kamailio/tcp_read.c

/*
 * $Id$
 *
 * Copyright (C) 2001-2003 FhG Fokus
 *
 * This file is part of ser, a free SIP server.
 *
 * ser 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 2 of the License, or
 * (at your option) any later version
 *
 * For a license to use the ser software under conditions
 * other than those described here, or to purchase support for this
 * software, please contact iptel.org by e-mail at the following addresses:
 *    [email protected]
 *
 * ser 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/*
 * History:
 * --------
 * 2002-12-??  created by andrei.
 * 2003-02-10  zero term before calling receive_msg & undo afterward (andrei)
 * 2003-05-13  l: (short form of Content-Length) is now recognized (andrei)
 * 2003-07-01  tcp_read & friends take no a single tcp_connection 
 *              parameter & they set c->state to S_CONN_EOF on eof (andrei)
 * 2003-07-04  fixed tcp EOF handling (possible infinite loop) (andrei)
 * 2005-07-05  migrated to the new io_wait code (andrei)
 * 2006-02-03  use tsend_stream instead of send_all (andrei)
 * 2006-10-13  added STUN support - state machine for TCP (vlada)
 * 2007-02-20  fixed timeout calc. bug (andrei)
 * 2007-11-26  improved tcp timers: switched to local_timer (andrei)
 * 2008-02-04  optimizations: handle POLLRDHUP (if supported), detect short
 *              reads (sock. buffer empty) (andrei)
 * 2009-02-26  direct blacklist support (andrei)
 * 2009-04-09  tcp ev and tcp stats macros added (andrei)
 */

#ifdef USE_TCP

#include <stdio.h>
#include <errno.h>
#include <string.h>


#include <sys/time.h>
#include <sys/types.h>
#include <sys/select.h>
#include <sys/socket.h>

#include <unistd.h>
#include <stdlib.h> /* for abort() */


#include "dprint.h"
#include "tcp_conn.h"
#include "tcp_stats.h"
#include "tcp_ev.h"
#include "pass_fd.h"
#include "globals.h"
#include "receive.h"
#include "timer.h"
#include "local_timer.h"
#include "ut.h"
#include "pt.h"
#include "cfg/cfg_struct.h"
#ifdef CORE_TLS
#include "tls/tls_server.h"
#else
#include "tls_hooks.h"
#endif /* CORE_TLS */
#ifdef USE_DST_BLACKLIST
#include "dst_blacklist.h"
#endif /* USE_DST_BLACKLIST */

#define HANDLE_IO_INLINE
#include "io_wait.h"
#include <fcntl.h> /* must be included after io_wait.h if SIGIO_RT is used */
#include "tsend.h"
#include "forward.h"

#ifdef USE_STUN
#include "ser_stun.h"

int is_msg_complete(struct tcp_req* r);

#endif /* USE_STUN */

#define TCPCONN_TIMEOUT_MIN_RUN  1 /* run the timers each new tick */

#define RD_CONN_SHORT_READ	1
#define RD_CONN_EOF		2
#define RD_CONN_FORCE_EOF	65536

/* types used in io_wait* */
enum fd_types { F_NONE, F_TCPMAIN, F_TCPCONN };

/* list of tcp connections handled by this process */
static struct tcp_connection* tcp_conn_lst=0;
static io_wait_h io_w; /* io_wait handler*/
static int tcpmain_sock=-1;

static struct local_timer tcp_reader_ltimer;
static ticks_t tcp_reader_prev_ticks;


/* reads next available bytes
 *   c- tcp connection used for reading, tcp_read changes also c->state on
 *      EOF and c->req.error on read error
 *   * flags - value/result - used to signal a seen or "forced" EOF on the 
 *     connection (when it is known that no more data will come after the 
 *     current socket buffer is emptied )=> return/signal EOF on the first 
 *     short read (=> don't use it on POLLPRI, as OOB data will cause short
 *      reads even if there are still remaining bytes in the socket buffer)
 * return number of bytes read, 0 on EOF or -1 on error,
 * on EOF it also sets c->state to S_CONN_EOF.
 * (to distinguish from reads that would block which could return 0)
 * RD_CONN_SHORT_READ is also set in *flags for short reads.
 * sets also r->error */
int tcp_read(struct tcp_connection *c, int* flags)
{
	int bytes_free, bytes_read;
	struct tcp_req *r;
	int fd;

	r=&c->req;
	fd=c->fd;
	bytes_free=r->b_size- (int)(r->pos - r->buf);
	
	if (bytes_free==0){
		LOG(L_ERR, "ERROR: tcp_read: buffer overrun, dropping\n");
		r->error=TCP_REQ_OVERRUN;
		return -1;
	}
again:
	bytes_read=read(fd, r->pos, bytes_free);

