A significant rewrite of PPTP aliasing code.

PPTP links are no longer dropped by simple (and inappropriate in this
case) "inactivity timeout" procedure, only when requested through the
control connection.

It is now possible to have multiple PPTP servers running behind NAT.
Just redirect the incoming TCP traffic to port 1723, everything else
is done transparently.

Problems were reported and the fix was tested by:
		Michael Adler <Michael.Adler@compaq.com>,
		David Andersen <dga@lcs.mit.edu>

1 files changed, 111 insertions, 56 deletions

diff --git a/lib/libalias/alias_db.c b/lib/libalias/alias_db.c
index dcbf117..7b04548 100644
--- a/lib/libalias/alias_db.c
+++ b/lib/libalias/alias_db.c
@@ -158,7 +158,6 @@
 /* Timeouts (in seconds) for different link types */
 #define ICMP_EXPIRE_TIME             60
 #define UDP_EXPIRE_TIME              60
-#define PPTP_EXPIRE_TIME             60
 #define PROTO_EXPIRE_TIME            60
 #define FRAGMENT_ID_EXPIRE_TIME      10
 #define FRAGMENT_PTR_EXPIRE_TIME     30
@@ -422,7 +421,8 @@ StartPointIn(struct in_addr alias_addr,
     u_int n;
 
     n  = alias_addr.s_addr;
-    n += alias_port;
+    if (link_type != LINK_PPTP)
+	n += alias_port;
     n += link_type;
     return(n % LINK_TABLE_IN_SIZE);
 }
@@ -436,8 +436,10 @@ StartPointOut(struct in_addr src_addr, struct in_addr dst_addr,
 
     n  = src_addr.s_addr;
     n += dst_addr.s_addr;
-    n += src_port; 
-    n += dst_port;
+    if (link_type != LINK_PPTP) {
+	n += src_port; 
+	n += dst_port;
+    }
     n += link_type;
 
     return(n % LINK_TABLE_OUT_SIZE);
@@ -1004,7 +1006,7 @@ AddLink(struct in_addr  src_addr,
             link->expire_time = TCP_EXPIRE_INITIAL;
             break;
         case LINK_PPTP:
-            link->expire_time = PPTP_EXPIRE_TIME;
+            link->flags |= LINK_PERMANENT;	/* no timeout. */
             break;
         case LINK_FRAGMENT_ID:
             link->expire_time = FRAGMENT_ID_EXPIRE_TIME;
@@ -1389,7 +1391,8 @@ FindLinkIn(struct in_addr dst_addr,
     AddFragmentPtrLink(), FindFragmentPtr()
     FindProtoIn(), FindProtoOut()
     FindUdpTcpIn(), FindUdpTcpOut()
-    FindPptpIn(), FindPptpOut()
+    AddPptp(), FindPptpOutByCallId(), FindPptpInByCallId(),
+    FindPptpOutByPeerCallId(), FindPptpInByPeerCallId()
     FindOriginalAddress(), FindAliasAddress()
 
 (prototypes in alias_local.h)
@@ -1630,56 +1633,6 @@ FindUdpTcpOut(struct in_addr  src_addr,
 
 
 struct alias_link *
-FindPptpIn(struct in_addr dst_addr,
-          struct in_addr alias_addr,
-          u_short call_id)
-{
-    struct alias_link *link;
-
-    link = FindLinkIn(dst_addr, alias_addr,
-                      NO_DEST_PORT, call_id,
-                      LINK_PPTP, 1);
-
-    if (link == NULL && !(packetAliasMode & PKT_ALIAS_DENY_INCOMING))
-    {
-        struct in_addr target_addr;
-
-        target_addr = FindOriginalAddress(alias_addr);
-        link = AddLink(target_addr, dst_addr, alias_addr,
-                       call_id, NO_DEST_PORT, call_id,
-                       LINK_PPTP);
-    }
-
-    return(link);
-}
-
-
-struct alias_link * 
-FindPptpOut(struct in_addr  src_addr,
-            struct in_addr  dst_addr,
-            u_short         call_id)
-{
-    struct alias_link *link;
-
-    link = FindLinkOut(src_addr, dst_addr,
-                       call_id, NO_DEST_PORT,
-                       LINK_PPTP, 1);
-
-    if (link == NULL)
-    {
-        struct in_addr alias_addr;
-
-        alias_addr = FindAliasAddress(src_addr);
-        link = AddLink(src_addr, dst_addr, alias_addr,
-                       call_id, NO_DEST_PORT, GET_ALIAS_PORT,
-                       LINK_PPTP);
-    }
-
-    return(link);
-}
-
-
-struct alias_link *
 QueryUdpTcpIn(struct in_addr dst_addr,
               struct in_addr alias_addr,
               u_short        dst_port,
@@ -1740,6 +1693,97 @@ QueryUdpTcpOut(struct in_addr  src_addr,
     return(link);
 }
 
