paddle::verify_signature(): Extract signature from params

Make it easier on users by not requiring them to pass a signature into
the method. This means they don't have to extract the `p_signature`
param and base64 decode it themselves.

Essentially, we want to move the code from `request` that removes the
`p_signature` key and base64 decodes it into the
`paddle::verify_signature()` function.

We need to make the string-like type params in `verify_signature()`
conform additionally to `PartialEq<str>` and `PartialOrd`. Doing so
allows us to find the key "p_signature".

To remove the `p_signature` param from the iterator, we partition it
into two iterators: one for the `p_signature` entry, and another for the
rest. We then extract the value of `p_signature` and base64 decode it
for verification.

Add a new error type in case no `p_signature` entry is found in the
iterator.

3 files changed, 2 insertions, 14 deletions

diff --git a/license-generator/src/errors.rs b/license-generator/src/errors.rs
index e21edd4..0799c3e 100644
--- a/license-generator/src/errors.rs
+++ b/license-generator/src/errors.rs
@@ -1,4 +1,3 @@
-use base64;
 use log;
 use mysql;
 use paddle;
@@ -8,7 +7,6 @@ error_chain! {
         EnvVar(::std::env::VarError);
         Io(::std::io::Error);
 
-        Base64(base64::DecodeError);
         Log(log::SetLoggerError);
         MySql(mysql::error::Error);
 
diff --git a/license-generator/src/lib.rs b/license-generator/src/lib.rs
index e2c02b6..bf3ed57 100644
--- a/license-generator/src/lib.rs
+++ b/license-generator/src/lib.rs
@@ -1,5 +1,3 @@
-extern crate base64;
-
 #[macro_use]
 extern crate error_chain;
 extern crate log;
diff --git a/license-generator/src/request.rs b/license-generator/src/request.rs
index 325fdec..190a756 100644
--- a/license-generator/src/request.rs
+++ b/license-generator/src/request.rs
@@ -1,19 +1,11 @@
-use base64;
 use paddle;
 
 use errors::*;
 use params;
 
 pub fn verified(req_params: &str) -> Result<bool> {
-    let mut p = params::parse(&req_params);
-    let signature = p.remove("p_signature");
+    let p = params::parse(&req_params);
     let pem = include_bytes!("../private/paddle.pubkey.asc");
 
-    match signature {
-        Some(signature) => {
-            let signature = base64::decode(signature.as_bytes())?;
-            Ok(paddle::verify_signature(pem, &signature, p)?)
-        },
-        None => Ok(false),
-    }
+    Ok(paddle::verify_signature(pem, p)?)
 }