/* dfilter-macro.c
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 2001 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */


#include "config.h"
#define WS_LOG_DOMAIN LOG_DOMAIN_DFILTER
#include "dfilter-macro.h"

#ifdef DUMP_DFILTER_MACRO
#include <stdio.h>
#endif
#include <string.h>

#include "dfilter-int.h"
#include <ftypes/ftypes.h>
#include <epan/uat-int.h>
#include <epan/proto.h>
#include <wsutil/glib-compat.h>


static uat_t* dfilter_macro_uat = NULL;
static dfilter_macro_t* macros = NULL;
static unsigned num_macros;

/* #define DUMP_DFILTER_MACRO */
#ifdef DUMP_DFILTER_MACRO
void dump_dfilter_macro_t(const dfilter_macro_t *m, const char *function, const char *file, int line);
#define DUMP_MACRO(m) dump_dfilter_macro_t(m, G_STRFUNC, __FILE__, __LINE__)
#else
#define DUMP_MACRO(m)
#endif

static char* dfilter_macro_resolve(char* name, char** args, df_error_t** error) {
	GString* text;
	int argc = 0;
	dfilter_macro_t* m = NULL;
	int* arg_pos_p;
	char** parts;
	char* ret;
	unsigned i;

	for (i = 0; i < num_macros; i++) {
		dfilter_macro_t* c = &(macros[i]);
		if ( c->usable && g_str_equal(c->name,name) ) {
			m = c;
			break;
		}
	}

	if (!m) {
		if (error != NULL)
			*error = df_error_new_printf(DF_ERROR_GENERIC, NULL, "macro '%s' does not exist", name);
		return NULL;
	}

	DUMP_MACRO(m);

	if (args) {
		while(args[argc]) argc++;
	}

	if (argc != m->argc) {
		if (error != NULL) {
			*error = df_error_new_printf(DF_ERROR_GENERIC, NULL,
							"wrong number of arguments for macro '%s', expecting %d instead of %d",
							name, m->argc, argc);
		}
		return NULL;
	}

	arg_pos_p = m->args_pos;
	parts = m->parts;

	text = g_string_new(*(parts++));

	if (args) {
		while (*parts) {
			g_string_append_printf(text,"%s%s",
					       args[*(arg_pos_p++)],
					       *(parts++));
		}
	}

	ret = wmem_strdup(NULL, text->str);

	g_string_free(text,true);

	return ret;
}

/* Start points to the first character after "${" */
static bool start_is_field_reference(const char *start)
{
	const char *end;
	char saved_c;
	const header_field_info *hfinfo;

	end = strchr(start, '#');
	if (end == NULL)
		end = strchr(start, '}');
	if (end == NULL)
		return false;

	saved_c = *end;
	/* This violates constness but we will restore the original string. */
	*(char *)end = '\0';
	/* Search for name in registered fields. */

	if (start[0] == '@')
		start++;

	hfinfo = dfilter_resolve_unparsed(NULL, start);
	/* Restore mangled string. */
	*(char *)end = saved_c;

	if (hfinfo == NULL)
		return false;

	if (hfinfo->type == FT_PROTOCOL || hfinfo->type == FT_NONE) {
		/* Ignore these? */
		return false;
	}

	/* It's a field reference so ignore it as a macro. */
	ws_noisy("Ignore field reference ${%s}", start);
	return true;
}

static char* dfilter_macro_apply_recurse(const char* text, unsigned depth, df_error_t** error) {
	enum { OUTSIDE, STARTING, NAME, ARGS } state = OUTSIDE;
	GString* out;
	GString* name = NULL;
	GString* arg = NULL;
	GPtrArray* args = NULL;
	char c;
	const char* r = text;
	bool changed = false;

	if ( depth > 31) {
		if (error != NULL)
			*error = df_error_new_msg("too much nesting in macros");
		return NULL;
	}

#define FGS(n) if (n) g_string_free(n,true); n = NULL

#define FREE_ALL() \
	do { \
		FGS(name); \
		FGS(arg); \
		if (args) { \
			while(args->len) { void* p = g_ptr_array_remove_index_fast(args,0); g_free(p); } \
			g_ptr_array_free(args,true); \
			args = NULL; \
		} \
	} while(0)

	if (error != NULL)
		*error = NULL;
	out = g_string_sized_new(64);

	while(1) {
		c = *r++;

		switch(state) {
			case OUTSIDE: {
				switch(c) {
					case '\0': {
						goto finish;
					} case '$': {
						state = STARTING;
						break;
					} default: {
						g_string_append_c(out,c);
						break;
					}
				}
				break;
			} case STARTING: {
				switch (c) {
					case '{': {
						if (start_is_field_reference(r)) {
							/* We have a field reference, preserve the name with ${} and bail. */
							g_string_append(out,"${");
							state = OUTSIDE;
							break;
						}

