Adding upstream version 7.94+git20230807.3be01efb1+dfsg.upstream/7.94+git20230807.3be01efb1+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 788 insertions, 0 deletions

diff --git a/nsock/src/engine_iocp.c b/nsock/src/engine_iocp.c
new file mode 100644
index 0000000..b1d4302
--- /dev/null
+++ b/nsock/src/engine_iocp.c
@@ -0,0 +1,788 @@
+/***************************************************************************
+ * engine_iocp.c -- I/O Completion Ports based IO engine.                  *
+ *                                                                         *
+ ***********************IMPORTANT NSOCK LICENSE TERMS***********************
+ *
+ * The nsock parallel socket event library is (C) 1999-2023 Nmap Software LLC
+ * This library is free software; you may redistribute and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation; Version 2. This guarantees your right to use, modify, and
+ * redistribute this software under certain conditions. If this license is
+ * unacceptable to you, Nmap Software LLC may be willing to sell alternative
+ * licenses (contact sales@nmap.com ).
+ *
+ * As a special exception to the GPL terms, Nmap Software LLC grants permission
+ * to link the code of this program with any version of the OpenSSL library
+ * which is distributed under a license identical to that listed in the included
+ * docs/licenses/OpenSSL.txt file, and distribute linked combinations including
+ * the two. You must obey the GNU GPL in all respects for all of the code used
+ * other than OpenSSL. If you modify this file, you may extend this exception to
+ * your version of the file, but you are not obligated to do so.
+ *
+ * If you received these files with a written license agreement stating terms
+ * other than the (GPL) terms above, then that alternative license agreement
+ * takes precedence over this comment.
+ *
+ * Source is provided to this software because we believe users have a right to
+ * know exactly what a program is going to do before they run it. This also
+ * allows you to audit the software for security holes.
+ *
+ * Source code also allows you to port Nmap to new platforms, fix bugs, and add
+ * new features. You are highly encouraged to send your changes to the
+ * dev@nmap.org mailing list for possible incorporation into the main
+ * distribution. By sending these changes to Fyodor or one of the Insecure.Org
+ * development mailing lists, or checking them into the Nmap source code
+ * repository, it is understood (unless you specify otherwise) that you are
+ * offering the Nmap Project (Nmap Software LLC) the unlimited, non-exclusive
+ * right to reuse, modify, and relicense the code. Nmap will always be available
+ * Open Source, but this is important because the inability to relicense code
+ * has caused devastating problems for other Free Software projects (such as KDE
+ * and NASM). We also occasionally relicense the code to third parties as
+ * discussed above. If you wish to specify special license conditions of your
+ * contributions, just say so when you send them.
+ *
+ * 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 v2.0 for more
+ * details (http://www.gnu.org/licenses/gpl-2.0.html).
+ *
+ ***************************************************************************/
+
+/* $Id$ */
+
+#if WIN32
+#include "nsock_winconfig.h"
+#endif
+
+#if HAVE_IOCP
+
+#include <Winsock2.h>
+#include <Mswsock.h>
+
+#include "nsock_internal.h"
