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pfilter.c
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//
// This file is part of Dire Wolf, an amateur radio packet TNC.
//
// Copyright (C) 2015, 2016 John Langner, WB2OSZ
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// 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 for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
/*------------------------------------------------------------------
*
* Module: pfilter.c
*
* Purpose: Packet filtering based on characteristics.
*
* Description: Sometimes it is desirable to digipeat or drop packets based on rules.
* For example, you might want to pass only weather information thru
* a cross band digipeater or you might want to drop all packets from
* an abusive user that is overloading the channel.
*
* The filter specifications are loosely modeled after the IGate Server-side Filter
* Commands: http://www.aprs-is.net/javaprsfilter.aspx
*
* We add AND, OR, NOT, and ( ) to allow very flexible control.
*
*---------------------------------------------------------------*/
#include "direwolf.h"
#include <unistd.h>
#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include "ax25_pad.h"
#include "textcolor.h"
#include "decode_aprs.h"
#include "latlong.h"
#include "pfilter.h"
#include "mheard.h"
/*
* Global stuff (to this file)
*
* These are set by init function.
*/
static struct igate_config_s *save_igate_config_p;
static int s_debug = 0;
/*-------------------------------------------------------------------
*
* Name: pfilter_init
*
* Purpose: One time initialization when main application starts up.
*
* Inputs: p_igate_config - IGate configuration.
*
* debug_level - 0 no debug output.
* 1 single summary line with final result. Indent by 1.
* 2 details from each filter specification. Indent by 3.
* 3 Logical operators. Indent by 2.
*
*--------------------------------------------------------------------*/
void pfilter_init (struct igate_config_s *p_igate_config, int debug_level)
{
s_debug = debug_level;
save_igate_config_p = p_igate_config;
}
typedef enum token_type_e { TOKEN_AND, TOKEN_OR, TOKEN_NOT, TOKEN_LPAREN, TOKEN_RPAREN, TOKEN_FILTER_SPEC, TOKEN_EOL } token_type_t;
#define MAX_FILTER_LEN 1024
#define MAX_TOKEN_LEN 1024
typedef struct pfstate_s {
int from_chan; /* From and to channels. MAX_CHANS is used for IGate. */
int to_chan; /* Used only for debug and error messages. */
/*
* Original filter string from config file.
* All control characters should be replaced by spaces.
*/
char filter_str[MAX_FILTER_LEN];
int nexti; /* Next available character index. */
/*
* Packet object.
*/
packet_t pp;
/*
* Are we processing APRS or connected mode?
* This determines which types of filters are available.
*/
int is_aprs;
/*
* Packet split into separate parts if APRS.
* Most interesting fields are:
*
* g_symbol_table - / \ or overlay
* g_symbol_code
* g_lat, g_lon - Location
* g_name - for object or item
* g_comment
*/
decode_aprs_t decoded;
/*
* These are set by next_token.
*/
token_type_t token_type;
char token_str[MAX_TOKEN_LEN]; /* Printable string representation for use in error messages. */
int tokeni; /* Index in original string for enhanced error messages. */
} pfstate_t;
static int parse_expr (pfstate_t *pf);
static int parse_or_expr (pfstate_t *pf);
static int parse_and_expr (pfstate_t *pf);
static int parse_primary (pfstate_t *pf);
static int parse_filter_spec (pfstate_t *pf);
static void next_token (pfstate_t *pf);
static void print_error (pfstate_t *pf, char *msg);
static int filt_bodgu (pfstate_t *pf, char *pattern);
static int filt_t (pfstate_t *pf);
static int filt_r (pfstate_t *pf, char *sdist);
static int filt_s (pfstate_t *pf);
static int filt_i (pfstate_t *pf);
static char *bool2text (int val)
{
if (val == 1) return "TRUE";
if (val == 0) return "FALSE";
if (val == -1) return "ERROR";
return "OOPS!";
}
/*-------------------------------------------------------------------
*
* Name: pfilter.c
*
* Purpose: Decide whether a packet should be allowed thru.
*
* Inputs: from_chan - Channel packet is coming from.
* to_chan - Channel packet is going to.
* Both are 0 .. MAX_CHANS-1 or MAX_CHANS for IGate.
* For debug/error messages only.
*
* filter - String of filter specs and logical operators to combine them.
*
* pp - Packet object handle.
*
* is_aprs - True for APRS, false for connected mode digipeater.
