5 ms·

Rewrite Tor in Rust

94 points by Jonhoo 10y ago

axman6 10y ago
As a side note, Galois have written an implementation of Tor which happily interacts with official tor, for use in HalVM based unikernels. So, if you want ephemeral tor nodes, HalVM is a pretty great way to get it working. Edit: Video about it [2] [1] https://github.com/GaloisInc/haskell-tor https://github.com/GaloisInc/haskell-tor [2] https://www.youtube.com/watch?v=oHcHTFleNtg https://www.youtube.com/watch?v=oHcHTFleNtg
erlend_sh 10y ago
The discussion is 10 months old and never went anywhere. What makes this relevant now?
kibwen 10y ago
The OP is likely nothing more than wishful thinking, but I can see why people are intrigued by the prospect. An important thing to note is that it's entirely possible to perform a slow, gradual integration of Rust code into a C/C++ codebase (such as Mozilla is doing with Firefox), but only if your codebase is sufficiently modular with well-defined interfaces for Rust-based libs to slot into. If all you've got is a big ball of mud, then your first step is to work on the modularization of your codebase (which, IMO, has a good chance of increasing your code quality regardless of whether you eventually decide to introduce any Rust).
- MichaelGG 10y ago
  Since Rust and C can agree on ABI and memory layout issues, you can move the code over function-by-function if you were so inclined, right? Declare the structs in the headers and auto-gen the Rust versions (is there a tool for the inverse?).
  - comex 10y ago
    You can, but idiomatic Rust code looks pretty different from idiomatic C code - to give a concrete example, int get_a_string(char **out) // returns error code could be translated literally as fn get_a_string(out: *mut *mut c_char) -> c_int but much preferable would be fn get_a_string() -> Result<String, Errcode> [where Result and String are standard library types; Errcode would be a custom enum.] I suppose you could go from the first to the second incrementally, then refactor to the third. But I'm not sure it'd work well.
    - randommodnar 10y ago
      Is there a solution yet in Rust to this problem of, monadic-ish constructs like Result and Option, but no nice way to chain them together without hideous nesting, like Haskell's "do" or Scala's "for"?
      - steveklabnik 10y ago
        We don't have HKT and therefore we can't have real do notation. The mdo crate provides a duck-typed macro. .and_then calls themselves aren't too bad, with the right whitespace.
      - comex 10y ago
        In the special case of Result, the new ? operator is going to subsume try! and offer more flexibility: https://github.com/rust-lang/rfcs/pull/243 https://github.com/rust-lang/rfcs/pull/243 (note that what was actually accepted differs from the text of the RFC, you need to scroll to the bottom) As steveklabnik says, there's nothing resembling generalized monadic do notation for now.
  - kibwen 10y ago
    This presumes that functions are well-defined boundaries in your C codebase, which may not be true if one is leaning heavily on global state.
- alexnewman 10y ago
  You end up having to toss a layer of c around your c++ last time I checked. Does c++ even have an abi yet?
  - roblabla 10y ago
    well, not a standard one. That's what extern "C" is for : if you want a standardized API, C always had one.
    - deleted 10y ago
      [deleted]
    - gpderetta 10y ago
      Neither C nor C++ have a standardized ABI, if by standardized you mean part of their respective ISO standard. Nor they could, as the many of ABI properties (names, calling conventions, layout, object and executable file format) are intimately platform (as in OS and CPU) specific. Most platform officially specify their C ABI, and many also specify their C++ ABI (usually in therm of the C one). Itanium C++ ABI (plus the platform specific psABIs) has become the de facto C++ ABI for many unix and unix-like platforms.
  - Manishearth 10y ago
    You can call into Rust directly from C++ (with a header file). But yeah, the reverse requires a C layer. rust-bindgen has experimental C++ support which we use for spidermonkey but it isn't perfect.
    - sitkack 10y ago
      > You can call into Rust directly from C++ (with a header file). Can you tell me more about this?
      - steveklabnik 10y ago
        This is C and I tossed it together VERY quickly but $ cat hello.rs #[no_mangle] pub extern fn plus_one(x: isize) -> isize { x + 1 } $ cat hello.c #include<stdio.h> extern int plus_one(int); int main() { int result = plus_one(5); printf("result is %d\n", result); return 0; } $ rustc hello.rs --crate-type=dylib $ gcc hello.c -lhello -L . $ LD_LIBRARY_PATH=. ./a.out result is 6
- voiper1 10y ago
  >If all you've got is a big ball of mud, then your first step is to work on the modularization of your codebase (which, IMO, has a good chance of increasing your code quality regardless of whether you eventually decide to introduce any Rust). I wanted to up-vote that bit.
CoconutPilot 10y ago
Is there an anti-pattern for this kind of thing? Its a two line bug report suggesting years of development effort. There is a huge multiplication factor between the time invested by the bug reporter and the time required to do what he asks.
- alexnewman 10y ago
  Only if your goal is to doom the existing tor project. Lots of great research projects start this way. Often times it influences the main project or merges.
  - ycombinatorMan 10y ago
    what good would come of this, to be honest?
roywiggins 10y ago
It would be a bit embarrassing to rewrite in Rust and then have the network penetrated because they screwed up the crypto during the rewrite...
WizardlySquid 10y ago
Rewrite %s in whatever the newest hipster language is.

