2 * Windows networking abstraction.
4 * Due to this clean abstraction it was possible
5 * to easily implement IPv6 support :)
7 * IPv6 patch 1 (27 October 2000) Jeroen Massar <jeroen@unfix.org>
8 * - Preliminary hacked IPv6 support.
9 * - Connecting to IPv6 address (eg fec0:4242:4242:100:2d0:b7ff:fe8f:5d42) works.
10 * - Connecting to IPv6 hostname (eg heaven.ipv6.unfix.org) works.
11 * - Compiles as either IPv4 or IPv6.
13 * IPv6 patch 2 (29 October 2000) Jeroen Massar <jeroen@unfix.org>
14 * - When compiled as IPv6 it also allows connecting to IPv4 hosts.
15 * - Added some more documentation.
17 * IPv6 patch 3 (18 November 2000) Jeroen Massar <jeroen@unfix.org>
18 * - It now supports dynamically loading the IPv6 resolver dll's.
19 * This way we should be able to distribute one (1) binary
20 * which supports both IPv4 and IPv6.
21 * - getaddrinfo() and getnameinfo() are loaded dynamicaly if possible.
22 * - in6addr_any is defined in this file so we don't need to link to wship6.lib
23 * - The patch is now more unified so that we can still
24 * remove all IPv6 support by undef'ing IPV6.
25 * But where it fallsback to IPv4 it uses the IPv4 code which is already in place...
26 * - Canonical name resolving works.
28 * IPv6 patch 4 (07 January 2001) Jeroen Massar <jeroen@unfix.org>
29 * - patch against CVS of today, will be submitted to the bugs list
30 * as a 'cvs diff -u' on Simon's request...
35 * Define IPV6 to have IPv6 on-the-fly-loading support.
36 * This means that one doesn't have to have an IPv6 stack to use it.
37 * But if an IPv6 stack is found it is used with a fallback to IPv4.
53 #define DEFINE_PLUG_METHOD_MACROS
59 struct socket_function_table *fn;
60 /* the above variable absolutely *must* be the first in this structure */
68 int frozen; /* this causes readability notifications to be ignored */
69 int frozen_readable; /* this means we missed at least one readability
70 * notification while we were frozen */
71 int localhost_only; /* for listening sockets */
75 int pending_error; /* in case send() returns error */
79 * We used to typedef struct Socket_tag *Socket.
81 * Since we have made the networking abstraction slightly more
82 * abstract, Socket no longer means a tcp socket (it could mean
83 * an ssl socket). So now we must use Actual_Socket when we know
84 * we are talking about a tcp socket.
86 typedef struct Socket_tag *Actual_Socket;
90 /* address family this belongs to, AF_INET for IPv4, AF_INET6 for IPv6. */
92 unsigned long address; /* Address IPv4 style. */
94 struct addrinfo *ai; /* Address IPv6 style. */
98 static tree234 *sktree;
100 static int cmpfortree(void *av, void *bv)
102 Actual_Socket a = (Actual_Socket) av, b = (Actual_Socket) bv;
103 unsigned long as = (unsigned long) a->s, bs = (unsigned long) b->s;
111 static int cmpforsearch(void *av, void *bv)
113 Actual_Socket b = (Actual_Socket) bv;
114 unsigned long as = (unsigned long) av, bs = (unsigned long) b->s;
124 sktree = newtree234(cmpfortree);
127 char *winsock_error_string(int error)
131 return "Network error: Permission denied";
133 return "Network error: Address already in use";
134 case WSAEADDRNOTAVAIL:
135 return "Network error: Cannot assign requested address";
136 case WSAEAFNOSUPPORT:
138 "Network error: Address family not supported by protocol family";
140 return "Network error: Operation already in progress";
141 case WSAECONNABORTED:
142 return "Network error: Software caused connection abort";
143 case WSAECONNREFUSED:
144 return "Network error: Connection refused";
146 return "Network error: Connection reset by peer";
147 case WSAEDESTADDRREQ:
148 return "Network error: Destination address required";
150 return "Network error: Bad address";
152 return "Network error: Host is down";
153 case WSAEHOSTUNREACH:
154 return "Network error: No route to host";
156 return "Network error: Operation now in progress";
158 return "Network error: Interrupted function call";
160 return "Network error: Invalid argument";
162 return "Network error: Socket is already connected";
164 return "Network error: Too many open files";
166 return "Network error: Message too long";
168 return "Network error: Network is down";
170 return "Network error: Network dropped connection on reset";
