An implementation of an HTTP 1.1 compliant web server, as defined
in RFC 2616. Provides web server start options, administrative functions,
and an Erlang callback API.
Type definitions that are used more than once in this module:
boolean() = true | false
string() = list of ASCII characters
path() = string() representing a file or a directory
path
ip_address() = {N1,N2,N3,N4} % IPv4 |
{K1,K2,K3,K4,K5,K6,K7,K8} % IPv6
hostname() = string() representing a host, for example,
"foo.bar.com"
property() = atom()
A web server can be configured to start when starting the
Inets application, or dynamically in runtime by calling the
Inets application API inets:start(httpd, ServiceConfig) or
inets:start(httpd, ServiceConfig, How), see inets(3erl). The
configuration options, also called properties, are as follows:
File Properties
When the web server is started at application start time, the
properties are to be fetched from a configuration file that can consist of a
regular Erlang property list, that is, [{Option, Value}], where
Option = property() and Value = term(), followed by a full stop.
If the web server is started dynamically at runtime, a file can still be
specified but also the complete property list.
- {proplist_file, path()}:
- If this property is defined, Inets expects to find all other
properties defined in this file. The file must include all properties
listed under mandatory properties.
Note:
Note support for legacy configuration file with Apache syntax is dropped in
OTP-23.
Mandatory Properties
- {port, integer()} :
- The port that the HTTP server listen to. If zero is specified as port, an
arbitrary available port is picked and function httpd:info/2 can be
used to determine which port was picked.
- {server_name, string()}:
- The name of your server, normally a fully qualified domain name.
- {server_root, path()}:
- Defines the home directory of the server, where log files, and so on, can
be stored. Relative paths specified in other properties refer to this
directory.
- {document_root, path()}:
- Defines the top directory for the documents that are available on the HTTP
server.
Communication Properties
- {bind_address, ip_address() | hostname() | any}:
- Default is any
- {profile, atom()}:
- Used together with bind_address and port to uniquely
identify a HTTP server. This can be useful in a virtualized environment,
where there can be more that one server that has the same bind_address and
port. If this property is not explicitly set, it is assumed that the
bind_address and port uniquely identifies the HTTP
server.
- {socket_type, ip_comm | {ip_comm, Config::proplist()} | {ssl,
Config::proplist()}}:
- For ip_comm configuration options, see gen_tcp:listen/2, some
options that are used internally by httpd cannot be set.
For SSL configuration options, see ssl:listen/2.
Note:
OTP-25 deprecates the communication properties
{socket_type, ip_comm |
{ip_comm, Config::proplist()} | {essl, Config::proplist()}} replacing it
by
{socket_type, ip_comm | {ip_comm, Config::proplist()} | {ssl,
Config::proplist()}}.
- {ipfamily, inet | inet6}:
- Default is inet, legacy option inet6fb4 no longer makes
sense and will be translated to inet.
- {minimum_bytes_per_second, integer()}:
- If given, sets a minimum of bytes per second value for connections.
If the value is unreached, the socket closes for that
connection.
The option is good for reducing the risk of "slow DoS"
attacks.
Erlang Web Server API Modules
- {modules, [atom()]} :
- Defines which modules the HTTP server uses when handling requests. Default
is [mod_alias, mod_auth, mod_esi, mod_actions, mod_cgi, mod_dir,
mod_get, mod_head, mod_log, mod_disk_log]. Notice that some
mod-modules are dependent on others, so the order cannot be
entirely arbitrary. See the Inets Web Server Modules in the User's Guide
for details.
Limit properties
- {customize, atom()}:
- A callback module to customize the inets HTTP servers behaviour see
httpd_custom_api
- {disable_chunked_transfer_encoding_send, boolean()}:
- Allows you to disable chunked transfer-encoding when sending a response to
an HTTP/1.1 client. Default is false.
- {keep_alive, boolean()}:
- Instructs the server whether to use persistent connections when the client
claims to be HTTP/1.1 compliant. Default is true.
- {keep_alive_timeout, integer()}:
- The number of seconds the server waits for a subsequent request from the
client before closing the connection. Default is 150.
- {max_body_size, integer()}:
- Limits the size of the message body of an HTTP request. Default is no
limit.
- {max_clients, integer()}:
- Limits the number of simultaneous requests that can be supported. Default
is 150.
