1 files changed, 130 insertions, 0 deletions
diff --git a/src/bundle/fetch.rs b/src/bundle/fetch.rs
new file mode 100644
index 0000000..4e58000
--- /dev/null
+++ b/src/bundle/fetch.rs
@@ -0,0 +1,130 @@
+// Copyright © 2022 Kim Altintop <kim@eagain.io>
+// SPDX-License-Identifier: GPL-2.0-only WITH openvpn-openssl-exception
+
+use std::{
+    fs,
+    io::{
+        self,
+        Read,
+        Seek,
+        SeekFrom,
+        Write,
+    },
+    path::{
+        Path,
+        PathBuf,
+    },
+};
+
+use anyhow::ensure;
+use either::Either::{
+    self,
+    Left,
+    Right,
+};
+use sha2::{
+    Digest,
+    Sha256,
+};
+use tempfile::NamedTempFile;
+use url::Url;
+
+use super::{
+    header,
+    Expect,
+    Header,
+};
+use crate::{
+    bundle,
+    fs::LockedFile,
+    git,
+    io::HashWriter,
+};
+
+const MAX_BUNDLE_URIS_BYTES: u64 = 50_000;
+
+pub struct Fetched {
+    path: PathBuf,
+    info: bundle::Info,
+}
+
+impl Fetched {
+    pub fn into_inner(self) -> (PathBuf, bundle::Info) {
+        (self.path, self.info)
+    }
+}
+
+pub struct Fetcher {
+    agent: ureq::Agent,
+}
+
+impl Default for Fetcher {
+    fn default() -> Self {
+        Self {
+            agent: ureq::agent(),
+        }
+    }
+}
+
+impl Fetcher {
+    pub fn fetch(
+        &self,
+        url: &Url,
+        out_dir: &Path,
+        expect: Expect,
+    ) -> crate::Result<Either<bundle::List, Fetched>> {
+        let resp = self.agent.request_url("GET", url).call()?;
+        let mut body = resp.into_reader();
+
+        let mut buf = [0; 16];
+        body.read_exact(&mut buf)?;
+        let is_bundle = buf.starts_with(header::SIGNATURE_V2.as_bytes())
+            || buf.starts_with(header::SIGNATURE_V3.as_bytes());
+        if is_bundle {
+            ensure!(
+                matches!(buf.last(), Some(b'\n')),
+                "malformed bundle header: trailing data"
+            )
+        }
+
+        if is_bundle {
+            let mut path = out_dir.join(expect.hash.to_string());
+            path.set_extension(bundle::FILE_EXTENSION);
+
+            let mut lck = {
+                fs::create_dir_all(out_dir)?;
+                LockedFile::atomic(&path, true, LockedFile::DEFAULT_PERMISSIONS)?
+            };
+
+            let mut out = HashWriter::new(Sha256::new(), &mut lck);
+            out.write_all(&buf)?;
+
+            let len = buf.len() as u64 + io::copy(&mut body.take(expect.len), &mut out)?;
+            let checksum = out.hash().into();
+            if let Some(chk) = expect.checksum {
+                ensure!(chk == checksum, "checksum mismatch");
+            }
+            lck.seek(SeekFrom::Start(0))?;
+            let header = Header::from_reader(&mut lck)?;
+            let hash = header.hash();
+
+            lck.persist()?;
+
+            let info = bundle::Info {
+                len,
+                hash,
+                checksum,
+                uris: vec![url.clone()],
+            };
+            Ok(Right(Fetched { path, info }))
+        } else {
+            let mut tmp = NamedTempFile::new()?;
+            tmp.write_all(&buf)?;
+            io::copy(&mut body.take(MAX_BUNDLE_URIS_BYTES), &mut tmp)?;
+            let cfg = git::config::Snapshot::try_from(git2::Config::open(tmp.path())?)?;
+            let list = bundle::List::from_config(cfg)?;
+
+            Ok(Left(list))
+        }
+    }
+}