* Connected mode allows a subset of the filter types, only
* looking at the addresses, not information part contents.
*
* Returns: 1 = yes
* 0 = no
* -1 = error detected
*
* Description: This might be running in multiple threads at the same time so
* no static data allowed and take other thread-safe precautions.
*
*--------------------------------------------------------------------*/
int pfilter (int from_chan, int to_chan, char *filter, packet_t pp, int is_aprs)
{
pfstate_t pfstate;
char *p;
int result;
char * infop = NULL;
assert (from_chan >= 0 && from_chan <= MAX_CHANS);
assert (to_chan >= 0 && to_chan <= MAX_CHANS);
memset (&pfstate, 0, sizeof(pfstate));
if (pp == NULL) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("INTERNAL ERROR in pfilter: NULL packet pointer. Please report this!\n");
return (-1);
}
if (filter == NULL) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("INTERNAL ERROR in pfilter: NULL filter string pointer. Please report this!\n");
return (-1);
}
pfstate.from_chan = from_chan;
pfstate.to_chan = to_chan;
/* Copy filter string, changing any control characters to spaces. */
strlcpy (pfstate.filter_str, filter, sizeof(pfstate.filter_str));
pfstate.nexti = 0;
for (p = pfstate.filter_str; *p != '\0'; p++) {
if (iscntrl(*p)) {
*p = ' ';
}
}
(void) ax25_get_info (pp, (unsigned char **)(&infop));
assert (infop != NULL);
if (*infop == '}') {
// We have a 3d party packet, dig inside it to get the actual type.
packet_t pp_payload = ax25_from_text ((char*)infop+1, 0);
if (pp_payload == NULL) {
print_error (&pfstate, "Invalid third party payload\n");
return (0);
}
return pfilter(from_chan, to_chan, filter, pp_payload, is_aprs);
}
pfstate.pp = pp;
pfstate.is_aprs = is_aprs;
if (is_aprs) {
decode_aprs (&pfstate.decoded, pp, 1, 0);
}
next_token(&pfstate);
if (pfstate.token_type == TOKEN_EOL) {
/* Empty filter means reject all. */
result = 0;
}
else {
result = parse_expr (&pfstate);
if (pfstate.token_type != TOKEN_AND &&
pfstate.token_type != TOKEN_OR &&
pfstate.token_type != TOKEN_EOL) {
print_error (&pfstate, "Expected logical operator or end of line here.");
result = -1;
}
}
if (s_debug >= 1) {
text_color_set(DW_COLOR_DEBUG);
if (from_chan == MAX_CHANS) {
dw_printf (" Packet filter from IGate to radio channel %d returns %s\n", to_chan, bool2text(result));
}
else if (to_chan == MAX_CHANS) {
dw_printf (" Packet filter from radio channel %d to IGate returns %s\n", from_chan, bool2text(result));
}
else if (is_aprs) {
dw_printf (" Packet filter for APRS digipeater from radio channel %d to %d returns %s\n", from_chan, to_chan, bool2text(result));
}
else {
dw_printf (" Packet filter for traditional digipeater from radio channel %d to %d returns %s\n", from_chan, to_chan, bool2text(result));
}
}
return (result);
} /* end pfilter */
/*-------------------------------------------------------------------
*
* Name: next_token
*
* Purpose: Extract the next token from input string.
*
* Inputs: pf - Pointer to current state information.
*
* Outputs: See definition of the structure.
*
* Description: Look for these special operators: & | ! ( ) end-of-line
* Anything else is considered a filter specification.
* Note that a filter-spec must be followed by space or
* end of line. This is so the magic characters can appear in one.
*
* Future: Maybe allow words like 'OR' as alternatives to symbols like '|'.
*
* Unresolved Issue:
*
* Adding the special operators adds a new complication.
* How do we handle the case where we want those characters in
* a filter specification? For example how do we know if the
* last character of /#& means HF gateway or AND the next part
* of the expression.
*
* Approach 1: Require white space after all filter specifications.
* Currently implemented.
* Simple. Easy to explain.
* More readable than having everything squashed together.
*
* Approach 2: Use escape character to get literal value. e.g. s/#\&
* Linux people would be comfortable with this but
* others might have a problem with it.
*
* Approach 3: use quotation marks if it contains special characters or space.
* "s/#&" Simple. Allows embedded space but I'm not sure
* that's useful. Doesn't hurt to always put the quotes there
* if you can't remember which characters are special.
