forked from aws/aws-sdk-ruby
-
Notifications
You must be signed in to change notification settings - Fork 0
/
presigned_post.rb
554 lines (499 loc) · 18.3 KB
/
presigned_post.rb
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
# Copyright 2011-2013 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"). You
# may not use this file except in compliance with the License. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
# ANY KIND, either express or implied. See the License for the specific
# language governing permissions and limitations under the License.
require 'uri'
require 'time'
module AWS
class S3
# Helper to generate form fields for presigned POST requests to
# a bucket. You can use this to create a form that can be used
# from a web browser to upload objects to S3 while specifying
# conditions on what can be uploaded and how it is processed and
# stored.
#
# @example Form fields for uploading by file name
#
# form = bucket.presigned_post(:key => "photos/${filename}")
# form.url.to_s # => "https://mybucket.s3.amazonaws.com/"
# form.fields # => { "AWSAccessKeyId" => "...", ... }
#
# @example Generating a minimal HTML form
#
# form = bucket.objects.myobj.presigned_post
# hidden_inputs = form.fields.map do |(name, value)|
# %(<input type="hidden" name="#{name}" value="#{value}" />)
# end
# <<-END
# <form action="#{form.url}" method="post" enctype="multipart/form-data">
# #{hidden_inputs}
# <input type="file" name="file" />
# </form>
# END
#
# @example Restricting the size of the uploaded object
#
# bucket.presigned_post(:content_length => 1..(10*1024))
#
# @example Restricting the key prefix
#
# bucket.presigned_post.where(:key).starts_with("photos/")
#
class PresignedPost
include Core::Model
# @return [Bucket] The bucket to which data can be uploaded
# using the form fields
attr_reader :bucket
# @return [String] The key of the object that will be
# uploaded. If this is nil, then the object can be uploaded
# with any key that satisfies the conditions specified for
# the upload (see {#where}).
attr_reader :key
# @return [Hash] A hash of the metadata fields included in the
# signed fields. Additional metadata fields may be provided
# with the upload as long as they satisfy the conditions
# specified for the upload (see {#where}).
attr_reader :metadata
# @return [Range] The range of acceptable object sizes for the
# upload. By default any size object may be uploaded.
attr_reader :content_length
# @api private
attr_reader :conditions
# @return [Array<String>] Additional fields which may be sent
# with the upload. These will be included in the policy so
# that they can be sent with any value. S3 will ignore
# them.
attr_reader :ignored_fields
# @return The expiration time for the signature. By default
# the signature will expire an hour after it is generated.
attr_reader :expires
# @api private
SPECIAL_FIELDS = [:key,
:policy,
:signature,
:expires,
:metadata,
:content_length,
:conditions,
:ignore,
:secure]
