Add netstat sample application

Author: dtrugman

README.md

@@ -91,6 +91,8 @@ How does that affect `pfs`?
 
 The directory `sample` contains a full blown application that calls all(!) the supported APIs and prints all the information gathered. When compiling the library, the sample applications is compiled as well.
 
+You can find a basic implementation of `netstat` (see `sample/tool_netstat.cpp`) and `lsmod` (see `sample/tool_lsmod.cpp`) that you can easily reuse in your projects.
+
 Anyway, here are some cool (and concise) examples:
 
 **Example 1:** Iterater over all the loaded unsigned or out-of-tree kernel modules

sample/sample.cpp

@@ -37,11 +37,18 @@ int main(int argc, char** argv)
 
         // clang-format off
         auto commands = std::vector<command>{
-            {command("system", "", "Enumerate system-wide information", enum_system)},
-            {command("net", "", "Enumerate network information", enum_net)},
-            {command("tasks", "[task-id]...", "Enumerate running tasks", enum_tasks)},
-            {command("fds", "[task-id]...", "Enumerate fds for a specific task", enum_fds)},
-            {command("lsmod", "[filter]", "Enumerate all loaded modules that match the filter", tool_lsmod)},
+            {command("system", "",
+                    "Enumerate system-wide information", enum_system)},
+            {command("net", "",
+                    "Enumerate network information", enum_net)},
+            {command("tasks", "[task-id]...",
+                    "Enumerate running tasks", enum_tasks)},
+            {command("fds", "[task-id]...",
+                    "Enumerate fds for a specific task", enum_fds)},
+            {command("lsmod", "[filter]",
+                    "Enumerate all loaded modules that match the filter", tool_lsmod)},
+            {command("netstat", "[type] [task-id]",
+                    "Enumerate all sockets of said type for task id", tool_netstat)},
         };
         // clang-format on
 

sample/tool.hpp

@@ -18,5 +18,6 @@
 #define SAMPLE_TOOL_HPP
 
 int tool_lsmod(std::vector<std::string>&& args);
+int tool_netstat(std::vector<std::string>&& args);
 
 #endif // SAMPLE_TOOL_HPP

sample/tool_netstat.cpp

@@ -0,0 +1,97 @@
+/*
+ *  Copyright 2020-present Daniel Trugman
+ *
+ *  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 <regex>
+
+#include "format.hpp"
+#include "log.hpp"
+#include "tool.hpp"
+
+void usage()
+{
+    LOG("Usage: [type] [task-id]");
+    LOG("");
+    LOG("   type        Socket type: tcp, udp, unix");
+    LOG("   task-id     The ID of the task to enumerate");
+    LOG("");
+}
+
+int tool_netstat(std::vector<std::string>&& args)
+{
+    if (args.size() != 2)
+    {
+        usage();
+        return 1;
+    }
+
+    try
+    {
+        LOG("=========================================================");
+        LOG("netstat");
+        LOG("=========================================================");
+
+        static const std::string TCP("tcp");
+        static const std::string UDP("udp");
+
+        std::string type(args[0]);
+        auto id = std::stoi(args[1]);
+
+        pfs::procfs pfs;
+        auto task = pfs.get_task(id);
+
+        // Get all inodes for the given task
+        std::set<ino_t> inodes;
+        auto fds = task.get_fds();
+        for (auto& fd : fds)
+        {
+            inodes.insert(fd.second.get_target_stat().st_ino);
+        }
+
+        auto net = task.get_net();
+        std::vector<pfs::net_socket> sockets;
+        if (type == TCP)
+        {
+            sockets = net.get_tcp();
+        }
+        else if (type == UDP)
+        {
+            sockets = net.get_udp();
+        }
+        else
+        {
+            usage();
+            return 1;
+        }
+
+        std::vector<pfs::net_socket> task_sockets;
+        for (auto& socket : sockets)
+        {
+            if (inodes.find(socket.inode) != inodes.end())
+            {
+                task_sockets.push_back(socket);
+            }
+        }
+
+        print(task_sockets);
+    }
+    catch (const std::runtime_error& ex)
+    {
+        LOG("Error when printing netstat:");
+        LOG(TAB << ex.what());
+    }
+
+    return 0;
+}