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path: root/src/vmod_dbrw.c
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/* This file is part of libvmod_dbrw
   Copyright (C) 2013 Sergey Poznyakoff

   Libvmod_dbrw is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3, or (at your option)
   any later version.

   Libvmod_dbrw is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with libvmod_dbrw.  If not, see <http://www.gnu.org/licenses/>.
*/
#include "dbrw.h"
#include <stdarg.h>
#include <regex.h>
#include "wordsplit.h"
#include "vrt.h"
#include "vcc_if.h"
#include "bin/varnishd/cache.h"

static pthread_once_t thread_once = PTHREAD_ONCE_INIT;
static pthread_key_t thread_key;

enum {
	QDISP_NONE,
	QDISP_APPEND,
	QDISP_DISCARD
};

void
dbrw_debug(const char *fmt, ...)
{
	va_list ap;
	va_start(ap, fmt);
	vsyslog(LOG_DAEMON|LOG_DEBUG, fmt, ap);
	va_end(ap);
}

void
dbrw_error(const char *fmt, ...)
{
	va_list ap;
	va_start(ap, fmt);
	vsyslog(LOG_DAEMON|LOG_ERR, fmt, ap);
	va_end(ap);
}

static void
conn_free(void *f)
{
	struct dbrw_connection *p = f;
	sql_disconnect(p);
	sql_destroy(p);
}

static void
make_key()
{
	pthread_key_create(&thread_key, conn_free);
}

int
dbrw_init(struct vmod_priv *priv, const struct VCL_conf *vclconf)
{
	struct dbrw_config *conf = calloc(1, sizeof(*conf));
	if (!conf) {
		dbrw_error("not enough memory");
		abort();
	}
	priv->priv = conf;
	pthread_once(&thread_once, make_key);
	return 0;
}

char *
findparam(char **params, char *name)
{
	char *p, *q;

	while (*params) {
		p = *params++;
		for (q = name; *p && *q && *p == *q; p++, q++);
		if (*q == 0 && *p == '=')
			return p+1;
	}
	return NULL;
}

static void
argv_free(char **argv)
{
	if (!argv)
		return;
	while (*argv) {
		free(*argv);
		++*argv;
	}
}

static struct dbrw_backend *bcktab[] = {
#ifdef USE_SQL_MYSQL
	&mysql_backend,
#endif
#ifdef USE_SQL_PGSQL
	&pgsql_backend,
#endif
	NULL
};

static struct dbrw_backend *
find_backend(const char *name)
{
	int i;

	for (i = 0; bcktab[i]; i++) {
		if (strcmp(bcktab[i]->name, name) == 0)
			return bcktab[i];
	}
	return NULL;
}

static int
is_http_status(const char *arg)
{
	if (strlen(arg) != HTTP_STATUS_LEN)
		return 0;
	return  '1' <= arg[0] && arg[0] <= '5' &&
		'0' <= arg[1] && arg[1] <= '9' &&
		'0' <= arg[2] && arg[2] <= '9';
}

static int
parse_flags(const char *arg, int *qdisp, int *flags, char status[])
{
	struct wordsplit ws;
	int rc = 0;
	int i;
	
	if (!arg)
		return 0;
	ws.ws_delim = ",";
	if (wordsplit(arg, &ws, 
		      WRDSF_NOVAR | WRDSF_NOCMD | WRDSF_QUOTE |
		      WRDSF_CESCAPES |
		      WRDSF_DELIM)) {
		dbrw_error("cannot split string `%s': %s",
			   arg, wordsplit_strerror (&ws));
		return 1;
	}

