path: root/src/mod_rewrite.c

#include "first.h"

#include "base.h"
#include "log.h"
#include "buffer.h"

#include "plugin.h"
#include "stat_cache.h"

#include <ctype.h>
#include <stdlib.h>
#include <string.h>

#if defined(WITH_PCRE)
typedef struct {
	pcre *key;

	buffer *value;

	int once;
} rewrite_rule;

typedef struct {
	rewrite_rule **ptr;

	size_t used;
	size_t size;
} rewrite_rule_buffer;

typedef struct {
	rewrite_rule_buffer *rewrite;
	rewrite_rule_buffer *rewrite_NF;
	data_config *context, *context_NF; /* to which apply me */
} plugin_config;

typedef struct {
	enum { REWRITE_STATE_UNSET, REWRITE_STATE_FINISHED} state;
	int loops;
} handler_ctx;

typedef struct {
	PLUGIN_DATA;
	buffer *match_buf;

	plugin_config **config_storage;

	plugin_config conf;
} plugin_data;

static handler_ctx * handler_ctx_init(void) {
	handler_ctx * hctx;

	hctx = calloc(1, sizeof(*hctx));

	hctx->state = REWRITE_STATE_UNSET;
	hctx->loops = 0;

	return hctx;
}

static void handler_ctx_free(handler_ctx *hctx) {
	free(hctx);
}

static rewrite_rule_buffer *rewrite_rule_buffer_init(void) {
	rewrite_rule_buffer *kvb;

	kvb = calloc(1, sizeof(*kvb));

	return kvb;
}

static int rewrite_rule_buffer_append(rewrite_rule_buffer *kvb, buffer *key, buffer *value, int once) {
	size_t i;
	const char *errptr;
	int erroff;

	if (!key) return -1;

	if (kvb->size == 0) {
		kvb->size = 4;
		kvb->used = 0;

		kvb->ptr = malloc(kvb->size * sizeof(*kvb->ptr));

		for(i = 0; i < kvb->size; i++) {
			kvb->ptr[i] = calloc(1, sizeof(**kvb->ptr));
		}
	} else if (kvb->used == kvb->size) {
		kvb->size += 4;

		kvb->ptr = realloc(kvb->ptr, kvb->size * sizeof(*kvb->ptr));

		for(i = kvb->used; i < kvb->size; i++) {
			kvb->ptr[i] = calloc(1, sizeof(**kvb->ptr));
		}
	}

	if (NULL == (kvb->ptr[kvb->used]->key = pcre_compile(key->ptr,
							    0, &errptr, &erroff, NULL))) {

		return -1;
	}

	kvb->ptr[kvb->used]->value = buffer_init();
	buffer_copy_buffer(kvb->ptr[kvb->used]->value, value);
	kvb->ptr[kvb->used]->once = once;

	kvb->used++;

	return 0;
}

static void rewrite_rule_buffer_free(rewrite_rule_buffer *kvb) {
	size_t i;

	for (i = 0; i < kvb->size; i++) {
		if (kvb->ptr[i]->key) pcre_free(kvb->ptr[i]->key);
		if (kvb->ptr[i]->value) buffer_free(kvb->ptr[i]->value);
		free(kvb->ptr[i]);
	}

	if (kvb->ptr) free(kvb->ptr);

	free(kvb);
}


INIT_FUNC(mod_rewrite_init) {
	plugin_data *p;

	p = calloc(1, sizeof(*p));

	p->match_buf = buffer_init();

	return p;
}

FREE_FUNC(mod_rewrite_free) {
	plugin_data *p = p_d;

