Net::Inspect::L7::HTTP(3)

NAME
Net::Inspect::L7::HTTP - guesses and handles HTTP traffic

SYNOPSIS
 my $req = Net::Inspect::L7::HTTP::Request::Simple->new(..);
 my $http = Net::Inspect::L7::HTTP->new($req);
 my $guess = Net::Inspect::L5::GuessProtocol->new;
 $guess->attach($http);
 ...

DESCRIPTION
This class extracts HTTP requests from TCP connections. It provides all hooks required for "Net::Inspect::L4::TCP" and is usually used together with it. It provides the "guess_protocol" hook so it can be used with "Net::Inspect::L5::GuessProtocol".

Attached flow is usually a "Net::Inspect::L7::HTTP::Request::*" object.

Hooks provided:

guess_protocol($guess,$dir,$data,$eof,$time,$meta)
new_connection($meta)
    This returns an object for the connection.

$connection->in($dir,$data,$eof,$time)
    Processes new data and returns number of bytes processed. Any data not processed must be sent again with the next call.

    $data are the data as string. In some cases $data can be "[ 'gap' => $len ]", e.g. only the information, that there would be $len bytes of data w/o submitting the data. These should only be submitted in request and response bodies and only if the attached layer can handle these gaps in the "in_request_body" and "in_response_body" methods.

    Gaps on other places are not allowed, because all other data are needed for interpreting the placement of request, response and data inside the connection.

$connection->fatal($reason,$dir,$time)

Hooks called:

new_request(\%meta,$conn)
    This should return an request object. The reference to the connection object is given in case the request object likes to call "fatal" to end the connection.

    The function should not get hold of $conn, e.g. only store a weak reference, otherwise memory might leak.

$request->in_request_header($header,$time,\%hdr_meta)
    Called when the full request header is read. $header is the string of the header.

    %hdr_meta contains information extracted from the header:

    method - method of request
    url - url, as given in request
    version - version of HTTP spoken in request
    fields - (key => \@values) hash of header fields
    junk - invalid data found in header fields part
    content_length - length of request body
    chunked - true if body uses transfer encoding chunked
$request->in_response_header($header,$time,\%hdr_meta)
    Called when the full response header is read. $header is the string of the header.

    %hdr_meta contains information extracted from the header:

    version - version of HTTP spoken in response
    code - status code from response
    reason - reason given for response code
    fields - (key => \@values) hash of header fields
    junk - invalid data found in header fields part
    content_length - length of request body if known, else undef
    chunked - true if body uses transfer encoding chunked
$request->in_request_body($data,$eobody,$time)
    Called for a chunk of data of the request body. $eobody is true if this is the last chunk of the request body. If the request body is empty the method will be called once with ''. If no body exists because of CONNECT or HTTP Upgrade "in_data" will be called, not "in_request_body".

    $data can be "[ 'gap' => $len ]" if the input to this layer were gaps.

$request->in_response_body($data,$eobody,$time)
    Called for a chunk of data of the response body. $eof is true if this is the last chunk of the connection. $eobody is true if this is the last chunk of the response body. If the response body is empty the method will be called once with ''. If no body exists because of CONNECT or HTTP Upgrade "in_data" will be called, not "in_response_body".

    $data can be "[ 'gap' => $len ]" if the input to this layer were gaps.

$request->in_chunk_header($dir,$header,$time)
    will be called with the chunk header for chunked encoding. Usually one is not interested in the chunk framing, only in the content so that this method will be empty. Will be called before the chunk data.

$request->in_chunk_trailer($dir,$trailer,$time)
    will be called with the chunk trailer for chunked encoding. Usually one is not interested in the chunk framing, only in the content so that this method will be empty. Will be called after in_response_body/in_request_body got called with eof true.

$request->in_data($dir,$data,$eof,$time)
    Will be called for any data after successful CONNECT or Upgrade, Websockets... $dir is 0 for data from client, 1 for data from server.

$request->in_junk($dir,$data,$eof,$time)
    Will be called for legally ignored junk (empty lines) in front of request or response body. $dir is 0 for data from client, 1 for data from server.

$request->fatal($reason,$dir,$time)
    will be called on fatal errors, mostly protocol iregularities.

Methods suitable for overwriting:

new_request(\%meta)
    default implementation will just call new_request from the attached flow

Helpful methods

$connection->dump_state
    collects the state of the open connections. If defined wantarray it will return a message, otherwise output it via xdebug

$connection->offset(@dir)
    returns the current offset(s) in the data stream, that is the position behind the within the in_* methods forwarded data.

$connection->gap_offset(@dir)
    If the next bytes of the input stream are not needed to interpret the HTTP protocol (i.e. plain body data) this gives the offsets up to which data are "gapable". If no gaps are possible at the current state 0 will be returned. If everything can be gaps (usually because end of body is caused by end of connection) "-1" will be returned.

$connection->gap_diff(@dir)
    This is similar to "gap_offset" but will return the difference from the current position, i.e. how large the next gap can be. "-1" again means an unlimited gap.

$connection->open_requests(@index)
    in array context returns the objects for the open requests, in scalar context the number of open requests. If index is given only the specified objects will be returned, e.g. index -1 is the object currently receiving response data while index 0 specifies the object currently receiving request data (both are the same unless pipelining is used)

exportable utility functions and constants

METHODS_WITHOUT_RQBODY
    This constant is an array reference of all request methods which will not have a request body, i.e. which have an implicit and non-changeble content-length of 0.

METHODS_WITH_RQBODY
    This constant is an array reference of all request methods which must have a specified request body, even if the content-lenth is explicitly set to 0.

    Methods which are not in METHODS_WITH_RQBODY or METHODS_WITHOUT_RQBODY might have a request body, that is if no content-length is explicitly given (or chunked transfer encoding is used) it is assumed that they don't have a body.

METHODS_WITHOUT_RPBODY
    This constant is an array reference of all request methods which don't require a response body, i.e. which have an implicit and non-changeble content-length of 0.

CODE_WITHOUT_RPBODY
    This constant is an array reference of all response codes which will not have a response body, i.e. which have an implicit and non-changeble content-length of 0.

parse_hdr_fields($header,\%fields) -> $bad_header
    This function parses the given message header (without request or status line!) and extracts the "key:value" pairs into %fields. Each key in %fields is the lower-case representation of the key from the HTTP message and the value in %fields is a list with all values, i.e. a list with a single element if the specific key was only used once the header, but with multiple elements if the key was used multiple times. Any continuation lines will be transformed into a single line.

    It will return any remaining data in $header which could not be interpreted as proper "key:value" pairs. If the message contains no errors it will thus return ''.

LIMITS
"100 Continue", "101 Upgrade" are not yet implemented.