Merge branch 'feature/KASM-4034_unix_sockets' into 'master'

Add support for relaying unix sockets

Closes KASM-4034

See merge request kasm-technologies/internal/KasmVNC!90

common/rfb/SDesktop.h

@@ -88,6 +88,9 @@ namespace rfb {
 
     virtual void clearLocalClipboards() {}
 
+    virtual void receivedUnixRelayData(const char name[], const unsigned char *buf,
+                                       const unsigned len) {}
+
   protected:
     virtual ~SDesktop() {}
   };

common/rfb/SMsgHandler.h

@@ -98,6 +98,9 @@ namespace rfb {
     virtual void udpUpgrade(const char *resp) = 0;
     virtual void udpDowngrade(const bool) = 0;
 
+    virtual void subscribeUnixRelay(const char *name) = 0;
+    virtual void unixRelay(const char *name, const rdr::U8 *buf, const unsigned len) = 0;
+
     ConnParams cp;
   };
 }

common/rfb/SMsgReader.cxx

@@ -100,6 +100,12 @@ void SMsgReader::readMsg()
   case msgTypeUpgradeToUdp:
     readUpgradeToUdp();
     break;
+  case msgTypeSubscribeUnixRelay:
+    readSubscribeUnixRelay();
+    break;
+  case msgTypeUnixRelay:
+    readUnixRelay();
+    break;
   default:
     fprintf(stderr, "unknown message type %d\n", msgType);
     throw Exception("unknown message type");
@@ -357,3 +363,42 @@ void SMsgReader::readUpgradeToUdp()
 
   handler->udpUpgrade(resp);
 }
+
+void SMsgReader::readSubscribeUnixRelay()
+{
+  const rdr::U8 namelen = is->readU8();
+  char name[64];
+  if (namelen >= sizeof(name)) {
+    vlog.error("Ignoring subscribe with too large name");
+    is->skip(namelen);
+    return;
+  }
+  is->readBytes(name, namelen);
+  name[namelen] = '\0';
+
+  handler->subscribeUnixRelay(name);
+}
+
+void SMsgReader::readUnixRelay()
+{
+  const rdr::U8 namelen = is->readU8();
+  char name[64];
+  if (namelen >= sizeof(name)) {
+    vlog.error("Ignoring relay packet with too large name");
+    is->skip(namelen);
+    return;
+  }
+  is->readBytes(name, namelen);
+  name[namelen] = '\0';
+
+  const rdr::U32 len = is->readU32();
+  rdr::U8 buf[1024 * 1024];
+  if (len >= sizeof(buf)) {
+    vlog.error("Ignoring relay packet with too large data");
+    is->skip(len);
+    return ;
+  }
+  is->readBytes(buf, len);
+
+  handler->unixRelay(name, buf, len);
+}

common/rfb/SMsgReader.h

@@ -65,6 +65,9 @@ namespace rfb {
 
     void readUpgradeToUdp();
 
+    void readSubscribeUnixRelay();
+    void readUnixRelay();
+
     SMsgHandler* handler;
     rdr::InStream* is;
   };

common/rfb/SMsgWriter.cxx

@@ -749,3 +749,29 @@ void SMsgWriter::writeUdpUpgrade(const char *resp)
 
   endMsg();
 }
+
+void SMsgWriter::writeSubscribeUnixRelay(const bool success, const char *msg)
+{
+  startMsg(msgTypeSubscribeUnixRelay);
+
+  const rdr::U8 len = strlen(msg);
+  os->writeU8(success);
+  os->writeU8(len);
+  os->writeBytes(msg, len);
+
+  endMsg();
+}
+
+void SMsgWriter::writeUnixRelay(const char *name, const rdr::U8 *buf, const unsigned len)
+{
+  startMsg(msgTypeUnixRelay);
+
+  const rdr::U8 namelen = strlen(name);
+  os->writeU8(namelen);
+  os->writeBytes(name, namelen);
+
+  os->writeU32(len);
+  os->writeBytes(buf, len);
+
+  endMsg();
+}

common/rfb/SMsgWriter.h

@@ -129,6 +129,9 @@ namespace rfb {
 
     void writeUdpUpgrade(const char *resp);
 
