Initial commit

.gitignore

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+.idea/
+*.DS_Store
+examples/

.travis.yml

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+language: go
+
+go:
+  - 1.14.x
+
+before_install:
+  - go get -t -v ./...
+  - curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.24.0
+
+script:
+  - go test ./... -race -coverprofile=coverage.txt -covermode=atomic
+  - make
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)

Makefile

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+### Required tools
+GOTOOLS_CHECK = golangci-lint
+
+all: fmt ensure-deps linter test
+
+### Testing
+test:
+	go test ./... -covermode=atomic -coverpkg=./... -count=1 -race
+
+test-cover:
+	go test ./... -covermode=atomic -coverprofile=/tmp/coverage.out -coverpkg=./... -count=1
+	go tool cover -html=/tmp/coverage.out
+
+test-integration:
+	go test -tags integration ./... -covermode=atomic -coverpkg=./... -count=1 -race
+
+### Formatting, linting, and deps
+fmt:
+	go fmt ./...
+
+ensure-deps:
+	@echo "==> Running go mod tidy"
+	go mod download
+	go mod tidy
+
+linter:
+	@echo "==> Running linter"
+	golangci-lint run ./...
+
+# To avoid unintended conflicts with file names, always add to .PHONY
+# unless there is a reason not to.
+# https://www.gnu.org/software/make/manual/html_node/Phony-Targets.html
+.PHONY: check_tools test test-cover fmt linter ensure-deps

README.md

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+[![codecov](https://codecov.io/gh/jattento/go-iso8583/branch/master/graph/badge.svg)](https://codecov.io/gh/jattento/go-iso8583)
+[![Build Status](https://travis-ci.com/jattento/go-iso8583.svg?branch=master)](https://travis-ci.com/jattento/go-iso8583)
+
+# go-iso8583
+
+An easy to use, yet flexible marshaler for ISO-8583.
+
+API [godoc](https://godoc.org/github.com/jattento/go-iso8583/pkg/iso8583) documentation.
+
+This library provides:
+- Marshal and Unmarshal functions with his respective interfaces
+including MTI, VAR, LLVAR, LLLVAR and bitmaps fields ready for use
+but with the possibility to easily add new field types.
+- Inbuid Support for ASCII and EBCDIC but not limited to them
+
+
+## Installation
+
+To install go-iso8583 package, you need to install Go and set your Go workspace first.
+
+1. First you need [Go](https://golang.org/) installed, then you can use the below Go command to install go-iso8583.
+```sh
+$ go get -u github.com/jattento/go-iso8583/iso8583
+```
+
+2. Import it in your code:
+```go
+import "github.com/jattento/go-iso8583/pkg/iso8583"
+```
+
+## Quick start
+
+```go
+import "github.com/go-iso8583/pkg/iso8583"
+
+type PurchaseRequest struct {
+	MTI                    iso8583.MTI    `iso8583:"mti"`
+	FirstBitmap            iso8583.BITMAP `iso8583:"bitmap,length:64"` // length is the maximum amount of represented elements.
+	SecondBitmap           iso8583.BITMAP `iso8583:"1,length:64"`      // length is the maximum amount of represented elements.