94 points by Jonhoo 10y ago

As a side note, Galois have written an implementation of Tor which happily interacts with official tor, for use in HalVM based unikernels. So, if you want ephemeral tor nodes, HalVM is a pretty great way to get it working. Edit: Video about it [2] [1] https://github.com/GaloisInc/haskell-tor https://github.com/GaloisInc/haskell-tor [2] https://www.youtube.com/watch?v=oHcHTFleNtg https://www.youtube.com/watch?v=oHcHTFleNtg

erlend_sh 10y ago

The discussion is 10 months old and never went anywhere. What makes this relevant now?

kibwen 10y ago

The OP is likely nothing more than wishful thinking, but I can see why people are intrigued by the prospect. An important thing to note is that it's entirely possible to perform a slow, gradual integration of Rust code into a C/C++ codebase (such as Mozilla is doing with Firefox), but only if your codebase is sufficiently modular with well-defined interfaces for Rust-based libs to slot into. If all you've got is a big ball of mud, then your first step is to work on the modularization of your codebase (which, IMO, has a good chance of increasing your code quality regardless of whether you eventually decide to introduce any Rust).

MichaelGG 10y ago
Since Rust and C can agree on ABI and memory layout issues, you can move the code over function-by-function if you were so inclined, right? Declare the structs in the headers and auto-gen the Rust versions (is there a tool for the inverse?).
- comex 10y ago
  You can, but idiomatic Rust code looks pretty different from idiomatic C code - to give a concrete example, int get_a_string(char **out) // returns error code could be translated literally as fn get_a_string(out: *mut *mut c_char) -> c_int but much preferable would be fn get_a_string() -> Result<String, Errcode> [where Result and String are standard library types; Errcode would be a custom enum.] I suppose you could go from the first to the second incrementally, then refactor to the third. But I'm not sure it'd work well.
  - randommodnar 10y ago
    Is there a solution yet in Rust to this problem of, monadic-ish constructs like Result and Option, but no nice way to chain them together without hideous nesting, like Haskell's "do" or Scala's "for"?
    - steveklabnik 10y ago
      We don't have HKT and therefore we can't have real do notation. The mdo crate provides a duck-typed macro. .and_then calls themselves aren't too bad, with the right whitespace.
    - comex 10y ago
      In the special case of Result, the new ? operator is going to subsume try! and offer more flexibility: https://github.com/rust-lang/rfcs/pull/243 https://github.com/rust-lang/rfcs/pull/243 (note that what was actually accepted differs from the text of the RFC, you need to scroll to the bottom) As steveklabnik says, there's nothing resembling generalized monadic do notation for now.
- kibwen 10y ago
  This presumes that functions are well-defined boundaries in your C codebase, which may not be true if one is leaning heavily on global state.
alexnewman 10y ago
You end up having to toss a layer of c around your c++ last time I checked. Does c++ even have an abi yet?
- roblabla 10y ago
  well, not a standard one. That's what extern "C" is for : if you want a standardized API, C always had one.
  - deleted 10y ago
    [deleted]
  - gpderetta 10y ago
    Neither C nor C++ have a standardized ABI, if by standardized you mean part of their respective ISO standard. Nor they could, as the many of ABI properties (names, calling conventions, layout, object and executable file format) are intimately platform (as in OS and CPU) specific. Most platform officially specify their C ABI, and many also specify their C++ ABI (usually in therm of the C one). Itanium C++ ABI (plus the platform specific psABIs) has become the de facto C++ ABI for many unix and unix-like platforms.
- Manishearth 10y ago
  You can call into Rust directly from C++ (with a header file). But yeah, the reverse requires a C layer. rust-bindgen has experimental C++ support which we use for spidermonkey but it isn't perfect.
  - sitkack 10y ago
    > You can call into Rust directly from C++ (with a header file). Can you tell me more about this?
    - steveklabnik 10y ago
      This is C and I tossed it together VERY quickly but $ cat hello.rs #[no_mangle] pub extern fn plus_one(x: isize) -> isize { x + 1 } $ cat hello.c #include<stdio.h> extern int plus_one(int); int main() { int result = plus_one(5); printf("result is %d\n", result); return 0; } $ rustc hello.rs --crate-type=dylib $ gcc hello.c -lhello -L . $ LD_LIBRARY_PATH=. ./a.out result is 6
voiper1 10y ago
>If all you've got is a big ball of mud, then your first step is to work on the modularization of your codebase (which, IMO, has a good chance of increasing your code quality regardless of whether you eventually decide to introduce any Rust). I wanted to up-vote that bit.

CoconutPilot 10y ago

Is there an anti-pattern for this kind of thing? Its a two line bug report suggesting years of development effort. There is a huge multiplication factor between the time invested by the bug reporter and the time required to do what he asks.

alexnewman 10y ago
Only if your goal is to doom the existing tor project. Lots of great research projects start this way. Often times it influences the main project or merges.
- ycombinatorMan 10y ago
  what good would come of this, to be honest?

roywiggins 10y ago

It would be a bit embarrassing to rewrite in Rust and then have the network penetrated because they screwed up the crypto during the rewrite...

WizardlySquid 10y ago

Rewrite %s in whatever the newest hipster language is.