	for (i = 0; i < ws.ws_wordc; i++) {
		if (strcmp(ws.ws_wordv[i], "nocase") == 0 ||
		    strcmp(ws.ws_wordv[i], "NC") == 0)
			*flags |= REG_ICASE;
		else if (strcmp(ws.ws_wordv[i], "case") == 0)
			*flags &= ~REG_ICASE;
		else if (strcmp(ws.ws_wordv[i], "qsappend") == 0 ||
			 strcmp(ws.ws_wordv[i], "QSA") == 0)
			*qdisp = QDISP_APPEND;
		else if (strcmp(ws.ws_wordv[i], "qsdiscard") == 0 ||
			 strcmp(ws.ws_wordv[i], "QSD") == 0)
			*qdisp = QDISP_DISCARD;
		else if (strncmp(ws.ws_wordv[i], "redirect=", 9) == 0) {
			if (!is_http_status(ws.ws_wordv[i] + 9)) {
				dbrw_error("invalid status code: %s",
					   ws.ws_wordv[i] + 9);
				rc = 1;
			} else
				strncpy(status, ws.ws_wordv[i] + 9,
					HTTP_STATUS_LEN);
		} else if (strncmp(ws.ws_wordv[i], "R=", 2) == 0) {
			if (!is_http_status(ws.ws_wordv[i] + 2)) {
				dbrw_error("invalid status code: %s",
					   ws.ws_wordv[i] + 2);
				rc = 1;
			} else
				strncpy(status, ws.ws_wordv[i] + 2,
					HTTP_STATUS_LEN);
		} else {
				dbrw_error("unrecognized flag: %s", ws.ws_wordv[i]);
			rc = 1;
		}
	}		   
	
	wordsplit_free(&ws);
	return rc;
}


/* Configure the module.
   BACKEND  - "mysql" or "pgsql"
   PARAM    - VAR=VALUE*:
                 db=S                  
		 port=N
		 socket=S
		 user=S
		 password=S
		 options=S
		 debug=N
   QUERY    - Query to obtain the redirection target   
 */
void
vmod_config(struct sess *sp, struct vmod_priv *priv, const char *bkname,
	    const char *param, const char *query)
{
	char *s;
	struct wordsplit ws;
	struct dbrw_config *conf = priv->priv;
	
	ws.ws_delim = ";";
	if (wordsplit(param, &ws, 
		      WRDSF_NOVAR | WRDSF_NOCMD | WRDSF_QUOTE |
		      WRDSF_CESCAPES |
		      WRDSF_DELIM)) {
		dbrw_error("cannot split string `%s': %s",
			      param, wordsplit_strerror (&ws));
		return;
	}
	conf->param = ws.ws_wordv;
	ws.ws_wordv = NULL;
	ws.ws_wordc = 0;
	wordsplit_free(&ws);

	conf->query = strdup(query);
	if (!conf->query) {
		dbrw_error("not enough memory");
		argv_free(conf->param);
		conf->param = NULL;
		return;
	}

	/* Select backend */
	conf->backend = find_backend(bkname);
	if (!conf->backend) {
		dbrw_error("unsupported backend: %s", bkname);
		argv_free(conf->param);
		free(conf->query);
		conf->query = NULL;
		conf->param = NULL;
		return;
	}

	s = findparam(conf->param, "debug");
	conf->debug_level =  atoi(s);

	conf->qdisp = QDISP_NONE;
	conf->regflags = REG_EXTENDED;
	conf->status[0] = 0;

	s = findparam(conf->param, "flags");
	if (s && parse_flags(s, &conf->qdisp, &conf->regflags, conf->status)) {
		argv_free(conf->param);
		free(conf->query);
		conf->query = NULL;
		conf->param = NULL;
	}
}

static char *
expand_backref(struct sess *sp, const char *str, const char *val,
	       size_t matchcount, regmatch_t *matches, char *qry)
{
	unsigned u;
        char *b, *p;
	
        u = WS_Reserve(sp->wrk->ws, 0);
        p = b = sp->wrk->ws->f;

	while (*val) {
		if (u == 0) {
			WS_Release(sp->wrk->ws, 0);
			return NULL;
		}
		if (*val == '\\' || *val == '$') {
			if (val[1] >= 0 && val[1] <= '9') {
				int n = val[1] - '0';
				if (n < matchcount) {
					size_t len;

					len = matches[n].rm_eo -
						  matches[n].rm_so;

					if (len > u) {
						WS_Release(sp->wrk->ws, 0);
						return NULL;
					}

					memcpy(p, str + matches[n].rm_so, len);

					p += len;
					u -= len;
					val += 2;
					continue;
				}
			} else if (*val == '\\' && val[1]) {
				*p++ = val[1];
				u--;
				val += 2;
				continue;
			}
		}

