Structured Overlay support for TTL limited messages:

When the [overlay] configuration key "expire" is set to 1, proposals
and validations will include a hops field. The hops is incremented with
each relay. Messages with a hop count will be dropped when they exceed
the TTL (Time to Live). Messages containing a hops field will not be
relayed or broadcast to older versions of rippled that don't understand
the field.

This change will not affect normal operation of the network or rippled
instances that do not set "expire" to 1.

src/ripple/app/consensus/LedgerConsensus.cpp

@@ -988,9 +988,7 @@ private:
             protocol::TMValidation val;
             val.set_validation (&validation[0], validation.size ());
             // Send signed validation to all of our directly connected peers
-            getApp ().overlay ().foreach (send_always (
+            getApp().overlay().send(val);
-                std::make_shared <Message> (
-                    val, protocol::mtVALIDATION)));
             WriteLog (lsINFO, LedgerConsensus)
                 << "CNF Val " << newLCLHash;
         }
@@ -1256,9 +1254,7 @@ private:
         Blob sig = mOurPosition->sign ();
         prop.set_nodepubkey (&pubKey[0], pubKey.size ());
         prop.set_signature (&sig[0], sig.size ());
-        getApp ().overlay ().foreach (send_always (
+        getApp().overlay().send(prop);
-            std::make_shared<Message> (
-                prop, protocol::mtPROPOSE_LEDGER)));
     }
 
     /** Let peers know that we a particular transactions set so they
@@ -1681,11 +1677,6 @@ private:
         Blob validation = v->getSigned ();
         protocol::TMValidation val;
         val.set_validation (&validation[0], validation.size ());
-    #if 0
-        getApp ().overlay ().visit (RelayMessage (
-            std::make_shared <Message> (
-                val, protocol::mtVALIDATION)));
-    #endif
         getApp().getOPs ().setLastValidation (v);
         WriteLog (lsWARNING, LedgerConsensus) << "Sending partial validation";
     }

src/ripple/app/misc/NetworkOPs.cpp

@@ -1710,21 +1710,10 @@ void NetworkOPsImp::processTrustedProposal (
         }
 
         if (relay)
-        {
+            getApp().overlay().relay(*set,
-            std::set<Peer::id_t> peers;
+                proposal->getSuppressionID());
-            if (getApp().getHashRouter ().swapSet (
-                proposal->getSuppressionID (), peers, SF_RELAYED))
-            {
-                getApp ().overlay ().foreach (send_if_not (
-                    std::make_shared<Message> (
-                        *set, protocol::mtPROPOSE_LEDGER),
-                    peer_in_set(peers)));
-            }
-        }
         else
-        {
             m_journal.info << "Not relaying trusted proposal";
-        }
     }
 }
 

src/ripple/basics/BasicConfig.h

@@ -23,6 +23,7 @@
 #include <beast/container/const_container.h>
 #include <beast/utility/ci_char_traits.h>
 #include <boost/lexical_cast.hpp>
+#include <boost/optional.hpp>
 #include <map>
 #include <ostream>
 #include <string>
@@ -139,6 +140,16 @@ public:
     std::pair <std::string, bool>
     find (std::string const& name) const;
 
+    template <class T>
+    boost::optional<T>
+    get (std::string const& name) const
+    {
+        auto const iter = cont().find(name);
+        if (iter == cont().end())
+            return boost::none;
+        return boost::lexical_cast<T>(iter->second);
+    }
+
     friend
     std::ostream&
     operator<< (std::ostream&, Section const& section);

src/ripple/overlay/Overlay.h

@@ -31,6 +31,7 @@
 #include <beast/cxx14/type_traits.h> // <type_traits>
 #include <boost/asio/buffer.hpp>
 #include <boost/asio/ip/tcp.hpp>
+#include <boost/optional.hpp>
 
 namespace boost { namespace asio { namespace ssl { class context; } } }
 
@@ -65,6 +66,7 @@ public:
         bool auto_connect = true;
         Promote promote = Promote::automatic;
         std::shared_ptr<boost::asio::ssl::context> context;
+        bool expire = false;
     };
 
     typedef std::vector <Peer::ptr> PeerSequence;
@@ -131,6 +133,28 @@ public:
     Peer::ptr
     findPeerByShortID (Peer::id_t const& id) = 0;
 
