Merge bitcoin/bitcoin#26261: p2p: cleanup `LookupIntern`, `Lookup` and `LookupHost`

5c832c3820253affc65c0ed490e26e5b0a4d5c9b p2p, refactor: return `std::optional<CNetAddr>` in `LookupHost` (brunoerg)
34bcdfc6a65de906c65edccdd96fe15219081cd2 p2p, refactor: return vector/optional<CService> in `Lookup` (brunoerg)
7799eb125b7a1146f8251be5d26df574236212a9 p2p, refactor: return `std::vector<CNetAddr>` in `LookupHost` (brunoerg)
5c1774a563dcc237a88df69569cd94fe81e908f7 p2p, refactor: return `std::vector<CNetAddr>` in `LookupIntern` (brunoerg)

Pull request description:

  Continuation of #26078.

  To improve readability instead of returning a bool and passing stuff by reference, this PR changes:

  - `LookupHost` to return `std::vector<CNetAddr>`
  - `LookupHost` to return `std::optional<CNetAddr>`
  - `Lookup` to return `std::vector<CService>`
  - `Lookup` to return `std::optional<CService>`.
  - `LookupIntern` to return `std::vector<CNetAddr>`

  As discussed in #26078, it would be better to avoid using `optional` in some cases, but for specific `Lookup` and `LookupHost` functions it's necessary to use `optional` to verify if they were able to catch some data from their overloaded function.

ACKs for top commit:
  achow101:
    ACK 5c832c3820253affc65c0ed490e26e5b0a4d5c9b
  stickies-v:
    re-ACK 5c832c3820253affc65c0ed490e26e5b0a4d5c9b - just addressing two nits, no other changes
  theStack:
    re-ACK 5c832c3820253affc65c0ed490e26e5b0a4d5c9b

Tree-SHA512: ea346fdc54463999646269bd600cd4a1590ef958001d2f0fc2be608ca51e1b4365efccca76dd4972b023e12fcc6e67d226608b0df7beb901bdeadd19948df840

16 files changed, 171 insertions, 225 deletions

diff --git a/src/bench/addrman.cpp b/src/bench/addrman.cpp
index 8a5cab443f..f044feebba 100644
--- a/src/bench/addrman.cpp
+++ b/src/bench/addrman.cpp
@@ -72,20 +72,6 @@ static void FillAddrMan(AddrMan& addrman)
     AddAddressesToAddrMan(addrman);
 }
 
-static CNetAddr ResolveIP(const std::string& ip)
-{
-    CNetAddr addr;
-    LookupHost(ip, addr, false);
-    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 +104,8 @@ 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();
@@ -135,7 +121,7 @@ static void AddrManSelectByNetwork(benchmark::Bench& bench)
     i2p_service.SetSpecial("udhdrtrcetjm5sxzskjyr5ztpeszydbh4dpl3pl4utgqqw2v4jna.b32.i2p");
     CAddress i2p_address(i2p_service, NODE_NONE);
     i2p_address.nTime = Now<NodeSeconds>();
-    CNetAddr source = ResolveIP("252.2.2.2");
+    const CNetAddr source{LookupHost("252.2.2.2", false).value()};
     addrman.Add({i2p_address}, source);
 
