From b13f65a9ab18c01ee97090c73798d01c83c6e7c6 Mon Sep 17 00:00:00 2001
From: Aditya Kulkarni <adityapk@gmail.com>
Date: Mon, 4 May 2020 12:17:14 -0700
Subject: [PATCH] Add params serving

---
 cmd/server/main.go          |  6 ++++++
 common/downloadhandler.go   | 41 +++++++++++++++++++++++++++++++++++++
 common/prometheusmetrics.go | 20 ++++++++++++++----
 3 files changed, 63 insertions(+), 4 deletions(-)
 create mode 100644 common/downloadhandler.go

diff --git a/cmd/server/main.go b/cmd/server/main.go
index 40fe0be..08f1c27 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -47,6 +47,8 @@ func init() {
 	promRegistry.MustRegister(metrics.TotalErrors)
 	promRegistry.MustRegister(metrics.TotalBlocksServedConter)
 	promRegistry.MustRegister(metrics.SendTransactionsCounter)
+	promRegistry.MustRegister(metrics.TotalSaplingParamsCounter)
+	promRegistry.MustRegister(metrics.TotalSproutParamsCounter)
 }
 
 // TODO stream logging
@@ -255,6 +257,10 @@ func main() {
 		log.Fatal(http.ListenAndServe(":2234", nil))
 	}()
 
+	// Start the download params handler
+	log.Infof("Starting params handler")
+	go common.ParamsDownloadHandler(metrics)
+
 	log.Infof("Starting gRPC server on %s", opts.bindAddr)
 
 	err = server.Serve(listener)
diff --git a/common/downloadhandler.go b/common/downloadhandler.go
new file mode 100644
index 0000000..620de9e
--- /dev/null
+++ b/common/downloadhandler.go
@@ -0,0 +1,41 @@
+package common
+
+import (
+	"net/http"
+	"strings"
+)
+
+var (
+	metrics *PrometheusMetrics
+)
+
+// Handle http(s) downloads for zcash params
+func paramsHandler(w http.ResponseWriter, req *http.Request) {
+	if strings.HasSuffix(req.URL.Path, "sapling-output.params") {
+		metrics.TotalSaplingParamsCounter.Inc()
+		http.Redirect(w, req, "https://z.cash/downloads/sapling-output.params", 301)
+		return
+	}
+
+	if strings.HasSuffix(req.URL.Path, "sapling-spend.params") {
+		http.Redirect(w, req, "https://z.cash/downloads/sapling-spend.params", 301)
+		return
+	}
+
+	if strings.HasSuffix(req.URL.Path, "sprout-groth16.params") {
+		metrics.TotalSproutParamsCounter.Inc()
+		http.Redirect(w, req, "https://z.cash/downloads/sprout-groth16.params", 301)
+		return
+	}
+
+	http.Error(w, "Not Found", 404)
+}
+
+// ParamsDownloadHandler Listens on port 8090 for download requests for params
+func ParamsDownloadHandler(prommetrics *PrometheusMetrics) {
+	metrics = prommetrics
+	http.HandleFunc("/params/", paramsHandler)
+
+	println("Handling at params")
+	http.ListenAndServe(":8090", nil)
+}
diff --git a/common/prometheusmetrics.go b/common/prometheusmetrics.go
index 62989c6..5e55dcf 100644
--- a/common/prometheusmetrics.go
+++ b/common/prometheusmetrics.go
@@ -4,10 +4,12 @@ import "github.com/prometheus/client_golang/prometheus"
 
 // PrometheusMetrics is a list of collected Prometheus Counters and Guages that will be exported
 type PrometheusMetrics struct {
-	LatestBlockCounter      prometheus.Counter
-	TotalBlocksServedConter prometheus.Counter
-	SendTransactionsCounter prometheus.Counter
-	TotalErrors             prometheus.Counter
+	LatestBlockCounter        prometheus.Counter
+	TotalBlocksServedConter   prometheus.Counter
+	SendTransactionsCounter   prometheus.Counter
+	TotalErrors               prometheus.Counter
+	TotalSaplingParamsCounter prometheus.Counter
+	TotalSproutParamsCounter  prometheus.Counter
 }
 
 func GetPrometheusMetrics() *PrometheusMetrics {
@@ -32,5 +34,15 @@ func GetPrometheusMetrics() *PrometheusMetrics {
 		Help: "Total number of errors seen by lightwalletd",
 	})
 
+	m.TotalSaplingParamsCounter = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "params_sapling_total",
+		Help: "Total number of params downloads for sapling params",
+	})
+
+	m.TotalSproutParamsCounter = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "params_sprout_total",
+		Help: "Total number of params downloasd for sprout params",
+	})
+
 	return m
 }