ((CURLOPT_LASTENTRY%10000) != (316 + 1));
 }
 #endif

lib/http2.c

@@ -56,8 +56,6 @@
 #define NGHTTP2_HAS_SET_LOCAL_WINDOW_SIZE 1
 #endif
 
-#define HTTP2_HUGE_WINDOW_SIZE (32 * 1024 * 1024) /* 32 MB */
-
 #ifdef DEBUG_HTTP2
 #define H2BUGF(x) x
 #else
@@ -1194,7 +1192,7 @@ static void populate_settings(struct Curl_easy *data,
   iv[0].value = Curl_multi_max_concurrent_streams(data->multi);
 
   iv[1].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
-  iv[1].value = HTTP2_HUGE_WINDOW_SIZE;
+  iv[1].value = data->multi->stream_window_size;
 
   iv[2].settings_id = NGHTTP2_SETTINGS_ENABLE_PUSH;
   iv[2].value = data->multi->push_cb != NULL;
@@ -2375,7 +2373,7 @@ CURLcode Curl_http2_stream_pause(struct Curl_easy *data, bool pause)
   else {
     struct HTTP *stream = data->req.p.http;
     struct http_conn *httpc = &data->conn->proto.httpc;
-    uint32_t window = !pause * HTTP2_HUGE_WINDOW_SIZE;
+    uint32_t window = !pause * data->multi->stream_window_size;
     int rv = nghttp2_session_set_local_window_size(httpc->h2,
                                                    NGHTTP2_FLAG_NONE,
                                                    stream->stream_id,

lib/http2.h

@@ -31,6 +31,8 @@
    from the peer */
 #define DEFAULT_MAX_CONCURRENT_STREAMS 100
 
+#define HTTP2_HUGE_WINDOW_SIZE (32 * 1024 * 1024) /* 32 MB */
+
 /*
  * Store nghttp2 version info in this buffer.
  */

lib/multi.c

@@ -379,6 +379,9 @@ struct Curl_multi *Curl_multi_handle(int hashsize, /* socket hash */
   /* -1 means it not set by user, use the default value */
   multi->maxconnects = -1;
   multi->max_concurrent_streams = 100;
+#ifdef USE_NGHTTP2
+  multi->stream_window_size = HTTP2_HUGE_WINDOW_SIZE;
+#endif
   multi->ipv6_works = Curl_ipv6works(NULL);
 
 #ifdef USE_WINSOCK
@@ -3154,6 +3157,16 @@ CURLMcode curl_multi_setopt(struct Curl_multi *multi,
       multi->max_concurrent_streams = curlx_sltoui(streams);
     }
     break;
+  case CURLMOPT_STREAM_WINDOW_SIZE:
+    {
+      long stream_window_size = va_arg(param, long);
+      if((stream_window_size > 0) &&
+         ((unsigned long)stream_window_size <= 0x7FFFFFFF))
+        multi->stream_window_size = curlx_sltoui(stream_window_size);
+      else
+        return CURLM_BAD_FUNCTION_ARGUMENT;
+    }
+    break;
   default:
     res = CURLM_UNKNOWN_OPTION;
     break;

lib/multihandle.h

@@ -139,6 +139,7 @@ struct Curl_multi {
   struct curltime timer_lastcall; /* the fixed time for the timeout for the
                                     previous callback */
   unsigned int max_concurrent_streams;
+  unsigned int stream_window_size;
 
 #ifdef USE_WINSOCK
   WSAEVENT wsa_event; /* winsock event used for waits */

lib/setopt.c

@@ -3036,6 +3036,16 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
   case CURLOPT_PREREQDATA:
     data->set.prereq_userp = va_arg(param, void *);
     break;
+  case CURLOPT_STREAM_WINDOW_SIZE:
+    {
+      long stream_window_size = va_arg(param, long);
+      if((stream_window_size > 0) &&
+         ((unsigned long)stream_window_size <= 0x7FFFFFFF))
+        data->set.stream_window_size = curlx_sltoui(stream_window_size);
+      else
+        return CURLE_BAD_FUNCTION_ARGUMENT;
+    }
+    break;
   default:
     /* unknown tag and its companion, just ignore: */
     result = CURLE_UNKNOWN_OPTION;

lib/url.c

@@ -619,6 +619,9 @@ CURLcode Curl_init_userdefined(struct Curl_easy *data)
   set->fnmatch = ZERO_NULL;
   set->upkeep_interval_ms = CURL_UPKEEP_INTERVAL_DEFAULT;
   set->maxconnects = DEFAULT_CONNCACHE_SIZE; /* for easy handles */
+#ifdef USE_NGHTTP2
+  set->stream_window_size = HTTP2_HUGE_WINDOW_SIZE; /* for easy handles */
+#endif
   set->maxage_conn = 118;
   set->maxlifetime_conn = 0;
   set->http09_allowed = FALSE;

lib/urldata.h

@@ -1775,6 +1775,7 @@ struct UserDefined {
   struct Curl_easy *stream_depends_on;
   int stream_weight;
   struct Curl_http2_dep *stream_dependents;
+  unsigned int stream_window_size;
 
   curl_resolver_start_callback resolver_start; /* optional callback called
                                                   before resolver start */