	UNUSED(srv);

	if (!p) return HANDLER_GO_ON;

	buffer_free(p->match_buf);
	if (p->config_storage) {
		size_t i;
		for (i = 0; i < srv->config_context->used; i++) {
			plugin_config *s = p->config_storage[i];

			if (NULL == s) continue;

			rewrite_rule_buffer_free(s->rewrite);
			rewrite_rule_buffer_free(s->rewrite_NF);

			free(s);
		}
		free(p->config_storage);
	}

	free(p);

	return HANDLER_GO_ON;
}

static int parse_config_entry(server *srv, array *ca, rewrite_rule_buffer *kvb, const char *option, size_t olen, int once) {
	data_unset *du;

	if (NULL != (du = array_get_element_klen(ca, option, olen))) {
		data_array *da;
		size_t j;

		da = (data_array *)du;

		if (du->type != TYPE_ARRAY || !array_is_kvstring(da->value)) {
			log_error_write(srv, __FILE__, __LINE__, "SSS",
					"unexpected value for ", option, "; expected list of \"regex\" => \"subst\"");
			return HANDLER_ERROR;
		}

		for (j = 0; j < da->value->used; j++) {
			if (0 != rewrite_rule_buffer_append(kvb,
							    ((data_string *)(da->value->data[j]))->key,
							    ((data_string *)(da->value->data[j]))->value,
							    once)) {
				log_error_write(srv, __FILE__, __LINE__, "sb",
						"pcre-compile failed for", da->value->data[j]->key);
				return HANDLER_ERROR;
			}
		}
	}

	return 0;
}
#else
static int parse_config_entry(server *srv, array *ca, const char *option, size_t olen) {
	static int logged_message = 0;
	if (logged_message) return 0;
	if (NULL != array_get_element_klen(ca, option, olen)) {
		logged_message = 1;
		log_error_write(srv, __FILE__, __LINE__, "s",
			"pcre support is missing, please install libpcre and the headers");
	}
	return 0;
}
#endif

SETDEFAULTS_FUNC(mod_rewrite_set_defaults) {
	size_t i = 0;
	config_values_t cv[] = {
		{ "url.rewrite-repeat",        NULL, T_CONFIG_LOCAL, T_CONFIG_SCOPE_CONNECTION }, /* 0 */
		{ "url.rewrite-once",          NULL, T_CONFIG_LOCAL, T_CONFIG_SCOPE_CONNECTION }, /* 1 */

		/* these functions only rewrite if the target is not already in the filestore
		 *
		 * url.rewrite-repeat-if-not-file is the equivalent of url.rewrite-repeat
		 * url.rewrite-if-not-file is the equivalent of url.rewrite-once
		 *
		 */
		{ "url.rewrite-repeat-if-not-file", NULL, T_CONFIG_LOCAL, T_CONFIG_SCOPE_CONNECTION }, /* 2 */
		{ "url.rewrite-if-not-file",        NULL, T_CONFIG_LOCAL, T_CONFIG_SCOPE_CONNECTION }, /* 3 */

		/* old names, still supported
		 *
		 * url.rewrite remapped to url.rewrite-once
		 * url.rewrite-final    is url.rewrite-once
		 *
		 */
		{ "url.rewrite",               NULL, T_CONFIG_LOCAL, T_CONFIG_SCOPE_CONNECTION }, /* 4 */
		{ "url.rewrite-final",         NULL, T_CONFIG_LOCAL, T_CONFIG_SCOPE_CONNECTION }, /* 5 */
		{ NULL,                        NULL, T_CONFIG_UNSET, T_CONFIG_SCOPE_UNSET }
	};

#if defined(WITH_PCRE)
	plugin_data *p = p_d;

	if (!p) return HANDLER_ERROR;

	/* 0 */
	p->config_storage = calloc(1, srv->config_context->used * sizeof(plugin_config *));
#else
	UNUSED(p_d);
#endif

	for (i = 0; i < srv->config_context->used; i++) {
		data_config const* config = (data_config const*)srv->config_context->data[i];
#if defined(WITH_PCRE)
		plugin_config *s;

		s = calloc(1, sizeof(plugin_config));
		s->rewrite = rewrite_rule_buffer_init();
		s->rewrite_NF = rewrite_rule_buffer_init();
		p->config_storage[i] = s;
#endif

		if (0 != config_insert_values_global(srv, config->value, cv, i == 0 ? T_CONFIG_SCOPE_SERVER : T_CONFIG_SCOPE_CONNECTION)) {
			return HANDLER_ERROR;
		}