     FillAddrMan(addrman);
diff --git a/src/httpserver.cpp b/src/httpserver.cpp
index 4f8a2b4d8d..128c4e3c56 100644
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -170,12 +170,8 @@ static bool ClientAllowed(const CNetAddr& netaddr)
 static bool InitHTTPAllowList()
 {
     rpc_allow_subnets.clear();
-    CNetAddr localv4;
-    CNetAddr localv6;
-    LookupHost("127.0.0.1", localv4, false);
-    LookupHost("::1", localv6, false);
-    rpc_allow_subnets.push_back(CSubNet(localv4, 8));      // always allow IPv4 local subnet
-    rpc_allow_subnets.push_back(CSubNet(localv6));         // always allow IPv6 localhost
+    rpc_allow_subnets.push_back(CSubNet{LookupHost("127.0.0.1", false).value(), 8});  // always allow IPv4 local subnet
+    rpc_allow_subnets.push_back(CSubNet{LookupHost("::1", false).value()});  // always allow IPv6 localhost
     for (const std::string& strAllow : gArgs.GetArgs("-rpcallowip")) {
         CSubNet subnet;
         LookupSubNet(strAllow, subnet);
@@ -338,8 +334,8 @@ static bool HTTPBindAddresses(struct evhttp* http)
         LogPrintf("Binding RPC on address %s port %i\n", i->first, i->second);
         evhttp_bound_socket *bind_handle = evhttp_bind_socket_with_handle(http, i->first.empty() ? nullptr : i->first.c_str(), i->second);
         if (bind_handle) {
-            CNetAddr addr;
-            if (i->first.empty() || (LookupHost(i->first, addr, false) && addr.IsBindAny())) {
+            const std::optional<CNetAddr> addr{LookupHost(i->first, false)};
+            if (i->first.empty() || (addr.has_value() && addr->IsBindAny())) {
                 LogPrintf("WARNING: the RPC server is not safe to expose to untrusted networks such as the public internet\n");
             }
             boundSockets.push_back(bind_handle);
diff --git a/src/init.cpp b/src/init.cpp
index d9e5e70ee3..e8c804b9a7 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1359,12 +1359,12 @@ 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));
 
@@ -1390,11 +1390,11 @@ 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};
         }
     }
 
@@ -1414,9 +1414,9 @@ 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));
     }
@@ -1754,13 +1754,14 @@ 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;
             }
@@ -1768,8 +1769,9 @@ 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;
                 }
             }
@@ -1847,11 +1849,11 @@ 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/mapport.cpp b/src/mapport.cpp
index 76f8a4d0c9..118827901a 100644
--- a/src/mapport.cpp
+++ b/src/mapport.cpp
@@ -175,10 +175,10 @@ static bool ProcessUpnp()
                 LogPrintf("UPnP: GetExternalIPAddress() returned %d\n", r);
             } else {
                 if (externalIPAddress[0]) {
-                    CNetAddr resolved;
-                    if (LookupHost(externalIPAddress, resolved, false)) {
-                        LogPrintf("UPnP: ExternalIPAddress = %s\n", resolved.ToStringAddr());
-                        AddLocal(resolved, LOCAL_MAPPED);
+                    std::optional<CNetAddr> resolved{LookupHost(externalIPAddress, false)};
+                    if (resolved.has_value()) {
+                        LogPrintf("UPnP: ExternalIPAddress = %s\n", resolved->ToStringAddr());
+                        AddLocal(resolved.value(), LOCAL_MAPPED);
                     }
                 } else {
                     LogPrintf("UPnP: GetExternalIPAddress failed.\n");
diff --git a/src/net.cpp b/src/net.cpp
index 337cf60680..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);
@@ -1487,7 +1483,6 @@ 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 +1491,9 @@ 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 +2197,11 @@ 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)
diff --git a/src/net_permissions.cpp b/src/net_permissions.cpp
index 1e4ec5b529..23226bbb4f 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 4f78d2e31a..8f6f92ea7d 100644
--- a/src/netbase.cpp
+++ b/src/netbase.cpp
@@ -132,14 +132,9 @@ std::vector<std::string> GetNetworkNames(bool append_unroutable)
     return names;
 }
 
-static bool LookupIntern(const std::string& name, std::vector<CNetAddr>& vIP, unsigned int nMaxSolutions, bool fAllowLookup, DNSLookupFn dns_lookup_function)
+static std::vector<CNetAddr> LookupIntern(const std::string& name, unsigned int nMaxSolutions, bool fAllowLookup, DNSLookupFn dns_lookup_function)
 {
-    vIP.clear();
-
-    if (!ContainsNoNUL(name)) {
-        return false;
-    }
-
+    if (!ContainsNoNUL(name)) return {};
     {
         CNetAddr addr;
         // From our perspective, onion addresses are not hostnames but rather
@@ -148,83 +143,65 @@ static bool LookupIntern(const std::string& name, std::vector<CNetAddr>& vIP, un
         // getaddrinfo to decode them and it wouldn't make sense to resolve
         // them, we return a network address representing it instead. See
         // CNetAddr::SetSpecial(const std::string&) for more details.
-        if (addr.SetSpecial(name)) {
-            vIP.push_back(addr);
-            return true;
-        }
+        if (addr.SetSpecial(name)) return {addr};
     }
 