# Creates a new presigned post object.
#
# @param [Bucket] bucket The bucket to which data can be uploaded
# using the form fields.
#
# @param [Hash] opts Additional options for the upload. Aside
# from `:secure`, `:expires`, `:content_length` and `:ignore`
# the values provided here will be stored in the hash returned
# from the {#fields} method, and the policy in that hash will
# restrict their values to the values provided. If you
# instead want to only restrict the values and not provide
# them -- for example, if your application generates separate
# form fields for those values -- you should use the {#where}
# method on the returned object instead of providing the
# values here.
#
# @option opts [String] :key The key of the object that will
# be uploaded. If this is nil, then the object can be
# uploaded with any key that satisfies the conditions
# specified for the upload (see {#where}).
#
# @option opts [Boolean] :secure By setting this to false, you
# can cause {#url} to return an HTTP URL. By default it
# returns an HTTPS URL.
#
# @option opts [Time, DateTime, Integer, String] :expires The
# time at which the signature will expire. By default the
# signature will expire one hour after it is generated
# (e.g. when {#fields} is called).
#
# When the value is a Time or DateTime, the signature
# expires at the specified time. When it is an integer, the
# signature expires the specified number of seconds after it
# is generated. When it is a string, the string is parsed
# as a time (using Time.parse) and the signature expires at
# that time.
#
# @option opts [String] :cache_control Sets the Cache-Control
# header stored with the object.
#
# @option opts [String] :content_type Sets the Content-Type
# header stored with the object.
#
# @option opts [String] :content_disposition Sets the
# Content-Disposition header stored with the object.
#
# @option opts [String] :expires_header Sets the Expires
# header stored with the object.
#
# @option options [Symbol] :acl A canned access control
# policy. Valid values are:
# * `:private`
# * `:public_read`
# * `:public_read_write`
# * `:authenticated_read`
# * `:bucket_owner_read`
# * `:bucket_owner_full_control`
#
# @option options [Symbol] :server_side_encryption (nil) If this
# option is set, the object will be stored using server side
# encryption. The only valid value is `:aes256`, which
# specifies that the object should be stored using the AES
# encryption algorithm with 256 bit keys. By default, this
# option uses the value of the `:s3_server_side_encryption`
# option in the current configuration; for more information,
# see {AWS.config}.
#
# @option opts [String] :success_action_redirect The URL to
# which the client is redirected upon successful upload.
#
# @option opts [Integer] :success_action_status The status
# code returned to the client upon successful upload if
# `:success_action_redirect` is not specified. Accepts the
# values 200, 201, or 204 (default).
#
# If the value is set to 200 or 204, Amazon S3 returns an
# empty document with a 200 or 204 status code.
#
# If the value is set to 201, Amazon S3 returns an XML
# document with a 201 status code. For information on the
# content of the XML document, see
# [POST Object](http://docs.aws.amazon.com/AmazonS3/2006-03-01/API/index.html?RESTObjectPOST.html).
#
# @option opts [Hash] :metadata A hash of the metadata fields
# included in the signed fields. Additional metadata fields
# may be provided with the upload as long as they satisfy
# the conditions specified for the upload (see {#where}).
#
# @option opts [Integer, Range] :content_length The range of
# acceptable object sizes for the upload. By default any
# size object may be uploaded.
#
# @option opts [Array<String>] :ignore Additional fields which
# may be sent with the upload. These will be included in
# the policy so that they can be sent with any value. S3
# will ignore them.
def initialize(bucket, opts = {})
@bucket = bucket
@key = opts[:key]
@secure = (opts[:secure] != false)
@fields = {}
# TODO normalize all values to @fields
opts.each do |opt_key, opt_val|
@fields[opt_key] = opt_val unless SPECIAL_FIELDS.include? opt_key
end
@metadata = opts[:metadata] || {}
@content_length = range_value(opts[:content_length])
@conditions = opts[:conditions] || {}
@ignored_fields = [opts[:ignore]].flatten.compact
@expires = opts[:expires] || Time.now.utc + 60*60
super
@fields[:server_side_encryption] =
config.s3_server_side_encryption unless
@fields.key?(:server_side_encryption)
@fields.delete(:server_side_encryption) if
@fields[:server_side_encryption].nil?
end
# @return [Boolean] True if {#url} generates an HTTPS url.
def secure?
@secure
end
# @return [URI::HTTP, URI::HTTPS] The URL to which the form
# fields should be POSTed. If you are using the fields in
# an HTML form, this is the URL to put in the `action`
# attribute of the form tag.
def url
req = Request.new
req.bucket = bucket.name
req.host = config.s3_endpoint
build_uri(req)
end
# Lets you specify conditions on a field. See
# {PresignedPost#where} for usage examples.
class ConditionBuilder
# @api private
def initialize(post, field)
@post = post
@field = field
end
# Specifies that the value of the field must equal the
# provided value.
def is(value)
if @field == :content_length
self.in(value)
else
@post.with_equality_condition(@field, value)
end
end
# Specifies that the value of the field must begin with the
# provided value. If you are specifying a condition on the
# "key" field, note that this check takes place after the
# `${filename}` variable is expanded. This is only valid
# for the following fields:
#
# * `:key`
# * `:cache_control`
# * `:content_type`
# * `:content_disposition`
# * `:content_encoding`
# * `:expires_header`
# * `:acl`
# * `:success_action_redirect`
# * metadata fields (see {#where_metadata})
def starts_with(prefix)
@post.with_prefix_condition(@field, prefix)
end
# Specifies that the value of the field must be in the given
# range. This may only be used to constrain the
# `:content_length` field,
# e.g. `presigned_post.with(:conent_length).in(1..4)`.
def in(range)
@post.refine(:content_length => range)
end
end
# Adds a condition to the policy for the POST. Use
# {#where_metadata} to add metadata conditions.
#
# @example Restricting the ACL to "bucket-owner" ACLs
# presigned_post.where(:acl).starts_with("bucket-owner")
#
# @param [Symbol] field The field for which a condition should
# be added. In addition to any arbitrary values you have set,
# the following values are also permitted:
#
# * `:key`
# * `:content_length`
# * `:cache_control`
# * `:content_type`
# * `:content_disposition`
# * `:content_encoding`
# * `:expires_header`
# * `:acl`
# * `:success_action_redirect`
# * `:success_action_status`
#
# @return [ConditionBuilder] An object that allows you to
# specify a condition on the field.
def where(field)
ConditionBuilder.new(self, field)
