Log clearer message if TLS client connects to AMQP port (backport #13559) #13560
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## What?
If a TLS client app is misconfigured trying to connect to AMQP port 5672
instead to the AMQPS port 5671, this commit makes RabbitMQ log a more
descriptive error message.
```
openssl s_client -connect localhost:5672 -tls1_3
openssl s_client -connect localhost:5672 -tls1_2
```
RabbitMQ logs prior to this commit:
```
[info] <0.1073.0> accepting AMQP connection [::1]:53535 -> [::1]:5672
[error] <0.1073.0> closing AMQP connection <0.1073.0> ([::1]:53535 -> [::1]:5672, duration: '0ms'):
[error] <0.1073.0> {bad_header,<<22,3,1,0,192,1,0,0>>}
[info] <0.1080.0> accepting AMQP connection [::1]:53577 -> [::1]:5672
[error] <0.1080.0> closing AMQP connection <0.1080.0> ([::1]:53577 -> [::1]:5672, duration: '1ms'):
[error] <0.1080.0> {bad_header,<<22,3,1,0,224,1,0,0>>}
```
RabbitMQ logs after this commit:
```
[info] <0.969.0> accepting AMQP connection [::1]:53632 -> [::1]:5672
[error] <0.969.0> closing AMQP connection <0.969.0> ([::1]:53632 -> [::1]:5672, duration: '0ms'):
[error] <0.969.0> {detected_unexpected_tls_header,<<22,3,1,0,192,1,0,0>>
[info] <0.975.0> accepting AMQP connection [::1]:53638 -> [::1]:5672
[error] <0.975.0> closing AMQP connection <0.975.0> ([::1]:53638 -> [::1]:5672, duration: '1ms'):
[error] <0.975.0> {detected_unexpected_tls_header,<<22,3,1,0,224,1,0,0>>}
```
## Why?
I've seen numerous occurrences in the past few years where misconfigured TLS apps
connected to the wrong port. Therefore, RabbitMQ trying to detect a TLS client
and providing a more descriptive log message seems appropriate to me.
## How?
The first few bytes of any TLS connection are:
Record Type (1 byte):
Always 0x16 (22 in decimal) for a Handshake message.
Version (2 bytes):
This represents the highest version of TLS that the client supports. Common values:
0x0301 → TLS 1.0 (or SSL 3.1)
0x0302 → TLS 1.1
0x0303 → TLS 1.2
0x0304 → TLS 1.3
Record Length (2 bytes):
Specifies the length of the following handshake message.
Handshake Type (1 byte, usually the 6th byte overall):
Always 0x01 for ClientHello.
(cherry picked from commit 7ed3a0b)
It also happens from time to time that HTTP clients use the wrong port
5672. Like for TLS clients connecting to 5672, RabbitMQ now prints a
more descriptive log message.
For example
```
curl http://localhost:5672
```
will log
```
[info] <0.946.0> accepting AMQP connection [::1]:57736 -> [::1]:5672
[error] <0.946.0> closing AMQP connection <0.946.0> ([::1]:57736 -> [::1]:5672, duration: '1ms'):
[error] <0.946.0> {detected_unexpected_http_header,<<"GET / HT">>}
```
We only check here for GET and not for all other HTTP methods, since
that's the most common case.
(cherry picked from commit 11e56bd)
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What?
If a TLS client app is misconfigured trying to connect to AMQP port 5672 instead to the AMQPS port 5671, this commit makes RabbitMQ log a more descriptive error message.
RabbitMQ logs prior to this commit:
RabbitMQ logs after this commit:
Why?
I've seen numerous occurrences in the past few years where misconfigured TLS apps connected to the wrong port. Therefore, RabbitMQ trying to detect a TLS client and providing a more descriptive log message seems appropriate to me.
How?
The first few bytes of any TLS connection are:
Record Type (1 byte):
Always 0x16 (22 in decimal) for a Handshake message.
Version (2 bytes):
This represents the highest version of TLS that the client supports. Common values: 0x0301 → TLS 1.0 (or SSL 3.1)
0x0302 → TLS 1.1
0x0303 → TLS 1.2
0x0304 → TLS 1.3
Record Length (2 bytes):
Specifies the length of the following handshake message.
Handshake Type (1 byte, usually the 6th byte overall): Always 0x01 for ClientHello.
This is an automatic backport of pull request #13559 done by Mergify.