Initial commit

checker/rule.go

@@ -0,0 +1,103 @@
+package checker
+
+import (
+	"context"
+	"fmt"
+
+	sdk "git.happydns.org/checker-sdk-go/checker"
+)
+
+func Rule() sdk.CheckRule {
+	return &smtpRule{}
+}
+
+type smtpRule struct{}
+
+func (r *smtpRule) Name() string {
+	return "smtp_server"
+}
+
+func (r *smtpRule) Description() string {
+	return "Checks MX discovery, SMTP connectivity, STARTTLS, PTR/FCrDNS and mail-acceptance posture for an email-receiving domain"
+}
+
+func (r *smtpRule) Evaluate(ctx context.Context, obs sdk.ObservationGetter, opts sdk.CheckerOptions) []sdk.CheckState {
+	var data SMTPData
+	if err := obs.Get(ctx, ObservationKeySMTP, &data); err != nil {
+		return []sdk.CheckState{{
+			Status:  sdk.StatusError,
+			Message: fmt.Sprintf("failed to load SMTP observation: %v", err),
+			Code:    "smtp.observation_error",
+		}}
+	}
+
+	// Null-MX is a *declared* refusal of mail; it's an INFO, not a fail.
+	if data.MX.NullMX {
+		return []sdk.CheckState{{
+			Status:  sdk.StatusInfo,
+			Message: "Domain refuses all email via null MX (RFC 7505).",
+			Code:    CodeNullMX,
+			Meta: map[string]any{
+				"null_mx": true,
+			},
+		}}
+	}
+
+	issues := append([]Issue(nil), data.Issues...)
+
+	// Fold related TLS observations so cert/chain problems show up on the
+	// SMTP service page without requiring the user to open a separate
+	// report.
+	related, _ := obs.GetRelated(ctx, TLSRelatedKey)
+	issues = append(issues, tlsIssuesFromRelated(related)...)
+
+	if len(issues) == 0 {
+		return []sdk.CheckState{{
+			Status:  sdk.StatusOK,
+			Message: fmt.Sprintf("SMTP operational (%d MX, %d endpoints, TLS=%v)", len(data.MX.Records), len(data.Endpoints), data.Coverage.AllSTARTTLS),
+			Code:    "smtp.ok",
+			Meta: map[string]any{
+				"has_ipv4":        data.Coverage.HasIPv4,
+				"has_ipv6":        data.Coverage.HasIPv6,
+				"any_starttls":    data.Coverage.AnySTARTTLS,
+				"all_starttls":    data.Coverage.AllSTARTTLS,
+				"all_accept_mail": data.Coverage.AllAcceptMail,
+				"mx_count":        len(data.MX.Records),
+				"endpoint_count":  len(data.Endpoints),
+			},
+		}}
+	}
+
+	out := make([]sdk.CheckState, 0, len(issues))
+	for _, is := range issues {
+		status := sdk.StatusInfo
+		switch is.Severity {
+		case SeverityCrit:
+			status = sdk.StatusCrit
+		case SeverityWarn:
+			status = sdk.StatusWarn
+		}
+		subject := is.Endpoint
+		if subject == "" {
+			subject = is.Target
+		}
+		meta := map[string]any{}
+		if is.Fix != "" {
+			meta["fix"] = is.Fix
+		}
+		if is.Endpoint != "" {
+			meta["endpoint"] = is.Endpoint
+		}
+		if is.Target != "" {
+			meta["target"] = is.Target
+		}
+		out = append(out, sdk.CheckState{
+			Status:  status,
+			Message: is.Message,
+			Code:    is.Code,
+			Subject: subject,
+			Meta:    meta,
+		})
+	}
+	return out
+}