Gw Class Reference

Network gateway component. More...

#include <Gw.h>

Inheritance diagram for Gw:

Collaboration diagram for Gw:

Public Member Functions
	Gw (const libconfig::Config &cfg, Phy &phy)
	Default constructor. More...
virtual	~Gw ()
	Default destructor.
void	init ()
	Creates the TUN interface according to params from Cfg.
void	write_pdu_mch (uint32_t lcid, srslte::unique_byte_buffer_t pdu) override
	Handle a MCH PDU. More...
void	add_mch_port (uint32_t lcid, uint32_t port) override
void	write_pdu (uint32_t lcid, srslte::unique_byte_buffer_t pdu) override
int	setup_if_addr (uint32_t lcid, uint8_t pdn_type, uint32_t ip_addr, uint8_t *ipv6_if_id, char *err_str) override
int	apply_traffic_flow_template (const uint8_t &eps_bearer_id, const uint8_t &lcid, const LIBLTE_MME_TRAFFIC_FLOW_TEMPLATE_STRUCT *tft) override
void	set_test_loop_mode (const test_loop_mode_state_t mode, const uint32_t ip_pdu_delay_ms=0) override

Detailed Description

Network gateway component.

Creates a TUN network interface, and writes the received MCH PDU contents out on it.

Definition at line 34 of file Gw.h.

Constructor & Destructor Documentation

Gw()

Gw::Gw ( const libconfig::Config &  cfg, Phy &  phy  )

inline

Default constructor.

Parameters

cfg	Config singleton reference
phy	PHY reference

Definition at line 42 of file Gw.h.

      : _cfg(cfg)
        , _phy(phy)
      {}

Member Function Documentation

write_pdu_mch()

void Gw::write_pdu_mch ( uint32_t  lcid, srslte::unique_byte_buffer_t  pdu  )

override

Handle a MCH PDU.

Verifies the contents start with an IP header, checks the IP header checksum and corrects it if necessary, and writes the packet out to the TUN interface.

Definition at line 36 of file Gw.cpp.

                                                                    {
  char* err_str = nullptr;
  if (pdu->N_bytes > 2) {
    spdlog::debug("RX MCH PDU ({} B). Stack latency: {} us", pdu->N_bytes, pdu->get_latency_us());
 
    if (_tun_fd < 0) {
      spdlog::warn("TUN/TAP not up - dropping gw RX message\n");
    } else {
      auto ip_hdr = reinterpret_cast<iphdr*>(pdu->msg);
      if (ip_hdr->protocol == 17 /*UDP*/) {
        auto udp_hdr = reinterpret_cast<udphdr*>(pdu->msg + 4U * ip_hdr->ihl);
        char dest[INET6_ADDRSTRLEN] = "";   // NOLINT
        inet_ntop(AF_INET, (const void*)&ip_hdr->daddr, dest, sizeof(dest));
 
        _phy.set_dest_for_lcid(lcid, std::string(dest) + ":" + std::to_string(ntohs(udp_hdr->dest)));
 
        auto ptr = reinterpret_cast<uint16_t*>(ip_hdr);
        int32_t sum = 0;
        sum += *ptr++;   // ihl / version / dscp
        sum += *ptr++;   // total len
        sum += *ptr++;   // id
        sum += *ptr++;   // frag offset
        sum += *ptr++;   // ttl + protocol
        ptr++;           // skip checksum
        sum += *ptr++;   // src
        sum += *ptr++;   // src
        sum += *ptr++;   // dst
        sum += *ptr;     // dst
 
        sum = (sum >> 16) + (sum & 0xffff);
        sum += (sum >> 16);
 
        uint16_t chk = ~sum;
        if (ip_hdr->check != chk) {
          spdlog::info("Wrong IP header checksum {}, should be {}. Correcting.", ip_hdr->check, chk);
          ip_hdr->check = chk;
        }
      }
 
      _wr_mutex.lock();
      int n = write(_tun_fd, pdu->msg, pdu->N_bytes);
      _wr_mutex.unlock();
 
      if (n > 0 && (pdu->N_bytes != static_cast<uint32_t>(n))) {
        spdlog::warn("DL TUN/TAP short write");
      }
      if (n == 0) {
        spdlog::warn("DL TUN/TAP 0 write");
      }
      if (n < 0) {
        err_str = strerror(errno);
        spdlog::warn("DL TUN/TAP write error  {}", err_str);
      }
    }
  }
}

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The documentation for this class was generated from the following files:

• src/Gw.h
• src/Gw.cpp