- {max_header_size, integer()}:
- Limits the size of the message header of an HTTP request. Default is
10240.
- {max_content_length, integer()}:
- Maximum content-length in an incoming request, in bytes. Requests with
content larger than this are answered with status 413. Default is
100000000 (100 MB).
- {max_uri_size, integer()}:
- Limits the size of the HTTP request URI. Default is no limit.
- {max_keep_alive_request, integer()}:
- The number of requests that a client can do on one connection. When the
server has responded to the number of requests defined by
max_keep_alive_requests, the server closes the connection. The
server closes it even if there are queued request. Default is no
limit.
- {max_client_body_chunk, integer()}:
- Enforces chunking of a HTTP PUT or POST body data to be delivered to the
mod_esi callback. Note this is not supported for mod_cgi. Default is no
limit e.i the whole body is delivered as one entity, which could be very
memory consuming. mod_esi(3erl).
Administrative Properties
- {mime_types, [{MimeType, Extension}] | path()}:
- MimeType = string() and Extension = string(). Files
delivered to the client are MIME typed according to RFC 1590. File
suffixes are mapped to MIME types before file delivery. The mapping
between file suffixes and MIME types can be specified in the property
list.
Default is
[{"html","text/html"},{"htm","text/html"}].
- {mime_type, string()}:
- When the server is asked to provide a document type that cannot be
determined by the MIME Type Settings, the server uses this default
type.
- {server_admin, string()}:
- Defines the email-address of the server administrator to be included in
any error messages returned by the server.
- {server_tokens, none|prod|major|minor|minimal|os|full|{private,
string()}}:
- Defines the look of the value of the server header.
Example: Assuming the version of Inets is 5.8.1, the server
header string can look as follows for the different values of
server-tokens:
- none:
- "" % A Server: header will not be generated
- prod:
- "inets"
- major:
- "inets/5"
- minor:
- "inets/5.8"
- minimal:
- "inets/5.8.1"
- os:
- "inets/5.8.1 (unix)"
- full:
- "inets/5.8.1 (unix/linux) OTP/R15B"
- {private, "foo/bar"}:
- "foo/bar"
By default, the value is as before, that is, minimal.
- {logger, Options::list()}:
- Currently only one option is supported:
- {error, ServerID::atom()}:
- Produces logger events on logger level error under the hierarchical logger
domain: [otp, inets, httpd, ServerID, error] The built in logger
formatting function produces log entries from the error reports:
#{server_name => string()
protocol => internal | 'TCP' | 'TLS' | 'HTTP',
transport => "TCP "| "TLS", %% Present when protocol = 'HTTP'
uri => string(), %% Present when protocol = 'HTTP' and URI is valid
peer => inet:peername(),
host => inet:hostname(),
reason => term()
}
An example of a log entry with only default settings of logger
=ERROR REPORT==== 9-Oct-2019::09:33:27.350235 ===
Server: My Server
Protocol: HTTP
Transport: TLS
URI: /not_there
Host: 127.0.1.1:80
Peer: 127.0.0.1:45253
Reason: [{statuscode,404},{description,"Object Not Found"}]
Using this option makes mod_log and mod_disk_log error logs
redundant.
{fun logger_filters:domain/2,
{log,equal,[otp,inets, httpd, ServerID, error]}
[{kernel,
[{logger,
[{handler, http_error_test, logger_std_h,
#{config => #{ file => "log/http_error.log" },
filters => [{inets_httpd, {fun logger_filters:domain/2,
{log, equal,
[otp, inets, httpd, my_server, error]
}}}],
filter_default => stop }}]}]}].
or if you want to add it to the default logger via an API:
logger:add_handler_filter(default,
inets_httpd,
{fun logger_filters:domain/2,
{log, equal,
[otp, inets, httpd, my_server, error]}}).
- {log_format, common | combined}:
- Defines if access logs are to be written according to the common
log format or the extended common log format. The common format is
one line looking like this: remotehost rfc931 authuser [date]
"request" status bytes.
- remotehost:
- Remote.
- rfc931:
- The remote username of the client (RFC 931).
- authuser:
- The username used for authentication.
- [date]:
- Date and time of the request (RFC 1123).
- "request":
- The request line as it came from the client (RFC 1945).
- status:
- The HTTP status code returned to the client (RFC 1945).