	if (likely(bytes_read!=bytes_free)){
		if(unlikely(bytes_read==-1)){
			if (errno == EWOULDBLOCK || errno == EAGAIN){
				bytes_read=0; /* nothing has been read */
			}else if (errno == EINTR) goto again;
			else{
				if (unlikely(c->state==S_CONN_CONNECT)){
					switch(errno){
						case ECONNRESET:
#ifdef USE_DST_BLACKLIST
							dst_blacklist_su(BLST_ERR_CONNECT, c->rcv.proto,
												&c->rcv.src_su,
												&c->send_flags, 0);
#endif /* USE_DST_BLACKLIST */
							TCP_EV_CONNECT_RST(errno, TCP_LADDR(c),
									TCP_LPORT(c), TCP_PSU(c), TCP_PROTO(c));
							break;
						case ETIMEDOUT:
#ifdef USE_DST_BLACKLIST
							dst_blacklist_su(BLST_ERR_CONNECT, c->rcv.proto,
												&c->rcv.src_su,
												&c->send_flags, 0);
#endif /* USE_DST_BLACKLIST */
							TCP_EV_CONNECT_TIMEOUT(errno, TCP_LADDR(c),
									TCP_LPORT(c), TCP_PSU(c), TCP_PROTO(c));
							break;
						default:
							TCP_EV_CONNECT_ERR(errno, TCP_LADDR(c),
									TCP_LPORT(c), TCP_PSU(c), TCP_PROTO(c));
					}
					TCP_STATS_CONNECT_FAILED();
				}else{
						switch(errno){
							case ECONNRESET:
								TCP_STATS_CON_RESET();
							case ETIMEDOUT:
#ifdef USE_DST_BLACKLIST
								dst_blacklist_su(BLST_ERR_SEND, c->rcv.proto,
													&c->rcv.src_su,
													&c->send_flags, 0);
#endif /* USE_DST_BLACKLIST */
								break;
						}
				}
				LOG(L_ERR, "ERROR: tcp_read: error reading: %s (%d)\n",
							strerror(errno), errno);
				r->error=TCP_READ_ERROR;
				return -1;
			}
		}else if (unlikely((bytes_read==0) || 
					(*flags & RD_CONN_FORCE_EOF))){
			c->state=S_CONN_EOF;
			*flags|=RD_CONN_EOF;
			DBG("tcp_read: EOF on %p, FD %d\n", c, fd);
		}else{
			if (unlikely(c->state==S_CONN_CONNECT || c->state==S_CONN_ACCEPT)){
				TCP_STATS_ESTABLISHED(c->state);
				c->state=S_CONN_OK;
			}
		}
		/* short read */
		*flags|=RD_CONN_SHORT_READ;
	}else{ /* else normal full read */
		if (unlikely(c->state==S_CONN_CONNECT || c->state==S_CONN_ACCEPT)){
			TCP_STATS_ESTABLISHED(c->state);
			c->state=S_CONN_OK;
		}
	}
#ifdef EXTRA_DEBUG
	DBG("tcp_read: read %d bytes:\n%.*s\n", bytes_read, bytes_read, r->pos);
#endif
	r->pos+=bytes_read;
	return bytes_read;
}



/* reads all headers (until double crlf), & parses the content-length header
 * (WARNING: inefficient, tries to reuse receive_msg but will go through
 * the headers twice [once here looking for Content-Length and for the end
 * of the headers and once in receive_msg]; a more speed efficient version will
 * result in either major code duplication or major changes to the receive code)
 * returns number of bytes read & sets r->state & r->body
 * when either r->body!=0 or r->state==H_BODY =>
 * all headers have been read. It should be called in a while loop.
 * returns < 0 if error or 0 if EOF */
int tcp_read_headers(struct tcp_connection *c, int* read_flags)
{
	int bytes, remaining;
	char *p;
	struct tcp_req* r;
	
#ifdef USE_STUN
	unsigned int mc;   /* magic cookie */
	unsigned short body_len;
#endif
	
	#define crlf_default_skip_case \
					case '\n': \
						r->state=H_LF; \
						break; \
					default: \
						r->state=H_SKIP
	
	#define content_len_beg_case \
					case ' ': \
					case '\t': \
						if (!TCP_REQ_HAS_CLEN(r)) r->state=H_STARTWS; \
						else r->state=H_SKIP; \
							/* not interested if we already found one */ \
						break; \
					case 'C': \
					case 'c': \
						if(!TCP_REQ_HAS_CLEN(r)) r->state=H_CONT_LEN1; \
						else r->state=H_SKIP; \
						break; \
					case 'l': \
					case 'L': \
						/* short form for Content-Length */ \
						if (!TCP_REQ_HAS_CLEN(r)) r->state=H_L_COLON; \
						else r->state=H_SKIP; \
						break
						
	#define change_state(upper, lower, newstate)\
					switch(*p){ \
						case upper: \
						case lower: \
							r->state=(newstate); break; \
						crlf_default_skip_case; \
					}
	
