# FBB::MailHeaders(3bobcat)

## SMTP Mail Headers
(libbobcat-dev_6.11.00)

## 2005-2025

## NAME

FBB::MailHeaders - Handles SMTP Mail Headers

## SYNOPSIS

#include <bobcat/mailheaders>
Linking option: -lbobcat

## DESCRIPTION

FBB::MailHeaders objects extract header lines from e-mail. Reading stops at (and including) the first blank line, which becomes the last element of the FBB::MailHeaders object, interpreted as a vector. The actual e-mail content is therefore left unread on the file containing the e-mail.

Each line stored in a MailHeaders object represents a complete header line. Headers continuing over multiple input lines are concatenated to a single line retrievable from MailHeaders objects, separated from each other by '\n' (newline) characters. The last line to join a multi-line header is not terminated by a newline character.

## NAMESPACE

FBB
All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace FBB.

## INHERITS FROM

-

## ENUMERATIONS

The following enumerations and enumeration values can be used with the class FBB::MailHeaders:

enum Mode
This enumeration defines two values:

- READ:
  When this value is specified at construction time, e-mail is immediately read by the constructor.
- DONT_READ:
  When this value is specified at construction time, e-mail is read using the read member (see below).

enum Match
This enumeration defines the following values:

- FULL:
  Used by setHeaderIterator (see below) to indicate that the headers must exactly match a specified header name.
- INITIAL:
  Used by setHeaderIterator (see below) to indicate that the initial part of the headers must match the specified header text.
- PARTIAL:
  Used by setHeaderIterator (see below) to indicate that the headers must contain the specified header text.
- CASE_FULL:
  Used by setHeaderIterator (see below) to indicate that the headers must exactly match a specified header name. The matching is performed case insensititvely.
- CASE_INITIAL:
  Used by setHeaderIterator (see below) to indicate that the initial part of the headers must match the specified header text. The matching is performed case insensititvely.
- CASE_PARTIAL:
  Used by setHeaderIterator (see below) to indicate that the headers must contain the specified header text. The matching is performed case insensititvely.

## NESTED TYPES

The class MailHeaders defines the following types:

- const_iterator:
  An input iterator returned by begin and end (see below)
- const_reverse_iterator:
  An reverse input iterator returned by the members rbegin and rend (see below)
- const_hdr_iterator:
  An input iterator returned by the members beginh and endh (see below)
- const_reverse_hdr_iterator:
  An reverse input iterator returned by the members rbeginh and rendh (see below)

Objects of these two iterator types point to header lines. Their dereferenced type is std::string.

## CONSTRUCTORS

- MailHeaders(std::istream &in, Mode mode = READ):
  This constructor defines the file containing the e-mail to be processed. The second parameter is by default MailHeaders::READ, causing the object to start reading the e-mail immediately. If set to MailHeaders::DONT_READ, the e-mail is not read. In that case the member read can be called to process the e-mail later.

The move constructor and move assignment operator is available.

## OVERLOADED OPERATORS

- std::string const &operator[](size_t idx) const:
  Returns the idx-th header line

## MEMBER FUNCTIONS

- const_iterator begin() const:
  Returns an iterator to the first line of the mail headers.

- const_hdr_iterator beginh() const:
  Returns the begin-iterator corresponding to the first header selected by the setHeaderIterator member.

- const_iterator end() const:
  Returns an iterator beyond the last line of the mail headers.

- const_hdr_iterator endh() const:
  Returns the end-iterator matching beginh. Note that the member function's name ends in h, to distinguish it from the vector<string>::end member.

- const_reverse_iterator rbegin() const:
  Returns an iterator to the last line of the mail headers.

- const_reverse_hdr_iterator rbeginh() const:
  Returns the reversed begin-iterator corresponding to the last header selected by the setHeaderIterator member.

- void read():
  Reads the mail-headers from the file passed to the FBB::MailHeaders object's constructor. An FBB::Exception object is thrown if the mailheaders were already read or if the file is incomplete (i.e., the (obligatory) blank line wasn't found).

- const_iterator rend() const:
  Returns an iterator before the first line of the mail headers.

- const_reverse_hdr_iterator rendh() const:
  Returns the reversed end-iterator matching rbeginh.

- void setHeaderIterator(char const *header, Match match = FULL):
  Sets the header-iterators to the specified header. The parameter match defines the match-type to use when selecting headers. The default FBB::MailHeaders::FULL, indicates that the text provided in header must match exactly an e-mail header.
  When matching headers the colon terminating the header is not considered and should therefore not be specified by setHeaderIterator.
  Alternative matching strategies are used when other values of the enumeration FBB::Match are specified.
  The member setHeaderIterator must have been called at least once or the members beginh and rendh will throw an FBB::Exception exception. An FBB::Exception exception is also thrown if setHeaderIterator is called when no mail headers are available.

- size_t size() const:
  Returns the number of header lines

## EXAMPLE

The following example shows the normal use of these members:

                    // create a MailHeader object
        MailHeaders mh(cin, MailHeaders::DONT_READ);

        try
        {           // read the headers
            mh.read();
        }
        catch (Exception &err)
        {
            cout << err.what() << endl;
        }

        cout << "There are " << mh.size() << " header lines\n";

                    // look for the Received: headers
        mh.setHeaderIterator("Received");

                    // show the Received headers
        copy(mh.beginh(), mh.endh(),
                ostream_iterator<std::string const>(cout, "\n"));

## FILES

bobcat/mailheaders - defines the class interface

## SEE ALSO

bobcat(7)

## BUGS

None Reported.

## BOBCAT PROJECT FILES

- https://fbb-git.gitlab.io/bobcat/: gitlab project page;

Debian Bobcat project files:

- libbobcat6: debian package containing the shared library, changelog and copyright note;
- libbobcat-dev: debian package containing the static library, headers, manual pages, and developer info;

## BOBCAT

Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.

## COPYRIGHT

This is free software, distributed under the terms of the GNU General Public License (GPL).

## AUTHOR

Frank B. Brokken (f.b.brokken@rug.nl).