System.Net.Cache.HttpRequestCacheValidator.FetchHeaderValues C# (CSharp) Method

        private void FetchHeaderValues(bool forCache) {

            WebHeaderCollection cc = forCache? CacheHeaders: Response.Headers;


            FetchCacheControl(cc.CacheControl, forCache);

            // Parse Date Header
            string s = cc.Date;

            DateTime date = DateTime.MinValue;
            if (s != null && HttpDateParse.ParseHttpDate(s, out date)) {
                date = date.ToUniversalTime();
            }
            if (forCache) {
                CacheDate = date;
            }
            else {
                ResponseDate = date;
            }

            // Parse Expires Header
            s = cc.Expires;

            date = DateTime.MinValue;
            if (s != null && HttpDateParse.ParseHttpDate(s, out date)) {
                date = date.ToUniversalTime();
            }
            if (forCache) {
                CacheExpires = date;
            }
            else {
                ResponseExpires = date;
            }

            // Parse LastModified Header
            s = cc.LastModified;

            date = DateTime.MinValue;
            if (s != null && HttpDateParse.ParseHttpDate(s, out date)) {
                date = date.ToUniversalTime();
            }
            if (forCache) {
                CacheLastModified = date;
            }
            else {
                ResponseLastModified = date;
            }

            long totalLength = -1;
            long startRange = -1;
            long end = -1;

            HttpWebResponse resp = Response as HttpWebResponse;
            if ((forCache? CacheStatusCode: resp.StatusCode) != HttpStatusCode.PartialContent) {

                // Parse Content-Length Header
                s = cc.ContentLength;
                if (s != null && s.Length != 0) {
                    int i = 0;
                    char ch = s[0];
                    while (i < s.Length && ch == ' ') {
                        ch = s[++i];
                    }
                    if (i != s.Length && ch >= '0' && ch <= '9') {
                        totalLength = ch-'0';
                        while(++i < s.Length && (ch = s[i]) >= '0' && ch <= '9') {
                            totalLength = totalLength*10+(ch-'0');
                        }
                    }
                }
            }
            else {
                //Parse Content-Range
                s = cc[HttpKnownHeaderNames.ContentRange];
                if(s == null || !Rfc2616.Common.GetBytesRange(s, ref startRange, ref end, ref totalLength, false)) {
                    if(Logging.On)Logging.PrintError(Logging.RequestCache, SR.GetString(SR.net_log_cache_content_range_error, (s==null ? "<null>" : s)));
                    startRange=end=totalLength = -1;
                }
                else if (forCache && totalLength == CacheEntry.StreamSize)
                {
                    // This is a whole response, step back to 200
                    startRange = -1;
                    end = -1;
                    CacheStatusCode = HttpStatusCode.OK;
                    CacheStatusDescription = Rfc2616.Common.OkDescription;
                }
            }

            if (forCache) {
                CacheEntityLength  = totalLength;
                ResponseRangeStart = startRange;
                ResponseRangeEnd   = end;

            }
            else {
                ResponseEntityLength = totalLength;
                ResponseRangeStart = startRange;
                ResponseRangeEnd   = end;
            }

            //Parse Age Header
            TimeSpan span = TimeSpan.MinValue;
            s = cc[HttpKnownHeaderNames.Age];
            if (s != null) {
                int i = 0;
                int sec = 0;
                while(i < s.Length && s[i++] == ' ') {
                    ;
                }
                while(i < s.Length && s[i] >= '0' && s[i] <= '9') {
                    sec = sec*10 + (s[i++] - '0');
                }
                span = TimeSpan.FromSeconds(sec);
            }

            if (forCache) {
                CacheAge = span;
            }
            else {
                ResponseAge = span;
            }
        }