🛡️ Sentinel: Harden SSRF protection and add security tests by abhimehro · Pull Request #145 · abhimehro/ctrld-sync

abhimehro · 2026-01-30T10:53:22Z

Removed @lru_cache from validate_folder_url in main.py to mitigate TOCTOU (Time-of-Check Time-of-Use) vulnerabilities where DNS records could change between validation and fetch.

Added comprehensive tests in tests/test_security.py (merged with existing tests) to verify:

HTTPS enforcement
Rejection of private/loopback IPs (IPv4/IPv6)
Blocking of localhost
Safe handling of DNS failures

This ensures the SSRF protection mechanism is robust and verified by CI.

PR created automatically by Jules for task 13165274204186978288 started by @abhimehro

Co-authored-by: abhimehro <84992105+abhimehro@users.noreply.github.com>

google-labs-jules · 2026-01-30T10:53:23Z

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trunk-io · 2026-01-30T10:53:25Z

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gemini-code-assist · 2026-01-30T10:53:36Z

Summary of Changes

Hello @abhimehro, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly hardens the SSRF protection mechanism by eliminating a potential TOCTOU vulnerability related to DNS caching and by introducing a robust suite of security tests. The changes ensure that URL validations are always performed immediately before use, preventing malicious DNS record changes from being exploited, and that the system correctly blocks various forms of unauthorized access attempts.

Highlights

TOCTOU Vulnerability Mitigation: The @lru_cache decorator was removed from the validate_folder_url function in main.py to prevent Time-of-Check Time-of-Use (TOCTOU) vulnerabilities, specifically DNS rebinding attacks, by ensuring validation occurs immediately before use.
Enhanced Security Testing: Comprehensive security tests have been added to tests/test_security.py to rigorously verify the validate_folder_url function's SSRF protection. These tests cover HTTPS enforcement, rejection of private/loopback IPs (both resolved and literal), and safe handling of DNS failures.

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tests/test_security.py

+    """Security tests for SSRF protection in validate_folder_url."""
+
+    def test_rejects_non_https(self):
+        assert main.validate_folder_url("http://example.com/foo") is False


tests/test_security.py

+
+    def test_rejects_non_https(self):
+        assert main.validate_folder_url("http://example.com/foo") is False
+        assert main.validate_folder_url("ftp://example.com/foo") is False


tests/test_security.py

+    def test_rejects_non_https(self):
+        assert main.validate_folder_url("http://example.com/foo") is False
+        assert main.validate_folder_url("ftp://example.com/foo") is False
+        assert main.validate_folder_url("file:///etc/passwd") is False


tests/test_security.py

+    def test_accepts_valid_public_ip(self, mock_gai):
+        # Mock domain resolving to public IP (8.8.8.8)
+        mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv4("8.8.8.8")
+        assert main.validate_folder_url("https://example.com/foo") is True


tests/test_security.py

+
+    def test_rejects_localhost_literal(self):
+        # Test explicit localhost hostname check
+        assert main.validate_folder_url("https://localhost/foo") is False


tests/test_security.py

+        # IP literals are checked directly via ipaddress module, bypassing DNS
+        assert main.validate_folder_url("https://192.168.1.1/foo") is False
+        assert main.validate_folder_url("https://10.0.0.1/foo") is False
+        assert main.validate_folder_url("https://127.0.0.1/foo") is False


tests/test_security.py

+        assert main.validate_folder_url("https://192.168.1.1/foo") is False
+        assert main.validate_folder_url("https://10.0.0.1/foo") is False
+        assert main.validate_folder_url("https://127.0.0.1/foo") is False
+        assert main.validate_folder_url("https://[::1]/foo") is False


tests/test_security.py

+        assert main.validate_folder_url("https://[::1]/foo") is False
+
+    def test_accepts_ip_literal_public(self):
+        assert main.validate_folder_url("https://8.8.8.8/foo") is True


tests/test_security.py

+
+    def test_accepts_ip_literal_public(self):
+        assert main.validate_folder_url("https://8.8.8.8/foo") is True
+        assert main.validate_folder_url("https://[2001:4860:4860::8888]/foo") is True


tests/test_security.py

+    def test_dns_resolution_failure_is_safe(self, mock_gai):
+        # Ensure that if DNS fails, we default to False (fail closed)
+        mock_gai.side_effect = socket.gaierror("Name or service not known")
+        assert main.validate_folder_url("https://nonexistent.com/foo") is False


gemini-code-assist

Code Review

This pull request effectively hardens the application against Server-Side Request Forgery (SSRF) attacks by removing caching from the URL validation logic, which mitigates a Time-of-Check Time-of-Use (TOCTOU) vulnerability. The changes in main.py are correct and well-commented. The addition of a comprehensive security test suite in tests/test_security.py is a significant improvement, ensuring the SSRF protections are robust and verifiable. My review includes a few suggestions to further improve the new tests by using parametrization, which will enhance their readability and maintainability.

gemini-code-assist · 2026-01-30T10:54:49Z

tests/test_security.py

+    def test_rejects_non_https(self):
+        assert main.validate_folder_url("http://example.com/foo") is False
+        assert main.validate_folder_url("ftp://example.com/foo") is False
+        assert main.validate_folder_url("file:///etc/passwd") is False


This test can be made more concise and easier to extend by using pytest.mark.parametrize. This converts multiple assertions into a data-driven test, which is cleaner and provides better failure messages for individual cases.

