From a711208a7588f56cb6e366e76b4e7a10af3782e0 Mon Sep 17 00:00:00 2001
From: Benjamin Valentin <benjamin.valentin@ml-pa.com>
Date: Mon, 20 Sep 2021 23:03:23 +0200
Subject: [PATCH] tools/zep_dispatch: add support for foren6 sniffer

---
 dist/tools/zep_dispatch/main.c     |  7 ++++++-
 dist/tools/zep_dispatch/topology.c | 20 ++++++++++++++++++++
 dist/tools/zep_dispatch/topology.h | 15 ++++++++++++++-
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/dist/tools/zep_dispatch/main.c b/dist/tools/zep_dispatch/main.c
index b889f36951..e13a701fa0 100644
--- a/dist/tools/zep_dispatch/main.c
+++ b/dist/tools/zep_dispatch/main.c
@@ -79,7 +79,12 @@ static void _send_topology(void *ctx, void *buffer, size_t len,
     uint8_t mac_src_len;
 
     if (zep_parse_mac(buffer, len, mac_src, &mac_src_len)) {
-        topology_add(ctx, mac_src, mac_src_len, src_addr);
+        /* a sniffer node has no MAC address and will receive every packet */
+        if (mac_src_len == 0) {
+            topology_set_sniffer(ctx, src_addr);
+        } else {
+            topology_add(ctx, mac_src, mac_src_len, src_addr);
+        }
     }
     topology_send(ctx, sock, src_addr, buffer, len);
 }
diff --git a/dist/tools/zep_dispatch/topology.c b/dist/tools/zep_dispatch/topology.c
index 1eabfb6907..1cef2f322d 100644
--- a/dist/tools/zep_dispatch/topology.c
+++ b/dist/tools/zep_dispatch/topology.c
@@ -201,6 +201,11 @@ void topology_send(const topology_t *t, int sock,
                    const struct sockaddr_in6 *src_addr,
                    void *buffer, size_t len)
 {
+    if (t->has_sniffer) {
+        sendto(sock, buffer, len, 0,
+               (struct sockaddr *)&t->sniffer_addr, sizeof(t->sniffer_addr));
+    }
+
     for (list_node_t *edge = t->edges.next; edge; edge = edge->next) {
         struct edge *super = container_of(edge, struct edge, next);
 
@@ -277,3 +282,18 @@ bool topology_add(topology_t *t, const uint8_t *mac, uint8_t mac_len,
 
     return true;
 }
+
+void topology_set_sniffer(topology_t *t, struct sockaddr_in6 *addr)
+{
+    if (t->has_sniffer) {
+        return;
+    }
+
+    char addr_str[INET6_ADDRSTRLEN];
+    getnameinfo((struct sockaddr*)addr, sizeof(*addr),
+                addr_str, sizeof(addr_str), 0, 0, NI_NUMERICHOST);
+    printf("adding sniffer %s\n", addr_str);
+
+    memcpy(&t->sniffer_addr, addr, sizeof(t->sniffer_addr));
+    t->has_sniffer = true;
+}
diff --git a/dist/tools/zep_dispatch/topology.h b/dist/tools/zep_dispatch/topology.h
index 03499034b8..9b3d61d989 100644
--- a/dist/tools/zep_dispatch/topology.h
+++ b/dist/tools/zep_dispatch/topology.h
@@ -9,6 +9,7 @@
 #define TOPOLOGY_H
 
 #include "list.h"
+#include <netinet/in.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -18,9 +19,11 @@ extern "C" {
  * @brief   Struct describing a graph of nodes and their connections
  */
 typedef struct {
-    bool flat;          /**< flat topology, all nodes are connected to each other */
     list_node_t nodes;  /**< list of nodes */
     list_node_t edges;  /**< list of connections between nodes. Unused if topology is flat */
+    struct sockaddr_in6 sniffer_addr;   /**< address of sniffer node. Unused if topology is flat */
+    bool has_sniffer;   /**< true if a sniffer node is connected. Unused if topology is flat */
+    bool flat;          /**< flat topology, all nodes are connected to each other */
 } topology_t;
 
 /**
@@ -58,6 +61,16 @@ int topology_print(const char *file_out, const topology_t *t);
 bool topology_add(topology_t *t, const uint8_t *mac, uint8_t mac_len,
                   struct sockaddr_in6 *addr);
 
+/**
+ * @brief   Add a sniffer to the topology
+ *          A sniffer node will receive every packet but won't be able to
+ *          send packets on it's own.
+ *
+ * @param[in, out]  t       topology to configure
+ * @param[in]       addr    real address of the sniffer
+ */
+void topology_set_sniffer(topology_t *t, struct sockaddr_in6 *addr);
+
 /**
  * @brief   Send a buffer to all nodes connected to a source node
  *