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protover: Fix memleak in Rust implementation.
* FIXES #25127: https://bugs.torproject.org/25127.
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changes/bug25127
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changes/bug25127
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@ -0,0 +1,7 @@
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o Minor bugfixes (Rust FFI):
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- Fix a minor memory leak which would happen whenever the C code would call
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the Rust implementation of protover_get_supported_protocols(). This was
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due to the C version returning a static string, whereas the Rust version
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newly allocated a CString to pass accross the FFI boundary. Consequently,
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the C code was not expecting to need to free() what it was given. Fixes
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bug 25127; bugfix on 0.3.2.1-alpha.
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@ -137,18 +137,25 @@ pub extern "C" fn protocol_list_supports_protocol_or_later(
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/// Provide an interface for C to translate arguments and return types for
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/// protover::get_supported_protocols
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#[no_mangle]
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pub extern "C" fn protover_get_supported_protocols() -> *mut c_char {
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// Not handling errors when unwrapping as the content is controlled
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// and is an empty string
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let empty = CString::new("").unwrap();
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pub extern "C" fn protover_get_supported_protocols() -> *const c_char {
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let supported: &'static CStr;
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let supported = get_supported_protocols();
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let c_supported = match CString::new(supported) {
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Ok(n) => n,
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Err(_) => return empty.into_raw(),
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};
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// If we're going to pass it to C, there cannot be any intermediate NUL
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// bytes. An assert is okay here, since changing the const byte slice
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// in protover.rs to contain a NUL byte somewhere in the middle would be a
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// programming error.
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assert!(!SUPPORTED_PROTOCOLS[..SUPPORTED_PROTOCOLS.len() - 1].contains(&0x00));
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assert!(SUPPORTED_PROTOCOLS[SUPPORTED_PROTOCOLS.len() - 1] == 0x00);
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c_supported.into_raw()
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// It's okay to call the "unchecked" version of the function because
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// we can see that the bytes we're passing into it 1) are valid UTF-8,
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// 2) have no intermediate NUL bytes, and 3) are terminated with a NUL
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// byte.
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unsafe {
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supported = CStr::from_bytes_with_nul_unchecked(SUPPORTED_PROTOCOLS);
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}
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supported.as_ptr()
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}
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/// Provide an interface for C to translate arguments and return types for
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@ -3,12 +3,14 @@
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use external::c_tor_version_as_new_as;
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use std::str;
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use std::str::FromStr;
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use std::fmt;
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use std::collections::{HashMap, HashSet};
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use std::ops::Range;
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use std::string::String;
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/// The first version of Tor that included "proto" entries in its descriptors.
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/// Authorities should use this to decide whether to guess proto lines.
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///
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@ -22,21 +24,29 @@ const FIRST_TOR_VERSION_TO_ADVERTISE_PROTOCOLS: &'static str = "0.2.9.3-alpha";
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/// C_RUST_COUPLED: src/or/protover.c `MAX_PROTOCOLS_TO_EXPAND`
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const MAX_PROTOCOLS_TO_EXPAND: u32 = 500;
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/// Currently supported protocols and their versions
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/// Currently supported protocols and their versions, as a byte-slice.
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///
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/// # Warning
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///
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/// This byte-slice ends in a NUL byte. This is so that we can directly convert
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/// it to an `&'static CStr` in the FFI code, in order to hand the static string
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/// to C in a way that is compatible with C static strings.
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///
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/// Rust code which wishes to accesses this string should use
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/// `protover::get_supported_protocols()` instead.
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///
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/// C_RUST_COUPLED: src/or/protover.c `protover_get_supported_protocols`
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const SUPPORTED_PROTOCOLS: &'static [&'static str] = &[
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"Cons=1-2",
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"Desc=1-2",
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"DirCache=1-2",
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"HSDir=1-2",
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"HSIntro=3-4",
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"HSRend=1-2",
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"Link=1-5",
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"LinkAuth=1,3",
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"Microdesc=1-2",
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"Relay=1-2",
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];
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pub(crate) const SUPPORTED_PROTOCOLS: &'static [u8] =
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b"Cons=1-2 \
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Desc=1-2 \
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DirCache=1-2 \
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HSDir=1-2 \
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HSIntro=3-4 \
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HSRend=1-2 \
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Link=1-5 \
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LinkAuth=1,3 \
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Microdesc=1-2 \
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Relay=1-2\0";
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/// Known subprotocols in Tor. Indicates which subprotocol a relay supports.
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///
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@ -94,8 +104,11 @@ impl FromStr for Proto {
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///
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/// "HSDir=1-1 LinkAuth=1"
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///
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pub fn get_supported_protocols() -> String {
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SUPPORTED_PROTOCOLS.join(" ")
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pub fn get_supported_protocols() -> &'static str {
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unsafe {
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// The `len() - 1` is to remove the NUL byte.
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str::from_utf8_unchecked(&SUPPORTED_PROTOCOLS[..SUPPORTED_PROTOCOLS.len() - 1])
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}
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}
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/// Translates a vector representation of a protocol list into a HashMap
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@ -134,7 +147,7 @@ fn parse_protocols_from_string<'a>(
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/// of the error.
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///
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fn tor_supported() -> Result<HashMap<Proto, HashSet<u32>>, &'static str> {
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parse_protocols(SUPPORTED_PROTOCOLS.iter())
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parse_protocols(get_supported_protocols().split(" "))
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}
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/// Get the unique version numbers supported by a subprotocol.
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@ -625,7 +638,7 @@ pub fn compute_vote(
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}
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let mut final_output: HashMap<String, String> =
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HashMap::with_capacity(SUPPORTED_PROTOCOLS.len());
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HashMap::with_capacity(get_supported_protocols().split(" ").count());
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// Go through and remove verstions that are less than the threshold
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for (protocol, versions) in all_count {
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