From 7ba7e569294595fac84c420a6cfd80941d7cb180 Mon Sep 17 00:00:00 2001
From: Simone Basso <bassosimone@gmail.com>
Date: Thu, 9 Jul 2020 12:51:40 +0200
Subject: [PATCH] fix(net/archival): emit sorted headers

See failing test https://github.com/ooni/probe-engine/pull/751/checks?check_run_id=853562310

Spotted as part of https://github.com/ooni/probe-engine/issues/740
---
 netx/archival/archival.go      |  4 ++++
 netx/archival/archival_test.go | 14 ++++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/netx/archival/archival.go b/netx/archival/archival.go
index b5dc251b..844c4274 100644
--- a/netx/archival/archival.go
+++ b/netx/archival/archival.go
@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"sort"
 	"strconv"
 	"strings"
 	"time"
@@ -304,6 +305,9 @@ func addheaders(
 			})
 		}
 	}
+	sort.Slice(*destList, func(i, j int) bool {
+		return (*destList)[i].Key < (*destList)[j].Key
+	})
 }
 
 // NewRequestList returns the list for "requests"
diff --git a/netx/archival/archival_test.go b/netx/archival/archival_test.go
index 99f730e8..cd975e6c 100644
--- a/netx/archival/archival_test.go
+++ b/netx/archival/archival_test.go
@@ -201,7 +201,9 @@ func TestNewRequestList(t *testing.T) {
 			T: 0.01,
 		}},
 	}, {
-		name: "run with redirect",
+		// for an example of why we need to sort headers, see
+		// https://github.com/ooni/probe-engine/pull/751/checks?check_run_id=853562310
+		name: "run with redirect and headers to sort",
 		args: args{
 			begin: begin,
 			events: []trace.Event{{
@@ -242,11 +244,6 @@ func TestNewRequestList(t *testing.T) {
 			Response: archival.HTTPResponse{
 				Code: 302,
 				HeadersList: []archival.HTTPHeader{{
-					Key: "Server",
-					Value: archival.MaybeBinaryValue{
-						Value: "orchestra/0.1.0-dev",
-					},
-				}, {
 					Key: "Location",
 					Value: archival.MaybeBinaryValue{
 						Value: "https://x.example.com",
@@ -256,6 +253,11 @@ func TestNewRequestList(t *testing.T) {
 					Value: archival.MaybeBinaryValue{
 						Value: "https://y.example.com",
 					},
+				}, {
+					Key: "Server",
+					Value: archival.MaybeBinaryValue{
+						Value: "orchestra/0.1.0-dev",
+					},
 				}},
 				Headers: map[string]archival.MaybeBinaryValue{
 					"Server":   {Value: "orchestra/0.1.0-dev"},