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# httpd_util (inets v9.4.2)

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Miscellaneous utility functions to be used when implementing Erlang web server API modules.

This module provides the Erlang web server API module programmer with miscellaneous utility functions.

#### Note

Note the module is only recommended for using with httpd - for other cases it should be considered as deprecated.

### See also

`httpd`

# Summary

## Functions

convert_request_date(DateString)

`convert_request_date/1` converts `DateString` to the Erlang date format. `DateString` must be in one of the three date formats defined in RFC 2616.

create_etag(FileInfo)

`create_etag/1` calculates the Etag for a file from its size and time for last modification. `FileInfo` is a record defined in `kernel/include/file.hrl`.

day(NthDayOfWeek)

`day/1` converts the day of the week (`NthDayOfWeek`) from an integer (1-7) to an abbreviated string, that is

lookup(EtsTable, Key)

Equivalent to `lookup/3`.

lookup(EtsTable, Key, Undefined)

`lookup` extracts `{Key, Value}` tuples from `ETSTable` and returns the `Value` associated with `Key`. If `ETSTable` is of type `bag`, only the first `Value` associated with `Key` is returned. `lookup/2` returns `undefined` and `lookup/3` returns `Undefined` if no `Value` is found.

lookup_mime(ConfigDB, Suffix)

Equivalent to `lookup_mime/3`.

lookup_mime(ConfigDB, Suffix, Undefined)

`lookup_mime` returns the MIME type associated with a specific file suffix as specified in the file `mime.types` (located in the config directory).

lookup_mime_default(ConfigDB, Suffix)

Equivalent to `lookup_mime_default/3`.

lookup_mime_default(ConfigDB, Suffix, Undefined)

`lookup_mime_default` returns the MIME type associated with a specific file suffix as specified in the `mime.types` file (located in the config directory). If no appropriate association is found, the value of `DefaultType` is returned.

message(StatusCode, PhraseArgs, ConfigDB)

`message/3` returns an informative HTTP 1.1 status string in HTML. Each `StatusCode` requires a specific `PhraseArgs`

month(NthMonth)

`month/1` converts the month `NthMonth` as an integer (1-12) to an abbreviated string, that is

multi_lookup(EtsTable, Key)

`multi_lookup` extracts all `{Key, Value}` tuples from an `ETSTable` and returns all `Values` associated with `Key` in a list.

reason_phrase(StatusCode)

`reason_phrase` returns `Description` of an HTTP 1.1 `StatusCode`, for example, 200 is "OK" and 201 is "Created". For more information, see RFC 2616.

rfc1123_date()

Equivalent to `rfc1123_date/1`.

rfc1123_date(LocalTime)

`rfc1123_date/0` returns the current date in RFC 1123 format. `rfc_date/1` converts the date in the Erlang format to the RFC 1123 date format.

split(String, RegExp, N)

`split/3` splits `String` in `N` chunks using `RegExp`. `split/3` is equivalent to `re:split/3` with the exception that `N` defines the maximum number of fields in `FieldList`.

split_path(URIString)

`split_path/1` splits `RequestLine` in a file reference (`Path`), and a `QueryString` or a `PathInfo` string as specified in RFC 2616. A `QueryString` is isolated from `Path` with a question mark (`?`) and `PathInfo` with a slash (/). In the case of a `QueryString`, everything before `?` is a `Path` and everything after `?` is a `QueryString`. In the case of a `PathInfo`, `RequestLine` is scanned from left-to-right on the hunt for longest possible `Path` being a file or a directory. Everything after the longest possible `Path`, isolated with a `/`, is regarded as `PathInfo`

split_script_path(URIString)

`split_script_path/1` is equivalent to `split_path/1` with one exception. If the longest possible path is not a regular, accessible, and executable file, then `not_a_script` is returned.

# Functions

# convert_request_date(DateString)

    -spec convert_request_date(DateString) -> ErlDate | bad_date
                                  when DateString :: string(), ErlDate :: calendar:datetime().

