Add Dead Letter Header parser

Author: ibmmqmet

CHANGELOG.md

@@ -5,6 +5,7 @@
 * Samples updated to use "defer" instead of just suggesting it
 * Add support for MQCB/MQCTL callback functions
 * Add support for MQBEGIN transaction management
+* Add Dead Letter Header parser
 
 ## November 2018 - v3.2.0
 * Added GetPlatform to mqmetric so it can be used as a label/tag in collectors

README.md

@@ -125,8 +125,6 @@ At this point, you should have a compiled copy of the program in `$GOPATH/bin`.
 
 All regular MQI verbs are now available through the `ibmmq` package.
 
-There are no structure handlers for message headers such as MQRFH2 or MQDLH.
-
 ## History
 
 See [CHANGELOG](CHANGELOG.md) in this directory.

ibmmq/mqi.go

@@ -57,6 +57,7 @@ import "C"
 
 import (
 	"encoding/binary"
+	"io"
 	"strings"
 	"unsafe"
 )
@@ -120,6 +121,8 @@ func (e *MQReturn) Error() string {
 	return mqstrerror(e.verb, C.MQLONG(e.MQCC), C.MQLONG(e.MQRC))
 }
 
+var endian binary.ByteOrder // Used by structure formatters such as MQCFH
+
 /*
  * Copy a Go string in "strings"
  * to a fixed-size C char array such as MQCHAR12
@@ -139,7 +142,7 @@ func setMQIString(a *C.char, v string, l int) {
 /*
  * The C.GoStringN function can return strings that include
  * NUL characters (which is not really what is expected for a C string-related
- * function). So we have a utility function to remove any trailing nulls
+ * function). So we have a utility function to remove any trailing nulls and spaces
  */
 func trimStringN(c *C.char, l C.int) string {
 	var rc string
@@ -150,7 +153,7 @@ func trimStringN(c *C.char, l C.int) string {
 	} else {
 		rc = s[0:i]
 	}
-	return rc
+	return strings.TrimSpace(rc)
 }
 
 /*
@@ -1261,3 +1264,30 @@ func (handle *MQMessageHandle) InqMP(goimpo *MQIMPO, gopd *MQPD, name string) (s
 
 	return goimpo.ReturnedName, propertyValue, nil
 }
+
+/*
+GetHeader returns a structure containing a parsed-out version of an MQI
+message header such as the MQDLH (which is currently the only structure
+supported). Other structures like the RFH2 could follow.
+
+The caller of this function needs to cast the returned structure to the
+specific type in order to reference the fields.
+*/
+func GetHeader(md *MQMD, buf []byte) (interface{}, int, error) {
+	switch md.Format {
+	case MQFMT_DEAD_LETTER_HEADER:
+		return getHeaderDLH(md, buf)
+	}
+
+	mqreturn := &MQReturn{MQCC: int32(MQCC_FAILED),
+		MQRC: int32(MQRC_FORMAT_NOT_SUPPORTED),
+	}
+
+	return nil, 0, mqreturn
+}
+
+func readStringFromFixedBuffer(r io.Reader, l int32) string {
+	tmpBuf := make([]byte, l)
+	binary.Read(r, endian, tmpBuf)
+	return strings.TrimSpace(string(tmpBuf))
+}