172 return "Network error: Network is unreachable";
174 return "Network error: No buffer space available";
176 return "Network error: Bad protocol option";
178 return "Network error: Socket is not connected";
180 return "Network error: Socket operation on non-socket";
182 return "Network error: Operation not supported";
183 case WSAEPFNOSUPPORT:
184 return "Network error: Protocol family not supported";
186 return "Network error: Too many processes";
187 case WSAEPROTONOSUPPORT:
188 return "Network error: Protocol not supported";
190 return "Network error: Protocol wrong type for socket";
192 return "Network error: Cannot send after socket shutdown";
193 case WSAESOCKTNOSUPPORT:
194 return "Network error: Socket type not supported";
196 return "Network error: Connection timed out";
198 return "Network error: Resource temporarily unavailable";
200 return "Network error: Graceful shutdown in progress";
202 return "Unknown network error";
206 SockAddr sk_namelookup(char *host, char **canonicalname)
208 SockAddr ret = smalloc(sizeof(struct SockAddr_tag));
210 struct hostent *h = NULL;
213 /* Clear the structure and default to IPv4. */
214 memset(ret, 0, sizeof(struct SockAddr_tag));
215 ret->family = 0; /* We set this one when we have resolved the host. */
218 if ((a = inet_addr(host)) == (unsigned long) INADDR_NONE) {
221 /* Try to get the getaddrinfo() function from wship6.dll */
222 /* This way one doesn't need to have IPv6 dll's to use PuTTY and
223 * it will fallback to IPv4. */
224 typedef int (CALLBACK * FGETADDRINFO) (const char *nodename,
225 const char *servname,
226 const struct addrinfo *
228 struct addrinfo ** res);
229 FGETADDRINFO fGetAddrInfo = NULL;
231 HINSTANCE dllWSHIP6 = LoadLibrary("wship6.dll");
233 fGetAddrInfo = (FGETADDRINFO) GetProcAddress(dllWSHIP6,
237 * Use fGetAddrInfo when it's available (which usually also
238 * means IPv6 is installed...)
241 /*debug(("Resolving \"%s\" with getaddrinfo() (IPv4+IPv6 capable)...\n", host)); */
242 if (fGetAddrInfo(host, NULL, NULL, &ret->ai) == 0)
243 ret->family = ret->ai->ai_family;
248 * Otherwise use the IPv4-only gethostbyname...
249 * (NOTE: we don't use gethostbyname as a
252 if (ret->family == 0) {
253 /*debug(("Resolving \"%s\" with gethostbyname() (IPv4 only)...\n", host)); */
254 if ( (h = gethostbyname(host)) )
255 ret->family = AF_INET;
258 /*debug(("Done resolving...(family is %d) AF_INET = %d, AF_INET6 = %d\n", ret->family, AF_INET, AF_INET6)); */
260 if (ret->family == 0) {
261 DWORD err = WSAGetLastError();
262 ret->error = (err == WSAENETDOWN ? "Network is down" :
264 WSAHOST_NOT_FOUND ? "Host does not exist" : err
265 == WSATRY_AGAIN ? "Host not found" :
267 fGetAddrInfo ? "getaddrinfo: unknown error" :
269 "gethostbyname: unknown error");
273 FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
274 FORMAT_MESSAGE_FROM_SYSTEM |
275 FORMAT_MESSAGE_IGNORE_INSERTS, NULL, err,
276 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
277 (LPTSTR) & lpMsgBuf, 0, NULL);
278 /*debug(("Error %ld: %s (h=%lx)\n", err, lpMsgBuf, h)); */
279 /* Free the buffer. */
287 /* If we got an address info use that... */
289 typedef int (CALLBACK * FGETNAMEINFO)
290 (const struct sockaddr FAR * sa, socklen_t salen,
291 char FAR * host, size_t hostlen, char FAR * serv,
292 size_t servlen, int flags);
293 FGETNAMEINFO fGetNameInfo = NULL;
295 /* Are we in IPv4 fallback mode? */
296 /* We put the IPv4 address into the a variable so we can further-on use the IPv4 code... */
297 if (ret->family == AF_INET)
299 (char *) &((SOCKADDR_IN *) ret->ai->
300 ai_addr)->sin_addr, sizeof(a));
302 /* Now let's find that canonicalname... */
305 (FGETNAMEINFO) GetProcAddress(dllWSHIP6,
308 ((struct sockaddr *) ret->ai->ai_addr,
310 AF_INET ? sizeof(SOCKADDR_IN) :
311 sizeof(SOCKADDR_IN6), realhost,
312 sizeof(realhost), NULL, 0, 0) != 0) {
313 strncpy(realhost, host, sizeof(realhost));
317 /* We used the IPv4-only gethostbyname()... */
321 memcpy(&a, h->h_addr, sizeof(a));
322 /* This way we are always sure the h->h_name is valid :) */
323 strncpy(realhost, h->h_name, sizeof(realhost));
327 FreeLibrary(dllWSHIP6);
331 * This must be a numeric IPv4 address because it caused a
332 * success return from inet_addr.