+    void writeSubscribeUnixRelay(const bool success, const char *msg);
+    void writeUnixRelay(const char *name, const rdr::U8 *buf, const unsigned len);
+
   protected:
     void startMsg(int type);
     void endMsg();

common/rfb/VNCSConnectionST.cxx

@@ -51,6 +51,8 @@ static Cursor emptyCursor(0, 0, Point(0, 0), NULL);
 
 extern rfb::BoolParameter disablebasicauth;
 
+extern "C" char unixrelaynames[MAX_UNIX_RELAYS][MAX_UNIX_RELAY_NAME_LEN];
+
 VNCSConnectionST::VNCSConnectionST(VNCServerST* server_, network::Socket *s,
                                    bool reverse)
   : upgradingToUdp(false), sock(s), reverseConnection(reverse),
@@ -73,6 +75,10 @@ VNCSConnectionST::VNCSConnectionST(VNCServerST* server_, network::Socket *s,
   memset(bstats_total, 0, sizeof(bstats_total));
   gettimeofday(&connStart, NULL);
 
+  unsigned i;
+  for (i = 0; i < MAX_UNIX_RELAYS; i++)
+    unixRelaySubscriptions[i][0] = '\0';
+
   // Check their permissions, if applicable
   kasmpasswdpath[0] = '\0';
   wordexp_t wexp;
@@ -1789,3 +1795,54 @@ void VNCSConnectionST::udpDowngrade(const bool byServer)
   vlog.info("Client %s downgrading from udp by %s", sock->getPeerAddress(),
             byServer ? "the server" : "its own request");
 }
+
+void VNCSConnectionST::subscribeUnixRelay(const char *name)
+{
+  bool read, write, owner;
+  if (!getPerms(read, write, owner) || !write) {
+    // Need write permissions to subscribe
+    writer()->writeSubscribeUnixRelay(false, "No permissions");
+    vlog.info("Client tried to subscribe to unix channel %s without permissions", name);
+    return;
+  }
+
+  unsigned i;
+  bool found = false;
+  for (i = 0; i < MAX_UNIX_RELAYS; i++) {
+    if (!strcmp(name, unixrelaynames[i])) {
+      found = true;
+      break;
+    }
+  }
+
+  if (!found) {
+    writer()->writeSubscribeUnixRelay(false, "No such unix channel");
+    vlog.info("Client tried to subscribe to nonexistent unix channel %s", name);
+    return;
+  }
+
+  writer()->writeSubscribeUnixRelay(true, "Ok");
+  for (i = 0; i < MAX_UNIX_RELAYS; i++) {
+    if (!unixRelaySubscriptions[i][0]) {
+      strcpy(unixRelaySubscriptions[i], name);
+      break;
+    }
+  }
+}
+
+void VNCSConnectionST::unixRelay(const char *name, const rdr::U8 *buf, const unsigned len)
+{
+  unsigned i;
+  for (i = 0; i < MAX_UNIX_RELAYS; i++) {
+    if (!strcmp(unixRelaySubscriptions[i], name)) {
+      server->desktop->receivedUnixRelayData(name, buf, len);
+      return;
+    }
+  }
+}
+
+void VNCSConnectionST::sendUnixRelayData(const char name[], const unsigned char *buf,
+                                         const unsigned len)
+{
+  writer()->writeUnixRelay(name, buf, len);
+}

common/rfb/VNCSConnectionST.h

@@ -33,6 +33,7 @@
 #include <rfb/EncodeManager.h>
 #include <rfb/SConnection.h>
 #include <rfb/Timer.h>
+#include <rfb/unixRelayLimits.h>
 
 namespace rfb {
   class VNCServerST;
@@ -200,6 +201,18 @@ namespace rfb {
 
     bool upgradingToUdp;
 
+    bool isSubscribedToUnixRelay(const char *name) const {
+      unsigned i;
+      for (i = 0; i < MAX_UNIX_RELAYS; i++) {
+        if (!strcmp(unixRelaySubscriptions[i], name))
+          return true;
+      }
+      return false;
+    }
+
+    virtual void sendUnixRelayData(const char name[], const unsigned char *buf,
+                                   const unsigned len);
+
   private:
     // SConnection callbacks
 
