| 1 |
NAME |
| 2 |
AnyEvent::HTTP - simple but non-blocking HTTP/HTTPS client |
| 3 |
|
| 4 |
SYNOPSIS |
| 5 |
use AnyEvent::HTTP; |
| 6 |
|
| 7 |
http_get "http://www.nethype.de/", sub { print $_[1] }; |
| 8 |
|
| 9 |
# ... do something else here |
| 10 |
|
| 11 |
DESCRIPTION |
| 12 |
This module is an AnyEvent user, you need to make sure that you use and |
| 13 |
run a supported event loop. |
| 14 |
|
| 15 |
This module implements a simple, stateless and non-blocking HTTP client. |
| 16 |
It supports GET, POST and other request methods, cookies and more, all |
| 17 |
on a very low level. It can follow redirects supports proxies and |
| 18 |
automatically limits the number of connections to the values specified |
| 19 |
in the RFC. |
| 20 |
|
| 21 |
It should generally be a "good client" that is enough for most HTTP |
| 22 |
tasks. Simple tasks should be simple, but complex tasks should still be |
| 23 |
possible as the user retains control over request and response headers. |
| 24 |
|
| 25 |
The caller is responsible for authentication management, cookies (if the |
| 26 |
simplistic implementation in this module doesn't suffice), referer and |
| 27 |
other high-level protocol details for which this module offers only |
| 28 |
limited support. |
| 29 |
|
| 30 |
METHODS |
| 31 |
http_get $url, key => value..., $cb->($data, $headers) |
| 32 |
Executes an HTTP-GET request. See the http_request function for |
| 33 |
details on additional parameters and the return value. |
| 34 |
|
| 35 |
http_head $url, key => value..., $cb->($data, $headers) |
| 36 |
Executes an HTTP-HEAD request. See the http_request function for |
| 37 |
details on additional parameters and the return value. |
| 38 |
|
| 39 |
http_post $url, $body, key => value..., $cb->($data, $headers) |
| 40 |
Executes an HTTP-POST request with a request body of $body. See the |
| 41 |
http_request function for details on additional parameters and the |
| 42 |
return value. |
| 43 |
|
| 44 |
http_request $method => $url, key => value..., $cb->($data, $headers) |
| 45 |
Executes a HTTP request of type $method (e.g. "GET", "POST"). The |
| 46 |
URL must be an absolute http or https URL. |
| 47 |
|
| 48 |
When called in void context, nothing is returned. In other contexts, |
| 49 |
"http_request" returns a "cancellation guard" - you have to keep the |
| 50 |
object at least alive until the callback get called. If the object |
| 51 |
gets destroyed before the callback is called, the request will be |
| 52 |
cancelled. |
| 53 |
|
| 54 |
The callback will be called with the response body data as first |
| 55 |
argument (or "undef" if an error occured), and a hash-ref with |
| 56 |
response headers as second argument. |
| 57 |
|
| 58 |
All the headers in that hash are lowercased. In addition to the |
| 59 |
response headers, the "pseudo-headers" (uppercase to avoid clashing |
| 60 |
with possible response headers) "HTTPVersion", "Status" and "Reason" |
| 61 |
contain the three parts of the HTTP Status-Line of the same name. If |
| 62 |
an error occurs during the body phase of a request, then the |
| 63 |
original "Status" and "Reason" values from the header are available |
| 64 |
as "OrigStatus" and "OrigReason". |
| 65 |
|
| 66 |
The pseudo-header "URL" contains the actual URL (which can differ |
| 67 |
from the requested URL when following redirects - for example, you |
| 68 |
might get an error that your URL scheme is not supported even though |
| 69 |
your URL is a valid http URL because it redirected to an ftp URL, in |
