split handler out of main file

Split the ethstats ipmi handler out of the main file as a first step
towards making it testable.

This allows for dependency injection.

Tested: Compiled.
Change-Id: Ic1657aa9c2b7e4bf0018299add8cd70576fae11b
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/Makefile.am b/Makefile.am
index 218ea38..c0e1f35 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -2,7 +2,7 @@
 
 libethstatscmddir = ${libdir}/ipmid-providers
 libethstatscmd_LTLIBRARIES = libethstatscmd.la
-libethstatscmd_la_SOURCES = main.cpp
+libethstatscmd_la_SOURCES = main.cpp ethstats.cpp
 
 libethstatscmd_la_LDFLAGS = \
 	$(LIBIPMID_LIBS) \
diff --git a/ethstats.cpp b/ethstats.cpp
new file mode 100644
index 0000000..b135331
--- /dev/null
+++ b/ethstats.cpp
@@ -0,0 +1,163 @@
+/*
+ * Copyright 2019 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ethstats.hpp"
+
+#include <ipmid/api.h>
+
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
+#include <filesystem>
+#include <fstream>
+#include <map>
+#include <sstream>
+#include <string>
+
+namespace ethstats
+{
+namespace fs = std::filesystem;
+
+// If this changes in the future, there should be some alternative
+// source for the information if possible to provide continuined functionality.
+static const std::map<std::uint8_t, std::string> statLookup = {
+    {RX_BYTES, "rx_bytes"},
+    {RX_COMPRESSED, "rx_compressed"},
+    {RX_CRC_ERRORS, "rx_crc_errors"},
+    {RX_DROPPED, "rx_dropped"},
+    {RX_ERRORS, "rx_errors"},
+    {RX_FIFO_ERRORS, "rx_fifo_errors"},
+    {RX_FRAME_ERRORS, "rx_frame_errors"},
+    {RX_LENGTH_ERRORS, "rx_length_errors"},
+    {RX_MISSED_ERRORS, "rx_missed_errors"},
+    {RX_NOHANDLER, "rx_nohandler"},
+    {RX_OVER_ERRORS, "rx_over_errors"},
+    {RX_PACKETS, "rx_packets"},
+    {TX_ABORTED_ERRORS, "tx_aborted_errors"},
+    {TX_BYTES, "tx_bytes"},
+    {TX_CARRIER_ERRORS, "tx_carrier_errors"},
+    {TX_COMPRESSED, "tx_compressed"},
+    {TX_DROPPED, "tx_dropped"},
+    {TX_ERRORS, "tx_errors"},
+    {TX_FIFO_ERRORS, "tx_fifo_errors"},
+    {TX_HEARTBEAT_ERRORS, "tx_heartbeat_errors"},
+    {TX_PACKETS, "tx_packets"},
+    {TX_WINDOW_ERRORS, "tx_window_errors"},
+};
+
+ipmi_ret_t handleEthStatCommand(ipmi_cmd_t cmd __attribute__((unused)),
+                                const std::uint8_t* reqBuf,
+                                std::uint8_t* replyCmdBuf, size_t* dataLen)
+{
+    auto reqLength = (*dataLen);
+
+    // Verify the reqBuf is the minimum length.
+    // [0] == statistics id
+    // [1] == if_name_length
+    // [2..N] == if_name
+    // In theory the smallest can be a one-letter name. (3 bytes).
+    if (reqLength < sizeof(struct EthStatRequest) + sizeof(std::uint8_t))
+    {
+        std::fprintf(stderr, "*dataLen too small: %u\n",
+                     static_cast<std::uint32_t>(reqLength));
+        return IPMI_CC_REQ_DATA_LEN_INVALID;
+    }
+
+    // using struct prefix due to nature as c-style pod struct.
