First version of admin API (#298)

**Spec:**

- [x] Start writing
- [x] Specify all layout endpoints
- [x] Specify all endpoints for operations on keys
- [x] Specify all endpoints for operations on key/bucket permissions
- [x] Specify all endpoints for operations on buckets
- [x] Specify all endpoints for operations on bucket aliases

View rendered spec at <https://git.deuxfleurs.fr/Deuxfleurs/garage/src/branch/admin-api/doc/drafts/admin-api.md>

**Code:**

- [x] Refactor code for admin api to use common api code that was created for K2V

**General endpoints:**

- [x] Metrics
- [x] GetClusterStatus
- [x] ConnectClusterNodes
- [x] GetClusterLayout
- [x] UpdateClusterLayout
- [x] ApplyClusterLayout
- [x] RevertClusterLayout

**Key-related endpoints:**

- [x] ListKeys
- [x] CreateKey
- [x] ImportKey
- [x] GetKeyInfo
- [x] UpdateKey
- [x] DeleteKey

**Bucket-related endpoints:**

- [x] ListBuckets
- [x] CreateBucket
- [x] GetBucketInfo
- [x] DeleteBucket
- [x] PutBucketWebsite
- [x] DeleteBucketWebsite

**Operations on key/bucket permissions:**

- [x] BucketAllowKey
- [x] BucketDenyKey

**Operations on bucket aliases:**

- [x] GlobalAliasBucket
- [x] GlobalUnaliasBucket
- [x] LocalAliasBucket
- [x] LocalUnaliasBucket

**And also:**

- [x] Separate error type for the admin API (this PR includes a quite big refactoring of error handling)
- [x] Add management of website access
- [ ] Check that nothing is missing wrt what can be done using the CLI
- [ ] Improve formatting of the spec
- [x] Make sure everyone is cool with the API design

Fix #231
Fix #295

Co-authored-by: Alex Auvolat <alex@adnab.me>
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/298
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>

4 files changed, 55 insertions, 16 deletions

diff --git a/src/api/signature/error.rs b/src/api/signature/error.rs
new file mode 100644
index 00000000..f5a067bd
--- /dev/null
+++ b/src/api/signature/error.rs
@@ -0,0 +1,36 @@
+use err_derive::Error;
+
+use crate::common_error::CommonError;
+pub use crate::common_error::{CommonErrorDerivative, OkOrBadRequest, OkOrInternalError};
+
+/// Errors of this crate
+#[derive(Debug, Error)]
+pub enum Error {
+	#[error(display = "{}", _0)]
+	/// Error from common error
+	Common(CommonError),
+
+	/// Authorization Header Malformed
+	#[error(display = "Authorization header malformed, expected scope: {}", _0)]
+	AuthorizationHeaderMalformed(String),
+
+	// Category: bad request
+	/// The request contained an invalid UTF-8 sequence in its path or in other parameters
+	#[error(display = "Invalid UTF-8: {}", _0)]
+	InvalidUtf8Str(#[error(source)] std::str::Utf8Error),
+
+	/// The client sent a header with invalid value
+	#[error(display = "Invalid header value: {}", _0)]
+	InvalidHeader(#[error(source)] hyper::header::ToStrError),
+}
+
+impl<T> From<T> for Error
+where
+	CommonError: From<T>,
+{
+	fn from(err: T) -> Self {
+		Error::Common(CommonError::from(err))
+	}
+}
+
+impl CommonErrorDerivative for Error {}
diff --git a/src/api/signature/mod.rs b/src/api/signature/mod.rs
index 5646f4fa..dd5b590c 100644
--- a/src/api/signature/mod.rs
+++ b/src/api/signature/mod.rs
@@ -4,11 +4,12 @@ use sha2::Sha256;
 
 use garage_util::data::{sha256sum, Hash};
 
-use crate::error::*;
-
+pub mod error;
 pub mod payload;
 pub mod streaming;
 
+use error::*;
+
 pub const SHORT_DATE: &str = "%Y%m%d";
 pub const LONG_DATETIME: &str = "%Y%m%dT%H%M%SZ";
 
@@ -16,7 +17,7 @@ type HmacSha256 = Hmac<Sha256>;
 
 pub fn verify_signed_content(expected_sha256: Hash, body: &[u8]) -> Result<(), Error> {
 	if expected_sha256 != sha256sum(body) {
-		return Err(Error::BadRequest(
+		return Err(Error::bad_request(
 			"Request content hash does not match signed hash".to_string(),
 		));
 	}
diff --git a/src/api/signature/payload.rs b/src/api/signature/payload.rs
index 9137dd2d..4c7934e5 100644
--- a/src/api/signature/payload.rs
+++ b/src/api/signature/payload.rs
@@ -15,7 +15,7 @@ use super::LONG_DATETIME;
 use super::{compute_scope, signing_hmac};
 
 use crate::encoding::uri_encode;
-use crate::error::*;
+use crate::signature::error::*;
 