| 70 |
which case you can look at the URL pseudo header). |
| 71 |
|
| 72 |
The pseudo-header "Redirect" only exists when the request was a |
| 73 |
result of an internal redirect. In that case it is an array |
| 74 |
reference with the "($data, $headers)" from the redirect response. |
| 75 |
Note that this response could in turn be the result of a redirect |
| 76 |
itself, and "$headers->{Redirect}[1]{Redirect}" will then contain |
| 77 |
the original response, and so on. |
| 78 |
|
| 79 |
If the server sends a header multiple times, then their contents |
| 80 |
will be joined together with a comma (","), as per the HTTP spec. |
| 81 |
|
| 82 |
If an internal error occurs, such as not being able to resolve a |
| 83 |
hostname, then $data will be "undef", "$headers->{Status}" will be |
| 84 |
"59x" (usually 599) and the "Reason" pseudo-header will contain an |
| 85 |
error message. |
| 86 |
|
| 87 |
A typical callback might look like this: |
| 88 |
|
| 89 |
sub { |
| 90 |
my ($body, $hdr) = @_; |
| 91 |
|
| 92 |
if ($hdr->{Status} =~ /^2/) { |
| 93 |
... everything should be ok |
| 94 |
} else { |
| 95 |
print "error, $hdr->{Status} $hdr->{Reason}\n"; |
| 96 |
} |
| 97 |
} |
| 98 |
|
| 99 |
Additional parameters are key-value pairs, and are fully optional. |
| 100 |
They include: |
| 101 |
|
| 102 |
recurse => $count (default: $MAX_RECURSE) |
| 103 |
Whether to recurse requests or not, e.g. on redirects, |
| 104 |
authentication retries and so on, and how often to do so. |
| 105 |
|
| 106 |
headers => hashref |
| 107 |
The request headers to use. Currently, "http_request" may |
| 108 |
provide its own "Host:", "Content-Length:", "Connection:" and |
| 109 |
"Cookie:" headers and will provide defaults for "User-Agent:" |
| 110 |
and "Referer:" (this can be suppressed by using "undef" for |
| 111 |
these headers in which case they won't be sent at all). |
| 112 |
|
| 113 |
timeout => $seconds |
| 114 |
The time-out to use for various stages - each connect attempt |
| 115 |
will reset the timeout, as will read or write activity, i.e. |
| 116 |
this is not an overall timeout. |
| 117 |
|
| 118 |
Default timeout is 5 minutes. |
| 119 |
|
| 120 |
proxy => [$host, $port[, $scheme]] or undef |
| 121 |
Use the given http proxy for all requests. If not specified, |
| 122 |
then the default proxy (as specified by $ENV{http_proxy}) is |
| 123 |
used. |
| 124 |
|
| 125 |
$scheme must be either missing, "http" for HTTP or "https" for |
| 126 |
HTTPS. |
| 127 |
|
| 128 |
body => $string |
| 129 |
The request body, usually empty. Will be-sent as-is (future |
| 130 |
versions of this module might offer more options). |
| 131 |
|
| 132 |
cookie_jar => $hash_ref |
| 133 |
Passing this parameter enables (simplified) cookie-processing, |
| 134 |
loosely based on the original netscape specification. |
| 135 |
|
| 136 |
The $hash_ref must be an (initially empty) hash reference which |
| 137 |
will get updated automatically. It is possible to save the |
| 138 |
cookie_jar to persistent storage with something like JSON or |
| 139 |
Storable, but this is not recommended, as expiry times are |
| 140 |
currently being ignored. |
| 141 |
|
| 142 |
Note that this cookie implementation is not of very high |
| 143 |
quality, nor meant to be complete. If you want complete cookie |
| 144 |
management you have to do that on your own. "cookie_jar" is |
| 145 |
meant as a quick fix to get some cookie-using sites working. |
| 146 |
Cookies are a privacy disaster, do not use them unless required |
| 147 |