- bytes:
- The content-length of the document transferred.
The combined format is one line looking like this:
remotehost rfc931 authuser [date] "request" status bytes
"referer" "user_agent"
In addition to the earlier:
- "referer":
- The URL the client was on before requesting the URL (if it could not be
determined, a minus sign is placed in this field).
- "user_agent":
- The software the client claims to be using (if it could not be determined,
a minus sign is placed in this field).
This affects the access logs written by mod_log and
mod_disk_log.
- {error_log_format, pretty | compact}:
- Default is pretty. If the error log is meant to be read directly by
a human, pretty is the best option.
pretty has a format corresponding to:
io:format("[~s] ~s, reason: ~n ~p ~n~n", [Date, Msg, Reason]).
compact has a format corresponding to:
io:format("[~s] ~s, reason: ~w ~n", [Date, Msg, Reason]).
This affects the error logs written by mod_log and
mod_disk_log.
URL Aliasing Properties - Requires mod_alias
- {alias, {Alias, RealName}}:
- Alias = string() and RealName = string(). alias
allows documents to be stored in the local file system instead of the
document_root location. URLs with a path beginning with url-path is
mapped to local files beginning with directory-filename, for example:
{alias, {"/image", "/ftp/pub/image"}}
Access to http://your.server.org/image/foo.gif would refer to the
file /ftp/pub/image/foo.gif.
- {re_write, {Re, Replacement}}:
- Re = string() and Replacement = string(). re_write
allows documents to be stored in the local file system instead of the
document_root location. URLs are rewritten by re:replace/3
to produce a path in the local file-system, for example:
{re_write, {"^/[~]([^/]+)(.*)$", "/home/\\1/public\\2"}}
Access to http://your.server.org/~bob/foo.gif would refer to the
file /home/bob/public/foo.gif.
- {directory_index, [string()]}:
- directory_index specifies a list of resources to look for if a
client requests a directory using a / at the end of the directory
name. file depicts the name of a file in the directory. Several
files can be given, in which case the server returns the first it finds,
for example:
{directory_index, ["index.html", "welcome.html"]}
Access to http://your.server.org/docs/ would return
http://your.server.org/docs/index.html or
http://your.server.org/docs/welcome.html if index.html does not exist.
CGI Properties - Requires mod_cgi
- {script_alias, {Alias, RealName}}:
- Alias = string() and RealName = string(). Have the same
behavior as property alias, except that they also mark the target
directory as containing CGI scripts. URLs with a path beginning with
url-path are mapped to scripts beginning with directory-filename, for
example:
{script_alias, {"/cgi-bin/", "/web/cgi-bin/"}}
Access to http://your.server.org/cgi-bin/foo would cause the
server to run the script /web/cgi-bin/foo.
- {script_re_write, {Re, Replacement}}:
- Re = string() and Replacement = string(). Have the same
behavior as property re_write, except that they also mark the
target directory as containing CGI scripts. URLs with a path beginning
with url-path are mapped to scripts beginning with directory-filename, for
example:
{script_re_write, {"^/cgi-bin/(\\d+)/", "/web/\\1/cgi-bin/"}}
Access to http://your.server.org/cgi-bin/17/foo would cause the
server to run the script /web/17/cgi-bin/foo.
- {script_nocache, boolean()}:
- If script_nocache is set to true, the HTTP server by default
adds the header fields necessary to prevent proxies from caching the page.
Generally this is preferred. Default to false.
- {script_timeout, integer()}:
- The time in seconds the web server waits between each chunk of data from
the script. If the CGI script does not deliver any data before the
timeout, the connection to the client is closed. Default is
15.
- {action, {MimeType, CgiScript}} - requires mod_action:
- MimeType = string() and CgiScript = string(). action
adds an action activating a CGI script whenever a file of a certain MIME
type is requested. It propagates the URL and file path of the requested
document using the standard CGI PATH_INFO and PATH_TRANSLATED environment
variables.
{action, {"text/plain", "/cgi-bin/log_and_deliver_text"}}
- {script, {Method, CgiScript}} - requires mod_action:
- Method = string() and CgiScript = string(). script
adds an action activating a CGI script whenever a file is requested using
a certain HTTP method. The method is either GET or POST, as defined in RFC
1945. It propagates the URL and file path of the requested document using
the standard CGI PATH_INFO and PATH_TRANSLATED environment variables.
