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/* media_params.c
* Routines for parsing media type parameters as per RFC 822 and RFC 2045
* Copyright 2004, Anders Broman.
* Copyright 2004, Olivier Biot.
*
* Refer to the AUTHORS file or the AUTHORS section in the man page
* for contacting the author(s) of this file.
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <string.h>
#include <glib.h>
#include <epan/media_params.h>
static const char *
ws_get_next_media_type_parameter(const char *pos, gsize *retnamelen,
const char **retvalue, gsize *retvaluelen,
const char **nextp)
{
const char *p, *namep, *valuep;
char c;
p = pos;
while ((c = *p) != '\0' && g_ascii_isspace(c))
p++; /* Skip white space */
if (c == '\0') {
/* No more parameters left */
return NULL;
}
namep = p;
/* Look for a '\0' (end of string), '=' (end of parameter name,
beginning of parameter value), or ';' (end of parameter). */
while ((c = *p) != '\0' && c != '=' && c != ';')
p++;
*retnamelen = (gsize) (p - namep);
if (c == '\0') {
/* End of string, so end of parameter, no parameter value */
if (retvalue != NULL)
*retvalue = NULL;
if (retvaluelen != NULL)
*retvaluelen = 0;
*nextp = p;
return namep;
}
if (c == ';') {
/* End of parameter, no parameter value */
if (retvalue != NULL)
*retvalue = NULL;
if (retvaluelen != NULL)
*retvaluelen = 0;
*nextp = p + 1;
return namep;
}
/* The parameter has a value. Skip the '=' */
p++;
valuep = p;
if (retvalue != NULL)
*retvalue = valuep;
/* Is the value a quoted string? */
if (*p == '"') {
/* Yes. Skip the opening quote, and scan forward looking for
a non-escaped closing quote. */
p++;
for (;;) {
c = *p;
if (c == '\0') {
/* End-of-string. We're done.
(XXX - this is an error.) */
if (retvaluelen != NULL) {
*retvaluelen = (gsize) (p - valuep);
}
*nextp = p;
return namep;
}
if (c == '"') {
/* Closing quote. Skip it; we're done with
the quoted-string. */
p++;
break;
}
if (c == '\\') {
/* Backslash; this escapes the next character
(quoted-pair). Skip the backslash, and make
sure there *is* a next character. */
p++;
if (*p == '\0') {
/* Nothing left; we're done.
(XXX - this is an error.) */
break;
}
}
/* Skip the character we just processed. */
p++;
}
/* Now scan forward looking for a '\0' (end of string)
or ';' (end of parameter), in case there's any
extra cruft after the quoted-string. */
while ((c = *p) != '\0' && c != ';')
p++;
} else {
/* No. Just scan forward looking for a '\0' (end
of string) or ';' (end of parameter). */
while ((c = *p) != '\0' && c != ';')
p++;
}
if (c == '\0') {
/* End of string, so end of parameter */
if (retvaluelen != NULL) {
*retvaluelen = (gsize) (p - valuep);
}
*nextp = p;
return namep;
}
/* End of parameter; point past the terminating ';' */
if (retvaluelen != NULL) {
*retvaluelen = (gsize) (p - valuep);
}
*nextp = p + 1;
return namep;
}
char *
ws_find_media_type_parameter(wmem_allocator_t *scope, const char *parameters, const char *key)
{
const char *p, *name, *value;
char c;
gsize keylen, namelen, valuelen;
char *valuestr, *vp;
if (parameters == NULL || key == NULL)
/* we won't be able to find anything */
return NULL;
keylen = (gsize) strlen(key);
if (keylen == 0) {
/* There's no parameter name to searh for */
return NULL;
}
p = parameters;
if (*p == '\0') {
/* There are no parameters in which to search */
return NULL;
}
do {
/* Get the next parameter. */
name = ws_get_next_media_type_parameter(p, &namelen, &value,
&valuelen, &p);
if (name == NULL) {
/* No more parameters - not found. */
return NULL;
}
/* Is it the parameter we're looking for? */
if (namelen == keylen && g_ascii_strncasecmp(name, key, keylen) == 0) {
/* Yes. */
break;
}
} while (*p);
if (value == NULL) {
/* The parameter doesn't have a value. */
return NULL;
}
/* We found the parameter with that name; now extract the value. */
valuestr = (char *)wmem_alloc(scope, valuelen + 1);
vp = valuestr;
p = value;
/* Is the value a quoted string? */
if (*p == '"') {
/* Yes. Skip the opening quote, and scan forward looking for
a non-escaped closing quote, copying characters. */
p++;
for (;;) {
c = *p;
if (c == '\0') {
/* End-of-string. We're done.
(XXX - this is an error.) */
*vp = '\0';
return valuestr;
}
if (c == '"') {
/* Closing quote. Skip it; we're done with
the quoted-string. */
p++;
break;
}
if (c == '\\') {
/* Backslash; this escapes the next character
(quoted-pair). Skip the backslash, and make
sure there *is* a next character. */
p++;
if (*p == '\0') {
/* Nothing left; we're done.
(XXX - this is an error.) */
break;
}
}
/* Copy the character. */
*vp++ = *p++;
}
} else {
/* No. Just scan forward until we see a '\0' (end of
string or a non-token character, copying characters. */
while ((c = *p) != '\0' && g_ascii_isgraph(c) && c != '(' &&
c != ')' && c != '<' && c != '>' && c != '@' &&
c != ',' && c != ';' && c != ':' && c != '\\' &&
c != '"' && c != '/' && c != '[' && c != ']' &&
c != '?' && c != '=' && c != '{' && c != '}') {
*vp++ = c;
p++;
}
}
*vp = '\0';
return valuestr;
}
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