face: introduce PcapHelper class
Change-Id: I26f7d43394e1b17f314c226ca6bce723c2410ae3
Refs: #4011
diff --git a/daemon/face/pcap-helper.hpp b/daemon/face/pcap-helper.hpp
new file mode 100644
index 0000000..5d239ce
--- /dev/null
+++ b/daemon/face/pcap-helper.hpp
@@ -0,0 +1,146 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2017, Regents of the University of California,
+ * Arizona Board of Regents,
+ * Colorado State University,
+ * University Pierre & Marie Curie, Sorbonne University,
+ * Washington University in St. Louis,
+ * Beijing Institute of Technology,
+ * The University of Memphis.
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE. See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef NFD_DAEMON_FACE_PCAP_HELPER_HPP
+#define NFD_DAEMON_FACE_PCAP_HELPER_HPP
+
+#include "core/common.hpp"
+
+#ifndef HAVE_LIBPCAP
+#error "Cannot include this file when libpcap is not available"
+#endif
+
+// forward declarations
+struct pcap;
+typedef pcap pcap_t;
+
+namespace nfd {
+namespace face {
+
+/**
+ * @brief Helper class for dealing with libpcap handles.
+ */
+class PcapHelper : noncopyable
+{
+public:
+ class Error : public std::runtime_error
+ {
+ public:
+ explicit
+ Error(const std::string& what)
+ : std::runtime_error(what)
+ {
+ }
+ };
+
+ /**
+ * @brief Create a libpcap context for live packet capture on a network interface.
+ * @throw Error on any error
+ * @sa pcap_create(3pcap)
+ */
+ explicit
+ PcapHelper(const std::string& interfaceName);
+
+ ~PcapHelper();
+
+ /**
+ * @brief Start capturing packets.
+ * @param dlt The link-layer header type to be used.
+ * @throw Error on any error
+ * @sa pcap_activate(3pcap), pcap_set_datalink(3pcap)
+ */
+ void
+ activate(int dlt);
+
+ /**
+ * @brief Stop capturing and close the handle.
+ * @sa pcap_close(3pcap)
+ */
+ void
+ close();
+
+ /**
+ * @brief Obtain a file descriptor that can be used in calls such as select(2) and poll(2).
+ * @pre activate() has been called.
+ * @return A selectable file descriptor. It is the caller's responsibility to close the fd.
+ * @throw Error on any error
+ * @sa pcap_get_selectable_fd(3pcap)
+ */
+ int
+ getFd() const;
+
+ /**
+ * @brief Get last error message.
+ * @return Human-readable explanation of the last libpcap error.
+ * @warning The behavior is undefined if no error occurred.
+ * @sa pcap_geterr(3pcap)
+ */
+ std::string
+ getLastError() const;
+
+ /**
+ * @brief Get the number of packets dropped by the kernel, as reported by libpcap.
+ * @throw Error on any error
+ * @sa pcap_stats(3pcap)
+ */
+ size_t
+ getNDropped() const;
+
+ /**
+ * @brief Install a BPF filter on the receiving socket.
+ * @param filter Null-terminated string containing the BPF program source.
+ * @pre activate() has been called.
+ * @throw Error on any error
+ * @sa pcap_setfilter(3pcap), pcap-filter(7)
+ */
+ void
+ setPacketFilter(const char* filter) const;
+
+ /**
+ * @brief Read the next packet captured on the interface.
+ * @return If successful, returns a tuple containing a pointer to the received packet
+ * (including the link-layer header) and the size of the packet; the third
+ * element must be ignored. On failure, returns a tuple containing nullptr,
+ * 0, and the reason for the failure.
+ * @warning The returned pointer must not be freed by the caller, and is valid only
+ * until the next call to this function.
+ * @sa pcap_next_ex(3pcap)
+ */
+ std::tuple<const uint8_t*, size_t, std::string>
+ readNextPacket() const;
+
+ operator pcap_t*() const
+ {
+ return m_pcap;
+ }
+
+private:
+ pcap_t* m_pcap;
+};
+
+} // namespace face
+} // namespace nfd
+
+#endif // NFD_DAEMON_FACE_PCAP_HELPER_HPP