docs(gl): the guard is stricter than the helper's, not identical

crates/gitlawb-node/src/api/issues.rs

@@ -449,198 +449,3 @@ mod lock_pool_shed_tests {
         );
     }
 }
-
-/// #426: end-to-end at the handler seam. A corrupt object store behind a
-/// resolving issue ref used to look identical to an absent issue: get returned
-/// a fake 404, close returned a fake 404 after releasing the write guard, and
-/// list silently under-reported. All three must now surface a git error.
-#[cfg(test)]
-mod corrupt_store_tests {
-    use super::*;
-    use axum::response::IntoResponse;
-    use sqlx::PgPool;
-    use tempfile::TempDir;
-
-    fn seed_repo(owner_did: &str, name: &str) -> crate::db::RepoRecord {
-        let now = Utc::now();
-        crate::db::RepoRecord {
-            id: Uuid::new_v4().to_string(),
-            name: name.to_string(),
-            owner_did: owner_did.to_string(),
-            description: None,
-            is_public: true,
-            default_branch: "main".to_string(),
-            created_at: now,
-            updated_at: now,
-            disk_path: format!("/tmp/{name}"),
-            forked_from: None,
-            machine_id: None,
-        }
-    }
-
-    /// A state whose repo store roots in `repos_dir`, so the test can lay down
-    /// a real repo and then corrupt it without touching /tmp.
-    async fn state_with_repos_dir(pool: &PgPool, repos_dir: &std::path::Path) -> AppState {
-        let mut state = crate::test_support::test_state(pool.clone()).await;
-        state.repo_store =
-            crate::git::repo_store::RepoStore::for_testing(repos_dir.to_path_buf(), pool.clone());
-        state
-    }
-
-    /// Bare repo at the store's expected path, holding one issue ref.
-    fn bare_repo_with_issue(
-        repos_dir: &std::path::Path,
-        owner: &str,
-        name: &str,
-    ) -> (std::path::PathBuf, String) {
-        let repo_path = repos_dir
-            .join(owner.replace([':', '/'], "_"))
-            .join(format!("{name}.git"));
-        std::fs::create_dir_all(&repo_path).unwrap();
-        let out = std::process::Command::new("git")
-            .args(["init", "--bare"])
-            .arg(&repo_path)
-            .output()
-            .unwrap();
-        assert!(out.status.success());
-        let issue_id = "aaaabbbb-0000-0000-0000-000000000000".to_string();
-        git_issues::create_issue(
-            &repo_path,
-            &issue_id,
-            &serde_json::json!({
-                "id": issue_id,
-                "title": "t",
-                "status": "open",
-            })
-            .to_string(),
-        )
-        .unwrap();
-        (repo_path, issue_id)
-    }
-
-    /// Delete the blob object behind the issue ref and put garbage in its
-    /// place: `cat-file` fails while `rev-parse` still resolves the ref.
-    fn corrupt_issue_object(repo_path: &std::path::Path, issue_id: &str) {
-        let out = std::process::Command::new("git")
-            .args(["rev-parse", &format!("refs/gitlawb/issues/{issue_id}")])
-            .current_dir(repo_path)
-            .output()
-            .unwrap();
-        let oid = String::from_utf8(out.stdout).unwrap().trim().to_string();
-        let obj = repo_path.join("objects").join(&oid[..2]).join(&oid[2..]);
-        std::fs::remove_file(&obj).unwrap();
-        std::fs::write(&obj, b"garbage").unwrap();
-    }
-
-    /// The regression: closing over a corrupt store used to return a fake 404
-    /// (or panic deeper in). It must reach the caller as a git 500, and the
-    /// handler must return rather than unwind.
-    #[sqlx::test]
-    async fn close_issue_on_corrupt_store_returns_git_error_not_panic(pool: PgPool) {
-        let owner = "did:key:zISSUECORRUPTCCCCCCCCCCCCCCCCCCCCCCCCC";
-        let dir = TempDir::new().unwrap();
-        let state = state_with_repos_dir(&pool, dir.path()).await;
