fix: remove dependency on node's _http_common module (#114)

* fix: remove dependency on node's `_http_common` module

The checks is `isInvalidHeader` method are now backported from node's source.
Both methods were just a regexp checks, so it was trivial to use the very same
logic as in node.

The implementation changed a bit, `checkInvalidHeaderChar` is now implemented via regexp check,
and the `validateHeader` method was split into `validateHeaderName` and `validateHeaderValue`.

Both regexps are taken from the latest code from master. Also verified the exiting test in node,
but they seem to be aligned with the existing test suite (added only one additional assertion
for `undefined`).

Closes #50

* refactor: do not export internal helper methods

Author: B4nan

src/tools.js

@@ -1,5 +1,3 @@
-import { _checkIsHttpToken, _checkInvalidHeaderChar } from '_http_common'; // eslint-disable-line
-
 const HOST_HEADER_REGEX = /^((([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9-]*[A-Za-z0-9]))(:([0-9]+))?$/;
 
 /**
@@ -42,15 +40,35 @@ const HOP_BY_HOP_HEADERS_REGEX = new RegExp(`^(${HOP_BY_HOP_HEADERS.join('|')})$
 
 export const isHopByHopHeader = (header) => HOP_BY_HOP_HEADERS_REGEX.test(header);
 
+const TOKEN_REGEX = /^[\^_`a-zA-Z\-0-9!#$%&'*+.|~]+$/;
+
+/**
+ * Verifies that the given val is a valid HTTP token per the rules defined in RFC 7230
+ * @see https://tools.ietf.org/html/rfc7230#section-3.2.6
+ * @see https://github.com/nodejs/node/blob/8cf5ae07e9e80747c19e0fc04fad48423707f62c/lib/_http_common.js#L222
+ */
+const isHttpToken = (val) => TOKEN_REGEX.test(val);
+
+const HEADER_CHAR_REGEX = /[^\t\x20-\x7e\x80-\xff]/;
+
+/**
+ * True if val contains an invalid field-vchar
+ *  field-value    = *( field-content / obs-fold )
+ *  field-content  = field-vchar [ 1*( SP / HTAB ) field-vchar ]
+ *  field-vchar    = VCHAR / obs-text
+ * @see https://github.com/nodejs/node/blob/8cf5ae07e9e80747c19e0fc04fad48423707f62c/lib/_http_common.js#L233
+ */
+const isInvalidHeaderChar = (val) => HEADER_CHAR_REGEX.test(val);
+
 // This code is based on Node.js' validateHeader() function from _http_outgoing.js module
 // (see https://github.com/nodejs/node/blob/189d29f39e6de9ccf10682bfd1341819b4a2291f/lib/_http_outgoing.js#L485)
 export const isInvalidHeader = (name, value) => {
     // NOTE: These are internal Node.js functions, they might stop working in the future!
     return typeof name !== 'string'
         || !name
-        || !_checkIsHttpToken(name)
+        || !isHttpToken(name)
         || value === undefined
-        || _checkInvalidHeaderChar(value);
+        || isInvalidHeaderChar(value);
 };
 
 const bulletproofDecodeURIComponent = (encodedURIComponent) => {

test/tools.js

@@ -261,6 +261,7 @@ describe('tools.isInvalidHeader()', () => {
     it('works', () => {
         expect(isInvalidHeader('With space', 'a')).to.eql(true);
         expect(isInvalidHeader('', 'a')).to.eql(true);
+        expect(isInvalidHeader(undefined, 'a')).to.eql(true);
         expect(isInvalidHeader(null, 'a')).to.eql(true);
         expect(isInvalidHeader(1234, 'a')).to.eql(true);
         expect(isInvalidHeader('\n', 'a')).to.eql(true);