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conky/src/libtcp-portmon.cc

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/*
*
* libtcp-portmon.c: tcp port monitoring library.
*
* Copyright (C) 2005-2007 Philip Kovacs pkovacs@users.sourceforge.net
*
* This library 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 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
* USA.
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "libtcp-portmon.h"
#include <cstdio>
#include <cstring>
#include <unordered_map>
#include <vector>
/* -------------------------------------------------------------------
* IMPLEMENTATION INTERFACE
*
* Implementation-specific interface begins here. Clients should not
* manipulate these structures directly, nor call the defined helper
* functions. Use the "Client interface" functions defined at bottom.
* ------------------------------------------------------------------- */
namespace {
/* ------------------------------------------------------------------------
* A single tcp connection
* ------------------------------------------------------------------------ */
struct tcp_connection_t {
/* connection's key in monitor hash */
struct in6_addr local_addr;
struct in6_addr remote_addr;
in_port_t local_port;
in_port_t remote_port;
};
/* hash function for tcp connections */
struct tcp_connection_hash {
size_t operator()(const tcp_connection_t &a) const {
size_t hash = 0;
size_t i;
hash = hash * 47 + a.local_port;
hash = hash * 47 + a.remote_port;
for (i = 0; i < sizeof(a.local_addr.s6_addr); ++i)
hash = hash * 47 + a.local_addr.s6_addr[i];
for (i = 0; i < sizeof(a.remote_addr.s6_addr); ++i)
hash = hash * 47 + a.remote_addr.s6_addr[i];
return hash;
}
};
/* comparison function for tcp connections */
bool operator==(const tcp_connection_t &a, const tcp_connection_t &b) {
return a.local_port == b.local_port && a.remote_port == b.remote_port &&
!std::memcmp(&a.local_addr, &b.local_addr, sizeof(a.local_addr)) &&
!std::memcmp(&a.remote_addr.s6_addr, &b.remote_addr,
sizeof(a.remote_addr));
}
/* ------------------------------------------------------------------------
* A hash table containing tcp connection
*
* The second parameter provides the mechanism for removing connections if
* they are not seen again in subsequent update cycles.
* ------------------------------------------------------------------------ */
typedef std::unordered_map<tcp_connection_t, int, tcp_connection_hash>
connection_hash_t;
/* start and end of port monitor range. Set start=end to monitor a single port
*/
typedef std::pair<in_port_t, in_port_t> port_range_t;
/* hash function for port ranges */
struct port_range_hash {
size_t operator()(const port_range_t &a) const {
return a.first * 47 + a.second;
}
};
typedef std::unordered_map<port_range_t, tcp_port_monitor_t, port_range_hash>
monitor_hash_t;
} // namespace
/* --------------
* A port monitor
* -------------- */
struct _tcp_port_monitor_t {
/* hash table of pointers into connection list */
connection_hash_t hash;
/* array of connection pointers for O(1) peeking
* these point into the hash table*/
std::vector<const tcp_connection_t *> p_peek;
_tcp_port_monitor_t(int max_connections)
: hash(),
p_peek(max_connections,
static_cast<const tcp_connection_t *>(nullptr)) {}
_tcp_port_monitor_t(const _tcp_port_monitor_t &other)
: hash(other.hash),
p_peek(other.p_peek.size(),
static_cast<const tcp_connection_t *>(nullptr)) {
// we must rebuild the peek table because the pointers are no longer valid
rebuild_peek_table();
}
void rebuild_peek_table() {
/* Run through the monitor's connections and rebuild the peek table of
* connection pointers. This is done so peeking into the monitor can be
* done in O(1) time instead of O(n) time for each peek. */
/* zero out the peek array */
std::fill(p_peek.begin(), p_peek.end(),
static_cast<tcp_connection_t *>(nullptr));
size_t i = 0;
for (connection_hash_t::iterator j = hash.begin(); j != hash.end();
++j, ++i) {
p_peek[i] = &j->first;
}
}
private:
// we don't need this atm
const _tcp_port_monitor_t &operator=(const _tcp_port_monitor_t &);
};
/* -----------------------------
* A tcp port monitor collection
* ----------------------------- */
struct _tcp_port_monitor_collection_t {
/* hash table of monitors */
monitor_hash_t hash;
};
namespace {
/* ---------------------------------------
* A port monitor utility function typedef
* --------------------------------------- */
typedef void (*tcp_port_monitor_function_ptr_t)(
monitor_hash_t::value_type &monitor, void *p_void);
void age_tcp_port_monitor(monitor_hash_t::value_type &monitor, void *p_void) {
/* Run through the monitor's connections and decrement the age variable.
