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+/***************************************************************************
+ * engine_epoll.c -- epoll(7) 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).
+ *
+ ***************************************************************************/
+
+/* $Id$ */
+
+#ifdef HAVE_CONFIG_H
+#include "nsock_config.h"
+#endif
+
+#if HAVE_EPOLL
+
+#include <sys/epoll.h>
+#include <errno.h>
+
+#include "nsock_internal.h"
+#include "nsock_log.h"
+
+#if HAVE_PCAP
+#include "nsock_pcap.h"
+#endif
+
+#define INITIAL_EV_COUNT 128
+
+#define EPOLL_R_FLAGS (EPOLLIN | EPOLLPRI)
+#define EPOLL_W_FLAGS EPOLLOUT
+
+/* EPOLLRDHUP was introduced later and might be unavailable on older systems. */
+#ifndef EPOLLRDHUP
+ #define EPOLLRDHUP 0
+#endif
+#define EPOLL_X_FLAGS (EPOLLERR | EPOLLRDHUP| EPOLLHUP)
+
+
+/* --- ENGINE INTERFACE PROTOTYPES --- */
+static int epoll_init(struct npool *nsp);
+static void epoll_destroy(struct npool *nsp);
+static int epoll_iod_register(struct npool *nsp, struct niod *iod, struct nevent *nse, int ev);
+static int epoll_iod_unregister(struct npool *nsp, struct niod *iod);
+static int epoll_iod_modify(struct npool *nsp, struct niod *iod, struct nevent *nse, int ev_set, int ev_clr);
+static int epoll_loop(struct npool *nsp, int msec_timeout);
+
+extern struct io_operations posix_io_operations;
+
+/* ---- ENGINE DEFINITION ---- */
+struct io_engine engine_epoll = {
+ "epoll",
+ epoll_init,
+ epoll_destroy,
+ epoll_iod_register,
+ epoll_iod_unregister,
+ epoll_iod_modify,
+ epoll_loop,
+ &posix_io_operations
+};
+
+
+/* --- INTERNAL PROTOTYPES --- */
+static void iterate_through_event_lists(struct npool *nsp, int evcount);
+
+/* 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;
+
+
+/*
+ * Engine specific data structure
+ */
+struct epoll_engine_info {
+ /* file descriptor corresponding to our epoll instance */
+ int epfd;
+ /* number of epoll_events we can deal with */
+ int evlen;
+ /* list of epoll events, resized if necessary (when polling over large numbers of IODs) */
+ struct epoll_event *events;
+};
+
+
+int epoll_init(struct npool *nsp) {
+ struct epoll_engine_info *einfo;
+
+ einfo = (struct epoll_engine_info *)safe_malloc(sizeof(struct epoll_engine_info));
+
+ einfo->epfd = epoll_create(10); /* argument is ignored */
+ einfo->evlen = INITIAL_EV_COUNT;
+ einfo->events = (struct epoll_event *)safe_malloc(einfo->evlen * sizeof(struct epoll_event));
+
+ nsp->engine_data = (void *)einfo;
+
+ return 1;
+}
+
+void epoll_destroy(struct npool *nsp) {
+ struct epoll_engine_info *einfo = (struct epoll_engine_info *)nsp->engine_data;
+
+ assert(einfo != NULL);
+ close(einfo->epfd);
+ free(einfo->events);
+ free(einfo);
+}
+
+int epoll_iod_register(struct npool *nsp, struct niod *iod, struct nevent *nse, int ev) {
+ int sd;
+ struct epoll_event epev;
+ struct epoll_engine_info *einfo = (struct epoll_engine_info *)nsp->engine_data;
+
+ assert(!IOD_PROPGET(iod, IOD_REGISTERED));
+
+ iod->watched_events = ev;
+
+ memset(&epev, 0x00, sizeof(struct epoll_event));
+ epev.events = EPOLLET;
+ epev.data.ptr = (void *)iod;
+
+ if (ev & EV_READ)
+ epev.events |= EPOLL_R_FLAGS;
+ if (ev & EV_WRITE)
+ epev.events |= EPOLL_W_FLAGS;
+
+ sd = nsock_iod_get_sd(iod);
+ if (epoll_ctl(einfo->epfd, EPOLL_CTL_ADD, sd, &epev) < 0)
+ fatal("Unable to register IOD #%lu: %s", iod->id, strerror(errno));
+
+ IOD_PROPSET(iod, IOD_REGISTERED);
+ return 1;
+}
+
+int epoll_iod_unregister(struct npool *nsp, struct niod *iod) {
+ iod->watched_events = EV_NONE;
+
+ /* some IODs can be unregistered here if they're associated to an event that was
