snapshot of https://github.com/ory/kratos.git (master, 2026-09-15; blobs > 131072B omitted)

courier/smtp_channel.go

@@ -0,0 +1,201 @@
+// Copyright © 2023 Ory Corp
+// SPDX-License-Identifier: Apache-2.0
+
+package courier
+
+import (
+	"context"
+	"net"
+	stdmail "net/mail"
+	"net/textproto"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/pkg/errors"
+	semconv "go.opentelemetry.io/otel/semconv/v1.20.0"
+	"go.opentelemetry.io/otel/trace"
+
+	"github.com/ory/herodot"
+	"github.com/ory/kratos/courier/template"
+	"github.com/ory/kratos/driver/config"
+	"github.com/ory/kratos/x"
+	"github.com/ory/mail/v3"
+	"github.com/ory/x/otelx"
+)
+
+type (
+	SMTPChannel struct {
+		smtpClient *SMTPClient
+		d          Dependencies
+
+		newEmailTemplateFromMessage func(d template.Dependencies, msg Message) (EmailTemplate, error)
+	}
+)
+
+var _ Channel = new(SMTPChannel)
+
+func NewSMTPChannel(deps Dependencies, cfg *config.SMTPConfig) (*SMTPChannel, error) {
+	return NewSMTPChannelWithCustomTemplates(deps, cfg, NewEmailTemplateFromMessage)
+}
+
+func NewSMTPChannelWithCustomTemplates(deps Dependencies, cfg *config.SMTPConfig, newEmailTemplateFromMessage func(d template.Dependencies, msg Message) (EmailTemplate, error)) (*SMTPChannel, error) {
+	smtpClient, err := NewSMTPClient(deps, cfg)
+	if err != nil {
+		return nil, err
+	}
+	return &SMTPChannel{
+		smtpClient:                  smtpClient,
+		d:                           deps,
+		newEmailTemplateFromMessage: newEmailTemplateFromMessage,
+	}, nil
+}
+
+func (c *SMTPChannel) ID() string {
+	return "email"
+}
+
+func (c *SMTPChannel) Dispatch(ctx context.Context, msg Message) (err error) {
+	ctx, span := c.d.Tracer(ctx).Tracer().Start(ctx, "courier.SMTPChannel.Dispatch")
+	defer otelx.End(span, &err)
+
+	if c.smtpClient.Host == "" {
+		return errors.WithStack(herodot.ErrInternalServerError().WithErrorf("Courier tried to deliver an email but %s is not set!", config.ViperKeyCourierSMTPURL))
+	}
+
+	channels, err := c.d.CourierConfig().CourierChannels(ctx)
+	if err != nil {
+		return err
+	}
+
+	var cfg *config.SMTPConfig
+	for _, channel := range channels {
+		if channel.ID == "email" && channel.SMTPConfig != nil {
+			cfg = channel.SMTPConfig
+			break
+		}
+	}
+
+	if cfg == nil {
+		return errors.WithStack(herodot.ErrInternalServerError().WithErrorf("Courier tried to deliver an email but SMTP channel is misconfigured."))
+	}
+
+	// Re-validate the recipient read from the database: a value that is neither
+	// RFC 5322-valid nor injection-safe per x.IsEmailAddress is abandoned
+	// rather than placed in an SMTP command or header.
+	_, rfcErr := stdmail.ParseAddress(msg.Recipient)
+	if rfcErr != nil && !x.IsEmailAddress(msg.Recipient) {
+		if err := c.d.CourierPersister().SetMessageStatus(ctx, msg.ID, MessageStatusAbandoned); err != nil {
+			c.d.Logger().WithError(err).Error(`Unable to set the message status to "abandoned".`)
+			return errors.WithStack(err)
+		}
+		return errors.WithStack(herodot.ErrInternalServerError().
+			WithReasonf("courier: email recipient for message %s is not a valid email address", msg.ID))
+	}
+
+	gm := mail.NewMessage()
+	if cfg.FromName == "" {
+		gm.SetHeader("From", cfg.FromAddress)
+	} else {
+		gm.SetAddressHeader("From", cfg.FromAddress, cfg.FromName)
+	}
+
+	gm.SetHeader("To", msg.Recipient)
+	gm.SetHeader("Subject", msg.Subject)
+
+	headers := cfg.Headers
+	for k, v := range headers {
+		gm.SetHeader(k, v)
+	}
+
+	gm.SetBody("text/plain", msg.Body)
+
+	logger := c.d.Logger().
