From 0a98d629447964f1d5d922d5012ee0c2cbf10694 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   | 64 +++++++++++++++++++++++++++++++++++++---
 rfb/rfb.h                | 17 +++++++++++
 3 files changed, 81 insertions(+), 4 deletions(-)

diff --git a/libvncserver/rfbserver.c b/libvncserver/rfbserver.c
index 7af6aed..fbedd9f 100644
--- a/libvncserver/rfbserver.c
+++ b/libvncserver/rfbserver.c
@@ -322,6 +322,10 @@ 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 bbc3d90..27515f2 100644
--- a/libvncserver/sockets.c
+++ b/libvncserver/sockets.c
@@ -589,6 +589,30 @@ 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)
+{
+    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 +634,10 @@ 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 +669,10 @@ 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 +709,18 @@ 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 +741,7 @@ 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 +797,22 @@ 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 +857,7 @@ 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 f982b40..ba9e898 100644
--- a/rfb/rfb.h
+++ b/rfb/rfb.h
@@ -415,6 +415,14 @@ 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;
@@ -696,6 +704,11 @@ 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;
 
 /**
@@ -748,8 +761,12 @@ 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);
-- 
2.17.1