From 0ed93de841f81b3a00c06ef20e91fd70751054b0 Mon Sep 17 00:00:00 2001
From: MuckT <mcgtom10@gmail.com>
Date: Thu, 2 Dec 2021 23:33:05 -0800
Subject: [PATCH 1/5] fix: handle duplicate headers

---
 lib/common.js | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/lib/common.js b/lib/common.js
index 373de6e99..bc26ec200 100644
--- a/lib/common.js
+++ b/lib/common.js
@@ -192,7 +192,7 @@ function isJSONContent(headers) {
 /**
  * Return a new object with all field names of the headers lower-cased.
  *
- * Duplicates throw an error.
+ * Duplicates take the last value provided.
  */
 function headersFieldNamesToLowerCase(headers) {
   if (!isPlainObject(headers)) {
@@ -202,12 +202,12 @@ function headersFieldNamesToLowerCase(headers) {
   const lowerCaseHeaders = {}
   Object.entries(headers).forEach(([fieldName, fieldValue]) => {
     const key = fieldName.toLowerCase()
-    if (lowerCaseHeaders[key] !== undefined) {
-      throw Error(
-        `Failed to convert header keys to lower case due to field name conflict: ${key}`
-      )
+    const regex = new RegExp(fieldValue, 'i');
+    if(fieldValue instanceof RegExp && lowerCaseHeaders[key] === undefined) {
+      lowerCaseHeaders[key] = fieldValue
+    } else if (!regex.test(lowerCaseHeaders[key])) {
+      lowerCaseHeaders[key] = fieldValue
     }
-    lowerCaseHeaders[key] = fieldValue
   })
 
   return lowerCaseHeaders

From c7ce87920e8ab589bfb678de731bf2882bf50eec Mon Sep 17 00:00:00 2001
From: MuckT <mcgtom10@gmail.com>
Date: Thu, 2 Dec 2021 23:33:34 -0800
Subject: [PATCH 2/5] test: update test for duplicate headers

---
 tests/test_common.js | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/tests/test_common.js b/tests/test_common.js
index d51edb499..ddfa888af 100644
--- a/tests/test_common.js
+++ b/tests/test_common.js
@@ -165,15 +165,17 @@ describe('`headersFieldNamesToLowerCase()`', () => {
     expect(input).to.deep.equal(inputClone) // assert the input is not mutated
   })
 
-  it('throws on conflicting keys', () => {
-    expect(() =>
-      common.headersFieldNamesToLowerCase({
-        HoSt: 'example.test',
-        HOST: 'example.test',
-      })
-    ).to.throw(
-      'Failed to convert header keys to lower case due to field name conflict: host'
-    )
+  it('handles duplicates of conflicting keys using last value provided', () => {
+    const results = common.headersFieldNamesToLowerCase({
+      hOsT: 'example.test',
+      HoSt: 'example.test',
+      HOST: 'final.example.test',
+    })
+    const expected = {
+      host: 'final.example.test',
+    }
+
+    expect(results).to.deep.equal(expected)
   })
 })
 

From c4e50620966de17438d043c60a6b56b50c44cfb5 Mon Sep 17 00:00:00 2001
From: MuckT <mcgtom10@gmail.com>
Date: Thu, 2 Dec 2021 23:48:43 -0800
Subject: [PATCH 3/5] fix: adjust regex to avoid partial match

---
 lib/common.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/common.js b/lib/common.js
index bc26ec200..f877fcb3c 100644
--- a/lib/common.js
+++ b/lib/common.js
@@ -202,7 +202,7 @@ function headersFieldNamesToLowerCase(headers) {
   const lowerCaseHeaders = {}
   Object.entries(headers).forEach(([fieldName, fieldValue]) => {
     const key = fieldName.toLowerCase()
-    const regex = new RegExp(fieldValue, 'i');
+    const regex = new RegExp(`^{fieldValue}$`, 'i');
     if(fieldValue instanceof RegExp && lowerCaseHeaders[key] === undefined) {
       lowerCaseHeaders[key] = fieldValue
     } else if (!regex.test(lowerCaseHeaders[key])) {

From 0534b0e535141086f46ef540be2b246faf3168ad Mon Sep 17 00:00:00 2001
From: MuckT <mcgtom10@gmail.com>
Date: Thu, 2 Dec 2021 23:49:04 -0800
Subject: [PATCH 4/5] test: adjust test for partial regex match

---
 tests/test_common.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tests/test_common.js b/tests/test_common.js
index ddfa888af..aeb64d1e5 100644
--- a/tests/test_common.js
+++ b/tests/test_common.js
@@ -170,9 +170,11 @@ describe('`headersFieldNamesToLowerCase()`', () => {
       hOsT: 'example.test',
       HoSt: 'example.test',
       HOST: 'final.example.test',
+      hosts: 'final.example.test'
     })
     const expected = {
       host: 'final.example.test',
+      hosts: 'final.example.test'
     }
 
     expect(results).to.deep.equal(expected)

From 4a5a537735d53919cbb630589d6ebf180951a57c Mon Sep 17 00:00:00 2001
From: MuckT <mcgtom10@gmail.com>
Date: Fri, 3 Dec 2021 08:21:07 -0800
Subject: [PATCH 5/5] fix: use field value in template literal

---
 lib/common.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/common.js b/lib/common.js
index f877fcb3c..e4623dc91 100644
--- a/lib/common.js
+++ b/lib/common.js
@@ -202,7 +202,7 @@ function headersFieldNamesToLowerCase(headers) {
   const lowerCaseHeaders = {}
   Object.entries(headers).forEach(([fieldName, fieldValue]) => {
     const key = fieldName.toLowerCase()
-    const regex = new RegExp(`^{fieldValue}$`, 'i');
+    const regex = new RegExp(`^${fieldValue}$`, 'i');
     if(fieldValue instanceof RegExp && lowerCaseHeaders[key] === undefined) {
       lowerCaseHeaders[key] = fieldValue
     } else if (!regex.test(lowerCaseHeaders[key])) {