ibmmq/mqiDLH.go

@@ -0,0 +1,148 @@
+package ibmmq
+
+/*
+  Copyright (c) IBM Corporation 2016,2018
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+   Contributors:
+     Mark Taylor - Initial Contribution
+*/
+
+/*
+#include <stdlib.h>
+#include <cmqc.h>
+#include <cmqcfc.h>
+*/
+import "C"
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+type MQDLH struct {
+	Reason         int32
+	DestQName      string
+	DestQMgrName   string
+	Encoding       int32
+	CodedCharSetId int32
+	Format         string
+	PutApplType    int32
+	PutApplName    string
+	PutDate        string
+	PutTime        string
+	strucLength    int // Not exported
+}
+
+func NewMQDLH(md *MQMD) *MQDLH {
+	dlh := new(MQDLH)
+	dlh.Reason = MQRC_NONE
+	dlh.CodedCharSetId = MQCCSI_UNDEFINED
+	dlh.PutApplType = 0
+	dlh.PutApplName = ""
+	dlh.PutTime = ""
+	dlh.PutDate = ""
+	dlh.Format = ""
+	dlh.DestQName = ""
+	dlh.DestQMgrName = ""
+
+	dlh.strucLength = int(MQDLH_CURRENT_LENGTH)
+
+	if md != nil {
+		dlh.Encoding = md.Encoding
+		if md.CodedCharSetId == MQCCSI_DEFAULT {
+			dlh.CodedCharSetId = MQCCSI_INHERIT
+		} else {
+			dlh.CodedCharSetId = md.CodedCharSetId
+		}
+		dlh.Format = md.Format
+
+		md.Format = MQFMT_DEAD_LETTER_HEADER
+		md.MsgType = MQMT_REPORT
+		md.CodedCharSetId = MQCCSI_Q_MGR
+	}
+
+	if (C.MQENC_NATIVE % 2) == 0 {
+		endian = binary.LittleEndian
+	} else {
+		endian = binary.BigEndian
+	}
+
+	return dlh
+}
+
+func (dlh *MQDLH) Bytes() []byte {
+	buf := make([]byte, dlh.strucLength)
+	offset := 0
+
+	copy(buf[offset:], "DLH ")
+	offset += 4
+	endian.PutUint32(buf[offset:], uint32(MQDLH_CURRENT_VERSION))
+	offset += 4
+	endian.PutUint32(buf[offset:], uint32(dlh.Reason))
+	offset += 4
+	copy(buf[offset:], dlh.DestQName)
+	offset += int(MQ_OBJECT_NAME_LENGTH)
+	copy(buf[offset:], dlh.DestQMgrName)
+	offset += int(MQ_Q_MGR_NAME_LENGTH)
+	endian.PutUint32(buf[offset:], uint32(dlh.Encoding))
+	offset += 4
+	endian.PutUint32(buf[offset:], uint32(dlh.CodedCharSetId))
+	offset += 4
+	copy(buf[offset:], dlh.Format)
+	offset += int(MQ_FORMAT_LENGTH)
+	endian.PutUint32(buf[offset:], uint32(dlh.PutApplType))
+	offset += 4
+	copy(buf[offset:], dlh.PutApplName)
+	offset += int(MQ_PUT_APPL_NAME_LENGTH)
+	copy(buf[offset:], dlh.PutDate)
+	offset += int(MQ_PUT_DATE_LENGTH)
+	copy(buf[offset:], dlh.PutTime)
+	offset += int(MQ_PUT_TIME_LENGTH)
+
+	return buf
+}
+
+/*
+We have a byte array for the message contents. The start of that buffer
+is the MQDLH structure. We read the bytes from that fixed header to match
+the C structure definition for each field. The DLH does not have multiple
+versions defined so we don't need to check that as we go through.
+*/
+func getHeaderDLH(md *MQMD, buf []byte) (*MQDLH, int, error) {
+
+	var version int32
+
+	dlh := NewMQDLH(nil)
+
+	r := bytes.NewBuffer(buf)
+	_ = readStringFromFixedBuffer(r, 4) // StrucId
+	binary.Read(r, endian, &version)
+	binary.Read(r, endian, &dlh.Reason)
+	dlh.DestQName = readStringFromFixedBuffer(r, MQ_OBJECT_NAME_LENGTH)
+	dlh.DestQMgrName = readStringFromFixedBuffer(r, MQ_Q_MGR_NAME_LENGTH)
+
+	binary.Read(r, endian, &dlh.Encoding)
+	binary.Read(r, endian, &dlh.CodedCharSetId)
+
+	dlh.Format = readStringFromFixedBuffer(r, MQ_FORMAT_LENGTH)
+
+	binary.Read(r, endian, &dlh.PutApplType)
+
+	dlh.PutApplName = readStringFromFixedBuffer(r, MQ_PUT_APPL_NAME_LENGTH)
+	dlh.PutDate = readStringFromFixedBuffer(r, MQ_PUT_DATE_LENGTH)
+	dlh.PutTime = readStringFromFixedBuffer(r, MQ_PUT_TIME_LENGTH)
+
+	return dlh, dlh.strucLength, nil
+}

ibmmq/mqiPCF.go

@@ -47,8 +47,6 @@ type MQCFH struct {
 	ParameterCount int32
 }
 
-var endian binary.ByteOrder
-
 /*
 PCFParameter is a structure containing the data associated with
 various types of PCF element. Use the Type field to decide which

mqmetric/discover.go

@@ -865,7 +865,7 @@ func formatDescription(elem *MonElement) string {
 		// we have to ensure uniqueness.
 		if strings.Contains(elem.Description, "byte count") {
 			s = s + "_bytes"
-		} else if strings.HasSuffix(elem.Description," count") && !strings.Contains(s,"_count") {
+		} else if strings.HasSuffix(elem.Description, " count") && !strings.Contains(s, "_count") {
 			s = s + "_count"
 		}
 	}