[rpc] Add logging RPC

Adds an RPC to get and set currently active logging categories.

Author: jnewbery

src/rpc/client.cpp

@@ -113,6 +113,8 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "getmempoolancestors", 1, "verbose" },
     { "getmempooldescendants", 1, "verbose" },
     { "bumpfee", 1, "options" },
+    { "logging", 0, "include" },
+    { "logging", 1, "exclude" },
     // Echo with conversion (For testing only)
     { "echojson", 0, "arg0" },
     { "echojson", 1, "arg1" },

src/rpc/misc.cpp

@@ -555,6 +555,59 @@ UniValue getmemoryinfo(const JSONRPCRequest& request)
     }
 }
 
+uint32_t getCategoryMask(UniValue cats) {
+    cats = cats.get_array();
+    uint32_t mask = 0;
+    for (unsigned int i = 0; i < cats.size(); ++i) {
+        uint32_t flag = 0;
+        std::string cat = cats[i].get_str();
+        if (!GetLogCategory(&flag, &cat)) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "unknown logging category " + cat);
+        }
+        mask |= flag;
+    }
+    return mask;
+}
+
+UniValue logging(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() > 2) {
+        throw std::runtime_error(
+            "logging [include,...] <exclude>\n"
+            "Gets and sets the logging configuration.\n"
+            "When called without an argument, returns the list of categories that are currently being debug logged.\n"
+            "When called with arguments, adds or removes categories from debug logging.\n"
+            "The valid logging categories are: " + ListLogCategories() + "\n"
+            "libevent logging is configured on startup and cannot be modified by this RPC during runtime."
+            "Arguments:\n"
+            "1. \"include\" (array of strings) add debug logging for these categories.\n"
+            "2. \"exclude\" (array of strings) remove debug logging for these categories.\n"
+            "\nResult: <categories>  (string): a list of the logging categories that are active.\n"
+            "\nExamples:\n"
+            + HelpExampleCli("logging", "\"[\\\"all\\\"]\" \"[\\\"http\\\"]\"")
+            + HelpExampleRpc("logging", "[\"all\"], \"[libevent]\"")
+        );
+    }
+
+    uint32_t originalLogCategories = logCategories;
+    if (request.params.size() > 0 && request.params[0].isArray()) {
+        logCategories |= getCategoryMask(request.params[0]);
+    }
+
+    if (request.params.size() > 1 && request.params[1].isArray()) {
+        logCategories &= ~getCategoryMask(request.params[1]);
+    }
+
+
+    UniValue result(UniValue::VOBJ);
+    std::vector<CLogCategoryActive> vLogCatActive = ListActiveLogCategories();
+    for (const auto& logCatActive : vLogCatActive) {
+        result.pushKV(logCatActive.category, logCatActive.active);
+    }
+
+    return result;
+}
+
 UniValue echo(const JSONRPCRequest& request)
 {
     if (request.fHelp)
@@ -581,7 +634,8 @@ static const CRPCCommand commands[] =
     /* Not shown in help */
     { "hidden",             "setmocktime",            &setmocktime,            true,  {"timestamp"}},
     { "hidden",             "echo",                   &echo,                   true,  {"arg0","arg1","arg2","arg3","arg4","arg5","arg6","arg7","arg8","arg9"}},
-    { "hidden",             "echojson",               &echo,                  true,  {"arg0","arg1","arg2","arg3","arg4","arg5","arg6","arg7","arg8","arg9"}},
+    { "hidden",             "echojson",               &echo,                   true,  {"arg0","arg1","arg2","arg3","arg4","arg5","arg6","arg7","arg8","arg9"}},
+    { "hidden",             "logging",                &logging,                true,  {"include", "exclude"}},
 };
 
 void RegisterMiscRPCCommands(CRPCTable &t)

src/util.cpp

@@ -118,7 +118,7 @@ bool fLogIPs = DEFAULT_LOGIPS;
 std::atomic<bool> fReopenDebugLog(false);
 CTranslationInterface translationInterface;
 
-/** Log categories bitfield. Leveldb/libevent need special handling if their flags are changed at runtime. */
+/** Log categories bitfield. libevent needs special handling if their flags are changed at runtime. */
 std::atomic<uint32_t> logCategories(0);
 
 /** Init OpenSSL library multithreading support */
@@ -295,6 +295,21 @@ std::string ListLogCategories()
     return ret;
 }
 
+std::vector<CLogCategoryActive> ListActiveLogCategories()
+{
+    std::vector<CLogCategoryActive> ret;
+    for (unsigned int i = 0; i < ARRAYLEN(LogCategories); i++) {
+        // Omit the special cases.
+        if (LogCategories[i].flag != BCLog::NONE && LogCategories[i].flag != BCLog::ALL) {
+            CLogCategoryActive catActive;
+            catActive.category = LogCategories[i].category;
+            catActive.active = LogAcceptCategory(LogCategories[i].flag);
+            ret.push_back(catActive);
+        }
+    }
+    return ret;
+}
+
 /**
  * fStartedNewLine is a state variable held by the calling context that will
  * suppress printing of the timestamp when multiple calls are made that don't

src/util.h

@@ -69,6 +69,12 @@ inline std::string _(const char* psz)
 void SetupEnvironment();
 bool SetupNetworking();
 
+struct CLogCategoryActive
+{
+    std::string category;
+    bool active;
+};
+
 namespace BCLog {
     enum LogFlags : uint32_t {
         NONE        = 0,
@@ -102,9 +108,12 @@ static inline bool LogAcceptCategory(uint32_t category)
     return (logCategories.load(std::memory_order_relaxed) & category) != 0;
 }
 
-/** Returns a string with the supported log categories */
+/** Returns a string with the log categories. */
 std::string ListLogCategories();
 
+/** Returns a vector of the active log categories. */
+std::vector<CLogCategoryActive> ListActiveLogCategories();
+
 /** Return true if str parses as a log category and set the flags in f */
 bool GetLogCategory(uint32_t *f, const std::string *str);