identify: remove old code targeting Go 1.17 (#1964)

p2p/protocol/identify/id.go

@@ -42,13 +42,14 @@ const maxPushConcurrency = 32
 // StreamReadTimeout is the read timeout on all incoming Identify family streams.
 var StreamReadTimeout = 60 * time.Second
 
-var (
-	legacyIDSize     = 2 * 1024 // 2k Bytes
-	signedIDSize     = 8 * 1024 // 8K
-	maxMessages      = 10
-	defaultUserAgent = "github.com/libp2p/go-libp2p"
+const (
+	legacyIDSize = 2 * 1024 // 2k Bytes
+	signedIDSize = 8 * 1024 // 8K
+	maxMessages  = 10
 )
 
+var defaultUserAgent = "github.com/libp2p/go-libp2p"
+
 type addPeerHandlerReq struct {
 	rp   peer.ID
 	resp chan *peerHandler

p2p/protocol/identify/id_go117.go

@@ -1,22 +0,0 @@
-//go:build !go1.18
-
-package identify
-
-import (
-	"fmt"
-	"runtime/debug"
-)
-
-func init() {
-	bi, ok := debug.ReadBuildInfo()
-	// ok will only be true if this is built as a dependency of another module
-	if !ok {
-		return
-	}
-	version := bi.Main.Version
-	if version == "(devel)" {
-		defaultUserAgent = bi.Main.Path
-	} else {
-		defaultUserAgent = fmt.Sprintf("%s@%s", bi.Main.Path, bi.Main.Version)
-	}
-}

p2p/protocol/identify/id_go118.go → p2p/protocol/identify/user_agent.go

@@ -1,5 +1,3 @@
-//go:build go1.18
-
 package identify
 
 import (