# Module Nethttpd_services

    module Nethttpd_services: sig .. end

# Service Providers for HTTP daemon

This module defines the basic service providers that handle requests and generate responses. The service providers can be used with both the reactive and the event-based daemon encapsulations.

`type ``host = {`

`` | `server_pref_name : `string option`;` | `(*` | The preferred name of the host. This can be a DNS name or an IP address. | `*)`
`` | `server_pref_port : `int option`;` | `(*` | The preferred port of the host | `*)`
`` | `server_names : `(string * int) list`;` | `(*` | Names and ports that match this host definition, for name-based virtual hosting. The name `"*"` matches any name, and the port 0 matches any port. | `*)`
`` | `server_addresses : `(Unix.inet_addr * int) list`;` | `(*` | IP addresses and ports that also match this host definition, for IP-based virtual hosting. The address `Unix.inet_addr_any` matches any address, and the port 0 matches any port. | `*)`

}
For name- and IP-based virtual hosting this record describes the individual host. An incoming request matches this host if:

- The `Host` header is mentioned in `server_names`, or if
- The request has been accepted on the port contained in `server_addresses`

If `server_pref_name` is set, the name of the host is set to this string for further processing (esp. `cgi_server_name`). If not set, the name of the host is set to the name corresponding to the matching entry of `server_names` or `server_addresses`, or if this does not succeed, to the real IP address.

If `server_pref_port` is set, the port of the host is set to this string for further processing (esp. `cgi_server_port`). If not set, the port of the host is set to the port corresponding to the matching entry of `server_names` or `server_addresses`, or if this does not succeed, to the real port number.

    type 'a host_distributor = (host * 'a Nethttpd_types.http_service) list

Describes virtual hosting by pairs `(host,service)`: If `host` matches the incoming request, the corresponding `service` is performed to generate the response.

    val host_distributor : 'a host_distributor ->
           [> `Host_distributor of 'a host_distributor ]
           Nethttpd_types.http_service

Configures virtual hosting

    val default_host : ?pref_name:string -> ?pref_port:int -> unit -> host

Creates a `host` record that matches any request. `pref_name` and `pref_port` can be used to specify preferred names.

    val options_service : unit -> [> `Options_service ] Nethttpd_types.http_service

This service responds to "OPTIONS *" requests, and nothing else

    type 'a uri_distributor = (string * 'a Nethttpd_types.http_service) list

Describes that services are bound to URI prefixes. The strings are URI paths (without URI escaping). For an incoming request URI, the longest matching prefix is selected, and the corresponding service is carried out.

If the URI path in the list ends with a slash, it can only be selected if the incoming request URI also includes the slash.

If the URI path in the list does not end with a slash, it can only be selected if the incoming request URI is exactly identical, or continues the path with a slash.

    val uri_distributor : 'a uri_distributor ->
           [> `Uri_distributor of 'a uri_distributor ]
           Nethttpd_types.http_service

Configures URI distribution. The incoming request URI is normalized before being matched, and the request is rewritten to the normalized URI.

Normalization includes:

- Removal of `.` path components
- Resolution of `..` path components

If the path starts with `..` after normalization, the request is rejected.

    type 'a linear_distributor = ((Nethttpd_types.extended_environment -> bool) *
            'a Nethttpd_types.http_service)
           list

Services are selected by calling the selector function. The first service for which the function returns `true` is selected.

    val linear_distributor : 'a linear_distributor ->
           [> `Linear_distributor of 'a linear_distributor ]
           Nethttpd_types.http_service

Configures linear distribution

    type method_filter = [ `Limit of string list | `Limit_except of string list ]

The request is only accepted if listed (for ``Limit`), or if not listed (for ``Limit_except`).

    type 'a method_distributor = (method_filter * 'a Nethttpd_types.http_service) list

The first service is selected for which the method filter accepts the request

    val method_distributor : 'a method_distributor ->
           [> `Method_distributor of 'a method_distributor ]
           Nethttpd_types.http_service

Configures method distribution

    type file_option = [ `Enable_cooked_compression
           | `Enable_gzip
           | `Enable_index_file of string list
           | `Enable_listings of
               Nethttpd_types.extended_environment ->
               Netcgi.cgi_activation -> file_service -> unit
           | `Override_compression_suffixes of (string * string) list ]

Add-on features for file services:

- ``Enable_gzip`: Deprecated. Same as ``Enable_cooked_compression`.
- ``Enable_cooked_compression`: Modifies the way compressed files are handled. Normally it is required that one accesses the compressed file (with suffix such as "gz") directly to get it in compressed form. If this option is enabled, though, the server also compresses the base file (without suffix such as "gz"), but only if the base file is accompanied by a compressed version (with suffix). E.g. if there is "foo" and "foo.gz", this enables that the accesses to "foo" can make use of compression.
- ``Enable_index_file`: If enabled, accesses to directories are redirected to index files. The possible file names are given in the string list. E.g. ``Enable_index_file ["index.html"; "index.htm"]`. It is redirected to these files, so these can be handled by different services if neccessary.
- ``Enable_listings`: If enabled, directory listings are generated by calling the argument function. The `PATH_TRANSLATED` property of the environment contains the absolute name of the directory to list. The `PATH_INFO` property is the corresponding URI path. `SCRIPT_NAME` is meaningless.
- ``Override_compression_suffixes l`: Tags the file suffixes in `l` as compression schemes. A pair `(suffix,ce)` sets that the `suffix` means the content encoding `ce`. Knowing this is important for determining the media type of the file.

