Details
Major Description
I tested the Stomp acceptor handling of escape sequences as specified in the 1.2 protocol documentation.
With ActiveMQ Artemis 2.19.0, all escape sequences are received according to the 1.2 specification:
https://stomp.github.io/stomp-specification-1.2.html#Value_Encoding
With ActiveMQ "Classic" however, there is a difference: when the escape sequence \r is used in SEND frame header values, it will be received as \\r in incoming MESSAGE frames.
Test with Artemis 2.19.0
The first example uses the Artemis broker. A message with four special escaped characters (backslash, colon, newline and carriage return) is sent to the broker and then received with identical values.
As you can see in the example, the header property keyr in the outgoing SEND frame has the value value\r and is received as value\r in the incoming MESSAGE frame.
Unescaped, this is "value" + carriage return
CONNECTED
version:1.2
session:be014f64
server:ActiveMQ-Artemis/2.19.0 ActiveMQ Artemis Messaging Engine
SEND
destination:queue/TStomp12TestCase.TestEscapes.Q
keyb:value\\
keyc:value\c
keyn:value\n
keyr:value\r
content-type:text/plain
Send:Bytes:112
SUBSCRIBE
destination:queue/TStomp12TestCase.TestEscapes.Q
ack:auto
id:{13084522-1FEF-4B8A-802A-4656A77784EA}
MESSAGE
subscription:{13084522-1FEF-4B8A-802A-4656A77784EA}
message-id:10737418259
destination:queue/TStomp12TestCase.TestEscapes.Q
expires:0
redelivered:false
priority:4
persistent:false
timestamp:1636280945342
content-type:text/plain
keyn:value\n
keyc:value\c
keyb:value\\
keyr:value\r
Test with ActiveMQ 5.16.3
As you can see in the example, the header property keyr in the outgoing SEND frame has the value value\r (as in the first test) but is received as value\\r in the incoming MESSAGE frame. Unescaped, this is not "value" + carriage return, but "value\r".
CONNECTED
server:ActiveMQ/5.16.3
heart-beat:0,0
session:ID:DESKTOP-3LKMPLS-49926-1636281770555-3:4
version:1.2
SEND
destination:/queue/TStomp12TestCase.TestEscapes.Q
keyb:value\\
keyc:value\c
keyn:value\n
keyr:value\r
content-type:text/plain
SUBSCRIBE
destination:/queue/TStomp12TestCase.TestEscapes.Q
ack:auto
id:{7316E53E-E7C3-43DC-B2EF-75BCFC09D899}
MESSAGE
keyr:value\\r
expires:0
destination:/queue/TStomp12TestCase.TestEscapes.Q
subscription:{7316E53E-E7C3-43DC-B2EF-75BCFC09D899}
priority:4
keyb:value\\
keyc:value\c
message-id:ID\cDESKTOP-3LKMPLS-49926-1636281770555-3\c4\c-1\c1\c1
content-type:text/plain
keyn:value\n
timestamp:1636281794663
So it seems that ActiveMQ Classic performs either an incorrect unescaping on the incoming message, or an incorrect escaping on the outgoing message.
