docs: refine acl.conf comments

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zmstone 2024-04-25 14:04:50 +02:00
parent a67773e973
commit d30b52f0f9
1 changed files with 113 additions and 24 deletions

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@ -1,27 +1,4 @@
%%-------------------------------------------------------------------- %%-------------- Default ACL rules -------------------------------------------------------
%% -type(ipaddr() :: {ipaddr, string()}).
%%
%% -type(ipaddrs() :: {ipaddrs, [string()]}).
%%
%% -type(username() :: {user | username, string()} | {user | username, {re, regex()}}).
%%
%% -type(clientid() :: {client | clientid, string()} | {client | clientid, {re, regex()}}).
%%
%% -type(who() :: ipaddr() | ipaddrs() | username() | clientid() |
%% {'and', [ipaddr() | ipaddrs() | username() | clientid()]} |
%% {'or', [ipaddr() | ipaddrs() | username() | clientid()]} |
%% all).
%%
%% -type(action() :: subscribe | publish | all).
%%
%% -type(topic_filters() :: string()).
%%
%% -type(topics() :: [topic_filters() | {eq, topic_filters()}]).
%%
%% -type(permission() :: allow | deny).
%%
%% -type(rule() :: {permission(), who(), action(), topics()} | {permission(), all}).
%%--------------------------------------------------------------------
{allow, {username, {re, "^dashboard$"}}, subscribe, ["$SYS/#"]}. {allow, {username, {re, "^dashboard$"}}, subscribe, ["$SYS/#"]}.
@ -29,4 +6,116 @@
{deny, all, subscribe, ["$SYS/#", {eq, "#"}]}. {deny, all, subscribe, ["$SYS/#", {eq, "#"}]}.
%% NOTE: change to {deny, all} in production!
{allow, all}. {allow, all}.
%% See docs below
%%
%% ------------ The formal spec ----------------------------------------------------------
%%
%% -type ipaddr() :: {ipaddr, string()}.
%% -type ipaddrs() :: {ipaddrs, [string()]}.
%% -type username() :: {user | username, string()} | {user | username, {re, regex()}}.
%% -type clientid() :: {client | clientid, string()} | {client | clientid, {re, regex()}}.
%% -type who() :: ipaddr() | ipaddrs() | username() | clientid() |
%% {'and', [ipaddr() | ipaddrs() | username() | clientid()]} |
%% {'or', [ipaddr() | ipaddrs() | username() | clientid()]} |
%% all.
%% -type simple_action() :: subscribe | publish | all.
%% -type complex_action() :: {simple_action(), [{qos, 0..2}, {retain, true|false|all}]}.
%% -type action() :: simple_action() | complex_action().
%% -type topic() :: string().
%% -type topic_filter() :: string().
%% -type topic_match() :: topic() | topic_filter() | {eq, topic() | topic_filter()}.
%% -type perm() :: allow | deny.
%% -type rule() :: {perm(), who(), action(), [topic_match()]} | {perm(), all}.
%%-------------- Viusal aid for the spec -------------------------------------------------
%%
%% rule()
%% ├── {perm(), who(), action(), [topic_match()]}
%% │ │ │ │ ├── topic() :: string()
%% │ │ │ │ ├── topic_filter() :: string()
%% │ │ │ │ └── {eq, topic() | topic_filter()}
%% │ │ │ │
%% │ │ │ ├── simple_action()
%% │ │ │ │ ├── publish
%% │ │ │ │ ├── subscribe
%% │ │ │ │ └── all
%% │ │ │ └── {simple_action(), [{qos,0..2},{retain,true|false|all}]}
%% │ │ │
%% │ │ ├── ipaddr()
%% │ │ │ └── {ipaddr, string()}
%% │ │ ├── ipaddrs()
%% │ │ │ └── {ipaddrs, [string()]}
%% │ │ ├── username()
%% │ │ │ ├── {user | username, string()}
%% │ │ │ └── {user | username, {re, regex()}}
%% │ │ ├── clientid()
%% │ │ │ ├── {client | clientid, string()}
%% │ │ │ └── {client | clientid, {re, regex()}}
%% │ │ ├── {'and', [ipaddr() | ipaddrs() | username() | clientid()]}
%% │ │ ├── {'or', [ipaddr() | ipaddrs() | username() | clientid()]}
%% │ │ └── all
%% │ │
%% │ ├── allow
%% │ └── deny
%% │
%% └── {perm(), all}
%%
%% This file defines a set of ACL rules for MQTT client pub/sub authorization.
%% The content is of Erlang-term format.
%% Each Erlang-term is a tuple `{...}` terminated by dot `.`
%%
%% NOTE: When deploy to production, the last rule should be changed to {deny, all}.
%%
%% NOTE: It's a good practice to keep the nubmer of rules small, because in worst case
%% scenarios, all rules have to be traversed for each message publish.
%%
%% A rule is a 4-element tuple.
%% For example, `{allow, {username, "Jon"}, subscribe, ["#"]}` allows Jon to subscribe to
%% any topic they want.
%%
%% Below is an explanation:
%%
%% - `perm()`: The permission.
%% Defines whether this is an `allow` or `deny` rule.
%%
%% - `who()`: The MQTT client matching condition.
%% - `all`: A rule which applies to all clients.
%% - `{ipaddr, IpAddress}`: Matches a client by source IP address. CIDR notation is allowed.
%% - `{ipaddrs, [IpAddress]}`: Matches clients by a set of IP addresses. CIDR notation is allowed.
%% - `{clientid, ClientID}`: Matches a client by ID.
%% - `{username, Username}`: Matches a client by username.
%% - `{..., {re, ..}}`: Regular expression to match either clientid or username.
%% - `{'and', [...]}`: Combines a list of matching conditions.
%% - `{'or', [...]}`: Combines a list of matching conditions.
%%
%% - `action()`: Matches publish or subscribe actions (or both).
%% Applies the rule to `publish` or `subscribe` actions.
%% The special value `all` denotes allowing or denying both `publish` and `subscribe`.
%% It can also be associated with `qos` and `retain` flags to match the action with
%% more specifics. For example, `{publish, [{qos,0},{retain,false}]}` should only
%% match the `publish` action when the message has QoS 0, and without retained flag set.
%%
%% - `[topic_match()]`:
%% A list of topics, topic-filters, or template rendering to match the topic being
%% subscribed to or published.
%% For example, `{allow, {username, "Jan"}, publish, ["jan/#"]}` permits Jan to publish
%% to any topic matching the wildcard pattern "jan/#".
%% A special tuple `{eq, topic_match()}` is useful to allow or deny the specific wildcard
%% subscription instead of performing a topic match.
%% A `topic_match()` can also contain a placeholder rendered with actual value at runtime,
%% for example, `{allow, all, publish, "${clientid}/#"}` allows all clients to publish to
%% topics prefixed by their own client ID.
%%
%% Supported placeholders are:
%% - `${cn}`: TLS certificate common name.
%% - `${clientid}`: The client ID.
%% - `${username}`: The username.
%% - `${client_attrs.NAME}`: A client attribute named `NAME`, which can be initialized by
%% `mqtt.client_attrs_init` config or extended by certain authentication backends.
%% NOTE: Placeholder is not rendered as empty string if the referencing value is not
%% foud. For example, `${client_attrs.group}/#` is not rendered as `/#` if the
%% client does not have a `group` attribute.