						/* We have a macro, continue. */
						args = g_ptr_array_new();
						arg = g_string_sized_new(32);
						name = g_string_sized_new(32);

						state = NAME;

						break;
					} case '\0': {
						g_string_append_c(out,'$');

						goto finish;
					} default: {
						g_string_append_c(out,'$');
						g_string_append_c(out,c);

						state = OUTSIDE;

						break;
					}
				}
				break;
			} case NAME: {
				if ( g_ascii_isalnum(c) || c == '_' || c == '-' || c == '.' ) {
					g_string_append_c(name,c);
				} else if ( c == ':') {
					state = ARGS;
				} else if ( c == '}') {
					char* resolved;

					g_ptr_array_add(args,NULL);

					resolved = dfilter_macro_resolve(name->str, (char**)args->pdata, error);
					if (resolved == NULL)
						goto on_error;

					changed = true;

					g_string_append(out,resolved);
					wmem_free(NULL, resolved);

					FREE_ALL();

					state = OUTSIDE;
				} else if ( c == '\0') {
					if (error != NULL)
						*error = df_error_new_msg("end of filter in the middle of a macro expression");
					goto on_error;
				} else {
					if (error != NULL)
						*error = df_error_new_msg("invalid character in macro name");
					goto on_error;
				}
				break;
			} case ARGS: {
				switch(c) {
					case '\0': {
						if (error != NULL)
							*error = df_error_new_msg("end of filter in the middle of a macro expression");
						goto on_error;
					} case ';': {
						g_ptr_array_add(args,g_string_free(arg,false));

						arg = g_string_sized_new(32);
						break;
					} case '\\': {
						c = *r++;
						if (c) {
							g_string_append_c(arg,c);
							break;
						} else {
							if (error != NULL)
								*error = df_error_new_msg("end of filter in the middle of a macro expression");
							goto on_error;
						}
					} default: {
						g_string_append_c(arg,c);
						break;
					} case '}': {
						char* resolved;
						g_ptr_array_add(args,g_string_free(arg,false));
						g_ptr_array_add(args,NULL);

						arg = NULL;

						resolved = dfilter_macro_resolve(name->str, (char**)args->pdata, error);
						if (resolved == NULL)
							goto on_error;

						changed = true;

						g_string_append(out,resolved);
						wmem_free(NULL, resolved);

						FREE_ALL();

						state = OUTSIDE;
						break;
					}
				}
				break;
			}
		}
	}

finish:
	{
		FREE_ALL();

		if (changed) {
			char* resolved = dfilter_macro_apply_recurse(out->str, depth + 1, error);
			g_string_free(out,true);
			return resolved;
		} else {
			char* out_str = wmem_strdup(NULL, out->str);
			g_string_free(out,true);
			return out_str;
		}
	}
on_error:
	{
		FREE_ALL();
		if (error != NULL) {
			if (*error == NULL)
				*error = df_error_new_msg("unknown error in macro expression");
		}
		g_string_free(out,true);
		return NULL;
	}
}

char* dfilter_macro_apply(const char* text, df_error_t** error) {
	return dfilter_macro_apply_recurse(text, 0, error);
}

static bool macro_update(void* mp, gchar** error) {
	dfilter_macro_t* m = (dfilter_macro_t*)mp;
	GPtrArray* parts;
	GArray* args_pos;
	const char* r;
	char* w;
	char* part;
	int argc = 0;

	DUMP_MACRO(m);

	*error = NULL;

	/* Invalidate the display filter in case it's in use */
	if (dfilter_macro_uat && dfilter_macro_uat->post_update_cb)
	  dfilter_macro_uat->post_update_cb();

	parts = g_ptr_array_new();
	args_pos = g_array_new(false,false,sizeof(int));

	m->priv = part = w = g_strdup(m->text);
	r = m->text;
	g_ptr_array_add(parts,part);

	while (r && *r) {

		switch (*r) {
			default:
				*(w++) = *(r++);
				break;
			case '\0':
				*w = *r;
				goto done;
			case '\\':
				*(w++) = *(r++);
				if(*r)
					*(w++) = *(r++);
				break;
			case '$': {
				int cnt = 0;
				int arg_pos = 0;
				do {
					char c = *(r+1);
					if (c >= '0' && c <= '9') {
						cnt++;
						r++;
						*(w++) = '\0';
						arg_pos *= 10;
						arg_pos += c - '0';
					} else {
						break;
					}
				} while(*r);

				if (cnt) {
					*(w++) = '\0';
					r++;
					argc = argc < arg_pos ? arg_pos : argc;
					arg_pos--;
					g_array_append_val(args_pos,arg_pos);
					g_ptr_array_add(parts,w);
				} else {
					*(w++) = *(r++);
				}
				break;
			}
		}

