proper multi-error message, try better to find SMTP server, fixes #58

go.mod

@@ -21,7 +21,7 @@ require (
 	gitlab.com/etke.cc/go/logger v1.1.0
 	gitlab.com/etke.cc/go/mxidwc v1.0.0
 	gitlab.com/etke.cc/go/secgen v1.1.1
-	gitlab.com/etke.cc/go/trysmtp v1.1.2
+	gitlab.com/etke.cc/go/trysmtp v1.1.3
 	gitlab.com/etke.cc/go/validator v1.0.6
 	gitlab.com/etke.cc/linkpearl v0.0.0-20230213101923-10ee6beb7577
 	maunium.net/go/mautrix v0.13.0

go.sum

@@ -106,8 +106,8 @@ gitlab.com/etke.cc/go/mxidwc v1.0.0 h1:6EAlJXvs3nU4RaMegYq6iFlyVvLw7JZYnZmNCGMYQ
 gitlab.com/etke.cc/go/mxidwc v1.0.0/go.mod h1:E/0kh45SAN9+ntTG0cwkAEKdaPxzvxVmnjwivm9nmz8=
 gitlab.com/etke.cc/go/secgen v1.1.1 h1:RmKOki725HIhWJHzPtAc9X4YvBneczndchpMgoDkE8w=
 gitlab.com/etke.cc/go/secgen v1.1.1/go.mod h1:3pJqRGeWApzx7qXjABqz2o2SMCNpKSZao/gXVdasqE8=
-gitlab.com/etke.cc/go/trysmtp v1.1.2 h1:Jg+J/zgx77wqJ9J5L5dlKFoQLka6yYTXa2wf+GNhjnQ=
-gitlab.com/etke.cc/go/trysmtp v1.1.2/go.mod h1:lOO7tTdAE0a3ETV3wN3GJ7I1Tqewu7YTpPWaOmTteV0=
+gitlab.com/etke.cc/go/trysmtp v1.1.3 h1:e2EHond77onMaecqCg6mWumffTSEf+ycgj88nbeefDI=
+gitlab.com/etke.cc/go/trysmtp v1.1.3/go.mod h1:lOO7tTdAE0a3ETV3wN3GJ7I1Tqewu7YTpPWaOmTteV0=
 gitlab.com/etke.cc/go/validator v1.0.6 h1:w0Muxf9Pqw7xvF7NaaswE6d7r9U3nB2t2l5PnFMrecQ=
 gitlab.com/etke.cc/go/validator v1.0.6/go.mod h1:Id0SxRj0J3IPhiKlj0w1plxVLZfHlkwipn7HfRZsDts=
 gitlab.com/etke.cc/linkpearl v0.0.0-20230213101923-10ee6beb7577 h1:MXvoTJ9Qp+dWezXR2sXP7HTk9ijXAorEDAy/bxJOxi8=

vendor/gitlab.com/etke.cc/go/trysmtp/.gitlab-ci.yml

@@ -1,11 +0,0 @@
-lint:
-  image: registry.gitlab.com/etke.cc/base
-  script:
-    - golangci-lint run ./...
-
-unit:
-  image: registry.gitlab.com/etke.cc/base
-  script:
-    - go test -coverprofile=cover.out ./...
-    - go tool cover -func=cover.out
-    - rm -f cover.out

vendor/gitlab.com/etke.cc/go/trysmtp/client.go

@@ -41,14 +41,16 @@ func unwrapErrors(errs []error) error {
 		return nil
 	}
 
-	tokens := strings.Repeat("%v; ", len(errs))
-	// make it compatible with < 1.18
-	ierrs := make([]interface{}, len(errs))
-	for _, err := range errs {
-		ierrs = append(ierrs, err)
+	var text strings.Builder
+	last := len(errs) - 1
+	for i := 0; i < len(errs); i++ {
+		text.WriteString(errs[i].Error())
+		if i < last {
+			text.WriteString("; ")
+		}
 	}
 
-	return fmt.Errorf(tokens, ierrs...)
+	return fmt.Errorf(text.String())
 }
 
 func initClient(localname, hostname string) (*smtp.Client, error) {
@@ -60,6 +62,9 @@ func initClient(localname, hostname string) (*smtp.Client, error) {
 	cerrs := []error{}
 	var client *smtp.Client
 	for _, mx := range mxs {
+		if mx.Host == "." {
+			continue // no records case
+		}
 		for _, addr := range SMTPAddrs {
 			client, err = trySMTP(localname, strings.TrimSuffix(mx.Host, "."), addr)
 			if err != nil {
@@ -73,7 +78,6 @@ func initClient(localname, hostname string) (*smtp.Client, error) {
 
 	// If there are no MX records, according to https://datatracker.ietf.org/doc/html/rfc5321#section-5.1,
 	// we're supposed to try talking directly to the host.
-	if len(mxs) == 0 {
 	for _, addr := range SMTPAddrs {
 		client, err = trySMTP(localname, hostname, addr)
 		if err != nil {
@@ -83,7 +87,6 @@ func initClient(localname, hostname string) (*smtp.Client, error) {
 			return client, unwrapErrors(cerrs)
 		}
 	}
-	}
 
 	return nil, unwrapErrors(cerrs)
 }

vendor/modules.txt

@@ -137,7 +137,7 @@ gitlab.com/etke.cc/go/mxidwc
 # gitlab.com/etke.cc/go/secgen v1.1.1
 ## explicit; go 1.19
 gitlab.com/etke.cc/go/secgen
-# gitlab.com/etke.cc/go/trysmtp v1.1.2
+# gitlab.com/etke.cc/go/trysmtp v1.1.3
 ## explicit; go 1.17
 gitlab.com/etke.cc/go/trysmtp
 # gitlab.com/etke.cc/go/validator v1.0.6