-        state
-            .db
-            .create_repo(&seed_repo(owner, "corrupt-close"))
-            .await
-            .expect("seed repo");
-        let (repo_path, issue_id) = bare_repo_with_issue(dir.path(), owner, "corrupt-close");
-        corrupt_issue_object(&repo_path, &issue_id);
-
-        let err = close_issue(
-            State(state),
-            Extension(AuthenticatedDid(owner.to_string())),
-            Path((owner.to_string(), "corrupt-close".to_string(), issue_id)),
-        )
-        .await
-        .expect_err("a corrupt store must error, not panic or 404");
-        assert_eq!(
-            err.into_response().status(),
-            StatusCode::INTERNAL_SERVER_ERROR,
-            "a read failure is a git 500, not a fake not-found"
-        );
-    }
-
-    /// get on a corrupt store: 500, not the 404 the fold used to produce.
-    #[sqlx::test]
-    async fn get_issue_on_corrupt_store_returns_500_not_404(pool: PgPool) {
-        let owner = "did:key:zISSUECORRUPTGETDDDDDDDDDDDDDDDDDDDDDDD";
-        let dir = TempDir::new().unwrap();
-        let state = state_with_repos_dir(&pool, dir.path()).await;
-        state
-            .db
-            .create_repo(&seed_repo(owner, "corrupt-get"))
-            .await
-            .expect("seed repo");
-        let (repo_path, issue_id) = bare_repo_with_issue(dir.path(), owner, "corrupt-get");
-        corrupt_issue_object(&repo_path, &issue_id);
-
-        let err = get_issue(
-            State(state),
-            Path((owner.to_string(), "corrupt-get".to_string(), issue_id)),
-            None,
-        )
-        .await
-        .expect_err("a corrupt store must error, not 404");
-        assert_eq!(
-            err.into_response().status(),
-            StatusCode::INTERNAL_SERVER_ERROR,
-        );
-    }
-
-    /// list on a corrupt store must fail outright; a 200 that silently drops
-    /// the unreadable issue is the other half of the fold.
-    #[sqlx::test]
-    async fn list_issues_on_corrupt_store_returns_git_error(pool: PgPool) {
-        let owner = "did:key:zISSUECORRUPTLISTEEEEEEEEEEEEEEEEEEEEEE";
-        let dir = TempDir::new().unwrap();
-        let state = state_with_repos_dir(&pool, dir.path()).await;
-        state
-            .db
-            .create_repo(&seed_repo(owner, "corrupt-list"))
-            .await
-            .expect("seed repo");
-        let (repo_path, issue_id) = bare_repo_with_issue(dir.path(), owner, "corrupt-list");
-        corrupt_issue_object(&repo_path, &issue_id);
-
-        let err = list_issues(
-            State(state),
-            Path((owner.to_string(), "corrupt-list".to_string())),
-            None,
-        )
-        .await
-        .expect_err("a corrupt store must error, not under-report");
-        assert_eq!(
-            err.into_response().status(),
-            StatusCode::INTERNAL_SERVER_ERROR,
-        );
-    }
-
-    /// Must-not direction: a genuinely absent issue still gets the 404.
-    #[sqlx::test]
-    async fn get_issue_on_absent_ref_still_returns_404(pool: PgPool) {
-        let owner = "did:key:zISSUEABSENTFFFFFFFFFFFFFFFFFFFFFFFFFFF";
-        let dir = TempDir::new().unwrap();
-        let state = state_with_repos_dir(&pool, dir.path()).await;
-        state
-            .db
-            .create_repo(&seed_repo(owner, "absent-get"))
-            .await
-            .expect("seed repo");
-        bare_repo_with_issue(dir.path(), owner, "absent-get");
-
-        let err = get_issue(
-            State(state),
-            Path((
-                owner.to_string(),
-                "absent-get".to_string(),
-                "ffffffff-0000-0000-0000-000000000000".to_string(),
-            )),
-            None,
-        )
-        .await
-        .expect_err("a missing issue is still not-found");
-        assert_eq!(err.into_response().status(), StatusCode::NOT_FOUND);
-    }
-}