+#include "nsock_log.h"
+
+#if HAVE_PCAP
+#include "nsock_pcap.h"
+#endif
+
+
+/* --- ENGINE INTERFACE PROTOTYPES --- */
+static int iocp_init(struct npool *nsp);
+static void iocp_destroy(struct npool *nsp);
+static int iocp_iod_register(struct npool *nsp, struct niod *iod, struct nevent *nse, int ev);
+static int iocp_iod_unregister(struct npool *nsp, struct niod *iod);
+static int iocp_iod_modify(struct npool *nsp, struct niod *iod, struct nevent *nse, int ev_set, int ev_clr);
+static int iocp_loop(struct npool *nsp, int msec_timeout);
+
+int iocp_iod_connect(struct npool *nsp, int sockfd, const struct sockaddr *addr, socklen_t addrlen);
+int iocp_iod_read(struct npool *nsp, int sockfd, void *buf, size_t len, int flags, struct sockaddr *src_addr, socklen_t *addrlen);
+int iocp_iod_write(struct npool *nsp, int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen);
+
+struct io_operations iocp_io_operations = {
+  iocp_iod_connect,
+  iocp_iod_read,
+  iocp_iod_write
+};
+
+/* ---- ENGINE DEFINITION ---- */
+struct io_engine engine_iocp = {
+  "iocp",
+  iocp_init,
+  iocp_destroy,
+  iocp_iod_register,
+  iocp_iod_unregister,
+  iocp_iod_modify,
+  iocp_loop,
+  &iocp_io_operations
+};
+
+/*
+* Engine specific data structure
+*/
+struct iocp_engine_info {
+  /* The handle to the Completion Port*/
+  HANDLE iocp;
+
+  /* We put the current eov to be processed here in order to be retrieved by nsock_core */
+  struct extended_overlapped *eov;
+
+  /* The overlapped_entry list used to retrieve completed packets from the port */
+  OVERLAPPED_ENTRY *eov_list;
+  unsigned long capacity;
+
+  /* How many Completion Packets we actually retreieved */
+  unsigned long entries_removed;
+
+  gh_list_t active_eovs;
+  gh_list_t free_eovs;
+};
+
+struct extended_overlapped {
+  /* Overlapped structure used for overlapped operations */
+  OVERLAPPED ov;
+
+  /* Did we get an error when we initiated the operation?
+  Put the error code here and post it to the main loop */
+  int err;
+
+  /* The event may have expired and was recycled, we can't trust
+  a pointer to the nevent structure to tell us the real nevent */
+  nsock_event_id nse_id;
+
+  /* A pointer to the event */
+  struct nevent *nse;
+
+  /* Needed for WSARecv/WSASend */
+  WSABUF wsabuf;
+
+  /* This is the buffer we will read data in */
+  char *readbuf;
+
+  /* The struct npool keeps track of EOVs that have been allocated so that it
+  * can destroy them if the msp is deleted.  This pointer makes it easy to
+  * remove this struct extended_overlapped from the allocated list when necessary */
+  gh_lnode_t nodeq;
+};
+
+/* --- INTERNAL PROTOTYPES --- */
+static void iterate_through_event_lists(struct npool *nsp);
+static void iterate_through_pcap_events(struct npool *nsp);
+static void terminate_overlapped_event(struct npool *nsp, struct nevent *nse);
+static void initiate_overlapped_event(struct npool *nsp, struct nevent *nse);
+static int get_overlapped_result(struct npool *nsp, int fd, const void *buffer, size_t count);
+static void force_operation(struct npool *nsp, struct nevent *nse);
+static void free_eov(struct npool *nsp, struct extended_overlapped *eov);
+static int map_faulty_errors(int err);
+
+/* defined in nsock_core.c */
+void process_iod_events(struct npool *nsp, struct niod *nsi, int ev);
+void process_event(struct npool *nsp, gh_list_t *evlist, struct nevent *nse, int ev);
+void process_expired_events(struct npool *nsp);