	}

done:
	g_ptr_array_add(parts,NULL);

	g_free(m->parts);
	m->parts = (char **)g_ptr_array_free(parts, false);

	g_free(m->args_pos);
	m->args_pos = (int*)(void *)g_array_free(args_pos, false);

	m->argc = argc;

	m->usable = true;

	DUMP_MACRO(m);

	return true;
}

static void macro_free(void* r) {
	dfilter_macro_t* m = (dfilter_macro_t*)r;

	DUMP_MACRO(r);

	g_free(m->name);
	g_free(m->text);
	g_free(m->priv);
	g_free(m->parts);
	g_free(m->args_pos);
}

static void* macro_copy(void* dest, const void* orig, size_t len _U_) {
	dfilter_macro_t* d = (dfilter_macro_t*)dest;
	const dfilter_macro_t* m = (const dfilter_macro_t*)orig;

	DUMP_MACRO(m);

	d->name = g_strdup(m->name);
	d->text = g_strdup(m->text);
	d->usable = m->usable;

	if (m->parts) {
		unsigned nparts = 0;

		/*
		 * Copy the contents of m->priv (a "cooked" version
		 * of m->text) into d->priv.
		 *
		 * First we clone m->text into d->priv, this gets
		 * us a NUL terminated string of the proper length.
		 *
		 * Then we loop copying bytes from m->priv into
		 * d-priv.  Since m->priv contains internal ACSII NULs
		 * we use the length of m->text to stop the copy.
		 */

		d->priv = g_strdup(m->text);
		{
			const char* oldText = m->text;
			const char* oldPriv = (const char*)m->priv;
			char* newPriv = (char*)d->priv;
			while(oldText && *oldText) {
				*(newPriv++) = *(oldPriv++);
				oldText++;
			}
		}

		/*
		 * The contents of the m->parts array contains pointers
		 * into various sections of m->priv.  Since it's
		 * an argv style array of ponters, this array is
		 * actually one larger than the number of parts
		 * to hold the final NULL terminator.
		 *
		 * The following copy clones the original m->parts
		 * array into d->parts but then fixes-up the pointers
		 * so that they point into the appropriate sections
		 * of the d->priv.
		 */

		do nparts++; while (m->parts[nparts]);
		d->parts = (char **)g_memdup2(m->parts,(nparts+1)*(unsigned)sizeof(void*));
		nparts = 0;
		while(m->parts[nparts]) {
			if(nparts) {
				d->parts[nparts] = d->parts[nparts - 1] + (m->parts[nparts] - m->parts[nparts - 1]);
			} else {
				d->parts[nparts] = (char *)d->priv;
			}
			nparts++;
		}

		/*
		 * Clone the contents of m->args_pos into d->args_pos.
		 */

		d->args_pos = (int *)g_memdup2(m->args_pos,(--nparts)*(unsigned)sizeof(int));
	}

	DUMP_MACRO(d);

	return d;
}

static bool macro_name_chk(void *mp, const char *in_name, unsigned name_len,
		const void *u1 _U_, const void *u2 _U_, char **error) {
	dfilter_macro_t* m = (dfilter_macro_t*)mp;
	unsigned i;

	if (name_len == 0) {
		*error = g_strdup("invalid name");
		return false;
	}

	for (i=0; i < name_len; i++) {
		if (!(in_name[i] == '_' || g_ascii_isalnum(in_name[i]) ) ) {
			*error = g_strdup("invalid char in name");
			return false;
		}
	}

	/* When loading (!m->name) or when adding/changing the an item with a
	 * different name, check for uniqueness. NOTE: if a duplicate already
	 * exists (because the user manually edited the file), then this will
	 * not trigger a warning. */
	if (!m->name || g_strcmp0(m->name, in_name)) {
		for (i = 0; i < num_macros; i++) {
			/* This a string field which is always NUL-terminated,
			 * so no need to check name_len. */
			if (!g_strcmp0(in_name, macros[i].name)) {
				*error = ws_strdup_printf("macro '%s' already exists",
							 in_name);
				return false;
			}
		}
	}

	return true;
}

UAT_CSTRING_CB_DEF(macro,name,dfilter_macro_t)
UAT_CSTRING_CB_DEF(macro,text,dfilter_macro_t)