`convert_request_date/1` converts `DateString` to the Erlang date format. `DateString` must be in one of the three date formats defined in RFC 2616.

# create_etag(FileInfo)

    -spec create_etag(FileInfo) -> Etag when FileInfo :: file:file_info(), Etag :: string().

`create_etag/1` calculates the Etag for a file from its size and time for last modification. `FileInfo` is a record defined in `kernel/include/file.hrl`.

# day(NthDayOfWeek)

    -spec day(NthDayOfWeek) -> DayOfWeek when NthDayOfWeek :: 1..7, DayOfWeek :: string().

`day/1` converts the day of the week (`NthDayOfWeek`) from an integer (1-7) to an abbreviated string, that is:

1 = "Mon", 2 = "Tue", ..., 7 = "Sat".

# lookup(EtsTable, Key)

    -spec lookup(EtsTable, Key) -> Result
                    when EtsTable :: ets:table(), Key :: term(), Result :: term() | undefined.

Equivalent to `lookup/3`.

# lookup(EtsTable, Key, Undefined)

    -spec lookup(EtsTable, Key, Undefined) -> Result
                    when
                        EtsTable :: ets:table(),
                        Key :: term(),
                        Undefined :: term(),
                        Result :: term() | Undefined.

`lookup` extracts `{Key, Value}` tuples from `ETSTable` and returns the `Value` associated with `Key`. If `ETSTable` is of type `bag`, only the first `Value` associated with `Key` is returned. `lookup/2` returns `undefined` and `lookup/3` returns `Undefined` if no `Value` is found.

# lookup_mime(ConfigDB, Suffix)

    -spec lookup_mime(ConfigDB, Suffix) -> MimeType
                         when ConfigDB :: ets:tid(), Suffix :: string(), MimeType :: string() | undefined.

Equivalent to `lookup_mime/3`.

# lookup_mime(ConfigDB, Suffix, Undefined)

    -spec lookup_mime(ConfigDB, Suffix, Undefined) -> MimeType
                         when
                             ConfigDB :: ets:tid(),
                             Suffix :: string(),
                             Undefined :: term(),
                             MimeType :: string() | Undefined.

`lookup_mime` returns the MIME type associated with a specific file suffix as specified in the file `mime.types` (located in the config directory).

# lookup_mime_default(ConfigDB, Suffix)

    -spec lookup_mime_default(ConfigDB, Suffix) -> MimeType
                                 when
                                     ConfigDB :: ets:tid(),
                                     Suffix :: string(),
                                     MimeType :: string() | undefined.

Equivalent to `lookup_mime_default/3`.

# lookup_mime_default(ConfigDB, Suffix, Undefined)

    -spec lookup_mime_default(ConfigDB, Suffix, Undefined) -> MimeType
                                 when
                                     ConfigDB :: ets:tid(),
                                     Suffix :: string(),
                                     Undefined :: term(),
                                     MimeType :: string() | Undefined.

`lookup_mime_default` returns the MIME type associated with a specific file suffix as specified in the `mime.types` file (located in the config directory). If no appropriate association is found, the value of `DefaultType` is returned.

# message(StatusCode, PhraseArgs, ConfigDB)

    -spec message(StatusCode, PhraseArgs, ConfigDB) -> Message
                     when
                         StatusCode ::
                             301 | 304 | 400 | 401 | 403 | 404 | 408 | 412 | 413 | 414 | 500 | 501 | 503 |
                             504,
                         PhraseArgs :: term(),
                         ConfigDB :: ets:tid(),
                         Message :: string().

`message/3` returns an informative HTTP 1.1 status string in HTML. Each `StatusCode` requires a specific `PhraseArgs`:

- `301` - `string/0`: A URL pointing at the new document position.

- `400 | 401 | 500` - `none` (no `PhraseArgs`).

- `403 | 404` - `string/0`: A `Request-URI` as described in RFC 2616.

