summary refs log tree commit diff
path: root/synapse/config/oembed.py
blob: 3631cea96fdee5473cfe12f2cd936aa909aa5bda (plain) (blame)
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
#
# This file is licensed under the Affero General Public License (AGPL) version 3.
#
# Copyright (C) 2023 New Vector, Ltd
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# See the GNU Affero General Public License for more details:
# <https://www.gnu.org/licenses/agpl-3.0.html>.
#
# Originally licensed under the Apache License, Version 2.0:
# <http://www.apache.org/licenses/LICENSE-2.0>.
#
# [This file includes modifications made by New Vector Limited]
#
#
import json
import re
from typing import Any, Dict, Iterable, List, Optional, Pattern
from urllib import parse as urlparse

import attr
import pkg_resources

from synapse.types import JsonDict, StrSequence

from ._base import Config, ConfigError
from ._util import validate_config


@attr.s(slots=True, frozen=True, auto_attribs=True)
class OEmbedEndpointConfig:
    # The API endpoint to fetch.
    api_endpoint: str
    # The patterns to match.
    url_patterns: List[Pattern[str]]
    # The supported formats.
    formats: Optional[List[str]]


class OembedConfig(Config):
    """oEmbed Configuration"""

    section = "oembed"

    def read_config(self, config: JsonDict, **kwargs: Any) -> None:
        oembed_config: Dict[str, Any] = config.get("oembed") or {}

        # A list of patterns which will be used.
        self.oembed_patterns: List[OEmbedEndpointConfig] = list(
            self._parse_and_validate_providers(oembed_config)
        )

    def _parse_and_validate_providers(
        self, oembed_config: dict
    ) -> Iterable[OEmbedEndpointConfig]:
        """Extract and parse the oEmbed providers from the given JSON file.

        Returns a generator which yields the OidcProviderConfig objects
        """
        # Whether to use the packaged providers.json file.
        if not oembed_config.get("disable_default_providers") or False:
            with pkg_resources.resource_stream("synapse", "res/providers.json") as s:
                providers = json.load(s)

            yield from self._parse_and_validate_provider(
                providers, config_path=("oembed",)
            )

        # The JSON files which includes additional provider information.
        for i, file in enumerate(oembed_config.get("additional_providers") or []):
            # TODO Error checking.
            with open(file) as f:
                providers = json.load(f)

            yield from self._parse_and_validate_provider(
                providers,
                config_path=(
                    "oembed",
                    "additional_providers",
                    f"<item {i}>",
                ),
            )

    def _parse_and_validate_provider(
        self, providers: List[JsonDict], config_path: StrSequence
    ) -> Iterable[OEmbedEndpointConfig]:
        # Ensure it is the proper form.
        validate_config(
            _OEMBED_PROVIDER_SCHEMA,
            providers,
            config_path=config_path,
        )

        # Parse it and yield each result.
        for provider in providers:
            # Each provider might have multiple API endpoints, each which
            # might have multiple patterns to match.
            for endpoint in provider["endpoints"]:
                api_endpoint = endpoint["url"]

                # The API endpoint must be an HTTP(S) URL.
                results = urlparse.urlparse(api_endpoint)
                if results.scheme not in {"http", "https"}:
                    raise ConfigError(
                        f"Unsupported oEmbed scheme ({results.scheme}) for endpoint {api_endpoint}",
                        config_path,
                    )

                patterns = [
                    self._glob_to_pattern(glob, config_path)
                    for glob in endpoint["schemes"]
                ]
                yield OEmbedEndpointConfig(
                    api_endpoint, patterns, endpoint.get("formats")
                )

    def _glob_to_pattern(self, glob: str, config_path: StrSequence) -> Pattern:
        """
        Convert the glob into a sane regular expression to match against. The
        rules followed will be slightly different for the domain portion vs.
        the rest.

        1. The scheme must be one of HTTP / HTTPS (and have no globs).
        2. The domain can have globs, but we limit it to characters that can
           reasonably be a domain part.
           TODO: This does not attempt to handle Unicode domain names.
           TODO: The domain should not allow wildcard TLDs.
        3. Other parts allow a glob to be any one, or more, characters.
        """
        results = urlparse.urlparse(glob)

        # The scheme must be HTTP(S) (and cannot contain wildcards).
        if results.scheme not in {"http", "https"}:
            raise ConfigError(
                f"Unsupported oEmbed scheme ({results.scheme}) for pattern: {glob}",
                config_path,
            )

        pattern = urlparse.urlunparse(
            [
                results.scheme,
                re.escape(results.netloc).replace("\\*", "[a-zA-Z0-9_-]+"),
            ]
            + [re.escape(part).replace("\\*", ".+") for part in results[2:]]
        )
        return re.compile(pattern)


_OEMBED_PROVIDER_SCHEMA = {
    "type": "array",
    "items": {
        "type": "object",
        "properties": {
            "provider_name": {"type": "string"},
            "provider_url": {"type": "string"},
            "endpoints": {
                "type": "array",
                "items": {
                    "type": "object",
                    "properties": {
                        "schemes": {
                            "type": "array",
                            "items": {"type": "string"},
                        },
                        "url": {"type": "string"},
                        "formats": {"type": "array", "items": {"type": "string"}},
                        "discovery": {"type": "boolean"},
                    },
                    "required": ["schemes", "url"],
                },
            },
        },
        "required": ["provider_name", "provider_url", "endpoints"],
    },
}