+		WithField("smtp_server", net.JoinHostPort(c.smtpClient.Host, strconv.Itoa(c.smtpClient.Port))).
+		WithField("smtp_ssl_enabled", c.smtpClient.SSL).
+		WithField("message_from", cfg.FromAddress).
+		WithField("message_id", msg.ID).
+		WithField("message_nid", msg.NID).
+		WithField("message_type", msg.Type).
+		WithField("message_template_type", msg.TemplateType).
+		WithField("message_subject", msg.Subject).
+		WithField("trace_id", span.SpanContext().TraceID())
+
+	tmpl, err := c.newEmailTemplateFromMessage(c.d, msg)
+	if err != nil {
+		logger.
+			WithError(err).Error(`Unable to get email template from message.`)
+	} else if htmlBody, err := tmpl.EmailBody(ctx); err != nil {
+		logger.
+			WithError(err).Error(`Unable to get email body from template.`)
+	} else {
+		gm.AddAlternative("text/html", htmlBody)
+	}
+
+	dialCtx, dialSpan := c.d.Tracer(ctx).Tracer().Start(ctx, "courier.SMTPChannel.Dispatch.Dial", trace.WithAttributes(
+		semconv.NetPeerName(c.smtpClient.Host),
+		semconv.NetPeerPort(c.smtpClient.Port),
+		semconv.NetProtocolName("smtp"),
+	))
+	snd, err := c.smtpClient.Dial(dialCtx)
+	otelx.End(dialSpan, &err)
+
+	if err != nil {
+		logger.
+			WithError(err).
+			WithField("smtp_host", c.smtpClient.Host).
+			WithField("smtp_port", c.smtpClient.Port).
+			Error("Unable to dial SMTP connection.")
+		return errors.WithStack(herodot.ErrInternalServerError().
+			WithError(err.Error()).WithReason("failed to send email via smtp"))
+	}
+	defer func() { _ = snd.Close() }()
+
+	sendCtx, sendSpan := c.d.Tracer(ctx).Tracer().Start(ctx, "courier.SMTPChannel.Dispatch.Send")
+	if rfcErr == nil {
+		// mail.Send derives the envelope from the To/Cc/Bcc headers, so Cc/Bcc
+		// configured via courier.smtp.headers are delivered.
+		err = mail.Send(sendCtx, snd, gm)
+	} else {
+		// A non-RFC recipient bypasses mail.Send's strict header re-parse with
+		// an explicit envelope; Cc/Bcc headers are not delivered on this path.
+		for k := range headers {
+			if strings.EqualFold(k, "Cc") || strings.EqualFold(k, "Bcc") {
+				logger.Warnf("Configured %q recipients are not delivered for a non-RFC email address.", k)
+			}
+		}
+		err = snd.Send(sendCtx, cfg.FromAddress, []string{msg.Recipient}, gm)
+	}
+	otelx.End(sendSpan, &err)
+
+	if err != nil {
+		logger.
+			WithError(err).
+			Error("Unable to send email using SMTP connection.")
+
+		var protoErr *textproto.Error
+		var mailErr *mail.SendError
+
+		switch {
+		case errors.As(err, &mailErr) && errors.As(mailErr.Cause, &protoErr) && protoErr.Code >= 500:
+			fallthrough
+		case errors.As(err, &protoErr) && protoErr.Code >= 500:
+			// See https://en.wikipedia.org/wiki/List_of_SMTP_server_return_codes
+			// If the SMTP server responds with 5xx, sending the message should not be retried (without changing something about the request)
+			if err := c.d.CourierPersister().SetMessageStatus(ctx, msg.ID, MessageStatusAbandoned); err != nil {
+				logger.
+					WithError(err).
+					Error(`Unable to reset the retried message's status to "abandoned".`)
+				return errors.WithStack(err)
+			}
+		}
+
+		return errors.WithStack(herodot.ErrInternalServerError().
+			WithError(err.Error()).WithReason("failed to send email via smtp"))
+	}
+
+	dispatchDuration := time.Since(msg.CreatedAt).Milliseconds()
+	logger.WithField("dispatch_duration_ms", dispatchDuration).Debug("Courier sent out message.")
+
+	return nil
+}