+#if HAVE_PCAP
+#ifndef PCAP_CAN_DO_SELECT
+int pcap_read_on_nonselect(struct npool *nsp);
+#endif
+#endif
+
+/* defined in nsock_event.c */
+void update_first_events(struct nevent *nse);
+
+
+extern struct timeval nsock_tod;
+
+int iocp_init(struct npool *nsp) {
+  struct iocp_engine_info *iinfo;
+
+  iinfo = (struct iocp_engine_info *)safe_malloc(sizeof(struct iocp_engine_info));
+
+  gh_list_init(&iinfo->active_eovs);
+  gh_list_init(&iinfo->free_eovs);
+
+  iinfo->iocp = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, NULL, 0);
+  iinfo->capacity = 10;
+  iinfo->eov = NULL;
+  iinfo->entries_removed = 0;
+  iinfo->eov_list = (OVERLAPPED_ENTRY *)safe_malloc(iinfo->capacity * sizeof(OVERLAPPED_ENTRY));
+  nsp->engine_data = (void *)iinfo;
+
+  return 1;
+}
+
+void iocp_destroy(struct npool *nsp) {
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+
+  assert(iinfo != NULL);
+
+  struct extended_overlapped *eov;
+  gh_lnode_t *current;
+
+  while ((current = gh_list_pop(&iinfo->active_eovs))) {
+    eov = container_of(current, struct extended_overlapped, nodeq);
+    if (eov->readbuf) {
+      free(eov->readbuf);
+      eov->readbuf = NULL;
+    }
+    free(eov);
+  }
+
+  while ((current = gh_list_pop(&iinfo->free_eovs))) {
+    eov = container_of(current, struct extended_overlapped, nodeq);
+    free(eov);
+  }
+
+  gh_list_free(&iinfo->active_eovs);
+  gh_list_free(&iinfo->free_eovs);
+
+  CloseHandle(iinfo->iocp);
+  free(iinfo->eov_list);
+
+  free(iinfo);
+}
+
+int iocp_iod_register(struct npool *nsp, struct niod *iod, struct nevent *nse, int ev) {
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+  HANDLE result;
+
+  assert(!IOD_PROPGET(iod, IOD_REGISTERED));
+  iod->watched_events = ev;
+  result = CreateIoCompletionPort((HANDLE)iod->sd, iinfo->iocp, NULL, 0);
+  assert(result);
+
+  IOD_PROPSET(iod, IOD_REGISTERED);
+
+  initiate_overlapped_event(nsp, nse);
+
+  return 1;
+}
+
+/* Sadly a socket can't be unassociated with a completion port */
+int iocp_iod_unregister(struct npool *nsp, struct niod *iod) {
+
+  if (IOD_PROPGET(iod, IOD_REGISTERED)) {
+    /* Nuke all uncompleted operations on that iod */
+    CancelIo((HANDLE)iod->sd);
+    IOD_PROPCLR(iod, IOD_REGISTERED);
+  }
+
+  return 1;
+}
+
+int iocp_iod_modify(struct npool *nsp, struct niod *iod, struct nevent *nse, int ev_set, int ev_clr) {
+  int new_events;
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+
+  assert((ev_set & ev_clr) == 0);
+  assert(IOD_PROPGET(iod, IOD_REGISTERED));
+
+  new_events = iod->watched_events;
+  new_events |= ev_set;
+  new_events &= ~ev_clr;
+
+  if (ev_set != EV_NONE)
+    initiate_overlapped_event(nsp, nse);
+  else if (ev_clr != EV_NONE)
+    terminate_overlapped_event(nsp, nse);
+
+  if (new_events == iod->watched_events)
+    return 1; /* nothing to do */
+
+  iod->watched_events = new_events;
+
+  return 1;
+}
+
+int iocp_loop(struct npool *nsp, int msec_timeout) {
+  int event_msecs; /* msecs before an event goes off */
+  int combined_msecs;
+  int sock_err = 0;
+  BOOL bRet;
+  unsigned long total_events;
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+
+  assert(msec_timeout >= -1);
+
+  if (nsp->events_pending == 0)
+    return 0; /* No need to wait on 0 events ... */
+
+
+  struct nevent *nse;
+
+  /* Make sure the preallocated space for the retrieved events is big enough */
