Wrong http.request.url reported when host header is set

[danilobuerger]

Sometimes it is useful to connect to a url and have a different host header:

   The "Host" header field in a request provides the host and port
   information from the target URI, enabling the origin server to
   distinguish among resources while servicing requests for multiple
   host names on a single IP address.

https://tools.ietf.org/html/rfc7230#section-5.4

When this is the case, the reported http.request.url contains the host header instead of the host from the connecting url.

For example:

fetch("http://url.example/path", { headers: { host: "host.example" }})

would be reported as http://host.example/path instead of http://url.example/path.

[willarmiros]

Hi @danilobuerger,

That's a fair calllout, we do parse the host header for the name of the subsegment here, and for the http.request.url field as you said here. I would be open to a PR to prefer parsing the hostname from the URL instead.

[danilobuerger]

@willarmiros Thanks for your response. Sadly I don't have the time to submit a proper PR at this time. However, here is my patch file if somebody is willing to submit it as a PR or runs into the same issue:

diff --git a/node_modules/aws-xray-sdk-core/lib/patchers/http_p.js b/node_modules/aws-xray-sdk-core/lib/patchers/http_p.js
index 7743ecd..6ea5fc7 100644
--- a/node_modules/aws-xray-sdk-core/lib/patchers/http_p.js
+++ b/node_modules/aws-xray-sdk-core/lib/patchers/http_p.js
@@ -135,7 +135,7 @@ function enableCapture(module, downstreamXRayEnabled, subsegmentCallback) {
       } else {
         var madeItToDownstream = (e.code !== 'ECONNREFUSED');
 
-        subsegment.addRemoteRequestData(this, null, madeItToDownstream && downstreamXRayEnabled);
+        subsegment.addRemoteRequestData(this, options, null, madeItToDownstream && downstreamXRayEnabled);
         subsegment.close(e);
       }
 
@@ -164,7 +164,7 @@ function enableCapture(module, downstreamXRayEnabled, subsegmentCallback) {
         if (cause)
           subsegment[cause] = true;
 
-        subsegment.addRemoteRequestData(res.req, res, !!downstreamXRayEnabled);
+        subsegment.addRemoteRequestData(res.req, options, res, !!downstreamXRayEnabled);
         subsegment.close();
       });
 
diff --git a/node_modules/aws-xray-sdk-core/lib/segments/attributes/remote_request_data.js b/node_modules/aws-xray-sdk-core/lib/segments/attributes/remote_request_data.js
index 6986794..bdb987b 100644
--- a/node_modules/aws-xray-sdk-core/lib/segments/attributes/remote_request_data.js
+++ b/node_modules/aws-xray-sdk-core/lib/segments/attributes/remote_request_data.js
@@ -12,9 +12,9 @@ function RemoteRequestData(req, res, downstreamXRayEnabled) {
   this.init(req, res, downstreamXRayEnabled);
 }
 
-RemoteRequestData.prototype.init = function init(req, res, downstreamXRayEnabled) {
+RemoteRequestData.prototype.init = function init(req, options, res, downstreamXRayEnabled) {
   this.request = {
-    url: (req.agent && req.agent.protocol) ? (req.agent.protocol + '//' + req.getHeader('host') +  stripQueryStringFromPath(req.path)) : '',
+    url: (req.agent && req.agent.protocol) ? (req.agent.protocol + '//' + options.host +  stripQueryStringFromPath(req.path)) : '',
     method: req.method || '',
   };
 
diff --git a/node_modules/aws-xray-sdk-core/lib/segments/attributes/subsegment.js b/node_modules/aws-xray-sdk-core/lib/segments/attributes/subsegment.js
index 5e717ef..5923cfe 100644
--- a/node_modules/aws-xray-sdk-core/lib/segments/attributes/subsegment.js
+++ b/node_modules/aws-xray-sdk-core/lib/segments/attributes/subsegment.js
@@ -217,8 +217,8 @@ Subsegment.prototype.addError = function addError(err, remote) {
  * @param {boolean} downstreamXRayEnabled - when true, adds a "traced": true hint to generated subsegments such that the AWS X-Ray service expects a corresponding segment from the downstream service.
  */
 
-Subsegment.prototype.addRemoteRequestData = function addRemoteRequestData(req, res, downstreamXRayEnabled) {
-  this.http = new RemoteRequestData(req, res, downstreamXRayEnabled);
+Subsegment.prototype.addRemoteRequestData = function addRemoteRequestData(req, options, res, downstreamXRayEnabled) {
+  this.http = new RemoteRequestData(req, options, res, downstreamXRayEnabled);
   if ('traced' in this.http.request) {
     this.traced = this.http.request.traced;
     delete this.http.request.traced;

[willarmiros]

@danilobuerger thanks for adding this! We can't reorder the parameters like that to avoid a breaking change, but adding the options parameter last is an acceptable change if we do make a quick PR.