	#define change_state_case(state0, upper, lower, newstate)\
					case state0: \
							  change_state(upper, lower, newstate); \
							  p++; \
							  break


	r=&c->req;
	/* if we still have some unparsed part, parse it first, don't do the read*/
	if (unlikely(r->parsed<r->pos)){
		bytes=0;
	}else{
#ifdef USE_TLS
		if (unlikely(c->type==PROTO_TLS))
			bytes=tls_read(c); /* FIXME: read_flags support */
		else
#endif
			bytes=tcp_read(c, read_flags);
		if (bytes<=0) return bytes;
	}
	p=r->parsed;
	
	while(p<r->pos && r->error==TCP_REQ_OK){
		switch((unsigned char)r->state){
			case H_BODY: /* read the body*/
				remaining=r->pos-p;
				if (remaining>r->bytes_to_go) remaining=r->bytes_to_go;
				r->bytes_to_go-=remaining;
				p+=remaining;
				if (r->bytes_to_go==0){
					r->flags|=F_TCP_REQ_COMPLETE;
					goto skip;
				}
				break;
				
			case H_SKIP:
				/* find lf, we are in this state if we are not interested
				 * in anything till end of line*/
				p=q_memchr(p, '\n', r->pos-p);
				if (p){
					p++;
					r->state=H_LF;
				}else{
					p=r->pos;
				}
				break;
				
			case H_LF:
				/* terminate on LF CR LF or LF LF */
				switch (*p){
					case '\r':
						r->state=H_LFCR;
						break;
					case '\n':
						/* found LF LF */
						r->state=H_BODY;
						if (TCP_REQ_HAS_CLEN(r)){
							r->body=p+1;
							r->bytes_to_go=r->content_len;
							if (r->bytes_to_go==0){
								r->flags|=F_TCP_REQ_COMPLETE;
								p++;
								goto skip;
							}
						}else{
							DBG("tcp_read_headers: ERROR: no clen, p=%X\n",
									*p);
							r->error=TCP_REQ_BAD_LEN;
						}
						break;
					content_len_beg_case;
					default: 
						r->state=H_SKIP;
				}
				p++;
				break;
			case H_LFCR:
				if (*p=='\n'){
					/* found LF CR LF */
					r->state=H_BODY;
					if (TCP_REQ_HAS_CLEN(r)){
						r->body=p+1;
						r->bytes_to_go=r->content_len;
						if (r->bytes_to_go==0){
							r->flags|=F_TCP_REQ_COMPLETE;
							p++;
							goto skip;
						}
					}else{
						DBG("tcp_read_headers: ERROR: no clen, p=%X\n",
									*p);
						r->error=TCP_REQ_BAD_LEN;
					}
				}else r->state=H_SKIP;
				p++;
				break;
				
			case H_STARTWS:
				switch (*p){
					content_len_beg_case;
					crlf_default_skip_case;
				}
				p++;
				break;
			case H_SKIP_EMPTY:
				switch (*p){
					case '\n':
						break;
					case '\r':
						if (cfg_get(tcp, tcp_cfg, crlf_ping)) {
							r->state=H_SKIP_EMPTY_CR_FOUND;
							r->start=p;
						}
						break;
					case ' ':
					case '\t':
						/* skip empty lines */
						break;
					case 'C': 
					case 'c': 
						r->state=H_CONT_LEN1; 
						r->start=p;
						break;
					case 'l':
					case 'L':
						/* short form for Content-Length */
						r->state=H_L_COLON;
						r->start=p;
						break;
					default:
#ifdef USE_STUN
						/* STUN support can be switched off even if it's compiled */
						/* stun test */						
						if (stun_allow_stun && (unsigned char)*p == 0x00) {
							r->state=H_STUN_MSG;
						/* body will used as pointer to the last used byte */
							r->body=p;
							r->content_len = 0;
							DBG("stun msg detected\n");
						}else
#endif
						r->state=H_SKIP;
						r->start=p;
				};
				p++;
				break;

			case H_SKIP_EMPTY_CR_FOUND:
				if (*p=='\n'){
					r->state=H_SKIP_EMPTY_CRLF_FOUND;
					p++;
				}else{
					r->state=H_SKIP_EMPTY;
				}
				break;

			case H_SKIP_EMPTY_CRLF_FOUND:
				if (*p=='\r'){
					r->state = H_SKIP_EMPTY_CRLFCR_FOUND;
					p++;
				}else{
					r->state = H_SKIP_EMPTY;
				}
				break;

			case H_SKIP_EMPTY_CRLFCR_FOUND:
				if (*p=='\n'){
					r->state = H_PING_CRLF;
					r->flags |= F_TCP_REQ_HAS_CLEN |
							F_TCP_REQ_COMPLETE; /* hack to avoid error check */
					p++;
					goto skip;
				}else{
					r->state = H_SKIP_EMPTY;
				}
				break;
#ifdef USE_STUN
			case H_STUN_MSG:
				if ((r->pos - r->body) >= sizeof(struct stun_hdr)) {
					/* copy second short from buffer where should be body 
					 * length 
					 */
					memcpy(&body_len, &r->start[sizeof(unsigned short)], 
						sizeof(unsigned short));
					
					body_len = ntohs(body_len);
					