 pub async fn check_payload_signature(
 	garage: &Garage,
@@ -105,7 +105,7 @@ fn parse_authorization(
 	let (auth_kind, rest) = authorization.split_at(first_space);
 
 	if auth_kind != "AWS4-HMAC-SHA256" {
-		return Err(Error::BadRequest("Unsupported authorization method".into()));
+		return Err(Error::bad_request("Unsupported authorization method"));
 	}
 
 	let mut auth_params = HashMap::new();
@@ -129,10 +129,11 @@ fn parse_authorization(
 	let date = headers
 		.get("x-amz-date")
 		.ok_or_bad_request("Missing X-Amz-Date field")
+		.map_err(Error::from)
 		.and_then(|d| parse_date(d))?;
 
 	if Utc::now() - date > Duration::hours(24) {
-		return Err(Error::BadRequest("Date is too old".to_string()));
+		return Err(Error::bad_request("Date is too old".to_string()));
 	}
 
 	let auth = Authorization {
@@ -156,7 +157,7 @@ fn parse_query_authorization(
 	headers: &HashMap<String, String>,
 ) -> Result<Authorization, Error> {
 	if algorithm != "AWS4-HMAC-SHA256" {
-		return Err(Error::BadRequest(
+		return Err(Error::bad_request(
 			"Unsupported authorization method".to_string(),
 		));
 	}
@@ -179,10 +180,10 @@ fn parse_query_authorization(
 		.get("x-amz-expires")
 		.ok_or_bad_request("X-Amz-Expires not found in query parameters")?
 		.parse()
-		.map_err(|_| Error::BadRequest("X-Amz-Expires is not a number".to_string()))?;
+		.map_err(|_| Error::bad_request("X-Amz-Expires is not a number".to_string()))?;
 
 	if duration > 7 * 24 * 3600 {
-		return Err(Error::BadRequest(
+		return Err(Error::bad_request(
 			"X-Amz-Exprires may not exceed a week".to_string(),
 		));
 	}
@@ -190,10 +191,11 @@ fn parse_query_authorization(
 	let date = headers
 		.get("x-amz-date")
 		.ok_or_bad_request("Missing X-Amz-Date field")
+		.map_err(Error::from)
 		.and_then(|d| parse_date(d))?;
 
 	if Utc::now() - date > Duration::seconds(duration) {
-		return Err(Error::BadRequest("Date is too old".to_string()));
+		return Err(Error::bad_request("Date is too old".to_string()));
 	}
 
 	Ok(Authorization {
@@ -301,7 +303,7 @@ pub async fn verify_v4(
 		.get(&EmptyKey, &key_id)
 		.await?
 		.filter(|k| !k.state.is_deleted())
-		.ok_or_else(|| Error::Forbidden(format!("No such key: {}", &key_id)))?;
+		.ok_or_else(|| Error::forbidden(format!("No such key: {}", &key_id)))?;
 	let key_p = key.params().unwrap();
 
 	let mut hmac = signing_hmac(
@@ -314,7 +316,7 @@ pub async fn verify_v4(
 	hmac.update(payload);
 	let our_signature = hex::encode(hmac.finalize().into_bytes());
 	if signature != our_signature {
-		return Err(Error::Forbidden("Invalid signature".to_string()));
+		return Err(Error::forbidden("Invalid signature".to_string()));
 	}
 
 	Ok(key)
diff --git a/src/api/signature/streaming.rs b/src/api/signature/streaming.rs
index ded9d993..c8358c4f 100644
--- a/src/api/signature/streaming.rs
+++ b/src/api/signature/streaming.rs
@@ -12,7 +12,7 @@ use garage_util::data::Hash;
 
 use super::{compute_scope, sha256sum, HmacSha256, LONG_DATETIME};
 
-use crate::error::*;
+use crate::signature::error::*;
 
 pub fn parse_streaming_body(
 	api_key: &Key,
@@ -87,7 +87,7 @@ fn compute_streaming_payload_signature(
 	let mut hmac = signing_hmac.clone();
 	hmac.update(string_to_sign.as_bytes());
 
-	Hash::try_from(&hmac.finalize().into_bytes()).ok_or_internal_error("Invalid signature")
+	Ok(Hash::try_from(&hmac.finalize().into_bytes()).ok_or_internal_error("Invalid signature")?)
 }
 
 mod payload {
@@ -163,10 +163,10 @@ impl From<SignedPayloadStreamError> for Error {
 		match err {
 			SignedPayloadStreamError::Stream(e) => e,
 			SignedPayloadStreamError::InvalidSignature => {
-				Error::BadRequest("Invalid payload signature".into())
+				Error::bad_request("Invalid payload signature")
 			}
 			SignedPayloadStreamError::Message(e) => {
-				Error::BadRequest(format!("Chunk format error: {}", e))
+				Error::bad_request(format!("Chunk format error: {}", e))
 			}
 		}
 	}