First commit: Sila SNMP Sub Agent and configuration manager

4 files changed, 358 insertions, 0 deletions

diff --git a/snmpcfg/Makefile.am b/snmpcfg/Makefile.am
new file mode 100644
index 0000000..5741fd0
--- /dev/null
+++ b/snmpcfg/Makefile.am
@@ -0,0 +1,41 @@
+bin_PROGRAMS = sila-snmpcfg
+
+nobase_nodist_include_HEADERS = \
+	xyz/openbmc_project/SNMPCfg/server.hpp
+
+sila_snmpcfg_SOURCES = \
+	snmpcfg-server.cpp \
+	xyz/openbmc_project/SNMPCfg/server.cpp 
+
+sila_snmpcfg_CXXFLAGS = \
+	$(SDBUSPLUS_CFLAGS) \
+	$(PHOSPHOR_DBUS_INTERFACES_CFLAGS) \
+	$(PHOSPHOR_LOGGING_CFLAGS)
+sila_snmpcfg_LDADD = \
+	$(SDBUSPLUS_LIBS) \
+	$(PHOSPHOR_DBUS_INTERFACES_LIBS) \
+	$(PHOSPHOR_LOGGING_LIBS)
+
+# Be sure to build needed files before compiling
+BUILT_SOURCES = \
+	xyz/openbmc_project/SNMPCfg/server.cpp \
+	xyz/openbmc_project/SNMPCfg/server.hpp 
+
+CLEANFILES=${BUILT_SOURCES}
+
+xyz/openbmc_project/SNMPCfg/server.cpp: \
+xyz/openbmc_project/SNMPCfg.interface.yaml \
+xyz/openbmc_project/SNMPCfg/server.hpp
+	@mkdir -p $(@D)
+	$(SDBUSPLUSPLUS) -r $(srcdir) interface server-cpp \
+xyz.openbmc_project.SNMPCfg > $@
+
+xyz/openbmc_project/SNMPCfg/server.hpp: \
+xyz/openbmc_project/SNMPCfg.interface.yaml
+	@mkdir -p $(@D)
+	$(SDBUSPLUSPLUS) -r $(srcdir) interface server-header \
+xyz.openbmc_project.SNMPCfg > $@
+
+if HAVE_SYSTEMD
+systemdsystemunit_DATA = sila-snmp-cfg-manager.service
+endif
diff --git a/snmpcfg/sila-snmp-cfg-manager.service.in b/snmpcfg/sila-snmp-cfg-manager.service.in
new file mode 100644
index 0000000..d80b9a6
--- /dev/null
+++ b/snmpcfg/sila-snmp-cfg-manager.service.in
@@ -0,0 +1,13 @@
+[Unit]
+Description=Sila SNMP configuration manager
+After=snmpd.service
+
+[Service]
+ExecStart=@bindir@/sila-snmpcfg
+SyslogIdentifier=sila-snmpcfg
+Restart=always
+Type=dbus
+BusName=xyz.openbmc_project.SNMPCfg
+
+[Install]
+WantedBy=@SYSTEMD_TARGET@
diff --git a/snmpcfg/snmpcfg-server.cpp b/snmpcfg/snmpcfg-server.cpp
new file mode 100644
index 0000000..da76555
--- /dev/null
+++ b/snmpcfg/snmpcfg-server.cpp
@@ -0,0 +1,291 @@
+/**
+ * @brief SNMP Configuration manager
+ *
+ * This file is part of sila-snmp project.
+ *
+ * Copyright (c) 2022 SILA
+ *
+ * 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 <string>
+#include <fstream>
+#include <streambuf>
+
+#include <sdbusplus/server.hpp>
+#include <xyz/openbmc_project/SNMPCfg/server.hpp>
+#include <phosphor-logging/log.hpp>
+#include <phosphor-logging/elog.hpp>
+#include <phosphor-logging/elog-errors.hpp>
+#include <xyz/openbmc_project/Common/error.hpp>
+
+using namespace phosphor::logging;
+using SNMPCfg_inherit = sdbusplus::server::object_t<
+    sdbusplus::xyz::openbmc_project::server::SNMPCfg>;
+
+using InternalFailure =
+    sdbusplus::xyz::openbmc_project::Common::Error::InternalFailure;
+using InvalidArgument =
+    sdbusplus::xyz::openbmc_project::Common::Error::InvalidArgument;
+using Argument = xyz::openbmc_project::Common::InvalidArgument;
+
+static constexpr auto snmpdConf = "/etc/snmp/snmpd.conf";
+static constexpr auto whitespace = " \t";
+
+/**
+ * @brief Check if the string contains the token at the position or after
+ *        several spaces.