334 ret->family = AF_INET;
335 strncpy(realhost, host, sizeof(realhost));
337 ret->address = ntohl(a);
338 realhost[lenof(realhost)-1] = '\0';
339 *canonicalname = smalloc(1+strlen(realhost));
340 strcpy(*canonicalname, realhost);
344 void sk_getaddr(SockAddr addr, char *buf, int buflen)
347 if (addr->family == AF_INET) {
350 a.s_addr = htonl(addr->address);
351 strncpy(buf, inet_ntoa(a), buflen);
354 FIXME; /* I don't know how to get a text form of an IPv6 address. */
359 void sk_addr_free(SockAddr addr)
364 static Plug sk_tcp_plug(Socket sock, Plug p)
366 Actual_Socket s = (Actual_Socket) sock;
373 static void sk_tcp_flush(Socket s)
376 * We send data to the socket as soon as we can anyway,
377 * so we don't need to do anything here. :-)
381 static void sk_tcp_close(Socket s);
382 static int sk_tcp_write(Socket s, char *data, int len);
383 static int sk_tcp_write_oob(Socket s, char *data, int len);
384 static char *sk_tcp_socket_error(Socket s);
386 extern char *do_select(SOCKET skt, int startup);
388 Socket sk_register(void *sock, Plug plug)
390 static struct socket_function_table fn_table = {
404 * Create Socket structure.
406 ret = smalloc(sizeof(struct Socket_tag));
410 bufchain_init(&ret->output_data);
411 ret->writable = 1; /* to start with */
412 ret->sending_oob = 0;
414 ret->frozen_readable = 0;
415 ret->localhost_only = 0; /* unused, but best init anyway */
416 ret->pending_error = 0;
418 ret->s = (SOCKET)sock;
420 if (ret->s == INVALID_SOCKET) {
421 err = WSAGetLastError();
422 ret->error = winsock_error_string(err);
428 /* Set up a select mechanism. This could be an AsyncSelect on a
429 * window, or an EventSelect on an event object. */
430 errstr = do_select(ret->s, 1);
441 Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
442 int nodelay, Plug plug)
444 static struct socket_function_table fn_table = {
464 * Create Socket structure.
466 ret = smalloc(sizeof(struct Socket_tag));
470 bufchain_init(&ret->output_data);
471 ret->connected = 0; /* to start with */
472 ret->writable = 0; /* to start with */
473 ret->sending_oob = 0;
475 ret->frozen_readable = 0;
476 ret->localhost_only = 0; /* unused, but best init anyway */
477 ret->pending_error = 0;
482 s = socket(addr->family, SOCK_STREAM, 0);
485 if (s == INVALID_SOCKET) {
486 err = WSAGetLastError();
487 ret->error = winsock_error_string(err);
491 ret->oobinline = oobinline;
494 setsockopt(s, SOL_SOCKET, SO_OOBINLINE, (void *) &b, sizeof(b));
499 setsockopt(s, IPPROTO_TCP, TCP_NODELAY, (void *) &b, sizeof(b));
503 * Bind to local address.
