GCDWebServer Cors proxy

app.swift

import GCDWebServer

let webserver = GCDWebServer()
let proxy = CorsProxy(webserver: webserver!, urlPrefix: "/CORS/")
webserver.startWithPort(8080, bonjourName: nil)

// $ curl -i -H "Origin: test-site" http://127.0.0.1/CORS/http://my/test/site
// HTTP/1.1 200 OK
// Access-Control-Allow-Origin: test-site
// Server: GCDWebServer
// Access-Control-Allow-Credentials: true
// Connection: Close
// Access-Control-Allow-Methods: PUT,POST,GET,PATCH,DELETE
// Cache-Control: no-cache

CorsProxy.swift

import GCDWebServer

class CorsProxy {
    init(webserver : GCDWebServer!, urlPrefix: String) {
        var prefix =
            (urlPrefix.hasPrefix("/") ? "" : "/")
            + urlPrefix
            + (urlPrefix.hasSuffix("/") ? "" : "/")
        
        let pattern = "^" + NSRegularExpression.escapedPatternForString(prefix) + ".*"
        
        webserver.addHandlerForMethod("POST", pathRegex: pattern, requestClass: GCDWebServerDataRequest.self, processBlock:{ req in
            return self.sendProxyResult(prefix, req: req)
        })
        
        webserver.addHandlerForMethod("PUT", pathRegex: pattern, requestClass: GCDWebServerDataRequest.self, processBlock:{ req in
            return self.sendProxyResult(prefix, req: req)
        })
        
        webserver.addHandlerForMethod("PATCH", pathRegex: pattern, requestClass: GCDWebServerDataRequest.self, processBlock:{ req in
            return self.sendProxyResult(prefix, req: req)
        })
        
        webserver.addHandlerForMethod("DELETE", pathRegex: pattern, requestClass: GCDWebServerDataRequest.self, processBlock:{ req in
            return self.sendProxyResult(prefix, req: req)
        })
        
        webserver.addHandlerForMethod("GET", pathRegex: pattern, requestClass: GCDWebServerRequest.self, processBlock:{ req in
            return self.sendProxyResult(prefix, req: req)
        })
        
        webserver.addHandlerForMethod("OPTIONS", pathRegex: pattern, requestClass: GCDWebServerRequest.self, processBlock:{ req in
            return self.sendCorsHeaders(prefix, req: req)
        })
    }
    
    func sendProxyResult(prefix: String, req: GCDWebServerRequest) -> GCDWebServerResponse! {
        let query = req.URL.query == nil ? "" : "?" + req.URL.query!
        var url = NSURL(string: req.path.substringFromIndex(prefix.endIndex) + query)
        if (url == nil) { return sendError("Invalid URL") }
        
        var err: NSErrorPointer = nil
        var urlResp: NSURLResponse?
        let urlReq = NSMutableURLRequest(URL: url!, cachePolicy: NSURLRequestCachePolicy.ReloadIgnoringLocalCacheData, timeoutInterval: 320000)
        urlReq.HTTPMethod = req.method
        urlReq.allHTTPHeaderFields = req.headers
        urlReq.allHTTPHeaderFields?["Host"] = url!.host
        
        if (req.hasBody()) {
            urlReq.HTTPBody = (req as! GCDWebServerDataRequest).data
        }
        
        let output = NSURLConnection.sendSynchronousRequest(urlReq
            , returningResponse: &urlResp
            , error: err)
        
        if (urlResp == nil) {
            return sendError(output == nil ? nil : NSString(data: output!, encoding: NSUTF8StringEncoding) as? String);
        }
        
        var httpResponse = urlResp as! NSHTTPURLResponse
        let resp = GCDWebServerDataResponse(data: output == nil ? NSData() : output, contentType: "application/x-unknown")
        resp.statusCode = httpResponse.statusCode
        for key in httpResponse.allHeaderFields {
            if (toString(key.0) == "Content-Encoding") { continue; }
            resp.setValue(toString(key.1), forAdditionalHeader: toString(key.0))
        }
        if (output != nil) {
            resp.setValue(String(output!.length), forAdditionalHeader: "Content-Length")
        }
        return resp
    }
    
    func sendCorsHeaders(prefix: String, req: GCDWebServerRequest) -> GCDWebServerResponse! {
        let resp = GCDWebServerResponse()
        resp.setValue(toString(req.headers["Origin"]), forAdditionalHeader: "Access-Control-Allow-Origin")
        resp.setValue("PUT,POST,GET,PATCH,DELETE", forAdditionalHeader: "Access-Control-Allow-Methods")
        resp.setValue("true", forAdditionalHeader: "Access-Control-Allow-Credentials")
        return resp
    }
    
    func sendError(error: String?) -> GCDWebServerResponse! {
        var msg = error == nil ? "An error occured" : error!
        let errorData = msg.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)
        let resp = GCDWebServerDataResponse(data: errorData, contentType: "text/plain")
        resp.statusCode = 500
        return resp
    }
    
    func toString(v: AnyObject?) -> String! {
        if (v == nil) { return ""; }
        return String(stringInterpolationSegment: v!)
    }
}