mastersrv: Add config file and hot-reloading of it

This allows to add bans and port forward exceptions without restarting
the mastersrv itself.

It also allows reloading the locations database (with the important
caveat that it is mmap-ed, and as such must be removed before being
overridden in the file system).

src/mastersrv/Cargo.toml

@@ -9,6 +9,7 @@ license = "Zlib"
 [workspace]
 
 [dependencies]
+arc-swap = "1.7.1"
 arrayvec = { version = "0.5.2", features = ["serde"] }
 base64 = "0.13.0"
 bytes = "1.1.0"
@@ -19,6 +20,7 @@ clap = { version = "2.34.0", default-features = false, features = [
 env_logger = "0.8.3"
 headers = "0.3.7"
 hex = "0.4.3"
+ipnet = "2.9.0"
 libloc = "0.1.0"
 log = "0.4.17"
 mime = "0.3.16"
@@ -30,7 +32,13 @@ serde_json = { version = "1.0.64", features = [
   "raw_value",
 ] }
 sha2 = "0.10.0"
-tokio = { version = "1.6.0", features = ["macros", "rt", "rt-multi-thread"] }
+toml = "0.8.19"
+tokio = { version = "1.6.0", features = [
+  "macros",
+  "rt",
+  "rt-multi-thread",
+  "signal",
+] }
 tokio-stream = { version = "0.1.8", features = ["net"] }
 url = { version = "2.2.2", features = ["serde"] }
 warp = { version = "0.3.1", default-features = false }

src/mastersrv/src/locations.rs

@@ -1,4 +1,5 @@
 use arrayvec::ArrayString;
+use std::fmt;
 use std::net::IpAddr;
 use std::path::Path;
 
@@ -8,22 +9,22 @@ pub type Location = ArrayString<[u8; 12]>;
 #[derive(Debug)]
 pub struct LocationsError(String);
 
+#[derive(Default)]
 pub struct Locations {
     inner: Option<libloc::Locations>,
 }
 
-impl Locations {
-    pub fn empty() -> Locations {
-        Locations {
-            inner: None,
-        }
+impl fmt::Display for LocationsError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.0.fmt(f)
     }
+}
+
+impl Locations {
     pub fn read(filename: &Path) -> Result<Locations, LocationsError> {
         let inner = libloc::Locations::open(filename)
             .map_err(|e| LocationsError(format!("error opening {:?}: {}", filename, e)))?;
-        Ok(Locations {
-            inner: Some(inner),
-        })
+        Ok(Locations { inner: Some(inner) })
     }
     pub fn lookup(&self, addr: IpAddr) -> Option<Location> {
         self.inner.as_ref().and_then(|inner| {