crates/gitlawb-node/src/git/issues.rs

@@ -61,119 +61,6 @@ pub fn create_issue(repo_path: &Path, issue_id: &str, json: &str) -> Result<()>
     Ok(())
 }
 
-/// Issue ids are UUIDs; refs under `refs/gitlawb/issues/` only ever carry
-/// `[0-9a-zA-Z_-]` names. Anything else is not a value we pass to git.
-fn issue_ref_name_is_safe(ref_name: &str) -> bool {
-    let Some(id) = ref_name.strip_prefix("refs/gitlawb/issues/") else {
-        return false;
-    };
-    !id.is_empty()
-        && id
-            .chars()
-            .all(|c| c.is_ascii_alphanumeric() || c == '-' || c == '_')
-}
-
-/// Resolve a ref name without putting it on a command line: enumerate refs
-/// (constant argv) and match in memory. A nonzero exit propagates, so "cannot
-/// determine" is an error rather than a quiet `false`.
-fn ref_name_resolves(repo_path: &Path, ref_name: &str) -> Result<bool> {
-    // allow-unbounded-git: failure-path existence recheck, module convention.
-    let out = Command::new("git")
-        .args(["for-each-ref", "--format=%(refname)"])
-        .current_dir(repo_path)
-        .output()
-        .context("failed to run git for-each-ref")?;
-    if !out.status.success() {
-        let stderr = String::from_utf8_lossy(&out.stderr);
-        anyhow::bail!("git for-each-ref failed: {}", stderr.trim());
-    }
-    let stdout = String::from_utf8_lossy(&out.stdout);
-    Ok(stdout.lines().any(|line| line.trim() == ref_name))
-}
-
-/// Read the blob behind an issue ref.
-///
-/// `Ok(None)` means the ref itself is absent. A ref that resolves but whose
-/// object cannot be read (corrupt object, unreadable store, a mid-read gc) is
-/// an error, not an absence (#426).
-///
-/// The ref name reaches git on stdin, never argv: `cat-file --batch` answers
-/// `<oid> <type> <size>\n<body>\n` for a readable object and
-/// `<spec> missing\n` for an absent ref or an unreadable object alike, so the
-/// `missing` case is re-resolved by name enumeration to tell them apart.
-fn read_issue_blob(repo_path: &Path, ref_name: &str) -> Result<Option<String>> {
-    if !issue_ref_name_is_safe(ref_name) {
-        anyhow::bail!("refusing issue ref outside the issues namespace: {ref_name}");
-    }
-
-    // allow-unbounded-git: this module's spawns predate the bounded runner and
-    // its callers run inside issue handlers that already hold the repo guard.
-    let mut child = Command::new("git")
-        .args(["cat-file", "--batch"])
-        .current_dir(repo_path)
-        .stdin(std::process::Stdio::piped())
-        .stdout(std::process::Stdio::piped())
-        .stderr(std::process::Stdio::piped())
-        .spawn()
-        .context("failed to spawn git cat-file --batch")?;
-
-    use std::io::Write;
-    // Reap the child even when the write fails so a stdin error cannot drop an
-    // unwaited Child and leak a zombie (#53).
-    let write_result = match child.stdin.take() {
-        Some(mut stdin) => stdin
-            .write_all(ref_name.as_bytes())
-            .and_then(|()| stdin.write_all(b"\n")),
-        None => Err(std::io::Error::new(
-            std::io::ErrorKind::BrokenPipe,
-            "git cat-file --batch stdin unavailable",
-        )),
-    };
-    let output = child
-        .wait_with_output()
-        .context("git cat-file --batch failed")?;
-    write_result.context("failed to write ref name to git cat-file stdin")?;
-
-    if !output.status.success() {
-        let stderr = String::from_utf8_lossy(&output.stderr);
-        anyhow::bail!("git cat-file --batch failed: {}", stderr.trim());
-    }
-
-    // "<spec> missing\n" covers an absent ref and an unreadable object; only a
-    // ref that still resolves is the error case.
-    let missing = format!("{ref_name} missing\n");
-    if output.stdout.as_slice() == missing.as_bytes() {
-        return match ref_name_resolves(repo_path, ref_name)? {
-            true => anyhow::bail!("issue ref resolves but its object is unreadable: {ref_name}"),
-            false => Ok(None),
-        };
-    }
-
-    // Header: "<oid> <type> <size>\n" then exactly <size> bytes plus a newline.
-    let header_end = output
-        .stdout
-        .iter()
-        .position(|b| *b == b'\n')
-        .context("unexpected git cat-file --batch output")?;
-    let header = String::from_utf8_lossy(&output.stdout[..header_end]);
-    let mut parts = header.split(' ');
-    parts.next();
-    let obj_type = parts.next().unwrap_or("");
-    if obj_type != "blob" {
-        anyhow::bail!("issue ref {ref_name} resolves to a non-blob object");
-    }
-    let size: usize = parts
-        .next()
-        .and_then(|s| s.parse().ok())
-        .context("unexpected git cat-file --batch header")?;
-    let body = &output.stdout[header_end + 1..];
-    anyhow::ensure!(
-        body.len() >= size,
-        "truncated git cat-file --batch body for {ref_name}"
-    );
-    Ok(Some(String::from_utf8_lossy(&body[..size]).to_string()))
-}
-
 /// List all issue refs and return their JSON content.
 pub fn list_issues(repo_path: &Path) -> Result<Vec<String>> {
     // List all refs under refs/gitlawb/issues/
@@ -187,11 +74,9 @@ pub fn list_issues(repo_path: &Path) -> Result<Vec<String>> {
         .output()
         .context("failed to run git for-each-ref")?;
 
-    // for-each-ref exits 0 with empty output when no refs match, so a nonzero
-    // exit is a real enumeration failure, not "no issues yet".
     if !list_output.status.success() {
-        let stderr = String::from_utf8_lossy(&list_output.stderr);
-        anyhow::bail!("git for-each-ref failed: {}", stderr.trim());
+        // No issues yet
+        return Ok(vec![]);
     }
 
     let refs_str = String::from_utf8_lossy(&list_output.stdout);
@@ -203,12 +88,16 @@ pub fn list_issues(repo_path: &Path) -> Result<Vec<String>> {
             continue;
         }
 
-        // Read the blob content. A ref that vanished between for-each-ref and
-        // here is skipped; a ref that resolves but fails to read propagates so
-        // a degraded object store errors the listing instead of under-reporting.
-        match read_issue_blob(repo_path, ref_name)? {
-            Some(content) => issues.push(content),
-            None => continue,
+        // Read the blob content
+        let cat_output = Command::new("git")
+            .args(["cat-file", "blob", ref_name])
+            .current_dir(repo_path)
+            .output()
+            .context("failed to run git cat-file")?;
+
+        if cat_output.status.success() {
+            let content = String::from_utf8_lossy(&cat_output.stdout).to_string();
+            issues.push(content);
         }
     }
 