+	PAN                    iso8583.LLVAR  `iso8583:"2"`
+	ProcessingCode         iso8583.VAR    `iso8583:"3"`
+	Amount                 iso8583.VAR    `iso8583:"4,encoding:ebcdic"` // By default ASCII is assumed but dont limit yourself!
+	DateTime               iso8583.VAR    `iso8583:"7"`
+	SystemTraceAuditNumber iso8583.VAR    `iso8583:"11,omitempty"` // omitempty is supported!
+	LocalTransactionTime   iso8583.VAR    `iso8583:"12"`
+	LocalTransactionDate   iso8583.VAR    `iso8583:"-"` // You can explicitly ignore a field.
+	ExpirationDate         iso8583.VAR    `iso8583:"14"`
+	MerchantType           iso8583.VAR    `iso8583:"18"`
+	ICC                    iso8583.LLLVAR `iso8583:"55"`
+	SettlementCode         iso8583.VAR    `iso8583:"66"`
+	MessageNumber          iso8583.VAR    `iso8583:"71"`
+	TransactionDescriptor  iso8583.VAR    `iso8583:"104"`
+}
+
+func GenerateStaticReqBytes() ([]byte, error) {
+	req := PurchaseRequest{
+		MTI: "0100",
+		// FirstBitmap is generated by library
+		// SecondBitmap is generated by library
+		PAN: "54000000000000111", // LL part is added by library!
+		ProcessingCode: "1000",
+		Amount: "000000000100",
+		MessageNumber: "1",
+	}
+
+	byt, err := iso8583.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+
+	return byt, nil
+}
+```
+
+```go
+import "github.com/go-iso8583/pkg/iso8583"
+
+type PurchaseResponse struct {
+	MTI                    iso8583.MTI    `iso8583:"mti,length:4"`
+	FirstBitmap            iso8583.BITMAP `iso8583:"bitmap,length:64"` // length is the maximum amount of represented elements.
+	SecondBitmap           iso8583.BITMAP `iso8583:"1,length:64"`      // length is the maximum amount of represented elements.
+	PAN                    iso8583.LLVAR  `iso8583:"2,length:2"`       // length is the amount of bytes of the LL part.
+	ProcessingCode         iso8583.VAR    `iso8583:"3,length:6"`
+	Amount                 iso8583.VAR    `iso8583:"4,length:12"`
+	DateTime               iso8583.VAR    `iso8583:"7,length:10"`
+	SystemTraceAuditNumber iso8583.VAR    `iso8583:"11,length:6"`
+	LocalTransactionTime   iso8583.VAR    `iso8583:"12,length:6"`
+	LocalTransactionDate   iso8583.VAR    `iso8583:"13,length:4"`
+	ExpirationDate         iso8583.VAR    `iso8583:"14,length:4"`
+	MerchantType           iso8583.VAR    `iso8583:"18,length:4"`
+	ResponseCode           iso8583.VAR    `iso8583:"39,length:2"`
+	ICC                    iso8583.LLLVAR `iso8583:"55,length:3,encoding:ebcdic/ascii"` // LLL and VAR part use different encoding? Use a / to indicate both
+	SettlementCode         iso8583.VAR    `iso8583:"66,length:1"`
+	MessageNumber          iso8583.VAR    `iso8583:"71,length:4"`
+	TransactionDescriptor  iso8583.VAR    `iso8583:"104,length:100"`
+}
+
+func ReadResp(byt []byte) (PurchaseResponse,error){
+	var resp PurchaseResponse
+
+	_, err :=iso8583.Unmarshal(byt,&resp)
+	if err != nil{
+		return PurchaseResponse{}, err
+	}
+
+	return resp,nil
+}
+```

