p2p, refactor: return vector/optional<CService> in `Lookup`

9 files changed, 83 insertions, 100 deletions

diff --git a/src/bench/addrman.cpp b/src/bench/addrman.cpp
index 8a5cab443f..f498071595 100644
--- a/src/bench/addrman.cpp
+++ b/src/bench/addrman.cpp
@@ -79,13 +79,6 @@ static CNetAddr ResolveIP(const std::string& ip)
     return addr;
 }
 
-static CService ResolveService(const std::string& ip, uint16_t port = 0)
-{
-    CService serv;
-    Lookup(ip, serv, port, false);
-    return serv;
-}
-
 /* Benchmarks */
 
 static void AddrManAdd(benchmark::Bench& bench)
@@ -118,8 +111,8 @@ static void AddrManSelectFromAlmostEmpty(benchmark::Bench& bench)
     AddrMan addrman{EMPTY_NETGROUPMAN, /*deterministic=*/false, ADDRMAN_CONSISTENCY_CHECK_RATIO};
 
     // Add one address to the new table
-    CService addr = ResolveService("250.3.1.1", 8333);
-    addrman.Add({CAddress(addr, NODE_NONE)}, ResolveService("250.3.1.1", 8333));
+    CService addr = Lookup("250.3.1.1", 8333, false).value();
+    addrman.Add({CAddress(addr, NODE_NONE)}, addr);
 
     bench.run([&] {
         (void)addrman.Select();
diff --git a/src/init.cpp b/src/init.cpp
index 1ae21ec8d2..846fe7dd72 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1355,12 +1355,12 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     // -noproxy (or -proxy=0) as well as the empty string can be used to not set a proxy, this is the default
     std::string proxyArg = args.GetArg("-proxy", "");
     if (proxyArg != "" && proxyArg != "0") {
-        CService proxyAddr;
-        if (!Lookup(proxyArg, proxyAddr, 9050, fNameLookup)) {
+        const std::optional<CService> proxyAddr{Lookup(proxyArg, 9050, fNameLookup)};
+        if (!proxyAddr.has_value()) {
             return InitError(strprintf(_("Invalid -proxy address or hostname: '%s'"), proxyArg));
         }
 
-        Proxy addrProxy = Proxy(proxyAddr, proxyRandomize);
+        Proxy addrProxy = Proxy(proxyAddr.value(), proxyRandomize);
         if (!addrProxy.IsValid())
             return InitError(strprintf(_("Invalid -proxy address or hostname: '%s'"), proxyArg));
 
@@ -1386,11 +1386,11 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
                       "reaching the Tor network is explicitly forbidden: -onion=0"));
             }
         } else {
-            CService addr;
-            if (!Lookup(onionArg, addr, 9050, fNameLookup) || !addr.IsValid()) {
+            const std::optional<CService> addr{Lookup(onionArg, 9050, fNameLookup)};
+            if (!addr.has_value() || !addr->IsValid()) {
                 return InitError(strprintf(_("Invalid -onion address or hostname: '%s'"), onionArg));
             }
-            onion_proxy = Proxy{addr, proxyRandomize};
+            onion_proxy = Proxy{addr.value(), proxyRandomize};
         }
     }
 
@@ -1410,9 +1410,9 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     }
 
     for (const std::string& strAddr : args.GetArgs("-externalip")) {
-        CService addrLocal;
-        if (Lookup(strAddr, addrLocal, GetListenPort(), fNameLookup) && addrLocal.IsValid())
-            AddLocal(addrLocal, LOCAL_MANUAL);
+        const std::optional<CService> addrLocal{Lookup(strAddr, GetListenPort(), fNameLookup)};
+        if (addrLocal.has_value() && addrLocal->IsValid())
+            AddLocal(addrLocal.value(), LOCAL_MANUAL);
         else
             return InitError(ResolveErrMsg("externalip", strAddr));
     }
@@ -1748,13 +1748,14 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     };
 
