CURLMOPT_MAX_CONCURRENT_STREAMS: new setopt

Closes #4410

10 files changed, 97 insertions, 6 deletions

diff --git a/docs/libcurl/curl_multi_setopt.3 b/docs/libcurl/curl_multi_setopt.3
index d27c52441..88809d62b 100644
--- a/docs/libcurl/curl_multi_setopt.3
+++ b/docs/libcurl/curl_multi_setopt.3
@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2019, 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
@@ -67,6 +67,8 @@ See \fICURLMOPT_SOCKETDATA(3)\fP
 See \fICURLMOPT_TIMERFUNCTION(3)\fP
 .IP CURLMOPT_TIMERDATA
 See \fICURLMOPT_TIMERDATA(3)\fP
+.IP CURLMOPT_MAX_CONCURRENT_STREAMS
+See \fICURLMOPT_MAX_CONCURRENT_STREAMS(3)\fP
 .SH RETURNS
 The standard CURLMcode for multi interface error codes. Note that it returns a
 CURLM_UNKNOWN_OPTION if you try setting an option that this version of libcurl
diff --git a/docs/libcurl/opts/CURLMOPT_MAX_CONCURRENT_STREAMS.3 b/docs/libcurl/opts/CURLMOPT_MAX_CONCURRENT_STREAMS.3
new file mode 100644
index 000000000..ab044f754
--- /dev/null
+++ b/docs/libcurl/opts/CURLMOPT_MAX_CONCURRENT_STREAMS.3
@@ -0,0 +1,56 @@
+.\" **************************************************************************
+.\" *                                  _   _ ____  _
+.\" *  Project                     ___| | | |  _ \| |
+.\" *                             / __| | | | |_) | |
+.\" *                            | (__| |_| |  _ <| |___
+.\" *                             \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2019, 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 CURLMOPT_MAX_CONCURRENT_STREAMS 3 "06 Nov 2019" "libcurl 7.67.0" "curl_multi_setopt options"
+.SH NAME
+CURLMOPT_MAX_CONCURRENT_STREAMS \- set max concurrent streams for http2
+.SH SYNOPSIS
+.nf
+#include <curl/curl.h>
+
+CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_MAX_CONCURRENT_STREAMS,
+                            long max);
+.fi
+.SH DESCRIPTION
+Pass a long indicating the \fBmax\fP. The set number will be used as the
+maximum number of concurrent streams for a connections that libcurl should
+support on connections done using HTTP/2.
+
+Valid values range from 1 to 2147483647 (2^31 - 1) and defaults to 100.  The
+value passed here would be honoured based on other system resources
+properties.
+.SH DEFAULT
+100
+.SH PROTOCOLS
+All
+.SH EXAMPLE
+.nf
+  CURLM *m = curl_multi_init();
+  /* max concurrent streams 200 */
+  curl_multi_setopt(m, CURLMOPT_MAX_CONCURRENT_STREAMS, 200L);
+.fi
+.SH AVAILABILITY
+Added in 7.67.0
+.SH RETURN VALUE
+Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not.
+.SH "SEE ALSO"
+.BR CURLOPT_MAXCONNECTS "(3), " CURLMOPT_MAXCONNECTS.3 "(3), "
diff --git a/docs/libcurl/opts/Makefile.inc b/docs/libcurl/opts/Makefile.inc
index b5f62a159..93c4357d2 100644
--- a/docs/libcurl/opts/Makefile.inc
+++ b/docs/libcurl/opts/Makefile.inc
@@ -68,6 +68,7 @@ man_MANS =                                      \
   CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE.3          \
   CURLMOPT_CONTENT_LENGTH_PENALTY_SIZE.3        \
   CURLMOPT_MAXCONNECTS.3                        \
+  CURLMOPT_MAX_CONCURRENT_STREAMS.3             \
