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

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;