Remove RFC2047 decoder (#967)

## Summary

- This was inherited from
d719988323/src/metadata.rs (LL78C2-L91C26)
- ...which introduced this code here:
9cd1d43f7c
- ...with the originating issue here:
https://github.com/PyO3/maturin/issues/612
- ...and the upstream issue here:
https://github.com/staktrace/mailparse/issues/50

It seems like the goal was to support Unicode in certain header fields,
but I don't think this is necessary for us. We only use
`get_first_value` for `Requires-Python`, which has to be ASCII, doesn't
it?

In my testing, it seems like the `charset` hack can also be removed. The
tests I copied over actually work without it, which makes me a bit
skeptical.

The main benefit here is that we get to a remove a _big_ dependency
stack, including Chumsky and Stacker and psm which have limited
cross-platform support.

Cargo.lock

@@ -26,18 +26,6 @@ dependencies = [
  "const-random",
 ]
 
-[[package]]
-name = "ahash"
-version = "0.8.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "77c3a9648d43b9cd48db467b3f87fdd6e146bcc88ab0180006cef2179fe11d01"
-dependencies = [
- "cfg-if 1.0.0",
- "once_cell",
- "version_check",
- "zerocopy",
-]
-
 [[package]]
 name = "aho-corasick"
 version = "1.1.2"
@@ -62,12 +50,6 @@ dependencies = [
  "alloc-no-stdlib",
 ]
 
-[[package]]
-name = "allocator-api2"
-version = "0.2.16"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0942ffc6dcaadf03badf6e6a2d0228460359d5e34b57ccdc720b7382dfbd5ec5"
-
 [[package]]
 name = "android-tzdata"
 version = "0.1.1"
@@ -480,16 +462,6 @@ dependencies = [
  "windows-targets 0.48.5",
 ]
 
-[[package]]
-name = "chumsky"
-version = "0.9.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8eebd66744a15ded14960ab4ccdbfb51ad3b81f51f3f04a80adac98c985396c9"
-dependencies = [
- "hashbrown 0.14.3",
- "stacker",
-]
-
 [[package]]
 name = "ciborium"
 version = "0.2.1"
@@ -747,7 +719,7 @@ version = "3.11.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0f260e2fc850179ef410018660006951c1b55b79e8087e87111a2c388994b9b5"
 dependencies = [
- "ahash 0.3.8",
+ "ahash",
  "cfg-if 0.1.10",
  "num_cpus",
 ]
@@ -1233,10 +1205,6 @@ name = "hashbrown"
 version = "0.14.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "290f1a1d9242c78d09ce40a5e87e7554ee637af1351968159f4952f028f75604"
-dependencies = [
- "ahash 0.8.7",
- "allocator-api2",
-]
 
 [[package]]
 name = "heck"
@@ -2272,15 +2240,6 @@ dependencies = [
  "unicode-ident",
 ]
 
-[[package]]
-name = "psm"
-version = "0.1.21"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5787f7cda34e3033a72192c018bc5883100330f362ef279a8cbccfce8bb4e874"
-dependencies = [
- "cc",
-]
-
 [[package]]
 name = "pubgrub"
 version = "0.2.1"
@@ -2842,7 +2801,6 @@ dependencies = [
  "pep508_rs",
  "puffin-normalize",
  "regex",
- "rfc2047-decoder",
  "serde",
  "serde_json",
  "tempfile",
@@ -3139,20 +3097,6 @@ dependencies = [
  "rand",
 ]
 
-[[package]]
-name = "rfc2047-decoder"
-version = "1.0.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9e372613f15fc5171f9052b0c1fbafca5b1e5b0ba86aa13c9c39fd91ca1f7955"
-dependencies = [
- "base64 0.21.7",
- "charset",
- "chumsky",
- "memchr",
- "quoted_printable",
- "thiserror",
-]
-
 [[package]]
 name = "ring"
 version = "0.17.7"
@@ -3438,19 +3382,6 @@ version = "0.9.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
 
-[[package]]
-name = "stacker"
-version = "0.1.15"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c886bd4480155fd3ef527d45e9ac8dd7118a898a46530b7b94c3e21866259fce"
-dependencies = [
- "cc",
- "cfg-if 1.0.0",
- "libc",
- "psm",
- "winapi",
-]
-
 [[package]]
 name = "strsim"
 version = "0.10.0"
@@ -4506,26 +4437,6 @@ dependencies = [
  "linked-hash-map",
 ]
 