+  total_events = gh_list_count(&nsp->connect_events) + gh_list_count(&nsp->read_events) + gh_list_count(&nsp->write_events);
+  if (iinfo->capacity < total_events) {
+    iinfo->capacity *= 2;
+    iinfo->eov_list = (OVERLAPPED_ENTRY *)safe_realloc(iinfo->eov_list, iinfo->capacity * sizeof(OVERLAPPED_ENTRY));
+  }
+
+  nsock_log_debug_all("wait for events");
+
+  nse = next_expirable_event(nsp);
+  if (!nse)
+    event_msecs = -1; /* None of the events specified a timeout */
+  else
+    event_msecs = MAX(0, TIMEVAL_MSEC_SUBTRACT(nse->timeout, nsock_tod));
+
+#if HAVE_PCAP
+#ifndef PCAP_CAN_DO_SELECT
+  /* Force a low timeout when capturing packets on systems where
+  * the pcap descriptor is not select()able. */
+  if (gh_list_count(&nsp->pcap_read_events) > 0)
+  if (event_msecs > PCAP_POLL_INTERVAL)
+    event_msecs = PCAP_POLL_INTERVAL;
+#endif
+#endif
+
+  /* We cast to unsigned because we want -1 to be very high (since it means no
+  * timeout) */
+  combined_msecs = MIN((unsigned)event_msecs, (unsigned)msec_timeout);
+
+#if HAVE_PCAP
+#ifndef PCAP_CAN_DO_SELECT
+  /* do non-blocking read on pcap devices that doesn't support select()
+  * If there is anything read, just leave this loop. */
+  if (pcap_read_on_nonselect(nsp)) {
+    /* okay, something was read. */
+    gettimeofday(&nsock_tod, NULL);
+    iterate_through_pcap_events(nsp);
+  }
+  else
+#endif
+#endif
+  {
+    /* It is mandatory these values are reset before calling GetQueuedCompletionStatusEx */
+    iinfo->entries_removed = 0;
+    memset(iinfo->eov_list, 0, iinfo->capacity * sizeof(OVERLAPPED_ENTRY));
+    bRet = GetQueuedCompletionStatusEx(iinfo->iocp, iinfo->eov_list, iinfo->capacity, &iinfo->entries_removed, combined_msecs, FALSE);
+
+    gettimeofday(&nsock_tod, NULL); /* Due to iocp delay */
+    if (!bRet) {
+      sock_err = socket_errno();
+      if (!iinfo->eov && sock_err != WAIT_TIMEOUT) {
+        nsock_log_error("nsock_loop error %d: %s", sock_err, socket_strerror(sock_err));
+        nsp->errnum = sock_err;
+        return -1;
+      }
+    }
+  }
+
+  iterate_through_event_lists(nsp);
+
+  return 1;
+}
+
+
+/* ---- INTERNAL FUNCTIONS ---- */
+
+#if HAVE_PCAP
+/* Iterate through pcap events separately, since these are not tracked in iocp_engine_info */
+void iterate_through_pcap_events(struct npool *nsp) {
+  gh_lnode_t *current, *next, *last;
+
+  last = gh_list_last_elem(&nsp->active_iods);
+
+  for (current = gh_list_first_elem(&nsp->active_iods);
+       current != NULL && gh_lnode_prev(current) != last;
+       current = next) {
+    struct niod *nsi = container_of(current, struct niod, nodeq);
+
+    if (nsi->pcap && nsi->state != NSIOD_STATE_DELETED && nsi->events_pending)
+    {
+      process_iod_events(nsp, nsi, EV_READ);
+    }
+
+    next = gh_lnode_next(current);
+    if (nsi->state == NSIOD_STATE_DELETED) {
+      gh_list_remove(&nsp->active_iods, current);
+      gh_list_prepend(&nsp->free_iods, current);
+    }
+  }
+}
+#endif
+
+/* Iterate through all the event lists (such as connect_events, read_events,
+* timer_events, etc) and take action for those that have completed (due to
+* timeout, i/o, etc) */
+void iterate_through_event_lists(struct npool *nsp) {
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+
+  for (unsigned long i = 0; i < iinfo->entries_removed; i++) {
+
+    iinfo->eov = (struct extended_overlapped *)iinfo->eov_list[i].lpOverlapped;
+    /* We can't rely on iinfo->entries_removed to tell us the real number of