					/* check if there is valid magic cookie */
					memcpy(&mc, &r->start[sizeof(unsigned int)], 
						sizeof(unsigned int));
					mc = ntohl(mc);
					/* using has_content_len as a flag if there should be
					 * fingerprint or no
					 */
					r->flags |= (mc == MAGIC_COOKIE) ? F_TCP_REQ_HAS_CLEN : 0;
					
					r->body += sizeof(struct stun_hdr);
					p = r->body; 
					
					if (body_len > 0) {
						r->state = H_STUN_READ_BODY;
					}
					else {
						if (is_msg_complete(r) != 0) {
							goto skip;
						}
						else {
							/* set content_len to length of fingerprint */
							body_len = sizeof(struct stun_attr) + 
									   SHA_DIGEST_LENGTH;
						}
					}
					r->content_len=body_len;
				}
				else {
					p = r->pos; 
				}
				break;
				
			case H_STUN_READ_BODY:
				/* check if the whole body was read */
				body_len=r->content_len;
				if ((r->pos - r->body) >= body_len) {
					r->body += body_len;
					p = r->body;
					if (is_msg_complete(r) != 0) {
						r->content_len=0;
						goto skip;
					}
					else {
						/* set content_len to length of fingerprint */
						body_len = sizeof(struct stun_attr)+SHA_DIGEST_LENGTH;
						r->content_len=body_len;
					}
				}
				else {
					p = r->pos;
				}
				break;
				
			case H_STUN_FP:
				/* content_len contains length of fingerprint in this place! */
				body_len=r->content_len;
				if ((r->pos - r->body) >= body_len) {
					r->body += body_len;
					p = r->body;
					r->state = H_STUN_END;
					r->flags |= F_TCP_REQ_COMPLETE |
						F_TCP_REQ_HAS_CLEN; /* hack to avoid error check */
					r->content_len=0;
					goto skip;
				}
				else {
					p = r->pos;
				}
				break;
#endif /* USE_STUN */
			change_state_case(H_CONT_LEN1,  'O', 'o', H_CONT_LEN2);
			change_state_case(H_CONT_LEN2,  'N', 'n', H_CONT_LEN3);
			change_state_case(H_CONT_LEN3,  'T', 't', H_CONT_LEN4);
			change_state_case(H_CONT_LEN4,  'E', 'e', H_CONT_LEN5);
			change_state_case(H_CONT_LEN5,  'N', 'n', H_CONT_LEN6);
			change_state_case(H_CONT_LEN6,  'T', 't', H_CONT_LEN7);
			change_state_case(H_CONT_LEN7,  '-', '_', H_CONT_LEN8);
			change_state_case(H_CONT_LEN8,  'L', 'l', H_CONT_LEN9);
			change_state_case(H_CONT_LEN9,  'E', 'e', H_CONT_LEN10);
			change_state_case(H_CONT_LEN10, 'N', 'n', H_CONT_LEN11);
			change_state_case(H_CONT_LEN11, 'G', 'g', H_CONT_LEN12);
			change_state_case(H_CONT_LEN12, 'T', 't', H_CONT_LEN13);
			change_state_case(H_CONT_LEN13, 'H', 'h', H_L_COLON);
			
			case H_L_COLON:
				switch(*p){
					case ' ':
					case '\t':
						break; /* skip space */
					case ':':
						r->state=H_CONT_LEN_BODY;
						break;
					crlf_default_skip_case;
				};
				p++;
				break;
			
			case  H_CONT_LEN_BODY:
				switch(*p){
					case ' ':
					case '\t':
						break; /* eat space */
					case '0':
					case '1':
					case '2':
					case '3':
					case '4':
					case '5':
					case '6':
					case '7':
					case '8':
					case '9':
						r->state=H_CONT_LEN_BODY_PARSE;
						r->content_len=(*p-'0');
						break;
					/*FIXME: content length on different lines ! */
					crlf_default_skip_case;
				}
				p++;
				break;
				
			case H_CONT_LEN_BODY_PARSE:
				switch(*p){
					case '0':
					case '1':
					case '2':
					case '3':
					case '4':
					case '5':
					case '6':
					case '7':
					case '8':
					case '9':
						r->content_len=r->content_len*10+(*p-'0');
						break;
					case '\r':
					case ' ':
					case '\t': /* FIXME: check if line contains only WS */
						r->state=H_SKIP;
						r->flags|=F_TCP_REQ_HAS_CLEN;
						break;
					case '\n':
						/* end of line, parse successful */
						r->state=H_LF;
						r->flags|=F_TCP_REQ_HAS_CLEN;
						break;
					default:
						LOG(L_ERR, "ERROR: tcp_read_headers: bad "
								"Content-Length header value, unexpected "
								"char %c in state %d\n", *p, r->state);
						r->state=H_SKIP; /* try to find another?*/
				}
				p++;
				break;
			