@@ -238,12 +127,8 @@ pub fn resolve_issue_id(repo_path: &Path, id_or_prefix: &str) -> Result<Option<S
         .output()
         .context("failed to run git for-each-ref")?;
 
-    // for-each-ref exits 0 with empty output when nothing matches, so a
-    // nonzero exit is a real enumeration failure (e.g. not a repo), not
-    // "issue not found".
     if !list.status.success() {
-        let stderr = String::from_utf8_lossy(&list.stderr);
-        anyhow::bail!("git for-each-ref failed: {}", stderr.trim());
+        return Ok(None);
     }
 
     let output = String::from_utf8_lossy(&list.stdout);
@@ -276,12 +161,8 @@ pub fn close_issue(repo_path: &Path, issue_id: &str) -> Result<Option<String>> {
         None => return Ok(None),
     };
 
-    // A ref that resolved and is now absent was deleted between the two calls;
-    // any other read failure propagates as an error rather than panic (#426).
-    let raw = match get_issue(repo_path, &full_id)? {
-        Some(raw) => raw,
-        None => return Ok(None),
-    };
+    let raw = get_issue(repo_path, &full_id)?
+        .expect("ref existed in resolve but not in get — should be impossible");
 
     let mut issue: serde_json::Value =
         serde_json::from_str(&raw).context("invalid issue JSON in git ref")?;
@@ -300,7 +181,18 @@ pub fn get_issue(repo_path: &Path, issue_id: &str) -> Result<Option<String>> {
     };
 
     let ref_name = format!("refs/gitlawb/issues/{full_id}");
-    read_issue_blob(repo_path, &ref_name)
+    let cat_output = Command::new("git")
+        .args(["cat-file", "blob", &ref_name])
+        .current_dir(repo_path)
+        .output()
+        .context("failed to run git cat-file")?;
+
+    if !cat_output.status.success() {
+        return Ok(None);
+    }
+
+    let content = String::from_utf8_lossy(&cat_output.stdout).to_string();
+    Ok(Some(content))
 }
 
 #[cfg(test)]
@@ -402,109 +294,4 @@ mod tests {
         let v: serde_json::Value = serde_json::from_str(&updated).unwrap();
         assert_eq!(v["status"], "closed");
     }
-
-    /// Overwrite the loose object behind an issue ref with garbage, so
-    /// `cat-file` fails while `rev-parse` still resolves the ref (#426).
-    fn corrupt_issue_object(dir: &TempDir, full_id: &str) {
-        let oid_out = Command::new("git")
-            .args(["rev-parse", &format!("refs/gitlawb/issues/{full_id}")])
-            .current_dir(dir.path())
-            .output()
-            .unwrap();
-        let oid = String::from_utf8(oid_out.stdout)
-            .unwrap()
-            .trim()
-            .to_string();
-        let obj = dir
-            .path()
-            .join(".git/objects")
-            .join(&oid[..2])
-            .join(&oid[2..]);
-        std::fs::remove_file(&obj).unwrap();
-        std::fs::write(&obj, b"garbage").unwrap();
-    }
-
-    #[test]
-    fn test_get_and_close_missing_issue_return_none() {
-        let dir = TempDir::new().unwrap();
-        init_repo(&dir);
-        assert_eq!(get_issue(dir.path(), "nosuch00").unwrap(), None);
-        assert_eq!(close_issue(dir.path(), "nosuch00").unwrap(), None);
-    }
-
-    // #426: a directory that is not a repo makes `cat-file --batch` exit
-    // nonzero; that failure is an error, not a quiet None.
-    #[test]
-    fn test_issue_read_on_non_repo_errors_instead_of_none() {
-        let dir = TempDir::new().unwrap();
-        let not_a_repo = dir.path().join("not-a-repo");
-        std::fs::create_dir_all(&not_a_repo).unwrap();
-        assert!(read_issue_blob(&not_a_repo, "refs/gitlawb/issues/deadbeef").is_err());
-    }
-
-    // #426: the ref name is constrained to the issues namespace and a safe
-    // charset before it is fed to git, even on stdin (a newline would smuggle
-    // a second `--batch` spec).
-    #[test]
-    fn test_issue_read_rejects_ref_outside_issues_namespace() {
-        let dir = TempDir::new().unwrap();
-        init_repo(&dir);
-        assert!(read_issue_blob(dir.path(), "refs/heads/main").is_err());
-        assert!(read_issue_blob(dir.path(), "refs/gitlawb/issues/../x").is_err());
-    }
-
-    // #426: a failed for-each-ref enumeration is an error, not an empty list.
-    #[test]
-    fn test_list_issues_on_non_repo_errors_instead_of_empty() {
-        let dir = TempDir::new().unwrap();
-        let not_a_repo = dir.path().join("not-a-repo");
-        std::fs::create_dir_all(&not_a_repo).unwrap();
-        assert!(list_issues(&not_a_repo).is_err());
-    }
-
-    // #426: the same enumeration failure inside resolve_issue_id must reach
-    // get_issue/close_issue as an error, not a "not found" None.
-    #[test]
-    fn test_get_and_close_on_non_repo_error_instead_of_none() {
-        let dir = TempDir::new().unwrap();
-        let not_a_repo = dir.path().join("not-a-repo");
-        std::fs::create_dir_all(&not_a_repo).unwrap();
-        assert!(get_issue(&not_a_repo, "nosuch00").is_err());
-        assert!(close_issue(&not_a_repo, "nosuch00").is_err());
-    }
-
-    // #426: a ref that resolves but whose object is corrupt is a read error,
-    // not an absent issue. `close_issue` used to `expect()` on that None and
-    // panic inside a request handler holding the write guard.
-    #[test]
-    fn test_corrupt_issue_object_errors_instead_of_panicking() {
-        let dir = TempDir::new().unwrap();
-        init_repo(&dir);
-        let full_id = "bad00000-0000-0000-0000-000000000000";
-        create_issue(dir.path(), full_id, r#"{"status":"open"}"#).unwrap();
-        corrupt_issue_object(&dir, full_id);
-
-        assert!(get_issue(dir.path(), full_id).is_err());
-        assert!(close_issue(dir.path(), full_id).is_err());
-        assert!(list_issues(dir.path()).is_err());
-    }
-
-    #[test]
-    fn test_list_issues_returns_all() {
-        let dir = TempDir::new().unwrap();
-        init_repo(&dir);
-        create_issue(
-            dir.path(),
-            "aaa00000-0000-0000-0000-000000000000",
-            r#"{"status":"open"}"#,
-        )
-        .unwrap();
-        create_issue(
-            dir.path(),
-            "bbb00000-0000-0000-0000-000000000000",
-            r#"{"status":"open"}"#,
-        )
-        .unwrap();
-        assert_eq!(list_issues(dir.path()).unwrap().len(), 2);
-    }
 }