+     * events to process */
+    if (!iinfo->eov || !iinfo->eov->nse)
+      continue;
+
+    /* We check if this is from a cancelled operation */
+    if (iinfo->eov->nse->id != iinfo->eov->nse_id ||
+        iinfo->eov->nse->event_done) {
+      free_eov(nsp, iinfo->eov);
+      iinfo->eov = NULL;
+      continue;
+    }
+
+    if (!HasOverlappedIoCompleted((OVERLAPPED *)iinfo->eov))
+      continue;
+
+    struct niod *nsi = iinfo->eov->nse->iod;
+    struct nevent *nse = iinfo->eov->nse;
+    gh_list_t *evlist = NULL;
+    int ev = 0;
+
+    switch (nse->type) {
+      case NSE_TYPE_CONNECT:
+      case NSE_TYPE_CONNECT_SSL:
+        ev = EV_READ;
+        evlist = &nsp->connect_events;
+        break;
+      case NSE_TYPE_READ:
+        ev = EV_READ;
+        evlist = &nsp->read_events;
+        break;
+      case NSE_TYPE_WRITE:
+        ev = EV_WRITE;
+        evlist = &nsp->write_events;
+        break;
+    }
+
+    /* Setting the connect error for nsock_core to get in handle_connect_result */
+    if (nse->type == NSE_TYPE_CONNECT || nse->type == NSE_TYPE_CONNECT_SSL) {
+      setsockopt(nse->iod->sd, SOL_SOCKET, SO_UPDATE_CONNECT_CONTEXT, NULL, 0);
+      DWORD dwRes;
+      if (!GetOverlappedResult((HANDLE)nse->iod->sd, (LPOVERLAPPED)iinfo->eov, &dwRes, FALSE)) {

+        int err = map_faulty_errors(socket_errno());
+        if (err)
+          setsockopt(nse->iod->sd, SOL_SOCKET, SO_ERROR, (char *)&err, sizeof(err));
+      }
+    }
+
+    process_event(nsp, evlist, nse, ev);
+
+    if (nse->event_done) {
+      /* event is done, remove it from the event list and update IOD pointers
+      * to the first events of each kind */
+      update_first_events(nse);
+      gh_list_remove(evlist, &nse->nodeq_io);
+      gh_list_append(&nsp->free_events, &nse->nodeq_io);
+
+      if (nse->timeout.tv_sec)
+        gh_heap_remove(&nsp->expirables, &nse->expire);
+    } else
+      initiate_overlapped_event(nsp, nse);
+
+    if (nsi->state == NSIOD_STATE_DELETED) {
+      gh_list_remove(&nsp->active_iods, &nsi->nodeq);
+      gh_list_prepend(&nsp->free_iods, &nsi->nodeq);
+    }
+
+    iinfo->eov = NULL;
+  }
+
+  /* iterate through timers and expired events */
+  process_expired_events(nsp);
+}
+
+static int errcode_is_failure(int err) {
+#ifndef WIN32
+  return err != EINTR && err != EAGAIN && err != EBUSY;
+#else
+  return err != EINTR && err != EAGAIN && err != WSA_IO_PENDING && err != ERROR_NETNAME_DELETED;
+#endif
+}
+
+static int map_faulty_errors(int err) {
+  /* This actually happens https://svn.boost.org/trac/boost/ticket/10744 */
+  switch (err) {
+    case ERROR_NETWORK_UNREACHABLE: return WSAENETUNREACH;
+    case ERROR_HOST_UNREACHABLE: return WSAEHOSTUNREACH;
+    case ERROR_CONNECTION_REFUSED: return WSAECONNREFUSED;
+    case ERROR_SEM_TIMEOUT: return WSAETIMEDOUT;
+  }
+  return err;
+}
+
+static struct extended_overlapped *new_eov(struct npool *nsp, struct nevent *nse) {
+  struct extended_overlapped *eov;
+  gh_lnode_t *lnode;
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+
+  lnode = gh_list_pop(&iinfo->free_eovs);

+  if (!lnode)
+    eov = (struct extended_overlapped *)safe_malloc(sizeof(struct extended_overlapped));
+  else
+    eov = container_of(lnode, struct extended_overlapped, nodeq);
+
+  memset(eov, 0, sizeof(struct extended_overlapped));
+  nse->eov = eov;
+  eov->nse = nse;
+  eov->nse_id = nse->id;
+  eov->err = 0;
