From b13be1e0ce84e7c26a90a8b95d392608d34ca84f Mon Sep 17 00:00:00 2001
From: Sunshine <sunshine@uberspace.net>
Date: Thu, 1 Sep 2022 18:56:30 -0400
Subject: [PATCH] implement domain matching function and adjust tests

---
 src/utils.rs                           | 67 ++++++++++++++++++--------
 tests/utils/domain_is_within_domain.rs | 26 ++++------
 2 files changed, 57 insertions(+), 36 deletions(-)

diff --git a/src/utils.rs b/src/utils.rs
index d88a42f..078a6f0 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -93,33 +93,60 @@ pub fn detect_media_type_by_file_name(filename: &str) -> String {
 }
 
 pub fn domain_is_within_domain(domain: &str, domain_to_match_against: &str) -> bool {
-    let domain_partials: Vec<&str> = domain.split(".").collect();
+    if domain_to_match_against.len() == 0 {
+        return false;
+    }
+
+    if domain_to_match_against == "." {
+        return true;
+    }
+
+    let domain_partials: Vec<&str> = domain.trim_end_matches(".").rsplit(".").collect();
     let domain_to_match_against_partials: Vec<&str> = domain_to_match_against
-        .trim_start_matches(".")
-        .split(".")
+        .trim_end_matches(".")
+        .rsplit(".")
         .collect();
+    let domain_to_match_against_starts_with_a_dot = domain_to_match_against.starts_with(".");
 
-    let mut i: usize = domain_partials.len();
-    let mut j: usize = domain_to_match_against_partials.len();
+    let mut i: usize = 0;
+    let l: usize = std::cmp::max(
+        domain_partials.len(),
+        domain_to_match_against_partials.len(),
+    );
+    let mut ok: bool = true;
 
-    if i >= j {
-        while j > 0 {
-            if !domain_partials
-                .get(i - 1)
-                .unwrap()
-                .eq_ignore_ascii_case(&domain_to_match_against_partials.get(j - 1).unwrap())
-            {
-                break;
-            }
-
-            i -= 1;
-            j -= 1;
+    while i < l {
+        // Exit and return false if went out of bounds of domain to match against, and it didn't start with a dot
+        if domain_to_match_against_partials.len() < i + 1
+            && !domain_to_match_against_starts_with_a_dot
+        {
+            ok = false;
+            break;
         }
 
-        j == 0
-    } else {
-        false
+        let domain_partial = if domain_partials.len() < i + 1 {
+            ""
+        } else {
+            domain_partials.get(i).unwrap()
+        };
+        let domain_to_match_against_partial = if domain_to_match_against_partials.len() < i + 1 {
+            ""
+        } else {
+            domain_to_match_against_partials.get(i).unwrap()
+        };
+
+        let parts_match = domain_to_match_against_starts_with_a_dot
+            || domain_to_match_against_partial.eq_ignore_ascii_case(domain_partial);
+
+        if !parts_match {
+            ok = false;
+            break;
+        }
+
+        i += 1;
     }
+
+    ok
 }
 
 pub fn indent(level: u32) -> String {
diff --git a/tests/utils/domain_is_within_domain.rs b/tests/utils/domain_is_within_domain.rs
index 7eaeae3..fcd0840 100644
--- a/tests/utils/domain_is_within_domain.rs
+++ b/tests/utils/domain_is_within_domain.rs
@@ -25,14 +25,6 @@ mod passing {
         ));
     }
 
-    #[test]
-    fn dotted_domain_is_within_domain() {
-        assert!(utils::domain_is_within_domain(
-            ".ycombinator.com",
-            "ycombinator.com"
-        ));
-    }
-
     #[test]
     fn sub_domain_is_within_dotted_domain() {
         assert!(utils::domain_is_within_domain(
@@ -67,18 +59,12 @@ mod passing {
 
     #[test]
     fn domain_with_trailing_dot_is_within_single_dot() {
-        assert!(utils::domain_is_within_domain(
-            "ycombinator.com.",
-            "."
-        ));
+        assert!(utils::domain_is_within_domain("ycombinator.com.", "."));
     }
 
     #[test]
     fn domain_matches_single_dot() {
-        assert!(utils::domain_is_within_domain(
-            "ycombinator.com",
-            "."
-        ));
+        assert!(utils::domain_is_within_domain("ycombinator.com", "."));
     }
 
     #[test]
@@ -140,6 +126,14 @@ mod failing {
         ));
     }
 
+    #[test]
+    fn dotted_domain_is_not_within_domain() {
+        assert!(!utils::domain_is_within_domain(
+            ".ycombinator.com",
+            "ycombinator.com"
+        ));
+    }
+
     #[test]
     fn no_domain_can_be_within_empty_domain() {
         assert!(!utils::domain_is_within_domain("ycombinator.com", ""));