+    /** Broadcast a proposal. */
+    virtual
+    void
+    send (protocol::TMProposeSet& m) = 0;
+
+    /** Broadcast a validation. */
+    virtual
+    void
+    send (protocol::TMValidation& m) = 0;
+
+    /** Relay a proposal. */
+    virtual
+    void
+    relay (protocol::TMProposeSet& m,
+        uint256 const& uid) = 0;
+
+    /** Relay a validation. */
+    virtual
+    void
+    relay (protocol::TMValidation& m,
+        uint256 const& uid) = 0;
+
     /** Visit every active peer and return a value
         The functor must:
         - Be callable as:

src/ripple/overlay/impl/OverlayImpl.cpp

@@ -18,6 +18,7 @@
 //==============================================================================
 
 #include <BeastConfig.h>
+#include <ripple/app/misc/IHashRouter.h>
 #include <ripple/basics/Log.h>
 #include <ripple/basics/make_SSLContext.h>
 #include <ripple/protocol/JsonFields.h>
@@ -693,6 +694,75 @@ OverlayImpl::findPeerByShortID (Peer::id_t const& id)
     return Peer::ptr();
 }
 
+void
+OverlayImpl::send (protocol::TMProposeSet& m)
+{
+    if (setup_.expire)
+        m.set_hops(0);
+    auto const sm = std::make_shared<Message>(
+        m, protocol::mtPROPOSE_LEDGER);
+    for_each([&](std::shared_ptr<PeerImp> const& p)
+    {
+        if (! m.has_hops() || p->hopsAware())
+            p->send(sm);
+    });
+}
+void
+OverlayImpl::send (protocol::TMValidation& m)
+{
+    if (setup_.expire)
+        m.set_hops(0);
+    auto const sm = std::make_shared<Message>(
+        m, protocol::mtVALIDATION);
+    for_each([&](std::shared_ptr<PeerImp> const& p)
+    {
+        if (! m.has_hops() || p->hopsAware())
+            p->send(sm);
+    });
+}
+
+void
+OverlayImpl::relay (protocol::TMProposeSet& m,
+    uint256 const& uid)
+{
+    if (m.has_hops() && m.hops() >= maxTTL)
+        return;
+    std::set<Peer::id_t> skip;
+    if (! getApp().getHashRouter().swapSet (
+            uid, skip, SF_RELAYED))
+        return;
+    auto const sm = std::make_shared<Message>(
+        m, protocol::mtPROPOSE_LEDGER);
+    for_each([&](std::shared_ptr<PeerImp> const& p)
+    {
+        if (skip.find(p->id()) != skip.end())
+            return;
+        if (! m.has_hops() || p->hopsAware())
+            p->send(sm);
+    });
+}
+
+void
+OverlayImpl::relay (protocol::TMValidation& m,
+    uint256 const& uid)
+{
+    if (m.has_hops() && m.hops() >= maxTTL)
+        return;
+    std::set<Peer::id_t> skip;
+    if (! getApp().getHashRouter().swapSet (
+            uid, skip, SF_RELAYED))
+        return;
+    auto const sm = std::make_shared<Message>(
+        m, protocol::mtVALIDATION);
+    for_each([&](std::shared_ptr<PeerImp> const& p)
+    {
+        if (skip.find(p->id()) != skip.end())
+            return;
+        if (! m.has_hops() || p->hopsAware())
+            p->send(sm);
+    });
+}
+
 //------------------------------------------------------------------------------
 
 void
@@ -777,6 +847,7 @@ setup_Overlay (BasicConfig const& config)
     else
         setup.promote = Overlay::Promote::automatic;
     setup.context = make_SSLContext();
+    setup.expire = get<bool>(section, "expire", false);
     return setup;
 }
 

src/ripple/overlay/impl/OverlayImpl.h

@@ -46,6 +46,11 @@ namespace ripple {
 class PeerImp;
 class BasicConfig;
 
+enum
+{
+    maxTTL = 2
+};
+
 class OverlayImpl : public Overlay
 {
 public:
@@ -174,6 +179,20 @@ public:
     Peer::ptr
     findPeerByShortID (Peer::id_t const& id) override;
 
+    void
+    send (protocol::TMProposeSet& m) override;
+
+    void
+    send (protocol::TMValidation& m) override;
+
+    void
+    relay (protocol::TMProposeSet& m,
+        uint256 const& uid) override;
+
+    void
+    relay (protocol::TMValidation& m,
+        uint256 const& uid) override;
+
     //--------------------------------------------------------------------------
     //
     // OverlayImpl

