1 files changed, 268 insertions, 0 deletions
diff --git a/third_party/rust/origin-trial-token/lib.rs b/third_party/rust/origin-trial-token/lib.rs
new file mode 100644
index 0000000000..8872095a1d
--- /dev/null
+++ b/third_party/rust/origin-trial-token/lib.rs
@@ -0,0 +1,268 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//! Implements a simple processor for
+//! https://github.com/chromium/chromium/blob/d7da0240cae77824d1eda25745c4022757499131/third_party/blink/public/common/origin_trials/origin_trials_token_structure.md
+//!
+//! This crate intentionally leaves the cryptography to the caller. See the
+//! tools/ directory for example usages.
+
+
+/// Latest version as documented.
+pub const LATEST_VERSION: u8 = 3;
+
+#[repr(C)]
+pub struct RawToken {
+    version: u8,
+    signature: [u8; 64],
+    payload_length: [u8; 4],
+    /// Payload is an slice of payload_length bytes, and has to be verified
+    /// before returning it to the caller.
+    payload: [u8; 0],
+}
+
+#[derive(Debug)]
+pub enum TokenValidationError {
+    BufferTooSmall,
+    MismatchedPayloadSize { expected: usize, actual: usize },
+    InvalidSignature,
+    UnknownVersion,
+    UnsupportedThirdPartyToken,
+    UnexpectedUsageInNonThirdPartyToken,
+    MalformedPayload(serde_json::Error),
+}
+
+impl RawToken {
+    const HEADER_SIZE: usize = std::mem::size_of::<Self>();
+
+    #[inline]
+    pub fn version(&self) -> u8 {
+        self.version
+    }
+
+    #[inline]
+    pub fn signature(&self) -> &[u8; 64] {
+        &self.signature
+    }
+
+    #[inline]
+    pub fn payload_length(&self) -> usize {
+        u32::from_be_bytes(self.payload_length) as usize
+    }
+
+    #[inline]
+    pub fn as_buffer(&self) -> &[u8] {
+        let buffer_size = Self::HEADER_SIZE + self.payload_length();
+        unsafe { std::slice::from_raw_parts(self as *const _ as *const u8, buffer_size) }
+    }
+
+    #[inline]
+    pub fn payload(&self) -> &[u8] {
+        let len = self.payload_length();
+        unsafe { std::slice::from_raw_parts(self.payload.as_ptr(), len) }
+    }
+
+    /// Returns a RawToken from a raw buffer.
+    pub fn from_buffer<'a>(buffer: &'a [u8]) -> Result<&'a Self, TokenValidationError> {
+        if buffer.len() <= Self::HEADER_SIZE {
+            return Err(TokenValidationError::BufferTooSmall);
+        }
+        assert_eq!(
+            std::mem::align_of::<Self>(),
+            1,
+            "RawToken is a view over the buffer"
+        );
+        let raw_token = unsafe { &*(buffer.as_ptr() as *const Self) };
+        let payload = &buffer[Self::HEADER_SIZE..];
+        let expected = raw_token.payload_length();
+        let actual = payload.len();
+        if expected != actual {
+            return Err(TokenValidationError::MismatchedPayloadSize { expected, actual });
+        }
+        Ok(raw_token)
+    }
+
+    /// The data to verify the signature in this raw token.
+    fn signature_data(&self) -> Vec<u8> {
+        Self::raw_signature_data(self.version, self.payload())
+    }
+
+    /// The data to sign or verify given a payload and a version.
+    fn raw_signature_data(version: u8, payload: &[u8]) -> Vec<u8> {
+        let mut data = Vec::with_capacity(payload.len() + 5);
+        data.push(version);
+        data.extend((payload.len() as u32).to_be_bytes());
+        data.extend(payload);
+        data
+    }
+
+    /// Verify the signature of this raw token.
+    pub fn verify(&self, verify_signature: impl FnOnce(&[u8; 64], &[u8]) -> bool) -> bool {
+        let signature_data = self.signature_data();
+        verify_signature(&self.signature, &signature_data)
+    }
+}
+
+#[derive(serde::Deserialize, serde::Serialize, Debug, Eq, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub enum Usage {
+    #[serde(rename = "")]
+    None,
+    Subset,
+}
+
+impl Usage {
+    fn is_none(&self) -> bool {
+        *self == Self::None
+    }
+}
+
+impl Default for Usage {
+    fn default() -> Self {
+        Self::None
+    }
+}
+
+fn is_false(t: &bool) -> bool {
+    *t == false
+}
+
+/// An already decoded and maybe-verified token.
+#[derive(serde::Deserialize, serde::Serialize, Debug, Eq, PartialEq)]
+#[serde(rename_all = "camelCase")]
+pub struct Token {
+    pub origin: String,
+    pub feature: String,
+    pub expiry: u64, // Timestamp. Seconds since epoch.
