Add basic checking of mx records for mailto links

tomtom5152 · tomtom5152 · commit c3ff3fe7972e · 2017-08-20T14:08:15.000+01:00
Helps ensure that the domain is registered and at least partially configured to recieve email.
diff --git a/htmltest/check-link.go b/htmltest/check-link.go
@@ -10,6 +10,7 @@ import (
 	"os"
 	"path"
 	"strings"
+	"net"
 )
 
 func (hT *HTMLTest) checkLink(document *htmldoc.Document, node *html.Node) {
@@ -347,6 +348,34 @@ func (hT *HTMLTest) checkMailto(ref *htmldoc.Reference) {
 		})
 		return
 	}
+	domain := strings.Split(ref.URL.Opaque, "@")[1]
+	_, err := net.LookupMX(domain)
+	if err != nil {
+		if dnserr, ok := err.(*net.DNSError); ok {
+			switch dnserr.Err {
+			case "no such host":
+				hT.issueStore.AddIssue(issues.Issue{
+					Level:     issues.LevelError,
+					Message:   "domain contains no valid MX records",
+					Reference: ref,
+				})
+				break
+			default:
+				hT.issueStore.AddIssue(issues.Issue{
+					Level:     issues.LevelError,
+					Message:   "unable to perform LookupMX, unkown error",
+					Reference: ref,
+				})
+			}
+		} else {
+			hT.issueStore.AddIssue(issues.Issue{
+				Level:     issues.LevelWarning,
+				Message:   "unable to perform LookupMX, unkown error",
+				Reference: ref,
+			})
+		}
+		return
+	}
 }
 
 func (hT *HTMLTest) checkTel(ref *htmldoc.Reference) {
diff --git a/htmltest/check-link_test.go b/htmltest/check-link_test.go
@@ -369,13 +369,20 @@ func TestMailtoBlank(t *testing.T) {
 	tExpectIssue(t, hT, "mailto is empty", 1)
 }
 
-func TestMailtoInvalid(t *testing.T) {
+func TestMailtoInvalidFormat(t *testing.T) {
 	// fails for invalid mailto links
 	hT := tTestFile("fixtures/links/invalid_mailto_link.html")
 	tExpectIssueCount(t, hT, 1)
 	tExpectIssue(t, hT, "contains an invalid email address", 1)
 }
 
+func TestMailtoInvalidMx(t *testing.T) {
+	// fails for invalid mailto links
+	hT := tTestFile("fixtures/links/invalid_mailto_mx.html")
+	tExpectIssueCount(t, hT, 1)
+	tExpectIssue(t, hT, "domain contains no valid MX records", 1)
+}
+
 func TestMailtoIgnore(t *testing.T) {
 	// ignores mailto links when told to
 	hT := tTestFileOpts("fixtures/links/blank_mailto_link.html",
diff --git a/htmltest/fixtures/links/invalid_mailto_mx.html b/htmltest/fixtures/links/invalid_mailto_mx.html
@@ -0,0 +1,9 @@
+<html>
+
+<body>
+
+<a href="mailto:octocat@mxfail.test">Meow me</a>
+
+</body>
+
+</html>

-Original file line number
+Diff line change
@@ @@ -0,0 +1,9 @@ @@
 +<html>
++
 +<body>
++
 +<a href="mailto:[email protected]">Meow me</a>
++
 +</body>
++
 +</html>