+    std::vector<CNetAddr> addresses;
+
     for (const CNetAddr& resolved : dns_lookup_function(name, fAllowLookup)) {
-        if (nMaxSolutions > 0 && vIP.size() >= nMaxSolutions) {
+        if (nMaxSolutions > 0 && addresses.size() >= nMaxSolutions) {
             break;
         }
         /* Never allow resolving to an internal address. Consider any such result invalid */
         if (!resolved.IsInternal()) {
-            vIP.push_back(resolved);
+            addresses.push_back(resolved);
         }
     }
 
-    return (vIP.size() > 0);
+    return addresses;
 }
 
-bool LookupHost(const std::string& name, std::vector<CNetAddr>& vIP, 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);
     }
 
-    return LookupIntern(strHost, vIP, nMaxSolutions, fAllowLookup, dns_lookup_function);
+    return LookupIntern(strHost, nMaxSolutions, fAllowLookup, dns_lookup_function);
 }
 
-bool LookupHost(const std::string& name, CNetAddr& addr, bool fAllowLookup, DNSLookupFn dns_lookup_function)
+std::optional<CNetAddr> LookupHost(const std::string& name, 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())
-        return false;
-    addr = vIP.front();
-    return true;
+    const std::vector<CNetAddr> addresses{LookupHost(name, 1, fAllowLookup, dns_lookup_function)};
+    return addresses.empty() ? std::nullopt : std::make_optional(addresses.front());
 }
 
-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);
 
-    std::vector<CNetAddr> vIP;
-    bool fRet = LookupIntern(hostname, vIP, nMaxSolutions, fAllowLookup, dns_lookup_function);
-    if (!fRet)
-        return false;
-    vAddr.resize(vIP.size());
-    for (unsigned int i = 0; i < vIP.size(); i++)
-        vAddr[i] = CService(vIP[i], port);
-    return true;
+    const std::vector<CNetAddr> addresses{LookupIntern(hostname, nMaxSolutions, fAllowLookup, dns_lookup_function)};
+    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)
@@ -232,12 +209,9 @@ 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 */
@@ -689,27 +663,27 @@ bool LookupSubNet(const std::string& subnet_str, CSubNet& subnet_out)
 
     const size_t slash_pos{subnet_str.find_last_of('/')};
     const std::string str_addr{subnet_str.substr(0, slash_pos)};
-    CNetAddr addr;
+    const std::optional<CNetAddr> addr{LookupHost(str_addr, /*fAllowLookup=*/false)};
 
