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57c2690f7e
As curl now supports TLS (mqtts), it is no longer necessary to list it as a limitation in the docs. Closes #20343
62 lines
1.3 KiB
Markdown
62 lines
1.3 KiB
Markdown
<!--
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Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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-->
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# MQTT in curl
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## Usage
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A plain "GET" subscribes to the topic and prints all published messages.
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Doing a "POST" publishes the post data to the topic and exits.
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## TLS protection
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Use `mqtts://` to do MQTT over TLS: MQTTS.
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### Subscribing
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Command usage:
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curl mqtt://host/topic
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Example subscribe:
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curl mqtt://host.home/bedroom/temp
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This sends an MQTT SUBSCRIBE packet for the topic `bedroom/temp` and listen in
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for incoming PUBLISH packets.
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You can set the upkeep interval ms option to make curl send MQTT ping requests
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to the server at an internal, to prevent the connection to get closed because
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of idleness. You might then need to use the progress callback to cancel the
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operation.
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### Publishing
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Command usage:
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curl -d payload mqtt://host/topic
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Example publish:
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curl -d 75 mqtt://host.home/bedroom/dimmer
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This sends an MQTT PUBLISH packet to the topic `bedroom/dimmer` with the
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payload `75`.
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## What does curl deliver as a response to a subscribe
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Whenever a PUBLISH packet is received, curl outputs two bytes topic length
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(MSB | LSB), the topic followed by the payload.
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## Caveats
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Remaining limitations:
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- Only QoS level 0 is implemented for publish
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- No way to set retain flag for publish
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- Naive EAGAIN handling does not handle split messages
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