Implement draft /auth API

book/src/api-vc-auth-header.md

@@ -6,13 +6,13 @@ The validator client HTTP server requires that all requests have the following
 HTTP header:
 
 - Name: `Authorization`
-- Value: `Basic <api-token>`
+- Value: `Bearer <api-token>`
 
 Where `<api-token>` is a string that can be obtained from the validator client
 host. Here is an example `Authorization` header:
 
 ```
-Authorization Basic api-token-0x03eace4c98e8f77477bb99efb74f9af10d800bd3318f92c33b719a4644254d4123
+Authorization: Bearer api-token-0x03eace4c98e8f77477bb99efb74f9af10d800bd3318f92c33b719a4644254d4123
 ```
 
 ## Obtaining the API token
@@ -35,12 +35,27 @@ to the file containing the api token.
 Sep 28 19:17:52.615 INFO HTTP API started                        api_token_file: "$HOME/prater/validators/api-token.txt", listen_address: 127.0.0.1:5062
 ```
 
+The _path_ to the API token may also be fetched from the HTTP API itself (this endpoint is the only
+one accessible without the token):
+
+```bash
+curl http://localhost:5062/eth/v1/auth
+```
+
+Response:
+
+```json
+{
+    "token_path": "/home/karlm/.lighthouse/prater/validators/api-token.txt"
+}
+```
+
 ## Example
 
 Here is an example `curl` command using the API token in the `Authorization` header:
 
 ```bash
-curl localhost:5062/lighthouse/version -H "Authorization: Basic api-token-0x03eace4c98e8f77477bb99efb74f9af10d800bd3318f92c33b719a4644254d4123"
+curl localhost:5062/lighthouse/version -H "Authorization: Bearer api-token-0x03eace4c98e8f77477bb99efb74f9af10d800bd3318f92c33b719a4644254d4123"
 ```
 
 The server should respond with its version:

common/eth2/src/lib.rs

@@ -24,6 +24,7 @@ use serde::{de::DeserializeOwned, Serialize};
 use std::convert::TryFrom;
 use std::fmt;
 use std::iter::Iterator;
+use std::path::PathBuf;
 use std::time::Duration;
 
 pub const V1: EndpointVersion = EndpointVersion(1);
@@ -53,6 +54,12 @@ pub enum Error {
     InvalidServerSentEvent(String),
     /// The server returned an invalid SSZ response.
     InvalidSsz(ssz::DecodeError),
+    /// An I/O error occurred while loading an API token from disk.
+    TokenReadError(PathBuf, std::io::Error),
+    /// The client has been configured without a server pubkey, but requires one for this request.
+    NoServerPubkey,
+    /// The client has been configured without an API token, but requires one for this request.
+    NoToken,
 }
 
 impl Error {
@@ -70,6 +77,8 @@ impl Error {
             Error::InvalidJson(_) => None,
             Error::InvalidServerSentEvent(_) => None,
             Error::InvalidSsz(_) => None,
+            Error::TokenReadError(..) => None,
+            Error::NoServerPubkey | Error::NoToken => None,
         }
     }
 }
@@ -80,6 +89,12 @@ impl fmt::Display for Error {
     }
 }
 
+impl From<reqwest::Error> for Error {
+    fn from(error: reqwest::Error) -> Self {
+        Error::Reqwest(error)
+    }
+}
+
 /// A struct to define a variety of different timeouts for different validator tasks to ensure
 /// proper fallback behaviour.
 #[derive(Clone)]