Make PackDomainName return error if the root label doesn't fit (#1702)

fcelda · web-flow · commit c37687222bb1 · 2026-01-22T09:22:52.000+01:00
* add PackDomainName tests for buffer size

* make PackDomainName fail if root label doesn't fit

* review: coding style

* review: remove unit test
diff --git a/msg.go b/msg.go
@@ -338,11 +338,13 @@ loop:
 		return off + 2, nil
 	}
 
+	// Trailing root label
 	if off < len(msg) {
 		msg[off] = 0
+		return off + 1, nil
 	}
 
-	return off + 1, nil
+	return off, ErrBuf
 }
 
 // isRootLabel returns whether s or bs, from off to end, is the root

Original file line number	Diff line number	Diff line change
`@@ -338,11 +338,13 @@ loop:`
`338`	`338`	`return off + 2, nil`
`339`	`339`	`}`
`340`	`340`
	`341`	`+ // Trailing root label`
`341`	`342`	`if off < len(msg) {`
`342`	`343`	`msg[off] = 0`
	`344`	`+ return off + 1, nil`
`343`	`345`	`}`
`344`	`346`
`345`		`- return off + 1, nil`
	`347`	`+ return off, ErrBuf`
`346`	`348`	`}`
`347`	`349`
`348`	`350`	`// isRootLabel returns whether s or bs, from off to end, is the root`