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https://agent.ghink.cloud/wb2osz/direwolf
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74ac4812d5
Expanded debug options so you can understand what is going on with packet filtering. Added new document Successful-APRS-IGate-Operation.pdf with IGate background, configuration, and troubleshooting tips.
318 lines
8.3 KiB
C
318 lines
8.3 KiB
C
//
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// This file is part of Dire Wolf, an amateur radio packet TNC.
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//
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// Copyright (C) 2016 John Langner, WB2OSZ
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//
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/*------------------------------------------------------------------
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*
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* Name: cdigipeater.c
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*
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* Purpose: Act as an digital repeater for connected AX.25 mode.
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* Similar digipeater.c is for APRS.
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*
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*
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* Description: Decide whether the specified packet should
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* be digipeated. Put my callsign in the digipeater field used.
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*
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* APRS and connected mode were two split into two
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* separate files. Yes, there is duplicate code but they
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* are significantly different and I thought it would be
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* too confusing to munge them together.
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*
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* References: The Ax.25 protcol barely mentions digipeaters and
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* and doesn't describe how they should work.
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*
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*------------------------------------------------------------------*/
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#define CDIGIPEATER_C
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#include "direwolf.h"
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include <stdio.h>
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#include <ctype.h> /* for isdigit, isupper */
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#include "regex.h"
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#include <sys/unistd.h>
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#include "ax25_pad.h"
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#include "cdigipeater.h"
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#include "textcolor.h"
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#include "tq.h"
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#include "pfilter.h"
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static packet_t cdigipeat_match (int from_chan, packet_t pp, char *mycall_rec, char *mycall_xmit,
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regex_t *alias, int to_chan, char *filter_str);
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/*
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* Keep pointer to configuration options.
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* Set by cdigipeater_init and used later.
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*/
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static struct audio_s *save_audio_config_p;
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static struct cdigi_config_s *save_cdigi_config_p;
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/*
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* Maintain count of packets digipeated for each combination of from/to channel.
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*/
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static int cdigi_count[MAX_CHANS][MAX_CHANS];
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int cdigipeater_get_count (int from_chan, int to_chan) {
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return (cdigi_count[from_chan][to_chan]);
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}
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/*------------------------------------------------------------------------------
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*
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* Name: cdigipeater_init
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*
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* Purpose: Initialize with stuff from configuration file.
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*
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* Inputs: p_audio_config - Configuration for audio channels.
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*
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* p_cdigi_config - Connected Digipeater configuration details.
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*
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* Outputs: Save pointers to configuration for later use.
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*
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* Description: Called once at application startup time.
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*
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*------------------------------------------------------------------------------*/
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void cdigipeater_init (struct audio_s *p_audio_config, struct cdigi_config_s *p_cdigi_config)
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{
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save_audio_config_p = p_audio_config;
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save_cdigi_config_p = p_cdigi_config;
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}
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/*------------------------------------------------------------------------------
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*
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* Name: cdigipeater
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*
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* Purpose: Re-transmit packet if it matches the rules.
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*
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* Inputs: chan - Radio channel where it was received.
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*
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* pp - Packet object.
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*
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* Returns: None.
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*
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*------------------------------------------------------------------------------*/
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void cdigipeater (int from_chan, packet_t pp)
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{
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int to_chan;
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if ( from_chan < 0 || from_chan >= MAX_CHANS || ( ! save_audio_config_p->achan[from_chan].valid) ) {
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text_color_set(DW_COLOR_ERROR);
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dw_printf ("cdigipeater: Did not expect to receive on invalid channel %d.\n", from_chan);
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return;
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}
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/*
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* First pass: Look at packets being digipeated to same channel.
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*
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* There was a reason for two passes for APRS.
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* Might not have a benefit here.
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*/
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for (to_chan=0; to_chan<MAX_CHANS; to_chan++) {
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if (save_cdigi_config_p->enabled[from_chan][to_chan]) {
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if (to_chan == from_chan) {
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packet_t result;
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result = cdigipeat_match (from_chan, pp, save_audio_config_p->achan[from_chan].mycall,
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save_audio_config_p->achan[to_chan].mycall,
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&save_cdigi_config_p->alias[from_chan][to_chan], to_chan,
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save_cdigi_config_p->filter_str[from_chan][to_chan]);
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if (result != NULL) {
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tq_append (to_chan, TQ_PRIO_0_HI, result);
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cdigi_count[from_chan][to_chan]++;
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}
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}
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}
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}
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/*
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* Second pass: Look at packets being digipeated to different channel.