*
*--------------------------------------------------------------------*/
static void next_token (pfstate_t *pf)
{
while (pf->filter_str[pf->nexti] == ' ') {
pf->nexti++;
}
pf->tokeni = pf->nexti;
if (pf->filter_str[pf->nexti] == '\0') {
pf->token_type = TOKEN_EOL;
strlcpy (pf->token_str, "end-of-line", sizeof(pf->token_str));
}
else if (pf->filter_str[pf->nexti] == '&') {
pf->nexti++;
pf->token_type = TOKEN_AND;
strlcpy (pf->token_str, "\"&\"", sizeof(pf->token_str));
}
else if (pf->filter_str[pf->nexti] == '|') {
pf->nexti++;
pf->token_type = TOKEN_OR;
strlcpy (pf->token_str, "\"|\"", sizeof(pf->token_str));
}
else if (pf->filter_str[pf->nexti] == '!') {
pf->nexti++;
pf->token_type = TOKEN_NOT;
strlcpy (pf->token_str, "\"!\"", sizeof(pf->token_str));
}
else if (pf->filter_str[pf->nexti] == '(') {
pf->nexti++;
pf->token_type = TOKEN_LPAREN;
strlcpy (pf->token_str, "\"(\"", sizeof(pf->token_str));
}
else if (pf->filter_str[pf->nexti] == ')') {
pf->nexti++;
pf->token_type = TOKEN_RPAREN;
strlcpy (pf->token_str, "\")\"", sizeof(pf->token_str));
}
else {
char *p = pf->token_str;
pf->token_type = TOKEN_FILTER_SPEC;
do {
*p++ = pf->filter_str[pf->nexti++];
} while (pf->filter_str[pf->nexti] != ' ' && pf->filter_str[pf->nexti] != '\0');
*p = '\0';
}
} /* end next_token */
/*-------------------------------------------------------------------
*
* Name: parse_expr
* parse_or_expr
* parse_and_expr
* parse_primary
*
* Purpose: Recursive descent parser to evaluate filter specifications
* contained within expressions with & | ! ( ).
*
* Inputs: pf - Pointer to current state information.
*
* Returns: 1 = yes
* 0 = no
* -1 = error detected
*
*--------------------------------------------------------------------*/
static int parse_expr (pfstate_t *pf)
{
int result;
result = parse_or_expr (pf);
return (result);
}
/* or_expr:: and_expr [ | and_expr ] ... */
static int parse_or_expr (pfstate_t *pf)
{
int result;
result = parse_and_expr (pf);
if (result < 0) return (-1);
while (pf->token_type == TOKEN_OR) {
int e;
next_token (pf);
e = parse_and_expr (pf);
if (s_debug >= 3) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s | %s\n", bool2text(result), bool2text(e));
}
if (e < 0) return (-1);
result |= e;
}
return (result);
}
/* and_expr:: primary [ & primary ] ... */
static int parse_and_expr (pfstate_t *pf)
{
int result;
result = parse_primary (pf);
if (result < 0) return (-1);
while (pf->token_type == TOKEN_AND) {
int e;
next_token (pf);
e = parse_primary (pf);
if (s_debug >= 3) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s & %s\n", bool2text(result), bool2text(e));
}
if (e < 0) return (-1);
result &= e;
}
return (result);
}
/* primary:: ( expr ) */
/* ! primary */
/* filter_spec */
static int parse_primary (pfstate_t *pf)
{
int result;
if (pf->token_type == TOKEN_LPAREN) {
next_token (pf);
result = parse_expr (pf);
if (pf->token_type == TOKEN_RPAREN) {
next_token (pf);
}
else {
print_error (pf, "Expected \")\" here.\n");
result = -1;
}
}
else if (pf->token_type == TOKEN_NOT) {
int e;
next_token (pf);
e = parse_primary (pf);
if (s_debug >= 3) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" ! %s\n", bool2text(e));
}
if (e < 0) result = -1;
else result = ! e;
}
else if (pf->token_type == TOKEN_FILTER_SPEC) {
result = parse_filter_spec (pf);
}
else {
print_error (pf, "Expected filter specification, (, or ! here.");
result = -1;
}
return (result);
}
/*-------------------------------------------------------------------
*
* Name: parse_filter_spec
*
* Purpose: Parse and evaluate filter specification.
*
* Inputs: pf - Pointer to current state information.