to. |
| 148 |
|
| 149 |
tls_ctx => $scheme | $tls_ctx |
| 150 |
Specifies the AnyEvent::TLS context to be used for https |
| 151 |
connections. This parameter follows the same rules as the |
| 152 |
"tls_ctx" parameter to AnyEvent::Handle, but additionally, the |
| 153 |
two strings "low" or "high" can be specified, which give you a |
| 154 |
predefined low-security (no verification, highest compatibility) |
| 155 |
and high-security (CA and common-name verification) TLS context. |
| 156 |
|
| 157 |
The default for this option is "low", which could be interpreted |
| 158 |
as "give me the page, no matter what". |
| 159 |
|
| 160 |
on_prepare => $callback->($fh) |
| 161 |
In rare cases you need to "tune" the socket before it is used to |
| 162 |
connect (for exmaple, to bind it on a given IP address). This |
| 163 |
parameter overrides the prepare callback passed to |
| 164 |
"AnyEvent::Socket::tcp_connect" and behaves exactly the same way |
| 165 |
(e.g. it has to provide a timeout). See the description for the |
| 166 |
$prepare_cb argument of "AnyEvent::Socket::tcp_connect" for |
| 167 |
details. |
| 168 |
|
| 169 |
tcp_connect => $callback->($host, $service, $connect_cb, |
| 170 |
$prepare_cb) |
| 171 |
In even rarer cases you want total control over how |
| 172 |
AnyEvent::HTTP establishes connections. Normally it uses |
| 173 |
AnyEvent::Socket::tcp_connect to do this, but you can provide |
| 174 |
your own "tcp_connect" function - obviously, it has to follow |
| 175 |
the same calling conventions, except that it may always return a |
| 176 |
connection guard object. |
| 177 |
|
| 178 |
There are probably lots of weird uses for this function, |
| 179 |
starting from tracing the hosts "http_request" actually tries to |
| 180 |
connect, to (inexact but fast) host => IP address caching or |
| 181 |
even socks protocol support. |
| 182 |
|
| 183 |
on_header => $callback->($headers) |
| 184 |
When specified, this callback will be called with the header |
| 185 |
hash as soon as headers have been successfully received from the |
| 186 |
remote server (not on locally-generated errors). |
| 187 |
|
| 188 |
It has to return either true (in which case AnyEvent::HTTP will |
| 189 |
continue), or false, in which case AnyEvent::HTTP will cancel |
| 190 |
the download (and call the finish callback with an error code of |
| 191 |
598). |
| 192 |
|
| 193 |
This callback is useful, among other things, to quickly reject |
| 194 |
unwanted content, which, if it is supposed to be rare, can be |
| 195 |
faster than first doing a "HEAD" request. |
| 196 |
|
| 197 |
Example: cancel the request unless the content-type is |
| 198 |
"text/html". |
| 199 |
|
| 200 |
on_header => sub { |
| 201 |
$_[0]{"content-type"} =~ /^text\/html\s*(?:;|$)/ |
| 202 |
}, |
| 203 |
|
| 204 |
on_body => $callback->($partial_body, $headers) |
| 205 |
When specified, all body data will be passed to this callback |
| 206 |
instead of to the completion callback. The completion callback |
| 207 |
will get the empty string instead of the body data. |
| 208 |
|
| 209 |
It has to return either true (in which case AnyEvent::HTTP will |
| 210 |
continue), or false, in which case AnyEvent::HTTP will cancel |
| 211 |
the download (and call the completion callback with an error |
| 212 |
code of 598). |
| 213 |
|
| 214 |
This callback is useful when the data is too large to be held in |
| 215 |
memory (so the callback writes it to a file) or when only some |
| 216 |
information should be extracted, or when the body should be |