			default:
				LOG(L_CRIT, "BUG: tcp_read_headers: unexpected state %d\n",
						r->state);
				abort();
		}
	}
skip:
	r->parsed=p;
	return bytes;
}



int tcp_read_req(struct tcp_connection* con, int* bytes_read, int* read_flags)
{
	int bytes;
	int total_bytes;
	int resp;
	long size;
	struct tcp_req* req;
	struct dest_info dst;
	int s;
	char c;
	int ret;
		
		bytes=-1;
		total_bytes=0;
		resp=CONN_RELEASE;
		s=con->fd;
		req=&con->req;
#ifdef USE_TLS
		if (con->type==PROTO_TLS){
			ret=tls_fix_read_conn(con);
			if (unlikely(ret<0)){
				resp=CONN_ERROR;
				goto end_req;
			}else if (unlikely(ret==0))
				goto end_req; /* not enough data */
		}
#endif

again:
		if (likely(req->error==TCP_REQ_OK)){
			bytes=tcp_read_headers(con, read_flags);
#ifdef EXTRA_DEBUG
						/* if timeout state=0; goto end__req; */
			DBG("read= %d bytes, parsed=%d, state=%d, error=%d\n",
					bytes, (int)(req->parsed-req->start), req->state,
					req->error );
			DBG("tcp_read_req: last char=0x%02X, parsed msg=\n%.*s\n",
					*(req->parsed-1), (int)(req->parsed-req->start),
					req->start);
#endif
			if (unlikely(bytes==-1)){
				LOG(L_ERR, "ERROR: tcp_read_req: error reading \n");
				resp=CONN_ERROR;
				goto end_req;
			}
			total_bytes+=bytes;
			/* eof check:
			 * is EOF if eof on fd and req.  not complete yet,
			 * if req. is complete we might have a second unparsed
			 * request after it, so postpone release_with_eof
			 */
			if (unlikely((con->state==S_CONN_EOF) && 
						(! TCP_REQ_COMPLETE(req)))) {
				DBG( "tcp_read_req: EOF\n");
				resp=CONN_EOF;
				goto end_req;
			}
		
		}
		if (unlikely(req->error!=TCP_REQ_OK)){
			LOG(L_ERR,"ERROR: tcp_read_req: bad request, state=%d, error=%d "
					  "buf:\n%.*s\nparsed:\n%.*s\n", req->state, req->error,
					  (int)(req->pos-req->buf), req->buf,
					  (int)(req->parsed-req->start), req->start);
			DBG("- received from: port %d\n", con->rcv.src_port);
			print_ip("- received from: ip ",&con->rcv.src_ip, "\n");
			resp=CONN_ERROR;
			goto end_req;
		}
		if (likely(TCP_REQ_COMPLETE(req))){
#ifdef EXTRA_DEBUG
			DBG("tcp_read_req: end of header part\n");
			DBG("- received from: port %d\n", con->rcv.src_port);
			print_ip("- received from: ip ", &con->rcv.src_ip, "\n");
			DBG("tcp_read_req: headers:\n%.*s.\n",
					(int)(req->body-req->start), req->start);
#endif
			if (likely(TCP_REQ_HAS_CLEN(req))){
				DBG("tcp_read_req: content-length= %d\n", req->content_len);
#ifdef EXTRA_DEBUG
				DBG("tcp_read_req: body:\n%.*s\n", req->content_len,req->body);
#endif
			}else{
				req->error=TCP_REQ_BAD_LEN;
				LOG(L_ERR, "ERROR: tcp_read_req: content length not present or"
						" unparsable\n");
				resp=CONN_ERROR;
				goto end_req;
			}
			/* if we are here everything is nice and ok*/
			resp=CONN_RELEASE;
#ifdef EXTRA_DEBUG
			DBG("calling receive_msg(%p, %d, )\n",
					req->start, (int)(req->parsed-req->start));
#endif
			/* rcv.bind_address should always be !=0 */
			bind_address=con->rcv.bind_address;
			/* just for debugging use sendipv4 as receiving socket  FIXME*/
			/*
			if (con->rcv.dst_ip.af==AF_INET6){
				bind_address=sendipv6_tcp;
			}else{
				bind_address=sendipv4_tcp;
			}
			*/
			con->rcv.proto_reserved1=con->id; /* copy the id */
			c=*req->parsed; /* ugly hack: zero term the msg & save the
							   previous char, req->parsed should be ok
							   because we always alloc BUF_SIZE+1 */
			*req->parsed=0;

			if (req->state==H_PING_CRLF) {
				init_dst_from_rcv(&dst, &con->rcv);

				if (tcp_send(&dst, 0, CRLF, CRLF_LEN) < 0) {
					LOG(L_ERR, "CRLF ping: tcp_send() failed\n");
				}
				ret = 0;
			}else
#ifdef USE_STUN
			if (unlikely(req->state==H_STUN_END)){
				/* stun request */
				ret = stun_process_msg(req->start, req->parsed-req->start,
									 &con->rcv);
			}else
#endif
				ret = receive_msg(req->start, req->parsed-req->start,
									&con->rcv);
				
			if (unlikely(ret < 0)) {
				*req->parsed=c;
				resp=CONN_ERROR;
				goto end_req;
			}
			*req->parsed=c;
			