+ *
+ * @param[in] str   - string to be checked
+ * @param[in] token - expected token
+ * @param[in/out] pos - start position for checking, will keep the last
+ *                      checked position.
+ *
+ * @return - true if token found.
+ */
+static bool getToken(const std::string& str, const std::string& token,
+                     size_t& pos)
+{
+    pos = str.find_first_not_of(whitespace, pos);
+    if (pos != std::string::npos && 0 == str.compare(pos, token.size(), token))
+    {
+        auto endPos = str.find_first_of(whitespace, pos);
+        if (endPos == std::string::npos || pos + token.size() == endPos)
+        {
+            pos = endPos;
+            return true;
+        }
+    }
+    return false;
+}
+
+class Configurator : public SNMPCfg_inherit
+{
+  public:
+    /**
+     * @brief Configurator object constructor
+     *
+     * @param bus  - DBus connection object reference
+     * @param path - DBus object path
+     */
+    Configurator(sdbusplus::bus::bus& bus, const char* path) :
+        SNMPCfg_inherit(bus, path), bus(bus)
+    {
+        readConfig();
+    }
+
+    std::string community(std::string value) override
+    {
+        static constexpr auto communityMaxLen = 256;
+        static constexpr auto communityMinLen = 1;
+
+        auto communityLen = value.length();
+        if (communityLen < communityMinLen || communityLen > communityMaxLen)
+        {
+            log<level::ERR>("Invalid community name length");
+            elog<InvalidArgument>(Argument::ARGUMENT_NAME("Community"),
+                                  Argument::ARGUMENT_VALUE(value.c_str()));
+        }
+
+        SNMPCfg_inherit::community(value);
+        writeConfig();
+        return value;
+    }
+
+  private:
+    /**
+     * @brief Parse line and get community name
+     *
+     * @param line - the line from configuration file
+     *
+     * @return community name if corresponding statement found
+     *         and nullopt otherwise
+     */
+    std::optional<std::string> getCommunityName(std::string line) const
+    {
+        // Required line should be in format:
+        // 'com2sec readonly  default     <communityName>'
+        size_t pos = 0;
+
+        for (const auto& token : {"com2sec", "readonly", "default"})
+        {
+            if (!getToken(line, token, pos) || pos == std::string::npos)
+            {
+                return std::nullopt;
+            }
+        }
+
+        pos = line.find_first_not_of(whitespace, pos);
+        if (pos == std::string::npos)
+        {
+            return std::nullopt;
+        }
+
+        auto endPos = line.find_last_not_of(whitespace);
+        if (pos < endPos && line[pos] == '"' && line[endPos] == '"')
+        {
+            pos++;
+            endPos--;
+        }
+
+        return (pos <= endPos ? line.substr(pos, endPos - pos + 1)
+                              : std::string{});
+    }
+
+    /**
+     * @brief Read actual settings from configuration file
+     */
+    void readConfig()
+    {
+        std::ifstream fileToRead(snmpdConf, std::ios::in);
+        if (!fileToRead.is_open())
+        {
+            log<level::ERR>("Failed to open SNMP daemon configuration file",
+                            entry("FILE_NAME=%s", snmpdConf));
+            return;
+        }
+
+        std::string line;
+        while (std::getline(fileToRead, line))
+        {
+            auto communityName = getCommunityName(line);
+            if (communityName)
+            {
+                SNMPCfg_inherit::community(*communityName);
+                return;
+            }
+        }
+        log<level::ERR>("Community not found",
+                        entry("FILE_NAME=%s", snmpdConf));
+    }
+
+    /**
+     * @brief Write actual settings to the configuration file.
