Replace ConnList linked list with multiset

Keeping a sorted multi-set allows faster search by source /
source+destination address.

Fixes O(n^2) complexity when handling a lot of connections (now it's
O(n log n)).

src/connection.cpp

@@ -33,7 +33,7 @@
 #include "nethogs.h"
 #include "process.h"
 
-ConnList *connections = NULL;
+ConnList connections;
 extern Process *unknownudp;
 
 void PackList::add(Packet *p) {
@@ -78,7 +78,6 @@ u_int64_t PackList::sumanddel(timeval t) {
 /* packet may be deleted by caller */
 Connection::Connection(Packet *packet) {
   assert(packet != NULL);
-  connections = new ConnList(this, connections);
   sent_packets = new PackList();
   recv_packets = new PackList();
   sumSent = 0;
@@ -96,6 +95,7 @@ Connection::Connection(Packet *packet) {
     recv_packets->add(packet);
     refpacket = packet->newInverted();
   }
+  connections.insert(this);
   lastpacket = packet->time.tv_sec;
   if (DEBUG)
     std::cout << "New reference packet created at " << refpacket << std::endl;
@@ -104,6 +104,13 @@ Connection::Connection(Packet *packet) {
 Connection::~Connection() {
   if (DEBUG)
     std::cout << "Deleting connection" << std::endl;
+  auto r = connections.equal_range(this);
+  for (auto it = r.first; it != r.second; ++it) {
+    if (*it == this) {
+      connections.erase(it);
+      break;
+    }
+  }
   /* refpacket is not a pointer to one of the packets in the lists
    * so deleted */
   delete (refpacket);
@@ -111,24 +118,6 @@ Connection::~Connection() {
     delete sent_packets;
   if (recv_packets != NULL)
     delete recv_packets;
-
-  ConnList *curr_conn = connections;
-  ConnList *prev_conn = NULL;
-  while (curr_conn != NULL) {
-    if (curr_conn->getVal() == this) {
-      ConnList *todelete = curr_conn;
-      curr_conn = curr_conn->getNext();
-      if (prev_conn == NULL) {
-        connections = curr_conn;
-      } else {
-        prev_conn->setNext(curr_conn);
-      }
-      delete (todelete);
-    } else {
-      prev_conn = curr_conn;
-      curr_conn = curr_conn->getNext();
-    }
-  }
 }
 
 /* the packet will be freed by the calling code */
@@ -156,26 +145,24 @@ Connection *findConnectionWithMatchingSource(Packet *packet,
                                              short int packettype) {
   assert(packet->Outgoing());
 
-  ConnList *current = NULL;
+  ConnList *connList = NULL;
   switch (packettype) {
   case IPPROTO_TCP: {
-    current = connections;
+    connList = &connections;
     break;
   }
 
   case IPPROTO_UDP: {
-    current = unknownudp->connections;
+    connList = &unknownudp->connections;
     break;
   }
   }
 
-  while (current != NULL) {
+  Packet p = packet->onlySource();
+  auto it = connList->lower_bound(&p);
   /* the reference packet is always outgoing */
-    if (packet->matchSource(current->getVal()->refpacket)) {
+  if (it != connList->end() && packet->matchSource((*it)->refpacket)) {
-      return current->getVal();
+    return *it;
-    }
-
-    current = current->getNext();
   }
 
   return NULL;
@@ -184,25 +171,23 @@ Connection *findConnectionWithMatchingSource(Packet *packet,
 Connection *findConnectionWithMatchingRefpacketOrSource(Packet *packet,
                                                         short int packettype) {
 
-  ConnList *current = NULL;
+  ConnList *connList = NULL;
   switch (packettype) {
   case IPPROTO_TCP: {
-    current = connections;
+    connList = &connections;
     break;
   }
 
   case IPPROTO_UDP: {
-    current = unknownudp->connections;
+    connList = &unknownudp->connections;
     break;
   }
   }
 