Suggested change

def test_rejects_non_https(self):

assert main.validate_folder_url("http://example.com/foo") is False

assert main.validate_folder_url("ftp://example.com/foo") is False

assert main.validate_folder_url("file:///etc/passwd") is False

@pytest.mark.parametrize("url", [

"http://example.com/foo",

"ftp://example.com/foo",

"file:///etc/passwd",

])

def test_rejects_non_https(self, url):

assert main.validate_folder_url(url) is False

gemini-code-assist · 2026-01-30T10:54:49Z

tests/test_security.py

+    @patch('socket.getaddrinfo')
+    def test_accepts_valid_public_ip(self, mock_gai):
+        # Mock domain resolving to public IP (8.8.8.8)
+        mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv4("8.8.8.8")


For a mock that should always return the same value regardless of arguments, using return_value is simpler and more direct than side_effect with a lambda. This improves readability.

Suggested change

mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv4("8.8.8.8")

mock_gai.return_value = mock_getaddrinfo_ipv4("8.8.8.8")

gemini-code-assist · 2026-01-30T10:54:49Z

tests/test_security.py

+    @patch('socket.getaddrinfo')
+    def test_rejects_private_ip_resolution(self, mock_gai):
+        # Mock domain resolving to private IP (192.168.1.1)
+        mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv4("192.168.1.1")
+        assert main.validate_folder_url("https://internal.corp/foo") is False
+
+    @patch('socket.getaddrinfo')
+    def test_rejects_loopback_ip_resolution(self, mock_gai):
+        # Mock domain resolving to loopback IP (127.0.0.1)
+        mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv4("127.0.0.1")
+        assert main.validate_folder_url("https://evil.com/foo") is False
+
+    @patch('socket.getaddrinfo')
+    def test_rejects_ipv6_loopback_resolution(self, mock_gai):
+        # Mock domain resolving to IPv6 loopback (::1)
+        mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv6("::1")
+        assert main.validate_folder_url("https://ipv6.local/foo") is False


The tests for private, loopback, and IPv6 loopback resolutions are very similar. They can be combined into a single, parametrized test. This reduces code duplication and makes the test suite easier to maintain and extend with more non-public IP cases in the future. This suggestion also simplifies the mock setup by using return_value instead of a side_effect with a lambda, which is more direct for this use case.

Suggested change

@patch('socket.getaddrinfo')

def test_rejects_private_ip_resolution(self, mock_gai):

# Mock domain resolving to private IP (192.168.1.1)

mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv4("192.168.1.1")

assert main.validate_folder_url("https://internal.corp/foo") is False

@patch('socket.getaddrinfo')

def test_rejects_loopback_ip_resolution(self, mock_gai):

# Mock domain resolving to loopback IP (127.0.0.1)

mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv4("127.0.0.1")

assert main.validate_folder_url("https://evil.com/foo") is False

@patch('socket.getaddrinfo')

def test_rejects_ipv6_loopback_resolution(self, mock_gai):

# Mock domain resolving to IPv6 loopback (::1)

mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv6("::1")

assert main.validate_folder_url("https://ipv6.local/foo") is False

@pytest.mark.parametrize("ip, mock_fn, url", [

("192.168.1.1", mock_getaddrinfo_ipv4, "https://internal.corp/foo"),

("127.0.0.1", mock_getaddrinfo_ipv4, "https://evil.com/foo"),

("::1", mock_getaddrinfo_ipv6, "https://ipv6.local/foo"),

])

@patch('socket.getaddrinfo')

def test_rejects_non_public_ip_resolution(self, mock_gai, ip, mock_fn, url):

"""Tests that domains resolving to private or loopback IPs are rejected."""

mock_gai.return_value = mock_fn(ip)

assert main.validate_folder_url(url) is False

gemini-code-assist · 2026-01-30T10:54:49Z

tests/test_security.py

+    def test_rejects_ip_literal_private(self):
+        # IP literals are checked directly via ipaddress module, bypassing DNS
+        assert main.validate_folder_url("https://192.168.1.1/foo") is False
+        assert main.validate_folder_url("https://10.0.0.1/foo") is False
+        assert main.validate_folder_url("https://127.0.0.1/foo") is False
+        assert main.validate_folder_url("https://[::1]/foo") is False


This test can be made more concise and easier to extend by using pytest.mark.parametrize. This converts multiple assertions into a data-driven test, which is cleaner and provides better failure messages for individual cases.