+     */
+    void writeConfig()
+    {
+        std::string tmpFileName{snmpdConf};
+        tmpFileName += ".tmp";
+
+        std::ifstream fileToRead(snmpdConf, std::ios::in);
+        std::ofstream fileToWrite(tmpFileName, std::ios::out);
+        if (!fileToRead.is_open())
+        {
+            log<level::ERR>("Failed to open SNMP daemon configuration file",
+                            entry("FILE_NAME=%s", snmpdConf));
+            return;
+        }
+
+        if (!fileToWrite.is_open())
+        {
+            log<level::ERR>("Failed to create new configuration file",
+                            entry("FILE_NAME=%s", tmpFileName.c_str()));
+            return;
+        }
+
+        auto value = SNMPCfg_inherit::community();
+        bool isQuoteRequired =
+            (value.find_first_of(whitespace) != std::string::npos);
+        bool updated = false;
+        std::string line;
+        while (std::getline(fileToRead, line))
+        {
+            auto communityName = getCommunityName(line);
+            if (communityName && *communityName != value)
+            {
+                fileToWrite << "com2sec readonly  default\t  "
+                            << (isQuoteRequired ? "\"" : "") << value
+                            << (isQuoteRequired ? "\"" : "") << std::endl;
+                updated = true;
+            }
+            else
+            {
+                fileToWrite << line << std::endl;
+            }
+        }
+        fileToWrite.close();
+        fileToRead.close();
+
+        if (updated)
+        {
+            if (0 != std::rename(tmpFileName.c_str(), snmpdConf))
+            {
+                int error = errno;
+                log<level::ERR>("Failed to update SNMP daemon configuarion",
+                                entry("WHAT=%s", strerror(error)),
+                                entry("FILE_NAME=%s", snmpdConf));
+                elog<InternalFailure>();
+            }
+
+            reloadSnmpDaemon();
+        }
+        else
+        {
+            if (0 != std::remove(tmpFileName.c_str()))
+            {
+                int error = errno;
+                log<level::ERR>("Failed to remove temporary file",
+                                entry("WHAT=%s", strerror(error)),
+                                entry("FILE_NAME=%s", tmpFileName.c_str()));
+            }
+        }
+    }
+
+    sdbusplus::bus::bus& bus;
+
+    /**
+     * @brief Ask SNMP daemon to reread configuration.
+     */
+    void reloadSnmpDaemon()
+    {
+        auto m = bus.new_method_call(
+            "org.freedesktop.systemd1", "/org/freedesktop/systemd1",
+            "org.freedesktop.systemd1.Manager", "ReloadUnit");
+        m.append("snmpd.service", "replace");
+        try
+        {
+            bus.call_noreply(m);
+        }
+        catch (const sdbusplus::exception::SdBusError& e)
+        {
+            log<level::ERR>("Failed to reload SNMP daemon",
+                            entry("WHATE=%s", e.what()));
+            elog<InternalFailure>();
+        }
+    }
+};
+
+/**
+ * @brief Application entry point
+ *
+ * @return exit status
+ */
+int main()
+{
+    constexpr auto path = "/xyz/openbmc_project/snmpcfg";
+
+    auto b = sdbusplus::bus::new_default();
+    sdbusplus::server::manager_t m{b, path};
+
+    b.request_name("xyz.openbmc_project.SNMPCfg");
+    Configurator cfg{b, path};
+
+    while (1)
+    {
+        b.process_discard();
+        b.wait();
+    }
+
+    return 0;
+}
diff --git a/snmpcfg/xyz/openbmc_project/SNMPCfg.interface.yaml b/snmpcfg/xyz/openbmc_project/SNMPCfg.interface.yaml
new file mode 100644
index 0000000..5017f7b
--- /dev/null
+++ b/snmpcfg/xyz/openbmc_project/SNMPCfg.interface.yaml
@@ -0,0 +1,13 @@
+description: >
+  SNMP daemon configuration manager.
+
+properties:
+  - name: Community
+    type: string
+    description: >
+      SNMPv1 and SNMPv2 community that allows read-only (GET and GETNEXT) access
+      to the data providing by SNMP daemon.
+    errors:
+      - xyz.openbmc_project.Common.Error.InternalFailure
+      - xyz.openbmc_project.Common.Error.InvalidArgument
+