udp.c

一个Windows下的Linux专用虚拟机

      int lasterrno=errno;
      closesocket(so->s);
      so->s=-1;
#ifdef _WIN32
      WSASetLastError(lasterrno);
#else
      errno=lasterrno;
#endif
    } else {
      /* success, insert in queue */
      setsockopt(so->s,SOL_SOCKET,SO_RCVBUF,(char *)&max_rcvbuf_size,sizeof(int));
      so->so_expire = curtime + SO_EXPIRE;
      insque(so,&udb);
    }
  }
  return(so->s);
}

void
udp_detach(so)
	struct socket *so;
{
	closesocket(so->s);
	/* if (so->so_m) m_free(so->so_m);    done by sofree */

	sofree(so);
}

struct tos_t udptos[] = {
	{0, 53, IPTOS_LOWDELAY, 0},			/* DNS */
#ifdef EMULATE_TALK
	{517, 517, IPTOS_LOWDELAY, EMU_TALK},	/* talk */
	{518, 518, IPTOS_LOWDELAY, EMU_NTALK},	/* ntalk */
#endif
#ifdef EMULATE_CUSEEME
	{0, 7648, IPTOS_LOWDELAY, EMU_CUSEEME},	/* Cu-Seeme */
#endif
	{0, 0, 0, 0}
};

u_int8_t
udp_tos(so)
	struct socket *so;
{
	int i = 0;
	
	while(udptos[i].tos) {
		if ((udptos[i].fport && ntohs(so->so_fport) == udptos[i].fport) ||
		    (udptos[i].lport && ntohs(so->so_lport) == udptos[i].lport)) {
		    	so->so_emu = udptos[i].emu;
			return udptos[i].tos;
		}
		i++;
	}
	
	return 0;
}

#ifdef EMULATE_TALK
#include "talkd.h"
#endif

/*
 * Here, talk/ytalk/ntalk requests must be emulated
 */
void
udp_emu(so, m)
	struct socket *so;
	struct mbuf *m;
{
#if defined(EMULATE_TALK) || defined(EMULATE_CUSEEME)
	struct sockaddr_in addr;
        int addrlen = sizeof(addr);
#endif
#ifdef EMULATE_TALK
	CTL_MSG_OLD *omsg;
	CTL_MSG *nmsg;
	char buff[sizeof(CTL_MSG)];
	u_char type;
	
struct talk_request {
	struct talk_request *next;
	struct socket *udp_so;
	struct socket *tcp_so;
} *req;
	
	static struct talk_request *req_tbl = 0;	
#endif

#ifdef EMULATE_TALK
struct cu_header {
	uint16_t	d_family;		// destination family
	uint16_t	d_port;			// destination port
	uint32_t	d_addr;			// destination address
	uint16_t	s_family;		// source family
	uint16_t	s_port;			// source port
	uint32_t	so_addr;		// source address
	uint32_t	seqn;			// sequence number
	uint16_t	message;		// message
	uint16_t	data_type;		// data type
	uint16_t	pkt_len;		// packet length
} *cu_head;
#endif

	switch(so->so_emu) {

#ifdef EMULATE_TALK
	 case EMU_TALK:
	 case EMU_NTALK:
		/*
		 * Talk emulation. We always change the ctl_addr to get
		 * some answers from the daemon. When an ANNOUNCE comes,
		 * we send LEAVE_INVITE to the local daemons. Also when a
		 * DELETE comes, we send copies to the local daemons.
		 */
		if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
			return;
		
#define	IS_OLD	(so->so_emu == EMU_TALK)

#define COPY_MSG(dest, src) { dest->type = src->type; \
			      dest->id_num = src->id_num; \
			      dest->pid = src->pid; \
			      dest->addr = src->addr; \
			      dest->ctl_addr = src->ctl_addr; \
			      memcpy(&dest->l_name, &src->l_name, NAME_SIZE_OLD); \
			      memcpy(&dest->r_name, &src->r_name, NAME_SIZE_OLD); \
	         	      memcpy(&dest->r_tty, &src->r_tty, TTY_SIZE); }