506 localport = 1023; /* count from 1023 downwards */
508 localport = 0; /* just use port 0 (ie winsock picks) */
510 /* Loop round trying to bind */
515 if (addr->family == AF_INET6) {
516 memset(&a6, 0, sizeof(a6));
517 a6.sin6_family = AF_INET6;
518 /*a6.sin6_addr = in6addr_any; *//* == 0 */
519 a6.sin6_port = htons(localport);
523 a.sin_family = AF_INET;
524 a.sin_addr.s_addr = htonl(INADDR_ANY);
525 a.sin_port = htons(localport);
528 retcode = bind(s, (addr->family == AF_INET6 ?
529 (struct sockaddr *) &a6 :
530 (struct sockaddr *) &a),
532 AF_INET6 ? sizeof(a6) : sizeof(a)));
534 retcode = bind(s, (struct sockaddr *) &a, sizeof(a));
536 if (retcode != SOCKET_ERROR) {
540 err = WSAGetLastError();
541 if (err != WSAEADDRINUSE) /* failed, for a bad reason */
546 break; /* we're only looping once */
549 break; /* we might have got to the end */
553 ret->error = winsock_error_string(err);
558 * Connect to remote address.
561 if (addr->family == AF_INET6) {
562 memset(&a, 0, sizeof(a));
563 a6.sin6_family = AF_INET6;
564 a6.sin6_port = htons((short) port);
566 ((struct sockaddr_in6 *) addr->ai->ai_addr)->sin6_addr;
570 a.sin_family = AF_INET;
571 a.sin_addr.s_addr = htonl(addr->address);
572 a.sin_port = htons((short) port);
575 /* Set up a select mechanism. This could be an AsyncSelect on a
576 * window, or an EventSelect on an event object. */
577 errstr = do_select(s, 1);
585 connect(s, ((addr->family == AF_INET6) ?
586 (struct sockaddr *) &a6 : (struct sockaddr *) &a),
587 (addr->family == AF_INET6) ? sizeof(a6) : sizeof(a))
589 connect(s, (struct sockaddr *) &a, sizeof(a))
592 err = WSAGetLastError();
594 * We expect a potential EWOULDBLOCK here, because the
595 * chances are the front end has done a select for
596 * FD_CONNECT, so that connect() will complete
599 if ( err != WSAEWOULDBLOCK ) {
600 ret->error = winsock_error_string(err);
605 * If we _don't_ get EWOULDBLOCK, the connect has completed
606 * and we should set the socket as writable.
616 Socket sk_newlistener(int port, Plug plug, int local_host_only)
618 static struct socket_function_table fn_table = {
639 * Create Socket structure.
641 ret = smalloc(sizeof(struct Socket_tag));
645 bufchain_init(&ret->output_data);
646 ret->writable = 0; /* to start with */
647 ret->sending_oob = 0;
649 ret->frozen_readable = 0;
650 ret->localhost_only = local_host_only;
651 ret->pending_error = 0;
656 s = socket(AF_INET, SOCK_STREAM, 0);
659 if (s == INVALID_SOCKET) {
660 err = WSAGetLastError();
661 ret->error = winsock_error_string(err);
668 setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char *)&on, sizeof(on));
672 if (addr->family == AF_INET6) {
673 memset(&a6, 0, sizeof(a6));
674 a6.sin6_family = AF_INET6;
676 a6.sin6_addr = in6addr_loopback;
678 a6.sin6_addr = in6addr_any;
679 a6.sin6_port = htons(port);
683 a.sin_family = AF_INET;
685 a.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
687 a.sin_addr.s_addr = htonl(INADDR_ANY);
688 a.sin_port = htons((short)port);
691 retcode = bind(s, (addr->family == AF_INET6 ?
692 (struct sockaddr *) &a6 :
693 (struct sockaddr *) &a),
695 AF_INET6 ? sizeof(a6) : sizeof(a)));
697 retcode = bind(s, (struct sockaddr *) &a, sizeof(a));
699 if (retcode != SOCKET_ERROR) {
702 err = WSAGetLastError();
706 ret->error = winsock_error_string(err);
711 if (listen(s, SOMAXCONN) == SOCKET_ERROR) {
713 ret->error = winsock_error_string(err);
717 /* Set up a select mechanism. This could be an AsyncSelect on a
718 * window, or an EventSelect on an event object. */
719 errstr = do_select(s, 1);
730 static void sk_tcp_close(Socket sock)
732 extern char *do_select(SOCKET skt, int startup);
733 Actual_Socket s = (Actual_Socket) sock;
742 * The function which tries to send on a socket once it's deemed
745 void try_send(Actual_Socket s)
747 while (s->sending_oob || bufchain_size(&s->output_data) > 0) {
753 if (s->sending_oob) {
754 urgentflag = MSG_OOB;
755 len = s->sending_oob;
759 bufchain_prefix(&s->output_data, &data, &len);
761 nsent = send(s->s, data, len, urgentflag);
762 noise_ultralight(nsent);
764 err = (nsent < 0 ? WSAGetLastError() : 0);
765 if ((err < WSABASEERR && nsent < 0) || err == WSAEWOULDBLOCK) {
767 * Perfectly normal: we've sent all we can for the moment.
