From 9616c55e2f700553dd18b1649789062b5f0226a1 Mon Sep 17 00:00:00 2001
From: ajukes <ajukes@vibecoms.co.uk>
Date: Tue, 11 Apr 2023 17:26:10 +0100
Subject: [PATCH] custom propagator to set span context traceId to a hex
 version of callSid

---
 lib/utils/call-tracer.js    | 58 +++++++++++++++++++------------------
 lib/utils/sip-propagator.js | 50 ++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+), 28 deletions(-)
 create mode 100644 lib/utils/sip-propagator.js

diff --git a/lib/utils/call-tracer.js b/lib/utils/call-tracer.js
index b6b229e83..bebb06914 100644
--- a/lib/utils/call-tracer.js
+++ b/lib/utils/call-tracer.js
@@ -1,39 +1,42 @@
-const {context, trace} = require('@opentelemetry/api');
+
+const {trace, context, SpanKind} = require('@opentelemetry/api');
 const {Dialog} = require('drachtio-srf');
+const {SipPropagator} = require('./sip-propagator');
+
 class RootSpan {
   constructor(callType, req) {
-    let tracer, callSid, linkedSpanId;
+    const tracer = req.srf.locals.otel.tracer;
+    const propagator = new SipPropagator();
+    const ctx = propagator.extract(context.active(), req);
+    this._span = tracer.startSpan(callType || 'incoming-call', {
+      kind: SpanKind.CONSUMER,
+      attributes: this.getSpanAttributes(req),
+      root: false
+    }, ctx);
+    this._ctx = trace.setSpan(ctx, this._span);
+    this.tracer = tracer;
+  }
 
+  getSpanAttributes(req) {
     if (req instanceof Dialog) {
-      const dlg = req;
-      tracer = dlg.srf.locals.otel.tracer;
-      callSid = dlg.callSid;
-      linkedSpanId = dlg.linkedSpanId;
-    }
-    else {
-      tracer = req.srf.locals.otel.tracer;
-      callSid = req.locals.callSid;
-    }
-    this._span = tracer.startSpan(callType || 'incoming-call');
-    if (req instanceof Dialog) {
-      const dlg = req;
-      this._span.setAttributes({
+      const {sip, callSid, linkedSpanId} = req;
+      const {callId} = sip;
+      return {
         linkedSpanId,
-        callId: dlg.sip.callId
-      });
-    }
-    else {
-      this._span.setAttributes({
+        callId,
+        callSid
+      };
+    } else {
+      const {locals} = req;
+      const {callSid} = locals;
+      return {
         callSid,
         accountSid: req.get('X-Account-Sid'),
-        applicationSid: req.locals.application_sid,
+        applicationSid: locals.application_sid,
         callId: req.get('Call-ID'),
         externalCallId: req.get('X-CID')
-      });
+      };
     }
-
-    this._ctx = trace.setSpan(context.active(), this._span);
-    this.tracer = tracer;
   }
 
   get context() {
@@ -54,7 +57,7 @@ class RootSpan {
 
   getTracingPropagation(encoding) {
     // TODO: support encodings beyond b3 https://github.com/openzipkin/b3-propagation
-    if (this._span  && this.traceId !== '00000000000000000000000000000000') {
+    if (this._span && this.traceId !== '00000000000000000000000000000000') {
       return `${this.traceId}-${this.spanId}-1`;
     }
   }
@@ -69,10 +72,9 @@ class RootSpan {
 
   startChildSpan(name, attributes) {
     const span = this.tracer.startSpan(name, attributes, this._ctx);
-    const ctx = trace.setSpan(context.active(), span);
+    const ctx = trace.setSpan(this._ctx, span);
     return {span, ctx};
   }
 }
 
 module.exports = RootSpan;
-
diff --git a/lib/utils/sip-propagator.js b/lib/utils/sip-propagator.js
new file mode 100644
index 000000000..c51a44219
--- /dev/null
+++ b/lib/utils/sip-propagator.js
@@ -0,0 +1,50 @@
+const {TraceFlags, trace, isSpanContextValid, isValidTraceId, isValidSpanId} = require('@opentelemetry/api');
+const {isTracingSuppressed} = require('@opentelemetry/core');
+const {Dialog} = require('drachtio-srf');
+
+class SipPropagator {
+  constructor() {
+  }
+
+  inject(context, carrier, setter) {
+    const spanContext = trace.getSpanContext(context);
+    if (!spanContext || !isSpanContextValid(spanContext) || isTracingSuppressed(context)) {
+      return;
+    }
+    setter.set(carrier, 'traceId', spanContext.traceId);
+    setter.set(carrier, 'spanId', spanContext.spanId);
+  }
+
+  extract(context, carrier) {
+    const callSid = this.getCallSidFromCarrier(carrier);
+    const traceId = this.getHexValue(callSid);
+    const spanId = traceId.substring(0, 16);
+    if (!isValidTraceId(traceId) || !isValidSpanId(spanId)) {
+      return context;
+    }
+    return trace.setSpanContext(context, {
+      traceId,
+      spanId,
+      isRemote: true,
+      traceFlags: TraceFlags.SAMPLED
+    });
+  }
+
+  fields() {
+    return ['traceId', 'spanId'];
+  }
+
+  getCallSidFromCarrier(carrier) {
+    if (carrier instanceof Dialog) {
+      return carrier.callSid;
+    } else {
+      return carrier.locals.callSid;
+    }
+  }
+
+  getHexValue(callSid) {
+    return callSid.replaceAll('-', '');
+  }
+}
+
+exports.SipPropagator = SipPropagator;