+    struct EthStatRequest request;
+    std::memcpy(&request, &reqBuf[0], sizeof(request));
+    auto nameLen = static_cast<std::uint32_t>(request.if_name_len);
+
+    if (reqLength < (sizeof(request) + nameLen))
+    {
+        std::fprintf(stderr, "*dataLen too small: %u\n",
+                     static_cast<std::uint32_t>(reqLength));
+        return IPMI_CC_REQ_DATA_LEN_INVALID;
+    }
+
+    // Check the statistic to see if we recognize it.
+    auto stat = statLookup.find(request.statId);
+    if (stat == statLookup.end())
+    {
+        std::fprintf(stderr, "stat not known: 0x%x\n", request.statId);
+        return IPMI_CC_INVALID_FIELD_REQUEST;
+    }
+
+    // The if_name handling plus a few other things was taken from the
+    // CableCheck command implementation.
+    //
+    // Ok, so we know what statistic they want.  Let's validate their
+    // if_name.  The string is length delimited (like dns).
+
+    // Copy the string out of the request buffer.
+    // Maximum length is 256 bytes, excluding the nul-terminator.
+    auto name = std::string(
+        reinterpret_cast<const char*>(&reqBuf[0] + sizeof(request)), nameLen);
+
+    // Minor sanity & security check (of course, I'm less certain if unicode
+    // comes into play here.
+    //
+    // Basically you can't easily inject ../ or /../ into the path below.
+    // Decided to make this more robust, although since it appends to the path
+    // it would limit any exposure.
+    if (name.find("/") != std::string::npos)
+    {
+        std::fprintf(stderr, "Invalid or illegal name: '%s'\n", name.c_str());
+        return IPMI_CC_INVALID_FIELD_REQUEST;
+    }
+
+    // TODO: Transition to using the netlink api.
+    std::ostringstream opath;
+    opath << "/sys/class/net/" << name << "/statistics/" << stat->second;
+    std::string path = opath.str();
+
+    std::error_code ec;
+    if (!fs::exists(path, ec))
+    {
+        std::fprintf(stderr, "Path: '%s' doesn't exist.\n", path.c_str());
+        return IPMI_CC_INVALID_FIELD_REQUEST;
+    }
+    // We're uninterested in the state of ec.
+
+    // Read the file and check the result.
+    // We read the number as int64, then check to make sure it's positive
+    // before casting to uint64.
+    std::uint64_t value = 0;
+    std::ifstream ifs;
+    ifs.exceptions(std::ifstream::failbit);
+
+    try
+    {
+        ifs.open(path);
+        ifs >> value;
+    }
+    catch (std::ios_base::failure& fail)
+    {
+        return IPMI_CC_UNSPECIFIED_ERROR;
+    }
+
+    struct EthStatReply reply;
+    reply.statId = request.statId;
+    reply.value = value;
+
+    // Store the result.
+    std::memcpy(&replyCmdBuf[0], &reply, sizeof(reply));
+    (*dataLen) = sizeof(reply);
+
+    return IPMI_CC_OK;
+}
+
+} // namespace ethstats
diff --git a/ethstats.hpp b/ethstats.hpp
index 12805de..bf6b707 100644
--- a/ethstats.hpp
+++ b/ethstats.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <ipmid/api.h>
+
 #include <cstdint>
 
