On Thu, Jul 5, 2018 at 7:47 PM, Nick Mathewson <ni...@torproject.org> wrote:
> Hello, friends!
Oh no! I hit send too early. More info follows below.
> For quite a while now, the program "tor" has been built from source
> code in just two directories: src/common and src/or.
>
> This has become more-or-less untenable, for a few reasons -- most
> notably of which is that it has led our code to become more
> spaghetti-ish than I can endorse with a clean conscience.
>
> So to fix that, we've gone and done a huge code movement in our git
> master branch, which will land in a release once Tor 0.3.5.1-alpha is
> out.
>
> Here's what we did:
>
> * src/common has been turned into a set of static libraries. These
> all live in the "src/lib/*" directories. The dependencies between
> these libraries should have no cycles. The libraries are:
>
> arch -- Headers to handle architectural differences
> cc -- headers to handle differences among compilers
> compress -- wraps zlib, zstd, lzma
> container -- high-level container types
> crypt_ops -- Cryptographic operations. Planning to split this into
> a higher and lower level library
> ctime -- Operations that need to run in constant-time. (Properly,
> data-invariant time)
> defs -- miscelaneous definitions needed throughout Tor.
> encoding -- transforming one data type into another, and various
> data types into strings.
> err -- lowest-level error handling, in cases where we can't use
> the logs because something that the logging system needs has broken.
> evloop -- Generic event-loop handling logic
> fdio -- Low-level IO wrapper functions for file descriptors.
> fs -- Operations on the filesystem
> intmath -- low-level integer math and misc bit-twiddling hacks
> lock -- low-level locking code
> log -- Tor's logging module. This library sits roughly halfway up
> the library dependency diagram, since everything it depends on has to
> be carefully crafted to *not* log.
> malloc -- Low-level wrappers for the platform memory allocation functions.
> math -- Higher-level mathematical functions, and floating-point math
> memarea -- An arena allocator
> meminfo -- Functions for querying the current process's memory
> status and resources
> net -- Networking compatibility and convenience code
> osinfo -- Querying information about the operating system
> process -- Launching and querying the status of other processes
> sandbox -- Backend for the linux seccomp2 sandbox
> smartlist_core -- The lowest-level of the smartlist_t data type.
> Separated from the rest of the containers library because the logging
> subsystem depends on it.
> string -- Compatibility and convenience functions for manipulating
> C strings.
> term -- Terminal-related functions (currently limited to a getpass
> function).
> testsupport -- Macros for mocking, unit tests, etc.
> thread -- Higher-level thread compatibility code
> time -- Higher-level time management code, including format
> conversions and monotonic time
> tls -- Our wrapper around our TLS library
> trace -- Formerly src/trace -- a generic event tracing API
> wallclock -- Low-level time code, used by the log module.
>
> * To ensure that the dependency graph in src/common remains under
> control, there is a tool that you can run called "make
> check-includes". It verifies that each module in Tor only includes
> the headers that it is permitted to include, using a per-directory
> ".may_include" file.
>
> * The src/or/or.h header has been split into numerous smaller
> headers. Notably, many important structures are now declared in a
> header called foo_st.h, where "foo" is the name of the structure.
>
> * The src/or directory, which had most of Tor's code, had been split
> up into several directories. This is still a work in progress: This
> code has not itself been refactored, and its dependency graph is still
> a tangled web. I hope we'll be working on that over the coming
> releases, but it will take a while to do.
>
> The new top-level source directories are:
>
> src/core -- Code necessary to actually perform or use onion routing.
> src/feature -- Code used only by some onion routing
> configurations, or only for a special purpose.
> src/app -- Top-level code to run, invoke, and configure the
> lower-level code
>
> The new second-level source directories are:
> src/core/crypto -- High-level cryptographic protocols used in Tor
> src/core/mainloop -- Tor's event loop, connection-handling, and
> traffic-routing code.
> src/core/or -- Parts related to handling onion routing itself
> src/core/proto -- Support for encoding
src/core/proto -- support for encoding and decoding different
wire protocols
src/feature/api -- Support for making Tor embeddable
src/feature/client -- Functionality which only Tor clients need
src/feature/control -- Controller implementation
src/feature/dirauth -- Directory authority
src/feature/dircache -- Directory cache
src/feature/dirclient -- Directory client
src/feature/dircommon -- Shared code between the other directory modules
src/feature/hibernate -- Hibernating when Tor is out of bandwidth
or shutting down
src/feature/hs -- v3 onion service implementation
src/feature/hs_common -- shared code between both onion service
implementations
src/feature/nodelist -- storing and accessing the list of relays on
the network.
src/feature/relay -- code that only relay servers and exit servers need.
src/feature/rend -- v2 onion service implementation
src/feature/stats -- statistics and history
src/app/config -- configuration and state for Tor
src/app/main -- Top-level functions to invoke the rest or Tor.
>
> * The "tor" executable is now built in src/app/tor rather than src/or/tor.
>
> * There are more static libraries than before that you need to build
> into your application if you want to embed Tor. Rather than
> maintaining this list yourself, I recommend that you run "make
> show-libs" to have Tor emit a list of what you need to link.
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