notify: add PVE/PBS context

This commit moves PVEContext from `proxmox-perl-rs` into the
`proxmox-notify` crate, since we now also need to access it from
`promxox-mail-forward`. The context is now hidden behind a feature
flag `pve-context`, ensuring that we only compile it when needed.

This commit adds PBSContext, since we now require it for
`proxmox-mail-forward`. Some of the code for PBSContext comes
from `proxmox-mail-forward`.

This commit also changes the global context from being stored in a
`once_cell` to a regular `Mutex`, since we now need to set/reset
the context in `proxmox-mail-forward`.

Signed-off-by: Lukas Wagner <l.wagner@proxmox.com>

proxmox-notify/Cargo.toml

@@ -13,7 +13,6 @@ handlebars = { workspace = true }
 lazy_static.workspace = true
 log.workspace = true
 mail-parser = { workspace = true, optional = true }
-once_cell.workspace = true
 openssl.workspace = true
 proxmox-http = { workspace = true, features = ["client-sync"], optional = true }
 proxmox-http-error.workspace = true
@@ -32,3 +31,5 @@ default = ["sendmail", "gotify"]
 mail-forwarder = ["dep:mail-parser"]
 sendmail = ["dep:proxmox-sys"]
 gotify = ["dep:proxmox-http"]
+pve-context = ["dep:proxmox-sys"]
+pbs-context = ["dep:proxmox-sys"]

proxmox-notify/src/context.rs

@@ -1,21 +0,0 @@
-use std::fmt::Debug;
-
-use once_cell::sync::OnceCell;
-
-pub trait Context: Send + Sync + Debug {
-    fn lookup_email_for_user(&self, user: &str) -> Option<String>;
-    fn default_sendmail_author(&self) -> String;
-    fn default_sendmail_from(&self) -> String;
-    fn http_proxy_config(&self) -> Option<String>;
-}
-
-static CONTEXT: OnceCell<&'static dyn Context> = OnceCell::new();
-
-pub fn set_context(context: &'static dyn Context) {
-    CONTEXT.set(context).expect("context has already been set");
-}
-
-#[allow(unused)] // context is not used if all endpoint features are disabled
-pub(crate) fn context() -> &'static dyn Context {
-    *CONTEXT.get().expect("context has not been yet")
-}

proxmox-notify/src/context/common.rs

@@ -0,0 +1,27 @@
+use std::path::Path;
+
+pub(crate) fn attempt_file_read<P: AsRef<Path>>(path: P) -> Option<String> {
+    match proxmox_sys::fs::file_read_optional_string(path) {
+        Ok(contents) => contents,
+        Err(err) => {
+            log::error!("{err}");
+            None
+        }
+    }
+}
+
+pub(crate) fn lookup_datacenter_config_key(content: &str, key: &str) -> Option<String> {
+    let key_prefix = format!("{key}:");
+    normalize_for_return(
+        content
+            .lines()
+            .find_map(|line| line.strip_prefix(&key_prefix)),
+    )
+}
+
+pub(crate) fn normalize_for_return(s: Option<&str>) -> Option<String> {
+    match s?.trim() {
+        "" => None,
+        s => Some(s.to_string()),
+    }
+}

proxmox-notify/src/context/mod.rs

@@ -0,0 +1,36 @@
+use std::fmt::Debug;
+use std::sync::Mutex;
+
+#[cfg(any(feature = "pve-context", feature = "pbs-context"))]
+pub mod common;
+#[cfg(feature = "pbs-context")]
+pub mod pbs;
+#[cfg(feature = "pve-context")]
+pub mod pve;
+
+/// Product-specific context
+pub trait Context: Send + Sync + Debug {
+    /// Look up a user's email address from users.cfg
+    fn lookup_email_for_user(&self, user: &str) -> Option<String>;
+    /// Default mail author for mail-based targets
+    fn default_sendmail_author(&self) -> String;
+    /// Default from address for sendmail-based targets
+    fn default_sendmail_from(&self) -> String;
+    /// Proxy configuration for the current node
+    fn http_proxy_config(&self) -> Option<String>;
+}
+
+static CONTEXT: Mutex<Option<&'static dyn Context>> = Mutex::new(None);
+
+/// Set the product-specific context
+pub fn set_context(context: &'static dyn Context) {
+    *CONTEXT.lock().unwrap() = Some(context);
+}
+
+/// Get product-specific context.
+///
+/// Panics if the context has not been set yet.
+#[allow(unused)] // context is not used if all endpoint features are disabled
+pub(crate) fn context() -> &'static dyn Context {
+    (*CONTEXT.lock().unwrap()).expect("context for proxmox-notify has not been set yet")
+}

