Struct MessageInstance 

pub struct MessageInstance {
    pub m: u32,
    pub hashes: Vec<MessageHash>,
    pub recipe: Option<Recipe>,
}

A parsed Message-Instance header field (§9).

Records the hashes of the message content at one revision and, for a revision made by a Reviser, the recipe that recreates the previous revision. Produced by MessageInstance::parse when a message is parsed, by MessageInstance::from_message and MessageInstance::from_recipe, and by the signers in Dkim2Signed::message_instance.

Fields

m: u32

m=: revision number, starting at 1 for the originator (§9.1).

hashes: Vec<MessageHash>

h=: header and body hashes of this revision, one entry per hash algorithm (§9.3).

recipe: Option<Recipe>

r=: recipe that recreates the previous revision from this one, or None if the tag is absent (§9.2).

Implementations

impl MessageInstance

pub fn write(&self, writer: &mut impl Writer)

Writes the complete Message-Instance header field on one line, terminated by CRLF. The recipe, if any, is written as base64-encoded JSON in the r= tag as it is, including one accepted leniently when parsed; the signers check Recipe::validate on recipes they generate before signing.

impl MessageInstance

pub fn parse(header: &[u8]) -> Result<MessageInstance>

Parses a single Message-Instance header field value (without the field name).

The value is a Tag=Value list (§8) with the same rules as Signature::parse. Hash names are case-sensitive; unsupported ones are kept as HashName::Unknown. The r= recipe is base64-decoded and parsed and validated as JSON (§5).

Errors

Returns Dkim2Error::InstanceSyntax for a malformed tag list or value or a repeated tag, Dkim2Error::InstanceTagMissing if m= or h= is missing, Dkim2Error::InstanceDuplicateHash if h= repeats a hash algorithm, and Dkim2Error::InvalidJson if the recipe is not valid JSON or does not follow the recipe schema.

impl MessageInstance

pub fn from_message( message: &AuthenticatedMessage<'_>, original: Option<&AuthenticatedMessage<'_>>, hashes: &[Dkim2Hash], ) -> Result<Option<Self>>

Builds the Message-Instance a signer adds to message, if one is needed (§12.1).

Without original, returns an instance with m=1 if message has no Message-Instance yet, and None otherwise. With original (the message before modification), computes Recipe::diff and returns a new instance carrying the recipe when the signed content changed, or when message has no instance yet. The instance number is one more than the highest existing m= and the hashes use hashes.

Errors

Returns Dkim2Error::HeaderNotRepresentable when Recipe::diff cannot record a changed header field.

pub fn from_recipe( message: &AuthenticatedMessage<'_>, recipe: Option<Recipe>, hashes: &[Dkim2Hash], ) -> Option<Self>

Builds a Message-Instance for message carrying recipe.

Returns None only when recipe is None and message already has a Message-Instance. The instance number is one more than the highest existing m= and the hashes of message use hashes.

Trait Implementations

impl Clone for MessageInstance

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MessageInstance

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for MessageInstance

fn default() -> Self

Returns the “default value” for a type.

impl Display for MessageInstance

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for MessageInstance

impl HeaderWriter for MessageInstance

fn write_header(&self, writer: &mut impl Writer)

Writes the complete header field, including the field name and the trailing CRLF, to writer.

fn to_header(&self) -> String

Returns the complete header field as a string, including the field name and the trailing CRLF. Invalid UTF-8 is replaced with U+FFFD.

impl PartialEq for MessageInstance

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for MessageInstance