| 217 |
processed incrementally. |
| 218 |
|
| 219 |
It is usually preferred over doing your own body handling via |
| 220 |
"want_body_handle", but in case of streaming APIs, where HTTP is |
| 221 |
only used to create a connection, "want_body_handle" is the |
| 222 |
better alternative, as it allows you to install your own event |
| 223 |
handler, reducing resource usage. |
| 224 |
|
| 225 |
want_body_handle => $enable |
| 226 |
When enabled (default is disabled), the behaviour of |
| 227 |
AnyEvent::HTTP changes considerably: after parsing the headers, |
| 228 |
and instead of downloading the body (if any), the completion |
| 229 |
callback will be called. Instead of the $body argument |
| 230 |
containing the body data, the callback will receive the |
| 231 |
AnyEvent::Handle object associated with the connection. In error |
| 232 |
cases, "undef" will be passed. When there is no body (e.g. |
| 233 |
status 304), the empty string will be passed. |
| 234 |
|
| 235 |
The handle object might or might not be in TLS mode, might be |
| 236 |
connected to a proxy, be a persistent connection etc., and |
| 237 |
configured in unspecified ways. The user is responsible for this |
| 238 |
handle (it will not be used by this module anymore). |
| 239 |
|
| 240 |
This is useful with some push-type services, where, after the |
| 241 |
initial headers, an interactive protocol is used (typical |
| 242 |
example would be the push-style twitter API which starts a |
| 243 |
JSON/XML stream). |
| 244 |
|
| 245 |
If you think you need this, first have a look at "on_body", to |
| 246 |
see if that doesn't solve your problem in a better way. |
| 247 |
|
| 248 |
Example: make a simple HTTP GET request for http://www.nethype.de/ |
| 249 |
|
| 250 |
http_request GET => "http://www.nethype.de/", sub { |
| 251 |
my ($body, $hdr) = @_; |
| 252 |
print "$body\n"; |
| 253 |
}; |
| 254 |
|
| 255 |
Example: make a HTTP HEAD request on https://www.google.com/, use a |
| 256 |
timeout of 30 seconds. |
| 257 |
|
| 258 |
http_request |
| 259 |
GET => "https://www.google.com", |
| 260 |
timeout => 30, |
| 261 |
sub { |
| 262 |
my ($body, $hdr) = @_; |
| 263 |
use Data::Dumper; |
| 264 |
print Dumper $hdr; |
| 265 |
} |
| 266 |
; |
| 267 |
|
| 268 |
Example: make another simple HTTP GET request, but immediately try |
| 269 |
to cancel it. |
| 270 |
|
| 271 |
my $request = http_request GET => "http://www.nethype.de/", sub { |
| 272 |
my ($body, $hdr) = @_; |
| 273 |
print "$body\n"; |
| 274 |
}; |
| 275 |
|
| 276 |
undef $request; |
| 277 |
|
| 278 |
DNS CACHING |
| 279 |
AnyEvent::HTTP uses the AnyEvent::Socket::tcp_connect function for the |
| 280 |
actual connection, which in turn uses AnyEvent::DNS to resolve |
| 281 |
hostnames. The latter is a simple stub resolver and does no caching on |
| 282 |
its own. If you want DNS caching, you currently have to provide your own |
| 283 |
default resolver (by storing a suitable resolver object in |
| 284 |
$AnyEvent::DNS::RESOLVER). |
| 285 |
|
| 286 |
GLOBAL FUNCTIONS AND VARIABLES |
| 287 |
AnyEvent::HTTP::set_proxy "proxy-url" |
| 288 |
Sets the default proxy server to use. The proxy-url must begin with |
| 289 |
a string of the form "http://host:port" (optionally "https:..."), |
| 290 |
croaks otherwise. |
| 291 |
|
| 292 |
To clear an already-set proxy, use "undef". |
| 293 |
|
| 294 |
$date = AnyEvent::HTTP::format_date $timestamp |
| 295 |
Takes a POSIX timestamp (seconds since the epoch) and formats it as |
| 296 |
a HTTP Date (RFC 2616). |
| 297 |