- `501` - `{Method, RequestURI, HTTPVersion}`: The HTTP `Method`, `Request-URI`, and `HTTP-Version` as defined in RFC 2616.

- `504` - `string/0`: A string describing why the service was unavailable.

# month(NthMonth)

    -spec month(NthMonth) -> Month when NthMonth :: 1..12, Month :: string().

`month/1` converts the month `NthMonth` as an integer (1-12) to an abbreviated string, that is:

1 = "Jan", 2 = "Feb", ..., 12 = "Dec".

# multi_lookup(EtsTable, Key)

    -spec multi_lookup(EtsTable, Key) -> Result
                          when EtsTable :: ets:tid(), Key :: term(), Result :: list() | [term()].

`multi_lookup` extracts all `{Key, Value}` tuples from an `ETSTable` and returns all `Values` associated with `Key` in a list.

# reason_phrase(StatusCode)

    -spec reason_phrase(StatusCode) -> Description
                           when
                               StatusCode ::
                                   100 | 101 | 102 | 200 | 201 | 202 | 203 | 204 | 205 | 206 | 207 | 226 |
                                   300 | 301 | 302 | 303 | 304 | 305 | 306 | 307 | 308 | 400 | 401 | 402 |
                                   403 | 404 | 405 | 406 | 407 | 408 | 409 | 410 | 411 | 412 | 413 | 414 |
                                   415 | 416 | 417 | 422 | 423 | 424 | 425 | 426 | 500 | 501 | 502 | 503 |
                                   504 | 505 | 507,
                               Description :: string().

`reason_phrase` returns `Description` of an HTTP 1.1 `StatusCode`, for example, 200 is "OK" and 201 is "Created". For more information, see RFC 2616.

# rfc1123_date()

    -spec rfc1123_date() -> RFC1123Date when RFC1123Date :: string().

Equivalent to `rfc1123_date/1`.

# rfc1123_date(LocalTime)

    -spec rfc1123_date(LocalTime) -> RFC1123Date
                          when
                              LocalTime :: calendar:datetime() | undefined,
                              RFC1123Date :: string() | undefined.

`rfc1123_date/0` returns the current date in RFC 1123 format. `rfc_date/1` converts the date in the Erlang format to the RFC 1123 date format.

# split(String, RegExp, N)

    -spec split(String, RegExp, N) -> SplitRes
                   when
                       String :: string(),
                       RegExp :: string(),
                       N :: non_neg_integer(),
                       SplitRes :: {ok, FieldList} | {error, term()},
                       FieldList :: [string()].

`split/3` splits `String` in `N` chunks using `RegExp`. `split/3` is equivalent to `re:split/3` with the exception that `N` defines the maximum number of fields in `FieldList`.

# split_path(URIString)

    -spec split_path(URIString) -> {Path, QueryStringOrPathInfo}
                        when URIString :: string(), Path :: string(), QueryStringOrPathInfo :: string().

`split_path/1` splits `RequestLine` in a file reference (`Path`), and a `QueryString` or a `PathInfo` string as specified in RFC 2616. A `QueryString` is isolated from `Path` with a question mark (`?`) and `PathInfo` with a slash (/). In the case of a `QueryString`, everything before `?` is a `Path` and everything after `?` is a `QueryString`. In the case of a `PathInfo`, `RequestLine` is scanned from left-to-right on the hunt for longest possible `Path` being a file or a directory. Everything after the longest possible `Path`, isolated with a `/`, is regarded as `PathInfo`

# split_script_path(URIString)

    -spec split_script_path(URIString) -> Split
                               when
                                   URIString :: string(),
                                   Split :: not_a_script | {Path, {PathInfo, QueryString}} | {Path, []},
                                   Path :: string(),
                                   QueryString :: string(),
                                   PathInfo :: string().

`split_script_path/1` is equivalent to `split_path/1` with one exception. If the longest possible path is not a regular, accessible, and executable file, then `not_a_script` is returned.