1/*
2 * m_ematch.c		Extended Matches
3 *
4 *		This program is free software; you can distribute it and/or
5 *		modify it under the terms of the GNU General Public License
6 *		as published by the Free Software Foundation; either version
7 *		2 of the License, or (at your option) any later version.
8 *
9 * Authors:	Thomas Graf <tgraf@suug.ch>
10 */
11
12#include <stdio.h>
13#include <stdlib.h>
14#include <unistd.h>
15#include <syslog.h>
16#include <fcntl.h>
17#include <sys/socket.h>
18#include <netinet/in.h>
19#include <arpa/inet.h>
20#include <string.h>
21#include <dlfcn.h>
22#include <stdarg.h>
23#include <errno.h>
24
25#include "utils.h"
26#include "tc_util.h"
27#include "m_ematch.h"
28
29#define EMATCH_MAP "/etc/iproute2/ematch_map"
30
31static struct ematch_util *ematch_list;
32
33/* export to bison parser */
34int ematch_argc;
35char **ematch_argv;
36char *ematch_err = NULL;
37struct ematch *ematch_root;
38
39static int begin_argc;
40static char **begin_argv;
41
42static inline void map_warning(int num, char *kind)
43{
44	fprintf(stderr,
45	    "Error: Unable to find ematch \"%s\" in %s\n" \
46	    "Please assign a unique ID to the ematch kind the suggested " \
47	    "entry is:\n" \
48	    "\t%d\t%s\n",
49	    kind, EMATCH_MAP, num, kind);
50}
51
52static int lookup_map(__u16 num, char *dst, int len, const char *file)
53{
54	int err = -EINVAL;
55	char buf[512];
56	FILE *fd = fopen(file, "r");
57
58	if (fd == NULL)
59		return -errno;
60
61	while (fgets(buf, sizeof(buf), fd)) {
62		char namebuf[512], *p = buf;
63		int id;
64
65		while (*p == ' ' || *p == '\t')
66			p++;
67		if (*p == '#' || *p == '\n' || *p == 0)
68			continue;
69
70		if (sscanf(p, "%d %s", &id, namebuf) != 2) {
71			fprintf(stderr, "ematch map %s corrupted at %s\n",
72			    file, p);
73			goto out;
74		}
75
76		if (id == num) {
77			if (dst)
78				strncpy(dst, namebuf, len - 1);
79			err = 0;
80			goto out;
81		}
82	}
83
84	err = -ENOENT;
85out:
86	fclose(fd);
87	return err;
88}
89
90static int lookup_map_id(char *kind, int *dst, const char *file)
91{
92	int err = -EINVAL;
93	char buf[512];
94	FILE *fd = fopen(file, "r");
95
96	if (fd == NULL)
97		return -errno;
98
99	while (fgets(buf, sizeof(buf), fd)) {
100		char namebuf[512], *p = buf;
101		int id;
102
103		while (*p == ' ' || *p == '\t')
104			p++;
105		if (*p == '#' || *p == '\n' || *p == 0)
106			continue;
107
108		if (sscanf(p, "%d %s", &id, namebuf) != 2) {
109			fprintf(stderr, "ematch map %s corrupted at %s\n",
110			    file, p);
111			goto out;
112		}
113
114		if (!strcasecmp(namebuf, kind)) {
115			if (dst)
116				*dst = id;
117			err = 0;
118			goto out;
119		}
120	}
121
122	err = -ENOENT;
123	*dst = 0;
124out:
125	fclose(fd);
126	return err;
127}
128
129static struct ematch_util *get_ematch_kind(char *kind)
130{
131	static void *body;
132	void *dlh;
133	char buf[256];
134	struct ematch_util *e;
135
136	for (e = ematch_list; e; e = e->next) {
137		if (strcmp(e->kind, kind) == 0)
138			return e;
139	}
140
141	snprintf(buf, sizeof(buf), "em_%s.so", kind);
142	dlh = dlopen(buf, RTLD_LAZY);
143	if (dlh == NULL) {
144		dlh = body;
145		if (dlh == NULL) {
146			dlh = body = dlopen(NULL, RTLD_LAZY);
147			if (dlh == NULL)
148				return NULL;
149		}
150	}
151
152	snprintf(buf, sizeof(buf), "%s_ematch_util", kind);
153	e = dlsym(dlh, buf);
154	if (e == NULL)
155		return NULL;
156
157	e->next = ematch_list;
158	ematch_list = e;
159
160	return e;
161}
162
163static struct ematch_util *get_ematch_kind_num(__u16 kind)
164{
165	char name[32];
166
167	if (lookup_map(kind, name, sizeof(name), EMATCH_MAP) < 0)
168		return NULL;
169
170	return get_ematch_kind(name);
171
172	return NULL;
173}
174