-    if (LookupHost(str_addr, addr, /*fAllowLookup=*/false)) {
+    if (addr.has_value()) {
         if (slash_pos != subnet_str.npos) {
             const std::string netmask_str{subnet_str.substr(slash_pos + 1)};
             uint8_t netmask;
             if (ParseUInt8(netmask_str, &netmask)) {
                 // Valid number; assume CIDR variable-length subnet masking.
-                subnet_out = CSubNet{addr, netmask};
+                subnet_out = CSubNet{addr.value(), netmask};
                 return subnet_out.IsValid();
             } else {
                 // Invalid number; try full netmask syntax. Never allow lookup for netmask.
-                CNetAddr full_netmask;
-                if (LookupHost(netmask_str, full_netmask, /*fAllowLookup=*/false)) {
-                    subnet_out = CSubNet{addr, full_netmask};
+                const std::optional<CNetAddr> full_netmask{LookupHost(netmask_str, /*fAllowLookup=*/false)};
+                if (full_netmask.has_value()) {
+                    subnet_out = CSubNet{addr.value(), full_netmask.value()};
                     return subnet_out.IsValid();
                 }
             }
         } else {
             // Single IP subnet (<ipv4>/32 or <ipv6>/128).
-            subnet_out = CSubNet{addr};
+            subnet_out = CSubNet{addr.value()};
             return subnet_out.IsValid();
         }
     }
diff --git a/src/netbase.h b/src/netbase.h
index a43f22f240..1da4f5c51d 100644
--- a/src/netbase.h
+++ b/src/netbase.h
@@ -105,24 +105,25 @@ 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)
+ * @see Lookup(const std::string&, 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 address to which the specified host
+ *          string resolved or std::nullopt if host does not resolve to an address.
+ *
+ * @see LookupHost(const std::string&, unsigned int, bool, DNSLookupFn)
  *      for additional parameter descriptions.
  */
-bool LookupHost(const std::string& name, CNetAddr& addr, bool fAllowLookup, DNSLookupFn dns_lookup_function = g_dns_lookup);
+std::optional<CNetAddr> LookupHost(const std::string& name, bool fAllowLookup, DNSLookupFn dns_lookup_function = g_dns_lookup);
 
 /**
  * Resolve a service string to its corresponding service.
@@ -132,8 +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,
@@ -141,18 +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
@@ -160,7 +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/qt/optionsdialog.cpp b/src/qt/optionsdialog.cpp
index ea624efeaa..512fce473d 100644
--- a/src/qt/optionsdialog.cpp
+++ b/src/qt/optionsdialog.cpp
@@ -406,9 +406,8 @@ void OptionsDialog::updateProxyValidationState()
 
 void OptionsDialog::updateDefaultProxyNets()
 {
-    CNetAddr ui_proxy_netaddr;
-    LookupHost(ui->proxyIp->text().toStdString(), ui_proxy_netaddr, /*fAllowLookup=*/false);
-    const CService ui_proxy{ui_proxy_netaddr, ui->proxyPort->text().toUShort()};
+    const std::optional<CNetAddr> ui_proxy_netaddr{LookupHost(ui->proxyIp->text().toStdString(), /*fAllowLookup=*/false)};
+    const CService ui_proxy{ui_proxy_netaddr.value_or(CNetAddr{}), ui->proxyPort->text().toUShort()};
 
     Proxy proxy;
     bool has_proxy;
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
index f247e6ee91..a2a46ef32f 100644
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -713,9 +713,10 @@ static RPCHelpMan setban()
         isSubnet = true;
 
     if (!isSubnet) {
-        CNetAddr resolved;
-        LookupHost(request.params[0].get_str(), resolved, false);
-        netAddr = resolved;
+        const std::optional<CNetAddr> addr{LookupHost(request.params[0].get_str(), false)};
+        if (addr.has_value()) {
+            netAddr = addr.value();
+        }
     }
     else
         LookupSubNet(request.params[0].get_str(), subNet);
@@ -943,11 +944,11 @@ static RPCHelpMan addpeeraddress()
     const bool tried{request.params[2].isNull() ? false : request.params[2].get_bool()};
 
     UniValue obj(UniValue::VOBJ);
-    CNetAddr net_addr;
+    std::optional<CNetAddr> net_addr{LookupHost(addr_string, false)};
     bool success{false};
 
-    if (LookupHost(addr_string, net_addr, false)) {
-        CService service{net_addr, port};
+    if (net_addr.has_value()) {
+        CService service{net_addr.value(), port};
         CAddress address{MaybeFlipIPv6toCJDNS(service), ServiceFlags{NODE_NETWORK | NODE_WITNESS}};
         address.nTime = Now<NodeSeconds>();
         // The source address is set equal to the address. This is equivalent to the peer
diff --git a/src/test/addrman_tests.cpp b/src/test/addrman_tests.cpp
index 54d923e4a4..328e7f81a0 100644
--- a/src/test/addrman_tests.cpp
+++ b/src/test/addrman_tests.cpp
@@ -33,16 +33,16 @@ static int32_t GetCheckRatio(const NodeContext& node_ctx)
 
