container_info.cpp

/*
 *
 * (C) 2018-22 - ntop.org
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

#include "config.h"

#include <stdio.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unordered_map>
#include <vector>
#include <set>
#include <regex>
#include <iostream>

#include <curl/curl.h>
#include <json-c/json.h>

#include "container_info.h"

#define DOCKERD_SOCK_PATH "/var/run/docker.sock"
#define MICROK8S_CTR_PATH "/snap/bin/microk8s.ctr"


// Used to store libcurl partial results
struct response_buffer {
  char *memory;
  size_t size;
};

// #define DEBUG

/* ************************************************* */
// ===== ===== INITIALIZER AND DESTROYER ===== ===== //
/* ************************************************* */
ContainerInfo::ContainerInfo() {
  struct stat s;

  gQueryCache.clear();

  if(stat(MICROK8S_CTR_PATH, &s) == 0)
    strcpy(ctr_path, MICROK8S_CTR_PATH);
  else
    strcpy(ctr_path, "ctr");

  update_namespaces();
}

ContainerInfo::~ContainerInfo() {
  gQueryCache.clear();
  namespaces.clear();
}

/* ********************************************** */
// ===== ===== QUERY TO DOCKER DAEMON ===== ===== //
/* ********************************************** */
static size_t WriteMemoryCallback (void *contents, size_t size, size_t nmemb, void *userp) {
  size_t realsize = size * nmemb;
  struct response_buffer *mem = (struct response_buffer *) userp;

  char *ptr = (char*) realloc(mem->memory, mem->size + realsize + 1);
  if(ptr == NULL) {
    /* out of memory! */
#ifdef DEBUG
    printf("not enough memory (realloc returned NULL)\n");
#endif
    return(0);
  }

  mem->memory = ptr;
  memcpy(&(mem->memory[mem->size]), contents, realsize);
  mem->size += realsize;
  mem->memory[mem->size] = 0;

  return realsize;
}

/* **************************************************** */

/* parse_response - fill a container_info data structure with the information returned by a query to
 * the docker daemon
 * return(0) if no error occurred -1 otherwise
 */
int ContainerInfo::parse_response(const char* buff, ssize_t buffsize, struct container_info *entry) {
  int res_found = 0; // 1 if some info has been found
  struct json_object *jobj=NULL, *jlabel=NULL;
  struct json_object *jdockername, *jconfig, *jpodname, *jcname, *jkubens;
  struct json_tokener *jtok;

#ifdef DEBUG
  printf("[%s:%u] %s(%s)\n", __FILE__, __LINE__, __FUNCTION__, buff);
#endif

  //memset(entry, 0, sizeof(struct container_info));

  // Parsing req to json
  jtok = json_tokener_new();
  jobj = json_tokener_parse_ex(jtok, buff, buffsize);
  // We're not using it anymore, let's cleanup
  json_tokener_free(jtok);

  if(jobj == NULL)
    goto fail;

  // Docker name
  if(json_object_object_get_ex(jobj, "Name", &jdockername)) {
    res_found = 1;
    entry->docker.name = std::string(json_object_get_string(jdockername)+1);
  }

  /*
    "Labels": {
    "io.cri-containerd.kind": "container",
    "io.kubernetes.container.name": "dnsmasq",
    "io.kubernetes.pod.name": "kube-dns-6bfbdd666c-5jbmx",
    "io.kubernetes.pod.namespace": "kube-system",
    "io.kubernetes.pod.uid": "5528e13d-5df8-11e9-a377-001c427c953a"
    },
  */
  
  // Container labels
  if(json_object_object_get_ex(jobj, "Config", &jconfig)) /* json from docker api */
    json_object_object_get_ex(jconfig, "Labels", &jlabel);
  else /* json from containerd api */
    json_object_object_get_ex(jobj, "Labels", &jlabel);