Suggested change

def test_rejects_ip_literal_private(self):

# IP literals are checked directly via ipaddress module, bypassing DNS

assert main.validate_folder_url("https://192.168.1.1/foo") is False

assert main.validate_folder_url("https://10.0.0.1/foo") is False

assert main.validate_folder_url("https://127.0.0.1/foo") is False

assert main.validate_folder_url("https://[::1]/foo") is False

@pytest.mark.parametrize("url", [

"https://192.168.1.1/foo",

"https://10.0.0.1/foo",

"https://127.0.0.1/foo",

"https://[::1]/foo",

])

def test_rejects_ip_literal_private(self, url):

# IP literals are checked directly via ipaddress module, bypassing DNS

assert main.validate_folder_url(url) is False

gemini-code-assist · 2026-01-30T10:54:49Z

tests/test_security.py

+    def test_accepts_ip_literal_public(self):
+        assert main.validate_folder_url("https://8.8.8.8/foo") is True
+        assert main.validate_folder_url("https://[2001:4860:4860::8888]/foo") is True


This test can be made more concise and easier to extend by using pytest.mark.parametrize. This converts multiple assertions into a data-driven test.

Suggested change

def test_accepts_ip_literal_public(self):

assert main.validate_folder_url("https://8.8.8.8/foo") is True

assert main.validate_folder_url("https://[2001:4860:4860::8888]/foo") is True

@pytest.mark.parametrize("url", [

"https://8.8.8.8/foo",

"https://[2001:4860:4860::8888]/foo",

])

def test_accepts_ip_literal_public(self, url):

assert main.validate_folder_url(url) is True

github-advanced-security

Pylintpython3 (reported by Codacy) found more than 20 potential problems in the proposed changes. Check the Files changed tab for more details.

github-advanced-security

Pylint (reported by Codacy) found more than 20 potential problems in the proposed changes. Check the Files changed tab for more details.

tests/test_security.py

+    """Security tests for SSRF protection in validate_folder_url."""
+
+    def test_rejects_non_https(self):
+        assert main.validate_folder_url("http://example.com/foo") is False


tests/test_security.py

+
+    def test_rejects_non_https(self):
+        assert main.validate_folder_url("http://example.com/foo") is False
+        assert main.validate_folder_url("ftp://example.com/foo") is False


tests/test_security.py

+    def test_rejects_non_https(self):
+        assert main.validate_folder_url("http://example.com/foo") is False
+        assert main.validate_folder_url("ftp://example.com/foo") is False
+        assert main.validate_folder_url("file:///etc/passwd") is False


tests/test_security.py

+    def test_accepts_valid_public_ip(self, mock_gai):
+        # Mock domain resolving to public IP (8.8.8.8)
+        mock_gai.side_effect = lambda host, *args, **kwargs: mock_getaddrinfo_ipv4("8.8.8.8")
+        assert main.validate_folder_url("https://example.com/foo") is True


tests/test_security.py

+
+    def test_rejects_localhost_literal(self):
+        # Test explicit localhost hostname check
+        assert main.validate_folder_url("https://localhost/foo") is False


tests/test_security.py

+        # IP literals are checked directly via ipaddress module, bypassing DNS
+        assert main.validate_folder_url("https://192.168.1.1/foo") is False
+        assert main.validate_folder_url("https://10.0.0.1/foo") is False
+        assert main.validate_folder_url("https://127.0.0.1/foo") is False


tests/test_security.py

+        assert main.validate_folder_url("https://192.168.1.1/foo") is False
+        assert main.validate_folder_url("https://10.0.0.1/foo") is False
+        assert main.validate_folder_url("https://127.0.0.1/foo") is False
+        assert main.validate_folder_url("https://[::1]/foo") is False


tests/test_security.py

+        assert main.validate_folder_url("https://[::1]/foo") is False
+
+    def test_accepts_ip_literal_public(self):
+        assert main.validate_folder_url("https://8.8.8.8/foo") is True


tests/test_security.py

+
+    def test_accepts_ip_literal_public(self):
+        assert main.validate_folder_url("https://8.8.8.8/foo") is True
+        assert main.validate_folder_url("https://[2001:4860:4860::8888]/foo") is True


tests/test_security.py

+    def test_dns_resolution_failure_is_safe(self, mock_gai):
+        # Ensure that if DNS fails, we default to False (fail closed)
+        mock_gai.side_effect = socket.gaierror("Name or service not known")
+        assert main.validate_folder_url("https://nonexistent.com/foo") is False


Copilot

Pull request overview

This PR strengthens SSRF (Server-Side Request Forgery) protection by removing the @lru_cache decorator from validate_folder_url to eliminate TOCTOU (Time-of-Check Time-of-Use) vulnerabilities arising from DNS rebinding attacks. The change ensures DNS resolution happens at validation time rather than using potentially stale cached results. Comprehensive security tests are added to verify the SSRF protection mechanisms.