src/ripple/overlay/impl/PeerImp.cpp

@@ -36,8 +36,10 @@
 #include <ripple/server/ServerHandler.h>
 #include <ripple/protocol/BuildInfo.h>
 #include <ripple/protocol/JsonFields.h>
+#include <beast/module/core/diagnostic/SemanticVersion.h>
 #include <beast/streams/debug_ostream.h>
 #include <beast/weak_fn.h>
+#include <boost/algorithm/string/predicate.hpp>
 #include <boost/asio/io_service.hpp>
 #include <functional>
 #include <beast/cxx14/memory.h> // <memory>
@@ -100,6 +102,20 @@ PeerImp::run()
     if(! strand_.running_in_this_thread())
         return strand_.post(std::bind (
             &PeerImp::run, shared_from_this()));
+    {
+        auto s = getVersion();
+        if (boost::starts_with(s, "rippled-"))
+        {
+            s.erase(s.begin(), s.begin() + 8);
+            beast::SemanticVersion v;
+            if (v.parse(s))
+            {
+                beast::SemanticVersion av;
+                av.parse("0.28.0-rc3");
+                hopsAware_ = v >= av;
+            }
+        }
+    }
     if (m_inbound)
     {
         doAccept();
@@ -1008,6 +1024,10 @@ PeerImp::onMessage (std::shared_ptr <protocol::TMProposeSet> const& m)
 {
     protocol::TMProposeSet& set = *m;
 
+    if (overlay_.setup().expire &&
+            set.has_hops() && ! slot_->cluster())
+        set.set_hops(set.hops() + 1);
+
     // VFALCO Magic numbers are bad
     if ((set.closetime() + 180) < getApp().getOPs().getCloseTimeNC())
         return;
@@ -1276,6 +1296,10 @@ PeerImp::onMessage (std::shared_ptr <protocol::TMValidation> const& m)
     error_code ec;
     std::uint32_t closeTime = getApp().getOPs().getCloseTimeNC();
 
+    if (overlay_.setup().expire &&
+            m->has_hops() && ! slot_->cluster())
+        m->set_hops(m->hops() + 1);
+
     if (m->validation ().size () < 50)
     {
         p_journal_.warning << "Validation: Too small";
@@ -1651,15 +1675,7 @@ PeerImp::checkPropose (Job& job,
         // relay untrusted proposal
         p_journal_.trace <<
             "relaying UNTRUSTED proposal";
-        std::set<Peer::id_t> peers;
+        overlay_.relay(set, proposal->getSuppressionID());
-
-        if (getApp().getHashRouter ().swapSet (
-            proposal->getSuppressionID (), peers, SF_RELAYED))
-        {
-            overlay_.foreach (send_if_not (
-                std::make_shared<Message> (set, protocol::mtPROPOSE_LEDGER),
-                peer_in_set(peers)));
-        }
     }
     else
     {
@@ -1688,15 +1704,9 @@ PeerImp::checkValidation (Job&, STValidation::pointer val,
         validatorsConnection_->onValidation(*val);
     #endif
 
-        std::set<Peer::id_t> peers;
+        if (getApp().getOPs ().recvValidation(
-        if (getApp().getOPs ().recvValidation (val, std::to_string(id())) &&
+                val, std::to_string(id())))
-                getApp().getHashRouter ().swapSet (
+            overlay_.relay(*packet, signingHash);
-                    signingHash, peers, SF_RELAYED))
-        {
-            overlay_.foreach (send_if_not (
-                std::make_shared<Message> (*packet, protocol::mtVALIDATION),
-                peer_in_set(peers)));
-        }
     }
     catch (...)
     {

src/ripple/overlay/impl/PeerImp.h

@@ -153,6 +153,7 @@ private:
     bool gracefulClose_ = false;
     std::unique_ptr <LoadEvent> load_event_;
     std::unique_ptr<Validators::Connection> validatorsConnection_;
+    bool hopsAware_ = false;
 
     //--------------------------------------------------------------------------
 
@@ -237,6 +238,12 @@ public:
         return slot_->cluster();
     }
 
+    bool
+    hopsAware() const
+    {
+        return hopsAware_;
+    }
+
     void
     check();
 

src/ripple/proto/ripple.proto

@@ -173,6 +173,7 @@ message TMProposeSet
     optional bool checkedSignature      = 7;    // node vouches signature is correct
     repeated bytes addedTransactions    = 10;   // not required if number is large
     repeated bytes removedTransactions  = 11;   // not required if number is large
+    optional uint32 hops                = 12;   // Number of hops traveled
 }
 
 enum TxSetStatus
@@ -192,8 +193,9 @@ message TMHaveTransactionSet
 // Used to sign a final closed ledger after reprocessing
 message TMValidation
 {
-    required bytes validation       = 1;        // in STValidation signed form
+    required bytes validation       = 1;    // in STValidation signed form
-    optional bool checkedSignature  = 2;        // node vouches signature is correct
+    optional bool checkedSignature  = 2;    // node vouches signature is correct
+    optional uint32 hops            = 3;    // Number of hops traveled
 }
 
 message TMGetPeers