#define OTOSIN(ptr, field) ((struct sockaddr_in *)&ptr->field)
/* old_sockaddr to sockaddr_in */


		if (IS_OLD) {  		/* old talk */
			omsg = mtod(m, CTL_MSG_OLD*);
			nmsg = (CTL_MSG *) buff;
			type = omsg->type;
			OTOSIN(omsg, ctl_addr)->sin_port = addr.sin_port;
			OTOSIN(omsg, ctl_addr)->sin_addr = our_addr;
			strncpy(omsg->l_name, getlogin(), NAME_SIZE_OLD);
		} else {		/* new talk */	
			omsg = (CTL_MSG_OLD *) buff;
			nmsg = mtod(m, CTL_MSG *);
			type = nmsg->type;
			OTOSIN(nmsg, ctl_addr)->sin_port = addr.sin_port;
			OTOSIN(nmsg, ctl_addr)->sin_addr = our_addr;
			strncpy(nmsg->l_name, getlogin(), NAME_SIZE_OLD);
		}
		
		if (type == LOOK_UP) 
			return;		/* for LOOK_UP this is enough */
			
		if (IS_OLD) {		/* make a copy of the message */
			COPY_MSG(nmsg, omsg);
			nmsg->vers = 1;
			nmsg->answer = 0;
		} else
			COPY_MSG(omsg, nmsg);

		/*
		 * If if is an ANNOUNCE message, we go through the
		 * request table to see if a tcp port has already
		 * been redirected for this socket. If not, we solisten()
		 * a new socket and add this entry to the table.
		 * The port number of the tcp socket and our IP
		 * are put to the addr field of the message structures.
		 * Then a LEAVE_INVITE is sent to both local daemon
		 * ports, 517 and 518. This is why we have two copies
		 * of the message, one in old talk and one in new talk
		 * format.
		 */ 

		if (type == ANNOUNCE) {
			int s;
			u_short temp_port;
			
			for(req = req_tbl; req; req = req->next)
				if (so == req->udp_so)
					break;  	/* found it */
					
			if (!req) {	/* no entry for so, create new */
				req = (struct talk_request *)
					malloc(sizeof(struct talk_request));
				req->udp_so = so;
				req->tcp_so = solisten(0,		
					OTOSIN(omsg, addr)->sin_addr.s_addr,	
					OTOSIN(omsg, addr)->sin_port,
					SS_FACCEPTONCE);
				req->next = req_tbl;
				req_tbl = req;
			}			
			
			/* replace port number in addr field */
			addrlen = sizeof(addr);
			getsockname(req->tcp_so->s, 
					(struct sockaddr *) &addr,
					&addrlen);		
			OTOSIN(omsg, addr)->sin_port = addr.sin_port;
			OTOSIN(omsg, addr)->sin_addr = our_addr;
			OTOSIN(nmsg, addr)->sin_port = addr.sin_port;
			OTOSIN(nmsg, addr)->sin_addr = our_addr;
			
			/* send LEAVE_INVITEs */
			temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
			OTOSIN(omsg, ctl_addr)->sin_port = 0;
			OTOSIN(nmsg, ctl_addr)->sin_port = 0;
			omsg->type = nmsg->type = LEAVE_INVITE;			
			
			s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
			addr.sin_addr = our_addr;
			addr.sin_family = AF_INET;
			addr.sin_port = htons(517);
			sendto(s, (char *)omsg, sizeof(*omsg), 0, 
				(struct sockaddr *)&addr, sizeof(addr));
			addr.sin_port = htons(518);
			sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
				(struct sockaddr *) &addr, sizeof(addr));
			closesocket(s) ;

			omsg->type = nmsg->type = ANNOUNCE; 
			OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
			OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;
		}
		