*
* Returns: 1 = yes
* 0 = no
* -1 = error detected
*
* Description: All filter specifications are allowed for APRS.
* Only those dealing with addresses are allowed for connected digipeater.
*
* b - budlist (source)
* d - digipeaters used
* v - digipeaters not used
* u - unproto (destination)
*
*--------------------------------------------------------------------*/
static int parse_filter_spec (pfstate_t *pf)
{
int result = -1;
if ( ( ! pf->is_aprs) && strchr ("01bdvu", pf->token_str[0]) == NULL) {
print_error (pf, "Only b, d, v, and u specifications are allowed for connected mode digipeater filtering.");
result = -1;
next_token (pf);
return (result);
}
/* undocumented: can use 0 or 1 for testing. */
if (strcmp(pf->token_str, "0") == 0) {
result = 0;
}
else if (strcmp(pf->token_str, "1") == 0) {
result = 1;
}
/* simple string matching */
/* b - budlist */
else if (pf->token_str[0] == 'b' && ispunct(pf->token_str[1])) {
/* Budlist - source address */
char addr[AX25_MAX_ADDR_LEN];
ax25_get_addr_with_ssid (pf->pp, AX25_SOURCE, addr);
result = filt_bodgu (pf, addr);
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %s\n", pf->token_str, bool2text(result), addr);
}
}
/* o - object or item name */
else if (pf->token_str[0] == 'o' && ispunct(pf->token_str[1])) {
result = filt_bodgu (pf, pf->decoded.g_name);
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %s\n", pf->token_str, bool2text(result), pf->decoded.g_name);
}
}
/* d - was digipeated by */
else if (pf->token_str[0] == 'd' && ispunct(pf->token_str[1])) {
int n;
// loop on all digipeaters
result = 0;
for (n = AX25_REPEATER_1; result == 0 && n < ax25_get_num_addr (pf->pp); n++) {
// Consider only those with the H (has-been-used) bit set.
if (ax25_get_h (pf->pp, n)) {
char addr[AX25_MAX_ADDR_LEN];
ax25_get_addr_with_ssid (pf->pp, n, addr);
result = filt_bodgu (pf, addr);
}
}
if (s_debug >= 2) {
char path[100];
ax25_format_via_path (pf->pp, path, sizeof(path));
if (strlen(path) == 0) {
strcpy (path, "no digipeater path");
}
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %s\n", pf->token_str, bool2text(result), path);
}
}
/* v - via not used */
else if (pf->token_str[0] == 'v' && ispunct(pf->token_str[1])) {
int n;
// loop on all digipeaters (mnemonic Via)
result = 0;
for (n = AX25_REPEATER_1; result == 0 && n < ax25_get_num_addr (pf->pp); n++) {
// This is different than the previous "d" filter.
// Consider only those where the the H (has-been-used) bit is NOT set.
if ( ! ax25_get_h (pf->pp, n)) {
char addr[AX25_MAX_ADDR_LEN];
ax25_get_addr_with_ssid (pf->pp, n, addr);
result = filt_bodgu (pf, addr);
}
}
if (s_debug >= 2) {
char path[100];
ax25_format_via_path (pf->pp, path, sizeof(path));
if (strlen(path) == 0) {
strcpy (path, "no digipeater path");
}
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %s\n", pf->token_str, bool2text(result), path);
}
}
/* g - Addressee of message. */
else if (pf->token_str[0] == 'g' && ispunct(pf->token_str[1])) {
if (ax25_get_dti(pf->pp) == ':') {
result = filt_bodgu (pf, pf->decoded.g_addressee);
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %s\n", pf->token_str, bool2text(result), pf->decoded.g_addressee);
}
}
else {
result = 0;
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %s\n", pf->token_str, bool2text(result), "not a message");
}
}
}
/* u - unproto (destination) */
else if (pf->token_str[0] == 'u' && ispunct(pf->token_str[1])) {
/* Probably want to exclude mic-e types */
/* because destination is used for part of location. */
if (ax25_get_dti(pf->pp) != '\'' && ax25_get_dti(pf->pp) != '`') {
char addr[AX25_MAX_ADDR_LEN];
ax25_get_addr_with_ssid (pf->pp, AX25_DESTINATION, addr);
result = filt_bodgu (pf, addr);
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %s\n", pf->token_str, bool2text(result), addr);
}
}
else {
result = 0;
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %s\n", pf->token_str, bool2text(result), "MIC-E packet type");
}
}
}
/* t - type: position, weather, etc. */