go.mod

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+module github.com/jattento/go-iso8583
+
+go 1.14
+
+require github.com/stretchr/testify v1.6.1

go.sum

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+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

pkg/bitmap/bitmap.go

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+package bitmap
+
+import (
+	"errors"
+	"fmt"
+	"math"
+)
+
+type Bitmap = map[int]bool
+
+const (
+	_bitmapLength = 8
+	_bitsInByte   = 8
+
+	_firstByteIndex = 0
+	_firstBitOffset = 7
+	_lastBitOffset  = 0
+)
+
+var (
+	// Errors...
+	ErrBitmapISOWrongLength        = errors.New("wrong bitmap length input")
+	ErrBitmapISOBadBitmapPosition  = errors.New("bad bitmap position input")
+	ErrBitmapISOImpossibleBitmap   = errors.New("impossible generate bitmap, lowest and highest limits too far")
+	ErrBitmapISOFirstBitProhibited = errors.New("first bit can be setted manually in input")
+)
+
+// ISO8583FromBytes indicates which elements of a ISO8583 message are present.
+// It receives a 8 byte long ISO8583 bitmap with a position (to indicate if its the first or second).
+// Returns a map[int]bool to allow searching by element.
+func ISO8583FromBytes(b []byte, bitmapPosition int) (presentElements Bitmap, nextBitmapPresent bool, returnErr error) {
+	const nextBitmapIndicator = 1
+
+	// Validate input
+	if len(b) != _bitmapLength {
+		return nil, false,
+			fmt.Errorf("%w: should be %v, but its %v", ErrBitmapISOWrongLength, _bitmapLength, len(b))
+	}
+
+	if bitmapPosition < 1 {
+		return nil, false,
+			fmt.Errorf("%w: should not be lower than 1, but its %v", ErrBitmapISOBadBitmapPosition, bitmapPosition)
+	}
+
+	rawBitmap := FromBytes(b)
+	isoBitmap := make(Bitmap)
+
+	for k, v := range rawBitmap {
+		// Next bitmap indicator is returned separately in the second return value
+		if k != nextBitmapIndicator {
+			isoBitmap[_bitsInByte*_bitmapLength*(bitmapPosition-1)+k] = v
+		}
+	}
+
+	return isoBitmap, rawBitmap[nextBitmapIndicator], nil
+}
+
+// ISO8583ToBytes creates a bitmap in byte format.
+// Map key 1 must not be present.
+func ISO8583ToBytes(b Bitmap, nextBitmapPresent bool) ([]byte, error) {
+	// Find the highest and lowest element in map
+	lowestElement, highestElement := Extremities(b)
+
+	inferiorLimit := 1
+	for checkedLimit := 1; checkedLimit < lowestElement; checkedLimit += 64 {
+		inferiorLimit = checkedLimit
+	}
+
+	superiorLimit := inferiorLimit + 63
+
+	if superiorLimit < highestElement {
+		return nil, fmt.Errorf("%w: lowest limit %v (element %v), highest limit %v (element %v)",
+			ErrBitmapISOImpossibleBitmap, inferiorLimit, lowestElement, superiorLimit, highestElement)
+	}
+
+	if _, exist := b[inferiorLimit]; exist {
+		return nil, fmt.Errorf("%w: position %v", ErrBitmapISOFirstBitProhibited, inferiorLimit)
+	}
+
+	bmap := b
+	bmap[inferiorLimit] = nextBitmapPresent
+
+	if _, exist := bmap[superiorLimit]; !exist {
+		bmap[superiorLimit] = false
+	}
+
+	byt := ToBytes(bmap)
+
+	return byt[len(byt)-_bitmapLength:], nil
+}
+
+// FromBytes given bytes it returns a map[int]bool indicating which biy is on or off. Most left is 1.
+func FromBytes(b []byte) Bitmap {
+	availableElements := make(Bitmap)
+
+	// Iterate over each bit of the input from most left to most right
+	for bytePosition := _firstByteIndex; bytePosition < len(b); bytePosition++ {
+		for bitOffset := _firstBitOffset; bitOffset >= _lastBitOffset; bitOffset-- {
+			// Calculate element position and save in map
+			previousBytesSummary := _bitsInByte * bytePosition
+			bitPosition := _bitsInByte - bitOffset
+
+			availableElements[bitPosition+previousBytesSummary] = hasBitSet(b[bytePosition], uint(bitOffset))
+		}
+	}
+
+	return availableElements
+}
+
+// ToBytes creates a bitmap in []byte format. Most left is 1.
+func ToBytes(b Bitmap) []byte {
+	getPosition := func(byt, bit int) int { return bit + byt*_bitsInByte }
+
+	_, highestElement := Extremities(b)
+
+	bmap := make([]byte, int(math.Ceil(float64(highestElement)/_bitsInByte)))
+	for bytePosition := _firstByteIndex; bytePosition < len(bmap); bytePosition++ {
+		for bitOffset := _firstBitOffset; bitOffset >= _lastBitOffset; bitOffset-- {
+			if isOn, exist := b[getPosition(bytePosition, _bitsInByte-bitOffset)]; exist && isOn {
+				bmap[bytePosition] = setBit(bmap[bytePosition], uint(bitOffset))
+			}
+		}
+	}
+
+	return bmap
+}
+
+// Returns if the indicated bit is on.
+func hasBitSet(n byte, pos uint) bool {
+	val := n & (1 << pos)
+	return val > 0
+}
+
+// Sets the bit at pos in the integer n.
+func setBit(n byte, pos uint) byte {
+	n |= 1 << pos
+	return n
+}
+
+func Extremities(b Bitmap) (low, high int) {
+	firstIteration := true
+	for k := range b {
+		if k > high {
+			high = k
+		}
+		if k < low || firstIteration {
+			low = k
+		}
+		firstIteration = false
+	}
+
+	return low, high
+}