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Copy original HTTP request headers #433

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merged 3 commits into from
Aug 21, 2017
Merged

Copy original HTTP request headers #433

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7183bd1
merged changes from @jwoyame #186 into master
gavinr Aug 14, 2017
bf0ec29
make sure certain headers are not sent #362
gavinr Aug 14, 2017
29da88d
removed commented code and fixed variable issue
gavinr Aug 18, 2017
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123 changes: 99 additions & 24 deletions DotNet/proxy.ashx
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Original file line number Diff line number Diff line change
Expand Up @@ -279,15 +279,15 @@ public class proxy : IHttpHandler {
//forwarding original request
System.Net.WebResponse serverResponse = null;
try {
serverResponse = forwardToServer(context, addTokenToUri(requestUri, token, tokenParamName), postBody, credentials);
serverResponse = forwardToServer(context.Request, addTokenToUri(requestUri, token, tokenParamName), postBody, credentials);
} catch (System.Net.WebException webExc) {

string errorMsg = webExc.Message + " " + uri;
log(TraceLevel.Error, errorMsg);

if (webExc.Response != null)
{
copyHeaders(webExc.Response as System.Net.HttpWebResponse, context.Response);
copyResponseHeaders(webExc.Response as System.Net.HttpWebResponse, context.Response);

using (Stream responseStream = webExc.Response.GetResponseStream())
{
Expand Down Expand Up @@ -328,7 +328,7 @@ public class proxy : IHttpHandler {
//server returned error - potential cause: token has expired.
//we'll do second attempt to call the server with renewed token:
token = getNewTokenIfCredentialsAreSpecified(serverUrl, requestUri);
serverResponse = forwardToServer(context, addTokenToUri(requestUri, token, tokenParamName), postBody);
serverResponse = forwardToServer(context.Request, addTokenToUri(requestUri, token, tokenParamName), postBody);

//storing the token in Application scope, to do not waste time on requesting new one untill it expires or the app is restarted.
context.Application.Lock();
Expand Down Expand Up @@ -367,20 +367,33 @@ public class proxy : IHttpHandler {
return new byte[0];
}

private System.Net.WebResponse forwardToServer(HttpContext context, string uri, byte[] postBody, System.Net.NetworkCredential credentials = null)
private void writeRequestPostBody(System.Net.HttpWebRequest req, byte[] bytes)
{
return
postBody.Length > 0?
doHTTPRequest(uri, postBody, "POST", context.Request.Headers["referer"], context.Request.ContentType, credentials):
doHTTPRequest(uri, context.Request.HttpMethod, credentials);
if (bytes != null && bytes.Length > 0)
{
req.ContentLength = bytes.Length;
using (Stream outputStream = req.GetRequestStream())
{
outputStream.Write(bytes, 0, bytes.Length);
}
}
}

private System.Net.WebResponse forwardToServer(HttpRequest req, string uri, byte[] postBody, System.Net.NetworkCredential credentials = null)
{
string method = postBody.Length > 0 ? "POST" : req.HttpMethod;
System.Net.HttpWebRequest forwardReq = createHTTPRequest(uri, method, req.ContentType, credentials);
copyRequestHeaders(req, forwardReq);
writeRequestPostBody(forwardReq, postBody);
return forwardReq.GetResponse();
}

/// <summary>
/// Attempts to copy all headers from the fromResponse to the the toResponse.
/// </summary>
/// <param name="fromResponse">The response that we are copying the headers from</param>
/// <param name="toResponse">The response that we are copying the headers to</param>
private void copyHeaders(System.Net.WebResponse fromResponse, HttpResponse toResponse)
private void copyResponseHeaders(System.Net.WebResponse fromResponse, HttpResponse toResponse)
{
foreach (var headerKey in fromResponse.Headers.AllKeys)
{
Expand Down Expand Up @@ -410,6 +423,73 @@ public class proxy : IHttpHandler {
}
}

private void copyRequestHeaders(HttpRequest fromRequest, System.Net.HttpWebRequest toRequest)
{
foreach (var headerKey in fromRequest.Headers.AllKeys)
{
string headerValue = fromRequest.Headers[headerKey];
string headerKeyLower = headerKey.ToLower();