{script, {"PUT", "/cgi-bin/put"}}
ESI Properties - Requires mod_esi
- {erl_script_alias, {URLPath, [AllowedModule]}}:
- URLPath = string() and AllowedModule = atom().
erl_script_alias marks all URLs matching url-path as erl scheme
scripts. A matching URL is mapped into a specific module and function, for
example:
{erl_script_alias, {"/cgi-bin/example", [httpd_example]}}
A request to
http://your.server.org/cgi-bin/example/httpd_example:yahoo would refer to
httpd_example:yahoo/3 or, if that does not exist, httpd_example:yahoo/2 and
http://your.server.org/cgi-bin/example/other:yahoo would not be allowed to
execute.
- {erl_script_nocache, boolean()}:
- If erl_script_nocache is set to true, the server adds HTTP
header fields preventing proxies from caching the page. This is generally
a good idea for dynamic content, as the content often varies between each
request. Default is false.
- {erl_script_timeout, integer()}:
- If erl_script_timeout sets the time in seconds the server waits
between each chunk of data to be delivered through
mod_esi:deliver/2. Default is 15. This is only relevant for
scripts that use the erl scheme.
Log Properties - Requires mod_log
- {error_log, path()}:
- Defines the filename of the error log file to be used to log server
errors. If the filename does not begin with a slash (/), it is assumed to
be relative to the server_root.
- {security_log, path()}:
- Defines the filename of the access log file to be used to log security
events. If the filename does not begin with a slash (/), it is assumed to
be relative to the server_root.
- {transfer_log, path()}:
- Defines the filename of the access log file to be used to log incoming
requests. If the filename does not begin with a slash (/), it is assumed
to be relative to the server_root.
Disk Log Properties - Requires mod_disk_log
- {disk_log_format, internal | external}:
- Defines the file format of the log files. See disk_log for details.
If the internal file format is used, the log file is repaired after a
crash. When a log file is repaired, data can disappear. When the external
file format is used, httpd does not start if the log file is
broken. Default is external.
- {error_disk_log, path()}:
- Defines the filename of the (disk_log(3erl)) error log file to be
used to log server errors. If the filename does not begin with a slash
(/), it is assumed to be relative to the server_root.
- {error_disk_log_size, {MaxBytes, MaxFiles}}:
- MaxBytes = integer() and MaxFiles = integer(). Defines the
properties of the (disk_log(3erl)) error log file. This file is of
type wrap log and max bytes is written to each file and max files is used
before the first file is truncated and reused.
- {security_disk_log, path()}:
- Defines the filename of the (disk_log(3erl)) access log file
logging incoming security events, that is, authenticated requests. If the
filename does not begin with a slash (/), it is assumed to be relative to
the server_root.
- {security_disk_log_size, {MaxBytes, MaxFiles}}:
- MaxBytes = integer() and MaxFiles = integer(). Defines the
properties of the disk_log(3erl) access log file. This file is of
type wrap log and max bytes is written to each file and max files is used
before the first file is truncated and reused.
- {transfer_disk_log, path()}:
- Defines the filename of the (disk_log(3erl)) access log file
logging incoming requests. If the filename does not begin with a slash
(/), it is assumed to be relative to the server_root.
- {transfer_disk_log_size, {MaxBytes, MaxFiles}}:
- MaxBytes = integer() and MaxFiles = integer(). Defines the
properties of the disk_log(3erl) access log file. This file is of
type wrap log and max bytes is written to each file and max files is used
before the first file is truncated and reused.
Authentication Properties - Requires mod_auth
{directory, {path(), [{property(), term()}]}}
The properties for directories are as follows:
- {allow_from, all | [RegxpHostString]}:
- Defines a set of hosts to be granted access to a given directory, for
example:
{allow_from, ["123.34.56.11", "150.100.23"]}
The host 123.34.56.11 and all machines on the
150.100.23 subnet are allowed access.
- {deny_from, all | [RegxpHostString]}:
- Defines a set of hosts to be denied access to a given directory, for
example:
{deny_from, ["123.34.56.11", "150.100.23"]}
The host 123.34.56.11 and all machines on the
150.100.23 subnet are not allowed access.
- {auth_type, plain | dets | mnesia}:
- Sets the type of authentication database that is used for the directory.