-[[package]]
-name = "zerocopy"
-version = "0.7.32"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "74d4d3961e53fa4c9a25a8637fc2bfaf2595b3d3ae34875568a5cf64787716be"
-dependencies = [
- "zerocopy-derive",
-]
-
-[[package]]
-name = "zerocopy-derive"
-version = "0.7.32"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9ce1b18ccd8e73a9321186f97e46f9f04b778851177567b1975109d26a08d2a6"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.48",
-]
-
 [[package]]
 name = "zip"
 version = "0.6.6"

Cargo.toml

@@ -67,7 +67,6 @@ regex = { version = "1.10.2" }
 reqwest = { version = "0.11.23", default-features = false, features = ["json", "gzip", "brotli", "stream", "rustls-tls"] }
 reqwest-middleware = { version = "0.2.4" }
 reqwest-retry = { version = "0.3.0" }
-rfc2047-decoder = { version = "1.0.2" }
 rmp-serde = { version = "1.1.2" }
 rustc-hash = { version = "1.1.0" }
 seahash = { version = "4.1.0" }

crates/pypi-types/Cargo.toml

@@ -21,7 +21,6 @@ chrono = { workspace = true, features = ["serde"] }
 mailparse = { workspace = true }
 once_cell = { workspace = true }
 regex = { workspace = true }
-rfc2047-decoder = { workspace = true }
 serde = { workspace = true }
 thiserror = { workspace = true }
 tracing = { workspace = true }

crates/pypi-types/src/metadata.rs

@@ -75,24 +75,16 @@ pub enum Error {
 impl Metadata21 {
     /// Parse distribution metadata from metadata bytes
     pub fn parse(content: &[u8]) -> Result<Self, Error> {
-        // HACK: trick mailparse to parse as UTF-8 instead of ASCII
+        let msg = mailparse::parse_mail(content)?;
-        let mut mail = b"Content-Type: text/plain; charset=utf-8\n".to_vec();
-        mail.extend_from_slice(content);
-
-        let msg = mailparse::parse_mail(&mail)?;
         let headers = msg.get_headers();
 
         let get_first_value = |name| {
             headers.get_first_header(name).and_then(|header| {
-                match rfc2047_decoder::decode(header.get_value_raw()) {
+                let value = header.get_value();
-                    Ok(value) => {
+                if value == "UNKNOWN" {
-                        if value == "UNKNOWN" {
+                    None
-                            None
+                } else {
-                        } else {
+                    Some(value)
-                            Some(value)
-                        }
-                    }
-                    Err(_) => None,
                 }
             })
         };
@@ -141,3 +133,55 @@ impl Metadata21 {
         })
     }
 }
+
+impl FromStr for Metadata21 {
+    type Err = Error;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Metadata21::parse(s.as_bytes())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::str::FromStr;
+
+    use pep440_rs::Version;
+    use puffin_normalize::PackageName;
+
+    use crate::Error;
+
+    use super::Metadata21;
+
+    #[test]
+    fn test_parse_from_str() {
+        let s = "Metadata-Version: 1.0";
+        let meta: Result<Metadata21, Error> = s.parse();
+        assert!(matches!(meta, Err(Error::FieldNotFound("Name"))));
+
+        let s = "Metadata-Version: 1.0\nName: asdf";
+        let meta = Metadata21::parse(s.as_bytes());
+        assert!(matches!(meta, Err(Error::FieldNotFound("Version"))));
+
+        let s = "Metadata-Version: 1.0\nName: asdf\nVersion: 1.0";
+        let meta = Metadata21::parse(s.as_bytes()).unwrap();
+        assert_eq!(meta.metadata_version, "1.0");
+        assert_eq!(meta.name, PackageName::from_str("asdf").unwrap());
+        assert_eq!(meta.version, Version::new([1, 0]));
+
+        let s = "Metadata-Version: 1.0\nName: asdf\nVersion: 1.0\nAuthor: 中文\n\n一个 Python 包";
+        let meta = Metadata21::parse(s.as_bytes()).unwrap();
+        assert_eq!(meta.metadata_version, "1.0");
+        assert_eq!(meta.name, PackageName::from_str("asdf").unwrap());
+        assert_eq!(meta.version, Version::new([1, 0]));
+
+        let s = "Metadata-Version: 1.0\nName: =?utf-8?q?foobar?=\nVersion: 1.0";
+        let meta = Metadata21::parse(s.as_bytes()).unwrap();
+        assert_eq!(meta.metadata_version, "1.0");
+        assert_eq!(meta.name, PackageName::from_str("foobar").unwrap());
+        assert_eq!(meta.version, Version::new([1, 0]));
+
+        let s = "Metadata-Version: 1.0\nName: =?utf-8?q?=C3=A4_space?= <x@y.org>\nVersion: 1.0";
+        let meta = Metadata21::parse(s.as_bytes());
+        assert!(matches!(meta, Err(Error::InvalidName(_))));
+    }
+}