		*p++ = *val++;
		u--;
	}

	if (qry) {
		size_t len = strlen(qry);
		if (len + 1 >= u)  {
			WS_Release(sp->wrk->ws, 0);
			return NULL;
		}
		if (strchr(b, '?'))
			*p++ = '&';
		else
			*p++ = '?';
		memcpy(p, qry, len);
		p += len;
		u -= len;
	}
	
	if (u == 0) {
		WS_Release(sp->wrk->ws, 0);
		return NULL;
	}
	*p = 0;
	
	WS_ReleaseP(sp->wrk->ws, p);

	return b;
}

static regmatch_t *matches;   /* Match map */
static size_t matchsize;      /* Total number of entries in matches */

#define ISEMPTY(s) ((s) == NULL || (s)[0] == 0)

static char *
findmatch(struct sess *sp, struct dbrw_connection *conn, char **param)
{
	unsigned i;
	unsigned nt, nf;
	char *res;
	struct wordsplit ws;
	int wsflags = WRDSF_NOCMD | WRDSF_QUOTE |
		      WRDSF_NOSPLIT |
		      WRDSF_ENV | WRDSF_UNDEF;
	
	if ((nt = sql_num_tuples(conn)) == 0 ||
	    (nf = sql_num_fields(conn)) == 0)
		return NULL;

	debug(conn->conf, 2, ("query returned %u tuples, %u columns", nt, nf));
	
	if (nf < 3)
		return WS_Dup(sp->ws, sql_get_column(conn, 0, 0));

	/* Three or four fields:
	     result
	     pattern
	     value
	     [flags]
	*/	     
	ws.ws_env = (const char **)param;
	res = NULL;
	for (i = 0; i < nt; i++) {
		const char *pat = sql_get_column(conn, i, 1);
		const char *val = sql_get_column(conn, i, 2);
		regex_t re;
		int rc;
		size_t matchcount;     /* Number of used entries in matches */
		int rflags = conn->conf->regflags;
		char status[HTTP_STATUS_LEN+1];
		int qdisp = conn->conf->qdisp;
		char *qry = NULL;

		if (ISEMPTY(pat)) {
			res = WS_Dup(sp->ws, sql_get_column(conn, i, 0));
			break;
		}
		
		debug(conn->conf, 1, ("considering \"%s\" ~ \"%s\"", pat, val));
		if (wordsplit(val, &ws, wsflags)) {
			dbrw_error("cannot expand string `%s': %s",
				      val, wordsplit_strerror(&ws));
			continue;
		}
		wsflags |= WRDSF_REUSE;

		val = ws.ws_wordv[0];
		debug(conn->conf, 1, ("expanded to \"%s\" ~ \"%s\"",
				      pat, val));

		strcpy(status, conn->conf->status);
		if (nf == 4) {
			if (parse_flags(sql_get_column(conn, i, 3),
					&qdisp, &rflags, status))
				continue;
		}
		
		switch (qdisp) {
		case QDISP_NONE:
			break;
		case QDISP_APPEND:
			qry = strchr(val, '?');
			if (qry)
				*qry++ = 0;
			break;
		case QDISP_DISCARD:
			qry = strchr(val, '?');
			if (qry) {
				debug(conn->conf, 1,
				      ("discarding query part \"%s\"", qry));
				*qry = 0;
				qry = NULL;
			}
		}
			
		rc = regcomp(&re, pat, rflags);
		if (rc) {
			char errbuf[512];

			regerror(rc, &re, errbuf, sizeof(errbuf));
			dbrw_error("cannot compile regexp \"%s\": %s",
				      pat, errbuf);
			continue;
		}

		matchcount = re.re_nsub + 1;
		if (matchsize < matchcount) {
			void *p = realloc(matches,
					  sizeof(matches[0]) * matchcount);
			if (!p) {
				dbrw_error("not enough memory");
				regfree(&re);
				continue;
			}
			matches = p;
			matchsize = matchcount;
		}