769 * (Some WinSock send() implementations can return
770 * <0 but leave no sensible error indication -
771 * WSAGetLastError() is called but returns zero or
772 * a small number - so we check that case and treat
773 * it just like WSAEWOULDBLOCK.)
777 } else if (nsent == 0 ||
778 err == WSAECONNABORTED || err == WSAECONNRESET) {
780 * If send() returns CONNABORTED or CONNRESET, we
781 * unfortunately can't just call plug_closing(),
782 * because it's quite likely that we're currently
783 * _in_ a call from the code we'd be calling back
784 * to, so we'd have to make half the SSH code
785 * reentrant. Instead we flag a pending error on
786 * the socket, to be dealt with (by calling
787 * plug_closing()) at some suitable future moment.
789 s->pending_error = err;
792 fatalbox(winsock_error_string(err));
795 if (s->sending_oob) {
797 memmove(s->oobdata, s->oobdata+nsent, len-nsent);
798 s->sending_oob = len - nsent;
803 bufchain_consume(&s->output_data, nsent);
809 static int sk_tcp_write(Socket sock, char *buf, int len)
811 Actual_Socket s = (Actual_Socket) sock;
814 * Add the data to the buffer list on the socket.
816 bufchain_add(&s->output_data, buf, len);
819 * Now try sending from the start of the buffer list.
824 return bufchain_size(&s->output_data);
827 static int sk_tcp_write_oob(Socket sock, char *buf, int len)
829 Actual_Socket s = (Actual_Socket) sock;
832 * Replace the buffer list on the socket with the data.
834 bufchain_clear(&s->output_data);
835 assert(len <= sizeof(s->oobdata));
836 memcpy(s->oobdata, buf, len);
837 s->sending_oob = len;
840 * Now try sending from the start of the buffer list.
845 return s->sending_oob;
848 int select_result(WPARAM wParam, LPARAM lParam)
852 char buf[20480]; /* nice big buffer for plenty of speed */
856 /* wParam is the socket itself */
857 s = find234(sktree, (void *) wParam, cmpforsearch);
859 return 1; /* boggle */
861 if ((err = WSAGETSELECTERROR(lParam)) != 0) {
863 * An error has occurred on this socket. Pass it to the
866 return plug_closing(s->plug, winsock_error_string(err), err, 0);
869 noise_ultralight(lParam);
871 switch (WSAGETSELECTEVENT(lParam)) {
873 s->connected = s->writable = 1;
876 /* In the case the socket is still frozen, we don't even bother */
878 s->frozen_readable = 1;
883 * We have received data on the socket. For an oobinline
884 * socket, this might be data _before_ an urgent pointer,
885 * in which case we send it to the back end with type==1
886 * (data prior to urgent).
890 ioctlsocket(s->s, SIOCATMARK, &atmark);
892 * Avoid checking the return value from ioctlsocket(),
893 * on the grounds that some WinSock wrappers don't
894 * support it. If it does nothing, we get atmark==1,
895 * which is equivalent to `no OOB pending', so the
896 * effect will be to non-OOB-ify any OOB data.
901 ret = recv(s->s, buf, sizeof(buf), 0);
902 noise_ultralight(ret);
904 err = WSAGetLastError();
905 if (err == WSAEWOULDBLOCK) {
910 return plug_closing(s->plug, winsock_error_string(err), err,
912 } else if (0 == ret) {
913 return plug_closing(s->plug, NULL, 0, 0);
915 return plug_receive(s->plug, atmark ? 0 : 1, buf, ret);
920 * This will only happen on a non-oobinline socket. It
921 * indicates that we can immediately perform an OOB read
922 * and get back OOB data, which we will send to the back
923 * end with type==2 (urgent data).