Changes:

Removed @lru_cache decorator and import to prevent caching of validation results
Updated security comments explaining TOCTOU/DNS rebinding risks
Added comprehensive test suite covering HTTPS enforcement, private/loopback IP rejection (IPv4/IPv6), public IP acceptance, and DNS failure handling

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
main.py	Removed `lru_cache` import, decorator, and cache clearing; added security comments explaining TOCTOU mitigation
tests/test_security.py	Added comprehensive SSRF protection tests including protocol validation, IP address checks, DNS resolution scenarios, and failure handling

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Copilot · 2026-01-30T10:57:55Z

main.py

+    # SECURITY: Removed cache clearing because we removed the cache on validate_folder_url
+    # to mitigate TOCTOU (DNS Rebinding) risks. Validation now happens per-fetch.


The comment states "Validation now happens per-fetch" but this is not entirely accurate. Looking at the _fetch_if_valid function below (lines 1058-1060), URLs that are already in the data cache (_cache) are returned directly without re-validation. This means validation does not happen per-fetch for cached URLs, which could still present a TOCTOU risk if DNS records change between syncs within the same process. Consider updating the comment to clarify that validation happens per-fetch for non-cached URLs, or document the accepted risk of using cached data without re-validation.

…itization, add dry-run plan details Incorporates the best changes from 36 Jules PRs, addressing review feedback: Bolt (Performance) - from PR #173: - Pre-compile PROFILE_ID_PATTERN and RULE_PATTERN at module level - Use compiled patterns in is_valid_profile_id_format, validate_profile_id, and is_valid_rule - Supersedes PRs: #140, #143, #152, #155, #158, #161, #167, #170, #173 Sentinel (Security) - from PR #172 with review feedback: - Enhance sanitize_for_log to redact Basic Auth credentials in URLs - Redact sensitive query parameters (token, key, secret, password, etc.) - Handle fragment separators (#) per Gemini Code Assist review - Use [^&#\s]* pattern per Copilot reviewer suggestion - Update docstring per reviewer suggestion - Supersedes PRs: #142, #145, #148, #151, #154, #157, #160, #169, #172 Palette (UX) - from PR #174 with lint fixes: - Add print_plan_details function for dry-run visibility - Fix duplicate render_progress_bar definition bug - Supersedes PRs: #139, #141, #144, #147, #150, #153, #156, #159, #162, #165, #168, #171, #174 Also: #146, #149, #164 (parallel folder deletion) and #166 (auto-fix .env perms) are independent features not consolidated here. Co-authored-by: abhimehro <84992105+abhimehro@users.noreply.github.com>

Harden SSRF protection and add security tests

27553d8

Co-authored-by: abhimehro <84992105+abhimehro@users.noreply.github.com>

Copilot AI review requested due to automatic review settings January 30, 2026 10:53

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Copilot started reviewing on behalf of abhimehro January 30, 2026 10:53 View session

github-advanced-security bot found potential problems Jan 30, 2026

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Copilot AI mentioned this pull request Feb 8, 2026

Consolidate 36 Jules PRs: pre-compile regex, harden log sanitization, add dry-run plan details #175

Merged

abhimehro closed this Feb 9, 2026

abhimehro deleted the sentinel-ssrf-hardening-13165274204186978288 branch February 9, 2026 00:18

-    def test_rejects_non_https(self):
-        assert main.validate_folder_url("http://example.com/foo") is False
-        assert main.validate_folder_url("ftp://example.com/foo") is False
-        assert main.validate_folder_url("file:///etc/passwd") is False
+    @pytest.mark.parametrize("url", [
+        "http://example.com/foo",
+        "ftp://example.com/foo",
+        "file:///etc/passwd",
+    ])
+    def test_rejects_non_https(self, url):
+        assert main.validate_folder_url(url) is False

	mock_gai.side_effect = lambda host, args, *kwargs: mock_getaddrinfo_ipv4("8.8.8.8")
	mock_gai.return_value = mock_getaddrinfo_ipv4("8.8.8.8")

		# SECURITY: Removed cache clearing because we removed the cache on validate_folder_url
		# to mitigate TOCTOU (DNS Rebinding) risks. Validation now happens per-fetch.

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