     for (const std::string& bind_arg : args.GetArgs("-bind")) {
-        CService bind_addr;
+        std::optional<CService> bind_addr;
         const size_t index = bind_arg.rfind('=');
         if (index == std::string::npos) {
-            if (Lookup(bind_arg, bind_addr, default_bind_port, /*fAllowLookup=*/false)) {
-                connOptions.vBinds.push_back(bind_addr);
-                if (IsBadPort(bind_addr.GetPort())) {
-                    InitWarning(BadPortWarning("-bind", bind_addr.GetPort()));
+            bind_addr = Lookup(bind_arg, default_bind_port, /*fAllowLookup=*/false);
+            if (bind_addr.has_value()) {
+                connOptions.vBinds.push_back(bind_addr.value());
+                if (IsBadPort(bind_addr.value().GetPort())) {
+                    InitWarning(BadPortWarning("-bind", bind_addr.value().GetPort()));
                 }
                 continue;
             }
@@ -1762,8 +1763,9 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
             const std::string network_type = bind_arg.substr(index + 1);
             if (network_type == "onion") {
                 const std::string truncated_bind_arg = bind_arg.substr(0, index);
-                if (Lookup(truncated_bind_arg, bind_addr, BaseParams().OnionServiceTargetPort(), false)) {
-                    connOptions.onion_binds.push_back(bind_addr);
+                bind_addr = Lookup(truncated_bind_arg, BaseParams().OnionServiceTargetPort(), false);
+                if (bind_addr.has_value()) {
+                    connOptions.onion_binds.push_back(bind_addr.value());
                     continue;
                 }
             }
@@ -1841,11 +1843,11 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
 
     const std::string& i2psam_arg = args.GetArg("-i2psam", "");
     if (!i2psam_arg.empty()) {
-        CService addr;
-        if (!Lookup(i2psam_arg, addr, 7656, fNameLookup) || !addr.IsValid()) {
+        const std::optional<CService> addr{Lookup(i2psam_arg, 7656, fNameLookup)};
+        if (!addr.has_value() || !addr->IsValid()) {
             return InitError(strprintf(_("Invalid -i2psam address or hostname: '%s'"), i2psam_arg));
         }
-        SetProxy(NET_I2P, Proxy{addr});
+        SetProxy(NET_I2P, Proxy{addr.value()});
     } else {
         if (args.IsArgSet("-onlynet") && IsReachable(NET_I2P)) {
             return InitError(
diff --git a/src/net.cpp b/src/net.cpp
index 2eba59b9e5..a53835f999 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -130,14 +130,10 @@ uint16_t GetListenPort()
 {
     // If -bind= is provided with ":port" part, use that (first one if multiple are provided).
     for (const std::string& bind_arg : gArgs.GetArgs("-bind")) {
-        CService bind_addr;
         constexpr uint16_t dummy_port = 0;
 
-        if (Lookup(bind_arg, bind_addr, dummy_port, /*fAllowLookup=*/false)) {
-            if (bind_addr.GetPort() != dummy_port) {
-                return bind_addr.GetPort();
-            }
-        }
+        const std::optional<CService> bind_addr{Lookup(bind_arg, dummy_port, /*fAllowLookup=*/false)};
+        if (bind_addr.has_value() && bind_addr->GetPort() != dummy_port) return bind_addr->GetPort();
     }
 
     // Otherwise, if -whitebind= without NetPermissionFlags::NoBan is provided, use that
@@ -461,9 +457,9 @@ CNode* CConnman::ConnectNode(CAddress addrConnect, const char *pszDest, bool fCo
     const uint16_t default_port{pszDest != nullptr ? Params().GetDefaultPort(pszDest) :
                                                      Params().GetDefaultPort()};
     if (pszDest) {
-        std::vector<CService> resolved;
-        if (Lookup(pszDest, resolved,  default_port, fNameLookup && !HaveNameProxy(), 256) && !resolved.empty()) {
-            const CService rnd{resolved[GetRand(resolved.size())]};
+        const std::vector<CService> resolved{Lookup(pszDest, default_port, fNameLookup && !HaveNameProxy(), 256)};
+        if (!resolved.empty()) {
+            const CService& rnd{resolved[GetRand(resolved.size())]};
             addrConnect = CAddress{MaybeFlipIPv6toCJDNS(rnd), NODE_NONE};
             if (!addrConnect.IsValid()) {
                 LogPrint(BCLog::NET, "Resolver returned invalid address %s for %s\n", addrConnect.ToStringAddrPort(), pszDest);
diff --git a/src/net_permissions.cpp b/src/net_permissions.cpp
index f829e56aa2..0013267d98 100644
--- a/src/net_permissions.cpp
+++ b/src/net_permissions.cpp
@@ -88,18 +88,18 @@ bool NetWhitebindPermissions::TryParse(const std::string& str, NetWhitebindPermi
     if (!TryParsePermissionFlags(str, flags, offset, error)) return false;
 
     const std::string strBind = str.substr(offset);
-    CService addrBind;
-    if (!Lookup(strBind, addrBind, 0, false)) {
+    const std::optional<CService> addrBind{Lookup(strBind, 0, false)};
+    if (!addrBind.has_value()) {
         error = ResolveErrMsg("whitebind", strBind);
         return false;
     }
-    if (addrBind.GetPort() == 0) {
+    if (addrBind.value().GetPort() == 0) {
         error = strprintf(_("Need to specify a port with -whitebind: '%s'"), strBind);
         return false;
     }
 
