dkim

type Middleware struct {
	// contains filtered or unexported fields
}

type SignerConfig struct {
	// AUID represents the DKIM Agent or User Identifier (AUID)
	// See: https://datatracker.ietf.org/doc/html/rfc6376#section-2.6
	//
	// A single identifier that refers to the agent or user on behalf of
	// whom the Signing Domain Identifier (SDID) has taken responsibility.
	// The AUID comprises a domain name and an optional <local-part>.  The
	// domain name is the same as that used for the SDID or is a subdomain
	// of it.  For DKIM processing, the domain name portion of the AUID has
	// only basic domain name semantics; any possible owner-specific
	// semantics are outside the scope of DKIM.
	//
	// AUID is optional and can be empty
	AUID string

	// CanonicalizationHeader defines the type of Canonicalization used for the mail.Msg header
	// Some mail systems modify email in transit, potentially invalidating a
	// signature.  For most Signers, mild modification of email is
	// immaterial to validation of the DKIM domain name's use.  For such
	// Signers, a canonicalization algorithm that survives modest in-transit
	// modification is preferred.
	//
	// If no canonicalization is defines, we default to CanonicalizationSimple
	//
	// See: https://datatracker.ietf.org/doc/html/rfc6376#section-3.4
	// See also: canonicalization.go#L7
	CanonicalizationHeader dkim.Canonicalization

	// CanonicalizationBody defines the type of Canonicalization used for the mail.Msg body
	// Some mail systems modify email in transit, potentially invalidating a
	// signature.  For most Signers, mild modification of email is
	// immaterial to validation of the DKIM domain name's use.  For such
	// Signers, a canonicalization algorithm that survives modest in-transit
	// modification is preferred.
	//
	// If no canonicalization is defines, we default to CanonicalizationSimple
	//
	// See: https://datatracker.ietf.org/doc/html/rfc6376#section-3.4
	// See also: canonicalization.go#L7
	CanonicalizationBody dkim.Canonicalization

	// Domain represents the DKIM Signing Domain Identifier (SDID)
	// See: https://datatracker.ietf.org/doc/html/rfc6376#section-2.5
	//
	// A single domain name that is the mandatory payload output of DKIM
	// and that refers to the identity claiming some responsibility for
	// the message by signing it.
	//
	// Domain MUST not be empty
	Domain string

	// Expiration is an optional expiration time of the signature.
	// See: https://www.rfc-editor.org/rfc/rfc6376.html#section-3.5
	//
	// Signatures MAY be considered invalid if the verification time at
	// the Verifier is past the expiration date. The verification
	// time should be the time that the message was first received at
	// the administrative domain of the Verifier if that time is
	// reliably available; otherwise, the current time should be
	// used.  The value of the "x=" tag MUST be greater than the value
	// of the "t=" tag if both are present.
	Expiration time.Time

	// HashAlgo represents the DKIM Hash Algorithms
	// See: https://datatracker.ietf.org/doc/html/rfc6376#section-7.7
	//
	// DKIM supports the following hashing algorithms
	//   - SHA256: This is the default and prefered algorithm
	//   - SHA1:   Due to comptibility reasons SHA1 is still supported but is
	//             not recommended to use it, since the SHA1 hashing algorithm has
	//             been proven to be broken
	HashAlgo crypto.Hash

	// HeaderFields is an optional list of header fields that should be used in
	// the signature. If the list is empty, all header fields will be used.
	//
	// If a list of headers is given via the HeaderFields slice, the FROM header
	// is always required.
	//
	// For a list of recommended signature headers, please refer to:
	// https://www.rfc-editor.org/rfc/rfc6376.html#section-5.4.1
	HeaderFields []string

	// Selector represents the DKIM domain selectors
	// See: https://datatracker.ietf.org/doc/html/rfc6376#section-3.1
	//
	// To support multiple concurrent public keys per signing domain, the
	// key namespace is subdivided using "selectors".  For example,
	// selectors might indicate the names of office locations (e.g.,
	// "sanfrancisco", "coolumbeach", and "reykjavik"), the signing date
	// (e.g., "january2005", "february2005", etc.), or even an individual
	// user.
	//
	// Selector MUST not be empty
	Selector string
}

type SignerOption func(config *SignerConfig) error