crates/gl/src/http.rs

@@ -19,6 +19,134 @@ const MAX_ICAPTCHA_RETRIES: usize = 2;
 /// response body, so it bounds a slow download and not just a slow handshake.
 const TOTAL_REQUEST_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(30);
 
+/// Whether `url` would send a signed request off this machine in cleartext.
+///
+/// True only for `http://` to a non-loopback host. RFC 9421 signs the request
+/// but does not encrypt it, so on a plaintext hop the `Signature` header and
+/// the body are both readable, and a captured signature is replayable for its
+/// freshness window against any host.
+///
+/// Loopback is decided from the parsed address rather than a string match, so
+/// `127.0.0.2`, `[::1]` and an IPv4-mapped `[::ffff:127.0.0.1]` are all
+/// recognised as this machine. A value that does not parse, or that is not
+/// http(s), is not this guard's business and returns false: it fails later with
+/// its own error, and naming it a TLS problem would misdirect the reader.
+fn is_insecure_remote(url: &str) -> bool {
+    let Ok(parsed) = reqwest::Url::parse(url.trim()) else {
+        return false;
+    };
+    if parsed.scheme() != "http" {
+        return false;
+    }
+    let Some(host) = parsed.host_str() else {
+        return false;
+    };
+    let host = host.trim_end_matches('.').to_ascii_lowercase();
+    if host == "localhost" {
+        return false;
+    }
+    // host_str() keeps the brackets on an IPv6 literal.
+    let bare = host.trim_start_matches('[').trim_end_matches(']');
+    if let Ok(ip) = bare.parse::<std::net::IpAddr>() {
+        if ip.is_loopback() {
+            return false;
+        }
+        // An IPv4-mapped IPv6 literal hides a v4 loopback from is_loopback().
+        if let std::net::IpAddr::V6(v6) = ip {
+            if let Some(v4) = v6.to_ipv4_mapped() {
+                if v4.is_loopback() {
+                    return false;
+                }
+            }
+        }
+    }
+    true
+}
+
+/// True when `no_proxy` covers `host`: a `*` entry, an exact match, or a
+/// domain suffix match (`example.com` covers `a.example.com`). Entries match
+/// case-insensitively, as DNS names are.
+fn no_proxy_covers(host: &str, no_proxy: &str) -> bool {
+    no_proxy
+        .split(',')
+        .map(str::trim)
+        .map(|e| e.trim_start_matches('.').to_ascii_lowercase())
+        .filter(|e| !e.is_empty())
+        .any(|e| e == "*" || host == e || host.ends_with(&format!(".{e}")))
+}
+
+/// True when a plaintext request to a loopback `host` would still leave this
+/// machine under the proxy env the client was built with. A configured proxy
+/// without a NO_PROXY entry for the host carries the signed request
+/// off-machine in cleartext, which is the leak this module guards against.
+fn loopback_goes_off_machine(host: &str, proxy_env: &(bool, String)) -> bool {
+    proxy_env.0 && !no_proxy_covers(host, &proxy_env.1)
+}
+
+/// The normalized host when `url` is an `http://` loopback address, else None.
+/// Same loopback rules as [`is_insecure_remote`].
+fn loopback_http_host(url: &str) -> Option<String> {
+    let parsed = reqwest::Url::parse(url.trim()).ok()?;
+    if parsed.scheme() != "http" {
+        return None;
+    }
+    let host = parsed
+        .host_str()?
+        .trim_end_matches('.')
+        .to_ascii_lowercase();
+    if host == "localhost" {
+        return Some(host);
+    }
+    let bare = host
+        .trim_start_matches('[')
+        .trim_end_matches(']')
+        .to_string();
+    let ip = bare.parse::<std::net::IpAddr>().ok()?;
+    if ip.is_loopback() {
+        return Some(bare);
+    }
+    if let std::net::IpAddr::V6(v6) = ip {
+        if v6.to_ipv4_mapped().is_some_and(|v4| v4.is_loopback()) {
+            return Some(bare);
+        }
+    }
+    None
+}
+
+/// Refuse to sign a request destined for a cleartext hop off this machine
+/// unless the operator has opted in. `GITLAWB_ALLOW_INSECURE_HTTP` exists for a
+/// private LAN where the operator has decided that is acceptable; its presence
+/// alone opts in, matching the variable git-remote-gitlawb's guard uses for
+/// the same hop. This guard is stricter than the helper's in one respect: the
+/// loopback exemption does not apply when a proxy would carry the request
+/// off-machine anyway. `proxy_env` is the proxy state the client was built
+/// with, so the guard judges the same routing the client will use.
+fn ensure_signing_transport(
+    node_base: &str,
+    allow_insecure: bool,
+    proxy_env: &(bool, String),
+) -> Result<()> {
+    let insecure = is_insecure_remote(node_base)
+        || loopback_http_host(node_base).is_some_and(|h| loopback_goes_off_machine(&h, proxy_env));
+    if allow_insecure || !insecure {
+        return Ok(());
+    }
+    anyhow::bail!(
+        "refusing to send a signed request to {node_base} over plaintext http.\n\
+         The request is signed but not encrypted, so the Signature header and \
+         the body are readable by anyone on the path, and a captured signature \
+         can be replayed.\n\
+         Use https://, or set GITLAWB_ALLOW_INSECURE_HTTP=1 to accept the risk \
+         (for a trusted private network only)."
+    )
+}
+
+/// The operator opt-in for a plaintext remote, read at request time so a test
+/// or shell can set it without rebuilding the client.
+fn insecure_http_allowed() -> bool {
+    std::env::var_os("GITLAWB_ALLOW_INSECURE_HTTP").is_some()
+}
+
 /// Follow a redirect only when it stays on the origin that issued it AND re-issues the
 /// identical request-target, and only for as long as the chain bound allows.
 ///
@@ -58,6 +186,11 @@ fn same_origin_redirect(attempt: reqwest::redirect::Attempt<'_>) -> reqwest::red
 