     output.m_flags = flags;
-    output.m_service = addrBind;
+    output.m_service = addrBind.value();
     error = Untranslated("");
     return true;
 }
diff --git a/src/netbase.cpp b/src/netbase.cpp
index 8513974af6..b7eb391a7b 100644
--- a/src/netbase.cpp
+++ b/src/netbase.cpp
@@ -185,35 +185,29 @@ bool LookupHost(const std::string& name, CNetAddr& addr, bool fAllowLookup, DNSL
     return true;
 }
 
-bool Lookup(const std::string& name, std::vector<CService>& vAddr, uint16_t portDefault, bool fAllowLookup, unsigned int nMaxSolutions, DNSLookupFn dns_lookup_function)
+std::vector<CService> Lookup(const std::string& name, uint16_t portDefault, bool fAllowLookup, unsigned int nMaxSolutions, DNSLookupFn dns_lookup_function)
 {
     if (name.empty() || !ContainsNoNUL(name)) {
-        return false;
+        return {};
     }
     uint16_t port{portDefault};
     std::string hostname;
     SplitHostPort(name, port, hostname);
 
     const std::vector<CNetAddr> addresses{LookupIntern(hostname, nMaxSolutions, fAllowLookup, dns_lookup_function)};
-    if (addresses.empty())
-        return false;
-    vAddr.resize(addresses.size());
-    for (unsigned int i = 0; i < addresses.size(); i++)
-        vAddr[i] = CService(addresses[i], port);
-    return true;
+    if (addresses.empty()) return {};
+    std::vector<CService> services;
+    services.reserve(addresses.size());
+    for (const auto& addr : addresses)
+        services.emplace_back(addr, port);
+    return services;
 }
 
-bool Lookup(const std::string& name, CService& addr, uint16_t portDefault, bool fAllowLookup, DNSLookupFn dns_lookup_function)
+std::optional<CService> Lookup(const std::string& name, uint16_t portDefault, bool fAllowLookup, DNSLookupFn dns_lookup_function)
 {
-    if (!ContainsNoNUL(name)) {
-        return false;
-    }
-    std::vector<CService> vService;
-    bool fRet = Lookup(name, vService, portDefault, fAllowLookup, 1, dns_lookup_function);
-    if (!fRet)
-        return false;
-    addr = vService[0];
-    return true;
+    const std::vector<CService> services{Lookup(name, portDefault, fAllowLookup, 1, dns_lookup_function)};
+
+    return services.empty() ? std::nullopt : std::make_optional(services.front());
 }
 
 CService LookupNumeric(const std::string& name, uint16_t portDefault, DNSLookupFn dns_lookup_function)
@@ -221,12 +215,9 @@ CService LookupNumeric(const std::string& name, uint16_t portDefault, DNSLookupF
     if (!ContainsNoNUL(name)) {
         return {};
     }
-    CService addr;
     // "1.2:345" will fail to resolve the ip, but will still set the port.
     // If the ip fails to resolve, re-init the result.
-    if(!Lookup(name, addr, portDefault, false, dns_lookup_function))
-        addr = CService();
-    return addr;
+    return Lookup(name, portDefault, /*fAllowLookup=*/false, dns_lookup_function).value_or(CService{});
 }
 
 /** SOCKS version */
diff --git a/src/netbase.h b/src/netbase.h
index dde5e5b43c..6c972b81eb 100644
--- a/src/netbase.h
+++ b/src/netbase.h
@@ -109,7 +109,7 @@ extern DNSLookupFn g_dns_lookup;
  * @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)
+ * @see Lookup(const std::string&, uint16_t, bool, unsigned int, DNSLookupFn)
  *      for additional parameter descriptions.
  */
 std::vector<CNetAddr> LookupHost(const std::string& name, unsigned int nMaxSolutions, bool fAllowLookup, DNSLookupFn dns_lookup_function = g_dns_lookup);
@@ -133,8 +133,6 @@ bool LookupHost(const std::string& name, CNetAddr& addr, bool fAllowLookup, DNSL
  *                disambiguated bracketed form), optionally followed by a uint16_t port
  *                number. (e.g. example.com:8333 or
  *                [2001:db8:85a3:8d3:1319:8a2e:370:7348]:420)
- * @param[out] vAddr The resulting services to which the specified service string
- *                   resolved.
  * @param portDefault The default port for resulting services if not specified
  *                    by the service string.
  * @param fAllowLookup Whether or not hostname lookups are permitted. If yes,
@@ -142,18 +140,18 @@ bool LookupHost(const std::string& name, CNetAddr& addr, bool fAllowLookup, DNSL
  * @param nMaxSolutions The maximum number of results we want, specifying 0
  *                      means "as many solutions as we get."
  *
- * @returns Whether or not the service string successfully resolved to any
- *          resulting services.
+ * @returns The resulting services to which the specified service string
+ *          resolved.
  */
-bool Lookup(const std::string& name, std::vector<CService>& vAddr, uint16_t portDefault, bool fAllowLookup, unsigned int nMaxSolutions, DNSLookupFn dns_lookup_function = g_dns_lookup);
+std::vector<CService> Lookup(const std::string& name, uint16_t portDefault, bool fAllowLookup, unsigned int nMaxSolutions, DNSLookupFn dns_lookup_function = g_dns_lookup);
 
