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- /*
- This file is part of GNUnet.
- Copyright (C) 2009, 2010, 2011, 2016 GNUnet e.V.
- GNUnet is free software: you can redistribute it and/or modify it
- under the terms of the GNU Affero General Public License as published
- by the Free Software Foundation, either version 3 of the License,
- or (at your option) any later version.
- GNUnet 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
- Affero General Public License for more details.
-
- You should have received a copy of the GNU Affero General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>.
- SPDX-License-Identifier: AGPL3.0-or-later
- */
- /**
- * @file nat/gnunet-service-nat_helper.c
- * @brief runs the gnunet-helper-nat-server
- * @author Milan Bouchet-Valat
- * @author Christian Grothoff
- */
- #include "platform.h"
- #include "gnunet_util_lib.h"
- #include "gnunet-service-nat_helper.h"
- /**
- * Information we keep per NAT helper process.
- */
- struct HelperContext
- {
- /**
- * IP address we pass to the NAT helper.
- */
- struct in_addr internal_address;
- /**
- * Function to call if we receive a reversal request.
- */
- GN_ReversalCallback cb;
- /**
- * Closure for @e cb.
- */
- void *cb_cls;
- /**
- * How long do we wait for restarting a crashed gnunet-helper-nat-server?
- */
- struct GNUNET_TIME_Relative server_retry_delay;
- /**
- * ID of select gnunet-helper-nat-server stdout read task
- */
- struct GNUNET_SCHEDULER_Task *server_read_task;
- /**
- * The process id of the server process (if behind NAT)
- */
- struct GNUNET_OS_Process *server_proc;
- /**
- * stdout pipe handle for the gnunet-helper-nat-server process
- */
- struct GNUNET_DISK_PipeHandle *server_stdout;
- /**
- * stdout file handle (for reading) for the gnunet-helper-nat-server process
- */
- const struct GNUNET_DISK_FileHandle *server_stdout_handle;
- };
- /**
- * Task that restarts the gnunet-helper-nat-server process after a crash
- * after a certain delay.
- *
- * @param cls a `struct HelperContext`
- */
- static void
- restart_nat_server (void *cls);
- /**
- * Try again starting the helper later
- *
- * @param h context of the helper
- */
- static void
- try_again (struct HelperContext *h)
- {
- GNUNET_assert (NULL == h->server_read_task);
- h->server_retry_delay
- = GNUNET_TIME_STD_BACKOFF (h->server_retry_delay);
- h->server_read_task
- = GNUNET_SCHEDULER_add_delayed (h->server_retry_delay,
- &restart_nat_server,
- h);
- }
- /**
- * We have been notified that gnunet-helper-nat-server has written
- * something to stdout. Handle the output, then reschedule this
- * function to be called again once more is available.
- *
- * @param cls the `struct HelperContext`
- */
- static void
- nat_server_read (void *cls)
- {
- struct HelperContext *h = cls;
- char mybuf[40];
- ssize_t bytes;
- int port;
- const char *port_start;
- struct sockaddr_in sin_addr;
- h->server_read_task = NULL;
- memset (mybuf,
- 0,
- sizeof (mybuf));
- bytes
- = GNUNET_DISK_file_read (h->server_stdout_handle,
- mybuf,
- sizeof (mybuf));
- if (bytes < 1)
- {
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "Finished reading from server stdout with code: %d\n",
- (int) bytes);
- if (0 != GNUNET_OS_process_kill (h->server_proc,
- GNUNET_TERM_SIG))
- GNUNET_log_from_strerror (GNUNET_ERROR_TYPE_WARNING,
- "nat",
- "kill");
- GNUNET_OS_process_wait (h->server_proc);
- GNUNET_OS_process_destroy (h->server_proc);
- h->server_proc = NULL;
