Add support for hybrid mode of operation. An user can provide -U option
to ptpd to have hybrid mode enabled. ptpd version higher than 2.2.0 may have
hybrid mode enabled by default in which case this patch should be removed.

diff -r 1a6514e3570d src/Makefile
--- a/src/Makefile	Fri Apr 03 18:07:43 2015 -0700
+++ b/src/Makefile	Fri Apr 03 21:12:39 2015 -0700
@@ -43,7 +43,7 @@
 #CFLAGS += -DDBG_SIGUSR2_CHANGE_DEBUG
 #CFLAGS += -DPTPD_FULL_OPTIONS
 
-#CFLAGS += -DPTP_EXPERIMENTAL
+CFLAGS += -DPTP_EXPERIMENTAL
 
 LDFLAGS+= -lm -lrt
 LDFLAGS += -lnsl -lsocket -lv12n -m64
diff -r 1a6514e3570d src/datatypes.h
--- a/src/datatypes.h	Fri Apr 03 18:07:43 2015 -0700
+++ b/src/datatypes.h	Fri Apr 03 21:12:39 2015 -0700
@@ -473,6 +473,11 @@
 
   Statistics statistics;
   
+#ifdef PTP_EXPERIMENTAL
+	Integer32 MasterAddr;                           // used for hybrid mode, when receiving announces
+	Integer32 LastSlaveAddr;                        // used for hybrid mode, when receiving delayreqs
+#endif
+
 } PtpClock;
 
 /**
diff -r 1a6514e3570d src/dep/datatypes_dep.h
--- a/src/dep/datatypes_dep.h	Fri Apr 03 18:07:43 2015 -0700
+++ b/src/dep/datatypes_dep.h	Fri Apr 03 21:12:39 2015 -0700
@@ -133,6 +133,12 @@
 
   /* used by IGMP refresh */
   struct in_addr interfaceAddr;
+
+#ifdef PTP_EXPERIMENTAL
+  /* used for Hybrid mode */
+  Integer32 lastRecvAddr;
+#endif
+
 } NetPath;
 
 #endif /*DATATYPES_DEP_H_*/
diff -r 1a6514e3570d src/dep/msg.c
--- a/src/dep/msg.c	Fri Apr 03 18:07:43 2015 -0700
+++ b/src/dep/msg.c	Fri Apr 03 21:12:39 2015 -0700
@@ -40,6 +40,10 @@
 
 #include "../ptpd.h"
 
+#ifdef PTP_EXPERIMENTAL
+extern RunTimeOpts rtOpts; 
+#endif
+
 /*Unpack Header from IN buffer to msgTmpHeader field */
 void 
 msgUnpackHeader(Octet * buf, MsgHeader * header)
@@ -328,6 +332,12 @@
 	/* Table 19 */
 	*(UInteger16 *) (buf + 2) = flip16(DELAY_RESP_LENGTH);
 	*(UInteger8 *) (buf + 4) = header->domainNumber;
+
+#ifdef PTP_EXPERIMENTAL
+	if(rtOpts.do_hybrid_mode)    
+		*(char *)(buf + 6) |= PTP_UNICAST;
+#endif
+
 	memset((buf + 8), 0, 8);
 
 	/* Copy correctionField of PdelayReqMessage */
diff -r 1a6514e3570d src/dep/startup.c
--- a/src/dep/startup.c	Fri Apr 03 18:07:43 2015 -0700
+++ b/src/dep/startup.c	Fri Apr 03 21:12:39 2015 -0700
@@ -662,7 +662,7 @@
 #endif
 */
 
-   const char *getopt_string = "?HgGWb:cCf:ST:dDPR:xO:tM:a:w:u:ehzl:o:i:n:N:y:m:v:r:s:p:q:Y:BjLV:XZKF";
+   const char *getopt_string = "?HgGWb:cCf:ST:dDPR:xO:tM:a:w:u:ehzl:o:i:n:N:y:m:v:r:s:p:q:Y:BjLV:XZKFU";
 
   /* parse command line arguments */
   while ((c = getopt(argc, argv, getopt_string)) != -1) {
--- a/src/ptpd2.8	2015-05-18 14:05:20.934031705 -0700
+++ b/src/ptpd2.8	2015-05-18 13:59:54.195214157 -0700
@@ -27,6 +27,7 @@
 [-b NAME]
 [-K]
 [-u ADDRESS]
+[-U]
 [-e]
 [-h]
 [-l NUMBER,NUMBER]
@@ -204,6 +205,9 @@
 .B \-u ADDRESS
 also send uni-cast to ADDRESS
 .TP
+.B \-U
+enable hybrid mode which uses both unicast and multicast
+.TP
 .B \-e
 run in ethernet mode (currently unimplemented)
 .TP