Fix Block1 transfer handling for non-piggybacked responses #394
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Fix Block1 transfer completion when server sends non-piggybacked responses. Previously, only ACK messages with Block1 options were processed for Block1 transfers, causing premature completion when servers send separate CON/NON messages with Block1 responses after sending ACK. RFC 7959 allows Block1 responses to be sent as separate messages (non-piggybacked) and these should be processed regardless of whether they are confirmable or not.
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Thanks @stoprocent :-) (long time no see ...) LGTM. @JKRhb WDYT? Updating deps and release after merge? |
Apollon77
approved these changes
Jul 14, 2025
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Pull Request Test Coverage Report for Build 16274004738Details
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Hey @JKRhb |
JKRhb
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Jul 15, 2025
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JKRhb
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Hi @stoprocent, thank you for your comprehensive PR! LGTM :)
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Problem
The node-coap client was incorrectly handling Block1 transfers when servers send non-piggybacked responses. Specifically, when a server:
The client would prematurely complete the Block1 transfer because it only processed Block1 options on ACK messages.
Root Cause
The condition
if (block1 != null && packet.ack)inlib/agent.tswas too restrictive. It only processed Block1 options when the packet was an ACK, but RFC 7959 allows Block1 responses to be sent as separate messages (non-piggybacked).Solution
Changed the condition to
if (block1 != null)to process Block1 options regardless of message type. This handles:RFC Compliance
According to RFC 7959 (Block Transfer), Block1 responses can be sent either:
The fix ensures compliance with both approaches.
Testing
Files Changed
lib/agent.ts: Modified Block1 processing condition to handle all message typesThis fix resolves issues when communicating with third-party CoAP servers that implement non-piggybacked Block1 responses.