proxmox-notify/src/context/pbs.rs

@@ -0,0 +1,130 @@
+use serde::Deserialize;
+
+use proxmox_schema::{ObjectSchema, Schema, StringSchema};
+use proxmox_section_config::{SectionConfig, SectionConfigPlugin};
+
+use crate::context::{common, Context};
+
+const PBS_USER_CFG_FILENAME: &str = "/etc/proxmox-backup/user.cfg";
+const PBS_NODE_CFG_FILENAME: &str = "/etc/proxmox-backup/node.cfg";
+
+// FIXME: Switch to the actual schema when possible in terms of dependency.
+// It's safe to assume that the config was written with the actual schema restrictions, so parsing
+// it with the less restrictive schema should be enough for the purpose of getting the mail address.
+const DUMMY_ID_SCHEMA: Schema = StringSchema::new("dummy ID").min_length(3).schema();
+const DUMMY_EMAIL_SCHEMA: Schema = StringSchema::new("dummy email").schema();
+const DUMMY_USER_SCHEMA: ObjectSchema = ObjectSchema {
+    description: "minimal PBS user",
+    properties: &[
+        ("userid", false, &DUMMY_ID_SCHEMA),
+        ("email", true, &DUMMY_EMAIL_SCHEMA),
+    ],
+    additional_properties: true,
+    default_key: None,
+};
+
+#[derive(Deserialize)]
+struct DummyPbsUser {
+    pub email: Option<String>,
+}
+
+/// Extract the root user's email address from the PBS user config.
+fn lookup_mail_address(content: &str, username: &str) -> Option<String> {
+    let mut config = SectionConfig::new(&DUMMY_ID_SCHEMA).allow_unknown_sections(true);
+    let user_plugin = SectionConfigPlugin::new(
+        "user".to_string(),
+        Some("userid".to_string()),
+        &DUMMY_USER_SCHEMA,
+    );
+    config.register_plugin(user_plugin);
+
+    match config.parse(PBS_USER_CFG_FILENAME, content) {
+        Ok(parsed) => {
+            parsed.sections.get(username)?;
+            match parsed.lookup::<DummyPbsUser>("user", username) {
+                Ok(user) => common::normalize_for_return(user.email.as_deref()),
+                Err(err) => {
+                    log::error!("unable to parse {PBS_USER_CFG_FILENAME}: {err}");
+                    None
+                }
+            }
+        }
+        Err(err) => {
+            log::error!("unable to parse {PBS_USER_CFG_FILENAME}: {err}");
+            None
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct PBSContext;
+
+pub static PBS_CONTEXT: PBSContext = PBSContext;
+
+impl Context for PBSContext {
+    fn lookup_email_for_user(&self, user: &str) -> Option<String> {
+        let content = common::attempt_file_read(PBS_USER_CFG_FILENAME);
+        content.and_then(|content| lookup_mail_address(&content, user))
+    }
+
+    fn default_sendmail_author(&self) -> String {
+        "Proxmox Backup Server".into()
+    }
+
+    fn default_sendmail_from(&self) -> String {
+        let content = common::attempt_file_read(PBS_NODE_CFG_FILENAME);
+        content
+            .and_then(|content| common::lookup_datacenter_config_key(&content, "email-from"))
+            .unwrap_or_else(|| String::from("root"))
+    }
+
+    fn http_proxy_config(&self) -> Option<String> {
+        let content = common::attempt_file_read(PBS_NODE_CFG_FILENAME);
+        content.and_then(|content| common::lookup_datacenter_config_key(&content, "http-proxy"))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const USER_CONFIG: &str = "
+user: root@pam
+	email root@example.com
+
+user: test@pbs
+	enable true
+	expire 0
+    ";
+
+    #[test]
+    fn test_parse_mail() {
+        assert_eq!(
+            lookup_mail_address(USER_CONFIG, "root@pam"),
+            Some("root@example.com".to_string())
+        );
+        assert_eq!(lookup_mail_address(USER_CONFIG, "test@pbs"), None);
+    }
+
+    const NODE_CONFIG: &str = "
+default-lang: de
+email-from: root@example.com
+http-proxy: http://localhost:1234
+    ";
+
+    #[test]
+    fn test_parse_node_config() {
+        assert_eq!(
+            common::lookup_datacenter_config_key(NODE_CONFIG, "email-from"),
+            Some("root@example.com".to_string())
+        );
+        assert_eq!(
+            common::lookup_datacenter_config_key(NODE_CONFIG, "http-proxy"),
+            Some("http://localhost:1234".to_string())
+        );
+        assert_eq!(
+            common::lookup_datacenter_config_key(NODE_CONFIG, "foo"),
+            None
+        );
+    }
+}

