nall: make gdb server accept only one connection at a time. (#1369)

This closes the socket server after each successful connection so that new connections are immediately refused. Before, given that the server socket was always in listen mode, one additional connection could always be estabilished at the TCP level, even though the server wouldn't accept it right away.
ares-emulator · Jan 22, 2024 · e2caf17 · e2caf17
1 parent 322c99c
commit e2caf17
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Showing 2 changed files with 79 additions and 66 deletions.
diff --git a/nall/tcptext/tcp-socket.cpp b/nall/tcptext/tcp-socket.cpp
@@ -70,92 +70,105 @@ NALL_HEADER_INLINE auto Socket::open(u32 port, bool useIPv4) -> bool {
   auto threadServer = std::thread([this, port, useIPv4]() {
     serverRunning = true;
 
-    fdServer = socket(useIPv4 ? AF_INET : AF_INET6, SOCK_STREAM, 0);  
-    if(fdServer < 0) {
-      serverRunning = false;
-      return;
-    }
+    while (!stopServer) {
+      fdServer = socket(useIPv4 ? AF_INET : AF_INET6, SOCK_STREAM, 0);  
+      if(fdServer < 0)
+        break;
+
+      {
+        s32 valueOn = 1;
+        #if defined(SO_NOSIGPIPE)  //BSD, OSX
+          setsockopt(fdServer, SOL_SOCKET, SO_NOSIGPIPE, &valueOn, sizeof(s32));
+        #endif
 
-    {
-      s32 valueOn = 1;
-      #if defined(SO_NOSIGPIPE)  //BSD, OSX
-        setsockopt(fdServer, SOL_SOCKET, SO_NOSIGPIPE, &valueOn, sizeof(s32));
-      #endif
+        #if defined(SO_REUSEADDR)  //BSD, Linux, OSX
+          setsockopt(fdServer, SOL_SOCKET, SO_REUSEADDR, &valueOn, sizeof(s32));
+        #endif
 
-      #if defined(SO_REUSEADDR)  //BSD, Linux, OSX
-        setsockopt(fdServer, SOL_SOCKET, SO_REUSEADDR, &valueOn, sizeof(s32));
-      #endif
+        #if defined(SO_REUSEPORT)  //BSD, OSX
+          setsockopt(fdServer, SOL_SOCKET, SO_REUSEPORT, &valueOn, sizeof(s32));
+        #endif
 
-      #if defined(SO_REUSEPORT)  //BSD, OSX
-        setsockopt(fdServer, SOL_SOCKET, SO_REUSEPORT, &valueOn, sizeof(s32));
-      #endif
+        #if defined(TCP_NODELAY)
+          setsockopt(fdServer, IPPROTO_TCP, TCP_NODELAY, &valueOn, sizeof(s32));
+        #endif
 
-      #if defined(TCP_NODELAY)
-        setsockopt(fdServer, IPPROTO_TCP, TCP_NODELAY, &valueOn, sizeof(s32));
-      #endif
+        if(!socketSetBlockingMode(fdServer, true)) {
+          print("TCP: failed to set to blocking mode!\n");
+        }
 
-      if(!socketSetBlockingMode(fdServer, true)) {
-        print("TCP: failed to set to blocking mode!\n");
+        #if defined(SO_RCVTIMEO)
+          #if defined(PLATFORM_WINDOWS)
+            DWORD rcvTimeMs = 1000 * RECEIVE_TIMEOUT_SEC;
+            setsockopt(fdServer, SOL_SOCKET, SO_RCVTIMEO, &rcvTimeMs, sizeof(rcvTimeMs));
+          #else
+            struct timeval rcvtimeo;
+            rcvtimeo.tv_sec  = RECEIVE_TIMEOUT_SEC;
+            rcvtimeo.tv_usec = 0;
+            setsockopt(fdServer, SOL_SOCKET, SO_RCVTIMEO, &rcvtimeo, sizeof(rcvtimeo));
+          #endif
+        #endif
       }
 