			/* prepare for next request */
			size=req->pos-req->parsed;
			req->start=req->buf;
			req->body=0;
			req->error=TCP_REQ_OK;
			req->state=H_SKIP_EMPTY;
			req->flags=0;
			req->content_len=0;
			req->bytes_to_go=0;
			req->pos=req->buf+size;
			
			if (unlikely(size)){ 
				memmove(req->buf, req->parsed, size);
				req->parsed=req->buf; /* fix req->parsed after using it */
#ifdef EXTRA_DEBUG
				DBG("tcp_read_req: preparing for new request, kept %ld"
						" bytes\n", size);
#endif
				/*if we still have some unparsed bytes, try to parse them too*/
				goto again;
			} else if (unlikely(con->state==S_CONN_EOF)){
				DBG( "tcp_read_req: EOF after reading complete request\n");
				resp=CONN_EOF;
			}
			req->parsed=req->buf; /* fix req->parsed */
		}
		
		
	end_req:
		if (likely(bytes_read)) *bytes_read=total_bytes;
		return resp;
}



void release_tcpconn(struct tcp_connection* c, long state, int unix_sock)
{
	long response[2];
	
		DBG( "releasing con %p, state %ld, fd=%d, id=%d\n",
				c, state, c->fd, c->id);
		DBG(" extra_data %p\n", c->extra_data);
		/* release req & signal the parent */
		c->reader_pid=0; /* reset it */
		if (c->fd!=-1){
			close(c->fd);
			c->fd=-1;
		}
		/* errno==EINTR, EWOULDBLOCK a.s.o todo */
		response[0]=(long)c;
		response[1]=state;
		
		if (tsend_stream(unix_sock, (char*)response, sizeof(response), -1)<=0)
			LOG(L_ERR, "ERROR: release_tcpconn: tsend_stream failed\n");
}



static ticks_t tcpconn_read_timeout(ticks_t t, struct timer_ln* tl, void* data)
{
	struct tcp_connection *c;
	
	c=(struct tcp_connection*)data; 
	/* or (struct tcp...*)(tl-offset(c->timer)) */
	
	if (likely(!(c->state<0) && TICKS_LT(t, c->timeout))){
		/* timeout extended, exit */
		return (ticks_t)(c->timeout - t);
	}
	/* if conn->state is ERROR or BAD => force timeout too */
	if (unlikely(io_watch_del(&io_w, c->fd, -1, IO_FD_CLOSING)<0)){
		LOG(L_ERR, "ERROR: tcpconn_read_timeout: io_watch_del failed for %p"
					" id %d fd %d, state %d, flags %x, main fd %d\n",
					c, c->id, c->fd, c->state, c->flags, c->s);
	}
	tcpconn_listrm(tcp_conn_lst, c, c_next, c_prev);
	release_tcpconn(c, (c->state<0)?CONN_ERROR:CONN_RELEASE, tcpmain_sock);
	
	return 0;
}



/* handle io routine, based on the fd_map type
 * (it will be called from io_wait_loop* )
 * params:  fm  - pointer to a fd hash entry
 *          idx - index in the fd_array (or -1 if not known)
 * return: -1 on error, or when we are not interested any more on reads
 *            from this fd (e.g.: we are closing it )
 *          0 on EAGAIN or when by some other way it is known that no more 
 *            io events are queued on the fd (the receive buffer is empty).
 *            Usefull to detect when there are no more io events queued for
 *            sigio_rt, epoll_et, kqueue.
 *         >0 on successfull read from the fd (when there might be more io
 *            queued -- the receive buffer might still be non-empty)
 */
inline static int handle_io(struct fd_map* fm, short events, int idx)
{	
	int ret;
	int n;
	int read_flags;
	struct tcp_connection* con;
	int s;
	long resp;
	ticks_t t;
	
