Fix bug where digest was required even for GET requests

Rouille returns `Some(empty body)` for GET requests, rather than the `None` we
were expecting, so allow the digest to be omitted when the body is present but
empty.

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "http-sig"
 description = "Implementation of the IETF draft 'Signing HTTP Messages'"
-version = "0.3.0"
+version = "0.3.1"
 authors = ["Jack Cargill <jack@passfort.com>", "Diggory Blake"]
 edition = "2018"
 readme = "README.md"

README.md

@@ -21,15 +21,18 @@ features.
 | [reqwest](https://crates.io/crates/reqwest)       | Client        | Supports blocking and non-blocking requests.<sup>1</sup>      |
 | [rouille](https://crates.io/crates/rouille)       | Server        |                                                               |
 
-1. Due to limitations of the reqwest API, digests can only be calculated automatically for non-blocking non-streaming requests. For
-   blocking or streaming requests, the user must add the digest manually before signing the request, or else the `Digest` header will
-   not be included in the signature.
+1. Due to limitations of the reqwest API, digests cannot be calculated automatically for non-blocking, streaming requests. For
+   these requests, the user must add the digest manually before signing the request, or else the `Digest` header will
+   not be included in the signature. Automatic digests for streaming requests *are* supported via the blocking API.
 
 ### Supported signature algorithms:
 
 Algorithm registry: https://tools.ietf.org/id/draft-cavage-http-signatures-12.html#hsa-registry
 
 - `hmac-sha256`
+- `hmac-sha512`
+- `rsa-sha256`
+- `rsa-sha512`
 
 ### Supported digest algorithms:
 

src/rouille_impls.rs

@@ -58,6 +58,8 @@ impl<'a> ServerRequestLike for &'a rouille::Request {
             let mut result = Vec::new();
             if let Err(e) = body.read_to_end(&mut result) {
                 (None, Some(RouilleBody(RouilleBodyInner::Digested(Err(e)))))
+            } else if result.is_empty() {
+                (None, None)
             } else {
                 let computed_digest = digest.http_digest(&result);
                 (
@@ -87,7 +89,7 @@ mod tests {
     use super::*;
 
     #[test]
-    fn it_works() {
+    fn can_verify_post_request() {
         let key_provider = SimpleKeyProvider::new(vec![(
             "test_key",
             Arc::new(DefaultSignatureAlgorithm::new("abcdefgh".as_bytes()))
@@ -113,4 +115,29 @@ mod tests {
 
         request.verify(&config).unwrap();
     }
+
+    #[test]
+    fn can_verify_get_request() {
+        let key_provider = SimpleKeyProvider::new(vec![(
+            "test_key",
+            Arc::new(DefaultSignatureAlgorithm::new("abcdefgh".as_bytes()))
+                as Arc<dyn HttpSignatureVerify>,
+        )]);
+        let config = VerifyingConfig::new(key_provider).with_validate_date(false);
+
+        let request = rouille::Request::fake_http(
+            "GET",
+            "/foo/bar",
+            vec![
+                ("Date".into(), Utc.ymd(2014, 7, 8)
+                    .and_hms(9, 10, 11)
+                    .format("%a, %d %b %Y %T GMT")
+                    .to_string()),
+                ("Authorization".into(), "Signature keyId=\"test_key\",algorithm=\"hmac-sha256\",signature=\"sGQ3hA9KB40CU1pHbRLXLvLdUWYn+c3fcfL+Sw8kIZE=\",headers=\"(request-target) date".into()),
+            ],
+            Vec::new()
+        );
+
+        request.verify(&config).unwrap();
+    }
 }