Kill insecure_random and associated global state

There are only a few uses of `insecure_random` outside the tests.
This PR replaces uses of insecure_random (and its accompanying global
state) in the core code with an FastRandomContext that is automatically
seeded on creation.

This is meant to be used for inner loops. The FastRandomContext
can be in the outer scope, or the class itself, then rand32() is used
inside the loop. Useful e.g. for pushing addresses in CNode or the fee
rounding, or randomization for coin selection.

As a context is created per purpose, thus it gets rid of
cross-thread unprotected shared usage of a single set of globals, this
should also get rid of the potential race conditions.

- I'd say TxMempool::check is not called enough to warrant using a special
  fast random context, this is switched to GetRand() (open for
  discussion...)

- The use of `insecure_rand` in ConnectThroughProxy has been replaced by
  an atomic integer counter. The only goal here is to have a different
  credentials pair for each connection to go on a different Tor circuit,
  it does not need to be random nor unpredictable.

- To avoid having a FastRandomContext on every CNode, the context is
  passed into PushAddress as appropriate.

There remains an insecure_random for test usage in `test_random.h`.

14 files changed, 41 insertions, 21 deletions

diff --git a/src/test/addrman_tests.cpp b/src/test/addrman_tests.cpp
index 5ccaeb57bb..adff09f754 100644
--- a/src/test/addrman_tests.cpp
+++ b/src/test/addrman_tests.cpp
@@ -26,7 +26,7 @@ public:
     void MakeDeterministic()
     {
         nKey.SetNull();
-        seed_insecure_rand(true);
+        insecure_rand = FastRandomContext(true);
     }
 
     int RandomInt(int nMax)
diff --git a/src/test/coins_tests.cpp b/src/test/coins_tests.cpp
index e692326559..b487686136 100644
--- a/src/test/coins_tests.cpp
+++ b/src/test/coins_tests.cpp
@@ -3,7 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "coins.h"
-#include "random.h"
+#include "test_random.h"
 #include "script/standard.h"
 #include "uint256.h"
 #include "utilstrencodings.h"
diff --git a/src/test/crypto_tests.cpp b/src/test/crypto_tests.cpp
index ff0adae1d2..c7b4fb240c 100644
--- a/src/test/crypto_tests.cpp
+++ b/src/test/crypto_tests.cpp
@@ -9,7 +9,7 @@
 #include "crypto/sha512.h"
 #include "crypto/hmac_sha256.h"
 #include "crypto/hmac_sha512.h"
-#include "random.h"
+#include "test_random.h"
 #include "utilstrencodings.h"
 #include "test/test_bitcoin.h"
 
diff --git a/src/test/merkle_tests.cpp b/src/test/merkle_tests.cpp
index b40ab848dc..66ca381ea7 100644
--- a/src/test/merkle_tests.cpp
+++ b/src/test/merkle_tests.cpp
@@ -4,7 +4,7 @@
 
 #include "consensus/merkle.h"
 #include "test/test_bitcoin.h"
-#include "random.h"
+#include "test_random.h"
 
 #include <boost/test/unit_test.hpp>
 
diff --git a/src/test/net_tests.cpp b/src/test/net_tests.cpp
index 4a7d6e778f..f4b5768693 100644
--- a/src/test/net_tests.cpp
+++ b/src/test/net_tests.cpp
@@ -23,7 +23,7 @@ public:
     void MakeDeterministic()
     {
         nKey.SetNull();
-        seed_insecure_rand(true);
+        insecure_rand = FastRandomContext(true);
     }
 };
 
diff --git a/src/test/pmt_tests.cpp b/src/test/pmt_tests.cpp
index e9c8691745..b7f83d38f0 100644
--- a/src/test/pmt_tests.cpp
+++ b/src/test/pmt_tests.cpp
@@ -9,7 +9,7 @@
 #include "uint256.h"
 #include "arith_uint256.h"
 #include "version.h"
-#include "random.h"
+#include "test_random.h"
 #include "test/test_bitcoin.h"
 
 #include <vector>
diff --git a/src/test/prevector_tests.cpp b/src/test/prevector_tests.cpp
index b8c45ca564..6cad02e738 100644
--- a/src/test/prevector_tests.cpp
+++ b/src/test/prevector_tests.cpp
@@ -4,7 +4,7 @@
 
 #include <vector>
 #include "prevector.h"
-#include "random.h"
+#include "test_random.h"
 