The key difference between the different methods is that dynamic data can
be saved when Mnesia and Dets are used.
- {auth_user_file, path()}:
- Sets the name of a file containing the list of users and passwords for
user authentication. The filename can be either absolute or relative to
the server_root. If using the plain storage method, this file is a
plain text file where each line contains a username followed by a colon,
followed by the non-encrypted password. If usernames are duplicated, the
behavior is undefined.
ragnar:s7Xxv7
edward:wwjau8
If the Dets storage method is used, the user database is
maintained by Dets and must not be edited by hand. Use the API functions in
module mod_auth to create/edit the user database. This directive is
ignored if the Mnesia storage method is used. For security reasons, ensure
that auth_user_file is stored outside the document tree of the web
server. If it is placed in the directory that it protects, clients can
download it.
- {auth_group_file, path()}:
- Sets the name of a file containing the list of user groups for user
authentication. The filename can be either absolute or relative to the
server_root. If the plain storage method is used, the group file is
a plain text file, where each line contains a group name followed by a
colon, followed by the members usernames separated by spaces.
group1: bob joe ante
If the Dets storage method is used, the group database is
maintained by Dets and must not be edited by hand. Use the API for module
mod_auth to create/edit the group database. This directive is ignored
if the Mnesia storage method is used. For security reasons, ensure that the
auth_group_file is stored outside the document tree of the web
server. If it is placed in the directory that it protects, clients can
download it.
- {auth_name, string()}:
- Sets the name of the authorization realm (auth-domain) for a directory.
This string informs the client about which username and password to
use.
- {auth_access_password, string()}:
- If set to other than "NoPassword", the password is required for
all API calls. If the password is set to "DummyPassword", the
password must be changed before any other API calls. To secure the
authenticating data, the password must be changed after the web server is
started. Otherwise it is written in clear text in the configuration
file.
- {require_user, [string()]}:
- Defines users to grant access to a given directory using a secret
password.
- {require_group, [string()]}:
- Defines users to grant access to a given directory using a secret
password.
Security Properties - Requires mod_security
{security_directory, {path(), [{property(), term()}]}}
The properties for the security directories are as follows:
- {data_file, path()}:
- Name of the security data file. The filename can either be absolute or
relative to the server_root. This file is used to store persistent
data for module mod_security.
- {max_retries, integer()}:
- Specifies the maximum number of attempts to authenticate a user before the
user is blocked out. If a user successfully authenticates while blocked,
the user receives a 403 (Forbidden) response from the server. If the user
makes a failed attempt while blocked, the server returns 401
(Unauthorized), for security reasons. Default is 3. Can be set to
infinity.
- {block_time, integer()}:
- Specifies the number of minutes a user is blocked. After this time has
passed, the user automatically regains access. Default is 60.
- {fail_expire_time, integer()}:
- Specifies the number of minutes a failed user authentication is
remembered. If a user authenticates after this time has passed, the
previous failed authentications are forgotten. Default is 30.
- {auth_timeout, integer()}:
-
Specifies the number of seconds a successful user authentication is
remembered. After this time has passed, the authentication is no longer
reported. Default is 30.
info(Pid) -> HttpInformation
info(Pid, Properties) -> HttpInformation
Types:
Pid = pid()
Properties = [atom()]
HttpInformation =
[CommonOption] |
[CommunicationOption] |
[ModOption] |
[LimitOption] |
[AdminOption]
CommonOption =
{port, integer() >= 0} |
{server_name, string()} |
{server_root, Path} |
{document_root, Path}
CommunicationOption =
{bind_address, inet:ip_address() | inet:hostname() | any} |
{profile, atom()} |
{socket_type,
ip_comm |
{ip_comm, ssl:tls_option() | gen_tcp:option()} |
{ssl, ssl:tls_option() | gen_tcp:option()}} |
{ipfamily, inet | inet6} |
{minimum_bytes_per_second, integer()}
ModOption = {modules, atom()}
LimitOption =
{customize, atom()} |
{disable_chunked_transfer_encoding_send, boolean()} |
{keep_alive, boolean()} |
{keep_alive_timeout, integer()} |
{max_body_size, integer()} |
{max_clients, integer()} |
{max_header_size, integer()} |
{max_content_length, integer()} |
{max_uri_size, integer()} |
{max_keep_alive_request, integer()} |
{max_client_body_chunk, integer()}
AdminOption =
{mime_types,
[{MimeType :: string(), Extension :: string()}] | Path} |
{mime_type, string()} |
{server_admin, string()} |
{server_tokens,
none | prod | major | minor | minimal | os | full |
{private, string()}} |
{logger, Options :: list()} |
{log_format, common | combined} |
{error_log_format, pretty | compact}
Fetches information about the HTTP server. When called with only
the pid, all properties are fetched. When called with a list of specific
properties, they are fetched. The available properties are the same as the
start options of the server.
