From fb4b12407e869c3da33df65ed3a43ef87aeae1c4 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Jonas=20=C3=85dahl?= <jadahl@gmail.com>

Date: Mon, 11 Jun 2018 23:47:02 +0200

Subject: [PATCH 1/2] libvncserver: Add API to add custom I/O entry points

Add API to make it possible to channel RFB input and output through

another layer, for example TLS. This is done by making it possible to

override the default read/write/peek functions.

---

 libvncserver/rfbserver.c |  4 ++

 libvncserver/sockets.c   | 79 ++++++++++++++++++++++++++++++++++++----

 rfb/rfb.h                | 17 +++++++++

 3 files changed, 93 insertions(+), 7 deletions(-)

diff --git a/libvncserver/rfbserver.c b/libvncserver/rfbserver.c

index bc9cc117..0c8ee735 100644

--- a/libvncserver/rfbserver.c

+++ b/libvncserver/rfbserver.c

@@ -319,6 +319,10 @@ rfbNewTCPOrUDPClient(rfbScreenInfoPtr rfbScreen,

     cl->screen = rfbScreen;

     cl->sock = sock;

+    cl->readFromSocket = rfbDefaultReadFromSocket;

+    cl->peekAtSocket = rfbDefaultPeekAtSocket;

+    cl->hasPendingOnSocket = rfbDefaultHasPendingOnSocket;

+    cl->writeToSocket = rfbDefaultWriteToSocket;

     cl->viewOnly = FALSE;

     /* setup pseudo scaling */

     cl->scaledScreen = rfbScreen;

diff --git a/libvncserver/sockets.c b/libvncserver/sockets.c

index bbc3d90d..4874d4b6 100644

--- a/libvncserver/sockets.c

+++ b/libvncserver/sockets.c

@@ -126,6 +126,9 @@ int deny_severity=LOG_WARNING;

 int rfbMaxClientWait = 20000;   /* time (ms) after which we decide client has

                                    gone away - needed to stop us hanging */

+static rfbBool

+rfbHasPendingOnSocket(rfbClientPtr cl);

+

 static rfbBool

 rfbNewConnectionFromSock(rfbScreenInfoPtr rfbScreen, int sock)

 {

@@ -370,16 +373,20 @@ rfbCheckFds(rfbScreenInfoPtr rfbScreen,long usec)

 	tv.tv_usec = usec;

 	nfds = select(rfbScreen->maxFd + 1, &fds, NULL, NULL /* &fds */, &tv;;

 	if (nfds == 0) {

+            rfbBool hasPendingData = FALSE;

+

 	    /* timed out, check for async events */

             i = rfbGetClientIterator(rfbScreen);

             while((cl = rfbClientIteratorNext(i))) {

                 if (cl->onHold)

                     continue;

+                hasPendingData |= rfbHasPendingOnSocket(cl);

                 if (FD_ISSET(cl->sock, &(rfbScreen->allFds)))

                     rfbSendFileTransferChunk(cl);

             }

             rfbReleaseClientIterator(i);

-	    return result;

+            if (!hasPendingData)

+                return result;

 	}

 	if (nfds < 0) {

@@ -455,9 +462,11 @@ rfbCheckFds(rfbScreenInfoPtr rfbScreen,long usec)

 	    if (cl->onHold)

 		continue;

-            if (FD_ISSET(cl->sock, &(rfbScreen->allFds)))

+            if (rfbHasPendingOnSocket (cl) ||

+                FD_ISSET(cl->sock, &(rfbScreen->allFds)))

             {

-                if (FD_ISSET(cl->sock, &fds))

+                if (rfbHasPendingOnSocket (cl) ||

+                    FD_ISSET(cl->sock, &fds))

                 {

 #ifdef LIBVNCSERVER_WITH_WEBSOCKETS

                     do {

@@ -589,6 +598,30 @@ rfbConnect(rfbScreenInfoPtr rfbScreen,

     return sock;

 }

+int

+rfbDefaultReadFromSocket(rfbClientPtr cl, char *buf, int len)

+{

+    return read(cl->sock, buf, len);

+}

+

+static int

+rfbReadFromSocket(rfbClientPtr cl, char *buf, int len)

+{

+    return cl->readFromSocket(cl, buf, len);

+}

+

+rfbBool

+rfbDefaultHasPendingOnSocket(rfbClientPtr cl)

+{

+    return FALSE;

+}

+

+static rfbBool

+rfbHasPendingOnSocket(rfbClientPtr cl)

+{

+    return cl->hasPendingOnSocket(cl);

+}

+

 /*

  * ReadExact reads an exact number of bytes from a client.  Returns 1 if

  * those bytes have been read, 0 if the other end has closed, or -1 if an error

@@ -610,10 +643,10 @@ rfbReadExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)

         } else if (cl->sslctx) {

 	    n = rfbssl_read(cl, buf, len);

 	} else {

-            n = read(sock, buf, len);

+            n = rfbReadFromSocket(cl, buf, len);

         }

 #else

-        n = read(sock, buf, len);

