Receipt validation on server side

receiptvalidator.go

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"github.com/gorilla/mux"
	"log"
	"net/http"
)

// ReceiptData contains receipt data received from client
type ReceiptData struct {
	ReceiptBase64	string	`json:"receipt"`
	IsSandBox 	bool   	`json:"sandbox"`
}

// AppStoreReceiptData contains receipt data sent to App Store
type AppStoreReceiptData struct {
	ReceiptData	string 	`json:"receipt-data"`
}

// ReceiptValidationResult contains validation result returned to client
type ReceiptValidationResult struct {
	Result		int
	Environment	string
}

func main() {
	router := mux.NewRouter()

	router.HandleFunc("/validatereceipt", func(writer http.ResponseWriter, r *http.Request) {

		var receipt ReceiptData

		// Read request body
		decoder := json.NewDecoder(r.Body)
		error := decoder.Decode(&receipt)

		if error != nil {
			http.Error(writer, error.Error(), http.StatusBadRequest)
			return
		}

		// Decide which App Store URL to use (Sandbox or Production)
		var appStoreURL string

		if receipt.IsSandBox {
			appStoreURL = "https://sandbox.itunes.apple.com/verifyReceipt"
		} else {
			appStoreURL = "https://buy.itunes.apple.com/verifyReceipt"
		}

		// Encode json data for App Store
		buffer := new(bytes.Buffer)
		appStoreReceiptData := AppStoreReceiptData{ReceiptData:receipt.ReceiptBase64}
		error = json.NewEncoder(buffer).Encode(appStoreReceiptData)

		// Send receipt to App Store
		response, error := http.Post(appStoreURL, "application/json", buffer)

		if error != nil {
			log.Fatalln(error)
		}

		// Decode App Store response
		var receiptValidationResult ReceiptValidationResult
		json.NewDecoder(response.Body).Decode(&receiptValidationResult)

		fmt.Printf("Receipt validated with result %d for environment: %s", receiptValidationResult.Result, receiptValidationResult.Environment)

		// Return result to client
		writer.Header().Set("Content-Type", "application/json")
		json.NewEncoder(writer).Encode(receiptValidationResult)

	}).Methods("POST")

	error := http.ListenAndServe("localhost:8080", router)

	if error != nil {
		fmt.Print(error)
	}
}