-  while (current != NULL) {
+  auto it = connList->lower_bound(packet);
   /* the reference packet is always *outgoing* */
-    if (packet->match(current->getVal()->refpacket)) {
+  if (it != connList->end() && packet->match((*it)->refpacket)) {
-      return current->getVal();
+    return *it;
-    }
-    current = current->getNext();
   }
 
   return findConnectionWithMatchingSource(packet, packettype);

src/cui.cpp

@@ -332,13 +332,10 @@ void show_trace(Line *lines[], int nproc) {
   }
 
   /* print the 'unknown' connections, for debugging */
-  ConnList *curr_unknownconn = unknowntcp->connections;
+  for (auto it = unknowntcp->connections.begin(); it != unknowntcp->connections.end(); ++it) {
-  while (curr_unknownconn != NULL) {
     std::cout << "Unknown connection: "
-              << curr_unknownconn->getVal()->refpacket->gethashstring()
+              << (*it)->refpacket->gethashstring()
               << std::endl;
-
-    curr_unknownconn = curr_unknownconn->getNext();
   }
 }
 

src/packet.cpp

@@ -289,7 +289,7 @@ char *Packet::gethashstring() {
 
 /* 2 packets match if they have the same
  * source and destination ports and IP's. */
-bool Packet::match(Packet *other) {
+bool Packet::match(const Packet *other) const {
   return sa_family == other->sa_family && (sport == other->sport) &&
          (dport == other->dport) &&
          (sa_family == AF_INET
@@ -298,9 +298,46 @@ bool Packet::match(Packet *other) {
                     (samein6addr(dip6, other->dip6)));
 }
 
-bool Packet::matchSource(Packet *other) {
+bool Packet::matchSource(const Packet *other) const {
   return sa_family == other->sa_family && (sport == other->sport) &&
          (sa_family == AF_INET
               ? (sameinaddr(sip, other->sip))
               : (samein6addr(sip6, other->sip6)));
 }
+
+Packet Packet::onlySource() const {
+  Packet p = *this;
+  std::fill(std::begin(p.dip6.s6_addr), std::end(p.dip6.s6_addr), 0);
+  p.dip.s_addr = 0;
+  p.dport = 0;
+  return p;
+}
+
+bool Packet::operator< (const Packet& other) const {
+  if (sa_family != other.sa_family)
+    return dir < other.sa_family;
+  /* source address first */
+  if (sport != other.sport)
+    return sport < other.sport;
+  if (sa_family == AF_INET) {
+    if (sip.s_addr != other.sip.s_addr)
+      return sip.s_addr < other.sip.s_addr;
+  } else {
+    for (int i = 0; i < 16; i++)
+      if (sip6.s6_addr[i] != other.sip6.s6_addr[i])
+        return sip6.s6_addr[i] < other.sip6.s6_addr[i];
+  }
+  /* destination address second */
+  if (dport != other.dport)
+    return dport < other.dport;
+  if (sa_family == AF_INET) {
+    if (dip.s_addr != other.dip.s_addr)
+      return dip.s_addr < other.dip.s_addr;
+  } else {
+    for (int i = 0; i < 16; i++)
+      if (dip6.s6_addr[i] != other.dip6.s6_addr[i])
+        return dip6.s6_addr[i] < other.dip6.s6_addr[i];
+  }
+  /* equal */
+  return false;
+}

src/packet.h

@@ -70,8 +70,11 @@ public:
   /* is this packet coming from the local host? */
   bool Outgoing();
 
-  bool match(Packet *other);
+  bool match(const Packet *other) const;
-  bool matchSource(Packet *other);
+  bool matchSource(const Packet *other) const;
+  /* returns a copy with destination information stripped (for comparisons) */
+  Packet onlySource() const;
+  bool operator< (const Packet& other) const;
   /* returns '1.2.3.4:5-1.2.3.4:6'-style string */
   char *gethashstring();
 