 #include "serialize.h"
 #include "streams.h"
@@ -27,8 +27,7 @@ class prevector_tester {
 
     typedef typename pretype::size_type Size;
     bool passed = true;
-    uint32_t insecure_rand_Rz_cache;
-    uint32_t insecure_rand_Rw_cache;
+    FastRandomContext rand_cache;
 
 
     template <typename A, typename B>
@@ -171,15 +170,14 @@ public:
         test();
     }
     ~prevector_tester() {
-        BOOST_CHECK_MESSAGE(passed, "insecure_rand_Rz: " 
-                << insecure_rand_Rz_cache 
+        BOOST_CHECK_MESSAGE(passed, "insecure_rand_Rz: "
+                << rand_cache.Rz
                 << ", insecure_rand_Rw: "
-                << insecure_rand_Rw_cache);
+                << rand_cache.Rw);
     }
     prevector_tester() {
         seed_insecure_rand();
-        insecure_rand_Rz_cache = insecure_rand_Rz;
-        insecure_rand_Rw_cache = insecure_rand_Rw;
+        rand_cache = insecure_rand_ctx;
     }
 };
 
diff --git a/src/test/scheduler_tests.cpp b/src/test/scheduler_tests.cpp
index aa12dfbd54..891ecf5015 100644
--- a/src/test/scheduler_tests.cpp
+++ b/src/test/scheduler_tests.cpp
@@ -42,8 +42,6 @@ static void MicroSleep(uint64_t n)
 
 BOOST_AUTO_TEST_CASE(manythreads)
 {
-    seed_insecure_rand(false);
-
     // Stress test: hundreds of microsecond-scheduled tasks,
     // serviced by 10 threads.
     //
@@ -58,7 +56,7 @@ BOOST_AUTO_TEST_CASE(manythreads)
 
     boost::mutex counterMutex[10];
     int counter[10] = { 0 };
-    boost::random::mt19937 rng(insecure_rand());
+    boost::random::mt19937 rng(42);
     boost::random::uniform_int_distribution<> zeroToNine(0, 9);
     boost::random::uniform_int_distribution<> randomMsec(-11, 1000);
     boost::random::uniform_int_distribution<> randomDelta(-1000, 1000);
diff --git a/src/test/sighash_tests.cpp b/src/test/sighash_tests.cpp
index 4a48347b70..0b1050d020 100644
--- a/src/test/sighash_tests.cpp
+++ b/src/test/sighash_tests.cpp
@@ -6,7 +6,7 @@
 #include "data/sighash.json.h"
 #include "hash.h"
 #include "main.h" // For CheckTransaction
-#include "random.h"
+#include "test_random.h"
 #include "script/interpreter.h"
 #include "script/script.h"
 #include "serialize.h"
diff --git a/src/test/skiplist_tests.cpp b/src/test/skiplist_tests.cpp
index f14b902fe1..b19f8fbffb 100644
--- a/src/test/skiplist_tests.cpp
+++ b/src/test/skiplist_tests.cpp
@@ -3,7 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "chain.h"
-#include "random.h"
+#include "test_random.h"
 #include "util.h"
 #include "test/test_bitcoin.h"
 
diff --git a/src/test/test_bitcoin.cpp b/src/test/test_bitcoin.cpp
index 02843d8525..27ea837fbf 100644
--- a/src/test/test_bitcoin.cpp
+++ b/src/test/test_bitcoin.cpp
@@ -27,6 +27,7 @@
 #include <boost/thread.hpp>
 
 std::unique_ptr<CConnman> g_connman;
+FastRandomContext insecure_rand_ctx(true);
 
 extern bool fPrintToConsole;
 extern void noui_connect();
diff --git a/src/test/test_random.h b/src/test/test_random.h
new file mode 100644
index 0000000000..e61b92b7bc
--- /dev/null
+++ b/src/test/test_random.h
@@ -0,0 +1,23 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2014 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_TEST_RANDOM_H
+#define BITCOIN_TEST_RANDOM_H
+
+#include "random.h"
+
+extern FastRandomContext insecure_rand_ctx;
+
+static inline void seed_insecure_rand(bool fDeterministic = false)
+{
+    insecure_rand_ctx = FastRandomContext(fDeterministic);
+}
+
+static inline uint32_t insecure_rand(void)
+{
+    return insecure_rand_ctx.rand32();
+}
+
+#endif
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index efd4498747..0f1c7ab222 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -6,7 +6,7 @@
 
 #include "clientversion.h"
 #include "primitives/transaction.h"
-#include "random.h"
+#include "test_random.h"
 #include "sync.h"
 #include "utilstrencodings.h"
 #include "utilmoneystr.h"
diff --git a/src/test/versionbits_tests.cpp b/src/test/versionbits_tests.cpp
index 1f86a06a3f..ffc0ff6f8e 100644
--- a/src/test/versionbits_tests.cpp
+++ b/src/test/versionbits_tests.cpp
@@ -3,7 +3,7 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "chain.h"
-#include "random.h"
+#include "test_random.h"
 #include "versionbits.h"
 #include "test/test_bitcoin.h"
 #include "chainparams.h"