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mod_http_oauth2: Implement RFC 7628 Proof Key for Code Exchange Likely to become mandatory in OAuth 2.1. Backwards compatible since the default 'plain' verifier would compare nil with nil if the relevant parameters are left out.
author Kim Alvefur <zash@zash.se>
date Sat, 29 Apr 2023 13:09:46 +0200
parents 18774cc621d6
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---
labels:
- 'Stage-Stable'
summary: Publish to PubSub nodes from via HTTP POST/WebHooks
---

# Introduction

This module is a fairly generic WebHook receiver that lets you easily
publish data to PubSub using a HTTP POST request. The payload can be
Atom feeds, arbitrary XML, or arbitrary JSON. The type should be
indicated via the `Content-Type` header.

-   JSON data is wrapped in a [XEP-0335] container.
-   An Atom feed may have many `<entry>` and each one is published as
    its own PubSub item.
-   Other XML is simply published to the item with ID `current`.

## JSON example

``` {.bash}
curl http://localhost:5280/pubsub_post/princely_musings \
    -H "Content-Type: application/json" \
    --data-binary '{"musing":"To be, or not to be: that is the question"}'
```

## Atom example

``` {.bash}
curl http://localhost:5280/pubsub_post/princely_musings \
    -H "Content-Type: application/xml" \
    --data-binary '<feed xmlns="http://www.w3.org/2005/Atom">
        <entry><title>Hello</title></entry></feed>'
```

## Simple form-data

``` {.bash}
curl http://localhost:5280/pubsub_post/princely_musings \
    --data musing="To be, or not to be: that is the question"
```

# Configuration

All settings are optional.

## Actor identification

First we have to figure out who is making the request.
This is configured on a per-node basis like this:

``` {.lua}
-- Per node secrets
pubsub_post_actors = {
    princely_musings = "hamlet@denmark.lit"
}
pubsub_post_default_actor = "nobody@nowhere.invalid"
```

`pubsub_post_default_actor` is used when trying to publish to a node
that is not listed in `pubsub_post_actors`. Otherwise the IP address
of the connection is used.

## Authentication

[WebSub](https://www.w3.org/TR/2018/REC-websub-20180123/) [Authenticated
Content
Distribution](https://www.w3.org/TR/2018/REC-websub-20180123/#authenticated-content-distribution)
authentication is used.

``` {.lua}
pubsub_post_secrets = {
    princely_musings = "shared secret"
}
pubsub_post_default_secret = "default secret"
```

`pubsub_post_default_secret` is used when trying to publish to a node
that is not listed in `pubsub_post_secrets`. Otherwise the request
proceeds with the previously identified actor.

::: {.alert .alert-danger}
If configured without a secret and a default actor that has permission
to create nodes the service becomes wide open.
:::

## Authorization

Authorization is handled via pubsub affiliations. Publishing requires an
affiliation with the _publish_ capability, usually `"publisher"`.

### Setting up affiliations

Prosodys PubSub module supports [setting affiliations via
XMPP](https://xmpp.org/extensions/xep-0060.html#owner-affiliations),
since 0.11.0, so affiliations can be configured with a capable client.

It can however be done from another plugin:

``` {.lua}
local mod_pubsub = module:depends("pubsub");
local pubsub = mod_pubsub.service;

pubsub:create("princely_musings", true);
pubsub:set_affiliation("princely_musings", true, "127.0.0.1", "publisher");
```

## Data mappings

The datamapper library added in 0.12.0 allows posting JSON and having it
converted to XML based on a special JSON Schema.

``` json
{
   "properties" : {
      "content" : {
         "type" : "string"
      },
      "title" : {
         "type" : "string"
      }
   },
   "type" : "object",
   "xml" : {
      "name" : "musings",
      "namespace" : "urn:example:princely"
   }
}
```

And in the Prosody config file:

``` lua
pubsub_post_mappings = {
    princely_musings = "musings.json";
}
```

Then, POSTing a JSON payload like

``` json
{
   "content" : "To be, or not to be: that is the question",
   "title" : "Soliloquy"
}
```

results in a payload like

``` xml
<musings xmlns="urn:example:princely">
  <title>Soliloquy</title>
  <content>To be, or not to be: that is the question</content>
</musings>
```

being published to the node.