+  gh_list_prepend(&iinfo->active_eovs, &eov->nodeq);
+
+  /* Make the read buffer equal to the size of the buffer in do_actual_read() */
+  if (nse->type == NSE_TYPE_READ && !eov->readbuf && !nse->iod->ssl)
+    eov->readbuf = (char*)safe_malloc(READ_BUFFER_SZ * sizeof(char));
+
+  return eov;
+}
+
+/* This needs to be called after getting the overlapped event in */
+static void free_eov(struct npool *nsp, struct extended_overlapped *eov) {
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+  struct nevent *nse = eov->nse;
+
+  gh_list_remove(&iinfo->active_eovs, &eov->nodeq);
+
+  if (eov->readbuf) {
+    free(eov->readbuf);
+    eov->readbuf = NULL;
+  }
+
+  gh_list_prepend(&iinfo->free_eovs, &eov->nodeq);
+
+  eov->nse = NULL;
+  if (nse)
+    nse->eov = NULL;
+}
+
+
+static void call_connect_overlapped(struct npool *nsp, struct nevent *nse) {
+  BOOL ok;
+  DWORD numBytes = 0;
+  int one = 1;
+  SOCKET sock = nse->iod->sd;
+  GUID guid = WSAID_CONNECTEX;
+  struct sockaddr_in addr;
+  LPFN_CONNECTEX ConnectExPtr = NULL;
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nse->iod->nsp->engine_data;
+  struct extended_overlapped *eov = new_eov(nsp, nse);
+  int ret;
+  struct sockaddr_storage *ss = &nse->iod->peer;
+  size_t sslen = nse->iod->peerlen;
+
+  if (nse->iod->lastproto != IPPROTO_TCP) {
+    if (connect(sock, (struct sockaddr *)ss, sslen) == -1) {
+      int err = socket_errno();
+      nse->event_done = 1;
+      nse->status = NSE_STATUS_ERROR;
+      nse->errnum = err;
+    } else {
+      force_operation(nsp, nse);
+    }
+    return;
+  }
+
+  ret = WSAIoctl(sock, SIO_GET_EXTENSION_FUNCTION_POINTER,
+    (void*)&guid, sizeof(guid), (void*)&ConnectExPtr, sizeof(ConnectExPtr),
+    &numBytes, NULL, NULL);
+  if (ret)
+    fatal("Error initiating event type(%d)", nse->type);
+
+  ret = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (const char *)&one, sizeof(one));

+  if (ret == -1) {

+    int err = socket_errno();
+    nse->event_done = 1;
+    nse->status = NSE_STATUS_ERROR;
+    nse->errnum = err;
+    return;
+  }
+
+  /* ConnectEx doesn't automatically bind the socket */
+  memset(&addr, 0, sizeof(addr));
+  addr.sin_family = AF_INET;
+  addr.sin_addr.s_addr = INADDR_ANY;
+  addr.sin_port = 0;
+  if (!nse->iod->locallen) {
+    ret = bind(sock, (SOCKADDR*)&addr, sizeof(addr));
+    if (ret) {
+      int err = socket_errno();
+      nse->event_done = 1;
+      nse->status = NSE_STATUS_ERROR;
+      nse->errnum = err;
+      return;
+    }
+  }
+
+  ok = ConnectExPtr(sock, (SOCKADDR*)ss, sslen, NULL, 0, NULL, (LPOVERLAPPED)eov);
+  if (!ok) {
+    int err = socket_errno();
+    if (err != ERROR_IO_PENDING) {
+      nse->event_done = 1;
+      nse->status = NSE_STATUS_ERROR;
+      nse->errnum = err;
+    }
+  }
+}
+
+static void call_read_overlapped(struct nevent *nse) {
+  DWORD flags = 0;
+  int err = 0;
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nse->iod->nsp->engine_data;
+
+  struct extended_overlapped *eov = new_eov(nse->iod->nsp, nse);
+
+  eov->wsabuf.buf = eov->readbuf;
+  eov->wsabuf.len = READ_BUFFER_SZ;
+
+  err = WSARecvFrom(nse->iod->sd, &eov->wsabuf, 1, NULL, &flags,
+    (struct sockaddr *)&nse->iod->peer, (LPINT)&nse->iod->peerlen, (LPOVERLAPPED)eov, NULL);
+  if (err) {
+    err = socket_errno();
+    if (errcode_is_failure(err)) {
+      // WSARecvFrom with overlapped I/O may generate ERROR_PORT_UNREACHABLE on ICMP error.