end
# Adds a condition to the policy for the POST to constrain the
# values of metadata fields uploaded with the object. If a
# metadata field does not have a condition associated with it
# and is not specified in the constructor (see {#metadata})
# then S3 will reject it.
#
# @param [Symbol, String] field The name of the metadata
# attribute. For example, `:color` corresponds to the
# "x-amz-meta-color" field in the POST body.
#
# @return [ConditionBuilder] An object that allows you to
# specify a condition on the metadata attribute.
def where_metadata(field)
where("x-amz-meta-#{field}")
end
# @return [String] The Base64-encoded JSON policy document.
def policy
json = {
"expiration" => format_expiration,
"conditions" => generate_conditions
}.to_json
Base64.encode64(json).tr("\n","")
end
# @return [Hash] A collection of form fields (including a
# signature and a policy) that can be used to POST data to
# S3. Additional form fields may be added after the fact as
# long as they are described by a policy condition (see
# {#where}).
def fields
secret = config.credential_provider.secret_access_key
signature = Core::Signers::Base.sign(secret, policy, 'sha1')
fields = {
"AWSAccessKeyId" => config.credential_provider.access_key_id,
"key" => key,
"policy" => policy,
"signature" => signature
}.merge(optional_fields)
if token = config.credential_provider.session_token
fields["x-amz-security-token"] = token
end
fields.merge(optional_fields)
end
# @api private
def with_equality_condition(option_name, value)
field_name = field_name(option_name)
with_condition(option_name, Hash[[[field_name, value]]])
end
# @api private
def with_prefix_condition(option_name, prefix)
field_name = field_name(option_name)
with_condition(option_name,
["starts-with", "$#{field_name}", prefix])
end
# @api private
def refine(opts)
self.class.new(bucket, {
:conditions => conditions,
:key => key,
:metadata => metadata,
:secure => secure?,
:content_length => content_length,
:expires => expires,
:ignore => ignored_fields
}.merge(@fields).
merge(opts))
end
# @api private
private
def with_condition(field, condition)
conditions = self.conditions.dup
(conditions[field] ||= []) << condition
refine(:conditions => conditions)
end
# @api private
private
def format_expiration
time =
case expires
when Time
expires
when DateTime
Time.parse(expires.to_s)
when Integer
(Time.now + expires)
when String
Time.parse(expires)
end
time.utc.iso8601
end
# @api private
private
def range_value(range)
case range
when Integer
range..range
when Range
range
end
end
# @api private
private
def split_range(range)
range = range_value(range)
[range.begin,
(range.exclude_end? ?
range.end-1 :
range.end)]
end
# @api private
private
def optional_fields
fields = @fields.keys.inject({}) do |fields, option_name|
fields[field_name(option_name)] =
field_value(option_name)
fields
end
@metadata.each do |key, value|
fields["x-amz-meta-#{key}"] = value.to_s
end
fields
end
# @api private
private
def field_name(option_name)
case option_name
when :expires_header
"Expires"
when :server_side_encryption
"x-amz-server-side-encryption"
when :key, "Key", :policy, "Policy"
option_name.to_s.downcase
when :acl, :success_action_redirect, :success_action_status
option_name.to_s
else
# e.g. Cache-Control from cache_control
field_name = option_name.to_s.tr("_", "-").
gsub(/-(.)/) { |m| m.upcase }
field_name[0,1] = field_name[0,1].upcase
field_name
end
end
# @api private
private
def field_value(option_name)
case option_name
when :acl
@fields[:acl].to_s.tr("_", "-")
when :server_side_encryption
value = @fields[:server_side_encryption]
if value.kind_of?(Symbol)
value.to_s.upcase
else
value.to_s
end
else
@fields[option_name].to_s
end
end
# @api private
private
def generate_conditions
conditions = self.conditions.inject([]) do |list, (field, field_conds)|
list + field_conds
end
conditions << { "bucket" => bucket.name }
conditions += key_conditions
conditions += optional_fields.map { |(n, v)| Hash[[[n, v]]] }
conditions += range_conditions
conditions += ignored_conditions
if token = config.credential_provider.session_token
conditions << { "x-amz-security-token" => token }
end
conditions
end
# @api private
private
def ignored_conditions
ignored_fields.map do |field|
["starts-with", "$#{field}", ""]
end
end
# @api private
private
def range_conditions
if content_length
[["content-length-range", *split_range(content_length)]]
else
[]
end
end
# @api private
private
def key_conditions
[if key && key.include?("${filename}")
["starts-with", "$key", key[/^(.*)\$\{filename\}/, 1]]
elsif key
{ "key" => key }
else
["starts-with", "$key", ""]
end]
end
# @api private
private
def build_uri(request)
uri_class = secure? ? URI::HTTPS : URI::HTTP
uri_class.build(:host => request.host,
:path => request.path,
:query => request.querystring)
end
end
end
end