From 8e784438c7ebb77eb903c964192012d8a0826d02 Mon Sep 17 00:00:00 2001
From: Neil Alexander <neilalexander@users.noreply.github.com>
Date: Fri, 7 Dec 2018 22:20:11 +0000
Subject: [PATCH] Imprint build name and version number if available

---
 build                 |  5 +++--
 src/yggdrasil/core.go | 21 +++++++++++++++++++++
 yggdrasil.go          |  5 +++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/build b/build
index c07e5eac..2e7c20cc 100755
--- a/build
+++ b/build
@@ -14,10 +14,11 @@ go get -d -v yggdrasil
 for file in *.go ; do
   echo "Building: $file"
   #go build $@ $file
+  IMPRINT="-X yggdrasil.buildName=$(sh contrib/semver/name.sh) -X yggdrasil.buildVersion=$(sh contrib/semver/version.sh)"
   if [ $DEBUG ]; then
-    go build -tags debug -v $file
+    go build -ldflags="$IMPRINT" -tags debug -v $file
   else
-    go build -ldflags="-s -w" -v $file
+    go build -ldflags="$IMPRINT -s -w" -v $file
   fi
   if [ $UPX ]; then
     upx --brute ${file%.go}
diff --git a/src/yggdrasil/core.go b/src/yggdrasil/core.go
index 706b8aa3..54f1820c 100644
--- a/src/yggdrasil/core.go
+++ b/src/yggdrasil/core.go
@@ -12,6 +12,9 @@ import (
 	"yggdrasil/defaults"
 )
 
+var buildName string
+var buildVersion string
+
 // The Core object represents the Yggdrasil node. You should create a Core
 // object for each Yggdrasil node you plan to run.
 type Core struct {
@@ -59,6 +62,24 @@ func (c *Core) init(bpub *boxPubKey,
 	c.tun.init(c)
 }
 
+// Get the current build name. This is usually injected if built from git,
+// or returns "unknown" otherwise.
+func GetBuildName() string {
+	if buildName == "" {
+		return "unknown"
+	}
+	return buildName
+}
+
+// Get the current build version. This is usually injected if built from git,
+// or returns "unknown" otherwise.
+func GetBuildVersion() string {
+	if buildVersion == "" {
+		return "unknown"
+	}
+	return buildVersion
+}
+
 // Starts up Yggdrasil using the provided NodeConfig, and outputs debug logging
 // through the provided log.Logger. The started stack will include TCP and UDP
 // sockets, a multicast discovery socket, an admin socket, router, switch and
diff --git a/yggdrasil.go b/yggdrasil.go
index 5244a8ec..d326d18e 100644
--- a/yggdrasil.go
+++ b/yggdrasil.go
@@ -100,10 +100,15 @@ func main() {
 	normaliseconf := flag.Bool("normaliseconf", false, "use in combination with either -useconf or -useconffile, outputs your configuration normalised")
 	confjson := flag.Bool("json", false, "print configuration from -genconf or -normaliseconf as JSON instead of HJSON")
 	autoconf := flag.Bool("autoconf", false, "automatic mode (dynamic IP, peer with IPv6 neighbors)")
+	version := flag.Bool("version", false, "prints the version of this build")
 	flag.Parse()
 
 	var cfg *nodeConfig
 	switch {
+	case *version:
+		fmt.Println("Build name:", yggdrasil.GetBuildName())
+		fmt.Println("Build version:", yggdrasil.GetBuildVersion())
+		os.Exit(0)
 	case *autoconf:
 		// Use an autoconf-generated config, this will give us random keys and
 		// port numbers, and will use an automatically selected TUN/TAP interface.