+      // We'll translate that so Nsock-using software doesn't have to know about it.
+      eov->err = (err == ERROR_PORT_UNREACHABLE ? ECONNREFUSED : err);
+      /* Send the error to the main loop to be picked up by the appropriate handler */
+      BOOL bRet = PostQueuedCompletionStatus(iinfo->iocp, -1, (ULONG_PTR)nse->iod, (LPOVERLAPPED)eov);
+      if (!bRet)
+        fatal("Error initiating event type(%d)", nse->type);
+    }
+  }
+}
+
+static void call_write_overlapped(struct nevent *nse) {
+  int err;
+  char *str;
+  int bytesleft;
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nse->iod->nsp->engine_data;
+
+  struct extended_overlapped *eov = new_eov(nse->iod->nsp, nse);
+
+  str = fs_str(&nse->iobuf) + nse->writeinfo.written_so_far;
+  bytesleft = fs_length(&nse->iobuf) - nse->writeinfo.written_so_far;
+
+  eov->wsabuf.buf = str;
+  eov->wsabuf.len = bytesleft;
+
+  if (nse->writeinfo.dest.ss_family == AF_UNSPEC)
+    err = WSASend(nse->iod->sd, &eov->wsabuf, 1, NULL, 0, (LPWSAOVERLAPPED)eov, NULL);
+  else
+    err = WSASendTo(nse->iod->sd, &eov->wsabuf, 1, NULL, 0,
+    (struct sockaddr *)&nse->writeinfo.dest, (int)nse->writeinfo.destlen,
+    (LPWSAOVERLAPPED)eov, NULL);
+  if (err) {
+    err = socket_errno();
+    if (errcode_is_failure(err)) {
+      eov->err = err;
+      /* Send the error to the main loop to be picked up by the appropriate handler */
+      BOOL bRet = PostQueuedCompletionStatus(iinfo->iocp, -1, (ULONG_PTR)nse->iod, (LPOVERLAPPED)eov);
+      if (!bRet)
+        fatal("Error initiating event type(%d)", nse->type);
+    }
+  }
+}
+
+/* Anything that isn't an overlapped operation uses this to get processed by the main loop */
+static void force_operation(struct npool *nsp, struct nevent *nse) {
+  BOOL bRet;
+  struct extended_overlapped *eov;
+
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+  eov = new_eov(nse->iod->nsp, nse);
+
+  bRet = PostQueuedCompletionStatus(iinfo->iocp, 0, (ULONG_PTR)nse->iod, (LPOVERLAPPED)eov);
+  if (!bRet)
+    fatal("Error initiating event type(%d)", nse->type);
+}
+
+/* Either initiate a I/O read or force a SSL_read */
+static void initiate_read(struct npool *nsp, struct nevent *nse) {
+  if (!nse->iod->ssl)
+    call_read_overlapped(nse);
+  else
+    force_operation(nsp, nse);
+}
+
+/* Either initiate a I/O write or force a SSL_write */
+static void initiate_write(struct npool *nsp, struct nevent *nse) {
+  if (!nse->iod->ssl)
+    call_write_overlapped(nse);
+  else
+    force_operation(nsp, nse);
+}
+
+/* Force a PCAP read */
+static void initiate_pcap_read(struct npool *nsp, struct nevent *nse) {
+  force_operation(nsp, nse);
+}
+
+static void initiate_connect(struct npool *nsp, struct nevent *nse) {
+  int sslconnect_inprogress = 0;
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+