 static CNetAddr ResolveIP(const std::string& ip)
 {
-    CNetAddr addr;
-    BOOST_CHECK_MESSAGE(LookupHost(ip, addr, false), strprintf("failed to resolve: %s", ip));
-    return addr;
+    const std::optional<CNetAddr> addr{LookupHost(ip, false)};
+    BOOST_CHECK_MESSAGE(addr.has_value(), strprintf("failed to resolve: %s", ip));
+    return addr.value_or(CNetAddr{});
 }
 
 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.
@@ -1004,12 +1009,12 @@ 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);
-    CNetAddr resolved;
-    BOOST_CHECK(LookupHost("252.2.2.2", resolved, false));
-    AddrInfo info = AddrInfo(addr, resolved);
+    const std::optional<CService> serv{Lookup("252.1.1.1", 7777, false)};
+    BOOST_REQUIRE(serv.has_value());
+    CAddress addr = CAddress(serv.value(), NODE_NONE);
+    std::optional<CNetAddr> resolved{LookupHost("252.2.2.2", false)};
+    BOOST_REQUIRE(resolved.has_value());
+    AddrInfo info = AddrInfo(addr, resolved.value());
     s << info;
 
     return s;
diff --git a/src/test/fuzz/netbase_dns_lookup.cpp b/src/test/fuzz/netbase_dns_lookup.cpp
index 81e216b358..dcf500acc3 100644
--- a/src/test/fuzz/netbase_dns_lookup.cpp
+++ b/src/test/fuzz/netbase_dns_lookup.cpp
@@ -29,33 +29,29 @@ 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);
     }
     {
-        CNetAddr resolved_address;
-        if (LookupHost(name, resolved_address, allow_lookup, fuzzed_dns_lookup_function)) {
-            assert(!resolved_address.IsInternal());
+        const std::optional<CNetAddr> resolved_address{LookupHost(name, allow_lookup, fuzzed_dns_lookup_function)};
+        if (resolved_address.has_value()) {
+            assert(!resolved_address.value().IsInternal());
         }
     }
     {
-        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/test/net_tests.cpp b/src/test/net_tests.cpp
index 631c213627..aa577f7b27 100644
--- a/src/test/net_tests.cpp
+++ b/src/test/net_tests.cpp
@@ -135,7 +135,7 @@ BOOST_AUTO_TEST_CASE(cnetaddr_basic)
     CNetAddr addr;
 
     // IPv4, INADDR_ANY
-    BOOST_REQUIRE(LookupHost("0.0.0.0", addr, false));
+    addr = LookupHost("0.0.0.0", false).value();
     BOOST_REQUIRE(!addr.IsValid());
     BOOST_REQUIRE(addr.IsIPv4());
 
@@ -144,7 +144,7 @@ BOOST_AUTO_TEST_CASE(cnetaddr_basic)
     BOOST_CHECK_EQUAL(addr.ToStringAddr(), "0.0.0.0");
 
     // IPv4, INADDR_NONE
-    BOOST_REQUIRE(LookupHost("255.255.255.255", addr, false));
+    addr = LookupHost("255.255.255.255", false).value();
     BOOST_REQUIRE(!addr.IsValid());
     BOOST_REQUIRE(addr.IsIPv4());
 
@@ -153,7 +153,7 @@ BOOST_AUTO_TEST_CASE(cnetaddr_basic)
     BOOST_CHECK_EQUAL(addr.ToStringAddr(), "255.255.255.255");
 
     // IPv4, casual
-    BOOST_REQUIRE(LookupHost("12.34.56.78", addr, false));
+    addr = LookupHost("12.34.56.78", false).value();
     BOOST_REQUIRE(addr.IsValid());
     BOOST_REQUIRE(addr.IsIPv4());
 
@@ -162,7 +162,7 @@ BOOST_AUTO_TEST_CASE(cnetaddr_basic)
     BOOST_CHECK_EQUAL(addr.ToStringAddr(), "12.34.56.78");
 