@@ -222,6 +235,8 @@ namespace rfb {
     virtual void handleClipboardAnnounce(bool available);
     virtual void handleClipboardAnnounceBinary(const unsigned num, const char mimes[][32]);
     virtual void udpUpgrade(const char *resp);
+    virtual void subscribeUnixRelay(const char *name);
+    virtual void unixRelay(const char *name, const rdr::U8 *buf, const unsigned len);
     virtual void supportsLocalCursor();
     virtual void supportsFence();
     virtual void supportsContinuousUpdates();
@@ -324,6 +339,8 @@ namespace rfb {
 
     bool frameTracking;
     uint32_t udpFramesSinceFull;
+
+    char unixRelaySubscriptions[MAX_UNIX_RELAYS][MAX_UNIX_RELAY_NAME_LEN];
     bool complainedAboutNoViewRights;
   };
 }

common/rfb/VNCServerST.cxx

@@ -1253,3 +1253,15 @@ void VNCServerST::refreshClients()
     (*i)->add_changed_all();
   }
 }
+
+void VNCServerST::sendUnixRelayData(const char name[],
+                                    const unsigned char *buf, const unsigned len)
+{
+  // For each client subscribed to this channel, send the data to them
+  std::list<VNCSConnectionST*>::iterator i;
+  for (i = clients.begin(); i != clients.end(); i++) {
+    if ((*i)->isSubscribedToUnixRelay(name)) {
+      (*i)->sendUnixRelayData(name, buf, len);
+    }
+  }
+}

common/rfb/VNCServerST.h

@@ -198,6 +198,7 @@ namespace rfb {
                                        const char mimes[][32]);
 
     void refreshClients();
+    void sendUnixRelayData(const char name[], const unsigned char *buf, const unsigned len);
 
   protected:
 

common/rfb/msgTypes.h

@@ -33,6 +33,8 @@ namespace rfb {
   const int msgTypeRequestFrameStats = 179;
   const int msgTypeBinaryClipboard = 180;
   const int msgTypeUpgradeToUdp = 181;
+  const int msgTypeSubscribeUnixRelay = 182;
+  const int msgTypeUnixRelay = 183;
 
   const int msgTypeServerFence = 248;
 
@@ -54,6 +56,8 @@ namespace rfb {
   // same as the other direction
   //const int msgTypeBinaryClipboard = 180;
   //const int msgTypeUpgradeToUdp = 181;
+  //const int msgTypeSubscribeUnixRelay = 182;
+  //const int msgTypeUnixRelay = 183;
 
   const int msgTypeClientFence = 248;
 

common/rfb/unixRelayLimits.h

@@ -0,0 +1,7 @@
+#ifndef UNIX_RELAY_LIMITS_H
+#define UNIX_RELAY_LIMITS_H
+
+#define MAX_UNIX_RELAYS 4
+#define MAX_UNIX_RELAY_NAME_LEN 64
+
+#endif

unix/xserver/hw/vnc/XserverDesktop.cc

@@ -29,6 +29,8 @@
 #include <pwd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/un.h>
 #include <fcntl.h>
 #include <sys/utsname.h>
 
@@ -51,6 +53,7 @@ extern "C" {
 void vncSetGlueContext(int screenIndex);
 
 extern int wakeuppipe[2];
+extern struct sockaddr_un unixrelayclients[MAX_UNIX_RELAYS];
 }
 
 using namespace rfb;
@@ -323,6 +326,26 @@ void XserverDesktop::handleSocketEvent(int fd, bool read, bool write)
         return;
       }
 