switch (headerKeyLower)
{
case "accept-encoding":
case "proxy-connection":
continue;
case "range":
setRangeHeader(toRequest, headerValue);
break;
case "accept":
toRequest.Accept = headerValue;
break;
case "if-modified-since":
DateTime modDT;
if (DateTime.TryParse(headerValue, out modDT))
toRequest.IfModifiedSince = modDT;
break;
case "referer":
toRequest.Referer = headerValue;
break;
case "user-agent":
toRequest.UserAgent = headerValue;
break;
default:
// Some headers are restricted and would throw an exception:
// http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.headers(v=vs.100).aspx
// Also check for our custom list of headers that should not be sent (https://github.com/Esri/resource-proxy/issues/362)
if (!System.Net.WebHeaderCollection.IsRestricted(headerKey) &&
headerKeyLower != "accept-encoding" &&
headerKeyLower != "proxy-connection" &&
headerKeyLower != "connection" &&
headerKeyLower != "keep-alive" &&
headerKeyLower != "proxy-authenticate" &&
headerKeyLower != "proxy-authorization" &&
headerKeyLower != "transfer-encoding" &&
headerKeyLower != "te" &&
headerKeyLower != "trailer" &&
headerKeyLower != "upgrade" &&
toRequest.Headers[headerKey] == null)
toRequest.Headers[headerKey] = headerValue;
break;
}
}
}

private void setRangeHeader(System.Net.HttpWebRequest req, string range)
{
string[] specifierAndRange = range.Split('=');
if (specifierAndRange.Length == 2)
{
string specifier = specifierAndRange[0];
string[] fromAndTo = specifierAndRange[1].Split('-');
if (fromAndTo.Length == 2)
{
int from, to;
if (int.TryParse(fromAndTo[0], out from) && int.TryParse(fromAndTo[1], out to))
req.AddRange(specifier, from, to);
}
}
}

private bool fetchAndPassBackToClient(System.Net.WebResponse serverResponse, HttpResponse clientResponse, bool ignoreAuthenticationErrors) {
if (serverResponse != null) {
using (Stream byteStream = serverResponse.GetResponseStream()) {
Expand All @@ -427,14 +507,14 @@ public class proxy : IHttpHandler {
return true;

//Copy the header info and the content to the reponse to client
copyHeaders(serverResponse, clientResponse);
copyResponseHeaders(serverResponse, clientResponse);
clientResponse.Write(strResponse);
}
} else {
// Binary response (image, lyr file, other binary file)

//Copy the header info to the reponse to client
copyHeaders(serverResponse, clientResponse);
copyResponseHeaders(serverResponse, clientResponse);
// Tell client not to cache the image since it's dynamic
clientResponse.CacheControl = "no-cache";
byte[] buffer = new byte[32768];
Expand Down Expand Up @@ -470,33 +550,28 @@ public class proxy : IHttpHandler {
}
}

return doHTTPRequest(uri, bytes, method, PROXY_REFERER, contentType, credentials);
System.Net.HttpWebRequest req = createHTTPRequest(uri, method, contentType, credentials);
req.Referer = PROXY_REFERER;
writeRequestPostBody(req, bytes);
return req.GetResponse();
}

private System.Net.WebResponse doHTTPRequest(string uri, byte[] bytes, string method, string referer, string contentType, System.Net.NetworkCredential credentials = null)
private System.Net.HttpWebRequest createHTTPRequest(string uri, string method, string contentType, System.Net.NetworkCredential credentials = null)
{
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
System.Net.HttpWebRequest req = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(uri);
req.ServicePoint.Expect100Continue = false;
req.Referer = referer;
req.Method = method;
if (method == "POST")
req.ContentType = string.IsNullOrEmpty(contentType) ? "application/x-www-form-urlencoded" : contentType;

// Use the default system proxy
req.Proxy = SYSTEM_PROXY;

if (credentials != null)
req.Credentials = credentials;

if (bytes != null && bytes.Length > 0 || method == "POST") {
req.Method = "POST";
req.ContentType = string.IsNullOrEmpty(contentType) ? "application/x-www-form-urlencoded" : contentType;
if (bytes != null && bytes.Length > 0)
req.ContentLength = bytes.Length;
using (Stream outputStream = req.GetRequestStream()) {
outputStream.Write(bytes, 0, bytes.Length);
}
}
return req.GetResponse();
return req;
}

private string webResponseToString(System.Net.WebResponse serverResponse) {
Expand Down