 /**
  * Resolve a service string to its first corresponding service.
  *
- * @see Lookup(const std::string&, std::vector<CService>&, uint16_t, bool, unsigned int, DNSLookupFn)
+ * @see Lookup(const std::string&, uint16_t, bool, unsigned int, DNSLookupFn)
  *      for additional parameter descriptions.
  */
-bool Lookup(const std::string& name, CService& addr, uint16_t portDefault, bool fAllowLookup, DNSLookupFn dns_lookup_function = g_dns_lookup);
+std::optional<CService> Lookup(const std::string& name, uint16_t portDefault, bool fAllowLookup, DNSLookupFn dns_lookup_function = g_dns_lookup);
 
 /**
  * Resolve a service string with a numeric IP to its first corresponding
@@ -161,7 +159,7 @@ bool Lookup(const std::string& name, CService& addr, uint16_t portDefault, bool
  *
  * @returns The resulting CService if the resolution was successful, [::]:0 otherwise.
  *
- * @see Lookup(const std::string&, std::vector<CService>&, uint16_t, bool, unsigned int, DNSLookupFn)
+ * @see Lookup(const std::string&, uint16_t, bool, unsigned int, DNSLookupFn)
  *      for additional parameter descriptions.
  */
 CService LookupNumeric(const std::string& name, uint16_t portDefault = 0, DNSLookupFn dns_lookup_function = g_dns_lookup);
diff --git a/src/test/addrman_tests.cpp b/src/test/addrman_tests.cpp
index 54d923e4a4..95dbaa449b 100644
--- a/src/test/addrman_tests.cpp
+++ b/src/test/addrman_tests.cpp
@@ -40,9 +40,9 @@ static CNetAddr ResolveIP(const std::string& ip)
 
 static CService ResolveService(const std::string& ip, uint16_t port = 0)
 {
-    CService serv;
-    BOOST_CHECK_MESSAGE(Lookup(ip, serv, port, false), strprintf("failed to resolve: %s:%i", ip, port));
-    return serv;
+    const std::optional<CService> serv{Lookup(ip, port, false)};
+    BOOST_CHECK_MESSAGE(serv.has_value(), strprintf("failed to resolve: %s:%i", ip, port));
+    return serv.value_or(CService{});
 }
 
 
@@ -948,18 +948,23 @@ BOOST_AUTO_TEST_CASE(load_addrman)
 {
     AddrMan addrman{EMPTY_NETGROUPMAN, DETERMINISTIC, GetCheckRatio(m_node)};
 
-    CService addr1, addr2, addr3;
-    BOOST_CHECK(Lookup("250.7.1.1", addr1, 8333, false));
-    BOOST_CHECK(Lookup("250.7.2.2", addr2, 9999, false));
-    BOOST_CHECK(Lookup("250.7.3.3", addr3, 9999, false));
-    BOOST_CHECK(Lookup("250.7.3.3"s, addr3, 9999, false));
-    BOOST_CHECK(!Lookup("250.7.3.3\0example.com"s, addr3, 9999, false));
+    std::optional<CService> addr1, addr2, addr3, addr4;
+    addr1 = Lookup("250.7.1.1", 8333, false);
+    BOOST_CHECK(addr1.has_value());
+    addr2 = Lookup("250.7.2.2", 9999, false);
+    BOOST_CHECK(addr2.has_value());
+    addr3 = Lookup("250.7.3.3", 9999, false);
+    BOOST_CHECK(addr3.has_value());
+    addr3 = Lookup("250.7.3.3"s, 9999, false);
+    BOOST_CHECK(addr3.has_value());
+    addr4 = Lookup("250.7.3.3\0example.com"s, 9999, false);
+    BOOST_CHECK(!addr4.has_value());
 
