Repository: trafficserver
Updated Branches:
  refs/heads/master 1e9c9484c -> 0e6e5c151


TS-4087: Reduce SETTINGS_MAX_CONCURRENT_STREAMS when too many streams

Add below variables in records.config
- proxy.config.http2.min_concurrent_streams_in
- proxy.config.http2.max_active_streams_in

When connection wide active stream are larger than 
proxy.config.http2.max_active_streams_in,
SETTINGS_MAX_CONCURRENT_STREAMS is reduced to 
proxy.config.http2.min_concurrent_streams_in
in new connections.

If the value of proxy.config.http2.max_active_streams_in is 0, there is no 
limit.

This closes #485


Project: http://git-wip-us.apache.org/repos/asf/trafficserver/repo
Commit: http://git-wip-us.apache.org/repos/asf/trafficserver/commit/0e6e5c15
Tree: http://git-wip-us.apache.org/repos/asf/trafficserver/tree/0e6e5c15
Diff: http://git-wip-us.apache.org/repos/asf/trafficserver/diff/0e6e5c15

Branch: refs/heads/master
Commit: 0e6e5c151cde5f06c15e295f663a98b2b7d37a6d
Parents: 1e9c948
Author: Masaori Koshiba <[email protected]>
Authored: Mon Feb 15 20:57:25 2016 +0900
Committer: Masaori Koshiba <[email protected]>
Committed: Tue Mar 22 10:52:37 2016 +0900

----------------------------------------------------------------------
 mgmt/RecordsConfig.cc               |  4 ++++
 proxy/http2/HTTP2.cc                | 12 ++++++++---
 proxy/http2/HTTP2.h                 |  5 ++++-
 proxy/http2/Http2ConnectionState.cc | 35 ++++++++++++++++++++++++++++++++
 proxy/http2/Http2ConnectionState.h  |  4 +++-
 5 files changed, 55 insertions(+), 5 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/mgmt/RecordsConfig.cc
----------------------------------------------------------------------
diff --git a/mgmt/RecordsConfig.cc b/mgmt/RecordsConfig.cc
index 0e963c9..b0e0e6a 100644
--- a/mgmt/RecordsConfig.cc
+++ b/mgmt/RecordsConfig.cc
@@ -1977,6 +1977,10 @@ static const RecordElement RecordsConfig[] =
   ,
   {RECT_CONFIG, "proxy.config.http2.max_concurrent_streams_in", RECD_INT, 
"100", RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}
   ,
+  {RECT_CONFIG, "proxy.config.http2.min_concurrent_streams_in", RECD_INT, 
"10", RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}
+  ,
+  {RECT_CONFIG, "proxy.config.http2.max_active_streams_in", RECD_INT, "0", 
RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}
+  ,
   {RECT_CONFIG, "proxy.config.http2.initial_window_size_in", RECD_INT, 
"1048576", RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}
   ,
   {RECT_CONFIG, "proxy.config.http2.max_frame_size", RECD_INT, "16384", 
RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/proxy/http2/HTTP2.cc
----------------------------------------------------------------------
diff --git a/proxy/http2/HTTP2.cc b/proxy/http2/HTTP2.cc
index 5cb9d79..c9ea2bc 100644
--- a/proxy/http2/HTTP2.cc
+++ b/proxy/http2/HTTP2.cc
@@ -727,7 +727,10 @@ http2_decode_header_blocks(HTTPHdr *hdr, const uint8_t 
*buf_start, const uint8_t
 }
 
 // Initialize this subsystem with librecords configs (for now)
-uint32_t Http2::max_concurrent_streams = 100;
+uint32_t Http2::max_concurrent_streams_in = 100;
+uint32_t Http2::min_concurrent_streams_in = 10;
+uint32_t Http2::max_active_streams_in = 0;
+bool Http2::throttling = false;
 uint32_t Http2::initial_window_size = 1048576;
 uint32_t Http2::max_frame_size = 16384;
 uint32_t Http2::header_table_size = 4096;
@@ -740,7 +743,9 @@ uint32_t Http2::active_timeout_in = 0;
 void
 Http2::init()
 {
-  REC_EstablishStaticConfigInt32U(max_concurrent_streams, 
"proxy.config.http2.max_concurrent_streams_in");
+  REC_EstablishStaticConfigInt32U(max_concurrent_streams_in, 
"proxy.config.http2.max_concurrent_streams_in");
+  REC_EstablishStaticConfigInt32U(min_concurrent_streams_in, 
"proxy.config.http2.min_concurrent_streams_in");
+  REC_EstablishStaticConfigInt32U(max_active_streams_in, 
"proxy.config.http2.max_active_streams_in");
   REC_EstablishStaticConfigInt32U(initial_window_size, 
"proxy.config.http2.initial_window_size_in");
   REC_EstablishStaticConfigInt32U(max_frame_size, 
"proxy.config.http2.max_frame_size");
   REC_EstablishStaticConfigInt32U(header_table_size, 
"proxy.config.http2.header_table_size");
@@ -751,7 +756,8 @@ Http2::init()
   REC_EstablishStaticConfigInt32U(active_timeout_in, 
"proxy.config.http2.active_timeout_in");
 