   CURLMOPT_MAX_HOST_CONNECTIONS.3               \
   CURLMOPT_MAX_PIPELINE_LENGTH.3                \
   CURLMOPT_MAX_TOTAL_CONNECTIONS.3              \
@@ -97,7 +98,6 @@ man_MANS =                                      \
   CURLOPT_CHUNK_END_FUNCTION.3                  \
   CURLOPT_CLOSESOCKETDATA.3                     \
   CURLOPT_CLOSESOCKETFUNCTION.3                 \
-  CURLOPT_UPKEEP_INTERVAL_MS.3             \
   CURLOPT_CONNECTTIMEOUT.3                      \
   CURLOPT_CONNECTTIMEOUT_MS.3                   \
   CURLOPT_CONNECT_ONLY.3                        \
@@ -113,8 +113,8 @@ man_MANS =                                      \
   CURLOPT_COPYPOSTFIELDS.3                      \
   CURLOPT_CRLF.3                                \
   CURLOPT_CRLFILE.3                             \
-  CURLOPT_CUSTOMREQUEST.3                       \
   CURLOPT_CURLU.3                               \
+  CURLOPT_CUSTOMREQUEST.3                       \
   CURLOPT_DEBUGDATA.3                           \
   CURLOPT_DEBUGFUNCTION.3                       \
   CURLOPT_DEFAULT_PROTOCOL.3                    \
@@ -168,8 +168,6 @@ man_MANS =                                      \
   CURLOPT_HTTP_TRANSFER_DECODING.3              \
   CURLOPT_HTTP_VERSION.3                        \
   CURLOPT_IGNORE_CONTENT_LENGTH.3               \
-  CURLOPT_TRAILERDATA.3                         \
-  CURLOPT_TRAILERFUNCTION.3                     \
   CURLOPT_INFILESIZE.3                          \
   CURLOPT_INFILESIZE_LARGE.3                    \
   CURLOPT_INTERFACE.3                           \
@@ -332,10 +330,13 @@ man_MANS =                                      \
   CURLOPT_TLSAUTH_PASSWORD.3                    \
   CURLOPT_TLSAUTH_TYPE.3                        \
   CURLOPT_TLSAUTH_USERNAME.3                    \
+  CURLOPT_TRAILERDATA.3                         \
+  CURLOPT_TRAILERFUNCTION.3                     \
   CURLOPT_TRANSFERTEXT.3                        \
   CURLOPT_TRANSFER_ENCODING.3                   \
   CURLOPT_UNIX_SOCKET_PATH.3                    \
   CURLOPT_UNRESTRICTED_AUTH.3                   \
+  CURLOPT_UPKEEP_INTERVAL_MS.3                  \
   CURLOPT_UPLOAD.3                              \
   CURLOPT_UPLOAD_BUFFERSIZE.3                   \
   CURLOPT_URL.3                                 \
diff --git a/docs/libcurl/symbols-in-versions b/docs/libcurl/symbols-in-versions
index ff0dfb238..3e144a719 100644
--- a/docs/libcurl/symbols-in-versions
+++ b/docs/libcurl/symbols-in-versions
@@ -319,6 +319,7 @@ CURLMOPT_MAXCONNECTS            7.16.3
 CURLMOPT_MAX_HOST_CONNECTIONS   7.30.0
 CURLMOPT_MAX_PIPELINE_LENGTH    7.30.0
 CURLMOPT_MAX_TOTAL_CONNECTIONS  7.30.0
+CURLMOPT_MAX_CONCURRENT_STREAMS  7.67.0
 CURLMOPT_PIPELINING             7.16.0
 CURLMOPT_PIPELINING_SERVER_BL   7.30.0
 CURLMOPT_PIPELINING_SITE_BL     7.30.0
diff --git a/include/curl/multi.h b/include/curl/multi.h
index 02df0f389..b39218395 100644
--- a/include/curl/multi.h
+++ b/include/curl/multi.h
@@ -396,6 +396,9 @@ typedef enum {
   /* This is the argument passed to the server push callback */
   CINIT(PUSHDATA, OBJECTPOINT, 15),
 
