Add ability to also retrieve only specific headers and a body in addition to all headers and a body

lib/imap.js

@@ -239,6 +239,9 @@ ImapConnection.prototype.connect = function(loginCb) {
               state.parser = new MIMEParser();
               state.parser.on('header', function(name, val) {
                 name = name.toLowerCase();
+                if (requests[0]._headers
+                    && requests[0]._headers.indexOf(name) === -1)
+                  return;
                 if (requests[0]._msg.headers[name] !== undefined)
                   requests[0]._msg.headers[name].push(val);
                 else
@@ -799,13 +802,12 @@ ImapConnection.prototype._fetch = function(which, uids, options) {
       headers: true,
       body: false
     }
-  }, toFetch, bodyRange, extensions, useParser, self = this;
+  }, toFetch, bodyRange, extensions, useParser, onlyHeaders, self = this;
 
   if (typeof options !== 'object')
     options = {};
   utils.extend(true, opts, options);
 
-  if (!Array.isArray(opts.request.headers)) {
     if (Array.isArray(opts.request.body)) {
       var rangeInfo;
       if (opts.request.body.length !== 2)
@@ -818,13 +820,20 @@ ImapConnection.prototype._fetch = function(which, uids, options) {
                   + parseInt(rangeInfo[2], 10) + '>';
       opts.request.body = opts.request.body[0];
     }
-    if (opts.request.headers === true && opts.request.body === true) {
-      // fetches the whole entire message (including the headers)
-      toFetch = '';
-      useParser = true;
-    } else if (opts.request.headers === true) {
-      // fetches headers only
-      toFetch = 'HEADER';
+    if (opts.request.headers !== false
+        && typeof opts.request.body === 'boolean') {
+      if (Array.isArray(opts.request.headers))
+        onlyHeaders = opts.request.headers.join(' ').toUpperCase();
+      if (opts.request.body === true) {
+        // fetches the whole entire message (including some/all headers)
+        toFetch = '';
+      } else if (onlyHeaders) {
+        // fetch specific headers only
+        toFetch = 'HEADER.FIELDS (' + onlyHeaders + ')';
+      } else {
+        // fetches (all) headers only
+        toFetch = 'HEADER';
+      }
       useParser = true;
     } else if (opts.request.body === true) {
       // fetches the whole entire message text (minus the headers), including
@@ -841,12 +850,6 @@ ImapConnection.prototype._fetch = function(which, uids, options) {
       } else
         throw new Error("Invalid body partID format");
     }
-  } else {
-    // fetch specific headers only
-    toFetch = 'HEADER.FIELDS (' + opts.request.headers.join(' ').toUpperCase()
-              + ')';
-    useParser = true;
-  }
 
   // always fetch GMail-specific bits of information when on GMail
   if (this._serverSupports('X-GM-EXT-1'))
@@ -885,6 +888,8 @@ ImapConnection.prototype._fetch = function(which, uids, options) {
       req = this._state.requests[this._state.requests.length - 1];
   req._fetcher = imapFetcher;
   req._useParser = useParser;
+  if (Array.isArray(opts.request.headers))
+    req._headers = onlyHeaders.toLowerCase().split(' ');
   return imapFetcher;
 };