util: simplify the interface of serviceFlagToStr()

Don't take two redundant arguments in `serviceFlagToStr()`.

As a side effect this fixes an issue introduced in
bitcoin/bitcoin#18165 due to which the GUI could
print something like `UNKNOWN[1033] & UNKNOWN[1033] & UNKNOWN[2^10]`
instead of `NETWORK & WITNESS`.

Author: vasild

src/protocol.cpp

@@ -195,9 +195,10 @@ const std::vector<std::string> &getAllNetMessageTypes()
     return allNetMessageTypesVec;
 }
 
-std::string serviceFlagToStr(const uint64_t mask, const int bit)
+std::string serviceFlagToStr(size_t bit)
 {
-    switch (ServiceFlags(mask)) {
+    const uint64_t service_flag = 1ULL << bit;
+    switch ((ServiceFlags)service_flag) {
     case NODE_NONE: abort();  // impossible
     case NODE_NETWORK:         return "NETWORK";
     case NODE_GETUTXO:         return "GETUTXO";
@@ -211,7 +212,7 @@ std::string serviceFlagToStr(const uint64_t mask, const int bit)
     stream.imbue(std::locale::classic());
     stream << "UNKNOWN[";
     if (bit < 8) {
-        stream << mask;
+        stream << service_flag;
     } else {
         stream << "2^" << bit;
     }

src/protocol.h

@@ -288,7 +288,12 @@ enum ServiceFlags : uint64_t {
     // BIP process.
 };
 
-std::string serviceFlagToStr(uint64_t mask, int bit);
+/**
+ * Convert a service flag (NODE_*) to a human readable string.
+ * It supports unknown service flags which will be returned as "UNKNOWN[...]".
+ * @param[in] bit the service flag is calculated as (1 << bit)
+ */
+std::string serviceFlagToStr(size_t bit);
 
 /**
  * Gets the set of service flags which are "desirable" for a given peer.

src/qt/guiutil.cpp

@@ -759,7 +759,7 @@ QString formatServicesStr(quint64 mask)
         uint64_t check = 1ull << i;
         if (mask & check)
         {
-            strList.append(QString::fromStdString(serviceFlagToStr(mask, i)));
+            strList.append(QString::fromStdString(serviceFlagToStr(i)));
         }
     }
 

src/rpc/util.cpp

@@ -847,7 +847,7 @@ UniValue GetServicesNames(ServiceFlags services)
     for (int i = 0; i < 64; ++i) {
         const uint64_t mask = 1ull << i;
         if (services_n & mask) {
-            servicesNames.push_back(serviceFlagToStr(mask, i));
+            servicesNames.push_back(serviceFlagToStr(i));
         }
     }