#if !defined(WITH_PCRE)
# define parse_config_entry(srv, ca, x, option, y) parse_config_entry(srv, ca, option)
#endif
		parse_config_entry(srv, config->value, s->rewrite, CONST_STR_LEN("url.rewrite-once"),      1);
		parse_config_entry(srv, config->value, s->rewrite, CONST_STR_LEN("url.rewrite-final"),     1);
		parse_config_entry(srv, config->value, s->rewrite_NF, CONST_STR_LEN("url.rewrite-if-not-file"),   1);
		parse_config_entry(srv, config->value, s->rewrite_NF, CONST_STR_LEN("url.rewrite-repeat-if-not-file"), 0);
		parse_config_entry(srv, config->value, s->rewrite, CONST_STR_LEN("url.rewrite"),           1);
		parse_config_entry(srv, config->value, s->rewrite, CONST_STR_LEN("url.rewrite-repeat"),    0);
	}

	return HANDLER_GO_ON;
}

#if defined(WITH_PCRE)

#define PATCH(x) \
	p->conf.x = s->x;
static int mod_rewrite_patch_connection(server *srv, connection *con, plugin_data *p) {
	size_t i, j;
	plugin_config *s = p->config_storage[0];

	PATCH(rewrite);
	PATCH(rewrite_NF);
	p->conf.context = NULL;
	p->conf.context_NF = NULL;

	/* skip the first, the global context */
	for (i = 1; i < srv->config_context->used; i++) {
		data_config *dc = (data_config *)srv->config_context->data[i];
		s = p->config_storage[i];

		/* condition didn't match */
		if (!config_check_cond(srv, con, dc)) continue;

		/* merge config */
		for (j = 0; j < dc->value->used; j++) {
			data_unset *du = dc->value->data[j];

			if (buffer_is_equal_string(du->key, CONST_STR_LEN("url.rewrite"))) {
				PATCH(rewrite);
				p->conf.context = dc;
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("url.rewrite-once"))) {
				PATCH(rewrite);
				p->conf.context = dc;
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("url.rewrite-repeat"))) {
				PATCH(rewrite);
				p->conf.context = dc;
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("url.rewrite-if-not-file"))) {
				PATCH(rewrite_NF);
				p->conf.context_NF = dc;
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("url.rewrite-repeat-if-not-file"))) {
				PATCH(rewrite_NF);
				p->conf.context_NF = dc;
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("url.rewrite-final"))) {
				PATCH(rewrite);
				p->conf.context = dc;
			}
		}
	}

	return 0;
}

URIHANDLER_FUNC(mod_rewrite_con_reset) {
	plugin_data *p = p_d;

	UNUSED(srv);

	if (con->plugin_ctx[p->id]) {
		handler_ctx_free(con->plugin_ctx[p->id]);
		con->plugin_ctx[p->id] = NULL;
	}

	return HANDLER_GO_ON;
}

static handler_t process_rewrite_rules(server *srv, connection *con, plugin_data *p, rewrite_rule_buffer *kvb) {
	size_t i;
	handler_ctx *hctx;

	if (con->plugin_ctx[p->id]) {
		hctx = con->plugin_ctx[p->id];

		if (hctx->loops++ > 100) {
			data_config *dc = p->conf.context;
			log_error_write(srv, __FILE__, __LINE__,  "SbbSBS",
					"ENDLESS LOOP IN rewrite-rule DETECTED ... aborting request, perhaps you want to use url.rewrite-once instead of url.rewrite-repeat ($", dc->comp_key, dc->op, "\"", dc->string, "\")");

			return HANDLER_ERROR;
		}

		if (hctx->state == REWRITE_STATE_FINISHED) return HANDLER_GO_ON;
	}

	buffer_copy_buffer(p->match_buf, con->request.uri);

	for (i = 0; i < kvb->used; i++) {
		pcre *match;
		const char *pattern;
		size_t pattern_len;
		int n;
		rewrite_rule *rule = kvb->ptr[i];
# define N 10
		int ovec[N * 3];

		match       = rule->key;
		pattern     = rule->value->ptr;
		pattern_len = buffer_string_length(rule->value);

		if ((n = pcre_exec(match, NULL, CONST_BUF_LEN(p->match_buf), 0, 0, ovec, 3 * N)) < 0) {
			if (n != PCRE_ERROR_NOMATCH) {
				log_error_write(srv, __FILE__, __LINE__, "sd",
						"execution error while matching: ", n);
				return HANDLER_ERROR;
			}
		} else if (0 == pattern_len) {
			/* short-circuit if blank replacement pattern
			 * (do not attempt to match against remaining rewrite rules) */
			return HANDLER_GO_ON;
		} else {
			const char **list;
			size_t start;
			size_t k;

