View Source httpc (inets v9.2)
An HTTP/1.1 client
This module provides the API to an HTTP/1.1 compatible client according to RFC 2616. Caching is not supported.
Note
When starting the
Inetsapplication, a manager process for the default profile is started. The functions in this API that do not explicitly use a profile accesses the default profile. A profile keeps track of proxy options, cookies, and other options that can be applied to more than one request.If the scheme
httpsis used, theSSLapplication must be started. Whenhttpslinks need to go through a proxy, the CONNECT method extension to HTTP-1.1 is used to establish a tunnel and then the connection is upgraded to TLS. However, "TLS upgrade" according to RFC 2817is not supported.Pipelining is only used if the pipeline time-out is set, otherwise persistent connections without pipelining are used. That is, the client always waits for the previous response before sending the next request.
Some examples are provided in the Inets User's Guide.
HTTP CLIENT SERVICE START/STOP
An HTTP client can be configured to start when starting the Inets application
or started dynamically in runtime by calling the Inets application API
inets:start(httpc, ServiceConfig) or inets:start(httpc, ServiceConfig, How),
see inets. The configuration options are as follows:
{profile, Profile :: atom() | pid()} - Name of the profile. This option is mandatory.
{data_dir, Path :: string()} - Directory where the profile can save persistent data. If omitted, all cookies are treated as session cookies.
Pathrepresents a file path or directory path.
The client can be stopped using inets:stop(httpc, Pid) or
inets:stop(httpc, Profile).
Warning
Please note that
httpcnormalizes input URIs before internal processing and special care shall be taken when the URI has percent ("%") characters. A percent serves as the indicator for percent-encoded octets and it must be percent-encoded as "%25" for that octet to be used as data within the URI.For example, in order to send an
HTTP GETrequest with the URIhttp://localhost/foo%25bar, the percent character must be percent-encoded when creating the request:httpc:request("http://localhost/foo%2525bar").
SEE ALSO
Summary
Functions
Equivalent to cancel_request/2.
Cancels an asynchronous HTTP request. Notice that this does not guarantee that the request response is not delivered. Because it is asynchronous, the request can already have been completed when the cancellation arrives.
Equivalent to cookie_header/2.
Returns the cookie header that would have been sent when making a request to
Url using profile Profile. If no profile is specified, the default profile
is used.
Returns the cookie header that would have been sent when making a request to
Url using profile Profile. If no profile is specified, the default profile
is used.
Equivalent to get_options/2.
Retrieves the options currently used by the client.
Produces a list of miscellaneous information. Intended for debugging. If no profile is specified, the default profile is used.
Equivalent to request/2.
Equivalent to httpc:request(get, {Url, []}, [], []).
Equivalent to request/5.
Sends an HTTP request. The function can be both synchronous and asynchronous. In
the latter case, the function returns {ok, RequestId} and then the information
is delivered to the receiver depending on that value.
Equivalent to reset_cookies/1.
Resets (clears) the cookie database for the specified Profile. If no profile
is specified the default profile is used.
Equivalent to set_options/2.
Sets options to be used for subsequent requests.
Returns ssl options which can be used to verify the host, uses
public_key:cacerts_get() to read CA certicates
and if WildcardHostName is true adds the hostname check from
public_key:public_key:pkix_verify_hostname_match_fun(https)
to the options.
Equivalent to store_cookies/3.
Saves the cookies defined in SetCookieHeaders in the client profile cookie
database. Call this function if option cookies is set to verify. If no
profile is specified, the default profile is used.
Triggers the next message to be streamed, that is, the same behavior as active ones for sockets.
Equivalent to which_cookies/1.
Produces a list of the entire cookie database. Intended for debugging/testing purposes. If no profile is specified, the default profile is used.
Equivalent to which_sessions/1.
This function is intended for debugging only. It produces a slightly processed dump of the session database. The first list of the session information tuple will contain session information on an internal format. The last two lists of the session information tuple should always be empty if the code is working as intended. If no profile is specified, the default profile is used.
Functions
-spec cancel_request(RequestId) -> ok when RequestId :: any().
Equivalent to cancel_request/2.