     // IPv6, in6addr_any
-    BOOST_REQUIRE(LookupHost("::", addr, false));
+    addr = LookupHost("::", false).value();
     BOOST_REQUIRE(!addr.IsValid());
     BOOST_REQUIRE(addr.IsIPv6());
 
@@ -171,7 +171,7 @@ BOOST_AUTO_TEST_CASE(cnetaddr_basic)
     BOOST_CHECK_EQUAL(addr.ToStringAddr(), "::");
 
     // IPv6, casual
-    BOOST_REQUIRE(LookupHost("1122:3344:5566:7788:9900:aabb:ccdd:eeff", addr, false));
+    addr = LookupHost("1122:3344:5566:7788:9900:aabb:ccdd:eeff", false).value();
     BOOST_REQUIRE(addr.IsValid());
     BOOST_REQUIRE(addr.IsIPv6());
 
@@ -186,14 +186,14 @@ BOOST_AUTO_TEST_CASE(cnetaddr_basic)
     // id of "32", return the address as "fe80::1%32".
     const std::string link_local{"fe80::1"};
     const std::string scoped_addr{link_local + "%32"};
-    BOOST_REQUIRE(LookupHost(scoped_addr, addr, false));
+    addr = LookupHost(scoped_addr, false).value();
     BOOST_REQUIRE(addr.IsValid());
     BOOST_REQUIRE(addr.IsIPv6());
     BOOST_CHECK(!addr.IsBindAny());
     BOOST_CHECK_EQUAL(addr.ToStringAddr(), scoped_addr);
 
     // Test that the delimiter "%" and default zone id of 0 can be omitted for the default scope.
-    BOOST_REQUIRE(LookupHost(link_local + "%0", addr, false));
+    addr = LookupHost(link_local + "%0", false).value();
     BOOST_REQUIRE(addr.IsValid());
     BOOST_REQUIRE(addr.IsIPv6());
     BOOST_CHECK(!addr.IsBindAny());
@@ -318,10 +318,9 @@ BOOST_AUTO_TEST_CASE(cnetaddr_tostring_canonical_ipv6)
         {"2001:db8:aaaa:bbbb:cccc:dddd:eeee:AaAa", "2001:db8:aaaa:bbbb:cccc:dddd:eeee:aaaa"},
     };
     for (const auto& [input_address, expected_canonical_representation_output] : canonical_representations_ipv6) {
-        CNetAddr net_addr;
-        BOOST_REQUIRE(LookupHost(input_address, net_addr, false));
-        BOOST_REQUIRE(net_addr.IsIPv6());
-        BOOST_CHECK_EQUAL(net_addr.ToStringAddr(), expected_canonical_representation_output);
+        const std::optional<CNetAddr> net_addr{LookupHost(input_address, false)};
+        BOOST_REQUIRE(net_addr.value().IsIPv6());
+        BOOST_CHECK_EQUAL(net_addr.value().ToStringAddr(), expected_canonical_representation_output);
     }
 }
 
@@ -334,12 +333,12 @@ BOOST_AUTO_TEST_CASE(cnetaddr_serialize_v1)
     BOOST_CHECK_EQUAL(HexStr(s), "00000000000000000000000000000000");
     s.clear();
 
-    BOOST_REQUIRE(LookupHost("1.2.3.4", addr, false));
+    addr = LookupHost("1.2.3.4", false).value();
     s << addr;
     BOOST_CHECK_EQUAL(HexStr(s), "00000000000000000000ffff01020304");
     s.clear();
 
-    BOOST_REQUIRE(LookupHost("1a1b:2a2b:3a3b:4a4b:5a5b:6a6b:7a7b:8a8b", addr, false));
+    addr = LookupHost("1a1b:2a2b:3a3b:4a4b:5a5b:6a6b:7a7b:8a8b", false).value();
     s << addr;
     BOOST_CHECK_EQUAL(HexStr(s), "1a1b2a2b3a3b4a4b5a5b6a6b7a7b8a8b");
     s.clear();
@@ -370,12 +369,12 @@ BOOST_AUTO_TEST_CASE(cnetaddr_serialize_v2)
     BOOST_CHECK_EQUAL(HexStr(s), "021000000000000000000000000000000000");
     s.clear();
 
