diff options
Diffstat (limited to 'src/hooks/dhcp/bootp/bootp_callouts.cc')
| -rw-r--r-- | src/hooks/dhcp/bootp/bootp_callouts.cc | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/src/hooks/dhcp/bootp/bootp_callouts.cc b/src/hooks/dhcp/bootp/bootp_callouts.cc new file mode 100644 index 0000000..688db70 --- /dev/null +++ b/src/hooks/dhcp/bootp/bootp_callouts.cc @@ -0,0 +1,207 @@ +// Copyright (C) 2019-2020 Internet Systems Consortium, Inc. ("ISC") +// +// This Source Code Form is subject to the terms of the Mozilla Public +// License, v. 2.0. If a copy of the MPL was not distributed with this +// file, You can obtain one at http://mozilla.org/MPL/2.0/. + +#include <config.h> + +#include <bootp_log.h> +#include <hooks/hooks.h> +#include <dhcp/pkt4.h> +#include <stats/stats_mgr.h> + +#include <vector> + +using namespace isc; +using namespace isc::bootp; +using namespace isc::dhcp; +using namespace isc::hooks; +using namespace isc::log; +using namespace isc::stats; + +namespace { + +// DHCP Specific options listed in RFC 1533 section 9 and with a code name +// beginning by DHO_DHCP_. +const std::vector<uint16_t> DHCP_SPECIFIC_OPTIONS = { + DHO_DHCP_REQUESTED_ADDRESS, + DHO_DHCP_LEASE_TIME, + DHO_DHCP_OPTION_OVERLOAD, + DHO_DHCP_MESSAGE_TYPE, + DHO_DHCP_SERVER_IDENTIFIER, + DHO_DHCP_PARAMETER_REQUEST_LIST, + DHO_DHCP_MESSAGE, + DHO_DHCP_MAX_MESSAGE_SIZE, + DHO_DHCP_RENEWAL_TIME, + DHO_DHCP_REBINDING_TIME, + DHO_DHCP_CLIENT_IDENTIFIER +}; + +// Size of the BOOTP space for vendor extensions. +const size_t BOOT_VENDOR_SPACE_SIZE = 64; + +// Minimum size of a BOOTP message. +const size_t BOOT_MIN_SIZE = Pkt4::DHCPV4_PKT_HDR_LEN + BOOT_VENDOR_SPACE_SIZE; + +// Check as compile time it is really 300! +static_assert(BOOT_MIN_SIZE == 300, "BOOT_MIN_SIZE is not 300"); + +} // end of anonymous namespace. + +// Functions accessed by the hooks framework use C linkage to avoid the name +// mangling that accompanies use of the C++ compiler as well as to avoid +// issues related to namespaces. +extern "C" { + +/// @brief This callout is called at the "buffer4_receive" hook. +/// +/// Ignore DHCP and BOOTREPLY messages. +/// Remaining packets should be BOOTP requests so add the BOOTP client class +/// and set the message type to DHCPREQUEST. +/// +/// @param handle CalloutHandle. +/// +/// @return 0 upon success, non-zero otherwise. +int buffer4_receive(CalloutHandle& handle) { + CalloutHandle::CalloutNextStep status = handle.getStatus(); + if (status == CalloutHandle::NEXT_STEP_DROP) { + return (0); + } + + // Get the received unpacked message. + Pkt4Ptr query; + handle.getArgument("query4", query); + + try { + if (handle.getStatus() != CalloutHandle::NEXT_STEP_SKIP) { + query->unpack(); + } + + // Not DHCP query nor BOOTP response? + if ((query->getType() == DHCP_NOTYPE) && + (query->getOp() == BOOTREQUEST)) { + + query->addClass("BOOTP"); + query->setType(DHCPREQUEST); + + LOG_DEBUG(bootp_logger, DBGLVL_TRACE_BASIC, BOOTP_BOOTP_QUERY) + .arg(query->getLabel()); + } + } catch (const SkipRemainingOptionsError& ex) { + // An option failed to unpack but we are to attempt to process it + // anyway. Log it and let's hope for the best. + LOG_DEBUG(bootp_logger, DBGLVL_TRACE_BASIC, + BOOTP_PACKET_OPTIONS_SKIPPED) + .arg(ex.what()); + } catch (const std::exception& ex) { + // Failed to parse the packet. + LOG_DEBUG(bootp_logger, DBGLVL_TRACE_BASIC, + BOOTP_PACKET_UNPACK_FAILED) + .arg(query->getRemoteAddr().toText()) + .arg(query->getLocalAddr().toText()) + .arg(query->getIface()) + .arg(ex.what()); + + // Increase the statistics of parse failures and dropped packets. + StatsMgr::instance().addValue("pkt4-parse-failed", + static_cast<int64_t>(1)); + StatsMgr::instance().addValue("pkt4-receive-drop", + static_cast<int64_t>(1)); + + handle.setStatus(CalloutHandle::NEXT_STEP_DROP); + + return (0); + } + + // Avoid to unpack it a second time! + handle.setStatus(CalloutHandle::NEXT_STEP_SKIP); + + return (0); +} + +/// @brief This callout is called at the "pkt4_send" hook. +/// +/// Remove DHCP specific options and pad the buffer to 300 octets. +/// +/// @param handle CalloutHandle. +/// +/// @return 0 upon success, non-zero otherwise. +int pkt4_send(CalloutHandle& handle) { + CalloutHandle::CalloutNextStep status = handle.getStatus(); + if (status == CalloutHandle::NEXT_STEP_DROP) { + return (0); + } + + // Get the query message. + Pkt4Ptr query; + handle.getArgument("query4", query); + + // Check if it is a BOOTP query. + if (!query->inClass("BOOTP")) { + return (0); + } + + // Get the response message. + Pkt4Ptr response; + handle.getArgument("response4", response); + + if (status == CalloutHandle::NEXT_STEP_SKIP) { + isc_throw(InvalidOperation, "packet pack already handled"); + } + + for (uint16_t code : DHCP_SPECIFIC_OPTIONS) { + while (response->delOption(code)) + ; + } + + // Pack the response. + try { + LOG_DEBUG(bootp_logger, DBGLVL_TRACE_BASIC, BOOTP_PACKET_PACK) + .arg(response->getLabel()); + response->pack(); + + // The pack method adds a DHO_END option at the end. + isc::util::OutputBuffer& buffer = response->getBuffer(); + size_t size = buffer.getLength(); + if (size < BOOT_MIN_SIZE) { + size_t delta = BOOT_MIN_SIZE - size; + std::vector<uint8_t> zeros(delta, 0); + buffer.writeData(&zeros[0], delta); + } + } catch (const std::exception& ex) { + LOG_ERROR(bootp_logger, BOOTP_PACKET_PACK_FAIL) + .arg(response->getLabel()) + .arg(ex.what()); + } + + // Avoid to pack it a second time! + handle.setStatus(CalloutHandle::NEXT_STEP_SKIP); + + return (0); +} + +/// @brief This function is called when the library is loaded. +/// +/// @return always 0. +int load(LibraryHandle& /* handle */) { + LOG_INFO(bootp_logger, BOOTP_LOAD); + return (0); +} + +/// @brief This function is called when the library is unloaded. +/// +/// @return always 0. +int unload() { + LOG_INFO(bootp_logger, BOOTP_UNLOAD); + return (0); +} + +/// @brief This function is called to retrieve the multi-threading compatibility. +/// +/// @return 1 which means compatible with multi-threading. +int multi_threading_compatible() { + return (1); +} + +} // end extern "C" |