Note:
Pid is the pid returned from
inets:start/[2,3]. Can also be retrieved
form
inets:services/0 and
inets:services_info/0, see
inets(3erl).
info(Address, Port) -> HttpInformation
info(Address, Port, Profile) -> HttpInformation
info(Address, Port, Properties) -> HttpInformation
info(Address, Port, Profile, Properties) -> HttpInformation
Types:
Address = inet:ip_address() | any
Port = integer()
Profile = atom()
Properties = [atom()]
Path = file:name_all()
HttpInformation =
[CommonOption] |
[CommunicationOption] |
[ModOption] |
[LimitOption] |
[AdminOption]
CommonOption =
{port, integer() >= 0} |
{server_name, string()} |
{server_root, Path} |
{document_root, Path}
CommunicationOption =
{bind_address, inet:ip_address() | inet:hostname() | any} |
{profile, atom()} |
{socket_type,
ip_comm |
{ip_comm, ssl:tls_option() | gen_tcp:option()} |
{ssl, ssl:tls_option() | gen_tcp:option()}} |
{ipfamily, inet | inet6} |
{minimum_bytes_per_second, integer()}
ModOption = {modules, atom()}
LimitOption =
{customize, atom()} |
{disable_chunked_transfer_encoding_send, boolean()} |
{keep_alive, boolean()} |
{keep_alive_timeout, integer()} |
{max_body_size, integer()} |
{max_clients, integer()} |
{max_header_size, integer()} |
{max_content_length, integer()} |
{max_uri_size, integer()} |
{max_keep_alive_request, integer()} |
{max_client_body_chunk, integer()}
AdminOption =
{mime_types,
[{MimeType :: string(), Extension :: string()}] | Path} |
{mime_type, string()} |
{server_admin, string()} |
{server_tokens,
none | prod | major | minor | minimal | os | full |
{private, string()}} |
{logger, Options :: list()} |
{log_format, common | combined} |
{error_log_format, pretty | compact}
Fetches information about the HTTP server. When called with only
Address and Port, all properties are fetched. When called with
a list of specific properties, they are fetched. The available properties
are the same as the start options of the server.
Note:
The
Address must be the IP address and cannot be the hostname.
reload_config(Config, Mode) -> ok | {error, Reason} | no_return()
Types:
Config = file:name_all() | [{Option, Value}]
Mode = non_disturbing | disturbing | blocked
Option = atom()
Value = Reason = term()
Reloads the HTTP server configuration without restarting the
server. Incoming requests are answered with a temporary down message during
the reload time.
Note:
Available properties are the same as the start options of the server, but the
properties
bind_address and
port cannot be changed.
If mode is disturbing, the server is blocked forcefully, all
ongoing requests terminates, and the reload starts immediately. If mode is
non-disturbing, no new connections are accepted, but ongoing requests are
allowed to complete before the reload is done.
The Erlang web server API data types are as follows:
ModData = #mod{}
-record(mod, {
data = [],
socket_type = ip_comm,
socket,
config_db,
method,
absolute_uri,
request_uri,
http_version,
request_line,
parsed_header = [],
entity_body,
connection
}).
To access the record in your callback-module use:
-include_lib("inets/include/httpd.hrl").
The fields of record mod have the following meaning:
- data:
- Type [{InteractionKey,InteractionValue}] is used to propagate data
between modules. Depicted interaction_data() in function type
declarations.
- socket_type:
- socket_type() indicates whether it is an IP socket or an ssl
socket.
- socket:
- The socket, in format ip_comm or ssl, depending on
socket_type.
- config_db:
- The config file directives stored as key-value tuples in an ETS table.
Depicted config_db() in function type declarations.
