class Poco::Net::MessageHeader

Overview

A collection of name-value pairs that are used in various internet protocols like HTTP and SMTP. More…

#include <MessageHeader.h>

class MessageHeader: public Poco::Net::NameValueCollection
{
public:
    // construction

    MessageHeader();
    MessageHeader(const MessageHeader& messageHeader);

    // methods

    MessageHeader&
    operator=(const MessageHeader& messageHeader);

    virtual
    void
    write(std::ostream& ostr) const;

    virtual
    void
    read(std::istream& istr);

    int
    getFieldLimit() const;

    void
    setFieldLimit(int limit);

    bool
    hasToken(
        const std::string& fieldName,
        const std::string& token
        ) const;

    static
    void
    splitElements(
        const std::string& s,
        std::vector<std::string>& elements,
        bool ignoreEmpty = true
        );

    static
    void
    splitParameters(
        const std::string& s,
        std::string& value,
        NameValueCollection& parameters
        );

    static
    void
    splitParameters(
        const std::string::const_iterator& begin,
        const std::string::const_iterator& end,
        NameValueCollection& parameters
        );

    static
    void
    quote(
        const std::string& value,
        std::string& result,
        bool allowSpace = false
        );
};

// direct descendants

class HTTPMessage;
class MailMessage;

Inherited Members

public:
    // typedefs

    typedef Poco::ListMap<std::string, std::string> HeaderMap;
    typedef HeaderMap::Iterator Iterator;
    typedef HeaderMap::ConstIterator ConstIterator;

    // methods

    NameValueCollection&
    operator=(const NameValueCollection& nvc);

    void
    swap(NameValueCollection& nvc);

    const std::string&
    operator[](const std::string& name) const;

    void
    set(
        const std::string& name,
        const std::string& value
        );

    void
    add(
        const std::string& name,
        const std::string& value
        );

    const std::string&
    get(const std::string& name) const;

    const std::string&
    get(
        const std::string& name,
        const std::string& defaultValue
        ) const;

    bool
    has(const std::string& name) const;

    ConstIterator
    find(const std::string& name) const;

    ConstIterator
    begin() const;

    ConstIterator
    end() const;

    bool
    empty() const;

    std::size_t
    size() const;

    void
    erase(const std::string& name);

    void
    clear();

Detailed Documentation

A collection of name-value pairs that are used in various internet protocols like HTTP and SMTP.

The name is case-insensitive.

There can be more than one name-value pair with the same name.

MessageHeader supports writing and reading the header data in RFC 2822 format.

The maximum number of fields can be restricted by calling setFieldLimit(). This is useful to defend against certain kinds of denial-of-service attacks. The limit is only enforced when parsing header fields from a stream, not when programmatically adding them. The default limit is 100.

Construction

MessageHeader()

Creates the MessageHeader.

MessageHeader(const MessageHeader& messageHeader)

Creates the MessageHeader by copying another one.

Methods

MessageHeader&
operator=(const MessageHeader& messageHeader)

Assigns the content of another MessageHeader.

virtual
void
write(std::ostream& ostr) const

Writes the message header to the given output stream.

The format is one name-value pair per line, with name and value separated by a colon and lines delimited by a carriage return and a linefeed character. See RFC 2822 for details.

virtual
void
read(std::istream& istr)

Reads the message header from the given input stream.

See write() for the expected format. Also supported is folding of field content, according to section 2.2.3 of RFC 2822.

Reading stops at the first empty line (a line only containing

or

), as well as at the end of the stream.

Some basic sanity checking of the input stream is performed.

Throws a MessageException if the input stream is malformed.

int
getFieldLimit() const

Returns the maximum number of header fields allowed.

See setFieldLimit() for more information.

void
setFieldLimit(int limit)

Sets the maximum number of header fields allowed.

This limit is used to defend certain kinds of denial-of-service attacks. Specify 0 for unlimited (not recommended).

The default limit is 100.

bool
hasToken(
    const std::string& fieldName,
    const std::string& token
    ) const

Returns true iff the field with the given fieldName contains the given token.

Tokens in a header field are expected to be comma-separated and are case insensitive.

static
void
splitElements(
    const std::string& s,
    std::vector<std::string>& elements,
    bool ignoreEmpty = true
    )

Splits the given string into separate elements.

Elements are expected to be separated by commas.

For example, the string

text/plain; q=0.5, text/html, text/x-dvi; q=0.8

is split into the elements

text/plain; q=0.5
text/html
text/x-dvi; q=0.8

Commas enclosed in double quotes do not split elements.

If ignoreEmpty is true, empty elements are not returned.

static
void
splitParameters(
    const std::string& s,
    std::string& value,
    NameValueCollection& parameters
    )

Splits the given string into a value and a collection of parameters.

Parameters are expected to be separated by semicolons.

Enclosing quotes of parameter values are removed.

For example, the string

multipart/mixed; boundary="MIME_boundary_01234567"

is split into the value

multipart/mixed

and the parameter

boundary -> MIME_boundary_01234567

static
void
splitParameters(
    const std::string::const_iterator& begin,
    const std::string::const_iterator& end,
    NameValueCollection& parameters
    )

Splits the given string into a collection of parameters.

Parameters are expected to be separated by semicolons.

Enclosing quotes of parameter values are removed.

static
void
quote(
    const std::string& value,
    std::string& result,
    bool allowSpace = false
    )

Checks if the value must be quoted.

If so, the value is appended to result, enclosed in double-quotes. Otherwise, the value is appended to result as-is.