     // Add three addresses to new table.
-    CService source;
-    BOOST_CHECK(Lookup("252.5.1.1", source, 8333, false));
-    std::vector<CAddress> addresses{CAddress(addr1, NODE_NONE), CAddress(addr2, NODE_NONE), CAddress(addr3, NODE_NONE)};
-    BOOST_CHECK(addrman.Add(addresses, source));
+    const std::optional<CService> source{Lookup("252.5.1.1", 8333, false)};
+    BOOST_CHECK(source.has_value());
+    std::vector<CAddress> addresses{CAddress(addr1.value(), NODE_NONE), CAddress(addr2.value(), NODE_NONE), CAddress(addr3.value(), NODE_NONE)};
+    BOOST_CHECK(addrman.Add(addresses, source.value()));
     BOOST_CHECK(addrman.Size() == 3);
 
     // Test that the de-serialization does not throw an exception.
@@ -1004,11 +1009,11 @@ static CDataStream MakeCorruptPeersDat()
     int nUBuckets = ADDRMAN_NEW_BUCKET_COUNT ^ (1 << 30);
     s << nUBuckets;
 
-    CService serv;
-    BOOST_CHECK(Lookup("252.1.1.1", serv, 7777, false));
-    CAddress addr = CAddress(serv, NODE_NONE);
+    const std::optional<CService> serv{Lookup("252.1.1.1", 7777, false)};
+    BOOST_REQUIRE(serv.has_value());
+    CAddress addr = CAddress(serv.value(), NODE_NONE);
     CNetAddr resolved;
-    BOOST_CHECK(LookupHost("252.2.2.2", resolved, false));
+    BOOST_REQUIRE(LookupHost("252.2.2.2", resolved, false));
     AddrInfo info = AddrInfo(addr, resolved);
     s << info;
 
diff --git a/src/test/fuzz/netbase_dns_lookup.cpp b/src/test/fuzz/netbase_dns_lookup.cpp
index a47c09b683..47289ccbee 100644
--- a/src/test/fuzz/netbase_dns_lookup.cpp
+++ b/src/test/fuzz/netbase_dns_lookup.cpp
@@ -42,18 +42,16 @@ FUZZ_TARGET(netbase_dns_lookup)
         }
     }
     {
-        std::vector<CService> resolved_services;
-        if (Lookup(name, resolved_services, default_port, allow_lookup, max_results, fuzzed_dns_lookup_function)) {
-            for (const CNetAddr& resolved_service : resolved_services) {
-                assert(!resolved_service.IsInternal());
-            }
+        const std::vector<CService> resolved_services{Lookup(name, default_port, allow_lookup, max_results, fuzzed_dns_lookup_function)};
+        for (const CNetAddr& resolved_service : resolved_services) {
+            assert(!resolved_service.IsInternal());
         }
         assert(resolved_services.size() <= max_results || max_results == 0);
     }
     {
-        CService resolved_service;
-        if (Lookup(name, resolved_service, default_port, allow_lookup, fuzzed_dns_lookup_function)) {
-            assert(!resolved_service.IsInternal());
+        const std::optional<CService> resolved_service{Lookup(name, default_port, allow_lookup, fuzzed_dns_lookup_function)};
+        if (resolved_service.has_value()) {
+            assert(!resolved_service.value().IsInternal());
         }
     }
     {
diff --git a/src/torcontrol.cpp b/src/torcontrol.cpp
index 92b55f9fc4..98d68f93e9 100644
--- a/src/torcontrol.cpp
+++ b/src/torcontrol.cpp
@@ -133,15 +133,15 @@ bool TorControlConnection::Connect(const std::string& tor_control_center, const
         Disconnect();
     }
 
-    CService control_service;
-    if (!Lookup(tor_control_center, control_service, 9051, fNameLookup)) {
+    const std::optional<CService> control_service{Lookup(tor_control_center, 9051, fNameLookup)};
+    if (!control_service.has_value()) {
         LogPrintf("tor: Failed to look up control center %s\n", tor_control_center);
         return false;
     }
 
     struct sockaddr_storage control_address;
     socklen_t control_address_len = sizeof(control_address);
-    if (!control_service.GetSockAddr(reinterpret_cast<struct sockaddr*>(&control_address), &control_address_len)) {
+    if (!control_service.value().GetSockAddr(reinterpret_cast<struct sockaddr*>(&control_address), &control_address_len)) {
         LogPrintf("tor: Error parsing socket address %s\n", tor_control_center);
         return false;
     }