Add email notification plugin. (#1013)

* Add email notification plugin.
* Add plugin binary to gitignore

Signed-off-by: Shivam Sandbhor <shivam.sandbhor@gmail.com>

plugins/notifications/email/main.go

@@ -0,0 +1,122 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"github.com/crowdsecurity/crowdsec/pkg/protobufs"
+	"github.com/hashicorp/go-hclog"
+	plugin "github.com/hashicorp/go-plugin"
+	mail "github.com/xhit/go-simple-mail/v2"
+	"gopkg.in/yaml.v2"
+)
+
+var logger hclog.Logger = hclog.New(&hclog.LoggerOptions{
+	Name:       "email-plugin",
+	Level:      hclog.LevelFromString("DEBUG"),
+	Output:     os.Stderr,
+	JSONFormat: true,
+})
+
+var AuthStringToType map[string]mail.AuthType = map[string]mail.AuthType{
+	"none":    mail.AuthNone,
+	"crammd5": mail.AuthCRAMMD5,
+	"login":   mail.AuthLogin,
+	"plain":   mail.AuthPlain,
+}
+
+var EncryptionStringToType map[string]mail.Encryption = map[string]mail.Encryption{
+	"ssltls": mail.EncryptionSTARTTLS,
+	"none":   mail.EncryptionNone,
+}
+
+type PluginConfig struct {
+	Name     string  `yaml:"name"`
+	LogLevel *string `yaml:"log_level"`
+
+	SMTPHost       string   `yaml:"smtp_host"`
+	SMTPPort       int      `yaml:"smtp_port"`
+	SMTPUsername   string   `yaml:"smtp_username"`
+	SMTPPassword   string   `yaml:"smtp_password"`
+	SenderEmail    string   `yaml:"sender_email"`
+	ReceiverEmails []string `yaml:"receiver_emails"`
+	EmailSubject   string   `yaml:"email_subject"`
+	EncryptionType string   `yaml:"encryption_type"`
+	AuthType       string   `yaml:"auth_type"`
+}
+
+type EmailPlugin struct {
+	ConfigByName map[string]PluginConfig
+}
+
+func (n *EmailPlugin) Configure(ctx context.Context, config *protobufs.Config) (*protobufs.Empty, error) {
+	d := PluginConfig{}
+	if err := yaml.Unmarshal(config.Config, &d); err != nil {
+		return nil, err
+	}
+	n.ConfigByName[d.Name] = d
+	return &protobufs.Empty{}, nil
+}
+
+func (n *EmailPlugin) Notify(ctx context.Context, notification *protobufs.Notification) (*protobufs.Empty, error) {
+	if _, ok := n.ConfigByName[notification.Name]; !ok {
+		return nil, fmt.Errorf("invalid plugin config name %s", notification.Name)
+	}
+	cfg := n.ConfigByName[notification.Name]
+	if cfg.LogLevel != nil && *cfg.LogLevel != "" {
+		logger.SetLevel(hclog.LevelFromString(*cfg.LogLevel))
+	} else {
+		logger.SetLevel(hclog.Info)
+	}
+	logger = logger.Named(cfg.Name)
+	logger.Debug("got notification")
+
+	server := mail.NewSMTPClient()
+	server.Host = cfg.SMTPHost
+	server.Port = cfg.SMTPPort
+	server.Username = cfg.SMTPUsername
+	server.Password = cfg.SMTPPassword
+	server.Encryption = EncryptionStringToType[cfg.EncryptionType]
+	server.Authentication = AuthStringToType[cfg.AuthType]
+
+	logger.Debug("making smtp connection")
+	smtpClient, err := server.Connect()
+	if err != nil {
+		return &protobufs.Empty{}, err
+	}
+	logger.Debug("smtp connection done")
+
+	email := mail.NewMSG()
+	email.SetFrom(fmt.Sprintf("From <%s>", cfg.SenderEmail)).
+		AddTo(cfg.ReceiverEmails...).
+		SetSubject(cfg.EmailSubject)
+	email.SetBody(mail.TextHTML, notification.Text)
+
+	err = email.Send(smtpClient)
+	if err != nil {
+		return &protobufs.Empty{}, err
+	} else {
+		logger.Info(fmt.Sprintf("sent email to %v", cfg.ReceiverEmails))
+	}
+	return &protobufs.Empty{}, nil
+}
+
+func main() {
+	var handshake = plugin.HandshakeConfig{
+		ProtocolVersion:  1,
+		MagicCookieKey:   "CROWDSEC_PLUGIN_KEY",
+		MagicCookieValue: os.Getenv("CROWDSEC_PLUGIN_KEY"),
+	}
+
+	plugin.Serve(&plugin.ServeConfig{
+		HandshakeConfig: handshake,
+		Plugins: map[string]plugin.Plugin{
+			"email": &protobufs.NotifierPlugin{
+				Impl: &EmailPlugin{ConfigByName: make(map[string]PluginConfig)},
+			},
+		},
+		GRPCServer: plugin.DefaultGRPCServer,
+		Logger:     logger,
+	})
+}