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res_digitmap: Support suffixing prefixing extensions.
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Some devices (e.g. Polycom) require that digit map
entries end with a 'T' if the phone should wait
for more digits, rather than complete immediately
when matching that. Not all devices require this,
since many (most?) are smart enough to check all
matches. However, some require the T explicitly
to avoid matching immediately even if other patterns
could match later.

To support this, a "TimeoutSuffix" option has
been added to both the CLI and AMI commands
to suffix patterns that are a proper prefix of
another pattern with the 'T' character. The
implementation here may add false positives,
but it avoids false negatives.
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@InterLinked1
InterLinked1 committed Dec 2, 2023
1 parent 0545b48 commit ec73239
Showing 1 changed file with 115 additions and 10 deletions.
125 changes: 115 additions & 10 deletions res/res_digitmap.c
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Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,7 @@ struct map_geninfo {
};

/*! \retval -1 on failure, number of bytes written on success */
static int generate_digit_map(const char *prefix, const char *context, struct map_geninfo *geninfo, const char *includes[], char *buf, size_t len)
static int generate_digit_map(const char *prefix, const char *rootcontext, const char *context, struct map_geninfo *geninfo, const char *includes[], char *buf, size_t len, int timeoutsuffix)
{
int idx;
struct ast_context *c;
Expand All @@ -106,6 +106,8 @@ static int generate_digit_map(const char *prefix, const char *context, struct ma
while ((e = ast_walk_context_extensions(c, e))) {
char firstchar[2] = "";
int ignorepat = 0;
int needtimeout = 0;
int complex_exten = 0;
const char *startbuf, *name = ast_get_extension_name(e);
/* XXX use macro for this */
if (!strcmp(name, "a") || !strcmp(name, "i") || !strcmp(name, "s") || !strcmp(name, "t")) {
Expand Down Expand Up @@ -155,10 +157,13 @@ static int generate_digit_map(const char *prefix, const char *context, struct ma
/* Digit maps don't understand N or Z, so expand them */
if (*name == 'N') {
buf_append(buf, len, "[2-9]");
complex_exten = 1;
} else if (*name == 'Z') {
buf_append(buf, len, "[1-9]");
complex_exten = 1;
} else if (*name == 'X') {
buf_append(buf, len, "x"); /* Digit maps do recognize 'x', but they use lowercase x, not uppercase X */
complex_exten = 1;
} else if (*name == '!') {
#if 0
/* S0 is not support by Grandstream. So we should just ignore ! characters. */
Expand All @@ -171,6 +176,7 @@ static int generate_digit_map(const char *prefix, const char *context, struct ma
const char *initial_range_start, *range_start, *range_end = strchr(name, ']');

initial_range_start = range_start = name;
complex_exten = 1;
if (!range_end) {
ast_log(LOG_WARNING, "Dialplan is invalid: unterminated range: %s\n", ast_get_extension_name(e));
res = -1;
Expand Down Expand Up @@ -233,6 +239,100 @@ static int generate_digit_map(const char *prefix, const char *context, struct ma
}
name++;
}
#define VALID_DIGIT(x) (isdigit(x) || (x >= 'A' && x <= 'D') || x == '*' || x == '#')
#define VALID_DIGITMAP_DIGIT(x) (VALID_DIGIT(x) || x == 'x')
/* If this is a prefix of another valid extension, certain devices (e.g. Polycom) require the digit T be suffixed. */
if (timeoutsuffix && !needtimeout) {
/* This first check only works for literal extensions, not patterns. */
if (!complex_exten && ast_matchmore_extension(NULL, ast_get_context_name(c), ast_get_extension_name(e), 1, NULL)) {
needtimeout = 1;
} else if (complex_exten) { /* Assume it's a pattenr */
char sample_exten[AST_MAX_EXTENSION + 1]; /* Should ensure bounds check is okay */
char *dst = sample_exten;
int in_pattern = 0;
char start_digit = 0, end_digit = 0;
const char *src = startbuf;
/* If we have a pattern like _[2-9] and the pattern, say, _[2-4]XXX
* then the first pattern is a prefix of the second one (at least when the first digit is 2-4).
* Ideally, we would split the first pattern into _[2-4]T and _[5-9],
* but it would be difficult to do this efficiently, so we compromise
* by allowing for some false positives for timeouts (since false negatives are never acceptable,
* as that would preclude being able to dial certain extensions).
* To do this, we need to instantiate the pattern and see if it could match anything further.
* Admittedly, the way we do this here is not 100% accurate, more probalistic, but should work in most real world use cases: */
while (*src) {
if (*src == '[') {
if (in_pattern++) {
ast_log(LOG_WARNING, "Was already in a pattern match?\n");
}
} else if (*src == ']') {
if (in_pattern--) {
if (!start_digit || !end_digit) {
ast_log(LOG_WARNING, "Pattern missing start or end?\n");
} else {
*dst++ = start_digit;
}
} else {
ast_log(LOG_WARNING, "Wasn't already in a pattern match?\n");
}
} else {
if (in_pattern) {
if (!start_digit) {
if (VALID_DIGIT(*src)) {
start_digit = *src;
} else {
ast_log(LOG_WARNING, "Invalid digit prior to - character: %c\n", *src);
}
} else {
/* Even if the range is not continuous, this is fine for a hueristic approach: */
end_digit = *src;
}
} else {
if (*src != ',') {
if (!VALID_DIGITMAP_DIGIT(*src)) {
ast_log(LOG_WARNING, "Invalid digit outside of pattern match: %c\n", *src);
}
*dst++ = *src;
}
}
}
src++;
}
*dst = '\0';
/* Now, instantiate any instances of X, N, or Z, arbitrarily. */
dst = sample_exten;
while (*dst) {
int min = 0; /* Max is 9 for all */
if (isalpha(*dst)) {
switch (*dst) {
case 'N':
min = 2;
break;
case 'Z':
min = 1;
break;
case 'X':
break;
default:
break;
}
*dst = min + '0'; /* Replace pattern digit with something concrete */
}
dst++;
}
ast_debug(3, "Instantiated pattern '%s' as %s@%s\n", startbuf, sample_exten, rootcontext);
/* It could match in a context that includes the current one, so use the root context for comparison.
* When doing this, we need to include the prefix. */
if (ast_matchmore_extension(NULL, rootcontext, sample_exten, 1, NULL)) {
needtimeout = 1;
}
}
}