`type ``file_service = {`

`` | `file_docroot : `string`;` | `(*` | The document root for this file service | `*)`
`` | `file_uri : `string`;` | `(*` | The URI prefix corresponding to the document root. Escapes are not allowed | `*)`
`` | `file_suffix_types : `(string * string) list`;` | `(*` | Maps the file suffixes (after the dot) to media types | `*)`
`` | `file_default_type : `string`;` | `(*` | The media type to use if suffix mapping fails | `*)`
`` | `file_options : `file_option list`;` | `(*` | Further options for files | `*)`

}
Describes a file service

    val file_service : file_service ->
           [> `File_service of file_service ]
           Nethttpd_types.http_service

Configures a file service

    val file_translator : file_service -> string -> string

Translates an URI path to a file name. Raises `Not_found` if not possible. It is not checked whether the resulting file exists.

This function removes a trailing slash of the translated path, if any, and if resulting from appending the path info component. Trailing slashes must not be used to deduce that directories are accessed.

    val simple_listing : ?hide:string list ->
           Nethttpd_types.extended_environment ->
           Netcgi.cgi_activation -> file_service -> unit

Simple listing generator for ``Enable_listings`

`hide`: An optional list of Str regular expressions. File names matching one of the regexps are hidden in the listing. Defaults to hiding files starting with a dot, and files ending in a tilde character. (Changed in Ocamlnet-3.3: `hide` uses now Str regexps, and no longer PCRE regexps.)

`type ``std_activation_options = {`

`` | `stdactv_processing : `Netcgi.arg_store option`;`
`` | `stdactv_operating_type : `Netcgi.output_type option`;`

}
These are options for ``Std_activation`. For explanations, see the `Netcgi` module.

    type std_activation = [ `Std_activation of std_activation_options
           | `Std_activation_buffered
           | `Std_activation_tempfile
           | `Std_activation_unbuffered ]

The way the `Netcgi_types.cgi_activation` object is created. For typical usage, just take:

- ``Std_activation_unbuffered`: Creates a `Netcgi.std_activation` without output buffer (type ``Direct ""`) and memory-based argument processing
- ``Std_activation_buffered`: Creates a `Netcgi.std_activation` with a transactions buffer in memory, and memory-based argument processing
- ``Std_activation_tempfile`: Creates a `Netcgi.std_activation` with a file as transactions buffer, and memory-based argument processing

The following option is provided for detailed control:

- ``Std_activation opt`: Creates a `Netcgi.std_activation` with the given options

`type `#Netcgi.cgi_activation` dynamic_service = {`

`` | `dyn_handler : `Nethttpd_types.extended_environment -> (#Netcgi.cgi_activation as 'a) -> unit`;` | `(*` | A dynamic service is carried out by calling this function with the environment and the CGI activation. The function can use all CGI features, including setting the `Location` handler to redirect responses. | `*)`
`` | `dyn_activation : `Nethttpd_types.extended_environment -> 'a`;` | `(*` | The way the `Netcgi_types.cgi_activation` is created. Look below for `std_activation`. | `*)`
`` | `dyn_uri : `string option`;` | `(*` | The URI prefix corresponding to this service. This is only used to compute `cgi_path`. Leave it to `None` if not needed. | `*)`
`` | `dyn_translator : `string -> string`;` | `(*` | The function computing `cgi_path_translated` from `cgi_path`. Set it to `(fun _ -> "")` if not needed. | `*)`
`` | `dyn_accept_all_conditionals : `bool`;` | `(*` | Whether to pass requests with `If-Match` and `If-Unmodified-Since` headers to this service. If set to `true`, the service can optimize the caching behaviour by interpreting these fields. It is even obliged to interpret them. If `false`, requests containing these headers are rejected. The other condition fields `If-None-Match`, `If-Modified-Since`, and `If-Ranges` are not affected by this option. One can safely ignore these headers. | `*)`

}

    val std_activation : std_activation ->
           Nethttpd_types.extended_environment -> Netcgi.cgi_activation

Create the function for `dyn_activation` from a `std_activation` tag. Example: `let dyn_actv = std_activation `Std_activation_unbuffered`

    val dynamic_service : (#Netcgi.cgi_activation as 'a) dynamic_service ->
           [> `Dynamic_service of 'a dynamic_service ]
           Nethttpd_types.http_service

Configures the dynamic service.

    type ac_by_host_rule = [ `Allow of string list | `Deny of string list ]

Access control by host:

- ``Allow`: Only the listed hosts are allowed; all other are denied
- ``Deny`: The listed hosts are denied; all other are allowed

    type 'a ac_by_host = ac_by_host_rule * 'a Nethttpd_types.http_service

The service is protected by the access control rule

    val ac_by_host : 'a ac_by_host ->
           [> `Ac_by_host of 'a ac_by_host ]
           Nethttpd_types.http_service

Configures host-based access control

    val read_media_types_file : string -> (string * string) list

Reads a text file with two columns where the left column is the media type and the right column the corresponding suffix. Returns the contents as pairs `(suffix, type)` .

    module Debug: sig .. end