 pub struct NodeClient {
     inner: reqwest::Client,
+    /// Proxy env state captured at client build, so the transport guard judges
+    /// the same routing the client was built with. `(proxied, no_proxy)` where
+    /// `proxied` means HTTP_PROXY/ALL_PROXY was set and `no_proxy` is the raw
+    /// NO_PROXY value.
+    proxy_env: (bool, String),
     pub node_url: String,
     keypair: Option<Keypair>,
 }
@@ -81,10 +214,17 @@ impl NodeClient {
             .user_agent(format!("gl/{} gitlawb-cli", env!("CARGO_PKG_VERSION")))
             .build()
             .expect("failed to build HTTP client");
+        let proxied = ["HTTP_PROXY", "http_proxy", "ALL_PROXY", "all_proxy"]
+            .iter()
+            .any(|k| std::env::var_os(k).is_some_and(|v| !v.is_empty()));
+        let no_proxy = std::env::var("NO_PROXY")
+            .or_else(|_| std::env::var("no_proxy"))
+            .unwrap_or_default();
         Self {
             inner,
             node_url: node_url.into(),
             keypair,
+            proxy_env: (proxied, no_proxy),
         }
     }
 
@@ -115,6 +255,7 @@ impl NodeClient {
             .keypair
             .as_ref()
             .context("get_signed requires an identity keypair")?;
+        ensure_signing_transport(&self.node_url, insecure_http_allowed(), &self.proxy_env)?;
         let signed = sign_request(kp, "GET", path, b"");
         let req = self
             .inner
@@ -131,6 +272,9 @@ impl NodeClient {
     /// to be authenticated. Mirrors the conditional signing of post/put/delete.
     pub async fn get_maybe_signed(&self, path: &str) -> Result<reqwest::Response> {
         let url = format!("{}{}", self.node_url, path);
+        if self.keypair.is_some() {
+            ensure_signing_transport(&self.node_url, insecure_http_allowed(), &self.proxy_env)?;
+        }
         let mut req = self.inner.get(&url);
         if let Some(kp) = &self.keypair {
             let signed = sign_request(kp, "GET", path, b"");
@@ -207,6 +351,9 @@ impl NodeClient {
         proof: Option<&str>,
     ) -> Result<reqwest::Response> {
         let url = format!("{}{}", self.node_url, path);
+        if self.keypair.is_some() {
+            ensure_signing_transport(&self.node_url, insecure_http_allowed(), &self.proxy_env)?;
+        }
         let mut req = self
             .inner
             .request(method.parse().expect("valid HTTP method"), &url)
@@ -1268,4 +1415,224 @@ mod tests {
         let out = sanitize_node_msg("ok \u{0627}\u{200D}b");
         assert_eq!(out, "ok \u{0627}\u{200D}b");
     }
+
+    // ── #413 plaintext-remote signing guard ──────────────────────────────
+
+    /// Holds [`ICAPTCHA_ENV_LOCK`] while it points `GITLAWB_ALLOW_INSECURE_HTTP`
+    /// at `value` (or removes it), restoring the prior value on drop.
+    struct InsecureHttpEnv {
+        _lock: MutexGuard<'static, ()>,
+        prev: Option<OsString>,
+    }
+
+    impl InsecureHttpEnv {
+        fn set(value: Option<&str>) -> Self {
+            let lock = ICAPTCHA_ENV_LOCK.lock().unwrap();
+            let prev = std::env::var_os("GITLAWB_ALLOW_INSECURE_HTTP");
+            match value {
+                Some(v) => std::env::set_var("GITLAWB_ALLOW_INSECURE_HTTP", v),
+                None => std::env::remove_var("GITLAWB_ALLOW_INSECURE_HTTP"),
+            }
+            InsecureHttpEnv { _lock: lock, prev }
+        }
+    }
+
+    impl Drop for InsecureHttpEnv {
+        fn drop(&mut self) {
+            match self.prev.take() {
+                Some(v) => std::env::set_var("GITLAWB_ALLOW_INSECURE_HTTP", v),
+                None => std::env::remove_var("GITLAWB_ALLOW_INSECURE_HTTP"),
+            }
+        }
+    }
+
+    #[test]
+    fn insecure_remote_flags_only_plaintext_off_machine() {
+        // Loopback of every spelling is this machine and exempt.
+        for url in [
+            "http://localhost",
+            "http://localhost:7545",