if (needtimeout) {
ast_debug(2, "Extension %s %s prefixes other valid extension(s)\n", ast_get_extension_name(e), complex_exten ? "probably" : "definitely");
buf_append(buf, len, "%c", 'T');
}
ast_debug(3, "%p: Added to digit map: %s\n", startbuf, startbuf);
}

Expand Down Expand Up @@ -288,7 +388,7 @@ static int generate_digit_map(const char *prefix, const char *context, struct ma
char newprefix[32];
snprintf(newprefix, sizeof(newprefix), "%s%s", prefix, tmp2); /* prefix is non NULL so no need for S_OR */

res = generate_digit_map(newprefix, includename, geninfo, includes, buf, len);
res = generate_digit_map(newprefix, rootcontext, includename, geninfo, includes, buf, len, timeoutsuffix);

if (res > 0) {
buf += res;
Expand All @@ -313,7 +413,7 @@ static int generate_digit_map(const char *prefix, const char *context, struct ma
return res < 0 ? res : (buf - start);
}

static int generate_digit_map_all(int fd, const char *context_name)
static int generate_digit_map_all(int fd, const char *context_name, int timeoutsuffix)
{
int res = 0;
const char *includes[AST_PBX_MAX_STACK];
Expand All @@ -322,7 +422,7 @@ static int generate_digit_map_all(int fd, const char *context_name)
.includecount = 0,
};

res = generate_digit_map(NULL, context_name, &geninfo, includes, buf, sizeof(buf));
res = generate_digit_map(NULL, context_name, context_name, &geninfo, includes, buf, sizeof(buf), timeoutsuffix);

if (res <= 0) {
return res;
Expand All @@ -342,8 +442,9 @@ static char *handle_dialplan_generate_digitmap(struct ast_cli_entry *e, int cmd,
case CLI_INIT:
e->command = "dialplan generate digitmap";
e->usage =
"Usage: dialplan generate digitmap <context>\n"
" Generate device digit maps for a dialplan context\n";
"Usage: dialplan generate digitmap <context> [T]\n"
" Generate device digit maps for a dialplan context\n"
" The argument T will suffix a T for any extensions that prefix other valid extensions.\n";
return NULL;
case CLI_GENERATE:
#if 0
Expand All @@ -354,36 +455,40 @@ static char *handle_dialplan_generate_digitmap(struct ast_cli_entry *e, int cmd,
#endif
}

if (a->argc != 4) {
if (a->argc != 4 && a->argc != 5) {
return CLI_SHOWUSAGE;
}

return generate_digit_map_all(a->fd, a->argv[3]) ? CLI_FAILURE : CLI_SUCCESS;
return generate_digit_map_all(a->fd, a->argv[3], a->argc == 5) ? CLI_FAILURE : CLI_SUCCESS;
}

static int manager_digitmap(struct mansession *s, const struct message *m)
{
int res = 0;
int timeoutsuffix;
const char *includes[AST_PBX_MAX_STACK];
char buf[BUF_SIZE];
struct map_geninfo geninfo = {
.includecount = 0,
};
const char *id = astman_get_header(m, "ActionID");
const char *context = astman_get_header(m, "Context");
const char *timeoutsuffix_s = astman_get_header(m, "TimeoutSuffix");

if (ast_strlen_zero(context)) {
astman_send_error(s, m, "No context specified");
return 0;
}

res = generate_digit_map(NULL, context, &geninfo, includes, buf, sizeof(buf));
timeoutsuffix = !ast_strlen_zero(timeoutsuffix_s) && ast_true(timeoutsuffix_s);

res = generate_digit_map(NULL, context, context, &geninfo, includes, buf, sizeof(buf), timeoutsuffix);
if (res <= 0) {
astman_send_error(s, m, "Could not generate digit map for requested context");
return 0;
}

ast_debug(1, "Generated digit map length: %d\n", res);
ast_debug(1, "Generated digit map length: %d: '%s'\n", res, buf + 1);
astman_append(s, "Response: Success\r\n");
if (!ast_strlen_zero(id)) {
astman_append(s, "ActionID: %s\r\n", id);
Expand Down

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