src/process.cpp

@@ -97,13 +97,10 @@ void process_init() {
 
 int Process::getLastPacket() {
   int lastpacket = 0;
-  ConnList *curconn = connections;
+  for (auto it = connections.begin(); it != connections.end(); ++it) {
-  while (curconn != NULL) {
+    assert(*it != NULL);
-    assert(curconn != NULL);
+    if ((*it)->getLastPacket() > lastpacket)
-    assert(curconn->getVal() != NULL);
+      lastpacket = (*it)->getLastPacket();
-    if (curconn->getVal()->getLastPacket() > lastpacket)
-      lastpacket = curconn->getVal()->getLastPacket();
-    curconn = curconn->getNext();
   }
   return lastpacket;
 }
@@ -113,30 +110,20 @@ static void sum_active_connections(Process *process_ptr, u_int64_t &sum_sent,
                                    u_int64_t &sum_recv) {
   /* walk though all process_ptr process's connections, and sum
    * them up */
-  ConnList *curconn = process_ptr->connections;
+  for (auto it = process_ptr->connections.begin(); it != process_ptr->connections.end(); ) {
-  ConnList *previous = NULL;
+    if ((*it)->getLastPacket() <= curtime.tv_sec - CONNTIMEOUT) {
-  while (curconn != NULL) {
-    if (curconn->getVal()->getLastPacket() <= curtime.tv_sec - CONNTIMEOUT) {
       /* capture sent and received totals before deleting */
-      process_ptr->sent_by_closed_bytes += curconn->getVal()->sumSent;
+      process_ptr->sent_by_closed_bytes += (*it)->sumSent;
-      process_ptr->rcvd_by_closed_bytes += curconn->getVal()->sumRecv;
+      process_ptr->rcvd_by_closed_bytes += (*it)->sumRecv;
       /* stalled connection, remove. */
-      ConnList *todelete = curconn;
+      delete (*it);
-      Connection *conn_todelete = curconn->getVal();
+      it = process_ptr->connections.erase(it);
-      curconn = curconn->getNext();
-      if (todelete == process_ptr->connections)
-        process_ptr->connections = curconn;
-      if (previous != NULL)
-        previous->setNext(curconn);
-      delete (todelete);
-      delete (conn_todelete);
     } else {
       u_int64_t sent = 0, recv = 0;
-      curconn->getVal()->sumanddel(curtime, &recv, &sent);
+      (*it)->sumanddel(curtime, &recv, &sent);
       sum_sent += sent;
       sum_recv += recv;
-      previous = curconn;
+      ++it;
-      curconn = curconn->getNext();
     }
   }
 }
@@ -171,12 +158,10 @@ void Process::getgbps(float *recvd, float *sent) {
 /** get total values for this process */
 void Process::gettotal(u_int64_t *recvd, u_int64_t *sent) {
   u_int64_t sum_sent = 0, sum_recv = 0;
-  ConnList *curconn = this->connections;
+  for (auto it = this->connections.begin(); it != this->connections.end(); ++it) {
-  while (curconn != NULL) {
+    Connection *conn = (*it);
-    Connection *conn = curconn->getVal();
     sum_sent += conn->sumSent;
     sum_recv += conn->sumRecv;
-    curconn = curconn->getNext();
   }
   // std::cout << "Sum sent: " << sum_sent << std::endl;
   // std::cout << "Sum recv: " << sum_recv << std::endl;
@@ -403,7 +388,7 @@ Process *getProcess(Connection *connection, const char *devicename,
     processes = new ProcList(proc, processes);
   }
 
-  proc->connections = new ConnList(connection, proc->connections);
+  proc->connections.insert(connection);
   return proc;
 }
 

src/process.h

@@ -26,32 +26,30 @@
 #include "connection.h"
 #include "nethogs.h"
 #include <cassert>
+#include <set>
 
 extern bool tracemode;
 extern bool bughuntmode;
 
 void check_all_procs();
 
-class ConnList {
+/* compares Connection pointers by their refpacket */
-public:
+struct ConnectionComparator {
-  ConnList(Connection *m_val, ConnList *m_next) {
+  using is_transparent = void;
-    assert(m_val != NULL);
+  bool operator()(const Connection* l, const Connection* r) const {
-    val = m_val;
+    return *l->refpacket < *r->refpacket;
-    next = m_next;
   }
-  ~ConnList() {
+  bool operator()(const Packet* l, const Connection* r) const {
-    /* does not delete its value, to allow a connection to
+    return *l < *r->refpacket;
-     * remove itself from the global connlist in its destructor */
+  }
+  bool operator()(const Connection* l, const Packet* r) const {
+    return *l->refpacket < *r;
   }
-  Connection *getVal() { return val; }
-  void setNext(ConnList *m_next) { next = m_next; }
-  ConnList *getNext() { return next; }
-
-private:
-  Connection *val;
-  ConnList *next;
 };
 
+/* ordered set of Connection pointers */
+typedef std::multiset<Connection*, ConnectionComparator> ConnList;
+
 class Process {
 public:
   /* the process makes a copy of the name. the device name needs to be stable.
@@ -75,7 +73,6 @@ public:
       cmdline = strdup(m_cmdline);
 
     devicename = m_devicename;
-    connections = NULL;
     pid = 0;
     uid = 0;
     sent_by_closed_bytes = 0;
@@ -106,7 +103,7 @@ public:
   u_int64_t sent_by_closed_bytes;
   u_int64_t rcvd_by_closed_bytes;
 
-  ConnList *connections;
+  ConnList connections;
   uid_t getUid() { return uid; }
 
   void setUid(uid_t m_uid) { uid = m_uid; }