Cancels an asynchronous HTTP request. Notice that this does not guarantee that the request response is not delivered. Because it is asynchronous, the request can already have been completed when the cancellation arrives.
-spec cookie_header(Url) -> HttpHeader | {error, Reason} when Url :: uri_string:uri_string(), HttpHeader :: {Field :: [byte()], Value :: binary() | iolist()}, Reason :: term().
Equivalent to cookie_header/2.
-spec cookie_header(Url, ProfileOrOpts) -> HttpHeader | {error, Reason} when Url :: uri_string:uri_string(), HttpHeader :: {Field :: [byte()], Value :: binary() | iolist()}, ProfileOrOpts :: Profile | Opts, Profile :: atom() | pid(), Opts :: [CookieHeaderOpt], CookieHeaderOpt :: {ipv6_host_with_brackets, boolean()}, Reason :: term().
Returns the cookie header that would have been sent when making a request to
Url using profile Profile. If no profile is specified, the default profile
is used.
Option ipv6_host_with_bracket deals with how to parse IPv6 addresses. For
details, see argument Options of request/4,5.
-spec cookie_header(Url, Opts, Profile) -> HttpHeader | {error, Reason} when Url :: uri_string:uri_string(), HttpHeader :: {Field :: [byte()], Value :: binary() | iolist()}, Profile :: atom() | pid(), Opts :: [CookieHeaderOpt], CookieHeaderOpt :: {ipv6_host_with_brackets, boolean()}, Reason :: term().
Returns the cookie header that would have been sent when making a request to
Url using profile Profile. If no profile is specified, the default profile
is used.
Option ipv6_host_with_bracket deals with how to parse IPv6 addresses. For
details, see argument Options of request/4,5.
-spec get_options(OptionItems) -> {ok, Values} | {error, Reason} when OptionItems :: all | [OptionItem], OptionItem :: proxy | https_proxy | max_sessions | keep_alive_timeout | max_keep_alive_length | pipeline_timeout | max_pipeline_length | cookies | ipfamily | ip | port | socket_opts | verbose | unix_socket, Values :: [{OptionItem, term()}], Reason :: term().
Equivalent to get_options/2.
-spec get_options(OptionItems, Profile) -> {ok, Values} | {error, Reason} when OptionItems :: all | [OptionItem], OptionItem :: proxy | https_proxy | max_sessions | keep_alive_timeout | max_keep_alive_length | pipeline_timeout | max_pipeline_length | cookies | ipfamily | ip | port | socket_opts | verbose | unix_socket, Values :: [{OptionItem, term()}], Profile :: atom() | pid(), Reason :: term().
Retrieves the options currently used by the client.
Equivalent to info/1.
Produces a list of miscellaneous information. Intended for debugging. If no profile is specified, the default profile is used.
-spec request(uri_string:uri_string()) -> {ok, Result} | {error, term()} when Result :: {StatusLine :: {HttpVersion, StatusCode, string()}, [HttpHeader], HttpBodyResult} | {StatusCode, HttpBodyResult} | RequestId | saved_to_file, HttpBodyResult :: uri_string:uri_string() | binary(), HttpVersion :: uri_string:uri_string(), StatusCode :: non_neg_integer(), HttpHeader :: {Field :: [byte()], Value :: binary() | iolist()}, RequestId :: any().
Equivalent to request/2.
-spec request(Url, Profile) -> {ok, Result} | {error, term()} when Url :: uri_string:uri_string(), Profile :: atom() | pid(), Result :: {StatusLine, [HttpHeader], HttpBodyResult} | {StatusCode, HttpBodyResult} | RequestId | saved_to_file, HttpHeader :: {Field :: [byte()], Value :: binary() | iolist()}, HttpBodyResult :: uri_string:uri_string() | binary(), StatusLine :: {HttpVersion, StatusCode, string()}, HttpVersion :: uri_string:uri_string(), StatusCode :: non_neg_integer(), RequestId :: any().
Equivalent to httpc:request(get, {Url, []}, [], []).