+  /* maximum number of concurrent streams to support on a connection */
+  CINIT(MAX_CONCURRENT_STREAMS, LONG, 16),
+
   CURLMOPT_LASTENTRY /* the last unused */
 } CURLMoption;
 
@@ -448,6 +451,9 @@ typedef int (*curl_push_callback)(CURL *parent,
                                   struct curl_pushheaders *headers,
                                   void *userp);
 
+/* value for MAXIMUM CONCURRENT STREAMS upper limit */
+#define INITIAL_MAX_CONCURRENT_STREAMS ((1U << 31) - 1)
+
 #ifdef __cplusplus
 } /* end of extern "C" */
 #endif
diff --git a/lib/http2.c b/lib/http2.c
index 98ea90358..d2f5da17a 100644
--- a/lib/http2.c
+++ b/lib/http2.c
@@ -1159,7 +1159,7 @@ static void populate_settings(struct connectdata *conn,
   nghttp2_settings_entry *iv = httpc->local_settings;
 
   iv[0].settings_id = NGHTTP2_SETTINGS_MAX_CONCURRENT_STREAMS;
-  iv[0].value = 100;
+  iv[0].value = (uint32_t)Curl_multi_max_concurrent_streams(conn->data->multi);
 
   iv[1].settings_id = NGHTTP2_SETTINGS_INITIAL_WINDOW_SIZE;
   iv[1].value = HTTP2_HUGE_WINDOW_SIZE;
diff --git a/lib/multi.c b/lib/multi.c
index 22e0dcfd1..6dfe8842e 100755
--- a/lib/multi.c
+++ b/lib/multi.c
@@ -2772,6 +2772,16 @@ CURLMcode curl_multi_setopt(struct Curl_multi *multi,
     break;
   case CURLMOPT_PIPELINING_SERVER_BL:
     break;
+  case CURLMOPT_MAX_CONCURRENT_STREAMS:
+    {
+      long streams = va_arg(param, long);
+      if(streams < 1)
+        streams = 100;
+      multi->max_concurrent_streams =
+          (streams > (long)INITIAL_MAX_CONCURRENT_STREAMS)?
+          (long)INITIAL_MAX_CONCURRENT_STREAMS : streams;
+    }
+    break;
   default:
     res = CURLM_UNKNOWN_OPTION;
     break;
@@ -3210,3 +3220,9 @@ void Curl_multi_dump(struct Curl_multi *multi)
   }
 }
 #endif
+
+size_t Curl_multi_max_concurrent_streams(struct Curl_multi *multi)
+{
+  return multi ? ((size_t)multi->max_concurrent_streams ?
+                  (size_t)multi->max_concurrent_streams : 100) : 0;
+}
diff --git a/lib/multihandle.h b/lib/multihandle.h
index 279379ae0..b65bd9638 100644
--- a/lib/multihandle.h
+++ b/lib/multihandle.h
@@ -133,6 +133,7 @@ struct Curl_multi {
   struct curltime timer_lastcall; /* the fixed time for the timeout for the
                                     previous callback */
   bool in_callback;            /* true while executing a callback */
+  long max_concurrent_streams; /* max concurrent streams client to support */
 };
 
 #endif /* HEADER_CURL_MULTIHANDLE_H */
diff --git a/lib/multiif.h b/lib/multiif.h
index 0755a7cd2..75025232c 100644
--- a/lib/multiif.h
+++ b/lib/multiif.h
@@ -89,4 +89,10 @@ CURLMcode Curl_multi_add_perform(struct Curl_multi *multi,
                                  struct Curl_easy *data,
                                  struct connectdata *conn);
 
+
+/* Return the value of the CURLMOPT_MAX_CONCURRENT_STREAMS option
+ * If not specified or 0, default would be 100
+ */
+size_t Curl_multi_max_concurrent_streams(struct Curl_multi *multi);
+
 #endif /* HEADER_CURL_MULTIIF_H */
diff --git a/packages/OS400/curl.inc.in b/packages/OS400/curl.inc.in
index 5a53b1b21..8be6c8986 100644
--- a/packages/OS400/curl.inc.in
+++ b/packages/OS400/curl.inc.in
@@ -1841,6 +1841,8 @@
      d                 c                   20014
      d  CURLMOPT_PUSHDATA...
      d                 c                   10015
+     d  CURLMOPT_MAX_CONCURRENT_STREAMS...
+     d                 c                   10016
       *
       * Bitmask bits for CURLMOPT_PIPELING.
       *