+      unsigned i;
+      for (i = 0; i < MAX_UNIX_RELAYS; i++) {
+        if (unixrelays[i] == -1)
+            break;
+        if (fd == unixrelays[i]) {
+            do {
+                struct sockaddr_un client;
+                socklen_t addrlen = sizeof(struct sockaddr_un);
+                const ssize_t len = recvfrom(unixrelays[i], unixbuf, sizeof(unixbuf),
+                                         MSG_DONTWAIT,
+                                         (struct sockaddr *) &client, &addrlen);
+                if (len <= 0)
+                    break;
+                memcpy(&unixrelayclients[i], &client, addrlen);
+                server->sendUnixRelayData(unixrelaynames[i], unixbuf, len);
+            } while (1);
+            return;
+        }
+      }
+
       if (handleListenerEvent(fd, &listeners, server))
         return;
     }
@@ -557,3 +580,21 @@ bool XserverDesktop::handleTimeout(Timer* t)
 
   return false;
 }
+
+void XserverDesktop::receivedUnixRelayData(const char name[], const unsigned char *buf,
+                                           const unsigned len)
+{
+  unsigned i;
+  for (i = 0; i < MAX_UNIX_RELAYS; i++) {
+    if (unixrelays[i] == -1)
+      break;
+    if (strcmp(name, unixrelaynames[i]))
+      continue;
+
+    if (sendto(unixrelays[i], buf, len, 0,
+               (struct sockaddr *) &unixrelayclients[i], sizeof(struct sockaddr_un)) == -1)
+      vlog.error("Error writing unix relay data to %s", name);
+
+    break;
+  }
+}

unix/xserver/hw/vnc/XserverDesktop.h

@@ -110,6 +110,9 @@ public:
                                                         const char* userName,
                                                         char** reason);
 
+  virtual void receivedUnixRelayData(const char name[], const unsigned char *buf,
+                                     const unsigned len);
+
 protected:
   bool handleListenerEvent(int fd,
                            std::list<network::SocketListener*>* sockets,
@@ -138,5 +141,7 @@ private:
   rfb::Point oldCursorPos;
 
   bool resizing;
+
+  uint8_t unixbuf[1024 * 1024];
 };
 #endif

unix/xserver/hw/vnc/Xvnc.man

@@ -89,6 +89,11 @@ Use IPv4 for incoming and outgoing connections. Default is on.
 Use IPv6 for incoming and outgoing connections. Default is on.
 .
 .TP
+.B \-UnixRelay \fIname:path\fP
+Create a local named unix socket, for relaying data. May be given multiple times.
+Example: -UnixRelay audio:/tmp/audiosock
+.
+.TP
 .B \-rfbunixpath \fIpath\fP
 Specifies the path of a Unix domain socket on which Xvnc listens for
 connections from viewers, instead of listening on a TCP port.

unix/xserver/hw/vnc/vncExtInit.cc

@@ -241,6 +241,14 @@ void vncExtensionInit(void)
       fcntl(wakeuppipe[0], F_SETFL, flags | O_NONBLOCK);
       vncSetNotifyFd(wakeuppipe[0], 0, true, false);
 
+      unsigned i;
+      for (i = 0; i < MAX_UNIX_RELAYS; i++) {
+          if (unixrelays[i] == -1)
+              break;
+          vncSetNotifyFd(unixrelays[i], 0, true, false);
+          vlog.info("Listening to unix relay socket %s", unixrelaynames[i]);
+      }
+
       initialised = true;
     }
 

unix/xserver/hw/vnc/vncExtInit.h

@@ -23,6 +23,8 @@
 #include <stddef.h>
 #include <sys/select.h>
 
+#include <rfb/unixRelayLimits.h>
+
 // Only from C++
 #ifdef __cplusplus
 namespace rfb { class StringParameter; };
@@ -106,6 +108,9 @@ void vncRefreshScreenLayout(int scrIdx);
 
 int vncOverrideParam(const char *nameAndValue);
 
+extern int unixrelays[MAX_UNIX_RELAYS];
+extern char unixrelaynames[MAX_UNIX_RELAYS][MAX_UNIX_RELAY_NAME_LEN];
+
 #ifdef __cplusplus
 }
 #endif

unix/xserver/hw/vnc/xvnc.c

@@ -61,8 +61,11 @@ from the X Consortium.
 #include "input.h"
 #include "mipointer.h"
 #include "micmap.h"
+#include <sys/socket.h>
+#include <sys/un.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <unistd.h>
 #include <errno.h>
 #ifndef WIN32
 #include <sys/param.h>
@@ -163,6 +166,73 @@ static char displayNumStr[16];
 
 static int vncVerbose = DEFAULT_LOG_VERBOSITY;
 