-spec request(Method, Request, HttpOptions, Options) -> {ok, Result} | {error, term()} when Method :: head | get | put | patch | post | trace | options | delete, Request :: {uri_string:uri_string(), [HttpHeader]} | {uri_string:uri_string(), [HttpHeader], ContentType :: uri_string:uri_string(), HttpBody}, HttpBody :: iolist() | binary() | {fun((Accumulator :: term()) -> eof | {ok, iolist(), Accumulator :: term()}), Accumulator :: term()} | {chunkify, fun((Accumulator :: term()) -> eof | {ok, iolist(), Accumulator :: term()}), Accumulator :: term()}, HttpOptions :: [HttpOption], HttpOption :: {timeout, timeout()} | {connect_timeout, timeout()} | {ssl, [ssl:tls_option()]} | {autoredirect, boolean()} | {proxy_auth, {string(), string()}} | {version, HttpVersion} | {relaxed, boolean()}, Options :: [OptionRequest], OptionRequest :: {sync, boolean()} | {stream, StreamTo} | {body_format, BodyFormat} | {full_result, boolean()} | {headers_as_is, boolean()} | {socket_opts, [SocketOpt]} | {receiver, Receiver} | {ipv6_host_with_brackets, boolean()}, StreamTo :: none | self | {self, once} | file:name_all(), SocketOpt :: term(), BodyFormat :: string | binary, Receiver :: pid() | fun((term()) -> term()) | {ReceiverModule :: atom(), ReceiverFunction :: atom(), ReceiverArgs :: list()}, Result :: {StatusLine, [HttpHeader], HttpBodyResult} | {StatusCode, HttpBodyResult} | RequestId | saved_to_file, StatusCode :: non_neg_integer(), StatusLine :: {HttpVersion, StatusCode, string()}, HttpVersion :: uri_string:uri_string(), HttpHeader :: {Field :: [byte()], Value :: binary() | iolist()}, HttpBodyResult :: uri_string:uri_string() | binary(), RequestId :: any().
Equivalent to request/5.
request(Method, Request, HttpOptions, Options, Profile)
View Source (since OTP R13B04)-spec request(Method, Request, HttpOptions, Options, Profile) -> {ok, Result} | {error, term()} when Method :: head | get | put | patch | post | trace | options | delete, Request :: {uri_string:uri_string(), [HttpHeader]} | {uri_string:uri_string(), [HttpHeader], ContentType :: uri_string:uri_string(), HttpBody}, HttpBody :: iolist() | binary() | {fun((Accumulator :: term()) -> eof | {ok, iolist(), Accumulator :: term()}), Accumulator :: term()} | {chunkify, fun((Accumulator :: term()) -> eof | {ok, iolist(), Accumulator :: term()}), Accumulator :: term()}, HttpHeader :: {Field :: [byte()], Value :: binary() | iolist()}, HttpOptions :: [HttpOption], HttpOption :: {timeout, timeout()} | {connect_timeout, timeout()} | {ssl, [ssl:tls_option()]} | {autoredirect, boolean()} | {proxy_auth, {string(), string()}} | {version, HttpVersion} | {relaxed, boolean()}, Options :: [OptionRequest], OptionRequest :: {sync, boolean()} | {stream, StreamTo} | {body_format, BodyFormat} | {full_result, boolean()} | {headers_as_is, boolean()} | {socket_opts, [SocketOpt]} | {receiver, Receiver} | {ipv6_host_with_brackets, boolean()}, StreamTo :: none | self | {self, once} | file:name_all(), BodyFormat :: string | binary, SocketOpt :: term(), Receiver :: pid() | fun((term()) -> term()) | {ReceiverModule :: atom(), ReceiverFunction :: atom(), ReceiverArgs :: list()}, Profile :: atom() | pid(), HttpVersion :: uri_string:uri_string(), Result :: {StatusLine, [HttpHeader], HttpBodyResult} | {StatusCode, HttpBodyResult} | RequestId | saved_to_file, StatusLine :: {HttpVersion, StatusCode, string()}, StatusCode :: non_neg_integer(), HttpBodyResult :: uri_string:uri_string() | binary(), RequestId :: any().
