The I2P Network Protocol (I2NP), which is sandwiched between I2CP and the various I2P transport protocols, manages the routing and mixing of messages between routers, as well as the selection of what transports to use when communicating with a peer for which there are multiple common transports supported.
| Message | Type |
| DatabaseStore | 1 |
| DatabaseLookup | 2 |
| DatabaseSearchReply | 3 |
| DeliveryStatus | 10 |
with reply token: +----+----+----+----+----+----+----+----+ | SHA256 Hash as key | + + | | + + | | + + | | +----+----+----+----+----+----+----+----+ |type| reply token | reply tunnel- +----+----+----+----+----+----+----+----+ Id | SHA256 of the gateway RouterInfo | +----+ + | | + + | | + + | | + +----+----+----+----+----+----+----+ | | data ... +----+--------\\ with reply token == 0: +----+----+----+----+----+----+----+----+ | SHA256 Hash as key | + + | | + + | | + + | | +----+----+----+----+----+----+----+----+ |type| reply token | data ... +----+-------------------+---------\\
key:
32 bytes
SHA256 hash
type:
1 byte
type identifier
mapping:
0 RouterInfo
1 LeaseSet
reply token:
4 bytes
TODO: find out what this does
reply tunnelId:
4 bytes
only included if reply token > 0
TODO: what this tunnel information is needed for
reply gateway:
32 bytes
Hash of the routerInfo entry to reach the gateway
only included if reply token > 0
TODO: what this tunnel information is needed for
data:
rest of the message(could be anything)
{% filter escape %}
if flag==TRUE
+----+----+----+----+----+----+----+----+
| SHA256 hash as the key to look up |
+ +
| |
+ +
| |
+ +
| |
+----+----+----+----+----+----+----+----+
| SHA256 hash of the routerInfo |
+ who is asking +
| |
+ +
| |
+ +
| |
+----+----+----+----+----+----+----+----+
|flag| reply tunnelId |size | |
+----+----+----+----+----+----+----+ +
| SHA256 of $key1 to exclude |
+ +
| |
+ +
| |
+ +----+
| | |
+----+----+----+----+----+----+----+ +
| SHA256 of $key2 to exclude |
....
{% endfilter %}
{% filter escape %}
key:
32 bytes
SHA256 hash of the object to lookup
from:
32 bytes
SHA256 hash of the routerInfo entry this request came from(and to which the reply should be sent)
flag:
1 byte
mapping:
0 FALSE => send reply directly
1 TRUE => send reply to some tunnel
reply tunnelId:
2 bytes
only included if flag==TRUE
tunnelId of the tunnel to send the reply to
size:
2 bytes
number of peers to exclude from the lookup(TODO: whatever this means)
excludedPeers:
rest of the message are $size SHA256 hashes of 32 bytes each(total $size*32 bytes)
{% endfilter %}
{% filter escape %}
+----+----+----+----+----+----+----+----+
| SHA256 hash as query key |
+ +
| |
+ +
| |
+ +
| |
+----+----+----+----+----+----+----+----+
|num | peer hash $1 |
+----+ +
| |
+ +
| |
+ +
| |
+ +----+----+----+----+----+----+----+
| | |
+----+.... $num peer hashes
+ +----+----+----+----+----+----+----+
| | from |
+----+ +
| |
+ +
| |
+ +
| |
+ +----+----+----+----+----+----+----+
| |
+----+
{% endfilter %}
Definition
{% filter escape %}
key:
32 bytes
SHA256 of the object being searched
num:
1 byte
number of peer hashes that follow
peer hash:
32 bytes
SHA256 of the RouterInfo that the other router thinks are close to the key
$num entries
from:
32 bytes
SHA256 of the RouterInfo of the router this reply was sent from
{% endblock %}
DeliveryStatus
{% filter escape %}
+----+----+----+----+----+----+----+----+----+----+----+----+
|msg-id | arrival-time |
+----+----+----+----+----+----+----+----+----+----+----+----+
{% endfilter %}
Definition
{% filter escape %}
msg-id:
4 bytes
unique ID of the message we deliver the DeliveryStatus for(see common I2NP header for details)
arrival-time:
8 bytes
time the message was successfully delivered
{% endfilter %}