e131_packet.cpp

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#include <cstddef>
#include <cstring>
#include "e131.h"
#ifdef USE_NETWORK
#include "esphome/components/network/ip_address.h"
#include "esphome/core/log.h"
#include "esphome/core/util.h"
#include "esphome/core/helpers.h"
 
#include <lwip/igmp.h>
#include <lwip/init.h>
#include <lwip/ip4_addr.h>
#include <lwip/ip_addr.h>
 
namespace esphome {
namespace e131 {
 
static const char *const TAG = "e131";
 
static const uint8_t ACN_ID[12] = {0x41, 0x53, 0x43, 0x2d, 0x45, 0x31, 0x2e, 0x31, 0x37, 0x00, 0x00, 0x00};
static const uint32_t VECTOR_ROOT = 4;
static const uint32_t VECTOR_FRAME = 2;
static const uint8_t VECTOR_DMP = 2;
 
// E1.31 Packet Structure
union E131RawPacket {
  struct {
    // Root Layer
    uint16_t preamble_size;
    uint16_t postamble_size;
    uint8_t acn_id[12];
    uint16_t root_flength;
    uint32_t root_vector;
    uint8_t cid[16];
 
    // Frame Layer
    uint16_t frame_flength;
    uint32_t frame_vector;
    uint8_t source_name[64];
    uint8_t priority;
    uint16_t reserved;
    uint8_t sequence_number;
    uint8_t options;
    uint16_t universe;
 
    // DMP Layer
    uint16_t dmp_flength;
    uint8_t dmp_vector;
    uint8_t type;
    uint16_t first_address;
    uint16_t address_increment;
    uint16_t property_value_count;
    uint8_t property_values[E131_MAX_PROPERTY_VALUES_COUNT];
  } __attribute__((packed));
 
  uint8_t raw[638];
};
 
// We need to have at least one `1` value
// Get the offset of `property_values[1]`
const size_t E131_MIN_PACKET_SIZE = offsetof(E131RawPacket, property_values) + sizeof(uint8_t);
 
bool E131Component::join_igmp_groups_() {
  if (this->listen_method_ != E131_MULTICAST)
    return false;
#if defined(USE_SOCKET_IMPL_BSD_SOCKETS) || defined(USE_SOCKET_IMPL_LWIP_SOCKETS)
  if (this->socket_ == nullptr)
    return false;
#endif
 
  for (auto &entry : this->universe_consumers_) {
    if (!entry.consumers)
      continue;
 
    ip4_addr_t multicast_addr =
        network::IPAddress(239, 255, ((entry.universe >> 8) & 0xff), ((entry.universe >> 0) & 0xff));
 
    err_t err;
    {
      LwIPLock lock;
      err = igmp_joingroup(IP4_ADDR_ANY4, &multicast_addr);
    }
 
    if (err) {
      ESP_LOGW(TAG, "IGMP join for %d universe of E1.31 failed. Multicast might not work.", entry.universe);
    }
  }
 
  return true;
}
 
UniverseConsumer *E131Component::find_universe_(int universe) {
  for (auto &entry : this->universe_consumers_) {
    if (entry.universe == universe)
      return &entry;
  }
  return nullptr;
}
 
void E131Component::join_(int universe) {
  // store only latest received packet for the given universe
  auto *consumer = this->find_universe_(universe);
  if (consumer != nullptr) {
    if (consumer->consumers++ > 0) {
      return;  // we already joined before
    }
  } else {
    this->universe_consumers_.push_back({static_cast<uint16_t>(universe), 1});
  }
 
  if (this->join_igmp_groups_()) {
    ESP_LOGD(TAG, "Joined %d universe for E1.31.", universe);
  }
}
 
void E131Component::leave_(int universe) {
  auto *consumer = this->find_universe_(universe);
  if (consumer == nullptr)
    return;
 
  if (--consumer->consumers > 0) {
    return;  // we have other consumers of the given universe
  }
 
  if (this->listen_method_ == E131_MULTICAST) {
    ip4_addr_t multicast_addr = network::IPAddress(239, 255, ((universe >> 8) & 0xff), ((universe >> 0) & 0xff));
 
    LwIPLock lock;
    igmp_leavegroup(IP4_ADDR_ANY4, &multicast_addr);
  }
 
  ESP_LOGD(TAG, "Left %d universe for E1.31.", universe);
}
 
bool E131Component::packet_(const uint8_t *data, size_t len, int &universe, E131Packet &packet) {
  if (len < E131_MIN_PACKET_SIZE)
    return false;
 
  auto *sbuff = reinterpret_cast<const E131RawPacket *>(data);
 
  if (memcmp(sbuff->acn_id, ACN_ID, sizeof(sbuff->acn_id)) != 0)
    return false;
  if (htonl(sbuff->root_vector) != VECTOR_ROOT)
    return false;
  if (htonl(sbuff->frame_vector) != VECTOR_FRAME)
    return false;
  if (sbuff->dmp_vector != VECTOR_DMP)
    return false;
  if (sbuff->property_values[0] != 0)
    return false;
 
  universe = htons(sbuff->universe);
  packet.count = htons(sbuff->property_value_count);
  if (packet.count > E131_MAX_PROPERTY_VALUES_COUNT)
    return false;
 
  memcpy(packet.values, sbuff->property_values, packet.count);
  return true;
}
 
}  // namespace e131
}  // namespace esphome
#endif