-      #if defined(SO_RCVTIMEO)
-        #if defined(PLATFORM_WINDOWS)
-          DWORD rcvTimeMs = 1000 * RECEIVE_TIMEOUT_SEC;
-          setsockopt(fdServer, SOL_SOCKET, SO_RCVTIMEO, &rcvTimeMs, sizeof(rcvTimeMs));
-        #else
-          struct timeval rcvtimeo;
-          rcvtimeo.tv_sec  = RECEIVE_TIMEOUT_SEC;
-          rcvtimeo.tv_usec = 0;
-          setsockopt(fdServer, SOL_SOCKET, SO_RCVTIMEO, &rcvtimeo, sizeof(rcvtimeo));
-        #endif
-      #endif
-    }
+      s32 bindRes;
+      if(useIPv4) {
+        sockaddr_in serverAddrV4{};
+        serverAddrV4.sin_family = AF_INET;
+        serverAddrV4.sin_addr.s_addr = htonl(INADDR_ANY);
+        serverAddrV4.sin_port = htons(port);
 
-    s32 bindRes;
-    if(useIPv4) {
-      sockaddr_in serverAddrV4{};
-      serverAddrV4.sin_family = AF_INET;
-      serverAddrV4.sin_addr.s_addr = htonl(INADDR_ANY);
-      serverAddrV4.sin_port = htons(port);
-
-      bindRes = ::bind(fdServer, (sockaddr*)&serverAddrV4, sizeof(serverAddrV4)) < 0;
-    } else {
-      sockaddr_in6 serverAddrV6{};
-      serverAddrV6.sin6_family = AF_INET6;
-      serverAddrV6.sin6_addr = in6addr_loopback;
-      serverAddrV6.sin6_port = htons(port);
-
-      bindRes = ::bind(fdServer, (sockaddr*)&serverAddrV6, sizeof(serverAddrV6)) < 0;
-    }
+        bindRes = ::bind(fdServer, (sockaddr*)&serverAddrV4, sizeof(serverAddrV4)) < 0;
+      } else {
+        sockaddr_in6 serverAddrV6{};
+        serverAddrV6.sin6_family = AF_INET6;
+        serverAddrV6.sin6_addr = in6addr_loopback;
+        serverAddrV6.sin6_port = htons(port);
 
-    if(bindRes < 0 || listen(fdServer, 1) < 0) {
+        bindRes = ::bind(fdServer, (sockaddr*)&serverAddrV6, sizeof(serverAddrV6)) < 0;
+      }
+
+      if(bindRes < 0 || listen(fdServer, 1) < 0) {
         printf("error binding socket on port %d! (%s)\n", port, strerror(errno));
-        stopServer = true;
-    }
+        break;
+      }
 
-    while(!stopServer) 
-    {
       // scan for new connections
-      if(fdClient < 0) {
+      while(fdClient < 0) {
         fdClient = ::accept(fdServer, nullptr, nullptr);
+        if(fdClient < 0) {
+          if(errno != EAGAIN) {
+            if(!stopServer)
+              printf("error accepting connection! (%s)\n", strerror(errno));
+            break;
+          }
+          std::this_thread::sleep_for(std::chrono::milliseconds(CLIENT_SLEEP_MS));
+        }
       }
-
-      // Kick client if we need to
-      if(fdClient >= 0 && wantKickClient) {
-        socketClose(fdClient);
-        fdClient = -1;
-        wantKickClient = false;
-        onDisconnect();
+      if (fdClient < 0) {
+        break;
       }
 
-      std::this_thread::sleep_for(std::chrono::milliseconds(CLIENT_SLEEP_MS));
+      // close the server socket, we only want one client
+      socketClose(fdServer);
+      fdServer = -1;
+
+      while (!stopServer && fdClient >= 0) {
+        // Kick client if we need to
+        if(wantKickClient) {
+          socketClose(fdClient);
+          fdClient = -1;
+          wantKickClient = false;
+          onDisconnect();
+          break;
+        }
+
+        std::this_thread::sleep_for(std::chrono::milliseconds(CLIENT_SLEEP_MS));
+      }
     }
 
     printf("Stopping TCP-server...\n");
 
     socketClose(fdClient);
-    socketClose(fdServer);
-    fdServer = -1;
     fdClient = -1;
 
     wantKickClient = false;

diff --git a/nall/tcptext/tcp-socket.hpp b/nall/tcptext/tcp-socket.hpp
@@ -27,7 +27,7 @@ class Socket {
 
     auto disconnectClient() -> void;
 
-    auto isStarted() const -> bool { return fdServer >= 0; }
+    auto isStarted() const -> bool { return serverRunning; }
     auto hasClient() const -> bool { return fdClient >= 0; }
 
     auto getURL(u32 port, bool useIPv4) const -> string;