milter

README

milter

-- import "milter"

The milter package is a framework for writing milters (mail filters) for Sendmail and Postfix.

To implement a milter, make a type that implements the Milter interface, listen on a Unix or TCP socket, and call Serve with that socket and a factory function that returns instances of your Milter type.

Documentation

Overview

The milter package is a framework for writing milters (mail filters) for Sendmail and Postfix.

To implement a milter, make a type that implements the Milter interface, listen on a Unix or TCP socket, and call Serve with that socket and a factory function that returns instances of your Milter type.

Index

• Constants
• func Serve(l net.Listener, newMilter func() Milter) error
• type CustomResponse
  • func (r CustomResponse) Response() (code byte, data []byte)
• type Milter
• type Modifier
• type Response

Constants

const (
	// Accept indicates that the message should be accepted and delivered, with
	// no further processing.
	Accept = simpleResponse('a')

	// Continue indicates that processing of the message should continue. Milter
	// methods should have Continue as their default return value.
	Continue = simpleResponse('c')

	// Discard indicates that the message should be discarded silently (without
	// giving an error to the sender).
	Discard = simpleResponse('d')

	// Reject rejects the message or recipient with a permanent error (5xx).
	Reject = simpleResponse('r')

	// TempFail rejects the message or recipient with a temporary error (4xx).
	TempFail = simpleResponse('t')
)

Functions

func Serve

func Serve(l net.Listener, newMilter func() Milter) error

Serve accepts connections received on l, and processes them with milters returned by newMilter.

Types

type CustomResponse

type CustomResponse struct {
	Code    int
	Message string
}

A CustomResponse responds with a custom status code and message.

func (CustomResponse) Response

func (r CustomResponse) Response() (code byte, data []byte)

type Milter

type Milter interface {
	// Connect is called when a new SMTP connection is received. The values for
	// network and address are in the same format that would be passed to net.Dial.
	Connect(hostname string, network string, address string, macros map[string]string) Response

	// Helo is called when the client sends its HELO or EHLO message.
	Helo(name string, macros map[string]string) Response

	// From is called when the client sends its MAIL FROM message. The sender's
	// address is passed without <> brackets.
	From(sender string, macros map[string]string) Response

	// To is called when the client sends a RCPT TO message. The recipient's
	// address is passed without <> brackets. If it returns a rejection Response,
	// only the one recipient is rejected.
	To(recipient string, macros map[string]string) Response

	// Headers is called when the message headers have been received.
	Headers(h textproto.MIMEHeader) Response

	// Body is called when the message body has been received. It gives an
	// opportunity for the milter to modify the message before it is delivered.
	Body(body []byte, m Modifier) Response
}

A Milter examines email messages and decides what to do with them. Users of this package implement the Milter interface, and the methods are called in order as the conversation with the mail transfer agent proceeds. A single Milter may be used to process multiple messages; in that case the flow will jump back to an earlier point in the sequence of methods.

If a method pertains to a stage in the mail workflow that the milter is not interested in, it should just return Continue.

The final argument to most of the methods is macros, a map of extra, MTA- specific information. (If the MTA sent the macro names enclosed in curly braces, they have been removed.)

type Modifier

type Modifier interface {
	// AddRecipient adds a recipient to the message.
	AddRecipient(r string)

	// DeleteRecipient removes a recipient from the message.
	DeleteRecipient(r string)

	// ReplaceBody replaces the message body.
	ReplaceBody(newBody []byte)

	// AddHeader adds a header.
	AddHeader(name, value string)

	// ChangeHeader replaces an existing header. Since there can be multiple
	// headers with the same name, index specifies which one to change;
	// the first header with that name is numbered 1 (not 0). To delete a
	// header, replace it with the empty string.
	ChangeHeader(name string, index int, value string)
}

A Modifier provides methods for modifying the current message.

type Response

type Response interface {
	Response() (code byte, data []byte)
}

A Response determines what will be done with a message or recipient.