- GNUNET_DISK_pipe_close (h->server_stdout);
- h->server_stdout = NULL;
- h->server_stdout_handle = NULL;
- try_again (h);
- return;
- }
- port_start = NULL;
- for (size_t i = 0; i < sizeof (mybuf); i++)
- {
- if (mybuf[i] == '\n')
- {
- mybuf[i] = '\0';
- break;
- }
- if ((mybuf[i] == ':') && (i + 1 < sizeof (mybuf)))
- {
- mybuf[i] = '\0';
- port_start = &mybuf[i + 1];
- }
- }
- /* construct socket address of sender */
- memset (&sin_addr,
- 0,
- sizeof (sin_addr));
- sin_addr.sin_family = AF_INET;
- #if HAVE_SOCKADDR_IN_SIN_LEN
- sin_addr.sin_len = sizeof (sin_addr);
- #endif
- if ( (NULL == port_start) ||
- (1 != SSCANF (port_start,
- "%d",
- &port)) ||
- (-1 == inet_pton (AF_INET,
- mybuf,
- &sin_addr.sin_addr)))
- {
- /* should we restart gnunet-helper-nat-server? */
- GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
- _("gnunet-helper-nat-server generated malformed address `%s'\n"),
- mybuf);
- h->server_read_task
- = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
- h->server_stdout_handle,
- &nat_server_read,
- h);
- return;
- }
- sin_addr.sin_port = htons ((uint16_t) port);
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "gnunet-helper-nat-server read: %s:%d\n",
- mybuf,
- port);
- h->cb (h->cb_cls,
- &sin_addr);
- h->server_read_task
- = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
- h->server_stdout_handle,
- &nat_server_read,
- h);
- }
- /**
- * Task that restarts the gnunet-helper-nat-server process after a crash
- * after a certain delay.
- *
- * @param cls a `struct HelperContext`
- */
- static void
- restart_nat_server (void *cls)
- {
- struct HelperContext *h = cls;
- char *binary;
- char ia[INET_ADDRSTRLEN];
- h->server_read_task = NULL;
- GNUNET_assert (NULL !=
- inet_ntop (AF_INET,
- &h->internal_address,
- ia,
- sizeof (ia)));
- /* Start the server process */
- binary
- = GNUNET_OS_get_libexec_binary_path ("gnunet-helper-nat-server");
- if (GNUNET_YES !=
- GNUNET_OS_check_helper_binary (binary,
- GNUNET_YES,
- ia))
- {
- /* move instantly to max delay, as this is unlikely to be fixed */
- h->server_retry_delay
- = GNUNET_TIME_STD_EXPONENTIAL_BACKOFF_THRESHOLD;
- GNUNET_free (binary);
- try_again (h);
- return;
- }
- h->server_stdout
- = GNUNET_DISK_pipe (GNUNET_YES, GNUNET_YES,
- GNUNET_NO, GNUNET_YES);
- if (NULL == h->server_stdout)
- {
- GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR,
- "pipe");
- GNUNET_free (binary);
- try_again (h);
- return;
- }
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "Starting `%s' at `%s'\n",
- "gnunet-helper-nat-server",
- ia);
- h->server_proc
- = GNUNET_OS_start_process (GNUNET_NO,
- 0,
- NULL,
- h->server_stdout,
- NULL,
- binary,
- "gnunet-helper-nat-server",
- ia,
- NULL);
- GNUNET_free (binary);
- if (NULL == h->server_proc)
- {
- GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
- _("Failed to start %s\n"),
- "gnunet-helper-nat-server");
- GNUNET_DISK_pipe_close (h->server_stdout);
- h->server_stdout = NULL;
- try_again (h);
- return;
- }
- /* Close the write end of the read pipe */
- GNUNET_DISK_pipe_close_end (h->server_stdout,
- GNUNET_DISK_PIPE_END_WRITE);
- h->server_stdout_handle
- = GNUNET_DISK_pipe_handle (h->server_stdout,
- GNUNET_DISK_PIPE_END_READ);
- h->server_read_task
- = GNUNET_SCHEDULER_add_read_file (GNUNET_TIME_UNIT_FOREVER_REL,
- h->server_stdout_handle,
- &nat_server_read,
- h);
- }
- /**
- * Start the gnunet-helper-nat-server and process incoming
- * requests.