175static int parse_tree(struct nlmsghdr *n, struct ematch *tree)
176{
177	int index = 1;
178	struct ematch *t;
179
180	for (t = tree; t; t = t->next) {
181		struct rtattr *tail = NLMSG_TAIL(n);
182		struct tcf_ematch_hdr hdr = {
183			.flags = t->relation
184		};
185
186		if (t->inverted)
187			hdr.flags |= TCF_EM_INVERT;
188
189		addattr_l(n, MAX_MSG, index++, NULL, 0);
190
191		if (t->child) {
192			__u32 r = t->child_ref;
193			addraw_l(n, MAX_MSG, &hdr, sizeof(hdr));
194			addraw_l(n, MAX_MSG, &r, sizeof(r));
195		} else {
196			int num = 0, err;
197			char buf[64];
198			struct ematch_util *e;
199
200			if (t->args == NULL)
201				return -1;
202
203			strncpy(buf, (char*) t->args->data, sizeof(buf)-1);
204			e = get_ematch_kind(buf);
205			if (e == NULL) {
206				fprintf(stderr, "Unknown ematch \"%s\"\n",
207				    buf);
208				return -1;
209			}
210
211			err = lookup_map_id(buf, &num, EMATCH_MAP);
212			if (err < 0) {
213				if (err == -ENOENT)
214					map_warning(e->kind_num, buf);
215				return err;
216			}
217
218			hdr.kind = num;
219			if (e->parse_eopt(n, &hdr, t->args->next) < 0)
220				return -1;
221		}
222
223		tail->rta_len = (void*) NLMSG_TAIL(n) - (void*) tail;
224	}
225
226	return 0;
227}
228
229static int flatten_tree(struct ematch *head, struct ematch *tree)
230{
231	int i, count = 0;
232	struct ematch *t;
233
234	for (;;) {
235		count++;
236
237		if (tree->child) {
238			for (t = head; t->next; t = t->next);
239			t->next = tree->child;
240			count += flatten_tree(head, tree->child);
241		}
242
243		if (tree->relation == 0)
244			break;
245
246		tree = tree->next;
247	}
248
249	for (i = 0, t = head; t; t = t->next, i++)
250		t->index = i;
251
252	for (t = head; t; t = t->next)
253		if (t->child)
254			t->child_ref = t->child->index;
255
256	return count;
257}
258
259int em_parse_error(int err, struct bstr *args, struct bstr *carg,
260		   struct ematch_util *e, char *fmt, ...)
261{
262	va_list a;
263
264	va_start(a, fmt);
265	vfprintf(stderr, fmt, a);
266	va_end(a);
267
268	if (ematch_err)
269		fprintf(stderr, ": %s\n... ", ematch_err);
270	else
271		fprintf(stderr, "\n... ");
272
273	while (ematch_argc < begin_argc) {
274		if (ematch_argc == (begin_argc - 1))
275			fprintf(stderr, ">>%s<< ", *begin_argv);
276		else
277			fprintf(stderr, "%s ", *begin_argv);
278		begin_argv++;
279		begin_argc--;
280	}
281
282	fprintf(stderr, "...\n");
283
284	if (args) {
285		fprintf(stderr, "... %s(", e->kind);
286		while (args) {
287			fprintf(stderr, "%s", args == carg ? ">>" : "");
288			bstr_print(stderr, args, 1);
289			fprintf(stderr, "%s%s", args == carg ? "<<" : "",
290			    args->next ? " " : "");
291			args = args->next;
292		}
293		fprintf(stderr, ")...\n");
294
295	}
296
297	if (e == NULL) {
298		fprintf(stderr,
299		    "Usage: EXPR\n" \
300		    "where: EXPR  := TERM [ { and | or } EXPR ]\n" \
301		    "       TERM  := [ not ] { MATCH | '(' EXPR ')' }\n" \
302		    "       MATCH := module '(' ARGS ')'\n" \
303		    "       ARGS := ARG1 ARG2 ...\n" \
304		    "\n" \
305		    "Example: a(x y) and not (b(x) or c(x y z))\n");
306	} else
307		e->print_usage(stderr);
308
309	return -err;
310}
311
312static inline void free_ematch_err(void)
313{
314	if (ematch_err) {
315		free(ematch_err);
316		ematch_err = NULL;
317	}
318}
319
320extern int ematch_parse(void);
321
322int parse_ematch(int *argc_p, char ***argv_p, int tca_id, struct nlmsghdr *n)
323{
324	begin_argc = ematch_argc = *argc_p;
325	begin_argv = ematch_argv = *argv_p;
326
327	if (ematch_parse()) {
328		int err = em_parse_error(EINVAL, NULL, NULL, NULL,
329		    "Parse error");
330		free_ematch_err();
331		return err;
332	}
333
334	free_ematch_err();