+            "http://127.0.0.1:7545",
+            "http://127.0.0.2",
+            "http://[::1]",
+            "http://[::ffff:127.0.0.1]",
+            // https to anywhere is encrypted; the guard is not its business.
+            "https://node.gitlawb.com",
+            // Not a URL: unparseable input fails later with its own error.
+            "not a url",
+        ] {
+            assert!(!is_insecure_remote(url), "{url} must not be flagged");
+        }
+        // Plaintext http off this machine is the flagged shape.
+        for url in [
+            "http://10.0.0.36:7777",
+            "http://node.example.com",
+            "http://[fd00::1]",
+            "http://127.0.0.1.evil.example",
+        ] {
+            assert!(is_insecure_remote(url), "{url} must be flagged");
+        }
+    }
+
+    #[test]
+    fn signing_transport_refuses_plaintext_remote() {
+        let no_proxy_env = (false, String::new());
+        let err =
+            ensure_signing_transport("http://10.0.0.36:7777", false, &no_proxy_env).unwrap_err();
+        assert!(
+            err.to_string().contains("plaintext http")
+                && err.to_string().contains("GITLAWB_ALLOW_INSECURE_HTTP"),
+            "the refusal names the risk and the opt-in: {err}"
+        );
+        // Opted in, loopback, and https all pass.
+        assert!(ensure_signing_transport("http://10.0.0.36:7777", true, &no_proxy_env).is_ok());
+        assert!(ensure_signing_transport("http://localhost:7545", false, &no_proxy_env).is_ok());
+        assert!(ensure_signing_transport("https://node.gitlawb.com", false, &no_proxy_env).is_ok());
+    }
+
+    /// A signed call against a plaintext remote errors out before any request
+    /// leaves; the refusal must beat the send. `.invalid` NXDOMAINs fast, so a
+    /// missed guard surfaces as a DNS error rather than a slow timeout.
+    #[tokio::test]
+    async fn get_signed_refuses_plaintext_remote_before_sending() {
+        let _env = InsecureHttpEnv::set(None);
+        let client = NodeClient::new("http://gl-nonexistent-node.invalid", Some(test_keypair()));
+        let err = client.get_signed("/api/v1/x").await.unwrap_err();
+        assert!(
+            err.to_string().contains("plaintext http"),
+            "expected the transport refusal, got: {err}"
+        );
+    }
+
+    /// With the opt-in set, the same call passes the guard and fails later on
+    /// the unresolvable host, proving the env var unblocks the send rather than
+    /// merely being read.
+    #[tokio::test]
+    async fn get_signed_proceeds_when_insecure_http_opted_in() {
+        let _env = InsecureHttpEnv::set(Some("1"));
+        let client = NodeClient::new("http://gl-nonexistent-node.invalid", Some(test_keypair()));
+        let err = client.get_signed("/api/v1/x").await.unwrap_err();
+        assert!(
+            !err.to_string().contains("plaintext http"),
+            "the opt-in should let the request attempt the hop, got: {err}"
+        );
+    }
+
+    /// Unsigned calls are not this guard's business: no keypair means no
+    /// signature to leak, and the request proceeds to its own failure.
+    #[tokio::test]
+    async fn unsigned_call_to_plaintext_remote_is_ungated() {
+        let _env = InsecureHttpEnv::set(None);
+        let client = NodeClient::new("http://gl-nonexistent-node.invalid", None);
+        let err = client.post("/api/v1/x", b"{}").await.unwrap_err();
+        assert!(
+            !err.to_string().contains("plaintext http"),
+            "an unsigned request should not hit the signing guard, got: {err}"
+        );
+    }
+
+    /// The opt-in is presence-based, matching the remote helper's read.
+    #[test]
+    fn insecure_http_allowed_reads_the_env_var() {
+        {
+            let _env = InsecureHttpEnv::set(Some("1"));
+            assert!(insecure_http_allowed());
+        }
+        {
+            let _env = InsecureHttpEnv::set(None);
