class Mail::Header
Provides access to a header object.
Per RFC2822¶ ↑
2.2. Header Fields Header fields are lines composed of a field name, followed by a colon (":"), followed by a field body, and terminated by CRLF. A field name MUST be composed of printable US-ASCII characters (i.e., characters that have values between 33 and 126, inclusive), except colon. A field body may be composed of any US-ASCII characters, except for CR and LF. However, a field body may contain CRLF when used in header "folding" and "unfolding" as described in section 2.2.3. All field bodies MUST conform to the syntax described in sections 3 and 4 of this standard.
Attributes
Public Class Methods
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# File lib/mail/header.rb, line 31 def self.maximum_amount @@maximum_amount end
Large amount of headers in Email might create extra high CPU load Use this parameter to limit number of headers that will be parsed by mail library. Default: 1000
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# File lib/mail/header.rb, line 35 def self.maximum_amount=(value) @@maximum_amount = value end
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# File lib/mail/header.rb, line 53 def initialize(header_text = nil, charset = nil) @charset = charset @raw_source = ::Mail::Utilities.to_crlf(header_text).lstrip split_header if header_text end
Creates a new header object.
Accepts raw text or nothing. If given raw text will attempt to parse it and split it into the various fields, instantiating each field as it goes.
If it finds a field that should be a structured field (such as content type), but it fails to parse it, it will simply make it an unstructured field and leave it alone. This will mean that the data is preserved but no automatic processing of that field will happen. If you find one of these cases, please make a patch and send it in, or at the least, send me the example so we can fix it.
Public Instance Methods
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# File lib/mail/header.rb, line 130 def [](name) fields.get_field(Utilities.dasherize(name)) end
3.6. Field definitions The following table indicates limits on the number of times each field may occur in a message header as well as any special limitations on the use of those fields. An asterisk next to a value in the minimum or maximum column indicates that a special restriction appears in the Notes column. <snip table from 3.6>
As per RFC, many fields can appear more than once, we will return a string of the value if there is only one header, or if there is more than one matching header, will return an array of values in order that they appear in the header ordered from top to bottom.
Example:
h = Header.new h.fields = ['To: mikel@me.com', 'X-Mail-SPAM: 15', 'X-Mail-SPAM: 20'] h['To'] #=> 'mikel@me.com' h['X-Mail-SPAM'] #=> ['15', '20']
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# File lib/mail/header.rb, line 147 def []=(name, value) name = name.to_s if name.include?(Constants::COLON) raise ArgumentError, "Header names may not contain a colon: #{name.inspect}" end name = Utilities.dasherize(name) # Assign nil to delete the field if value.nil? fields.delete_field name else fields.add_field Field.new(name.to_s, value, charset) # Update charset if specified in Content-Type if name == 'content-type' params = self[:content_type].parameters rescue nil @charset = params[:charset] if params && params[:charset] end end end
Sets the FIRST matching field in the header to passed value, or deletes the FIRST field matched from the header if passed nil
Example:
h = Header.new h.fields = ['To: mikel@me.com', 'X-Mail-SPAM: 15', 'X-Mail-SPAM: 20'] h['To'] = 'bob@you.com' h['To'] #=> 'bob@you.com' h['X-Mail-SPAM'] = '10000' h['X-Mail-SPAM'] # => ['15', '20', '10000'] h['X-Mail-SPAM'] = nil h['X-Mail-SPAM'] # => nil
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# File lib/mail/header.rb, line 169 def charset=(val) params = self[:content_type].parameters rescue nil if params if val params[:charset] = val else params.delete(:charset) end end @charset = val end
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# File lib/mail/header.rb, line 195 def decoded raise NoMethodError, 'Can not decode an entire header as there could be character set conflicts. Try calling #decoded on the various fields.' end
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# File lib/mail/header.rb, line 182 def encoded buffer = String.new buffer.force_encoding('us-ascii') if buffer.respond_to?(:force_encoding) fields.each do |field| buffer << field.encoded end buffer end
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# File lib/mail/header.rb, line 105 def errors @fields.map(&:errors).flatten(1) end
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# File lib/mail/header.rb, line 67 def fields @fields ||= FieldList.new end
Returns an array of all the fields in the header in order that they were read in.
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# File lib/mail/header.rb, line 90 def fields=(unfolded_fields) @fields = Mail::FieldList.new if unfolded_fields.size > self.class.maximum_amount Kernel.warn "WARNING: More than #{self.class.maximum_amount} header fields; only using the first #{self.class.maximum_amount} and ignoring the rest" unfolded_fields = unfolded_fields.slice(0...self.class.maximum_amount) end unfolded_fields.each do |field| if field = Field.parse(field, charset) @fields.add_field field end end end
3.6. Field definitions It is important to note that the header fields are not guaranteed to be in a particular order. They may appear in any order, and they have been known to be reordered occasionally when transported over the Internet. However, for the purposes of this standard, header fields SHOULD NOT be reordered when a message is transported or transformed. More importantly, the trace header fields and resent header fields MUST NOT be reordered, and SHOULD be kept in blocks prepended to the message. See sections 3.6.6 and 3.6.7 for more information.
Populates the fields container with Field
objects in the order it receives them in.
Acceps an array of field string values, for example:
h = Header.new h.fields = ['From: mikel@me.com', 'To: bob@you.com']
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# File lib/mail/header.rb, line 209 def has_content_id? fields.has_field? 'Content-ID' end
Returns true if the header has a Content-ID defined (empty or not)
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# File lib/mail/header.rb, line 214 def has_date? fields.has_field? 'Date' end
Returns true if the header has a Date defined (empty or not)
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# File lib/mail/header.rb, line 204 def has_message_id? fields.has_field? 'Message-ID' end
Returns true if the header has a Message-ID defined (empty or not)
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# File lib/mail/header.rb, line 219 def has_mime_version? fields.has_field? 'Mime-Version' end
Returns true if the header has a MIME version defined (empty or not)
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# File lib/mail/header.rb, line 59 def initialize_copy(original) super @fields = @fields.dup @fields.map!(&:dup) end
Private Instance Methods
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# File lib/mail/header.rb, line 233 def each(&block) fields.each(&block) end
Enumerable support. Yield each field in order.
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# File lib/mail/header.rb, line 227 def split_header self.fields = @raw_source.split(Constants::HEADER_SPLIT) end
Splits an unfolded and line break cleaned header into individual field strings.