335
336	/* undo look ahead by parser */
337	ematch_argc++;
338	ematch_argv--;
339
340	if (ematch_root) {
341		struct rtattr *tail, *tail_list;
342
343		struct tcf_ematch_tree_hdr hdr = {
344			.nmatches = flatten_tree(ematch_root, ematch_root),
345			.progid = TCF_EM_PROG_TC
346		};
347
348		tail = NLMSG_TAIL(n);
349		addattr_l(n, MAX_MSG, tca_id, NULL, 0);
350		addattr_l(n, MAX_MSG, TCA_EMATCH_TREE_HDR, &hdr, sizeof(hdr));
351
352		tail_list = NLMSG_TAIL(n);
353		addattr_l(n, MAX_MSG, TCA_EMATCH_TREE_LIST, NULL, 0);
354
355		if (parse_tree(n, ematch_root) < 0)
356			return -1;
357
358		tail_list->rta_len = (void*) NLMSG_TAIL(n) - (void*) tail_list;
359		tail->rta_len = (void*) NLMSG_TAIL(n) - (void*) tail;
360	}
361
362	*argc_p = ematch_argc;
363	*argv_p = ematch_argv;
364
365	return 0;
366}
367
368static int print_ematch_seq(FILE *fd, struct rtattr **tb, int start,
369			    int prefix)
370{
371	int n, i = start;
372	struct tcf_ematch_hdr *hdr;
373	int dlen;
374	void *data;
375
376	for (;;) {
377		if (tb[i] == NULL)
378			return -1;
379
380		dlen = RTA_PAYLOAD(tb[i]) - sizeof(*hdr);
381		data = (void *) RTA_DATA(tb[i]) + sizeof(*hdr);
382
383		if (dlen < 0)
384			return -1;
385
386		hdr = RTA_DATA(tb[i]);
387
388		if (hdr->flags & TCF_EM_INVERT)
389			fprintf(fd, "NOT ");
390
391		if (hdr->kind == 0) {
392			__u32 ref;
393
394			if (dlen < sizeof(__u32))
395				return -1;
396
397			ref = *(__u32 *) data;
398			fprintf(fd, "(\n");
399			for (n = 0; n <= prefix; n++)
400				fprintf(fd, "  ");
401			if (print_ematch_seq(fd, tb, ref + 1, prefix + 1) < 0)
402				return -1;
403			for (n = 0; n < prefix; n++)
404				fprintf(fd, "  ");
405			fprintf(fd, ") ");
406
407		} else {
408			struct ematch_util *e;
409
410			e = get_ematch_kind_num(hdr->kind);
411			if (e == NULL)
412				fprintf(fd, "[unknown ematch %d]\n",
413				    hdr->kind);
414			else {
415				fprintf(fd, "%s(", e->kind);
416				if (e->print_eopt(fd, hdr, data, dlen) < 0)
417					return -1;
418				fprintf(fd, ")\n");
419			}
420			if (hdr->flags & TCF_EM_REL_MASK)
421				for (n = 0; n < prefix; n++)
422					fprintf(fd, "  ");
423		}
424
425		switch (hdr->flags & TCF_EM_REL_MASK) {
426			case TCF_EM_REL_AND:
427				fprintf(fd, "AND ");
428				break;
429
430			case TCF_EM_REL_OR:
431				fprintf(fd, "OR ");
432				break;
433
434			default:
435				return 0;
436		}
437
438		i++;
439	}
440
441	return 0;
442}
443
444static int print_ematch_list(FILE *fd, struct tcf_ematch_tree_hdr *hdr,
445			     struct rtattr *rta)
446{
447	int err = -1;
448	struct rtattr **tb;
449
450	tb = malloc((hdr->nmatches + 1) * sizeof(struct rtattr *));
451	if (tb == NULL)
452		return -1;
453
454	if (hdr->nmatches > 0) {
455		if (parse_rtattr_nested(tb, hdr->nmatches, rta) < 0)
456			goto errout;
457
458		fprintf(fd, "\n  ");
459		if (print_ematch_seq(fd, tb, 1, 1) < 0)
460			goto errout;
461	}
462
463	err = 0;
464errout:
465	free(tb);
466	return err;
467}
468
469int print_ematch(FILE *fd, const struct rtattr *rta)
470{
471	struct rtattr *tb[TCA_EMATCH_TREE_MAX+1];
472	struct tcf_ematch_tree_hdr *hdr;
473
474	if (parse_rtattr_nested(tb, TCA_EMATCH_TREE_MAX, rta) < 0)
475		return -1;
476
477	if (tb[TCA_EMATCH_TREE_HDR] == NULL) {
478		fprintf(stderr, "Missing ematch tree header\n");
479		return -1;
480	}
481
482	if (tb[TCA_EMATCH_TREE_LIST] == NULL) {
483		fprintf(stderr, "Missing ematch tree list\n");
484		return -1;
485	}
486
487	if (RTA_PAYLOAD(tb[TCA_EMATCH_TREE_HDR]) < sizeof(*hdr)) {
488		fprintf(stderr, "Ematch tree header size mismatch\n");
489		return -1;
490	}
491
492	hdr = RTA_DATA(tb[TCA_EMATCH_TREE_HDR]);
493
494	return print_ematch_list(fd, hdr, tb[TCA_EMATCH_TREE_LIST]);
495}
496