 namespace ethstats
@@ -10,8 +12,8 @@
  */
 struct EthStatRequest
 {
-    uint8_t statId;
-    uint8_t if_name_len;
+    std::uint8_t statId;
+    std::uint8_t if_name_len;
 } __attribute__((packed));
 
 /**
@@ -19,8 +21,8 @@
  */
 struct EthStatReply
 {
-    uint8_t statId;
-    uint64_t value;
+    std::uint8_t statId;
+    std::uint64_t value;
 } __attribute__((packed));
 
 enum EthernetStatisticsIds
@@ -49,4 +51,17 @@
     TX_WINDOW_ERRORS = 21,
 };
 
+/**
+ * Handle the OEM IPMI EthStat Command.
+ *
+ * @param[in] cmd - the OEM command.
+ * @param[in] reqBuf - the IPMI request buffer.
+ * @param[in,out] replyCmdBuf - the IPMI reply buffer.
+ * @param[in,out] dataLen - the length of the request and reply.
+ * @return the IPMI result code.
+ */
+ipmi_ret_t handleEthStatCommand(ipmi_cmd_t cmd __attribute__((unused)),
+                                const std::uint8_t* reqBuf,
+                                std::uint8_t* replyCmdBuf, size_t* dataLen);
+
 } // namespace ethstats
diff --git a/main.cpp b/main.cpp
index 07c2e1e..59fd9f9 100644
--- a/main.cpp
+++ b/main.cpp
@@ -18,160 +18,10 @@
 
 #include "ethstats.hpp"
 
-#include <ipmid/api.h>
-
-#include <cstdint>
-#include <cstring>
-#include <filesystem>
-#include <fstream>
+#include <cstdio>
 #include <ipmid/iana.hpp>
 #include <ipmid/oemopenbmc.hpp>
 #include <ipmid/oemrouter.hpp>
-#include <map>
-#include <sstream>
-#include <string>
-
-namespace ethstats
-{
-namespace fs = std::filesystem;
-
-// If this changes in the future, there should be some alternative
-// source for the information if possible to provide continuined functionality.
-static const std::map<uint8_t, std::string> statLookup = {
-    {RX_BYTES, "rx_bytes"},
-    {RX_COMPRESSED, "rx_compressed"},
-    {RX_CRC_ERRORS, "rx_crc_errors"},
-    {RX_DROPPED, "rx_dropped"},
-    {RX_ERRORS, "rx_errors"},
-    {RX_FIFO_ERRORS, "rx_fifo_errors"},
-    {RX_FRAME_ERRORS, "rx_frame_errors"},
-    {RX_LENGTH_ERRORS, "rx_length_errors"},
-    {RX_MISSED_ERRORS, "rx_missed_errors"},
-    {RX_NOHANDLER, "rx_nohandler"},
-    {RX_OVER_ERRORS, "rx_over_errors"},
-    {RX_PACKETS, "rx_packets"},
-    {TX_ABORTED_ERRORS, "tx_aborted_errors"},
-    {TX_BYTES, "tx_bytes"},
-    {TX_CARRIER_ERRORS, "tx_carrier_errors"},
-    {TX_COMPRESSED, "tx_compressed"},
-    {TX_DROPPED, "tx_dropped"},
-    {TX_ERRORS, "tx_errors"},
-    {TX_FIFO_ERRORS, "tx_fifo_errors"},
-    {TX_HEARTBEAT_ERRORS, "tx_heartbeat_errors"},
-    {TX_PACKETS, "tx_packets"},
-    {TX_WINDOW_ERRORS, "tx_window_errors"},
-};
-
-/**
- * Handle the OEM IPMI EthStat Command.
- *
- * @param[in] cmd - the OEM command
- * @param[in] reqBuf - The IPMI request buffer.
- * @param[in,out] replyCmdBuf - the IPMI reply buffer.
- * @param[in,out] dataLen - The length of the request and reply.
- * @return the IPMI result code.
- */
-static ipmi_ret_t HandleEthStatCommand(ipmi_cmd_t cmd __attribute__((unused)),
-                                       const uint8_t* reqBuf,
-                                       uint8_t* replyCmdBuf, size_t* dataLen)
-{
-    auto reqLength = (*dataLen);
-
-    // Verify the reqBuf is the minimum length.
-    // [0] == statistics id
-    // [1] == if_name_length
-    // [2..N] == if_name
-    // In theory the smallest can be a one-letter name. (3 bytes).
-    if (reqLength < sizeof(struct EthStatRequest) + sizeof(uint8_t))
-    {
-        std::fprintf(stderr, "*dataLen too small: %u\n",
-                     static_cast<uint32_t>(reqLength));
-        return IPMI_CC_REQ_DATA_LEN_INVALID;