-    BOOST_REQUIRE(LookupHost("1.2.3.4", addr, false));
+    addr = LookupHost("1.2.3.4", false).value();
     s << addr;
     BOOST_CHECK_EQUAL(HexStr(s), "010401020304");
     s.clear();
 
-    BOOST_REQUIRE(LookupHost("1a1b:2a2b:3a3b:4a4b:5a5b:6a6b:7a7b:8a8b", addr, false));
+    addr = LookupHost("1a1b:2a2b:3a3b:4a4b:5a5b:6a6b:7a7b:8a8b", false).value();
     s << addr;
     BOOST_CHECK_EQUAL(HexStr(s), "02101a1b2a2b3a3b4a4b5a5b6a6b7a7b8a8b");
     s.clear();
diff --git a/src/test/netbase_tests.cpp b/src/test/netbase_tests.cpp
index 7e91819ddc..05953bfd10 100644
--- a/src/test/netbase_tests.cpp
+++ b/src/test/netbase_tests.cpp
@@ -24,9 +24,7 @@ BOOST_FIXTURE_TEST_SUITE(netbase_tests, BasicTestingSetup)
 
 static CNetAddr ResolveIP(const std::string& ip)
 {
-    CNetAddr addr;
-    LookupHost(ip, addr, false);
-    return addr;
+    return LookupHost(ip, false).value_or(CNetAddr{});
 }
 
 static CSubNet ResolveSubNet(const std::string& subnet)
@@ -477,11 +475,10 @@ BOOST_AUTO_TEST_CASE(netpermissions_test)
 
 BOOST_AUTO_TEST_CASE(netbase_dont_resolve_strings_with_embedded_nul_characters)
 {
-    CNetAddr addr;
-    BOOST_CHECK(LookupHost("127.0.0.1"s, addr, false));
-    BOOST_CHECK(!LookupHost("127.0.0.1\0"s, addr, false));
-    BOOST_CHECK(!LookupHost("127.0.0.1\0example.com"s, addr, false));
-    BOOST_CHECK(!LookupHost("127.0.0.1\0example.com\0"s, addr, false));
+    BOOST_CHECK(LookupHost("127.0.0.1"s, false).has_value());
+    BOOST_CHECK(!LookupHost("127.0.0.1\0"s, false).has_value());
+    BOOST_CHECK(!LookupHost("127.0.0.1\0example.com"s, false).has_value());
+    BOOST_CHECK(!LookupHost("127.0.0.1\0example.com\0"s, false).has_value());
     CSubNet ret;
     BOOST_CHECK(LookupSubNet("1.2.3.0/24"s, ret));
     BOOST_CHECK(!LookupSubNet("1.2.3.0/24\0"s, ret));
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;
     }
diff --git a/src/zmq/zmqpublishnotifier.cpp b/src/zmq/zmqpublishnotifier.cpp
index 21aa44c309..1241431523 100644
--- a/src/zmq/zmqpublishnotifier.cpp
+++ b/src/zmq/zmqpublishnotifier.cpp
@@ -97,9 +97,8 @@ static bool IsZMQAddressIPV6(const std::string &zmq_address)
     const size_t colon_index = zmq_address.rfind(':');
     if (tcp_index == 0 && colon_index != std::string::npos) {
         const std::string ip = zmq_address.substr(tcp_prefix.length(), colon_index - tcp_prefix.length());
-        CNetAddr addr;
-        LookupHost(ip, addr, false);
-        if (addr.IsIPv6()) return true;
+        const std::optional<CNetAddr> addr{LookupHost(ip, false)};
+        if (addr.has_value() && addr.value().IsIPv6()) return true;
     }
     return false;
 }