From 65c9d4f30b232dfd0273c35109bfed812b27fb13 Mon Sep 17 00:00:00 2001
From: Christian Giese <christian@rtbrick.com>
Date: Thu, 14 Apr 2022 09:41:32 +0200
Subject: [PATCH] #71 mac-modifier

Add new configuration option to modify third byte of
the access session MAC address.
---
 code/bngblaster/src/bbl_config.c            | 8 ++++++++
 code/bngblaster/src/bbl_ctx.h               | 1 +
 code/bngblaster/src/bbl_session.c           | 2 +-
 docsrc/sources/configuration/interfaces.rst | 5 ++++-
 4 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/code/bngblaster/src/bbl_config.c b/code/bngblaster/src/bbl_config.c
index a675ee5f..895efd81 100644
--- a/code/bngblaster/src/bbl_config.c
+++ b/code/bngblaster/src/bbl_config.c
@@ -1801,6 +1801,14 @@ json_parse_config(json_t *root, bbl_ctx_s *ctx) {
         if (json_is_boolean(value)) {
             ctx->pcap.include_streams = json_boolean_value(value);
         }
+        value = json_object_get(section, "mac-modifier");
+        if (json_is_number(value)) {
+            if(json_number_value(value) < 0 || json_number_value(value) > UINT8_MAX) {
+                fprintf(stderr, "Config error: Invalid value for interfaces->mac-modifier\n");
+                return false;
+            }
+            ctx->config.mac_modifier = json_number_value(value);
+        }
 
         /* Network Interface Configuration Section */
         sub = json_object_get(section, "network");
diff --git a/code/bngblaster/src/bbl_ctx.h b/code/bngblaster/src/bbl_ctx.h
index 9654346e..a44a151a 100644
--- a/code/bngblaster/src/bbl_ctx.h
+++ b/code/bngblaster/src/bbl_ctx.h
@@ -144,6 +144,7 @@ typedef struct bbl_ctx_
     /* Config options */
     struct {
         bool interface_lock_force;
+        uint8_t mac_modifier;
 
         uint64_t tx_interval; /* TX interval in nsec */
         uint64_t rx_interval; /* RX interval in nsec */
diff --git a/code/bngblaster/src/bbl_session.c b/code/bngblaster/src/bbl_session.c
index 2c7a74f0..f6d48b4a 100644
--- a/code/bngblaster/src/bbl_session.c
+++ b/code/bngblaster/src/bbl_session.c
@@ -560,7 +560,7 @@ bbl_sessions_init(bbl_ctx_s *ctx)
         /* Set client OUI to locally administered */
         session->client_mac[0] = 0x02;
         session->client_mac[1] = 0x00;
-        session->client_mac[2] = 0x00;
+        session->client_mac[2] = ctx->config.mac_modifier;
         /* Use session identifier for remaining bytes */
         session->client_mac[3] = i>>16;
         session->client_mac[4] = i>>8;
diff --git a/docsrc/sources/configuration/interfaces.rst b/docsrc/sources/configuration/interfaces.rst
index a097529c..1c61748a 100644
--- a/docsrc/sources/configuration/interfaces.rst
+++ b/docsrc/sources/configuration/interfaces.rst
@@ -30,4 +30,7 @@
      - 32
    * - `capture-include-streams`
      - Include traffic streams in capture
-     - true
\ No newline at end of file
+     - true
+   * - `mac-modifier`
+     - Third byte of access session MAC address (0-255)
+     - 0
\ No newline at end of file