build: validate CFG_SRC_URL and simplify CFG_RELEASE handling

blahctl/src/main.rs

@@ -16,7 +16,10 @@ use reqwest::Url;
 use rusqlite::{named_params, prepare_and_bind, Connection};
 use tokio::runtime::Runtime;
 
-const USER_AGENT: &str = concat!("blahctl/", env!("CARGO_PKG_VERSION"));
+const USER_AGENT: fn() -> String = || match option_env!("CFG_RELEASE") {
+    None => concat!("blahctl/", env!("CARGO_PKG_VERSION")).into(),
+    Some(vers) => format!("blahctl/{vers}"),
+};
 
 /// Control or manage Blah Chat Server.
 #[derive(Debug, clap::Parser)]
@@ -337,7 +340,7 @@ fn build_rt() -> Result<Runtime> {
 
 fn build_client() -> Result<reqwest::Client> {
     reqwest::Client::builder()
-        .user_agent(USER_AGENT)
+        .user_agent(USER_AGENT())
         .redirect(reqwest::redirect::Policy::none())
         .build()
         .context("failed to build HTTP client")

blahd/Cargo.toml

@@ -38,6 +38,9 @@ url = { version = "2", features = ["serde"] }
 
 blah-types = { path = "../blah-types", features = ["rusqlite"] }
 
+[build-dependencies]
+url = "2"
+
 [dev-dependencies]
 expect-test = "1"
 nix = { version = "0.29", features = ["fs", "process", "signal"] }

blahd/build.rs

@@ -0,0 +1,20 @@
+fn main() {
+    // No rerun on file changes.
+    println!("cargo::rerun-if-changed=build.rs");
+
+    println!("cargo::rerun-if-env-changed=CFG_RELEASE");
+    if std::env::var_os("CFG_RELEASE").is_none() {
+        let vers = std::env::var("CARGO_PKG_VERSION").expect("cargo should set it");
+        println!("cargo::rustc-env=CFG_RELEASE={vers}");
+    }
+
+    println!("cargo::rerun-if-env-changed=CFG_SRC_URL");
+    if let Some(url) = std::env::var_os("CFG_SRC_URL") {
+        url.to_str()
+            .expect("CFG_SRC_URL is not in UTF-8")
+            .parse::<url::Url>()
+            .expect("CFG_SRC_URL is not a valid URL");
+    } else {
+        println!("cargo::warning=CFG_SRC_URL is not set");
+    }
+}

blahd/src/bin/blahd.rs

@@ -10,7 +10,7 @@ use tokio::signal::unix::{signal, SignalKind};
 
 /// Blah Chat Server
 #[derive(Debug, clap::Parser)]
-#[clap(about, version = option_env!("CFG_RELEASE").unwrap_or(env!("CARGO_PKG_VERSION")))]
+#[clap(about, version = env!("CFG_RELEASE"))]
 enum Cli {
     /// Run the server with given configuration.
     Serve {

blahd/src/lib.rs

@@ -100,11 +100,7 @@ impl AppState {
     pub fn new(db: Database, config: ServerConfig) -> Self {
         let meta = ServerMetadata {
             server: SERVER_AND_VERSION.into(),
-            // TODO: Validate this at compile time?
+            src_url: SERVER_SRC_URL.map(|url| url.parse().expect("checked by build script")),
-            src_url: SERVER_SRC_URL.map(|url| {
-                url.parse()
-                    .expect("BLAHD_SRC_URL from compile time should be valid")
-            }),
             capabilities: ServerCapabilities {
                 allow_public_register: config.register.enable_public,
             },

blahd/src/register.rs

@@ -15,9 +15,7 @@ use serde::Deserialize;
 use sha2::{Digest, Sha256};
 
 use crate::database::TransactionOps;
-use crate::{ApiError, AppState};
+use crate::{ApiError, AppState, SERVER_AND_VERSION};
-
-const USER_AGENT: &str = concat!("blahd/", env!("CARGO_PKG_VERSION"));
 
 #[derive(Debug, Clone, PartialEq, Eq, Deserialize)]
 #[serde(default, deny_unknown_fields)]
@@ -94,7 +92,7 @@ impl State {
     pub fn new(config: Config) -> Self {
         // TODO: Audit this.
         let client = reqwest::ClientBuilder::new()
-            .user_agent(USER_AGENT)
+            .user_agent(SERVER_AND_VERSION)
             .redirect(reqwest::redirect::Policy::none())
             .timeout(Duration::from_secs(config.request_timeout_secs))
             .build()