	/* update the local config */
	cfg_update();
	
	switch(fm->type){
		case F_TCPMAIN:
again:
			ret=n=receive_fd(fm->fd, &con, sizeof(con), &s, 0);
			DBG("received n=%d con=%p, fd=%d\n", n, con, s);
			if (unlikely(n<0)){
				if (errno == EWOULDBLOCK || errno == EAGAIN){
					ret=0;
					break;
				}else if (errno == EINTR) goto again;
				else{
					LOG(L_CRIT,"BUG: tcp_receive: handle_io: read_fd: %s \n",
							strerror(errno));
						abort(); /* big error*/
				}
			}
			if (unlikely(n==0)){
				LOG(L_ERR, "WARNING: tcp_receive: handle_io: 0 bytes read\n");
				goto error;
			}
			if (unlikely(con==0)){
					LOG(L_CRIT, "BUG: tcp_receive: handle_io null pointer\n");
					goto error;
			}
			con->fd=s;
			if (unlikely(s==-1)) {
				LOG(L_ERR, "ERROR: tcp_receive: handle_io: read_fd:"
									"no fd read\n");
				goto con_error;
			}
			con->reader_pid=my_pid();
			if (unlikely(con==tcp_conn_lst)){
				LOG(L_CRIT, "BUG: tcp_receive: handle_io: duplicate"
							" connection received: %p, id %d, fd %d, refcnt %d"
							" state %d (n=%d)\n", con, con->id, con->fd,
							atomic_get(&con->refcnt), con->state, n);
				goto con_error;
				break; /* try to recover */
			}
			if (unlikely(con->state==S_CONN_BAD)){
				LOG(L_WARN, "WARNING: tcp_receive: handle_io: received an"
							" already bad connection: %p id %d refcnt %d\n",
							con, con->id, atomic_get(&con->refcnt));
				goto con_error;
			}
			/* if we received the fd there is most likely data waiting to
			 * be read => process it first to avoid extra sys calls */
			read_flags=((con->flags & (F_CONN_EOF_SEEN|F_CONN_FORCE_EOF)) && 
						!(con->flags & F_CONN_OOB_DATA))? RD_CONN_FORCE_EOF
						:0;
			resp=tcp_read_req(con, &n, &read_flags);
			if (unlikely(resp<0)){
				/* some error occured, but on the new fd, not on the tcp
				 * main fd, so keep the ret value */
				if (unlikely(resp!=CONN_EOF))
					con->state=S_CONN_BAD;
				release_tcpconn(con, resp, tcpmain_sock);
				break;
			}
			
			/* must be before io_watch_add, io_watch_add might catch some
			 * already existing events => might call handle_io and
			 * handle_io might decide to del. the new connection =>
			 * must be in the list */
			tcpconn_listadd(tcp_conn_lst, con, c_next, c_prev);
			t=get_ticks_raw();
			con->timeout=t+S_TO_TICKS(TCP_CHILD_TIMEOUT);
			/* re-activate the timer */
			con->timer.f=tcpconn_read_timeout;
			local_timer_reinit(&con->timer);
			local_timer_add(&tcp_reader_ltimer, &con->timer,
								S_TO_TICKS(TCP_CHILD_TIMEOUT), t);
			if (unlikely(io_watch_add(&io_w, s, POLLIN, F_TCPCONN, con)<0)){
				LOG(L_CRIT, "ERROR: tcpconn_receive: handle_io: io_watch_add "
							"failed for %p id %d fd %d, state %d, flags %x,"
							" main fd %d, refcnt %d\n",
							con, con->id, con->fd, con->state, con->flags,
							con->s, atomic_get(&con->refcnt));
				tcpconn_listrm(tcp_conn_lst, con, c_next, c_prev);
				local_timer_del(&tcp_reader_ltimer, &con->timer);
				goto con_error;
			}
			break;
		case F_TCPCONN:
			con=(struct tcp_connection*)fm->data;
			if (unlikely(con->state==S_CONN_BAD)){
				resp=CONN_ERROR;
				if (!(con->send_flags.f & SND_F_CON_CLOSE))
					LOG(L_WARN, "WARNING: tcp_receive: handle_io: F_TCPCONN"
							" connection marked as bad: %p id %d refcnt %d\n",
							con, con->id, atomic_get(&con->refcnt));
				goto read_error;
			}
#ifdef POLLRDHUP
			read_flags=(((events & POLLRDHUP) | 
							(con->flags & (F_CONN_EOF_SEEN|F_CONN_FORCE_EOF)))
						&& !(events & POLLPRI))? RD_CONN_FORCE_EOF: 0;
#else /* POLLRDHUP */
			read_flags=0;
#endif /* POLLRDHUP */
			resp=tcp_read_req(con, &ret, &read_flags);
			if (unlikely(resp<0)){
read_error:
				ret=-1; /* some error occured */
				if (unlikely(io_watch_del(&io_w, con->fd, idx,
											IO_FD_CLOSING) < 0)){
					LOG(L_CRIT, "ERROR: tcpconn_receive: handle_io: "
							"io_watch_del failed for %p id %d fd %d,"
							" state %d, flags %x, main fd %d, refcnt %d\n",
							con, con->id, con->fd, con->state,
							con->flags, con->s, atomic_get(&con->refcnt));
				}
				tcpconn_listrm(tcp_conn_lst, con, c_next, c_prev);
				local_timer_del(&tcp_reader_ltimer, &con->timer);
				if (unlikely(resp!=CONN_EOF))
					con->state=S_CONN_BAD;
				release_tcpconn(con, resp, tcpmain_sock);
			}else{
				/* update timeout */
				con->timeout=get_ticks_raw()+S_TO_TICKS(TCP_CHILD_TIMEOUT);
				/* ret= 0 (read the whole socket buffer) if short read & 
				 *  !POLLPRI,  bytes read otherwise */
				ret&=(((read_flags & RD_CONN_SHORT_READ) && 
						!(events & POLLPRI)) - 1);
			}
			break;
		case F_NONE:
			LOG(L_CRIT, "BUG: handle_io: empty fd map %p (%d): "
						"{%d, %d, %p}\n", fm, (int)(fm-io_w.fd_hash),
						fm->fd, fm->type, fm->data);
			goto error;
		default:
			LOG(L_CRIT, "BUG: handle_io: uknown fd type %d\n", fm->type); 
			goto error;
	}
	