* If the age goes negative, we remove the connection from the monitor.
* Function takes O(n) time on the number of connections. */
if (p_void) { /* p_void should be nullptr in this context */
return;
}
for (connection_hash_t::iterator i = monitor.second.hash.begin();
i != monitor.second.hash.end();) {
if (--i->second >= 0)
++i;
else {
/* connection is old. remove connection from the hash. */
/* erase shouldn't invalidate iterators */
monitor.second.hash.erase(i++);
}
}
}
void rebuild_tcp_port_monitor_peek_table(monitor_hash_t::value_type &monitor,
void *p_void) {
if (p_void) { /* p_void should be nullptr in this context */
return;
}
monitor.second.rebuild_peek_table();
}
void show_connection_to_tcp_port_monitor(monitor_hash_t::value_type &monitor,
void *p_void) {
/* The monitor gets to look at each connection to see if it falls within
* the monitor's port range of interest. Connections of interest are first
* looked up in the hash to see if they are already there. If they are, we
* reset the age of the connection so it is not deleted. If the connection
* is not in the hash, we add it, but only if we haven't exceeded the
* maximum connection limit for the monitor.
* The function takes O(1) time. */
tcp_connection_t *p_connection;
if (!p_void) { return; }
/* This p_connection is on caller's stack and not the heap.
* If we are interested, we will create a copy of the connection
* (on the heap) and add it to our list. */
p_connection = (tcp_connection_t *)p_void;
/* inspect the local port number of the connection to see if we're
* interested. */
if ((monitor.first.first <= p_connection->local_port) &&
(p_connection->local_port <= monitor.first.second)) {
/* the connection is in the range of the monitor. */
/* first check the hash to see if the connection is already there. */
connection_hash_t::iterator i = monitor.second.hash.find(*p_connection);
if (i != monitor.second.hash.end()) {
/* it's already in the hash. reset the age of the connection. */
i->second = TCP_CONNECTION_STARTING_AGE;
return;
}
/* Connection is not yet in the hash.
* Add it if max_connections not exceeded. */
if (monitor.second.hash.size() < monitor.second.p_peek.size()) {
monitor.second.hash.insert(connection_hash_t::value_type(
*p_connection, TCP_CONNECTION_STARTING_AGE));
}
}
}
/* ------------------------------------------------------------------------
* Apply a tcp_port_monitor_function_ptr_t function to each port monitor in
* the collection.
