p2p, refactor: return std::vector<CNetAddr> in LookupHost

Author: brunoerg

src/net.cpp

@@ -1487,7 +1487,6 @@ void CConnman::ThreadDNSAddressSeed()
         if (HaveNameProxy()) {
             AddAddrFetch(seed);
         } else {
-            std::vector<CNetAddr> vIPs;
             std::vector<CAddress> vAdd;
             ServiceFlags requiredServiceBits = GetDesirableServiceFlags(NODE_NONE);
             std::string host = strprintf("x%x.%s", requiredServiceBits, seed);
@@ -1496,8 +1495,9 @@ void CConnman::ThreadDNSAddressSeed()
                 continue;
             }
             unsigned int nMaxIPs = 256; // Limits number of IPs learned from a DNS seed
-            if (LookupHost(host, vIPs, nMaxIPs, true)) {
-                for (const CNetAddr& ip : vIPs) {
+            const auto addresses{LookupHost(host, nMaxIPs, true)};
+            if (!addresses.empty()) {
+                for (const CNetAddr& ip : addresses) {
                     CAddress addr = CAddress(CService(ip, Params().GetDefaultPort()), requiredServiceBits);
                     addr.nTime = rng.rand_uniform_delay(Now<NodeSeconds>() - 3 * 24h, -4 * 24h); // use a random age between 3 and 7 days old
                     vAdd.push_back(addr);
@@ -2201,14 +2201,11 @@ void Discover()
     char pszHostName[256] = "";
     if (gethostname(pszHostName, sizeof(pszHostName)) != SOCKET_ERROR)
     {
-        std::vector<CNetAddr> vaddr;
-        if (LookupHost(pszHostName, vaddr, 0, true))
+        const std::vector<CNetAddr> addresses{LookupHost(pszHostName, 0, true)};
+        for (const CNetAddr& addr : addresses)
         {
-            for (const CNetAddr &addr : vaddr)
-            {
-                if (AddLocal(addr, LOCAL_IF))
-                    LogPrintf("%s: %s - %s\n", __func__, pszHostName, addr.ToStringAddr());
-            }
+            if (AddLocal(addr, LOCAL_IF))
+                LogPrintf("%s: %s - %s\n", __func__, pszHostName, addr.ToStringAddr());
         }
     }
 #elif (HAVE_DECL_GETIFADDRS && HAVE_DECL_FREEIFADDRS)

src/netbase.cpp

@@ -161,32 +161,27 @@ static std::vector<CNetAddr> LookupIntern(const std::string& name, unsigned int
     return addresses;
 }
 
-bool LookupHost(const std::string& name, std::vector<CNetAddr>& addresses, unsigned int nMaxSolutions, bool fAllowLookup, DNSLookupFn dns_lookup_function)
+std::vector<CNetAddr> LookupHost(const std::string& name, unsigned int nMaxSolutions, bool fAllowLookup, DNSLookupFn dns_lookup_function)
 {
-    if (!ContainsNoNUL(name)) {
-        return false;
-    }
+    if (!ContainsNoNUL(name)) return {};
     std::string strHost = name;
-    if (strHost.empty())
-        return false;
+    if (strHost.empty()) return {};
     if (strHost.front() == '[' && strHost.back() == ']') {
         strHost = strHost.substr(1, strHost.size() - 2);
     }
 
-    addresses = LookupIntern(strHost, nMaxSolutions, fAllowLookup, dns_lookup_function);
-    return addresses.size() > 0;
+    return LookupIntern(strHost, nMaxSolutions, fAllowLookup, dns_lookup_function);
 }
 
 bool LookupHost(const std::string& name, CNetAddr& addr, bool fAllowLookup, DNSLookupFn dns_lookup_function)
 {
     if (!ContainsNoNUL(name)) {
         return false;
     }
-    std::vector<CNetAddr> vIP;
-    LookupHost(name, vIP, 1, fAllowLookup, dns_lookup_function);
-    if(vIP.empty())
+    const std::vector<CNetAddr> addresses{LookupHost(name, 1, fAllowLookup, dns_lookup_function)};
+    if(addresses.empty())
         return false;
-    addr = vIP.front();
+    addr = addresses.front();
     return true;
 }
 

src/netbase.h

@@ -105,21 +105,22 @@ extern DNSLookupFn g_dns_lookup;
  * @param name    The string representing a host. Could be a name or a numerical
  *                IP address (IPv6 addresses in their bracketed form are
  *                allowed).
- * @param[out] vIP The resulting network addresses to which the specified host
- *                 string resolved.
  *
- * @returns Whether or not the specified host string successfully resolved to
- *          any resulting network addresses.
+ * @returns The resulting network addresses to which the specified host
+ *          string resolved.
  *
  * @see Lookup(const std::string&, std::vector<CService>&, uint16_t, bool, unsigned int, DNSLookupFn)
  *      for additional parameter descriptions.
  */
-bool LookupHost(const std::string& name, std::vector<CNetAddr>& vIP, unsigned int nMaxSolutions, bool fAllowLookup, DNSLookupFn dns_lookup_function = g_dns_lookup);
+std::vector<CNetAddr> LookupHost(const std::string& name, unsigned int nMaxSolutions, bool fAllowLookup, DNSLookupFn dns_lookup_function = g_dns_lookup);
 
 /**
  * Resolve a host string to its first corresponding network address.
  *
- * @see LookupHost(const std::string&, std::vector<CNetAddr>&, uint16_t, bool, DNSLookupFn)
+ * @returns The resulting network addresses to which the specified host
+ *          string resolved.
+ *
+ * @see LookupHost(const std::string&, uint16_t, bool, DNSLookupFn)
  *      for additional parameter descriptions.
  */
 bool LookupHost(const std::string& name, CNetAddr& addr, bool fAllowLookup, DNSLookupFn dns_lookup_function = g_dns_lookup);

src/test/fuzz/netbase_dns_lookup.cpp

@@ -29,11 +29,9 @@ FUZZ_TARGET(netbase_dns_lookup)
     };
 
     {
-        std::vector<CNetAddr> resolved_addresses;
-        if (LookupHost(name, resolved_addresses, max_results, allow_lookup, fuzzed_dns_lookup_function)) {
-            for (const CNetAddr& resolved_address : resolved_addresses) {
-                assert(!resolved_address.IsInternal());
-            }
+        const std::vector<CNetAddr> resolved_addresses{LookupHost(name, max_results, allow_lookup, fuzzed_dns_lookup_function)};
+        for (const CNetAddr& resolved_address : resolved_addresses) {
+            assert(!resolved_address.IsInternal());
         }
         assert(resolved_addresses.size() <= max_results || max_results == 0);
     }