From dbcbdee8c0c98dec5d268d90a378368effddae80 Mon Sep 17 00:00:00 2001
From: Olamide <Olamide@thoughtbot.com>
Date: Fri, 5 Apr 2024 12:08:59 +0100
Subject: [PATCH] Enable header check for multiple headers

---
 aws/waf/main.tf      | 103 ++++++++++++++++++++++++++++++++++++++-----
 aws/waf/outputs.tf   |   5 +++
 aws/waf/variables.tf |  11 +++--
 3 files changed, 105 insertions(+), 14 deletions(-)

diff --git a/aws/waf/main.tf b/aws/waf/main.tf
index fcf54bcc..b22e5ea7 100644
--- a/aws/waf/main.tf
+++ b/aws/waf/main.tf
@@ -31,21 +31,104 @@ resource "aws_wafv2_web_acl" "main" {
           block {}
         }
       }
-      statement {
-        byte_match_statement {
-          field_to_match {
-            single_header {
-              name = lower(rule.value["header_name"])
+      dynamic "statement" {
+        for_each = length(rule.value["header_values"]) == 1 ? rule.value["header_values"] : {}
+        content {
+          dynamic "byte_match_statement" {
+            for_each = length(statement.value["not_statement"]) == false ? [1] : []
+            content {
+              field_to_match {
+                single_header {
+                  name = lower(statement.value["header_name"])
+                }
+              }
+
+              positional_constraint = "CONTAINS"
+
+              search_string = statement.value["header_value"]
+
+              text_transformation {
+                priority = 1
+                type     = "LOWERCASE"
+              }
+            }
+          }
+          dynamic "not_statement" {
+            for_each = length(statement.value["not_statement"]) == true ? [1] : []
+            content {
+              statement {
+                byte_match_statement {
+                  field_to_match {
+                    single_header {
+                      name = lower(statement.value["header_name"])
+                    }
+                  }
+
+                  positional_constraint = "CONTAINS"
+
+                  search_string = statement.value["header_value"]
+
+                  text_transformation {
+                    priority = 1
+                    type     = "LOWERCASE"
+                  }
+                }
+              }
             }
           }
+        }
+      }
+      dynamic "statement" {
+        for_each = length(rule.value["header_values"]) > 1 ? rule.value["header_values"] : {}
+        content {
+          and_statement {
+            dynamic "statement" {
+              for_each = rule.value["header_values"]
+              content {
+                dynamic "byte_match_statement" {
+                  for_each = length(statement.value["not_statement"]) == false ? [1] : []
+                  content {
+                    field_to_match {
+                      single_header {
+                        name = lower(statement.value["header_name"])
+                      }
+                    }
 
-          positional_constraint = "CONTAINS"
+                    positional_constraint = "CONTAINS"
 
-          search_string = rule.value["header_value"]
+                    search_string = statement.value["header_value"]
 
-          text_transformation {
-            priority = 1
-            type     = "LOWERCASE"
+                    text_transformation {
+                      priority = 1
+                      type     = "LOWERCASE"
+                    }
+                  }
+                }
+                dynamic "not_statement" {
+                  for_each = length(statement.value["not_statement"]) == true ? [1] : []
+                  content {
+                    statement {
+                      byte_match_statement {
+                        field_to_match {
+                          single_header {
+                            name = lower(statement.value["header_name"])
+                          }
+                        }
+
+                        positional_constraint = "CONTAINS"
+
+                        search_string = statement.value["header_value"]
+
+                        text_transformation {
+                          priority = 1
+                          type     = "LOWERCASE"
+                        }
+                      }
+                    }
+                  }
+                }
+              }
+            }
           }
         }
       }
diff --git a/aws/waf/outputs.tf b/aws/waf/outputs.tf
index f0a1776f..dd7a7ccb 100644
--- a/aws/waf/outputs.tf
+++ b/aws/waf/outputs.tf
@@ -2,3 +2,8 @@ output "aws_waf_arn" {
   description = "The arn for AWS WAF WebACL."
   value       = aws_wafv2_web_acl.main.arn
 }
+
+output "waf_logs_sns_topic_arn" {
+  description = "The arn for the SNS topic to receive the AWS WAF logs"
+  value       = aws_sns_topic.waf_logs_sns_subscription.arn
+}
diff --git a/aws/waf/variables.tf b/aws/waf/variables.tf
index dee871fb..69f11f71 100644
--- a/aws/waf/variables.tf
+++ b/aws/waf/variables.tf
@@ -46,10 +46,13 @@ variable "rate_limit_rules" {
 variable "header_match_rules" {
   description = "Rule statement to inspect and match the header for an incoming request."
   type = map(object({
-    name           = string               # Name of the header match rule group
-    priority       = number               # Relative processing order for header match rule relative to other rules processed by AWS WAF.
-    header_name    = string               # This is the name of the header to inspect for all incoming requests.
-    header_value   = string               # This is the value to look out for a matching header name for all incoming requests
+    name     = string                       # Name of the header match rule group
+    priority = number                       # Relative processing order for header match rule relative to other rules processed by AWS WAF.
+    header_values = map(object({            # Header values contains a map of headers to inspect. You can provide multiple headers and values, all headers will be inspected together with `AND` logic.
+      header_name   = string                # This is the name of the header to inspect for all incoming requests.
+      header_value  = string                # This is the value to look out for a matching header name for all incoming requests
+      not_statement = optional(bool, false) # This indicates if the result this header match should be negated. The negated result will be joined with other header match results using `AND` logic if more than 1 header is provided.
+    }))
     count_override = optional(bool, true) # If true, this will override the rule action setting to `count`, if false, the rule action will be set to `block`. Default value is false.
   }))