+#if HAVE_OPENSSL
+  sslconnect_inprogress = nse->type == NSE_TYPE_CONNECT_SSL && nse->iod &&
+    (nse->sslinfo.ssl_desire == SSL_ERROR_WANT_READ ||
+    nse->sslinfo.ssl_desire == SSL_ERROR_WANT_WRITE);
+#endif
+
+  if (sslconnect_inprogress)
+    force_operation(nsp, nse);
+  else
+    call_connect_overlapped(nsp, nse);
+}
+
+/* Start the overlapped I/O operation */
+static void initiate_overlapped_event(struct npool *nsp, struct nevent *nse) {
+  if (nse->eov)
+    terminate_overlapped_event(nsp, nse);
+
+  switch (nse->type) {
+  case NSE_TYPE_CONNECT:
+  case NSE_TYPE_CONNECT_SSL:
+    initiate_connect(nsp, nse);
+    break;
+  case NSE_TYPE_READ:
+    initiate_read(nsp, nse);
+    break;
+  case NSE_TYPE_WRITE:
+    initiate_write(nsp, nse);
+    break;
+#if HAVE_PCAP
+  case NSE_TYPE_PCAP_READ:
+    initiate_pcap_read(nsp, nse);
+    break;
+#endif
+  default: fatal("Event type(%d) not supported by engine IOCP\n", nse->type);
+  }
+}
+
+/* Terminate an overlapped I/O operation that expired */
+static void terminate_overlapped_event(struct npool *nsp, struct nevent *nse) {
+  bool eov_done = true;
+
+  if (nse->eov) {
+    if (!HasOverlappedIoCompleted((LPOVERLAPPED)nse->eov)) {
+      CancelIoEx((HANDLE)nse->iod->sd, (LPOVERLAPPED)nse->eov);
+      eov_done = false;
+    }
+
+    if (eov_done)
+      free_eov(nsp, nse->eov);
+  }
+}
+
+/* Retrieve the amount of bytes transferred or set the appropriate error */
+static int get_overlapped_result(struct npool *nsp, int fd, const void *buffer, size_t count) {
+  char *buf = (char *)buffer;
+  DWORD dwRes = 0;
+  int err;
+  struct iocp_engine_info *iinfo = (struct iocp_engine_info *)nsp->engine_data;
+
+  struct extended_overlapped *eov = iinfo->eov;
+  struct nevent *nse = eov->nse;
+
+  /* If the operation failed at initialization, set the error for nsock_core.c to see */
+  if (eov->err) {
+    SetLastError(map_faulty_errors(eov->err));
+    return -1;
+  }
+
+  if (!GetOverlappedResult((HANDLE)fd, (LPOVERLAPPED)eov, &dwRes, FALSE)) {
+    err = socket_errno();
+    if (errcode_is_failure(err)) {
+      SetLastError(map_faulty_errors(err));
+      return -1;
+    }
+  }
+
+  if (nse->type == NSE_TYPE_READ && buf)
+    memcpy(buf, eov->wsabuf.buf, dwRes);
+
+  return dwRes;
+}
+
+int iocp_iod_connect(struct npool *nsp, int sockfd, const struct sockaddr *addr, socklen_t addrlen) {
+  return 0;
+}
+
+int iocp_iod_read(struct npool *nsp, int sockfd, void *buf, size_t len, int flags, struct sockaddr *src_addr, socklen_t *addrlen) {
+  return get_overlapped_result(nsp, sockfd, buf, len);
+}
+
+int iocp_iod_write(struct npool *nsp, int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen) {
+  return get_overlapped_result(nsp, sockfd, buf, len);
+}
+
+#endif /* HAVE_IOCP */