  // Kubernetes info (when available)
  if(jlabel != NULL) {
    // Extracting kube info
    if(json_object_object_get_ex(jlabel, "io.kubernetes.pod.name", &jpodname)) {
      res_found = 1;
      entry->kube.pod = std::string(json_object_get_string(jpodname));
    }

    if(json_object_object_get_ex(jlabel, "io.kubernetes.container.name", &jcname)) {
      res_found = 1;
      entry->kube.name = std::string(json_object_get_string(jcname));
    }

    if(json_object_object_get_ex(jlabel, "io.kubernetes.pod.namespace", &jkubens)) {
      res_found = 1;
      entry->kube.ns  = std::string(json_object_get_string(jkubens));
    }
  }

  if(!res_found)
    goto fail;

  json_object_put(jobj);
  return(0);

 fail:
  if(jobj)
    json_object_put(jobj);

  // memset(entry, 0, sizeof(struct container_info));
  return(-1);
}

/* **************************************************** */

int ContainerInfo::dockerd_update_query_cache(char* t_containerid,
					      struct container_info **t_dqr) {
  int rc = 0;
  CURL *curl_handle;
  CURLcode res;
  char url[101];
  struct response_buffer chunk;
  std::string cgroupid(t_containerid);
  struct stat s;
  struct cache_entry ce;

#ifdef DEBUG
  printf("[%s:%u] %s()\n", __FILE__, __LINE__, __FUNCTION__);
#endif

  (*t_dqr) = NULL;

  if(stat(DOCKERD_SOCK_PATH, &s) == -1)
    return(-1); /* Docker not found */

  // Crafting query
  snprintf(url, sizeof(url), "http://localhost/containers/%s/json", t_containerid);

  // Performing query ----- //
  // Initializing memory buffer
  chunk.memory = (char*) malloc(1);
  chunk.size = 0;
  // Preparing libcurl
  curl_handle = curl_easy_init();
  // URL
  curl_easy_setopt(curl_handle, CURLOPT_URL, url);
  // Callback && Callback arguments
  curl_easy_setopt(curl_handle, CURLOPT_UNIX_SOCKET_PATH, DOCKERD_SOCK_PATH);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);
  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);

  res = curl_easy_perform(curl_handle);

  // Checking for errors
  if(res == CURLE_OK) {
    rc = parse_response(chunk.memory, chunk.size, &ce.content);
  } else {
#ifdef DEBUG
    printf("curl_easy_perform(%s) failed: %s\n", url, curl_easy_strerror(res));
#endif
  }

  // Adding entry to table and pointing argument to entry
  ce.num_uses = 0;
  gQueryCache[t_containerid] = ce;

  *t_dqr = &(gQueryCache[t_containerid].content);

  // Cleaning up
  curl_easy_cleanup(curl_handle);
  free(chunk.memory);
  curl_global_cleanup();

  return(rc);
}

/* **************************************************** */

int ContainerInfo::containerd_update_query_cache (char* t_containerid,
						  struct container_info **t_dqr) {
  FILE *fp;
  char *ns;
  char comm[256];
  char buff[LINE_MAX];
  std::string cgroupid(t_containerid);
  std::set<std::string>::iterator s;
  std::string result;
  struct cache_entry ce;

#ifdef DEBUG
  printf("[%s:%u] %s()\n", __FILE__, __LINE__, __FUNCTION__);
#endif

  (*t_dqr) = NULL;

  try {
    regex_match(cgroupid, std::regex("^([0-9a-zA-Z\\.\\_\\-])*$"));
  } catch (std::regex_error& e) {
#ifdef DEBUG
    printf("[%s:%u] %s()\n", __FILE__, __LINE__, __FUNCTION__);
#endif
    return(-1);
  }

  for(s = namespaces.begin(); s != namespaces.end(); ++s) {
    ns = (char*) (*s).c_str();

    /* ***** ***** SANITIZE THE INPUT ***** ***** */
    // The container id and namespace MUST be sanitized
    // otherwise there's a risk of command injection
    // cgroupid has been already sanitized
    /* ***** ***** ****************** ***** ***** */
    try {
      regex_match(*s, std::regex("^([0-9a-zA-Z\\.\\_\\-])*$"));
    } catch (std::regex_error& e) {
#ifdef DEBUG
      printf("[%s:%u] %s()\n", __FILE__, __LINE__, __FUNCTION__);
#endif
      return(-1);
    }

    snprintf(comm, sizeof(comm), "%s --namespace=%s c info %s 2>/dev/null",
	     ctr_path, ns, t_containerid);