	return ret;
con_error:
	con->state=S_CONN_BAD;
	release_tcpconn(con, CONN_ERROR, tcpmain_sock);
	return ret;
error:
	return -1;
}



inline static void tcp_reader_timer_run()
{
	ticks_t ticks;
	
	ticks=get_ticks_raw();
	if (unlikely((ticks-tcp_reader_prev_ticks)<TCPCONN_TIMEOUT_MIN_RUN))
		return;
	tcp_reader_prev_ticks=ticks;
	local_timer_run(&tcp_reader_ltimer, ticks);
}



void tcp_receive_loop(int unix_sock)
{
	
	/* init */
	tcpmain_sock=unix_sock; /* init com. socket */
	if (init_io_wait(&io_w, get_max_open_fds(), tcp_poll_method)<0)
		goto error;
	tcp_reader_prev_ticks=get_ticks_raw();
	if (init_local_timer(&tcp_reader_ltimer, get_ticks_raw())!=0)
		goto error;
	/* add the unix socket */
	if (io_watch_add(&io_w, tcpmain_sock, POLLIN,  F_TCPMAIN, 0)<0){
		LOG(L_CRIT, "ERROR: tcp_receive_loop: init: failed to add socket "
							" to the fd list\n");
		goto error;
	}

	/* initialize the config framework */
	if (cfg_child_init()) goto error;

	/* main loop */
	switch(io_w.poll_method){
		case POLL_POLL:
				while(1){
					io_wait_loop_poll(&io_w, TCP_CHILD_SELECT_TIMEOUT, 0);
					tcp_reader_timer_run();
				}
				break;
#ifdef HAVE_SELECT
		case POLL_SELECT:
			while(1){
				io_wait_loop_select(&io_w, TCP_CHILD_SELECT_TIMEOUT, 0);
				tcp_reader_timer_run();
			}
			break;
#endif
#ifdef HAVE_SIGIO_RT
		case POLL_SIGIO_RT:
			while(1){
				io_wait_loop_sigio_rt(&io_w, TCP_CHILD_SELECT_TIMEOUT);
				tcp_reader_timer_run();
			}
			break;
#endif
#ifdef HAVE_EPOLL
		case POLL_EPOLL_LT:
			while(1){
				io_wait_loop_epoll(&io_w, TCP_CHILD_SELECT_TIMEOUT, 0);
				tcp_reader_timer_run();
			}
			break;
		case POLL_EPOLL_ET:
			while(1){
				io_wait_loop_epoll(&io_w, TCP_CHILD_SELECT_TIMEOUT, 1);
				tcp_reader_timer_run();
			}
			break;
#endif
#ifdef HAVE_KQUEUE
		case POLL_KQUEUE:
			while(1){
				io_wait_loop_kqueue(&io_w, TCP_CHILD_SELECT_TIMEOUT, 0);
				tcp_reader_timer_run();
			}
			break;
#endif
#ifdef HAVE_DEVPOLL
		case POLL_DEVPOLL:
			while(1){
				io_wait_loop_devpoll(&io_w, TCP_CHILD_SELECT_TIMEOUT, 0);
				tcp_reader_timer_run();
			}
			break;
#endif
		default:
			LOG(L_CRIT, "BUG: tcp_receive_loop: no support for poll method "
					" %s (%d)\n", 
					poll_method_name(io_w.poll_method), io_w.poll_method);
			goto error;
	}
error:
	destroy_io_wait(&io_w);
	LOG(L_CRIT, "ERROR: tcp_receive_loop: exiting...");
	exit(-1);
}



#ifdef USE_STUN
int is_msg_complete(struct tcp_req* r)
{
	if (TCP_REQ_HAS_CLEN(r)) {
		r->state = H_STUN_FP;
		return 0;
	}
	else {
		/* STUN message is complete */
		r->state = H_STUN_END;
		r->flags |= F_TCP_REQ_COMPLETE |
					F_TCP_REQ_HAS_CLEN; /* hack to avoid error check */
		return 1;
	}
}
#endif

#endif /* USE_TCP */