-    }
-
-    // using struct prefix due to nature as c-style pod struct.
-    struct EthStatRequest request;
-    std::memcpy(&request, &reqBuf[0], sizeof(request));
-    auto nameLen = static_cast<uint32_t>(request.if_name_len);
-
-    if (reqLength < (sizeof(request) + nameLen))
-    {
-        std::fprintf(stderr, "*dataLen too small: %u\n",
-                     static_cast<uint32_t>(reqLength));
-        return IPMI_CC_REQ_DATA_LEN_INVALID;
-    }
-
-    // Check the statistic to see if we recognize it.
-    auto stat = statLookup.find(request.statId);
-    if (stat == statLookup.end())
-    {
-        std::fprintf(stderr, "stat not known: 0x%x\n", request.statId);
-        return IPMI_CC_INVALID_FIELD_REQUEST;
-    }
-
-    // The if_name handling plus a few other things was taken from the
-    // CableCheck command implementation.
-    //
-    // Ok, so we know what statistic they want.  Let's validate their
-    // if_name.  The string is length delimited (like dns).
-
-    // Copy the string out of the request buffer.
-    // Maximum length is 256 bytes, excluding the nul-terminator.
-    auto name = std::string(
-        reinterpret_cast<const char*>(&reqBuf[0] + sizeof(request)), nameLen);
-
-    // Minor sanity & security check (of course, I'm less certain if unicode
-    // comes into play here.
-    //
-    // Basically you can't easily inject ../ or /../ into the path below.
-    // Decided to make this more robust, although since it appends to the path
-    // it would limit any exposure.
-    if (name.find("/") != std::string::npos)
-    {
-        std::fprintf(stderr, "Invalid or illegal name: '%s'\n", name.c_str());
-        return IPMI_CC_INVALID_FIELD_REQUEST;
-    }
-
-    // TODO: Transition to using the netlink api.
-    std::ostringstream opath;
-    opath << "/sys/class/net/" << name << "/statistics/" << stat->second;
-    std::string path = opath.str();
-
-    std::error_code ec;
-    if (!fs::exists(path, ec))
-    {
-        std::fprintf(stderr, "Path: '%s' doesn't exist.\n", path.c_str());
-        return IPMI_CC_INVALID_FIELD_REQUEST;
-    }
-    // We're uninterested in the state of ec.
-
-    // Read the file and check the result.
-    // We read the number as int64, then check to make sure it's positive
-    // before casting to uint64.
-    uint64_t value = 0;
-    std::ifstream ifs;
-    ifs.exceptions(std::ifstream::failbit);
-
-    try
-    {
-        ifs.open(path);
-        ifs >> value;
-    }
-    catch (std::ios_base::failure& fail)
-    {
-        return IPMI_CC_UNSPECIFIED_ERROR;
-    }
-
-    struct EthStatReply reply;
-    reply.statId = request.statId;
-    reply.value = value;
-
-    // Store the result.
-    std::memcpy(&replyCmdBuf[0], &reply, sizeof(reply));
-    (*dataLen) = sizeof(reply);
-
-    return IPMI_CC_OK;
-}
 
 void setupGlobalOemEthStats() __attribute__((constructor));
 
@@ -186,7 +36,7 @@
                  oem::googOemNumber, oem::Cmd::ethStatsCmd);
 
     oemRouter->registerHandler(oem::googOemNumber, oem::Cmd::ethStatsCmd,
-                               HandleEthStatCommand);
+                               ethstats::handleEthStatCommand);
 #endif
 
     std::fprintf(stderr,
@@ -194,7 +44,5 @@
                  oem::obmcOemNumber, oem::Cmd::ethStatsCmd);
 
     oemRouter->registerHandler(oem::obmcOemNumber, oem::Cmd::ethStatsCmd,
-                               HandleEthStatCommand);
+                               ethstats::handleEthStatCommand);
 }
-
-} // namespace ethstats