else if (pf->token_str[0] == 't' && ispunct(pf->token_str[1])) {
result = filt_t (pf);
if (s_debug >= 2) {
char *infop = NULL;
(void) ax25_get_info (pf->pp, (unsigned char **)(&infop));
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %c data type indicator\n", pf->token_str, bool2text(result), *infop);
}
}
/* r - range */
else if (pf->token_str[0] == 'r' && ispunct(pf->token_str[1])) {
/* range */
char sdist[30];
strcpy (sdist, "unknown distance");
result = filt_r (pf, sdist);
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dw_printf (" %s returns %s for %s\n", pf->token_str, bool2text(result), sdist);
}
}
/* s - symbol */
else if (pf->token_str[0] == 's' && ispunct(pf->token_str[1])) {
/* symbol */
result = filt_s (pf);
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
if (pf->decoded.g_symbol_table == '/') {
dw_printf (" %s returns %s for symbol %c in primary table\n", pf->token_str, bool2text(result), pf->decoded.g_symbol_code);
}
else if (pf->decoded.g_symbol_table == '\\') {
dw_printf (" %s returns %s for symbol %c in alternate table\n", pf->token_str, bool2text(result), pf->decoded.g_symbol_code);
}
else {
dw_printf (" %s returns %s for symbol %c with overlay %c\n", pf->token_str, bool2text(result), pf->decoded.g_symbol_code, pf->decoded.g_symbol_table);
}
}
}
/* i - IGate messaging default */
else if (pf->token_str[0] == 'i' && ispunct(pf->token_str[1])) {
/* IGatge messaging */
result = filt_i (pf);
if (s_debug >= 2) {
char *infop = NULL;
(void) ax25_get_info (pf->pp, (unsigned char **)(&infop));
text_color_set(DW_COLOR_DEBUG);
if (*infop == ':' && ! is_telem_metadata(infop)) {
dw_printf (" %s returns %s for message to %s\n", pf->token_str, bool2text(result), pf->decoded.g_addressee);
}
else {
dw_printf (" %s returns %s for not an APRS 'message'\n", pf->token_str, bool2text(result));
}
}
}
/* unrecognized filter type */
else {
char stemp[80];
snprintf (stemp, sizeof(stemp), "Unrecognized filter type '%c'", pf->token_str[0]);
print_error (pf, stemp);
result = -1;
}
next_token (pf);
return (result);
}
/*------------------------------------------------------------------------------
*
* Name: filt_bodgu
*
* Purpose: Filter with text pattern matching
*
* Inputs: pf - Pointer to current state information.
* token_str should have one of these filter specs:
*
* Budlist b/call1/call2...
* Object o/obj1/obj2...
* Digipeater d/digi1/digi2...
* Group Msg g/call1/call2...
* Unproto u/unproto1/unproto2...
* Via-not-yet v/digi1/digi2...noteapd
*
* arg - Value to match from source addr, destination,
* used digipeater, object name, etc.
*
* Returns: 1 = yes
* 0 = no
* -1 = error detected
*
* Description: Same function is used for all of these because they are so similar.
* Look for exact match to any of the specified strings.
* All of them allow wildcarding with single * at the end.
*
*------------------------------------------------------------------------------*/
static int filt_bodgu (pfstate_t *pf, char *arg)
{
char str[MAX_TOKEN_LEN];
char *cp;
char sep[2];
char *v;
int result = 0;
strlcpy (str, pf->token_str, sizeof(str));
sep[0] = str[1];
sep[1] = '\0';
cp = str + 2;
while (result == 0 && (v = strsep (&cp, sep)) != NULL) {
int mlen;
char *w;
if ((w = strchr(v,'*')) != NULL) {
/* Wildcarding. Should have single * on end. */
mlen = w - v;
if (mlen != (int)(strlen(v) - 1)) {
print_error (pf, "Any wildcard * must be at the end of pattern.\n");
return (-1);
}
if (strncmp(v,arg,mlen) == 0) result = 1;
}
else {
/* Try for exact match. */
if (strcmp(v,arg) == 0) result = 1;
}
}
return (result);
}
/*------------------------------------------------------------------------------
*
* Name: filt_t
*
* Purpose: Filter by packet type.
*
* Inputs: pf - Pointer to current state information.
*
* Returns: 1 = yes
* 0 = no
* -1 = error detected
*
* Description: The filter is based the type filtering described here:
* http://www.aprs-is.net/javAPRSFilter.aspx
*
* Most of these simply check the first byte of the information part.