* ------------------------------------------------------------------------ */
void for_each_tcp_port_monitor_in_collection(
tcp_port_monitor_collection_t *p_collection,
tcp_port_monitor_function_ptr_t p_function, void *p_function_args) {
if (!p_collection || !p_function) { return; }
/* for each monitor in the collection */
for (monitor_hash_t::iterator i = p_collection->hash.begin();
i != p_collection->hash.end(); ++i) {
/* apply the function with the given arguments */
p_function(*i, p_function_args);
}
}
const unsigned char prefix_4on6[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0xff, 0xff};
union sockaddr_in46 {
struct sockaddr_in sa4;
struct sockaddr_in6 sa6;
struct sockaddr sa;
};
/* checks whether the address is a IPv4-mapped IPv6 address */
bool is_4on6(const struct in6_addr *addr) {
return !std::memcmp(&addr->s6_addr, prefix_4on6, sizeof(prefix_4on6));
}
/* converts the address to appropriate textual representation (IPv6, IPv4 or
* fqdn) */
void print_host(char *p_buffer, size_t buffer_size, const struct in6_addr *addr,
int fqdn) {
union sockaddr_in46 sa;
socklen_t slen;
std::memset(&sa, 0, sizeof(sa));
if (is_4on6(addr)) {
sa.sa4.sin_family = AF_INET;
std::memcpy(&sa.sa4.sin_addr.s_addr, &addr->s6_addr[12], 4);
slen = sizeof(sa.sa4);
} else {
sa.sa6.sin6_family = AF_INET6;
std::memcpy(&sa.sa6.sin6_addr, addr, sizeof(struct in6_addr));
slen = sizeof(sa.sa6);
}
getnameinfo(&sa.sa, slen, p_buffer, buffer_size, nullptr, 0,
fqdn ? 0 : NI_NUMERICHOST);
}
/* converts the textual representation of an IPv4 or IPv6 address to struct
* in6_addr */
void string_to_addr(struct in6_addr *addr, const char *p_buffer) {
size_t i;
if (std::strlen(p_buffer) < 32) { // IPv4 address
i = sizeof(prefix_4on6);
std::memcpy(addr->s6_addr, prefix_4on6, i);
} else {
i = 0;
}
for (; i < sizeof(addr->s6_addr); i += 4, p_buffer += 8) {
std::sscanf(p_buffer, "%8x", (unsigned *)&addr->s6_addr[i]);
}
}
/* adds connections from file to the collection */
void process_file(tcp_port_monitor_collection_t *p_collection,
const char *file) {
std::FILE *fp;
char buf[256];
char local_addr[40];
char remote_addr[40];
tcp_connection_t conn;
unsigned long inode, uid, state;
if ((fp = std::fopen(file, "r")) == nullptr) { return; }
/* ignore field name line */
if (std::fgets(buf, 255, fp) == nullptr) {
std::fclose(fp);
return;
}
/* read all tcp connections */
while (std::fgets(buf, sizeof(buf), fp) != nullptr) {
if (std::sscanf(buf,
"%*d: %39[0-9a-fA-F]:%hx %39[0-9a-fA-F]:%hx %lx %*x:%*x "
"%*x:%*x %*x %lu %*d %lu",
local_addr, &conn.local_port, remote_addr,
&conn.remote_port, (unsigned long *)&state,
(unsigned long *)&uid, (unsigned long *)&inode) != 7) {
std::fprintf(stderr, "%s: bad file format\n", file);
}
/** TCP_ESTABLISHED equals 1, but is not (always??) included **/
// if ((inode == 0) || (state != TCP_ESTABLISHED)) {
if ((inode == 0) || (state != 1)) { continue; }
string_to_addr(&conn.local_addr, local_addr);
string_to_addr(&conn.remote_addr, remote_addr);
/* show the connection to each port monitor. */
for_each_tcp_port_monitor_in_collection(
p_collection, &show_connection_to_tcp_port_monitor, (void *)&conn);
}
std::fclose(fp);
}
} // namespace
/* ----------------------------------------------------------------------
* CLIENT INTERFACE
*
* Clients should call only those functions below this line.
* ---------------------------------------------------------------------- */
/* ----------------------------------
* Client operations on port monitors
* ---------------------------------- */
/* Clients use this function to get connection data from the indicated
* port monitor.
* The requested monitor value is copied into a client-supplied char buffer.
