Backport the TC_HANDLE parser to main.

Replace C code with native Rust, including unit tests to find the
edge-cases.

src/rust/Cargo.lock

@@ -1327,7 +1327,6 @@ name = "lqos_bus"
 version = "0.1.0"
 dependencies = [
  "bincode",
- "cc",
  "criterion",
  "log",
  "lqos_config",

src/rust/lqos_bus/Cargo.toml

@@ -17,9 +17,6 @@ tokio = { version = "1", features = [ "rt", "macros", "net", "io-util", "time" ]
 log = "0"
 nix = "0"
 
-[build-dependencies]
-cc = "1.0"
-
 [dev-dependencies]
 criterion = { version = "0", features = [ "html_reports", "async_tokio"] }
 

src/rust/lqos_bus/build.rs

@@ -1,3 +0,0 @@
-fn main() {
-  cc::Build::new().file("src/tc_handle_parser.c").compile("tc_handle_parse.o");
-}

src/rust/lqos_bus/src/tc_handle.rs

@@ -1,6 +1,6 @@
 use log::error;
+use lqos_utils::hex_string::read_hex_string;
 use serde::{Deserialize, Serialize};
-use std::ffi::CString;
 use thiserror::Error;
 
 /// Provides consistent handling of TC handle types.
@@ -9,20 +9,9 @@ use thiserror::Error;
 )]
 pub struct TcHandle(u32);
 
-#[allow(non_camel_case_types)]
-type __u32 = ::std::os::raw::c_uint;
-#[allow(dead_code)]
 const TC_H_ROOT: u32 = 4294967295;
-#[allow(dead_code)]
 const TC_H_UNSPEC: u32 = 0;
 
-extern "C" {
-  pub fn get_tc_classid(
-    h: *mut __u32,
-    str_: *const ::std::os::raw::c_char,
-  ) -> ::std::os::raw::c_int;
-}
-
 impl TcHandle {
   /// Returns the TC handle as two values, indicating major and minor
   /// TC handle values.
@@ -36,23 +25,26 @@ impl TcHandle {
   /// Build a TC handle from a string. This is actually a complicated
   /// operation, since it has to handle "root" and other strings as well
   /// as simple "1:2" mappings. Calls a C function to handle this gracefully.
-  pub fn from_string<S: ToString>(
-    handle: S,
+  pub fn from_string(
+    handle: &str,
   ) -> Result<Self, TcHandleParseError> {
-    let mut tc_handle: __u32 = 0;
-    let str = CString::new(handle.to_string());
-    if str.is_err() {
-      error!("Unable to convert {} to a C-String.", handle.to_string());
-      return Err(TcHandleParseError::CString);
-    }
-    let str = str.unwrap();
-    let handle_pointer: *mut __u32 = &mut tc_handle;
-    let result = unsafe { get_tc_classid(handle_pointer, str.as_ptr()) };
-    if result != 0 {
-      error!("Unable to parse {} as a valid TC handle", handle.to_string());
-      Err(TcHandleParseError::InvalidInput)
-    } else {
-      Ok(Self(tc_handle))
+    let handle = handle.trim();
+    match handle {
+      "root" => Ok(Self(TC_H_ROOT)),
+      "none" => Ok(Self(TC_H_UNSPEC)),
+      _ => {
+        if !handle.contains(':') {
+          error!("Unable to parse TC handle {handle}. Must contain a colon.");
+          return Err(TcHandleParseError::InvalidInput(handle.to_string()));
+        }
+        let parts: Vec<&str> = handle.split(':').collect();        
+        let major = read_hex_string(parts[0]).map_err(|_| TcHandleParseError::InvalidInput(handle.to_string()))?;
+        let minor = read_hex_string(parts[1]).map_err(|_| TcHandleParseError::InvalidInput(handle.to_string()))?;
+        if major >= (1<<16) || minor >= (1<<16) {
+          return Err(TcHandleParseError::InvalidInput(handle.to_string()));
+        }
+        Ok(Self((major << 16) | minor))
+      }
     }
   }
 
@@ -86,7 +78,7 @@ pub enum TcHandleParseError {
   )]
   CString,
   #[error("Invalid input")]
-  InvalidInput,
+  InvalidInput(String),
 }
 
 #[cfg(test)]
@@ -151,4 +143,10 @@ mod test {
       }
     }
   }
+
+  #[test]
+  fn blank_minor() {
+    let tc = TcHandle::from_string("7FFF:").unwrap();
+    assert_eq!(tc.to_string().to_uppercase(), "7FFF:0");
+  }
 }

src/rust/lqos_bus/src/tc_handle_parser.c

@@ -1,46 +0,0 @@
-// Imported from https://github.com/thebracket/cpumap-pping/blob/master/src/xdp_iphash_to_cpu_cmdline.c
-// Because it uses strtoul and is based on the TC source, including it directly
-// seemed like the path of least resistance.
-
-#include <stdlib.h>
-#include <stdbool.h>
-#include <string.h>
-#include <linux/types.h>
-#include <linux/pkt_sched.h> /* TC macros */
-
-/* Handle classid parsing based on iproute source */
-int get_tc_classid(__u32 *h, const char *str)
-{
-	__u32 major, minor;
-	char *p;
-
-	major = TC_H_ROOT;
-	if (strcmp(str, "root") == 0)
-		goto ok;
-	major = TC_H_UNSPEC;
-	if (strcmp(str, "none") == 0)
-		goto ok;
-	major = strtoul(str, &p, 16);
-	if (p == str) {
-		major = 0;
-		if (*p != ':')
-			return -1;
-	}
-	if (*p == ':') {
-		if (major >= (1<<16))
-			return -1;
-		major <<= 16;
-		str = p+1;
-		minor = strtoul(str, &p, 16);
-		if (*p != 0)
-			return -1;
-		if (minor >= (1<<16))
-			return -1;
-		major |= minor;
-	} else if (*p != 0)
-		return -1;
-
-ok:
-	*h = major;
-	return 0;
-}

src/rust/lqos_utils/src/hex_string.rs

@@ -19,6 +19,9 @@ use thiserror::Error;
 /// assert_eq!(read_hex_string("0x12AD").unwrap(), 4781);
 /// ```
 pub fn read_hex_string(s: &str) -> Result<u32, HexParseError> {
+  if s.is_empty() {
+    return Ok(0);
+  }
   let result = u32::from_str_radix(&s.replace("0x", ""), 16);
   match result {
     Ok(data) => Ok(data),