void dfilter_macro_init(void) {
	static uat_field_t uat_fields[] =  {
		UAT_FLD_CSTRING_OTHER(macro,name,"Name",macro_name_chk,"The name of the macro."),
		/* N.B. it would be nice if there was a field type for display filters (with
		   auto-completion & colouring), but this wouldn't work here as the filter string
		   will contain $1, etc... */
		UAT_FLD_CSTRING_ISPRINT(macro,text,"Text","The text this macro resolves to."),
		UAT_END_FIELDS
	};

	dfilter_macro_uat = uat_new("Display Filter Macros",
				    sizeof(dfilter_macro_t),
				    DFILTER_MACRO_FILENAME,
				    true,
				    &macros,
				    &num_macros,
				    UAT_AFFECTS_FIELDS,
				    "ChDisplayFilterMacrosSection",
				    macro_copy,
				    macro_update,
				    macro_free,
				    NULL, /* Note: This is set in macros_init () */
				    NULL,
				    uat_fields);
}

void dfilter_macro_get_uat(uat_t **dfmu_ptr_ptr) {
    *dfmu_ptr_ptr = dfilter_macro_uat;
}

#ifdef DUMP_DFILTER_MACRO
/*
 * The dfilter_macro_t has several characteristics that are
 * not immediately obvious. The dump_dfilter_filter_macro_t()
 * function can be used to help "visualize" the contents of
 * a dfilter_macro_t.
 *
 * Some non-obvious components of this struct include:
 *
 *    m->parts is an argv style array of pointers into the
 *    m->priv string.
 *
 *    The last pointer of an m->parts array should contain
 *    NULL to indicate the end of the parts pointer array.
 *
 *    m->priv is a "cooked" copy of the m->text string.
 *    Any variable substitution indicators within m->text
 *    ("$1", "$2", ...) will have been replaced with ASCII
 *    NUL characters within m->priv.
 *
 *    The first element of m->parts array (m-parts[0]) will
 *    usually have the same pointer value as m->priv (unless
 *    the dfilter-macro starts off with a variable
 *    substitution indicator (e.g. "$1").
 */

void dump_dfilter_macro_t(const dfilter_macro_t *m, const char *function, const char *file, int line)
{
	printf("\n<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");

	if(m == NULL) {
		printf("  dfilter_macro_t * == NULL! (via: %s(): %s:%d)\n", function, file, line);
		printf("\n>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
		return;
	}

	printf("DUMP of dfilter_macro_t: %p (via: %s(): %s:%d)\n", m, function, file, line);

	printf("  &dfilter_macro->name     == %p\n", &m->name);
	if(m->name == NULL) {
		printf("                ->name     == NULL\n");
	} else {
		printf("                ->name     == %p\n", m->name);
		printf("                ->name     == <%s>\n", m->name);
	}

	printf("  &dfilter_macro->text     == %p\n", &m->text);
	if(m->text == NULL) {
		printf("                ->text     == NULL\n");
	} else {
		printf("                ->text     == %p\n", m->text);
		printf("                ->text     == <%s>\n", m->text);
	}

	printf("  &dfilter_macro->usable   == %p\n", &m->usable);
	printf("                ->usable   == %u\n", m->usable);

	printf("  &dfilter_macro->parts    == %p\n", &m->parts);

	if(m->parts == NULL) {
		printf("                ->parts    == NULL\n");
	} else {
		int i = 0;

		while (m->parts[i]) {
			printf("                ->parts[%d] == %p\n", i, m->parts[i]);
			printf("                ->parts[%d] == <%s>\n", i, m->parts[i]);
			i++;
		}
		printf("                ->parts[%d] == NULL\n", i);
	}

	printf("  &dfilter_macro->args_pos == %p\n", &m->args_pos);
	if(m->args_pos == NULL) {
		printf("                ->args_pos == NULL\n");
	} else {
		printf("                ->args_pos == %p\n", m->args_pos);
		/*printf("                ->args_pos == <%?>\n", m->args_pos);*/
	}

	printf("  &dfilter_macro->argc     == %p\n", &m->argc);
	printf("                ->argc     == %d\n", m->argc);

	printf("  &dfilter_macro->priv     == %p\n", &m->priv);
	if(m->priv == NULL) {
		printf("                ->priv     == NULL\n");
	} else {
		printf("                ->priv     == %p\n", m->priv);
		printf("                ->priv     == <%s>\n", (char *)m->priv);
	}

	printf("\n>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
}
#endif

void dfilter_macro_cleanup(void)
{
}

/*
 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 8
 * tab-width: 8
 * indent-tabs-mode: t
 * End:
 *
 * vi: set shiftwidth=8 tabstop=8 noexpandtab:
 * :indentSize=8:tabSize=8:noTabs=false:
 */