+int unixrelays[MAX_UNIX_RELAYS];
+char unixrelaynames[MAX_UNIX_RELAYS][MAX_UNIX_RELAY_NAME_LEN];
+struct sockaddr_un unixrelayclients[MAX_UNIX_RELAYS];
+
+static unsigned addrelay(const char * const arg)
+{
+    const char *ptr = strchr(arg, ':');
+    if (!ptr) {
+        ErrorF("Invalid unixrelay\n");
+        return 1;
+    }
+
+    const unsigned namelen = ptr - arg;
+    if (namelen >= MAX_UNIX_RELAY_NAME_LEN) {
+        ErrorF("Unix relay name too long\n");
+        return 1;
+    }
+
+    unsigned i;
+    unsigned char found = 0;
+    for (i = 0; i < MAX_UNIX_RELAYS; i++) {
+        if (unixrelays[i] == -1) {
+            found = 1;
+            break;
+        }
+    }
+    if (!found) {
+        ErrorF("Too many unix relays\n");
+        return 1;
+    }
+
+    memcpy(unixrelaynames[i], arg, namelen);
+    unixrelaynames[i][namelen] = '\0';
+
+    unixrelays[i] = socket(AF_UNIX, SOCK_DGRAM, 0);
+    if (unixrelays[i] < 0) {
+        ErrorF("Failed to create unix sock\n");
+        return 1;
+    }
+
+    ptr++;
+    struct sockaddr_un sa;
+    if (strlen(ptr) >= sizeof(sa.sun_path)) {
+        ErrorF("Unix relay path too long\n");
+        return 1;
+    }
+
+    sa.sun_family = AF_UNIX;
+    strcpy(sa.sun_path, ptr);
+
+    // SO_REUSEADDR doesn't exist for unix sockets, if the socket exists
+    // (from our previous run), we need to delete it first. Check it's a
+    // socket so we don't delete wrong files
+    struct stat st;
+    if (stat(ptr, &st) == 0) {
+        if (S_ISSOCK(st.st_mode))
+            unlink(ptr);
+    }
+
+    if (bind(unixrelays[i], (struct sockaddr *) &sa, sizeof(struct sockaddr_un))) {
+        ErrorF("Failed to bind unix sock\n");
+        return 1;
+    }
+
+    return 0;
+}
+
 char *extra_headers = NULL;
 unsigned extra_headers_len = 0;
 
@@ -374,6 +444,7 @@ void ddxUseMsg(void)
     ErrorF("-inetd                 has been launched from inetd\n");
     ErrorF("-http-header name=val  append this header to all HTTP responses\n");
     ErrorF("-noclipboard           disable clipboard settings modification via vncconfig utility\n");
+    ErrorF("-unixrelay name:path   create a local named unix relay socket\n");
     ErrorF("-verbose [n]           verbose startup messages\n");
     ErrorF("-quiet                 minimal startup messages\n");
     ErrorF("-version               show the server version\n");
@@ -426,6 +497,13 @@ ddxProcessArgument(int argc, char *argv[], int i)
 
         vfbInitializeDefaultScreens();
 	vfbInitializePixmapDepths();
+
+	unsigned r;
+	for (r = 0; r < MAX_UNIX_RELAYS; r++) {
+	    unixrelays[r] = -1;
+	    unixrelaynames[r][0] = '\0';
+	}
+
 	firstTime = FALSE;
 	vncInitRFB();
     }
@@ -692,6 +770,16 @@ ddxProcessArgument(int argc, char *argv[], int i)
 	return 1;
     }
 
+    if (strcasecmp(argv[i], "-unixrelay") == 0)
+    {
+	fail_unless_args(argc, i, 1);
+	++i;
+
+        if (addrelay(argv[i]))
+	    return 0;
+	return 2;
+    }
+
     if (!strcmp(argv[i], "-verbose")) {
         if (++i < argc && argv[i]) {
             char *end;