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*/
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for (to_chan=0; to_chan<MAX_CHANS; to_chan++) {
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if (save_cdigi_config_p->enabled[from_chan][to_chan]) {
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if (to_chan != from_chan) {
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packet_t result;
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result = cdigipeat_match (from_chan, pp, save_audio_config_p->achan[from_chan].mycall,
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save_audio_config_p->achan[to_chan].mycall,
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&save_cdigi_config_p->alias[from_chan][to_chan], to_chan,
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save_cdigi_config_p->filter_str[from_chan][to_chan]);
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if (result != NULL) {
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tq_append (to_chan, TQ_PRIO_0_HI, result);
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cdigi_count[from_chan][to_chan]++;
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}
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}
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}
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}
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} /* end cdigipeater */
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/*------------------------------------------------------------------------------
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*
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* Name: cdigipeat_match
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*
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* Purpose: A simple digipeater for connected mode AX.25.
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*
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* Input: pp - Pointer to a packet object.
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*
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* mycall_rec - Call of my station, with optional SSID,
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* associated with the radio channel where the
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* packet was received.
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*
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* mycall_xmit - Call of my station, with optional SSID,
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* associated with the radio channel where the
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* packet is to be transmitted. Could be the same as
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* mycall_rec or different.
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*
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* alias - Compiled pattern for my station aliases.
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* Could be NULL if no aliases.
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*
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* to_chan - Channel number that we are transmitting to.
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*
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* filter_str - Filter expression string or NULL.
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*
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* Returns: Packet object for transmission or NULL.
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* The original packet is not modified. The caller is responsible for freeing it.
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* We make a copy and return that modified copy!
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* This is very important because we could digipeat from one channel to many.
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*
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* Description: The packet will be digipeated if the next unused digipeater
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* field matches one of the following:
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*
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* - mycall_rec
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* - alias list
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*
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* APRS digipeating drops duplicates within 30 seconds but we don't do that here.
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*
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*------------------------------------------------------------------------------*/
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static packet_t cdigipeat_match (int from_chan, packet_t pp, char *mycall_rec, char *mycall_xmit,
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regex_t *alias, int to_chan, char *filter_str)
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{
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int r;
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char repeater[AX25_MAX_ADDR_LEN];
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int err;
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char err_msg[100];
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/*
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* First check if filtering has been configured.
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*/
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if (filter_str != NULL) {
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if (pfilter(from_chan, to_chan, filter_str, pp, 0) != 1) {
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return(NULL);
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}
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}
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/*
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* Find the first repeater station which doesn't have "has been repeated" set.
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*
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* r = index of the address position in the frame.
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*/
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r = ax25_get_first_not_repeated(pp);
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if (r < AX25_REPEATER_1) {
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return (NULL); // Nothing to do.
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}
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ax25_get_addr_with_ssid(pp, r, repeater);
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#if DEBUG
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text_color_set(DW_COLOR_DEBUG);
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dw_printf ("First unused digipeater is %s\n", repeater);
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#endif
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/*
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* First check for explicit use of my call.
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* Note that receive and transmit channels could have different callsigns.
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*/
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if (strcmp(repeater, mycall_rec) == 0) {
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packet_t result;
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result = ax25_dup (pp);
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assert (result != NULL);
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/* If using multiple radio channels, they could have different calls. */
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ax25_set_addr (result, r, mycall_xmit);
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ax25_set_h (result, r);
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return (result);
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}
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/*
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* If we have an alias match, substitute MYCALL.
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*/
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if (alias != NULL) {
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err = regexec(alias,repeater,0,NULL,0);
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if (err == 0) {
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packet_t result;
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result = ax25_dup (pp);
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assert (result != NULL);
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ax25_set_addr (result, r, mycall_xmit);
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ax25_set_h (result, r);
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return (result);
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}
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else if (err != REG_NOMATCH) {
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regerror(err, alias, err_msg, sizeof(err_msg));
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text_color_set (DW_COLOR_ERROR);
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dw_printf ("%s\n", err_msg);
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}
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}
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/*
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* Don't repeat it if we get here.
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*/
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return (NULL);
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} /* end cdigipeat_match */
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/* end cdigipeater.c */
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