api: allow auth delegation

1 files changed, 27 insertions, 5 deletions

diff --git a/src/config/mod.rs b/src/config/mod.rs
index c7f96a3..37c010e 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -100,14 +100,28 @@ pub(crate) const OPTIONS: &[OptionSpec] = &[
         Kind::Text,
         "PATH",
         None,
-        "Users of the HTTP API (htpasswd file with Argon2 hashes). Required, but with relay-only (then without it, no HTTP API).",
+        "Users of the HTTP API (htpasswd file with Argon2 hashes). Required, but with user-header or relay-only (then without either, no HTTP API).",
+    ),
+    option(
+        "user-header",
+        Kind::Text,
+        "NAME",
+        None,
+        "A request header naming the user, set by a reverse proxy in front of the HTTP API that authenticated the request itself (e.g. X-Remote-User, from nginx's $remote_user). Believed only from trusted-proxies; other requests need htpasswd's basic authentication. The proxy must set or clear it on every request.",
+    ),
+    option(
+        "trusted-proxies",
+        Kind::List,
+        "ADDRESS,[ADDRESS...]",
+        Some("127.0.0.1,::1"),
+        "Addresses (an IP address, or a range as ADDRESS/BITS) of the reverse proxies whose user-header is believed.",
     ),
     option(
         "protocol-writers",
         Kind::List,
         "USER,[USER...]",
         None,
-        "HTTP API users (from htpasswd) who may write protocol data under /store/_continuum (remake records, members, forget records), e.g. to repair a stuck remake. Such writes act on the whole swarm and are logged. Epoch metadata and the swarm ID are never writable.",
+        "HTTP API users (from htpasswd or user-header) who may write protocol data under /store/_continuum (remake records, members, forget records), e.g. to repair a stuck remake. Such writes act on the whole swarm and are logged. Epoch metadata and the swarm ID are never writable.",
     ),
     option(
         "log-format",
@@ -482,8 +496,11 @@ pub(crate) fn spec(name: &str) -> Option<&'static OptionSpec> {
 pub(crate) struct Settings {
     #[serde(default = "default_bind_addr")]
     pub(crate) bind_addr: SocketAddr,
-    /// Required (`check`), but with `relay_only`.
+    /// Required (`check`), but with `user_header` or `relay_only`.
     pub(crate) htpasswd: Option<String>,
+    pub(crate) user_header: Option<String>,
+    #[serde(default = "default_trusted_proxies")]
+    pub(crate) trusted_proxies: Vec<String>,
     #[serde(default)]
     pub(crate) protocol_writers: Vec<String>,
     #[serde(default)]
@@ -621,6 +638,9 @@ pub(crate) struct Settings {
 fn default_bind_addr() -> SocketAddr {
     SocketAddr::from(([127, 0, 0, 1], 3000))
 }
+fn default_trusted_proxies() -> Vec<String> {
+    vec!["127.0.0.1".to_owned(), "::1".to_owned()]
+}
 fn default_document_append() -> Duration {
     Duration::from_secs(5)
 }
@@ -696,8 +716,10 @@ impl Settings {
         if self.relay_only {
             self.check_relay_only()?;
         } else {
-            if self.htpasswd.is_none() {
-                bail!("htpasswd is required: the users of the HTTP API");
+            if self.htpasswd.is_none() && self.user_header.is_none() {
+                bail!(
+                    "htpasswd is required: the users of the HTTP API (or user-header, with a reverse proxy that authenticates them)"
+                );
             }
             if self.node_key_file.is_none() {
                 bail!(