|
| 298 |
$timestamp = AnyEvent::HTTP::parse_date $date |
| 299 |
Takes a HTTP Date (RFC 2616) and returns the corresponding POSIX |
| 300 |
timestamp, or "undef" if the date cannot be parsed. |
| 301 |
|
| 302 |
$AnyEvent::HTTP::MAX_RECURSE |
| 303 |
The default value for the "recurse" request parameter (default: 10). |
| 304 |
|
| 305 |
$AnyEvent::HTTP::USERAGENT |
| 306 |
The default value for the "User-Agent" header (the default is |
| 307 |
"Mozilla/5.0 (compatible; U; AnyEvent-HTTP/$VERSION; |
| 308 |
+http://software.schmorp.de/pkg/AnyEvent)"). |
| 309 |
|
| 310 |
$AnyEvent::HTTP::MAX_PER_HOST |
| 311 |
The maximum number of concurrent connections to the same host |
| 312 |
(identified by the hostname). If the limit is exceeded, then the |
| 313 |
additional requests are queued until previous connections are |
| 314 |
closed. |
| 315 |
|
| 316 |
The default value for this is 4, and it is highly advisable to not |
| 317 |
increase it. |
| 318 |
|
| 319 |
$AnyEvent::HTTP::ACTIVE |
| 320 |
The number of active connections. This is not the number of |
| 321 |
currently running requests, but the number of currently open and |
| 322 |
non-idle TCP connections. This number of can be useful for |
| 323 |
load-leveling. |
| 324 |
|
| 325 |
SOCKS PROXIES |
| 326 |
Socks proxies are not directly supported by AnyEvent::HTTP. You can |
| 327 |
compile your perl to support socks, or use an external program such as |
| 328 |
socksify (dante) or tsocks to make your program use a socks proxy |
| 329 |
transparently. |
| 330 |
|
| 331 |
Alternatively, for AnyEvent::HTTP only, you can use your own |
| 332 |
"tcp_connect" function that does the proxy handshake - here is an |
| 333 |
example that works with socks4a proxies: |
| 334 |
|
| 335 |
use Errno; |
| 336 |
use AnyEvent::Util; |
| 337 |
use AnyEvent::Socket; |
| 338 |
use AnyEvent::Handle; |
| 339 |
|
| 340 |
# host, port and username of/for your socks4a proxy |
| 341 |
my $socks_host = "10.0.0.23"; |
| 342 |
my $socks_port = 9050; |
| 343 |
my $socks_user = ""; |
| 344 |
|
| 345 |
sub socks4a_connect { |
| 346 |
my ($host, $port, $connect_cb, $prepare_cb) = @_; |
| 347 |
|
| 348 |
my $hdl = new AnyEvent::Handle |
| 349 |
connect => [$socks_host, $socks_port], |
| 350 |
on_prepare => sub { $prepare_cb->($_[0]{fh}) }, |
| 351 |
on_error => sub { $connect_cb->() }, |
| 352 |
; |
| 353 |
|
| 354 |
$hdl->push_write (pack "CCnNZ*Z*", 4, 1, $port, 1, $socks_user, $host); |
| 355 |
|
| 356 |
$hdl->push_read (chunk => 8, sub { |
| 357 |
my ($hdl, $chunk) = @_; |
| 358 |
my ($status, $port, $ipn) = unpack "xCna4", $chunk; |
| 359 |
|
| 360 |
if ($status == 0x5a) { |
| 361 |
$connect_cb->($hdl->{fh}, (format_address $ipn) . ":$port"); |
| 362 |
} else { |
| 363 |
$! = Errno::ENXIO; $connect_cb->(); |
| 364 |
} |
| 365 |
}); |
| 366 |
|
| 367 |
$hdl |
| 368 |
} |
| 369 |
|
| 370 |
Use "socks4a_connect" instead of "tcp_connect" when doing |
| 371 |
"http_request"s, possibly after switching off other proxy types: |
| 372 |
|
| 373 |
AnyEvent::HTTP::set_proxy undef; # usually you do not want other proxies |
| 374 |
|
| 375 |
http_get 'http://www.google.com', tcp_connect => \&socks4a_connect, sub { |
| 376 |
my ($data, $headers) = @_; |
| 377 |
... |
| 378 |
}; |
| 379 |
|
| 380 |
SEE ALSO |
| 381 |
AnyEvent. |
| 382 |
|
| 383 |
AUTHOR |
| 384 |
Marc Lehmann <schmorp@schmorp.de> |
| 385 |
http://home.schmorp.de/ |
| 386 |
|
| 387 |
With many thanks to Дмитрий Шалашов, who provided |
| 388 |
countless testcases and bugreports. |
| 389 |
|