* Trying to detect NWS information is a little trickier.
* http://www.aprs-is.net/WX/
* http://wxsvr.aprs.net.au/protocol-new.html
*
*------------------------------------------------------------------------------*/
/* Telemetry metadata is a special case of message. */
/* We want to categorize it as telemetry rather than message. */
int is_telem_metadata (char *infop)
{
if (*infop != ':') return (0);
if (strlen(infop) < 16) return (0);
if (strncmp(infop+10, ":PARM.", 6) == 0) return (1);
if (strncmp(infop+10, ":UNIT.", 6) == 0) return (1);
if (strncmp(infop+10, ":EQNS.", 6) == 0) return (1);
if (strncmp(infop+10, ":BITS.", 6) == 0) return (1);
return (0);
}
static int filt_t (pfstate_t *pf)
{
char src[AX25_MAX_ADDR_LEN];
char *infop = NULL;
char *f;
memset (src, 0, sizeof(src));
ax25_get_addr_with_ssid (pf->pp, AX25_SOURCE, src);
(void) ax25_get_info (pf->pp, (unsigned char **)(&infop));
assert (infop != NULL);
for (f = pf->token_str + 2; *f != '\0'; f++) {
switch (*f) {
case 'p': /* Position */
if (*infop == '!') return (1);
if (*infop == '/') return (1);
if (*infop == '=') return (1);
if (*infop == '@') return (1);
if (*infop == '\'') return (1); // MIC-E
if (*infop == '`') return (1); // MIC-E
// What if we have "_" symbol code for weather?
// Still consider as position.
// The same packet can match more than one type here.
break;
case 'o': /* Object */
if (*infop == ';') return (1);
break;
case 'i': /* Item */
if (*infop == ')') return (1);
break;
case 'm': /* Message */
if (*infop == ':' && ! is_telem_metadata(infop)) return (1);
break;
case 'q': /* Query */
if (*infop == '?') return (1);
break;
case 'c': /* station Capabilities - my extension */
/* Most often used for IGate statistics. */
if (*infop == '<') return (1);
break;
case 's': /* Status */
if (*infop == '>') return (1);
break;
case 't': /* Telemetry */
if (*infop == 'T') return (1);
if (is_telem_metadata(infop)) return (1);
break;
case 'u': /* User-defined */
if (*infop == '{') return (1);
break;
case 'h': /* third party Header - my extension */
if (*infop == '}') return (1);
break;
case 'w': /* Weather */
if (*infop == '*') return (1); // Peet Bros
if (*infop == '_') return (1); // Weather report, no position.
if (strncmp(infop, "!!", 2) == 0) return(1); // Ultimeter 2000.
/* '$' is normally raw GPS. Check for special case. */
if (strncmp(infop, "$ULTW", 5) == 0) return (1);
/* Positions !=/@ with symbol code _ are weather. */
if (strchr("!=/@", *infop) != NULL &&
pf->decoded.g_symbol_code == '_') return (1);
/* Object with _ symbol is also weather. APRS protocol spec page 66. */
if (*infop == ';' &&
pf->decoded.g_symbol_code == '_') return (1);
// TODO: need more test cases at end for new weather cases.
break;
case 'n': /* NWS format */
/*
* This is the interesting case.
* The source must be exactly 6 upper case letters, no SSID.
*/
if (strlen(src) != 6) break;
if (! isupper(src[0])) break;
if (! isupper(src[1])) break;
if (! isupper(src[2])) break;
if (! isupper(src[3])) break;
if (! isupper(src[4])) break;
if (! isupper(src[5])) break;
/*
* We can have a "message" with addressee starting with NWS, SKY, or BOM (Australian version.)
*/
if (strncmp(infop, ":NWS", 4) == 0) return (1);
if (strncmp(infop, ":SKY", 4) == 0) return (1);
if (strncmp(infop, ":BOM", 4) == 0) return (1);
/*
* Or we can have an object.
* It's not exactly clear how to distinguish this from other objects.
* It looks like the first 3 characters of the source should be the same
* as the first 3 characters of the addressee.
*/
if (infop[0] == ';' &&
infop[1] == src[0] &&
infop[2] == src[1] &&
infop[3] == src[2]) return (1);
break;
default:
print_error (pf, "Invalid letter in t/ filter.\n");
return (-1);
break;
}