fix: UserAgent based on build info

p2pd/main.go

@@ -126,7 +126,7 @@ func main() {
 	var c config.Config
 	defaultCtx := context.Background() // context used for all streams opened by this daemon
 	opts := []libp2p.Option{
-		libp2p.UserAgent("p2pd/0.1"),
+		libp2p.UserAgent(p2pd.UserAgent()),
 		libp2p.DefaultTransports,
 	}
 

version.go

@@ -0,0 +1,53 @@
+package p2pd
+
+import (
+	"fmt"
+	"runtime/debug"
+	"strings"
+)
+
+const name = "learning@home"
+
+var defaultUserAgent string
+
+func init() {
+	bi, ok := debug.ReadBuildInfo()
+	if !ok {
+		defaultUserAgent = name + "/unknown-build"
+		return
+	}
+
+	version := bi.Main.Version
+	if version == "" {
+		version = "(unknown)"
+	}
+
+	revision, dirty := "", ""
+	for _, bs := range bi.Settings {
+		switch bs.Key {
+		case "vcs.revision":
+			if len(bs.Value) >= 9 {
+				revision = bs.Value[:9]
+			} else {
+				revision = bs.Value
+			}
+		case "vcs.modified":
+			if bs.Value == "true" {
+				dirty = "-dirty"
+			}
+		}
+	}
+
+	if strings.HasPrefix(version, "v") {
+		defaultUserAgent = fmt.Sprintf("%s/%s", name, version)
+	} else if revision != "" {
+		defaultUserAgent = fmt.Sprintf("%s/%s%s", name, revision, dirty)
+	} else {
+		defaultUserAgent = fmt.Sprintf("%s@%s", bi.Main.Path, version)
+	}
+}
+
+// UserAgent returns the dynamically generated user agent string.
+func UserAgent() string {
+	return defaultUserAgent
+}