Add Cisco Skinny Station protocol support to libalias, natd, and ppp.

Skinny is the protocol used by Cisco IP phones to talk to Cisco Call
Managers.  With this code, one can use a Cisco IP phone behind a FreeBSD
NAT gateway.

Currently, having the Call Manager behind the NAT gateway is not supported.
More information on enabling Skinny support in libalias, natd, and ppp
can be found in those applications' manpages.

PR:		55843
Reviewed by:	ru
Approved by:	ru
MFC after:	30 days

6 files changed, 30 insertions, 1 deletions

diff --git a/sys/netinet/libalias/Makefile b/sys/netinet/libalias/Makefile
index bf26f05..f262be1 100644
--- a/sys/netinet/libalias/Makefile
+++ b/sys/netinet/libalias/Makefile
@@ -5,7 +5,7 @@ SHLIBDIR?= /lib
 SHLIB_MAJOR=	4
 MAN=	libalias.3
 SRCS=	alias.c alias_cuseeme.c alias_db.c alias_ftp.c alias_irc.c \
-	alias_nbt.c alias_pptp.c alias_proxy.c alias_smedia.c \
+	alias_nbt.c alias_pptp.c alias_proxy.c alias_skinny.c alias_smedia.c \
 	alias_util.c
 INCS=	alias.h
 
diff --git a/sys/netinet/libalias/alias.c b/sys/netinet/libalias/alias.c
index 54839ff..cf93a74 100644
--- a/sys/netinet/libalias/alias.c
+++ b/sys/netinet/libalias/alias.c
@@ -917,6 +917,9 @@ TcpAliasIn(struct ip *pip)
         if (ntohs(tc->th_dport) == PPTP_CONTROL_PORT_NUMBER
          || ntohs(tc->th_sport) == PPTP_CONTROL_PORT_NUMBER)
             AliasHandlePptpIn(pip, link);
+        else if (skinnyPort != 0 && (ntohs(tc->th_dport) == skinnyPort
+         || ntohs(tc->th_sport) == skinnyPort))
+            AliasHandleSkinny(pip, link);
 
         alias_address = GetAliasAddress(link);
         original_address = GetOriginalAddress(link);
@@ -1098,6 +1101,9 @@ TcpAliasOut(struct ip *pip, int maxpacketsize)
         else if (ntohs(tc->th_dport) == PPTP_CONTROL_PORT_NUMBER
          || ntohs(tc->th_sport) == PPTP_CONTROL_PORT_NUMBER)
             AliasHandlePptpOut(pip, link);
+        else if (skinnyPort != 0 && (ntohs(tc->th_sport) == skinnyPort
+         || ntohs(tc->th_dport) == skinnyPort))
+            AliasHandleSkinny(pip, link);
 
 /* Adjust TCP checksum since source port is being aliased */
 /* and source address is being altered                    */
diff --git a/sys/netinet/libalias/alias.h b/sys/netinet/libalias/alias.h
index eb35bf7..b0c75c9 100644
--- a/sys/netinet/libalias/alias.h
+++ b/sys/netinet/libalias/alias.h
@@ -45,6 +45,7 @@
 void	 PacketAliasInit(void);
 void	 PacketAliasSetAddress(struct in_addr _addr);
 void	 PacketAliasSetFWBase(unsigned int _base, unsigned int _num);
+void	 PacketAliasSetSkinnyPort(unsigned int _port);
 unsigned int
 	 PacketAliasSetMode(unsigned int _flags, unsigned int _mask);
 void	 PacketAliasUninit(void);
diff --git a/sys/netinet/libalias/alias_db.c b/sys/netinet/libalias/alias_db.c
index ec25070..e53e94d 100644
--- a/sys/netinet/libalias/alias_db.c
+++ b/sys/netinet/libalias/alias_db.c
@@ -398,6 +398,9 @@ static int fireWallFD = -1;          /* File descriptor to be able to   */
                                      /* flag.                           */
 #endif
 
+unsigned int skinnyPort = 0;         /* TCP port used by the Skinny     */
+                                     /* protocol.                       */
+
 
 
 
@@ -2948,3 +2951,8 @@ PacketAliasSetFWBase(unsigned int base, unsigned int num) {
     fireWallNumNums = num;
 #endif
 }
+
+void
+PacketAliasSetSkinnyPort(unsigned int port) {
+    skinnyPort = port;
+}
diff --git a/sys/netinet/libalias/alias_local.h b/sys/netinet/libalias/alias_local.h
index 4428d2a..d207f9f 100644
--- a/sys/netinet/libalias/alias_local.h
+++ b/sys/netinet/libalias/alias_local.h
@@ -74,6 +74,7 @@
 /* Globals */
 
 extern int packetAliasMode;
+extern unsigned int skinnyPort;
 
 /* Prototypes */
 
@@ -212,6 +213,9 @@ int	 AliasHandleUdpNbtNS(struct ip *_pip, struct alias_link *_link,
 void	 AliasHandleCUSeeMeOut(struct ip *_pip, struct alias_link *_link);
 void	 AliasHandleCUSeeMeIn(struct ip *_pip, struct in_addr _original_addr);
 
+/* Skinny routines */
+void	 AliasHandleSkinny(struct ip *_pip, struct alias_link *_link);
+
 /* Transparent proxy routines */
 int	 ProxyCheck(struct ip *_pip, struct in_addr *_proxy_server_addr,
 	    u_short *_proxy_server_port);
diff --git a/sys/netinet/libalias/libalias.3 b/sys/netinet/libalias/libalias.3
index a75cd2b..e5ef09e 100644
--- a/sys/netinet/libalias/libalias.3
+++ b/sys/netinet/libalias/libalias.3
@@ -265,6 +265,16 @@ Set firewall range allocated for punching firewall holes (with the
 flag).
 The range will be cleared for all rules on initialization.
 .Ed
+.Pp
+.Ft void
+.Fn PacketAliasSkinnyPort "unsigned int port"
+.Bd -ragged -offset indent
+Set the TCP port used by the Skinny Station protocol.
+Skinny is used by Cisco IP phones to communicate with
+Cisco Call Managers to set up voice over IP calls.
+If this is not set, Skinny aliasing will not be done.
+The typical port used by Skinny is 2000.
+.Ed
 .Sh PACKET HANDLING
 The packet handling functions are used to modify incoming (remote to local)
 and outgoing (local to remote) packets.