Add hw1

Author: 5teven1in

hw1/Makefile

@@ -0,0 +1,17 @@
+CXX	= g++
+CFLAGS	= -Wall -g -std=c++17
+
+PROGS	= hw1
+
+all: $(PROGS)
+
+%: %.cpp
+	$(CXX) -o $@ $(CFLAGS) $< $(LDFLAGS)
+
+.PHONY: clean test
+
+clean:
+	rm -f *~ $(PROGS)
+
+test: $(PROGS)
+	sudo ./$<

hw1/hw1.cpp

@@ -0,0 +1,241 @@
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <vector>
+#include <map>
+#include <regex>
+#include <getopt.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <sys/stat.h>
+
+#define PB push_back
+
+using namespace std;
+
+typedef vector<string> VS;
+typedef vector<int> VI;
+
+char optstring[] = "tu";
+
+struct option longopts[] = {
+    {"tcp", no_argument, NULL, 't'},
+    {"udp", no_argument, NULL, 'u'},
+    {NULL, no_argument, NULL, 0}
+};
+
+bool is_v6 = false;
+bool is_tcp = true;
+
+string nettype[] = {"udp", "udp6", "tcp", "tcp6"};
+
+struct netstat {
+    int ty;
+    VS s;
+    void print() {
+        cout << setiosflags(ios::left) << setw(6)
+            << nettype[ty]
+            << setw(24)
+            << s[0] + ":" + s[1]
+            << setw(24)
+            << s[2] + ":" + s[3]
+            << s[4] + "/" + s[5] << endl;
+    }
+};
+
+vector<netstat> tcps, udps;
+//   inode, pid
+map<string, string> map2pid;
+//     pid, cmd
+map<string, string> map2cmd;
+string filter;
+
+void list(const string name) {
+    cout << "List of " << name << " connections:" << endl;
+    cout << setiosflags(ios::left) << setw(6)
+        << "Proto" << setw(24)
+        << "Local Address" << setw(24)
+        << "Foreign Address" 
+        << "PID/Program name and arguments" << endl;
+}
+
+VS split(const string &s, const char d = '\0') {
+    VS res;
+    stringstream ss(s);
+    string item;
+    if (d)
+        while (getline(ss, item, d)) res.PB(item);
+    else
+        while (ss >> item) res.PB(item);
+    return res;
+}
+
+void h2i(const string &s, auto &x) {
+    stringstream ss;
+    ss << hex << s;
+    ss >> x;
+}
+
+bool recmp(const string &s, const string &pat) {
+    regex re(pat);
+    return regex_search(s, re);
+}
+
+string get_addr(const string &s) {
+    if (is_v6) {
+        struct sockaddr_in6 sa;
+        for (int i = 0; i < 4; i++) {
+            h2i(s.substr(i * 8, 8), sa.sin6_addr.s6_addr32[i]);
+        }
+        char str[INET6_ADDRSTRLEN + 1] = {0};
+        inet_ntop(AF_INET6, &(sa.sin6_addr), str, INET6_ADDRSTRLEN);
+        return str;
+    }
+    else {
+        struct sockaddr_in sa;
+        h2i(s, sa.sin_addr.s_addr);
+        char str[INET_ADDRSTRLEN + 1] = {0};
+        inet_ntop(AF_INET, &(sa.sin_addr), str, INET_ADDRSTRLEN);
+        return str;
+    }
+}
+
+string get_port(const string &s) {
+    int port;
+    h2i(s, port);
+    return port ? to_string(port) : "*";
+}
+
+VS convert(const string &s) {
+    VS tmp = split(s, ':'), res;
+    res.PB(get_addr(tmp[0]));
+    res.PB(get_port(tmp[1]));
+    return res;
+}
+
+VS list_dir(const string &path) {
+    VS res;
+    DIR *dirp = opendir(path.c_str());
+    if (dirp == NULL) return res;
+    struct dirent *dp;
+    while ((dp = readdir(dirp)) != NULL) {
+        res.PB(dp->d_name);
+    }
+    closedir(dirp);
+    return res;
+}
+
+int get_sockinode(const string &path) {
+    struct stat sb;
+    if (stat(path.c_str(), &sb) == -1) {
+        return -1;
+    }
+    return (sb.st_mode & S_IFMT) == S_IFSOCK ? sb.st_ino : -1;
+}
+
+string get_cmd(const string &path) {
+    ifstream fin(path);
+    string cmd;
+    getline(fin, cmd);
+    for (auto &x : cmd) {
+        if (x == '\0') x = ' ';
+    }
+    fin.close();
+    return cmd;
+}
+
+void build_map() {
+    string proc = "/proc/";
+    VS pids = list_dir(proc);
+    for (auto &pid : pids) {
+        string fd_path = proc + pid + "/fd/";
+        string cmd = get_cmd(proc + pid + "/cmdline");
+        if (cmd == "") continue;
+        map2cmd[pid] = cmd;
+        VS items = list_dir(fd_path);
+        for (auto &x : items) {
+            int inode = get_sockinode(fd_path + x);
+            if (inode != -1) {
+                map2pid[to_string(inode)] = pid;
+            }
+        }
+    }
+}
+
+void parse(const string &path) {
+    ifstream fin(path);
+    string tmp;
+    getline(fin, tmp);      // don't need the first line
+    while (getline(fin, tmp)) {
+        VS v = split(tmp);
+        VS lo = convert(v[1]), fo = convert(v[2]);
+        string pid = map2pid[v[9]];
+        string cmd = map2cmd[pid];
+        netstat n{(is_tcp << 1) | is_v6, {lo[0], lo[1], fo[0], fo[1], pid, cmd}};
+        is_tcp ? tcps.PB(n) : udps.PB(n);
+    }
+    fin.close();
+}
+
+void list_tcp() {
+    is_tcp = true;
+    is_v6 = false;
+    parse("/proc/net/tcp");
+    is_v6 = true;
+    parse("/proc/net/tcp6");
+    list("TCP");
+    for (auto &x : tcps) {
+        if (filter == "" || recmp(x.s[5], filter))
+            x.print();
+    }
+    cout << endl;
+}
+
+void list_udp() {
+    is_tcp = false;
+    is_v6 = false;
+    parse("/proc/net/udp");
+    is_v6 = true;
+    parse("/proc/net/udp6");
+    list("UDP");
+    for (auto &x : udps) {
+        if (filter == "" || recmp(x.s[5], filter))
+            x.print();
+    }
+    cout << endl;
+}
+
+int main(int argc, char* argv[]) {
+    bool list_t = false, list_u = false;
+    int c;
+    while ((c = getopt_long(argc, argv, optstring, longopts, NULL)) != -1) {
+        switch (c) {
+            case 't':
+                list_t = true;
+                break;
+            case 'u':
+                list_u = true;
+                break;
+            default:
+                cout << "Usage: ./hw1 [-t|--tcp] [-u|--udp] [filter-string]" << endl;
+                return 1;
+        }
+    }
+    argc -= optind;
+    argv += optind;
+    if (argv[0] != NULL) filter = argv[0];
+    build_map();
+    if (list_t | list_u) {
+        if (list_t) list_tcp();
+        if (list_u) list_udp();
+    }
+    else {
+        list_tcp();
+        list_udp();
+    }
+    return 0;
+}