fixup! ACME: alternative chains support.

Author: bavshin-f5

src/acme/headers.rs

@@ -35,6 +35,8 @@ impl<'a> Iterator for LinkIter<'a> {
     type Item = Link<'a>;
 
     fn next(&mut self) -> Option<Self::Item> {
+        // Link       = [ ( "," / link-value ) *( OWS "," [ OWS link-value ] ) ]
+
         // link-value = "<" URI-Reference ">" *( OWS ";" OWS link-param )
         fn consume_link_value(p: &str) -> Option<(Link<'_>, &str)> {
             let p = p.trim_ascii_start().strip_prefix('<')?;
@@ -65,6 +67,12 @@ impl<'a> Iterator for LinkIter<'a> {
                 let value;
                 (name, value, p) = consume_link_param(p)?;
 
+                // 9.   Let relations_string be the second item of the first tuple
+                //      of link_parameters whose first item matches the string "rel"
+                //      or the empty string ("") if it is not present.
+                // 10.  Split relations_string on RWS (removing it in the process)
+                //      into a list of string relation_types.
+
                 if rel.is_empty() && name.eq_ignore_ascii_case("rel") {
                     rel.extend(value.split_ascii_whitespace());
                 }
@@ -106,7 +114,7 @@ impl<'a> Iterator for LinkIter<'a> {
 
             for (i, c) in p.char_indices() {
                 if c == '\\' {
-                    escape = true;
+                    escape = !escape;
                 } else if c == '"' && !escape {
                     let (head, tail) = p.split_at(i);
                     return Some((head, tail.strip_prefix('"')?));
@@ -115,11 +123,16 @@ impl<'a> Iterator for LinkIter<'a> {
                 }
             }
 
-            None
+            Some((p, ""))
         }
 
         let link;
 
+        self.0 = self.0.trim_ascii_start();
+        while let Some(p) = self.0.strip_prefix(',') {
+            self.0 = p.trim_ascii_start();
+        }
+
         (link, self.0) = consume_link_value(self.0)?;
 
         Some(link)
@@ -187,10 +200,24 @@ mod tests {
                 &[("test", &["alternate"])],
             ),
             (
-                // spaces and other parser sanity checks
-                " <https://example.com/acme/directory> ;\t foo=\";,=<>\"; rel = \"index\"\t",
+                // spaces, commas and other parser sanity checks
+                concat!(
+                    " , <https://example.com/acme/directory> ;\t foo=\";,=<>\"; rel = \"index\"\t,  ,,, ",
+                    " , <https://example.com/acme/directory> ;\t foo=\";,=<>\"; rel = \"index\"\t,  ,,, "
+                ),
+                &[
+                    ("https://example.com/acme/directory", &["index"]),
+                    ("https://example.com/acme/directory", &["index"])
+                ],
+            ),
+            (
+                "<https://example.com/acme/directory>;rel=\"index",
                 &[("https://example.com/acme/directory", &["index"])],
             ),
+            (
+                r#"<https://example.com/acme/directory>;rel="index\""#,
+                &[("https://example.com/acme/directory", &["index\\\""])],
+            ),
             (
                 // multiple link-values
                 concat!(