proxmox-notify/src/context/pve.rs

@@ -0,0 +1,82 @@
+use crate::context::{common, Context};
+
+fn lookup_mail_address(content: &str, user: &str) -> Option<String> {
+    common::normalize_for_return(content.lines().find_map(|line| {
+        let fields: Vec<&str> = line.split(':').collect();
+        #[allow(clippy::get_first)] // to keep expression style consistent
+        match fields.get(0)?.trim() == "user" && fields.get(1)?.trim() == user {
+            true => fields.get(6).copied(),
+            false => None,
+        }
+    }))
+}
+
+#[derive(Debug)]
+pub struct PVEContext;
+
+impl Context for PVEContext {
+    fn lookup_email_for_user(&self, user: &str) -> Option<String> {
+        let content = common::attempt_file_read("/etc/pve/user.cfg");
+        content.and_then(|content| lookup_mail_address(&content, user))
+    }
+
+    fn default_sendmail_author(&self) -> String {
+        "Proxmox VE".into()
+    }
+
+    fn default_sendmail_from(&self) -> String {
+        let content = common::attempt_file_read("/etc/pve/datacenter.cfg");
+        content
+            .and_then(|content| common::lookup_datacenter_config_key(&content, "email_from"))
+            .unwrap_or_else(|| String::from("root"))
+    }
+
+    fn http_proxy_config(&self) -> Option<String> {
+        let content = common::attempt_file_read("/etc/pve/datacenter.cfg");
+        content.and_then(|content| common::lookup_datacenter_config_key(&content, "http_proxy"))
+    }
+}
+
+pub static PVE_CONTEXT: PVEContext = PVEContext;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const USER_CONFIG: &str = "
+user:root@pam:1:0:::root@example.com:::
+user:test@pve:1:0:::test@example.com:::
+user:no-mail@pve:1:0::::::
+    ";
+
+    #[test]
+    fn test_parse_mail() {
+        assert_eq!(
+            lookup_mail_address(USER_CONFIG, "root@pam"),
+            Some("root@example.com".to_string())
+        );
+        assert_eq!(
+            lookup_mail_address(USER_CONFIG, "test@pve"),
+            Some("test@example.com".to_string())
+        );
+        assert_eq!(lookup_mail_address(USER_CONFIG, "no-mail@pve"), None);
+    }
+
+    const DC_CONFIG: &str = "
+email_from: user@example.com
+http_proxy: http://localhost:1234
+keyboard: en-us
+";
+    #[test]
+    fn test_parse_dc_config() {
+        assert_eq!(
+            common::lookup_datacenter_config_key(DC_CONFIG, "email_from"),
+            Some("user@example.com".to_string())
+        );
+        assert_eq!(
+            common::lookup_datacenter_config_key(DC_CONFIG, "http_proxy"),
+            Some("http://localhost:1234".to_string())
+        );
+        assert_eq!(common::lookup_datacenter_config_key(DC_CONFIG, "foo"), None);
+    }
+}