netbase: extend Proxy class to wrap UNIX socket as well as TCP

src/net.cpp

@@ -483,7 +483,7 @@ CNode* CConnman::ConnectNode(CAddress addrConnect, const char *pszDest, bool fCo
                 addr_bind = CAddress{conn.me, NODE_NONE};
             }
         } else if (use_proxy) {
-            LogPrintLevel(BCLog::PROXY, BCLog::Level::Debug, "Using proxy: %s to connect to %s:%s\n", proxy.proxy.ToStringAddrPort(), addrConnect.ToStringAddr(), addrConnect.GetPort());
+            LogPrintLevel(BCLog::PROXY, BCLog::Level::Debug, "Using proxy: %s to connect to %s:%s\n", proxy.ToString(), addrConnect.ToStringAddr(), addrConnect.GetPort());
             sock = ConnectThroughProxy(proxy, addrConnect.ToStringAddr(), addrConnect.GetPort(), proxyConnectionFailed);
         } else {
             // no proxy needed (none set for target network)

src/netbase.cpp

@@ -216,6 +216,24 @@ CService LookupNumeric(const std::string& name, uint16_t portDefault, DNSLookupF
     return Lookup(name, portDefault, /*fAllowLookup=*/false, dns_lookup_function).value_or(CService{});
 }
 
+bool IsUnixSocketPath(const std::string& name)
+{
+#if HAVE_SOCKADDR_UN
+    if (name.find(ADDR_PREFIX_UNIX) != 0) return false;
+
+    // Split off "unix:" prefix
+    std::string str{name.substr(ADDR_PREFIX_UNIX.length())};
+
+    // Path size limit is platform-dependent
+    // see https://manpages.ubuntu.com/manpages/xenial/en/man7/unix.7.html
+    if (str.size() + 1 > sizeof(((sockaddr_un*)nullptr)->sun_path)) return false;
+
+    return true;
+#else
+    return false;
+#endif
+}
+
 /** SOCKS version */
 enum SOCKSVersion: uint8_t {
     SOCKS4 = 0x04,

src/netbase.h

@@ -27,6 +27,9 @@ static const int DEFAULT_CONNECT_TIMEOUT = 5000;
 //! -dns default
 static const int DEFAULT_NAME_LOOKUP = true;
 
+/** Prefix for unix domain socket addresses (which are local filesystem paths) */
+const std::string ADDR_PREFIX_UNIX = "unix:";
+
 enum class ConnectionDirection {
     None = 0,
     In = (1U << 0),
@@ -43,16 +46,44 @@ static inline bool operator&(ConnectionDirection a, ConnectionDirection b) {
     return (underlying(a) & underlying(b));
 }
 
+/**
+ * Check if a string is a valid UNIX domain socket path
+ *
+ * @param      name     The string provided by the user representing a local path
+ *
+ * @returns Whether the string has proper format, length, and points to an existing file path
+ */
+bool IsUnixSocketPath(const std::string& name);
+
 class Proxy
 {
 public:
-    Proxy(): randomize_credentials(false) {}
-    explicit Proxy(const CService &_proxy, bool _randomize_credentials=false): proxy(_proxy), randomize_credentials(_randomize_credentials) {}
-
-    bool IsValid() const { return proxy.IsValid(); }
+    Proxy(): m_is_unix_socket(false), randomize_credentials(false) {}
+    explicit Proxy(const CService &_proxy, bool _randomize_credentials=false): proxy(_proxy), m_is_unix_socket(false), randomize_credentials(_randomize_credentials) {}
+    explicit Proxy(const std::string path, bool _randomize_credentials=false): m_unix_socket_path(path), m_is_unix_socket(true), randomize_credentials(_randomize_credentials) {}
 
     CService proxy;
+    std::string m_unix_socket_path;
+    bool m_is_unix_socket;
     bool randomize_credentials;
+
+    bool IsValid() const
+    {
+        if (m_is_unix_socket) return IsUnixSocketPath(m_unix_socket_path);
+        return proxy.IsValid();
+    }
+
+    sa_family_t GetFamily() const
+    {
+        if (m_is_unix_socket) return AF_UNIX;
+        return proxy.GetSAFamily();
+    }
+
+    std::string ToString() const
+    {
+        if (m_is_unix_socket) return m_unix_socket_path;
+        return proxy.ToStringAddrPort();
+    }
 };
 
 /** Credentials for proxy authentication */

src/rpc/net.cpp

@@ -607,7 +607,7 @@ static UniValue GetNetworksInfo()
         obj.pushKV("name", GetNetworkName(network));
         obj.pushKV("limited", !g_reachable_nets.Contains(network));
         obj.pushKV("reachable", g_reachable_nets.Contains(network));
-        obj.pushKV("proxy", proxy.IsValid() ? proxy.proxy.ToStringAddrPort() : std::string());
+        obj.pushKV("proxy", proxy.IsValid() ? proxy.ToString() : std::string());
         obj.pushKV("proxy_randomize_credentials", proxy.randomize_credentials);
         networks.push_back(obj);
     }