			/* it matched */
			pcre_get_substring_list(p->match_buf->ptr, ovec, n, &list);

			/* search for $[0-9] */

			buffer_reset(con->request.uri);

			start = 0;
			for (k = 0; k+1 < pattern_len; k++) {
				if (pattern[k] == '$' || pattern[k] == '%') {
					/* got one */

					size_t num = pattern[k + 1] - '0';

					buffer_append_string_len(con->request.uri, pattern + start, k - start);

					if (!isdigit((unsigned char)pattern[k + 1])) {
						/* enable escape: "%%" => "%", "%a" => "%a", "$$" => "$" */
						buffer_append_string_len(con->request.uri, pattern+k, pattern[k] == pattern[k+1] ? 1 : 2);
					} else if (pattern[k] == '$') {
						/* n is always > 0 */
						if (num < (size_t)n) {
							buffer_append_string(con->request.uri, list[num]);
						}
					} else if (p->conf.context == NULL) {
						/* we have no context, we are global */
						log_error_write(srv, __FILE__, __LINE__, "sb",
								"used a redirect containing a %[0-9]+ in the global scope, ignored:",
								rule->value);

					} else {
						config_append_cond_match_buffer(con, p->conf.context, con->request.uri, num);
					}

					k++;
					start = k + 1;
				}
			}

			buffer_append_string_len(con->request.uri, pattern + start, pattern_len - start);

			pcre_free(list);

			if (con->plugin_ctx[p->id] == NULL) {
				hctx = handler_ctx_init();
				con->plugin_ctx[p->id] = hctx;
			} else {
				hctx = con->plugin_ctx[p->id];
			}

			if (rule->once) hctx->state = REWRITE_STATE_FINISHED;

			return HANDLER_COMEBACK;
		}
#undef N
	}

	return HANDLER_GO_ON;
}

URIHANDLER_FUNC(mod_rewrite_physical) {
	plugin_data *p = p_d;
	handler_t r;
	stat_cache_entry *sce;

	if (con->mode != DIRECT) return HANDLER_GO_ON;

	mod_rewrite_patch_connection(srv, con, p);
	p->conf.context = p->conf.context_NF;

	if (!p->conf.rewrite_NF) return HANDLER_GO_ON;

	/* skip if physical.path is a regular file */
	sce = NULL;
	if (HANDLER_ERROR != stat_cache_get_entry(srv, con, con->physical.path, &sce)) {
		if (S_ISREG(sce->st.st_mode)) return HANDLER_GO_ON;
	}

	switch(r = process_rewrite_rules(srv, con, p, p->conf.rewrite_NF)) {
	case HANDLER_COMEBACK:
		buffer_reset(con->physical.path);
		/* fall through */
	default:
		return r;
	}

	return HANDLER_GO_ON;
}

URIHANDLER_FUNC(mod_rewrite_uri_handler) {
	plugin_data *p = p_d;

	mod_rewrite_patch_connection(srv, con, p);

	if (!p->conf.rewrite) return HANDLER_GO_ON;

	return process_rewrite_rules(srv, con, p, p->conf.rewrite);
}
#endif

int mod_rewrite_plugin_init(plugin *p);
int mod_rewrite_plugin_init(plugin *p) {
	p->version     = LIGHTTPD_VERSION_ID;
	p->name        = buffer_init_string("rewrite");

#if defined(WITH_PCRE)
	p->init        = mod_rewrite_init;
	/* it has to stay _raw as we are matching on uri + querystring
	 */

	p->handle_uri_raw = mod_rewrite_uri_handler;
	p->handle_physical = mod_rewrite_physical;
	p->cleanup     = mod_rewrite_free;
	p->connection_reset = mod_rewrite_con_reset;
#endif
	p->set_defaults = mod_rewrite_set_defaults;

	p->data        = NULL;

	return 0;
}