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package textproto

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Published: May 28, 2020 | License: MIT | Module:


Package textproto implements low-level manipulation of MIME messages.



func WriteHeader

func WriteHeader(w io.Writer, h Header) error

WriteHeader writes a MIME header to w.

type Header struct {
	// contains filtered or unexported fields

A Header represents the key-value pairs in a message header.

The header representation is idempotent: if the header can be read and written, the result will be exactly the same as the original (including whitespace and header field ordering). This is required for e.g. DKIM.

Mutating the header is restricted: the only two allowed operations are inserting a new header field at the top and deleting a header field. This is again necessary for DKIM.



var h textproto.Header
h.Add("From", "<>")
h.Add("To", "<>")
h.Set("Subject", "Tonight's dinner")

fmt.Println("From: ", h.Get("From"))
fmt.Println("Has Received: ", h.Has("Received"))

fmt.Println("Header fields:")
fields := h.Fields()
for fields.Next() {
	fmt.Println("  ", fields.Key())

func ReadHeader

func ReadHeader(r *bufio.Reader) (Header, error)

ReadHeader reads a MIME header from r. The header is a sequence of possibly continued Key: Value lines ending in a blank line.

func (*Header) Add

func (h *Header) Add(k, v string)

Add adds the key, value pair to the header. It prepends to any existing fields associated with key.

Key and value should obey character requirements of RFC 6532. If you need to format/fold lines manually, use AddRaw

func (*Header) AddRaw

func (h *Header) AddRaw(kv []byte)

AddRaw adds the raw key, value pair to the header.

The supplied byte slice should be a complete field in the "Key: Value" form including trailing CRLF. If there is no comma in the input - AddRaw panics. No changes are made to kv contents and it will be copied into WriteHeader output as is.

kv is directly added to the underlying structure and therefore should not be modified after the AddRaw call.

func (*Header) Copy

func (h *Header) Copy() Header

Copy creates an independent copy of the header.

func (*Header) Del

func (h *Header) Del(k string)

Del deletes the values associated with key.

func (*Header) Fields

func (h *Header) Fields() HeaderFields

Fields iterates over all the header fields.

The header may not be mutated while iterating, except using HeaderFields.Del.

func (*Header) FieldsByKey

func (h *Header) FieldsByKey(k string) HeaderFields

FieldsByKey iterates over all fields having the specified key.

The header may not be mutated while iterating, except using HeaderFields.Del.

func (*Header) Get

func (h *Header) Get(k string) string

Get gets the first value associated with the given key. If there are no values associated with the key, Get returns "".

func (*Header) Has

func (h *Header) Has(k string) bool

Has checks whether the header has a field with the specified key.

func (*Header) Len

func (h *Header) Len() int

Len returns the number of fields in the header.

func (*Header) Raw

func (h *Header) Raw(k string) ([]byte, error)

Raw gets the first raw header field associated with the given key.

The returned bytes contain a complete field in the "Key: value" form, including trailing CRLF.

The returned slice should not be modified and becomes invalid when the header is updated.

Error is returned if header contains incorrect characters (RFC 6532)

func (*Header) Set

func (h *Header) Set(k, v string)

Set sets the header fields associated with key to the single field value. It replaces any existing values associated with key.

type HeaderFields

type HeaderFields interface {
	// Next advances to the next header field. It returns true on success, or
	// false if there is no next field.
	Next() (more bool)
	// Key returns the key of the current field.
	Key() string
	// Value returns the value of the current field.
	Value() string
	// Raw returns the raw current header field. See Header.Raw.
	Raw() ([]byte, error)
	// Del deletes the current field.
	// Len returns the amount of header fields in the subset of header iterated
	// by this HeaderFields instance.
	// For Fields(), it will return the amount of fields in the whole header section.
	// For FieldsByKey(), it will return the amount of fields with certain key.
	Len() int

HeaderFields iterates over header fields. Its cursor starts before the first field of the header. Use Next to advance from field to field.

type MultipartReader

type MultipartReader struct {
	// contains filtered or unexported fields

MultipartReader is an iterator over parts in a MIME multipart body. MultipartReader's underlying parser consumes its input as needed. Seeking isn't supported.

func NewMultipartReader

func NewMultipartReader(r io.Reader, boundary string) *MultipartReader

NewMultipartReader creates a new multipart reader reading from r using the given MIME boundary.

The boundary is usually obtained from the "boundary" parameter of the message's "Content-Type" header. Use mime.ParseMediaType to parse such headers.

func (*MultipartReader) NextPart

func (r *MultipartReader) NextPart() (*Part, error)

NextPart returns the next part in the multipart or an error. When there are no more parts, the error io.EOF is returned.

type MultipartWriter

type MultipartWriter struct {
	// contains filtered or unexported fields

A MultipartWriter generates multipart messages.

func NewMultipartWriter

func NewMultipartWriter(w io.Writer) *MultipartWriter

NewMultipartWriter returns a new multipart Writer with a random boundary, writing to w.

func (*MultipartWriter) Boundary

func (w *MultipartWriter) Boundary() string

Boundary returns the Writer's boundary.

func (*MultipartWriter) Close

func (w *MultipartWriter) Close() error

Close finishes the multipart message and writes the trailing boundary end line to the output.

func (*MultipartWriter) CreatePart

func (w *MultipartWriter) CreatePart(header Header) (io.Writer, error)

CreatePart creates a new multipart section with the provided header. The body of the part should be written to the returned Writer. After calling CreatePart, any previous part may no longer be written to.

func (*MultipartWriter) SetBoundary

func (w *MultipartWriter) SetBoundary(boundary string) error

SetBoundary overrides the Writer's default randomly-generated boundary separator with an explicit value.

SetBoundary must be called before any parts are created, may only contain certain ASCII characters, and must be non-empty and at most 70 bytes long.

type Part

type Part struct {
	Header Header
	// contains filtered or unexported fields

A Part represents a single part in a multipart body.

func (*Part) Close

func (p *Part) Close() error

func (*Part) Read

func (p *Part) Read(d []byte) (n int, err error)

Read reads the body of a part, after its headers and before the next part (if any) begins.

type TooBigError

type TooBigError struct {
	// contains filtered or unexported fields

TooBigError is returned by ReadHeader if one of header components are larger than allowed.

func (TooBigError) Error

func (err TooBigError) Error() string
Documentation was rendered with GOOS=linux and GOARCH=amd64.

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