- method:
- Type "GET" | "POST" | "HEAD" |
"TRACE", that is, the HTTP method.
- absolute_uri:
- If the request is an HTTP/1.1 request, the URI can be in the absolute URI
format. In that case, httpd saves the absolute URI in this field.
An Example of an absolute URI is
"http://ServerName:Part/cgi-bin/find.pl?person=jocke"
- request_uri:
- The Request-URI as defined in RFC 1945, for example,
"/cgi-bin/find.pl?person=jocke".
- http_version:
- The HTTP version of the request, that is, "HTTP/1.0", or
"HTTP/1.1".
- request_line:
- The Request-Line as defined inRFC 1945, for example, "GET
/cgi-bin/find.pl?person=jocke HTTP/1.0".
- Type [{HeaderKey,HeaderValue}]. parsed_header contains all
HTTP header fields from the HTTP request stored in a list as key-value
tuples. See RFC 2616 for a listing of all header fields. For example, the
date field is stored as {"date","Wed, 15 Oct 1997
14:35:17 GMT"}. RFC 2616 defines that HTTP is a case-insensitive
protocol and the header fields can be in lower case or upper case.
httpd ensures that all header field names are in lower case.
- entity_body:
- The entity-Body as defined in RFC 2616, for example, data sent from
a CGI script using the POST method.
- connection:
- true | false. If set to true, the connection to the client
is a persistent connection and is not closed when the request is
served.
Module:do(ModData)-> {proceed, OldData} | {proceed, NewData}
| {break, NewData} | done
Types:
OldData = list()
NewData = [{response,{StatusCode,Body}}]
| [{response,{response,Head,Body}}]
| [{response,{already_sent,Statuscode,Size}}]
StatusCode = integer()
Body = io_list() | nobody | {Fun, Arg}
Head = [HeaderOption]
HeaderOption = {Option, Value} | {code, StatusCode}
Option = accept_ranges | allow
| cache_control | content_MD5
| content_encoding | content_language
| content_length | content_location
| content_range | content_type | date
| etag | expires | last_modified
| location | pragma | retry_after
| server | trailer | transfer_encoding
Value = string()
Fun = fun( Arg ) -> sent| close | Body
Arg = [term()]
When a valid request reaches httpd, it calls do/1 in
each module, defined by the configuration option of Module. The
function can generate data for other modules or a response that can be sent
back to the client.
The field data in ModData is a list. This list is
the list returned from the last call to do/1.
Body is the body of the HTTP response that is sent back to
the client. An appropriate header is appended to the message.
StatusCode is the status code of the response, see RFC 2616 for the
appropriate values.
Head is a key value list of HTTP header fields. The server
constructs an HTTP header from this data. See RFC 2616 for the appropriate
value for each header field. If the client is an HTTP/1.0 client, the server
filters the list so that only HTTP/1.0 header fields are sent back to the
client.
If Body is returned and equal to {Fun,Arg}, the web
server tries apply/2 on Fun with Arg as argument. The
web server expects that the fun either returns a list (Body) that is
an HTTP response, or the atom sent if the HTTP response is sent back
to the client. If close is returned from the fun, something has gone
wrong and the server signals this to the client by closing the
connection.
Module:remove(ConfigDB) -> ok | {error, Reason}
Types:
ConfigDB = ets_table()
Reason = term()
When httpd is shut down, it tries to execute
remove/1 in each Erlang web server callback module. The programmer
can use this function to clean up resources created in the store
function.
Module:store({Option, Value}, Config)-> {ok, {Option,
NewValue}} | {error, Reason}
Types:
Line = string()
Option = property()
Config = [{Option, Value}]
Value = term()
Reason = term()
Checks the validity of the configuration options before saving
them in the internal database. This function can also have a side effect,
that is, setup of necessary extra resources implied by the configuration
option. It can also resolve possible dependencies among configuration
options by changing the value of the option. This function only needs
clauses for the options implemented by this particular callback module.
parse_query(QueryString) -> QueryList | uri_string:error()
Types:
QueryString = string()
QueryList = [{unicode:chardata(), unicode:chardata() | true}]
parse_query/1 parses incoming data to erl and
eval scripts (see mod_esi(3erl)) as defined in the standard URL
format, that is, '+' becomes 'space' and decoding of hexadecimal characters
(%xx).