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prop. 160 updates

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2025-04-27 14:50:44 -04:00
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i2p2www/spec/proposals/160-udp-trackers.rst
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@ -76,10 +76,12 @@ overhead where possible before PQ crypto is adopted in I2P.
Design Design
============ ============
This proposal uses both repliable datagram2 and raw datagrams, This proposal uses repliable datagram2, repliable datagram3, and raw datagrams,
as defined in [DATAGRAMS]_. as defined in [DATAGRAMS]_.
Datagram2 is a new variant of repliable datagrams, Datagram2 and Datagram3 are new variants of repliable datagrams,
defined in Proposal 163 [Prop163]_, that adds replay resistance. defined in Proposal 163 [Prop163]_.
Datagram2 adds replay resistance and offline signature support.
Datagram3 is smaller than the old datagram format, but without authentication.
BEP 15 BEP 15
@ -113,9 +115,9 @@ for efficiency, and for security reasons discussed below:
Client Tracker Client Tracker
Connect Req. -------------> (Repliable Datagram2) Connect Req. -------------> (Repliable Datagram2)
<-------------- Connect Resp. (Raw) <-------------- Connect Resp. (Raw)
Announce Req. -------------> (Raw) Announce Req. -------------> (Repliable Datagram3)
<-------------- Announce Resp. (Raw) <-------------- Announce Resp. (Raw)
Announce Req. -------------> (Raw) Announce Req. -------------> (Repliable Datagram3)
<-------------- Announce Resp. (Raw) <-------------- Announce Resp. (Raw)
... ...
{% endhighlight %} {% endhighlight %}
@ -124,8 +126,16 @@ This potentially provides a large bandwidth savings over
streaming (TCP) announces. streaming (TCP) announces.
While the Datagram2 is about the same size as a streaming SYN, While the Datagram2 is about the same size as a streaming SYN,
the raw response is much smaller than the streaming SYN ACK. the raw response is much smaller than the streaming SYN ACK.
All subsequent requests/responses are raw. Subsequent requests use Datagram3, and the subsequent responses are raw.
The announce requests are Datagram3 so that the tracker need not
maintain a large mapping table of connection IDs to announce destination or hash.
Instead, the tracker may generate connection IDs cryptographically
from the sender hash, the current timestamp (based on some interval),
and a secret value.
When an announce request is received, the tracker validates the
connection ID, and then uses the
Datagram3 sender hash as the send target.
Tracker/Client support Tracker/Client support
@ -224,8 +234,10 @@ Specification
Protocols and Ports Protocols and Ports
------------------- -------------------
Repliable Datagram2 uses I2CP protocol 19; raw datagrams use I2CP protocol 18. Repliable Datagram2 uses I2CP protocol 19;
Requests may be Datagram2 or raw. Responses are always raw. repliable Datagram3 uses I2CP protocol 20;
raw datagrams use I2CP protocol 18.
Requests may be Datagram2 or Datagram3. Responses are always raw.
The older repliable datagram ("Datagram1") format using I2CP protocol 17 The older repliable datagram ("Datagram1") format using I2CP protocol 17
must NOT be used for requests or replies; these must be dropped if received must NOT be used for requests or replies; these must be dropped if received
on the request/reply ports. Note that Datagram1 protocol 17 on the request/reply ports. Note that Datagram1 protocol 17
@ -313,7 +325,7 @@ Announce Request
```````````````` ````````````````
Client to tracker. Client to tracker.
98 bytes minimum. Must be raw. Same as in [BEP15]_ except as noted below. 98 bytes minimum. Must be repliable Datagram3. Same as in [BEP15]_ except as noted below.
The connection_id is as received in the connect response. The connection_id is as received in the connect response.
@ -405,7 +417,8 @@ Scrape
Scrape request/response from [BEP15]_ is not required by this proposal, Scrape request/response from [BEP15]_ is not required by this proposal,
but may be implemented if desired, no changes required. but may be implemented if desired, no changes required.
The client must acquire a connection ID first. The client must acquire a connection ID first.
The scrape request and response are always raw. The scrape request is always repliable Datagram3.
The scrape response is always raw.
@ -485,7 +498,7 @@ Trackers
Trackers with existing BEP 15 support should require only small modifications. Trackers with existing BEP 15 support should require only small modifications.
This proposal differs from the 2014 proposal, in that the tracker This proposal differs from the 2014 proposal, in that the tracker
must support reception of repliable datagram2 and raw datagrams on the same port. must support reception of repliable datagram2 and datagram3 on the same port.
@ -494,7 +507,7 @@ Migration
Existing clients do not support UDP announce URLs and ignore them. Existing clients do not support UDP announce URLs and ignore them.
Existing trackers do not support reception of repliable datagram2 or raw datagrams, they will be dropped. Existing trackers do not support reception of repliable or raw datagrams, they will be dropped.
This proposal is completely optional. Neither clients nor trackers are required to implement it at any time. This proposal is completely optional. Neither clients nor trackers are required to implement it at any time.