+struct alias_link *
+AddPptp(struct in_addr  src_addr,
+	struct in_addr  dst_addr,
+	struct in_addr  alias_addr,
+	u_int16_t       src_call_id)
+{
+    struct alias_link *link;
+
+    link = AddLink(src_addr, dst_addr, alias_addr,
+		   src_call_id, 0, GET_ALIAS_PORT,
+		   LINK_PPTP);
+
+    return (link);
+}
+
+
+struct alias_link *
+FindPptpOutByCallId(struct in_addr src_addr,
+		    struct in_addr dst_addr,
+		    u_int16_t      src_call_id)
+{
+    u_int i;
+    struct alias_link *link;
+
+    i = StartPointOut(src_addr, dst_addr, 0, 0, LINK_PPTP);
+    LIST_FOREACH(link, &linkTableOut[i], list_out)
+	if (link->link_type == LINK_PPTP &&
+	    link->src_addr.s_addr == src_addr.s_addr &&
+	    link->dst_addr.s_addr == dst_addr.s_addr &&
+	    link->src_port == src_call_id)
+		break;
+
+    return (link);
+}
+
+
+struct alias_link *
+FindPptpOutByPeerCallId(struct in_addr src_addr,
+			struct in_addr dst_addr,
+			u_int16_t      dst_call_id)
+{
+    u_int i;
+    struct alias_link *link;
+
+    i = StartPointOut(src_addr, dst_addr, 0, 0, LINK_PPTP);
+    LIST_FOREACH(link, &linkTableOut[i], list_out)
+	if (link->link_type == LINK_PPTP &&
+	    link->src_addr.s_addr == src_addr.s_addr &&
+	    link->dst_addr.s_addr == dst_addr.s_addr &&
+	    link->dst_port == dst_call_id)
+		break;
+
+    return (link);
+}
+
+
+struct alias_link *
+FindPptpInByCallId(struct in_addr dst_addr,
+		   struct in_addr alias_addr,
+		   u_int16_t      dst_call_id)
+{
+    u_int i;
+    struct alias_link *link;
+
+    i = StartPointIn(alias_addr, 0, LINK_PPTP);
+    LIST_FOREACH(link, &linkTableIn[i], list_in)
+	if (link->link_type == LINK_PPTP &&
+	    link->dst_addr.s_addr == dst_addr.s_addr &&
+	    link->alias_addr.s_addr == alias_addr.s_addr &&
+	    link->dst_port == dst_call_id)
+		break;
+
+    return (link);
+}
+
+
+struct alias_link *
+FindPptpInByPeerCallId(struct in_addr dst_addr,
+		       struct in_addr alias_addr,
+		       u_int16_t      alias_call_id)
+{
+    struct alias_link *link;
+
+    link = FindLinkIn(dst_addr, alias_addr,
+		      0/* any */, alias_call_id,
+		      LINK_PPTP, 0);
+
+
+    return (link);
+}
+
 
 struct alias_link * 
 FindRtspOut(struct in_addr  src_addr,
@@ -1845,6 +1889,7 @@ FindAliasAddress(struct in_addr original_addr)
     SetAckModified(), GetAckModified()
     GetDeltaAckIn(), GetDeltaSeqOut(), AddSeq()
     SetLastLineCrlfTermed(), GetLastLineCrlfTermed()
+    SetDestCallId()
 */
 
 
@@ -2227,6 +2272,16 @@ GetLastLineCrlfTermed(struct alias_link *link)
     return (link->flags & LINK_LAST_LINE_CRLF_TERMED);
 }
 
+void
+SetDestCallId(struct alias_link *link, u_int16_t cid)
+{
+
+    deleteAllLinks = 1;
+    link = ReLink(link, link->src_addr, link->dst_addr, link->alias_addr,
+		  link->src_port, cid, link->alias_port, link->link_type);
+    deleteAllLinks = 0;
+}
+
 
 /* Miscellaneous Functions