Sends an HTTP request. The function can be both synchronous and asynchronous. In
the latter case, the function returns {ok, RequestId} and then the information
is delivered to the receiver depending on that value.
When Profile is stand_alone only the pid can be used.
HTTP options:
timeout- Time-out time for the request.The clock starts ticking when the request is sent.
Time is in milliseconds.
Default is
infinity.connect_timeout- Connection time-out time, used during the initial request, when the client is connecting to the server.Time is in milliseconds.
Default is the value of option
timeout.ssl- This is theSSL/TLSconnecting configuration option.Default value is obtained by calling
httpc:ssl_verify_host_options(true). . See ssl:connect/2,3,4 for available options.autoredirect- The client automatically retrieves the information from the new URI and returns that as the result, instead of a 30X-result code.For some 30X-result codes, automatic redirect is not allowed. In these cases the 30X-result is always returned.
Default is
true.proxy_auth- A proxy-authorization header using a tuple where the first element is theusernameand the second element of the tuple is thepasswordadded to the request.version- Can be used to make the client act as anHTTP/1.0client. By default this is anHTTP/1.1client. When usingHTTP/1.0persistent connections are not used.Default is the string
"HTTP/1.1".relaxed- If set totrue, workarounds for known server deviations from the HTTP-standard are enabled.Default is
false.
Options details:
sync- Option for the request to be synchronous or asynchronous.Default is
true.stream- Streams the body of a 200 or 206 response to the calling process or to a file. When streaming to the calling process using optionself, the following stream messages are sent to that process:{http, {RequestId, stream_start, Headers}}, {http, {RequestId, stream, BinBodyPart}}, and {http, {RequestId, stream_end, Headers}}.When streaming to the calling processes using option
{self, once}, the first message has an extra element, that is,{http, {RequestId, stream_start, Headers, Pid}}. This is the process id to be used as an argument tohttpc:stream_next/1to trigger the next message to be sent to the calling process.Notice that chunked encoding can add headers so that there are more headers in the
stream_endmessage than instream_start. When streaming to a file and the request is asynchronous, the message{http, {RequestId, saved_to_file}}is sent.Default is
none.body_format- Defines if the body is to be delivered as a string or binary. This option is only valid for the synchronous request.Default is
string.full_result- Defines if a "full result" is to be returned to the caller (that is, the body, the headers, and the entire status line) or not (the body and the status code).Default is
true.headers_as_is- Defines if the headers provided by the user are to be made lower case or to be regarded as case sensitive.The HTTP standard requires them to be case insensitive. Use this feature only if there is no other way to communicate with the server or for testing purpose. When this option is used, no headers are automatically added. All necessary headers must be provided by the user.
Default is
false.socket_opts- Socket options to be used for this request.See the options used by
gen_tcpandsslOverrides any value set by function set_options.
The validity of the options is not checked by the HTTP client they are assumed to be correct and passed on to ssl application and inet driver, which may reject them if they are not correct.
Note
Persistent connections are not supported when setting the
socket_optsoption. Whensocket_optsis not set the current implementation assumes the requests to the same host, port combination will use the same socket options.By default the socket options set by function set_options/1,2 are used when establishing a connection.
receiver- Defines how the client delivers the result of an asynchronous request (synchas the valuefalse).pid/0- Messages are sent to this process in the format{http, ReplyInfo}.function/1- Information is delivered to the receiver through calls to the provided funReceiver(ReplyInfo).{Module, Function, Args}- Information is delivered to the receiver through calls to the callback functionapply(Module, Function, [ReplyInfo | Args]).
In all of these cases,
ReplyInfohas the following structure:{RequestId, saved_to_file} {RequestId, {error, Reason}} {RequestId, Result} {RequestId, stream_start, Headers} {RequestId, stream_start, Headers, HandlerPid} {RequestId, stream, BinBodyPart} {RequestId, stream_end, Headers}Default is the
pidof the process calling the request function (self/0).ipv6_host_with_brackets- Defines when parsing the Host-Port part of an URI with an IPv6 address with brackets, if those brackets are to be retained (true) or stripped (false).Default is
false.
-spec reset_cookies() -> Void when Void :: term().