- *
- * @param internal_address
- * @param cb function to call if we receive a request
- * @param cb_cls closure for @a cb
- * @return NULL on error
- */
- struct HelperContext *
- GN_start_gnunet_nat_server_ (const struct in_addr *internal_address,
- GN_ReversalCallback cb,
- void *cb_cls)
- {
- struct HelperContext *h;
- h = GNUNET_new (struct HelperContext);
- h->cb = cb;
- h->cb_cls = cb_cls;
- h->internal_address = *internal_address;
- restart_nat_server (h);
- if (NULL == h->server_stdout)
- {
- GN_stop_gnunet_nat_server_ (h);
- return NULL;
- }
- return h;
- }
- /**
- * Start the gnunet-helper-nat-server and process incoming
- * requests.
- *
- * @param h helper context to stop
- */
- void
- GN_stop_gnunet_nat_server_ (struct HelperContext *h)
- {
- if (NULL != h->server_read_task)
- {
- GNUNET_SCHEDULER_cancel (h->server_read_task);
- h->server_read_task = NULL;
- }
- if (NULL != h->server_proc)
- {
- if (0 != GNUNET_OS_process_kill (h->server_proc,
- GNUNET_TERM_SIG))
- GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,
- "kill");
- GNUNET_OS_process_wait (h->server_proc);
- GNUNET_OS_process_destroy (h->server_proc);
- h->server_proc = NULL;
- GNUNET_DISK_pipe_close (h->server_stdout);
- h->server_stdout = NULL;
- h->server_stdout_handle = NULL;
- }
- if (NULL != h->server_stdout)
- {
- GNUNET_DISK_pipe_close (h->server_stdout);
- h->server_stdout = NULL;
- h->server_stdout_handle = NULL;
- }
- GNUNET_free (h);
- }
- /**
- * We want to connect to a peer that is behind NAT. Run the
- * gnunet-helper-nat-client to send dummy ICMP responses to cause
- * that peer to connect to us (connection reversal).
- *
- * @param internal_address out internal address to use
- * @param internal_port port to use
- * @param remote_v4 the address of the peer (IPv4-only)
- * @return #GNUNET_SYSERR on error,
- * #GNUNET_OK otherwise
- */
- int
- GN_request_connection_reversal (const struct in_addr *internal_address,
- uint16_t internal_port,
- const struct in_addr *remote_v4)
- {
- char intv4[INET_ADDRSTRLEN];
- char remv4[INET_ADDRSTRLEN];
- char port_as_string[6];
- struct GNUNET_OS_Process *proc;
- char *binary;
- if (NULL == inet_ntop (AF_INET,
- internal_address,
- intv4,
- INET_ADDRSTRLEN))
- {
- GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,
- "inet_ntop");
- return GNUNET_SYSERR;
- }
- if (NULL == inet_ntop (AF_INET,
- remote_v4,
- remv4,
- INET_ADDRSTRLEN))
- {
- GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,
- "inet_ntop");
- return GNUNET_SYSERR;
- }
- GNUNET_snprintf (port_as_string,
- sizeof (port_as_string),
- "%d",
- internal_port);
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "Running gnunet-helper-nat-client %s %s %u\n",
- intv4,
- remv4,
- internal_port);
- binary
- = GNUNET_OS_get_libexec_binary_path ("gnunet-helper-nat-client");
- proc
- = GNUNET_OS_start_process (GNUNET_NO,
- 0,
- NULL,
- NULL,
- NULL,
- binary,
- "gnunet-helper-nat-client",
- intv4,
- remv4,
- port_as_string,
- NULL);
- GNUNET_free (binary);
- if (NULL == proc)
- return GNUNET_SYSERR;
- /* we know that the gnunet-helper-nat-client will terminate virtually
- * instantly */
- GNUNET_OS_process_wait (proc);
- GNUNET_OS_process_destroy (proc);
- return GNUNET_OK;
- }
- /* end of gnunet-service-nat_helper.c */
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