Fix documentation/comment typos

This patch fixes a variety of typos in documentation and comments, found
by running `codespell`.

internal/aliases/aliases.go

@@ -86,7 +86,7 @@ type Recipient struct {
 	Type RType
 }
 
-// RType represents a recipient type, see the contants below for valid values.
+// RType represents a recipient type, see the constants below for valid values.
 type RType string
 
 // Valid recipient types.

internal/domaininfo/domaininfo_test.go

@@ -90,7 +90,7 @@ func TestNewDomain(t *testing.T) {
 	for _, c := range cases {
 		// The other tests do an incoming check first, so new domains would get
 		// created via that path. We switch the order here to exercise that
-		// OutgoingSecLevel also handles new domains successfuly.
+		// OutgoingSecLevel also handles new domains successfully.
 		if !db.OutgoingSecLevel(tr, c.domain, c.level) {
 			t.Errorf("domain %q not allowed (out) at %s", c.domain, c.level)
 		}

internal/dovecot/dovecot.go

@@ -239,7 +239,7 @@ func write(conn *textproto.Conn, msg string) error {
 }
 
 // isUsernameSafe to use in the dovecot protocol?
-// Unfotunately dovecot's protocol is not very robust wrt. whitespace,
+// Unfortunately dovecot's protocol is not very robust wrt. whitespace,
 // so we need to be careful.
 func isUsernameSafe(user string) bool {
 	for _, r := range user {

internal/expvarom/expvarom.go

@@ -19,7 +19,7 @@
 // and it is possible that it will change in the future.
 //
 // Backwards compatibility is NOT guaranteed, until the format is fully
-// standarized.
+// standardized.
 package expvarom
 
 import (

internal/localrpc/localrpc.go

@@ -2,7 +2,7 @@
 //
 // This is a simple RPC package that uses a line-oriented protocol for
 // encoding and decoding, and Unix sockets for transport. It is meant to be
-// used for lightweight occassional communication between processes on the
+// used for lightweight occasional communication between processes on the
 // same machine.
 package localrpc
 

internal/nettrace/trace.go

@@ -301,7 +301,7 @@ func (tr *trace) IsError() bool {
 // We keep this many buckets of finished traces.
 const nBuckets = 8
 
-// Buckets to use. Lenght must match nBuckets.
+// Buckets to use. Length must match nBuckets.
 // "Traces with a latency >= $duration".
 var buckets = []time.Duration{
 	time.Duration(0),

internal/smtpsrv/conn.go

@@ -845,7 +845,7 @@ func (c *Conn) runPostDataHook(data []byte) ([]byte, bool, error) {
 	cmd.Stdin = bytes.NewReader(data)
 
 	// Prepare the environment, copying some common variables so the hook has
-	// someting reasonable, and then setting the specific ones for this case.
+	// something reasonable, and then setting the specific ones for this case.
 	for _, v := range strings.Fields("USER PWD SHELL PATH") {
 		cmd.Env = append(cmd.Env, v+"="+os.Getenv(v))
 	}

internal/sts/sts_test.go

@@ -550,7 +550,7 @@ func TestHTTPGet(t *testing.T) {
 		t.Errorf("content type != text/plain was allowed: got %q, %v", raw, err)
 	}
 
-	// Invalid (unparseable) media type.
+	// Invalid (unparsable) media type.
 	srv4 := httptest.NewServer(
 		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			w.Header().Set("Content-Type", "invalid/content/type")