+        n = rfbReadFromSocket(cl, buf, len);

 #endif

         if (n > 0) {

@@ -645,6 +678,10 @@ rfbReadExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)

 		    continue;

 	    }

 #endif

+

+            if (rfbHasPendingOnSocket(cl))

+                continue;

+

             FD_ZERO(&fds);

             FD_SET(sock, &fds);

             tv.tv_sec = timeout / 1000;

@@ -681,6 +718,18 @@ int rfbReadExact(rfbClientPtr cl,char* buf,int len)

     return(rfbReadExactTimeout(cl,buf,len,rfbMaxClientWait));

 }

+int

+rfbDefaultPeekAtSocket(rfbClientPtr cl, char *buf, int len)

+{

+    return recv(cl->sock, buf, len, MSG_PEEK);

+}

+

+int

+rfbPeekAtSocket(rfbClientPtr cl, char *buf, int len)

+{

+    cl->peekAtSocket(cl, buf, len);

+}

+

 /*

  * PeekExact peeks at an exact number of bytes from a client.  Returns 1 if

  * those bytes have been read, 0 if the other end has closed, or -1 if an

@@ -701,7 +750,7 @@ rfbPeekExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)

 	    n = rfbssl_peek(cl, buf, len);

 	else

 #endif

-	    n = recv(sock, buf, len, MSG_PEEK);

+            n = rfbPeekAtSocket(cl, buf, len);

         if (n == len) {

@@ -757,6 +806,22 @@ rfbPeekExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)

     return 1;

 }

+int

+rfbDefaultWriteToSocket(rfbClientPtr cl,

+			const char *buf,

+			int len)

+{

+    return write(cl->sock, buf, len);

+}

+

+static int

+rfbWriteToSocket(rfbClientPtr cl,

+		 const char *buf,

+		 int len)

+{

+    return cl->writeToSocket(cl, buf, len);

+}

+

 /*

  * WriteExact writes an exact number of bytes to a client.  Returns 1 if

  * those bytes have been written, or -1 if an error occurred (errno is set to

@@ -801,7 +866,7 @@ rfbWriteExact(rfbClientPtr cl,

 	    n = rfbssl_write(cl, buf, len);

 	else

 #endif

-	    n = write(sock, buf, len);

+	    n = rfbWriteToSocket(cl, buf, len);

         if (n > 0) {

diff --git a/rfb/rfb.h b/rfb/rfb.h

index c6edc119..2e5597a9 100644

--- a/rfb/rfb.h

+++ b/rfb/rfb.h

@@ -414,6 +414,14 @@ typedef struct sraRegion* sraRegionPtr;

 typedef void (*ClientGoneHookPtr)(struct _rfbClientRec* cl);

+typedef int (*ClientReadFromSocket)(struct _rfbClientRec* cl,

+                                    char *buf, int len);

+typedef int (*ClientPeekAtSocket)(struct _rfbClientRec* cl,

+                                  char *buf, int len);

+typedef rfbBool (*ClientHasPendingOnSocket)(struct _rfbClientRec* cl);

+typedef int (*ClientWriteToSocket)(struct _rfbClientRec* cl,

+                                   const char *buf, int len);

+

 typedef struct _rfbFileTransferData {

   int fd;

   int compressionEnabled;

@@ -695,6 +703,11 @@ typedef struct _rfbClientRec {

     wsCtx     *wsctx;

     char *wspath;                          /* Requests path component */

 #endif

+

+    ClientReadFromSocket readFromSocket;         /* Read data from socket */

+    ClientPeekAtSocket peekAtSocket;             /* Peek at data from socket */

+    ClientHasPendingOnSocket hasPendingOnSocket; /* Peek at data from socket */

+    ClientWriteToSocket writeToSocket;           /* Write data to socket */

 } rfbClientRec, *rfbClientPtr;

 /**

@@ -747,8 +760,12 @@ extern void rfbDisconnectUDPSock(rfbScreenInfoPtr rfbScreen);

 extern void rfbCloseClient(rfbClientPtr cl);

 extern int rfbReadExact(rfbClientPtr cl, char *buf, int len);

 extern int rfbReadExactTimeout(rfbClientPtr cl, char *buf, int len,int timeout);

+extern int rfbDefaultReadFromSocket(rfbClientPtr cl, char *buf, int len);

 extern int rfbPeekExactTimeout(rfbClientPtr cl, char *buf, int len,int timeout);

+extern int rfbDefaultPeekAtSocket(rfbClientPtr cl, char *buf, int len);

+extern rfbBool rfbDefaultHasPendingOnSocket(rfbClientPtr cl);

 extern int rfbWriteExact(rfbClientPtr cl, const char *buf, int len);

+extern int rfbDefaultWriteToSocket(rfbClientPtr cl, const char *buf, int len);

 extern int rfbCheckFds(rfbScreenInfoPtr rfbScreen,long usec);

 extern int rfbConnect(rfbScreenInfoPtr rfbScreen, char* host, int port);

 extern int rfbConnectToTcpAddr(char* host, int port);

-- 

2.23.0