		rc = regexec(&re, val, matchcount, matches, 0);
		
		if (rc == 0)
			res = expand_backref(sp, val,
					     sql_get_column(conn, i, 0),
					     matchcount, matches, qry);

		regfree(&re);
		if (rc == 0) {
			debug(conn->conf, 1, ("match"));
			if (status[0]) {
				debug(conn->conf, 1,
				      ("setting status %s", status));
				VRT_SetHdr(sp, HDR_REQ,
					   "\023X-VMOD-DBRW-Status:",
					   status,
					   vrt_magic_string_end);
			}
			break;
		}
	}

	if (wsflags & WRDSF_REUSE)
		wordsplit_free(&ws);

	return res;
}

static struct dbrw_connection *
get_connection(struct dbrw_config *conf)
{
	struct dbrw_connection *cp = pthread_getspecific(thread_key);

	if (!cp) {
		cp = malloc(sizeof(*cp));
		if (!cp)
			return NULL;
		cp->state = state_init;
		cp->conf = conf;
		cp->data = NULL;

		if (sql_init(cp)) {
			free(cp);
			return NULL;
		}
		if (pthread_setspecific(thread_key, cp)) {
			dbrw_error("cannot set thread-specific data");
			sql_destroy(cp);
			free(cp);
			return NULL;
		}
	}
	return cp;
}

const char *
vmod_rewrite(struct sess *sp, struct vmod_priv *priv, const char *arg)
{
	struct dbrw_config *conf = priv->priv;
	struct dbrw_connection *cp;
	struct wordsplit ws, wsenv;
	int i, rc;
	char *res;

	debug(conf, 2, ("vmod_rewrite(%s) begin", arg));
	if (!conf || !conf->query) {
		debug(conf, 2, ("vmod_rewrite: not configured; exiting"));
		return NULL;
	}
	cp = get_connection(conf);
	if (!cp) {
		debug(conf, 2, ("vmod_rewrite: no private data; exiting"));
		return NULL;
	}
	
	if (sql_connect(cp) || cp->state != state_connected)
		return NULL;

	debug(conf, 2, ("vmod_rewrite: splitting arg"));
	wsenv.ws_delim = ";";
	if (wordsplit(arg, &wsenv, WRDSF_NOVAR|WRDSF_NOCMD|WRDSF_DELIM)) {
		dbrw_error("cannot split string `%s': %s",
			      arg, wordsplit_strerror(&wsenv));
		return NULL;
	}

	if (conf->backend->sql_escape) {
		debug(conf, 2, ("escaping variables"));
		for (i = 0; i < wsenv.ws_wordc; i++) {
			char *p = sql_escape(cp, wsenv.ws_wordv[i]);
			if (!p) {
				dbrw_error("cannot expand argument");
				wordsplit_free(&wsenv);
				return NULL;
			}
			free(wsenv.ws_wordv[i]);
			wsenv.ws_wordv[i] = p;
			debug(conf, 3, ("%d: %s",i,p));
		}
	}

	debug(conf, 2, ("expanding query"));
	ws.ws_env = (const char **)wsenv.ws_wordv;
	rc = wordsplit(conf->query, &ws,
		       WRDSF_NOCMD | WRDSF_QUOTE |
		       WRDSF_NOSPLIT |
		       WRDSF_ENV | WRDSF_UNDEF);
	if (rc) {
		dbrw_error("cannot expand query `%s': %s",
			      conf->query, wordsplit_strerror(&ws));
		wordsplit_free(&wsenv);
		return NULL;
	}

	rc = sql_query(cp, ws.ws_wordv[0]);
	wordsplit_free(&ws);

	if (rc) {
		debug(conf, 1, ("vmod_rewrite: query failed"));
		wordsplit_free(&wsenv);
		return NULL;
	}
	
	res = findmatch(sp, cp, wsenv.ws_wordv);
	wordsplit_free(&wsenv);

	sql_free_result(cp);

	debug(conf, 1, ("vmod_rewrite: res=%s", res ? res : "(NULL)"));
	
	return res;
}

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