* setting up framework for Regions, TransportKeys, etc

src/helpers/RegionMap.cpp

@@ -0,0 +1,35 @@
+#include "RegionMap.h"
+#include <SHA256.h>
+
+void RegionMap::load(FILESYSTEM* _fs) {
+  // TODO
+}
+void RegionMap::save(FILESYSTEM* _fs) {
+  // TODO
+}
+
+RegionEntry* RegionMap::findMatch(mesh::Packet* packet, uint8_t mask) {
+  for (int i = 0; i < num_regions; i++) {
+    auto region = &regions[i];
+    if (region->flags & mask) {   // does region allow this? (per 'mask' param)
+      TransportKey keys[4];
+      int num = _store->loadKeysFor(region->name, region->id, keys, 4);
+      for (int j = 0; j < num; j++) {
+        uint16_t code = keys[j].calcTransportCode(packet);
+        if (packet->transport_codes[0] == code) {   // a match!!
+          return region;
+        }
+      }
+    }
+  }
+  return NULL;  // no matches
+}
+
+const RegionEntry* RegionMap::findName(const char* name) const {
+  for (int i = 0; i < num_regions; i++) {
+    auto region = &regions[i];
+    if (strcmp(name, region->name) == 0) return region;
+  }
+  return NULL;  // not found
+}
+

src/helpers/RegionMap.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <Arduino.h>   // needed for PlatformIO
+#include <Packet.h>
+#include "TransportKeyStore.h"
+
+#ifndef MAX_REGION_ENTRIES
+  #define MAX_REGION_ENTRIES  32
+#endif
+
+#define REGION_ALLOW_FLOOD  0x01
+
+struct RegionEntry {
+  uint16_t id;
+  uint16_t parent;
+  uint8_t flags;
+  char name[31];
+};
+
+class RegionMap {
+  TransportKeyStore* _store;
+  uint16_t next_id;
+  uint16_t num_regions;
+  RegionEntry regions[MAX_REGION_ENTRIES];
+  RegionEntry wildcard;
+
+public:
+  RegionMap(TransportKeyStore& store) : _store(&store) {
+    next_id = 1; num_regions = 0;
+    wildcard.id = wildcard.parent = 0;
+    wildcard.flags = REGION_ALLOW_FLOOD;  // default behaviour, allow flood
+  }
+  void load(FILESYSTEM* _fs);
+  void save(FILESYSTEM* _fs);
+
+  RegionEntry* findMatch(mesh::Packet* packet, uint8_t mask);
+  const RegionEntry& getWildcard() const { return wildcard; }
+  const RegionEntry* findName(const char* name) const;
+};

src/helpers/TransportKeyStore.cpp

@@ -0,0 +1,44 @@
+#include "TransportKeyStore.h"
+#include <SHA256.h>
+
+uint16_t TransportKey::calcTransportCode(const mesh::Packet* packet) const {
+  uint16_t code;
+  SHA256 sha;
+  sha.resetHMAC(key, sizeof(key));
+  uint8_t type = packet->getPayloadType();
+  sha.update(&type, 1);
+  sha.update(packet->payload, packet->payload_len);
+  sha.finalizeHMAC(key, sizeof(key), &code, 2);
+  return code;
+}
+
+int TransportKeyStore::loadKeysFor(const char* name, uint16_t id, TransportKey keys[], int max_num) {
+  int n = 0;
+  for (int i = 0; i < num_cache && n < max_num; i++) {  // first, check cache
+    if (cache_ids[i] == id) {
+      keys[n++] = cache_keys[i];
+    }
+  }
+  if (n > 0) return n;   // cache hit!
+
+  if (*name == '#') {   // is a publicly-known hashtag region
+    SHA256 sha;
+    sha.update(name, strlen(name));
+    sha.finalize(&keys[0], sizeof(keys[0].key));
+    n = 1;
+  } else {
+    // TODO:  retrieve from difficult-to-copy keystore
+  }
+
+  // store in cache (if room)
+  for (int i = 0; i < n; i++) {
+    if (num_cache < MAX_TKS_ENTRIES) {
+      cache_ids[num_cache] = id;
+      cache_keys[num_cache] = keys[i];
+      num_cache++;
+    } else {
+      // TODO: evict oldest cache entry
+    }
+  }
+  return n;
+}

src/helpers/TransportKeyStore.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <Arduino.h>   // needed for PlatformIO
+#include <Packet.h>
+#include <helpers/IdentityStore.h>
+
+struct TransportKey {
+  uint8_t key[16];
+
+  uint16_t calcTransportCode(const mesh::Packet* packet) const;
+};
+
+#define MAX_TKS_ENTRIES   16
+
+class TransportKeyStore {
+  uint16_t     cache_ids[MAX_TKS_ENTRIES];
+  TransportKey cache_keys[MAX_TKS_ENTRIES];
+  int num_cache;
+
+public:
+  TransportKeyStore() { num_cache = 0; }
+  int loadKeysFor(const char* name, uint16_t id, TransportKey keys[], int max_num);
+};