+ * immediately completed */
+ if (IOD_PROPGET(iod, IOD_REGISTERED)) {
+ struct epoll_engine_info *einfo = (struct epoll_engine_info *)nsp->engine_data;
+ int sd;
+
+ sd = nsock_iod_get_sd(iod);
+ epoll_ctl(einfo->epfd, EPOLL_CTL_DEL, sd, NULL);
+
+ IOD_PROPCLR(iod, IOD_REGISTERED);
+ }
+ return 1;
+}
+
+int epoll_iod_modify(struct npool *nsp, struct niod *iod, struct nevent *nse, int ev_set, int ev_clr) {
+ int sd;
+ struct epoll_event epev;
+ int new_events;
+ struct epoll_engine_info *einfo = (struct epoll_engine_info *)nsp->engine_data;
+
+ assert((ev_set & ev_clr) == 0);
+ assert(IOD_PROPGET(iod, IOD_REGISTERED));
+
+ memset(&epev, 0x00, sizeof(struct epoll_event));
+ epev.events = EPOLLET;
+ epev.data.ptr = (void *)iod;
+
+ new_events = iod->watched_events;
+ new_events |= ev_set;
+ new_events &= ~ev_clr;
+
+ if (new_events == iod->watched_events)
+ return 1; /* nothing to do */
+
+ iod->watched_events = new_events;
+
+ /* regenerate the current set of events for this IOD */
+ if (iod->watched_events & EV_READ)
+ epev.events |= EPOLL_R_FLAGS;
+ if (iod->watched_events & EV_WRITE)
+ epev.events |= EPOLL_W_FLAGS;
+
+ sd = nsock_iod_get_sd(iod);
+
+ if (epoll_ctl(einfo->epfd, EPOLL_CTL_MOD, sd, &epev) < 0)
+ fatal("Unable to update events for IOD #%lu: %s", iod->id, strerror(errno));
+
+ return 1;
+}
+
+int epoll_loop(struct npool *nsp, int msec_timeout) {
+ int results_left = 0;
+ int event_msecs; /* msecs before an event goes off */
+ int combined_msecs;
+ int sock_err = 0;
+ unsigned int iod_count;
+ struct epoll_engine_info *einfo = (struct epoll_engine_info *)nsp->engine_data;
+
+ assert(msec_timeout >= -1);
+
+ if (nsp->events_pending == 0)
+ return 0; /* No need to wait on 0 events ... */
+
+
+ iod_count = gh_list_count(&nsp->active_iods);
+ if (iod_count > einfo->evlen) {
+ einfo->evlen = iod_count * 2;
+ einfo->events = (struct epoll_event *)safe_realloc(einfo->events, einfo->evlen * sizeof(struct epoll_event));
+ }
+
+ do {
+ struct nevent *nse;
+
+ 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. */
+ } else
+#endif
+#endif
+ {
+ results_left = epoll_wait(einfo->epfd, einfo->events, einfo->evlen, combined_msecs);
+ if (results_left == -1)
+ sock_err = socket_errno();
+ }
+
+ gettimeofday(&nsock_tod, NULL); /* Due to epoll delay */
+ } while (results_left == -1 && sock_err == EINTR); /* repeat only if signal occurred */
+
+ if (results_left == -1 && sock_err != EINTR) {
+ 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, results_left);
+
+ return 1;
+}
+
+
+/* ---- INTERNAL FUNCTIONS ---- */
+static inline int get_evmask(struct epoll_engine_info *einfo, int n) {
+ int evmask = EV_NONE;
+
+ if (einfo->events[n].events & EPOLL_R_FLAGS)
+ evmask |= EV_READ;
+ if (einfo->events[n].events & EPOLL_W_FLAGS)
+ evmask |= EV_WRITE;
+ if (einfo->events[n].events & EPOLL_X_FLAGS)
+ evmask |= EV_EXCEPT;
+
+ return evmask;
+}
+
+/* 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, int evcount) {
+ struct epoll_engine_info *einfo = (struct epoll_engine_info *)nsp->engine_data;
+ int n;
+
+ for (n = 0; n < evcount; n++) {
+ struct niod *nsi = (struct niod *)einfo->events[n].data.ptr;
+
+ assert(nsi);
+
+ /* process all the pending events for this IOD */
+ process_iod_events(nsp, nsi, get_evmask(einfo, n));
+
+ if (nsi->state == NSIOD_STATE_DELETED) {
+ gh_list_remove(&nsp->active_iods, &nsi->nodeq);
+ gh_list_prepend(&nsp->free_iods, &nsi->nodeq);
+ }
+ }
+
+ /* iterate through timers and expired events */
+ process_expired_events(nsp);
+}
+
+#endif /* HAVE_EPOLL */
+
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