Equivalent to reset_cookies/1.
Resets (clears) the cookie database for the specified Profile. If no profile
is specified the default profile is used.
-spec set_options(Options) -> ok | {error, Reason} when Options :: [Option], Option :: {proxy, {Proxy, NoProxy}} | {https_proxy, {Proxy, NoProxy}} | {max_sessions, MaxSessions} | {max_keep_alive_length, MaxKeepAlive} | {keep_alive_timeout, KeepAliveTimeout} | {max_pipeline_length, MaxPipeline} | {pipeline_timeout, PipelineTimeout} | {cookies, CookieMode} | {ipfamily, IpFamily} | {ip, IpAddress} | {port, Port} | {socket_opts, SocketOpts} | {verbose, VerboseMode} | {unix_socket, UnixSocket}, Proxy :: {HostName, Port}, Port :: non_neg_integer(), NoProxy :: [DomainDesc | HostName | IpAddressDesc], MaxSessions :: integer(), MaxKeepAlive :: integer(), KeepAliveTimeout :: integer(), MaxPipeline :: integer(), PipelineTimeout :: integer(), CookieMode :: enabled | disabled | verify, IpFamily :: inet | inet6 | local | inet6fb4, IpAddressDesc :: uri_string:uri_string(), IpAddress :: inet:ip_address(), VerboseMode :: false | verbose | debug | trace, SocketOpts :: [SocketOpt], SocketOpt :: term(), UnixSocket :: file:name_all(), Reason :: term(), DomainDesc :: string(), HostName :: uri_string:uri_string().
Equivalent to set_options/2.
-spec set_options(Options, Profile) -> ok | {error, Reason} when Options :: [Option], Option :: {proxy, {Proxy, NoProxy}} | {https_proxy, {Proxy, NoProxy}} | {max_sessions, MaxSessions} | {max_keep_alive_length, MaxKeepAlive} | {keep_alive_timeout, KeepAliveTimeout} | {max_pipeline_length, MaxPipeline} | {pipeline_timeout, PipelineTimeout} | {cookies, CookieMode} | {ipfamily, IpFamily} | {ip, IpAddress} | {port, Port} | {socket_opts, [SocketOpt]} | {verbose, VerboseMode} | {unix_socket, UnixSocket}, Profile :: atom() | pid(), SocketOpt :: term(), Proxy :: {HostName, Port}, Port :: non_neg_integer(), NoProxy :: [DomainDesc | HostName | IpAddressDesc], MaxSessions :: integer(), MaxKeepAlive :: integer(), KeepAliveTimeout :: integer(), MaxPipeline :: integer(), PipelineTimeout :: integer(), CookieMode :: enabled | disabled | verify, IpFamily :: inet | inet6 | local | inet6fb4, IpAddressDesc :: uri_string:uri_string(), IpAddress :: inet:ip_address(), VerboseMode :: false | verbose | debug | trace, UnixSocket :: string(), Reason :: term(), DomainDesc :: string(), HostName :: uri_string:uri_string().
Sets options to be used for subsequent requests.
