macros: sanitize/validate metric name (#95)

* macros: sanitize metric name

* bump msrv for tests

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        rust_version: ['1.42.0', 'stable', 'nightly']
+        rust_version: ['1.43.0', 'stable', 'nightly']
         os: [ubuntu-latest, windows-latest, macOS-latest]
     steps:
     - uses: actions/checkout@v1

metrics-macros/Cargo.toml

@@ -23,3 +23,5 @@ syn = "1.0"
 quote = "1.0"
 proc-macro2 = "1.0"
 proc-macro-hack = "0.5"
+lazy_static = "1.4"
+regex = "1.3"

metrics-macros/src/lib.rs

@@ -2,8 +2,11 @@ extern crate proc_macro;
 
 use self::proc_macro::TokenStream;
 
+use lazy_static::lazy_static;
+use proc_macro2::Span;
 use proc_macro_hack::proc_macro_hack;
 use quote::{format_ident, quote, ToTokens};
+use regex::Regex;
 use syn::parse::{Error, Parse, ParseStream, Result};
 use syn::{parse_macro_input, Expr, LitStr, Token};
 
@@ -15,6 +18,15 @@ enum Key {
     Scoped(LitStr),
 }
 
+impl Key {
+    pub fn span(&self) -> Span {
+        match self {
+            Key::Scoped(s) => s.span(),
+            Key::NotScoped(s) => s.span(),
+        }
+    }
+}
+
 enum Labels {
     Existing(Expr),
     Inline(Vec<(LitStr, Expr)>),
@@ -262,14 +274,31 @@ fn can_use_fast_path(labels: &Option<Labels>) -> bool {
 }
 
 fn read_key(input: &mut ParseStream) -> Result<Key> {
-    if let Ok(_) = input.parse::<Token![<]>() {
+    let key = if let Ok(_) = input.parse::<Token![<]>() {
         let s = input.parse::<LitStr>()?;
         input.parse::<Token![>]>()?;
-        Ok(Key::Scoped(s))
+        Key::Scoped(s)
     } else {
         let s = input.parse::<LitStr>()?;
-        Ok(Key::NotScoped(s))
+        Key::NotScoped(s)
+    };
+
+    let inner = match key {
+        Key::Scoped(ref s) => s.value(),
+        Key::NotScoped(ref s) => s.value(),
+    };
+
+    lazy_static! {
+        static ref RE: Regex = Regex::new("^[a-zA-Z_:\\.][a-zA-Z0-9_:\\.]*$").unwrap();
     }
+    if !RE.is_match(&inner) {
+        return Err(Error::new(
+            key.span(),
+            "metric name must match ^[a-zA-Z_:.][a-zA-Z0-9_:.]*$",
+        ));
+    }
+
+    Ok(key)
 }
 
 fn quote_key_name(key: Key) -> proc_macro2::TokenStream {

metrics/tests/macros.rs

@@ -0,0 +1,6 @@
+#[test]
+pub fn macros() {
+    let t = trybuild::TestCases::new();
+    t.pass("tests/macros/01_trailing_comma.rs");
+    t.compile_fail("tests/macros/02_metric_name.rs");
+}

metrics/tests/macros/02_metric_name.rs

@@ -0,0 +1,11 @@
+use metrics::counter;
+
+fn valid_name() {
+    counter!("abc_def", 1);
+}
+
+fn invalid_name() {
+    counter!("abc$def");
+}
+
+fn main() {}

metrics/tests/macros/02_metric_name.stderr

@@ -0,0 +1,7 @@
+error: metric name must match ^[a-zA-Z_:.][a-zA-Z0-9_:.]*$
+ --> $DIR/02_metric_name.rs:8:14
+  |
+8 |     counter!("abc$def");
+  |              ^^^^^^^^^
+  |
+  = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

metrics/tests/macros_parsing.rs

@@ -1,5 +0,0 @@
-#[test]
-pub fn parsing() {
-    let t = trybuild::TestCases::new();
-    t.pass("tests/macros_parsing/*.rs");
-}