* Returns 0 on success, -1 otherwise. */
int peek_tcp_port_monitor(const tcp_port_monitor_t *p_monitor, int item,
int connection_index, char *p_buffer,
size_t buffer_size) {
struct sockaddr_in sa;
if (!p_monitor || !p_buffer || connection_index < 0) { return -1; }
std::memset(p_buffer, 0, buffer_size);
std::memset(&sa, 0, sizeof(sa));
sa.sin_family = AF_INET;
/* if the connection index is out of range, we simply return with no error,
* having first cleared the client-supplied buffer. */
if ((item != COUNT) &&
(connection_index >= ssize_t(p_monitor->hash.size()))) {
return 0;
}
switch (item) {
case COUNT:
std::snprintf(p_buffer, buffer_size, "%u",
unsigned(p_monitor->hash.size()));
break;
case REMOTEIP:
print_host(p_buffer, buffer_size,
&p_monitor->p_peek[connection_index]->remote_addr, 0);
break;
case REMOTEHOST:
print_host(p_buffer, buffer_size,
&p_monitor->p_peek[connection_index]->remote_addr, 1);
break;
case REMOTEPORT:
std::snprintf(p_buffer, buffer_size, "%d",
p_monitor->p_peek[connection_index]->remote_port);
break;
case REMOTESERVICE:
sa.sin_port = htons(p_monitor->p_peek[connection_index]->remote_port);
getnameinfo((struct sockaddr *)&sa, sizeof(struct sockaddr_in), nullptr,
0, p_buffer, buffer_size, NI_NUMERICHOST);
break;
case LOCALIP:
print_host(p_buffer, buffer_size,
&p_monitor->p_peek[connection_index]->local_addr, 0);
break;
case LOCALHOST:
print_host(p_buffer, buffer_size,
&p_monitor->p_peek[connection_index]->local_addr, 1);
break;
case LOCALPORT:
std::snprintf(p_buffer, buffer_size, "%d",
p_monitor->p_peek[connection_index]->local_port);
break;
case LOCALSERVICE:
sa.sin_port = htons(p_monitor->p_peek[connection_index]->local_port);
getnameinfo((struct sockaddr *)&sa, sizeof(struct sockaddr_in), nullptr,
0, p_buffer, buffer_size, NI_NUMERICHOST);
break;
default:
return -1;
}
return 0;
}
/* --------------------------------
* Client operations on collections
* -------------------------------- */
/* Create a monitor collection. Do this one first. */
tcp_port_monitor_collection_t *create_tcp_port_monitor_collection(void) {
return new tcp_port_monitor_collection_t();
}
/* Destroy the monitor collection (and the monitors inside).
* Do this one last. */
void destroy_tcp_port_monitor_collection(
tcp_port_monitor_collection_t *p_collection) {
delete p_collection;
}
/* Updates the tcp statistics for all monitors within a collection */
void update_tcp_port_monitor_collection(
tcp_port_monitor_collection_t *p_collection) {
if (!p_collection) { return; }
process_file(p_collection, "/proc/net/tcp");
process_file(p_collection, "/proc/net/tcp6");
/* age the connections in all port monitors. */
for_each_tcp_port_monitor_in_collection(p_collection, &age_tcp_port_monitor,
nullptr);
/* rebuild the connection peek tables of all monitors
* so clients can peek in O(1) time */
for_each_tcp_port_monitor_in_collection(
p_collection, &rebuild_tcp_port_monitor_peek_table, nullptr);
}
/* Creation of reduntant monitors is silently ignored */
int insert_new_tcp_port_monitor_into_collection(
tcp_port_monitor_collection_t *p_collection, in_port_t port_range_begin,
in_port_t port_range_end, tcp_port_monitor_args_t *p_creation_args) {
if (!p_collection) { return -1; }
p_collection->hash.insert(monitor_hash_t::value_type(
port_range_t(port_range_begin, port_range_end),
tcp_port_monitor_t(p_creation_args->max_port_monitor_connections)));
return 0;
}
/* Clients need a way to find monitors */
tcp_port_monitor_t *find_tcp_port_monitor(
tcp_port_monitor_collection_t *p_collection, in_port_t port_range_begin,
in_port_t port_range_end) {
if (!p_collection) { return nullptr; }
/* is monitor in hash? */
monitor_hash_t::iterator i =
p_collection->hash.find(port_range_t(port_range_begin, port_range_end));
return i == p_collection->hash.end() ? nullptr : &i->second;
}
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