+            assert!(!insecure_http_allowed());
+        }
+    }
+
+    #[test]
+    fn no_proxy_covers_matches_exact_suffix_and_star() {
+        assert!(no_proxy_covers("localhost", "localhost,127.0.0.1"));
+        assert!(no_proxy_covers("127.0.0.1", "localhost, 127.0.0.1"));
+        assert!(no_proxy_covers("a.example.com", ".example.com"));
+        assert!(no_proxy_covers("a.example.com", "example.com"));
+        assert!(no_proxy_covers("anything", "*"));
+        assert!(!no_proxy_covers("localhost", "127.0.0.1"));
+        assert!(!no_proxy_covers("127.0.0.1", ""));
+        assert!(!no_proxy_covers("notevil.com", "evil.com"));
+    }
+
+    /// Re-exec this test binary running exactly `child_test` under the given
+    /// env, and prove the child actually ran one test rather than filter-
+    /// matching nothing (a wrong `--exact` path exits 0 vacuously).
+    fn run_env_child(child_test: &str, envs: &[(&str, &str)]) {
+        let mut cmd = std::process::Command::new(std::env::current_exe().unwrap());
+        cmd.args(["--exact", child_test, "--nocapture"]);
+        // Clear any inherited proxy state first, then apply the case's env;
+        // env_remove after envs would silently undo a provided NO_PROXY.
+        for k in [
+            "HTTP_PROXY",
+            "http_proxy",
+            "ALL_PROXY",
+            "all_proxy",
+            "NO_PROXY",
+            "no_proxy",
+            "GITLAWB_ALLOW_INSECURE_HTTP",
+        ] {
+            cmd.env_remove(k);
+        }
+        cmd.envs(envs.iter().copied());
+        let out = cmd.output().unwrap();
+        let stdout = String::from_utf8_lossy(&out.stdout);
+        assert!(
+            stdout.contains("1 passed"),
+            "the child must run the test, not exit green on a filter miss. \
+             stdout:\n{stdout}\nstderr:\n{}",
+            String::from_utf8_lossy(&out.stderr)
+        );
+        assert!(
+            out.status.success(),
+            "child failed: {}",
+            String::from_utf8_lossy(&out.stderr)
+        );
+    }
+
+    /// A proxied loopback plaintext hop must be refused. The env plumbing is
+    /// checked in a re-execed child so the process-global proxy vars never
+    /// touch sibling tests' reqwest clients.
+    #[tokio::test]
+    async fn proxied_loopback_http_is_refused() {
+        if std::env::var_os("GL_PROXY_CHILD").is_none() {
+            run_env_child(
+                "http::tests::proxied_loopback_http_is_refused",
+                &[
+                    ("GL_PROXY_CHILD", "1"),
+                    ("HTTP_PROXY", "http://10.9.9.9:3128"),
+                ],
+            );
+            return;
+        }
+        let client = NodeClient::new("http://127.0.0.1:1", Some(test_keypair()));
+        let err = client.get_signed("/api/v1/x").await.unwrap_err();
+        assert!(
+            err.to_string().contains("plaintext http"),
+            "a proxy without NO_PROXY carries the signed request off-machine: {err}"
+        );
+    }
+
+    /// And NO_PROXY covering the host restores the loopback exemption.
+    #[tokio::test]
+    async fn proxied_loopback_with_no_proxy_is_allowed() {
+        if std::env::var_os("GL_PROXY_CHILD2").is_none() {
+            run_env_child(
+                "http::tests::proxied_loopback_with_no_proxy_is_allowed",
+                &[
+                    ("GL_PROXY_CHILD2", "1"),
+                    ("HTTP_PROXY", "http://10.9.9.9:3128"),
+                    ("NO_PROXY", "localhost,127.0.0.1"),
+                ],
+            );
+            return;
+        }
+        let client = NodeClient::new("http://127.0.0.1:1", Some(test_keypair()));
+        let err = client.get_signed("/api/v1/x").await.unwrap_err();
+        assert!(
+            !err.to_string().contains("plaintext http"),
+            "NO_PROXY covering the host keeps the request on this machine: {err}"
+        );
+    }
 }