feat(KAN-52): add server selection and isolated native sessions

native/src-tauri/src/server.rs

@@ -0,0 +1,137 @@
+use std::{fs, io, io::Read, path::Path};
+use tauri::Url;
+
+pub const DEFAULT_SERVER: &str = "https://kanbangit.de/";
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct Server {
+    pub url: Url,
+    pub profile: [u8; 16],
+}
+
+pub fn validate_url(input: &str) -> Result<Url, &'static str> {
+    let input = input.trim();
+    if !input
+        .get(..8)
+        .is_some_and(|prefix| prefix.eq_ignore_ascii_case("https://"))
+        || input
+            .chars()
+            .any(|character| character.is_control() || character == '\\')
+    {
+        return Err("invalidServer");
+    }
+    let mut url = Url::parse(input).map_err(|_| "invalidServer")?;
+    if url.scheme() != "https"
+        || url.host_str().is_none()
+        || !url.username().is_empty()
+        || url.password().is_some()
+        || url.query().is_some()
+        || url.fragment().is_some()
+    {
+        return Err("invalidServer");
+    }
+    if !url.path().ends_with('/') {
+        url.set_path(&format!("{}/", url.path()));
+    }
+    Ok(url)
+}
+
+impl Server {
+    pub fn new(url: Url) -> io::Result<Self> {
+        let mut profile = [0; 16];
+        fs::File::open("/dev/urandom")?.read_exact(&mut profile)?;
+        Ok(Self { url, profile })
+    }
+
+    pub fn load(path: &Path) -> io::Result<Option<Self>> {
+        let contents = match fs::read_to_string(path) {
+            Ok(contents) => contents,
+            Err(error) if error.kind() == io::ErrorKind::NotFound => return Ok(None),
+            Err(error) => return Err(error),
+        };
+        let invalid = || io::Error::new(io::ErrorKind::InvalidData, "Invalid server configuration");
+        let (url, profile) = contents.split_once('\n').ok_or_else(invalid)?;
+        let url = validate_url(url).map_err(|_| invalid())?;
+        if profile.len() != 32 || !profile.is_ascii() {
+            return Err(invalid());
+        }
+        let mut bytes = [0; 16];
+        for (index, byte) in bytes.iter_mut().enumerate() {
+            *byte = u8::from_str_radix(&profile[index * 2..index * 2 + 2], 16)
+                .map_err(|_| invalid())?;
+        }
+        Ok(Some(Self {
+            url,
+            profile: bytes,
+        }))
+    }
+
+    pub fn save(&self, path: &Path) -> io::Result<()> {
+        if let Some(parent) = path.parent() {
+            fs::create_dir_all(parent)?;
+        }
+        let profile: String = self
+            .profile
+            .iter()
+            .map(|byte| format!("{byte:02x}"))
+            .collect();
+        let temporary = path.with_extension("tmp");
+        fs::write(&temporary, format!("{}\n{profile}", self.url))?;
+        fs::rename(temporary, path)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn validates_and_normalizes_installation_addresses() {
+        assert_eq!(
+            validate_url(" HTTPS://Example.com:443/kanban ")
+                .unwrap()
+                .as_str(),
+            "https://example.com/kanban/"
+        );
+        assert!(validate_url("https://[::1]:8443/").is_ok());
+        for input in [
+            "http://example.com",
+            "https:example.com",
+            "https://user:secret@example.com",
+            "https://user@example.com",
+            "https://example.com/?token=secret",
+            "https://example.com/#secret",
+            "https://exa\nmple.com",
+            "https://example.com\\other",
+            "file:///tmp/test",
+            "javascript:alert(1)",
+            "",
+        ] {
+            assert!(validate_url(input).is_err(), "{input}");
+        }
+    }
+
+    #[test]
+    fn configuration_round_trip_preserves_only_the_address_and_profile() {
+        let server = Server::new(validate_url(DEFAULT_SERVER).unwrap()).unwrap();
+        let path =
+            std::env::temp_dir().join(format!("kanbangit-server-{:x?}/active", server.profile));
+        assert_eq!(Server::load(&path).unwrap(), None);
+        server.save(&path).unwrap();
+        assert_eq!(Server::load(&path).unwrap(), Some(server.clone()));
+        let other = Server::new(validate_url("https://other.example.com:444/").unwrap()).unwrap();
+        assert_ne!(server.profile, other.profile);
+        other.save(&path).unwrap();
+        assert_eq!(Server::load(&path).unwrap(), Some(other));
+        for contents in [
+            "http://example.com/\n00000000000000000000000000000000",
+            "invalid",
+            "https://example.com/\nshort",
+            "https://example.com/\nzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz",
+        ] {
+            fs::write(&path, contents).unwrap();
+            assert!(Server::load(&path).is_err());
+        }
+        fs::remove_dir_all(path.parent().unwrap()).unwrap();
+    }
+}