public static CacheControl getCacheControl(IHttpHeaders headers, long requestTime)
{
CacheControl cc=new CacheControl();
bool proxyRevalidate=false;
int sMaxAge=0;
bool publicCache=false;
bool privateCache=false;
bool noCache=false;
long expires=0;
bool hasExpires=false;
cc.uri=headers.getUrl();
string cacheControl=headers.getHeaderField("cache-control");
if(cacheControl!=null){
int index=0;
int[] intval=new int[1];
while(index<cacheControl.Length){
int current=index;
if((index=HeaderParser.parseToken(cacheControl,current,"private",true))!=current){
privateCache=true;
} else if((index=HeaderParser.parseToken(cacheControl,current,"no-cache",true))!=current){
noCache=true;
//Console.WriteLine("returning early because it saw no-cache");
return null; // return immediately, this is not cacheable
} else if((index=HeaderParser.parseToken(
cacheControl,current,"no-store",false))!=current){
cc.noStore=true;
//Console.WriteLine("returning early because it saw no-store");
return null; // return immediately, this is not cacheable or storable
} else if((index=HeaderParser.parseToken(
cacheControl,current,"public",false))!=current){
publicCache=true;
} else if((index=HeaderParser.parseToken(
cacheControl,current,"no-transform",false))!=current){
cc.noTransform=true;
} else if((index=HeaderParser.parseToken(
cacheControl,current,"must-revalidate",false))!=current){
cc.mustRevalidate=true;
} else if((index=HeaderParser.parseToken(
cacheControl,current,"proxy-revalidate",false))!=current){
proxyRevalidate=true;
} else if((index=HeaderParser.parseTokenWithDelta(
cacheControl,current,"max-age",intval))!=current){
cc.maxAge=intval[0];
} else if((index=HeaderParser.parseTokenWithDelta(
cacheControl,current,"s-maxage",intval))!=current){
sMaxAge=intval[0];
} else {
index=HeaderParser.skipDirective(cacheControl,current);
}
}
if(!publicCache && !privateCache && !noCache){
noCache=true;
}
} else {
int code=headers.getResponseCode();
if((code==200 || code==203 || code==300 || code==301 || code==410) &&
headers.getHeaderField("authorization")==null){
publicCache=true;
privateCache=false;
} else {
noCache=true;
}
}
if(headers.getResponseCode()==206) {
noCache=true;
}
string pragma=headers.getHeaderField("pragma");
if(pragma!=null && "no-cache".Equals(StringUtility.toLowerCaseAscii(pragma))){
noCache=true;
//Console.WriteLine("returning early because it saw pragma no-cache");
return null;
}
long now=DateTimeUtility.getCurrentDate();
cc.code=headers.getResponseCode();
cc.date=now;
cc.responseTime=now;
cc.requestTime=requestTime;
if(proxyRevalidate){
// Enable must-revalidate for simplicity;
// proxyRevalidate usually only applies to shared caches
cc.mustRevalidate=true;
}
if(headers.getHeaderField("date")!=null){
cc.date=headers.getHeaderFieldDate("date",Int64.MinValue);
if(cc.date==Int64.MinValue) {
noCache=true;
}
} else {
noCache=true;
}
string expiresHeader=headers.getHeaderField("expires");
if(expiresHeader!=null){
expires=headers.getHeaderFieldDate("expires",Int64.MinValue);
hasExpires=(cc.date!=Int64.MinValue);
}
if(headers.getHeaderField("age")!=null){
try {
cc.age=Int32.Parse(headers.getHeaderField("age"),NumberStyles.AllowLeadingSign,CultureInfo.InvariantCulture);
if(cc.age<0) {
cc.age=0;
}
} catch(FormatException){
cc.age=-1;
}
}
if(cc.maxAge>0 || sMaxAge>0){
long maxAge=cc.maxAge; // max age in seconds
if(maxAge==0) {
maxAge=sMaxAge;
}
if(cc.maxAge>0 && sMaxAge>0){
maxAge=Math.Max(cc.maxAge,sMaxAge);
}
cc.maxAge=maxAge*1000L; // max-age and s-maxage are in seconds
hasExpires=false;
} else if(hasExpires && !noCache){
long maxAge=expires-cc.date;
cc.maxAge=(maxAge>Int32.MaxValue) ? Int32.MaxValue : (int)maxAge;
} else if(noCache || cc.noStore){
cc.maxAge=0;
} else {
cc.maxAge=24L*3600L*1000L;
}
string reqmethod=headers.getRequestMethod();
if(reqmethod==null || (
!StringUtility.toLowerCaseAscii(reqmethod).Equals("get")))
// caching responses other than GET responses not supported
return null;
cc.requestMethod=StringUtility.toLowerCaseAscii(reqmethod);
cc.cacheability=2;
if(noCache) {
cc.cacheability=0;
} else if(privateCache) {
cc.cacheability=1;
}
int i=0;
cc.headers.Add(headers.getHeaderField(null));
while(true){
string newValue=headers.getHeaderField(i);
if(newValue==null) {
break;
}
string key=headers.getHeaderFieldKey(i);
i++;
if(key==null){
//Console.WriteLine("null key");
continue;
}
key=StringUtility.toLowerCaseAscii(key);
// to simplify matters, don't include Age header fields;
// so-called hop-by-hop headers are also not included
if(!"age".Equals(key) &&
!"connection".Equals(key) &&
!"keep-alive".Equals(key) &&
!"proxy-authenticate".Equals(key) &&
!"proxy-authorization".Equals(key) &&
!"te".Equals(key) &&
!"trailer".Equals(key) && // NOTE: NOT Trailers
!"transfer-encoding".Equals(key) &&
!"upgrade".Equals(key)){
cc.headers.Add(key);
cc.headers.Add(newValue);
}
}
//Console.WriteLine(" cc: %s",cc);
return cc;
}