+    #[serde(default, skip_serializing_if = "is_false")]
+    pub is_subdomain: bool,
+    #[serde(default, skip_serializing_if = "is_false")]
+    pub is_third_party: bool,
+    #[serde(default, skip_serializing_if = "Usage::is_none")]
+    pub usage: Usage,
+}
+
+impl Token {
+    #[inline]
+    pub fn origin(&self) -> &str {
+        &self.origin
+    }
+
+    #[inline]
+    pub fn feature(&self) -> &str {
+        &self.feature
+    }
+
+    #[inline]
+    pub fn expiry_since_unix_epoch(&self) -> std::time::Duration {
+        std::time::Duration::from_secs(self.expiry)
+    }
+
+    #[inline]
+    pub fn expiry_time(&self) -> Option<std::time::SystemTime> {
+        std::time::UNIX_EPOCH.checked_add(self.expiry_since_unix_epoch())
+    }
+
+    #[inline]
+    pub fn is_expired(&self) -> bool {
+        let now_duration = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .expect("System time before epoch?");
+        now_duration >= self.expiry_since_unix_epoch()
+    }
+
+    /// Most high-level function: For a given buffer, tries to parse it and
+    /// verify it as a token.
+    pub fn from_buffer(
+        buffer: &[u8],
+        verify_signature: impl FnOnce(&[u8; 64], &[u8]) -> bool,
+    ) -> Result<Self, TokenValidationError> {
+        Self::from_raw_token(RawToken::from_buffer(buffer)?, verify_signature)
+    }
+
+    /// Validates a RawToken's signature and converts the token if valid.
+    pub fn from_raw_token(
+        token: &RawToken,
+        verify_signature: impl FnOnce(&[u8; 64], &[u8]) -> bool,
+    ) -> Result<Self, TokenValidationError> {
+        if !token.verify(verify_signature) {
+            return Err(TokenValidationError::InvalidSignature);
+        }
+        Self::from_raw_token_unverified(token)
+    }
+
+    /// Converts the token from a raw token, without verifying first.
+    pub fn from_raw_token_unverified(token: &RawToken) -> Result<Self, TokenValidationError> {
+        Self::from_payload(token.version, token.payload())
+    }
+
+    /// Converts the token from a raw payload, version pair.
+    pub fn from_payload(version: u8, payload: &[u8]) -> Result<Self, TokenValidationError> {
+        if version != 2 && version != 3 {
+            assert_ne!(version, LATEST_VERSION);
+            return Err(TokenValidationError::UnknownVersion);
+        }
+
+        let token: Token = match serde_json::from_slice(payload) {
+            Ok(t) => t,
+            Err(e) => return Err(TokenValidationError::MalformedPayload(e)),
+        };
+
+        // Third-party tokens are not supported in version 2.
+        if token.is_third_party {
+            if version == 2 {
+                return Err(TokenValidationError::UnsupportedThirdPartyToken);
+            }
+        } else if !token.usage.is_none() {
+            return Err(TokenValidationError::UnexpectedUsageInNonThirdPartyToken);
+        }
+
+        Ok(token)
+    }
+
+    /// Converts the token to a raw payload.
+    pub fn to_payload(&self) -> Vec<u8> {
+        serde_json::to_string(self)
+            .expect("Should always be able to turn a token into a payload")
+            .into_bytes()
+    }
+
+    /// Converts the token to the data that should be signed.
+    pub fn to_signature_data(&self) -> Vec<u8> {
+        RawToken::raw_signature_data(LATEST_VERSION, &self.to_payload())
+    }
+
+    /// Turns the token into a fully signed token.
+    pub fn to_signed_token(&self, sign: impl FnOnce(&[u8]) -> [u8; 64]) -> Vec<u8> {
+        self.to_signed_token_with_payload(sign, &self.to_payload())
+    }
+
+    /// DO NOT EXPOSE: This is intended for testing only. We need to test with
+    /// the original payload so that the tokens match, but we assert
+    /// that self.to_payload() and payload are equivalent.
+    fn to_signed_token_with_payload(
+        &self,
+        sign: impl FnOnce(&[u8]) -> [u8; 64],
+        payload: &[u8],
+    ) -> Vec<u8> {
+        let signature_data_with_payload = RawToken::raw_signature_data(LATEST_VERSION, &payload);
+        let signature = sign(&signature_data_with_payload);
+
+        let mut buffer = Vec::with_capacity(1 + signature.len() + 4 + payload.len());
+        buffer.push(LATEST_VERSION);
+        buffer.extend(signature);
+        buffer.extend((payload.len() as u32).to_be_bytes());
+        buffer.extend(payload);
+
+        if cfg!(debug_assertions) {
+            let token = Self::from_buffer(&buffer, |_, _| true).expect("Creating malformed token?");
+            assert_eq!(self, &token, "Token differs after deserialization?");
+        }
+
+        buffer
+    }
+}
+
+#[cfg(test)]
+mod tests;