		/*	
		 * If it is a DELETE message, we send a copy to the
		 * local daemons. Then we delete the entry corresponding
		 * to our socket from the request table.
		 */
		
		if (type == DELETE) {
			struct talk_request *temp_req, *req_next;
			int s;
			u_short temp_port;
			
			temp_port = OTOSIN(omsg, ctl_addr)->sin_port;
			OTOSIN(omsg, ctl_addr)->sin_port = 0;
			OTOSIN(nmsg, ctl_addr)->sin_port = 0;
			
			s = socket(AF_INET, SOCK_DGRAM, IPPROTO_IP);
			addr.sin_addr = our_addr;
			addr.sin_family = AF_INET;
			addr.sin_port = htons(517);
			sendto(s, (char *)omsg, sizeof(*omsg), 0,
				(struct sockaddr *)&addr, sizeof(addr));
			addr.sin_port = htons(518);
			sendto(s, (char *)nmsg, sizeof(*nmsg), 0,
				(struct sockaddr *)&addr, sizeof(addr));
			closesocket(s);
			
			OTOSIN(omsg, ctl_addr)->sin_port = temp_port;
			OTOSIN(nmsg, ctl_addr)->sin_port = temp_port;

			/* delete table entry */
			if (so == req_tbl->udp_so) {
				temp_req = req_tbl;
				req_tbl = req_tbl->next;
				free(temp_req);
			} else {
				temp_req = req_tbl;
				for(req = req_tbl->next; req; req = req_next) {
					req_next = req->next;
					if (so == req->udp_so) {
						temp_req->next = req_next;
						free(req);
						break;
					} else {
						temp_req = req;
					}
				}
			}
		}
		
		return;		
#endif
		
#ifdef EMULATE_CUSEEME
	case EMU_CUSEEME:
	
		/*
		 * Cu-SeeMe emulation.
		 * Hopefully the packet is more that 16 bytes long. We don't
		 * do any other tests, just replace the address and port
		 * fields.
		 */ 
		if (m->m_len >= sizeof (*cu_head)) {
			if (getsockname(so->s, (struct sockaddr *)&addr, &addrlen) < 0)
				return;
			cu_head = mtod(m, struct cu_header *);
			cu_head->s_port = addr.sin_port;
			cu_head->so_addr = our_addr.s_addr;
		}
		
		return;
#endif
	}
}

struct socket *
udp_listen(port, laddr, lport, flags)
	u_int port;
	u_int32_t laddr;
	u_int lport;
	int flags;
{
	struct sockaddr_in addr;
	struct socket *so;
	socklen_t addrlen = sizeof(struct sockaddr_in), opt = 1;
	
	if ((so = socreate()) == NULL) {
		free(so);
		return NULL;
	}
	so->s = socket(AF_INET,SOCK_DGRAM,0);
	so->so_expire = curtime + SO_EXPIRE;
	insque(so,&udb);

	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = INADDR_ANY;
	addr.sin_port = port;

	if (bind(so->s,(struct sockaddr *)&addr, addrlen) < 0) {
		udp_detach(so);
		return NULL;
	}
	setsockopt(so->s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));
/*	setsockopt(so->s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int)); */
	setsockopt(so->s,SOL_SOCKET,SO_RCVBUF,(char *)&max_rcvbuf_size,sizeof(int));
	
	getsockname(so->s,(struct sockaddr *)&addr,&addrlen);
	so->so_fport = addr.sin_port;

	/* Translate connections from localhost to the alias hostname */
	if (is_localhost(addr.sin_addr))
	   so->so_faddr = alias_addr;
	else
	   so->so_faddr = addr.sin_addr;
	
	so->so_lport = lport;
	so->so_laddr.s_addr = laddr;
	if (flags != SS_FACCEPTONCE)
	   so->so_expire = 0;
	
	so->so_state = SS_ISFCONNECTED;
	
	return so;
}