925 ret = recv(s->s, buf, sizeof(buf), MSG_OOB);
926 noise_ultralight(ret);
928 fatalbox(ret == 0 ? "Internal networking trouble" :
929 winsock_error_string(WSAGetLastError()));
931 return plug_receive(s->plug, 2, buf, ret);
936 int bufsize_before, bufsize_after;
938 bufsize_before = s->sending_oob + bufchain_size(&s->output_data);
940 bufsize_after = s->sending_oob + bufchain_size(&s->output_data);
941 if (bufsize_after < bufsize_before)
942 plug_sent(s->plug, bufsize_after);
946 /* Signal a close on the socket. First read any outstanding data. */
949 ret = recv(s->s, buf, sizeof(buf), 0);
951 err = WSAGetLastError();
952 if (err == WSAEWOULDBLOCK)
954 return plug_closing(s->plug, winsock_error_string(err),
958 open &= plug_receive(s->plug, 0, buf, ret);
960 open &= plug_closing(s->plug, NULL, 0, 0);
966 struct sockaddr_in isa;
967 int addrlen = sizeof(struct sockaddr_in);
968 SOCKET t; /* socket of connection */
970 memset(&isa, 0, sizeof(struct sockaddr_in));
972 t = accept(s->s,(struct sockaddr *)&isa,&addrlen);
973 if (t == INVALID_SOCKET)
975 err = WSAGetLastError();
976 if (err == WSATRY_AGAIN)
980 if (s->localhost_only &&
981 ntohl(isa.sin_addr.s_addr) != INADDR_LOOPBACK) {
982 closesocket(t); /* dodgy WinSock let nonlocal through */
983 } else if (plug_accepting(s->plug, (void*)t)) {
984 closesocket(t); /* denied or error */
993 * Deal with socket errors detected in try_send().
995 void net_pending_errors(void)
1001 * This might be a fiddly business, because it's just possible
1002 * that handling a pending error on one socket might cause
1003 * others to be closed. (I can't think of any reason this might
1004 * happen in current SSH implementation, but to maintain
1005 * generality of this network layer I'll assume the worst.)
1007 * So what we'll do is search the socket list for _one_ socket
1008 * with a pending error, and then handle it, and then search
1009 * the list again _from the beginning_. Repeat until we make a
1010 * pass with no socket errors present. That way we are
1011 * protected against the socket list changing under our feet.
1015 for (i = 0; (s = index234(sktree, i)) != NULL; i++) {
1016 if (s->pending_error) {
1018 * An error has occurred on this socket. Pass it to the
1021 plug_closing(s->plug,
1022 winsock_error_string(s->pending_error),
1023 s->pending_error, 0);
1031 * Each socket abstraction contains a `void *' private field in
1032 * which the client can keep state.
1034 void sk_set_private_ptr(Socket sock, void *ptr)
1036 Actual_Socket s = (Actual_Socket) sock;
1037 s->private_ptr = ptr;
1040 void *sk_get_private_ptr(Socket sock)
1042 Actual_Socket s = (Actual_Socket) sock;
1043 return s->private_ptr;
1047 * Special error values are returned from sk_namelookup and sk_new
1048 * if there's a problem. These functions extract an error message,
1049 * or return NULL if there's no problem.
1051 char *sk_addr_error(SockAddr addr)
1055 static char *sk_tcp_socket_error(Socket sock)
1057 Actual_Socket s = (Actual_Socket) sock;
1061 void sk_set_frozen(Socket sock, int is_frozen)
1063 Actual_Socket s = (Actual_Socket) sock;
1064 if (s->frozen == is_frozen)
1066 s->frozen = is_frozen;
1067 if (!is_frozen && s->frozen_readable) {
1069 recv(s->s, &c, 1, MSG_PEEK);
1071 s->frozen_readable = 0;
1075 * For Plink: enumerate all sockets currently active.
1077 SOCKET first_socket(int *state)
1081 s = index234(sktree, (*state)++);
1082 return s ? s->s : INVALID_SOCKET;
1085 SOCKET next_socket(int *state)
1087 Actual_Socket s = index234(sktree, (*state)++);
1088 return s ? s->s : INVALID_SOCKET;