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minor punctuation fixes

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only minor punctuation fixes. not changed the wording, except for one 'logical typo'.
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aaannndddyyy 2015-03-05 09:19:35 +00:00
parent 6c37f490e0
commit 1e17b468e6
1 changed files with 34 additions and 34 deletions
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68
docs/Tox_middle_level_network_protocol.txt
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@ -3,58 +3,58 @@ feature complete. Why doesn't Tox support TCP yet even if those parts are
complete? complete?
The answer is that a way to ensure a smooth switchover between the TCP and UDP The answer is that a way to ensure a smooth switchover between the TCP and UDP
needs to be added. If Tox first connects to the other user using TCP but then needs to be added. If Tox first connects to the other user using TCP but then,
due to pure chance manages to connect using the faster direct UDP connection due to pure chance, manages to connect using the faster direct UDP connection,
Tox must switch seamlessly from the TCP to the UDP connection without there Tox must switch seamlessly from the TCP to the UDP connection without there
being any data loss or the other user going offline and then back online. The being any data loss or the other user going offline and then back online. The
transition must be seamless whatever both connected users are doing be it transition must be seamless whatever both connected users are doing - be it
transferring files or simply chatting together. transferring files or simply chatting together.
Possible evil/bad or simply TCP relays going offline must not impact the Possible evil/bad or simply TCP relays going offline must not impact the
connection between both clients. connection between both clients.
Typically Tox will use more than one TCP relay to connect to other peers for Typically, Tox will use more than one TCP relay to connect to other peers for
maximum connection stability which means there must be a way for Tox to take maximum connection stability, which means there must be a way for Tox to take
advantage of multiple relays in a way that the user will never be aware if one advantage of multiple relays in a way that the user will never be aware of, if one
of them goes offline/tries to slow down the connection/decides to corrupt of them goes offline/tries to slow down the connection/decides to corrupt
packets/etc.. packets/etc.
To accomplish this Tox needs something between the low level protocol (TCP) and To accomplish this, Tox needs something between the low level protocol (TCP) and
high level Tox messaging protocol hence the name middle level. high level Tox messaging protocol; hence the name middle level.
The plan is to move some functionality from lossless_UDP to a higher level: The plan is to move some functionality from lossless_UDP to a higher level:
more specifically the functionality for detecting which packets a peer is more specifically, the functionality for detecting which packets a peer is
missing and the ability to request and send them again. lossless UDP uses plain missing, and the ability to request and send them again. Lossless UDP uses plain
text packets to request missing packets from the other peer while Tox is text packets to request missing packets from the other peer, while Tox is
currently designed to kill the connection if any packet tampering is detected. currently designed to kill the connection if any packet tampering is detected.
This works very well when connecting directly with someone because if the This works very well when connecting directly with someone because if the
attacker can modify packets it means he can kill your connection anyways. With attacker can modify packets, it means he can kill your connection anyway. With
TCP relays however that is not the case as such the packets used to request TCP relays, however, that is not the case. As such the packets used to request
missing packets must be encrypted. If it is detected that a packet has been missing packets must be encrypted. If it is detected that a packet has been
tampered, the connection must stay intact while the evil relay must be tampered, the connection must stay intact while the evil relay must be
disconnected from and replaced with a good relay, the behavior must be the same disconnected from and replaced with a good relay; the behavior must be the same
as if the relay had just suddenly gone online. Of course something to protect as if the relay had just suddenly gone offline. Of course, something to protect
from evil "friends" framing relays must also be implemented. from evil "friends" framing relays must also be implemented.
