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prop339: Unify the address format into one object

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Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit is contained in:
David Goulet 2022-06-07 09:47:07 -04:00
parent 16d536e9ff
commit e787831689
1 changed files with 38 additions and 27 deletions
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65
proposals/339-udp-over-tor.md
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@ -149,6 +149,39 @@ along with extensions to some older relay message types. We note in
passing how we could extend these messages to support unconnected UDP
sockets in the future.
### Common Format
We define here a common format for an "address" that is used both in a
CONNECT_UDP and CONNECTED_UDP cell.
#### Address
Defines an IP or Hostname address along with its port. This can be seen as the
`ADDRPORT` of a `BEGIN` cell defined in tor-spec.txt but with a different
format.
```
/* Address types */
const T_HOSTNAME = 0x01;
const T_IPV4 = 0x04;
const T_IPV6 = 0x06;
struct address {
u8 type IN [T_IPV4, T_IPV6, T_HOSTNAME];
u8 len IN [0, 255];
union addr[type] with length len {
T_IPV4: u32 ipv4;
T_IPV6: u8 ipv6[16];
T_HOSTNAME: u8 hostname[];
};
u16 port IN [1, 65535];
}
```
The `hostname` follows the RFC1035 for its accepted length that is 63
characters or less that is a `len` between 0 and 255 (bytes). It should
contain a sequence of nonzero octets as in any nul byte results in a malformed
cell.
### CONNECT_UDP
@ -161,26 +194,13 @@ sockets in the future.
struct connect_udp_body {
/* As in BEGIN cells. */
u32 flags;
/* Tag for union below. */
u8 addr_type IN [T_HOSTNAME, T_IPV4, T_IPV6];
/* Length of the following union */
u8 addr_len;
/* The address to connect to. */
union address[addr_type] with length addr_len {
T_IPV4: u32 ipv4;
T_IPV6: u8 ipv6[16];
T_HOSTNAME: hostname;
};
u16 port;
/* Address to connect to. */
struct address addr;
// The rest is ignored.
// TODO: Is "the rest is ignored" still a good idea? Look at Rochet's
// research.
}
/* Address types */
const T_HOSTNAME = 0x01;
const T_IPV4 = 0x04;
const T_IPV6 = 0x06;
/* As in BEGIN cells: these control how hostnames are interpreted.
Clients MUST NOT send unrecognized flags; relays MUST ignore them.
@ -212,20 +232,11 @@ struct udp_connected_body {
// TODO: Is "the rest is ignored" still a good idea? Look at Rochet's
// research.
}
/* Note that this is a subset of the allowable address parts of a CONNECT_UDP
* message */
struct address {
u8 tag IN [T_IPV4, T_IPV6];
u8 len;
union addr[tag] with length len {
T_IPV4: u32 ipv4;
T_IPV6: u8 ipv6[16];
};
u16 port;
}
```
Both `our_address` and `their_address` MUST NOT be of type `T_HOSTNAME` else
the cell is considered malformed.
### DATAGRAM
```