   // If any settings is broken, ATS should not start
-  
ink_release_assert(http2_settings_parameter_is_valid({HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS,
 max_concurrent_streams}) &&
+  
ink_release_assert(http2_settings_parameter_is_valid({HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS,
 max_concurrent_streams_in}) &&
+                     
http2_settings_parameter_is_valid({HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, 
min_concurrent_streams_in}) &&
                      
http2_settings_parameter_is_valid({HTTP2_SETTINGS_INITIAL_WINDOW_SIZE, 
initial_window_size}) &&
                      
http2_settings_parameter_is_valid({HTTP2_SETTINGS_MAX_FRAME_SIZE, 
max_frame_size}) &&
                      
http2_settings_parameter_is_valid({HTTP2_SETTINGS_HEADER_TABLE_SIZE, 
header_table_size}) &&

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/proxy/http2/HTTP2.h
----------------------------------------------------------------------
diff --git a/proxy/http2/HTTP2.h b/proxy/http2/HTTP2.h
index 10e22e3..9b62b17 100644
--- a/proxy/http2/HTTP2.h
+++ b/proxy/http2/HTTP2.h
@@ -342,7 +342,10 @@ int64_t http2_write_header_fragment(HTTPHdr *, 
MIMEFieldIter &, uint8_t *, uint6
 class Http2
 {
 public:
-  static uint32_t max_concurrent_streams;
+  static uint32_t max_concurrent_streams_in;
+  static uint32_t min_concurrent_streams_in;
+  static uint32_t max_active_streams_in;
+  static bool throttling;
   static uint32_t initial_window_size;
   static uint32_t max_frame_size;
   static uint32_t header_table_size;

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/proxy/http2/Http2ConnectionState.cc
----------------------------------------------------------------------
diff --git a/proxy/http2/Http2ConnectionState.cc 
b/proxy/http2/Http2ConnectionState.cc
index 077f8ea..5180b3f 100644
--- a/proxy/http2/Http2ConnectionState.cc
+++ b/proxy/http2/Http2ConnectionState.cc
@@ -727,6 +727,8 @@ Http2ConnectionState::main_event_handler(int event, void 
*edata)
     // settings.
     Http2ConnectionSettings configured_settings;
     configured_settings.settings_from_configs();
+    configured_settings.set(HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, 
_adjust_concurrent_stream());
+
     send_settings_frame(configured_settings);
 
     if (server_settings.get(HTTP2_SETTINGS_INITIAL_WINDOW_SIZE) > 
HTTP2_INITIAL_WINDOW_SIZE) {
@@ -1167,3 +1169,36 @@ 
Http2ConnectionState::send_window_update_frame(Http2StreamId id, uint32_t size)
   SCOPED_MUTEX_LOCK(lock, this->ua_session->mutex, this_ethread());
   this->ua_session->handleEvent(HTTP2_SESSION_EVENT_XMIT, &window_update);
 }
+
+// Return min_concurrent_streams_in when current client streams number is 
larger than max_active_streams_in.
+// Main purpose of this is preventing DDoS Attacks.
+unsigned
+Http2ConnectionState::_adjust_concurrent_stream()
+{
+  if (Http2::max_active_streams_in == 0) {
+    // Throttling down is disabled.
+    return Http2::max_concurrent_streams_in;
+  }
+
+  int64_t current_client_streams = 0;
+  RecGetRawStatSum(http2_rsb, HTTP2_STAT_CURRENT_CLIENT_STREAM_COUNT, 
&current_client_streams);
+
+  DebugHttp2Con(ua_session, "current client streams: %" PRId64, 
current_client_streams);
+
+  if (current_client_streams >= Http2::max_active_streams_in) {
+    if (!Http2::throttling) {
+      Warning("too many streams: %" PRId64 ", reduce 
SETTINGS_MAX_CONCURRENT_STREAMS to %d", current_client_streams,
+              Http2::min_concurrent_streams_in);
+      Http2::throttling = true;
+    }
+
+    return Http2::min_concurrent_streams_in;
+  } else {
+    if (Http2::throttling) {
+      Note("revert SETTINGS_MAX_CONCURRENT_STREAMS to %d", 
Http2::max_concurrent_streams_in);
+      Http2::throttling = false;
+    }
+  }
+
+  return Http2::max_concurrent_streams_in;
+}

http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/proxy/http2/Http2ConnectionState.h
----------------------------------------------------------------------
diff --git a/proxy/http2/Http2ConnectionState.h 
b/proxy/http2/Http2ConnectionState.h
index 9423c4e..afd0cf2 100644
--- a/proxy/http2/Http2ConnectionState.h
+++ b/proxy/http2/Http2ConnectionState.h
@@ -51,7 +51,7 @@ public:
   void
   settings_from_configs()
   {
-    settings[indexof(HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS)] = 
Http2::max_concurrent_streams;
+    settings[indexof(HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS)] = 
Http2::max_concurrent_streams_in;
     settings[indexof(HTTP2_SETTINGS_INITIAL_WINDOW_SIZE)] = 
Http2::initial_window_size;
     settings[indexof(HTTP2_SETTINGS_MAX_FRAME_SIZE)] = Http2::max_frame_size;
     settings[indexof(HTTP2_SETTINGS_HEADER_TABLE_SIZE)] = 
Http2::header_table_size;
@@ -199,6 +199,8 @@ private:
   Http2ConnectionState(const Http2ConnectionState &);            // noncopyable
   Http2ConnectionState &operator=(const Http2ConnectionState &); // noncopyable
 
+  unsigned _adjust_concurrent_stream();
+
   // NOTE: 'stream_list' has only active streams.
   //   If given Stream Identifier is not found in stream_list and it is less
   //   than or equal to latest_streamid, the state of Stream

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