HostName- Example: "localhost" or "foo.bar.se"DomainDesc- Example"*.Domain"or"*.ericsson.se"IpAddressDesc- Example: "134.138" or "[FEDC:BA98" (all IP addresses starting with 134.138 or FEDC:BA98), "66.35.250.150" or "[2010:836B:4179::836B:4179]" (a complete IP address).proxydefaults to{undefined, []}, that is, no proxy is configured andhttps_proxydefaults to the value ofproxy.MaxSessions-MaxSessionsMaximum number of persistent connections to a host. Default is2.MaxKeepAlive-MaxKeepAliveMaximum number of outstanding requests on the same connection to a host. Default is5.KeepAliveTimeout-KeepAliveTimeoutIf a persistent connection is idle longer than thekeep_alive_timeoutin milliseconds, the client closes the connection. The server can also have such a time-out but do not take that for granted. Default is120000(= 2 min).MaxPipeline-MaxPipelineMaximum number of outstanding requests on a pipelined connection to a host. Default is2.PipelineTimeout-PipelineTimeoutIf a persistent connection is idle longer than thepipeline_timeoutin milliseconds, the client closes the connection. Default is0, which results in pipelining not being used.CookieMode- If cookies are enabled, all valid cookies are automatically saved in the cookie database of the client manager. If optionverifyis used, functionstore_cookies/2has to be called for the cookies to be saved. Default isdisabled.IpFamily- Default isinet. Withinet6fb4option, IPv6 will be preferred but if connection fails, an IPv4 fallback connection attempt will be made.IpAddress- If the host has several network interfaces, this option specifies which one to use. See gen_tcp:connect/3,4 for details.Port- Example:8080. Local port number to use. See gen_tcp:connect/3,4 for details.SocketOpts- The options are appended to the socket options used by the client. These are the default values when a new request handler is started (for the initial connect). They are passed directly to the underlying transport (gen_tcporSSL) without verification.VerboseMode- Default isfalse. This option is used to switch on (or off) different levels of Erlang trace on the client. It is a debug feature.Profile- When startedstand_aloneonly the pid can be used.UnixSocket- Experimental option for sending HTTP requests over a unix domain socket. The value ofunix_socketshall be the full path to a unix domain socket file with read/write permissions for the erlang process. Default isundefined.
Note
If possible, the client keeps its connections alive and uses persistent connections with or without pipeline depending on configuration and current circumstances. The HTTP/1.1 specification does not provide a guideline for how many requests that are ideal to be sent on a persistent connection. This depends much on the application.
A long queue of requests can cause a user-perceived delay, as earlier requests can take a long time to complete. The HTTP/1.1 specification suggests a limit of two persistent connections per server, which is the default value of option
max_sessions.The current implementation assumes the requests to the same host, port combination will use the same socket options.
Returns ssl options which can be used to verify the host, uses
public_key:cacerts_get() to read CA certicates
and if WildcardHostName is true adds the hostname check from
public_key:public_key:pkix_verify_hostname_match_fun(https)
to the options.
-spec store_cookies(SetCookieHeaders, Url) -> ok | {error, Reason} when SetCookieHeaders :: [HttpHeader], HttpHeader :: {Field :: [byte()], Value :: binary() | iolist()}, Url :: term(), Reason :: term().
Equivalent to store_cookies/3.
-spec store_cookies(SetCookieHeaders, Url, Profile) -> ok | {error, Reason} when SetCookieHeaders :: [HttpHeader], HttpHeader :: {Field :: [byte()], Value :: binary() | iolist()}, Url :: term(), Profile :: atom() | pid(), Reason :: term().
Saves the cookies defined in SetCookieHeaders in the client profile cookie
database. Call this function if option cookies is set to verify. If no
profile is specified, the default profile is used.
-spec stream_next(Pid) -> ok when Pid :: pid().
Triggers the next message to be streamed, that is, the same behavior as active ones for sockets.
-spec which_cookies() -> [CookieStores] when CookieStores :: {cookies, Cookies} | {session_cookies, Cookies}, Cookies :: [term()].
Equivalent to which_cookies/1.
-spec which_cookies(Profile) -> [CookieStores] when Profile :: atom() | pid(), CookieStores :: {cookies, Cookies} | {session_cookies, Cookies}, Cookies :: [term()].
Produces a list of the entire cookie database. Intended for debugging/testing purposes. If no profile is specified, the default profile is used.
-spec which_sessions() -> SessionInfo when SessionInfo :: {GoodSession, BadSessions, NonSessions}, GoodSession :: [Session], BadSessions :: [term()], NonSessions :: [term()], Session :: term().
Equivalent to which_sessions/1.
-spec which_sessions(Profile) -> SessionInfo when Profile :: atom() | pid(), SessionInfo :: {GoodSession, BadSessions, NonSessions}, GoodSession :: [Session], BadSessions :: [term()], NonSessions :: [term()], Session :: term().
This function is intended for debugging only. It produces a slightly processed dump of the session database. The first list of the session information tuple will contain session information on an internal format. The last two lists of the session information tuple should always be empty if the code is working as intended. If no profile is specified, the default profile is used.