mc: guid: Fix byte ordering to follow IPMI spec

Before this commit the bytes for the GUID 'node' part were displayed in
reverse order as if they were reported by BMC according to SMBIOS
specification, not accordint to IPMI.

The field order in guid_t was also specified according to RFC4122/SMBIOS,
which is the reverse of IPMI specification. It has now been fixed.

The time_low field of GUID was taken directly, without taking in
account the ipmitool host endianness. It is now properly converted
from IPMI little-endian to host byte order. Other GUID fields are
also properly converted now. As of now, ipmitool does not generally work
properly when built for a big-endian target, but that's out of scope
of this commit.

Please note that this commit most probably breaks the output of
`ipmitool mc guid` with most existing BMC implementations, but that's
just an indication of them being broken. A follow-up commit will
re-add support for the broken behavior.

Partially resolves ipmitool/ipmitool#25

Signed-off-by: Alexander Amelkin <alexander@amelkin.msk.ru>

2 files changed, 24 insertions, 12 deletions

diff --git a/include/ipmitool/ipmi_mc.h b/include/ipmitool/ipmi_mc.h
index 4e177e5..a4096fd 100644
--- a/include/ipmitool/ipmi_mc.h
+++ b/include/ipmitool/ipmi_mc.h
@@ -103,12 +103,17 @@ struct ipm_devid_rsp {
 #pragma pack(1)
 #endif
 struct ipmi_guid_t {
-	uint32_t  time_low;	/* timestamp low field */
-	uint16_t  time_mid;	/* timestamp middle field */
-	uint16_t  time_hi_and_version; /* timestamp high field and version number */
-	uint8_t   clock_seq_hi_variant;/* clock sequence high field and variant */
-	uint8_t   clock_seq_low; /* clock sequence low field */
 	uint8_t   node[6];	/* node */
+	union {
+		struct {
+			uint8_t   clock_seq_low; /* clock sequence low field */
+			uint8_t   clock_seq_hi_variant;/* clock sequence high field and variant */
+		};
+		uint16_t clock_seq_variant;
+	};
+	uint16_t  time_hi_and_version; /* timestamp high field and version number */
+	uint16_t  time_mid;	/* timestamp middle field */
+	uint32_t  time_low;	/* timestamp low field */
 } ATTRIBUTE_PACKING;
 #ifdef HAVE_PRAGMA_PACK
 #pragma pack(0)
diff --git a/lib/ipmi_mc.c b/lib/ipmi_mc.c
index ee75e95..34f9978 100644
--- a/lib/ipmi_mc.c
+++ b/lib/ipmi_mc.c
@@ -533,14 +533,21 @@ ipmi_mc_print_guid(struct ipmi_guid_t guid)
 	memset(tbuf, 0, 40);
 	struct tm *tm;
 
-	/* Kipp - changed order of last field (node) to follow specification */
 	printf("System GUID  : %08x-%04x-%04x-%04x-%02x%02x%02x%02x%02x%02x\n",
-	       guid.time_low, guid.time_mid, guid.time_hi_and_version,
-	       guid.clock_seq_hi_variant << 8 | guid.clock_seq_low,
-	       guid.node[0], guid.node[1], guid.node[2],
-	       guid.node[3], guid.node[4], guid.node[5]);
-
-	s = (time_t)guid.time_low; /* Kipp - removed the BSWAP_32, it was not needed here */
+	       /* We're displaying GUID as hex integers. Thus we need them to be
+	        * in host byte order before we display them. However, according to
+	        * IPMI 2.0, all GUID fields are in LSB first (Little Endian)
+	        * format. Hence the ipmiXtoh() calls:
+	        */
+	       ipmi32toh(&guid.time_low),
+	       ipmi16toh(&guid.time_mid),
+	       ipmi16toh(&guid.time_hi_and_version),
+	       ipmi16toh(&guid.clock_seq_variant),
+	       /* The node part is shown as bytes, so no additional conversion */
+	       guid.node[5], guid.node[4], guid.node[3],
+	       guid.node[2], guid.node[1], guid.node[0]);
+
+	s = (time_t)ipmi32toh(&guid.time_low);
 	if(time_in_utc)
 		tm = gmtime(&s);
 	else