#ifdef DEBUG
    printf("[%s:%u] %s\n", __FILE__, __LINE__, comm);
#endif
    
    // piping to the command
    fp = popen(comm, "r");
    if(fp == NULL) {
#ifdef DEBUG
      printf("containerd interaction failed \n");
#endif
      return -1;
    }

    while(fgets(buff, sizeof(buff), fp)) {
      result += buff;
    }

    pclose(fp);

    // handling json
    if(parse_response(result.c_str(), result.size(), &ce.content) == 0)
      break;
  }

  ce.num_uses = 0;
  gQueryCache[t_containerid] = ce;
  *t_dqr = &(gQueryCache[t_containerid].content);

  return(0);
}

/* **************************************************** */

int ContainerInfo::update_namespaces() {
  FILE *fp;
  int i = 0;
  char ns[LINE_MAX];
  char buf[90];

#ifdef DEBUG
  printf("[%s:%u] %s()\n", __FILE__, __LINE__, __FUNCTION__);
#endif

  namespaces.clear();

  snprintf(buf, sizeof(buf), "%s namespace ls 2>/dev/null", ctr_path);

#ifdef DEBUG
  printf("[%s:%u] %s\n", __FILE__, __LINE__, buf);
#endif
  
  if((fp = popen(buf, "r")) == NULL)
    return(-1);

  while(fgets(ns, sizeof(ns), fp) != NULL) {
    char *space;

    if(i == 0) /* Fs line is the title */ {
      i++;
      continue;
    }

    if((space = strchr(ns, ' ')) != NULL)
      space[0] = '\0';

#ifdef DEBUG
    printf("[%s:%u] Found namespace %s\n", __FILE__, __LINE__, space);
#endif

    namespaces.insert(ns);
  }

  pclose(fp);
  return(0);
}

/* **************************************************** */

/* *********************************** */
// ===== ===== CACHE CHECK ===== ===== //
/* *********************************** */
/*
 * container_id_find_in_cache - check if containers info have been cached
 * returns -1 if the query has not been cached 0 if some info are available
 *  1 for dummy keys
 */
int ContainerInfo::container_id_find_in_cache(char* t_containerid,
					      struct container_info **t_dqs) {
  std::string cgroupid(t_containerid);
  std::unordered_map<std::string, struct cache_entry>::iterator res = gQueryCache.find(cgroupid);

  if(res != gQueryCache.end()) {
    *t_dqs = &(res->second.content);
    res->second.num_uses++;

    return(0);
  } else
    return(-1);
}

/* **************************************************** */

void ContainerInfo::clean_cache() {
  std::unordered_map<std::string, struct cache_entry>::iterator it;

  for(it = gQueryCache.begin(); it != gQueryCache.end();) {
    struct cache_entry ce = it->second;

    if(ce.num_uses == 0)
      it = gQueryCache.erase(it);
    else {
      ce.num_uses = 0;
      it++;
    }
  }
}

/* **************************************************** */

int ContainerInfo::get_container_info(char* t_containerId, struct container_info **t_dqr) {
  int res;
  static time_t last = time(NULL);
  time_t now;

#ifdef DEBUG
  printf("[%s:%u] %s(%s)\n", __FILE__, __LINE__, __FUNCTION__, t_containerId);
#endif

  if((t_containerId[0] == '\0') || (strcmp(t_containerId, "/") == 0))
    return(-1);

  now = time(NULL);
  
  if(difftime(now, last) > REFRESH_TIME /* Seconds */ ) {
    int rc;
    clean_cache();
    namespaces.clear();
    rc = update_namespaces();
    last = now;

    if(rc == -1) return(rc);
  }

  res = container_id_find_in_cache(t_containerId, t_dqr);
  if(res != -1) /* Item is cached */
    return(res);

  // Dockerd
  res = dockerd_update_query_cache(t_containerId, t_dqr);

  // Containerd interaction
  if(res != 0)
    res = containerd_update_query_cache(t_containerId, t_dqr);

  return(res);
}