Improve spec conformance around request header validation (#33418)

* fix: improve spec conformance around request header validation

Signed-off-by: Shane Handley <shanehandley@fastmail.com>

* account for additional test passes

Signed-off-by: Shane Handley <shanehandley@fastmail.com>

* fix: remove redundant .to_vec call

Signed-off-by: Shane Handley <shanehandley@fastmail.com>

---------

Signed-off-by: Shane Handley <shanehandley@fastmail.com>

components/shared/net/fetch/headers.rs

@@ -2,17 +2,185 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use std::iter::Peekable;
+use std::str::Chars;
+
 use headers::HeaderMap;
 
+/// <https://fetch.spec.whatwg.org/#http-tab-or-space>
+const HTTP_TAB_OR_SPACE: &[char] = &['\u{0009}', '\u{0020}'];
+
 /// <https://fetch.spec.whatwg.org/#concept-header-list-get>
 pub fn get_value_from_header_list(name: &str, headers: &HeaderMap) -> Option<Vec<u8>> {
     let values = headers.get_all(name).iter().map(|val| val.as_bytes());
 
-    // Step 1
+    // Step 1: If list does not contain name, then return null.
     if values.size_hint() == (0, Some(0)) {
         return None;
     }
 
-    // Step 2
+    // Step 2: Return the values of all headers in list whose name is a byte-case-insensitive match
+    // for name, separated from each other by 0x2C 0x20, in order.
     Some(values.collect::<Vec<&[u8]>>().join(&[0x2C, 0x20][..]))
 }
+
+/// <https://fetch.spec.whatwg.org/#forbidden-method>
+pub fn is_forbidden_method(method: &[u8]) -> bool {
+    matches!(
+        method.to_ascii_lowercase().as_slice(),
+        b"connect" | b"trace" | b"track"
+    )
+}
+
+/// <https://fetch.spec.whatwg.org/#concept-header-list-get-decode-split>
+pub fn get_decode_and_split_header_name(name: &str, headers: &HeaderMap) -> Option<Vec<String>> {
+    // Step 1: Let value be the result of getting name from list.
+    // Step 2: If value is null, then return null.
+    // Step 3: Return the result of getting, decoding, and splitting value.
+    get_value_from_header_list(name, headers).map(|value| get_decode_and_split_header_value(value))
+}
+
+/// <https://fetch.spec.whatwg.org/#header-value-get-decode-and-split>
+pub fn get_decode_and_split_header_value(value: Vec<u8>) -> Vec<String> {
+    fn char_is_not_quote_or_comma(c: char) -> bool {
+        c != '\u{0022}' && c != '\u{002C}'
+    }
+
+    // Step 1: Let input be the result of isomorphic decoding value.
+    let input = value.into_iter().map(char::from).collect::<String>();
+
+    // Step 2: Let position be a position variable for input, initially pointing at the start of
+    // input.
+    let mut position = input.chars().peekable();
+
+    // Step 3: Let values be a list of strings, initially « ».
+    let mut values: Vec<String> = vec![];
+
+    // Step 4: Let temporaryValue be the empty string.
+    let mut temporary_value = String::new();
+
+    // Step 5: While true:
+    while position.peek().is_some() {
+        // Step 5.1: Append the result of collecting a sequence of code points that are not U+0022
+        // (") or U+002C (,) from input, given position, to temporaryValue.
+        temporary_value += &*collect_sequence(&mut position, char_is_not_quote_or_comma);
+
+        // Step 5.2: If position is not past the end of input and the code point at position within
+        // input is U+0022 ("):
+        if let Some(&ch) = position.peek() {
+            if ch == '\u{0022}' {
+                // Step 5.2.1: Append the result of collecting an HTTP quoted string from input,
+                // given position, to temporaryValue.
+                temporary_value += &*collect_http_quoted_string(&mut position, false);
+
+                // Step 5.2.2: If position is not past the end of input, then continue.
+                if position.peek().is_some() {
+                    continue;
+                }
+            } else {
+                // Step 5.2.2: If position is not past the end of input, then continue.
+                position.next();
+            }
+        }
+
+        // Step 5.3: Remove all HTTP tab or space from the start and end of temporaryValue.
+        temporary_value = temporary_value.trim_matches(HTTP_TAB_OR_SPACE).to_string();
+
+        // Step 5.4: Append temporaryValue to values.
+        values.push(temporary_value);
+
+        // Step 5.5: Set temporaryValue to the empty string.
+        temporary_value = String::new();
+    }
+
+    return values;
+}
+
+/// <https://infra.spec.whatwg.org/#collect-a-sequence-of-code-points>
+fn collect_sequence<F>(position: &mut Peekable<Chars>, condition: F) -> String
+where
+    F: Fn(char) -> bool,
+{
+    // Step 1: Let result be the empty string.
+    let mut result = String::new();
+
+    // Step 2: While position doesn’t point past the end of input and the code point at position
+    // within input meets the condition condition:
+    while let Some(&ch) = position.peek() {
+        if !condition(ch) {
+            break;
+        }
+
+        // Step 2.1: Append that code point to the end of result.
+        result.push(ch);
+
+        // Step 2.2: Advance position by 1.
+        position.next();
+    }
+
+    // Step 3: Return result.
+    result
+}
+
+/// <https://fetch.spec.whatwg.org/#collect-an-http-quoted-string>
+fn collect_http_quoted_string(position: &mut Peekable<Chars>, extract_value: bool) -> String {
+    fn char_is_not_quote_or_backslash(c: char) -> bool {
+        c != '\u{0022}' && c != '\u{005C}'
+    }
+
+    // Step 2: let value be the empty string
+    // We will store the 'extracted value' or the raw value
+    let mut value = String::new();
+
+    // Step 3, 4
+    let should_be_quote = position.next();
+    if let Some(ch) = should_be_quote {
+        if !extract_value {
+            value.push(ch)
+        }
+    }
+
+    // Step 5: While true:
+    loop {
+        // Step 5.1: Append the result of collecting a sequence of code points that are not U+0022
+        // (") or U+005C (\) from input, given position, to value.
+        value += &*collect_sequence(position, char_is_not_quote_or_backslash);
+
+        // Step 5.2: If position is past the end of input, then break.
+        if position.peek().is_none() {
+            break;
+        }
+
+        // Step 5.3: Let quoteOrBackslash be the code point at position within input.
+        // Step 5.4: Advance position by 1.
+        let quote_or_backslash = position.next().unwrap();
+
+        if !extract_value {
+            value.push(quote_or_backslash);
+        }
+
+        // Step 5.5: If quoteOrBackslash is U+005C (\), then:
+        if quote_or_backslash == '\u{005C}' {
+            if let Some(ch) = position.next() {
+                // Step 5.5.2: Append the code point at position within input to value.
+                value.push(ch);
+            } else {
+                // Step 5.5.1: If position is past the end of input, then append U+005C (\) to value and break.
+                if extract_value {
+                    value.push('\u{005C}');
+                }
+
+                break;
+            }
+        } else {
+            // Step 5.6.1: Assert quote_or_backslash is a quote
+            assert_eq!(quote_or_backslash, '\u{0022}');
+
+            // Step 5.6.2: break
+            break;
+        }
+    }
+
+    // Step 6, 7
+    value
+}