Detailed implementation details: Detailed implementation details:
cookie request packet: cookie request packet:
[uint8_t 24][Senders DHT Public key (32 bytes)][Random nonce (24 [uint8_t 24][Sender's DHT Public key (32 bytes)][Random nonce (24
bytes)][Encrypted message containing: [Senders real public key (32 bytes)][Encrypted message containing: [Sender's real public key (32
bytes)][padding (32 bytes)][uint64_t number (must be sent bytes)][padding (32 bytes)][uint64_t number (must be sent
back untouched in cookie response)]] back untouched in cookie response)]]
Encrypted message is encrypted with sender DHT private key, receivers DHT Encrypted message is encrypted with sender's DHT private key, receiver's DHT
public key and the nonce. public key and the nonce.
cookie response packet: cookie response packet:
[uint8_t 25][Random nonce (24 bytes)][Encrypted message containing: [uint8_t 25][Random nonce (24 bytes)][Encrypted message containing:
[Cookie][uint64_t number (that was sent in the request)]] [Cookie][uint64_t number (that was sent in the request)]]
Encrypted message is encrypted with sender DHT private key, receivers DHT Encrypted message is encrypted with sender's DHT private key, receiver's DHT
public key and the nonce. public key and the nonce.
The Cookie should be basically: The Cookie should be basically:
[nonce][encrypted data:[uint64_t time][Senders real public key (32 [nonce][encrypted data:[uint64_t time][Sender's real public key (32
bytes)][Senders dht public key (32 bytes)]] bytes)][Sender's DHT public key (32 bytes)]]
Handshake packet: Handshake packet:
[uint8_t 26][Cookie][nonce][Encrypted message containing: [random 24 bytes base [uint8_t 26][Cookie][nonce][Encrypted message containing: [random 24 bytes base
@ -66,25 +66,25 @@ The handshake packet is encrypted using the real private key of the sender, the
real public key of the receiver and the nonce. real public key of the receiver and the nonce.
Alice wants to connect to bob. Alice wants to connect to Bob:
Alice sends a cookie request packet to bob and gets a cookie response back. Alice sends a cookie request packet to Bob and gets a cookie response back.
Alice then generates a nonce and a temporary public/private keypair. Alice then generates a nonce and a temporary public/private keypair.
Alice then takes that nonce and just generated private key, the obtained Alice then takes that nonce and just generated private key, the obtained
cookie, creates a new cookie and puts them in a handshake packet which she cookie, creates a new cookie and puts them in a handshake packet, which she
sends to bob. sends to Bob.
Bob gets the handshake packet, accepts the connection request, then generates a Bob gets the handshake packet, accepts the connection request, then generates a
nonce and a temporary public/private keypair and sends a handshake packet back nonce and a temporary public/private keypair and sends a handshake packet back
with this just generated information and with the cookie field being the Other with this just generated information and with the cookie field being the Other
Cookie contained in the received handshake. Cookie contained in the received handshake.
Both then use these temporary keys to generate the session key with which every Both then use these temporary keys to generate the session key, with which every
data packet sent and received will be encrypted and decrypted. The nonce sent data packet sent and received will be encrypted and decrypted. The nonce sent
in the handshake will be used to encrypt the first data packet sent, the nonce in the handshake will be used to encrypt the first data packet sent, the nonce
+ 1 the second, the nonce + 2 the third and so on. + 1 for the second, the nonce + 2 for the third, and so on.
Data packets: Data packets:
@ -109,12 +109,12 @@ data ids:
packet request packet: [uint8_t (1)][uint8_t num][uint8_t num][uint8_t packet request packet: [uint8_t (1)][uint8_t num][uint8_t num][uint8_t
num]...[uint8_t num] num]...[uint8_t num]
the list of nums are a list of packet numbers the other is requesting. The list of nums are a list of packet numbers the other is requesting.
to get the real packet numbers from this list take the recvbuffers buffer_start In order to get the real packet numbers from this list, take the recvbuffers buffer_start
from the packet, subtract 1 to it and put it in packet_num then start from the from the packet, subtract 1 from it and put it in packet_num, then start from the
beginning of the num list: if num is zero, add 255 to packet_num then do the beginning of the num list: if num is zero, add 255 to packet_num, then do the
next num. if num isn't zero, add its value to packet_num, note that the other next num. If num isn't zero, add its value to packet_num, note that the other
has requested we send this packet again to them then continue to the next num in has requested we send this packet again to them, then continue to the next num in
the list. the list.