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 void sk_cleanup(void)
133 for (i = 0; (s = index234(sktree, i)) != NULL; i++) {
139 char *winsock_error_string(int error)
143 return "Network error: Permission denied";
145 return "Network error: Address already in use";
146 case WSAEADDRNOTAVAIL:
147 return "Network error: Cannot assign requested address";
148 case WSAEAFNOSUPPORT:
150 "Network error: Address family not supported by protocol family";
152 return "Network error: Operation already in progress";
153 case WSAECONNABORTED:
154 return "Network error: Software caused connection abort";
155 case WSAECONNREFUSED:
156 return "Network error: Connection refused";
158 return "Network error: Connection reset by peer";
159 case WSAEDESTADDRREQ:
160 return "Network error: Destination address required";
162 return "Network error: Bad address";
164 return "Network error: Host is down";
165 case WSAEHOSTUNREACH:
166 return "Network error: No route to host";
168 return "Network error: Operation now in progress";
170 return "Network error: Interrupted function call";
172 return "Network error: Invalid argument";
174 return "Network error: Socket is already connected";
176 return "Network error: Too many open files";
178 return "Network error: Message too long";
180 return "Network error: Network is down";
182 return "Network error: Network dropped connection on reset";
184 return "Network error: Network is unreachable";
186 return "Network error: No buffer space available";
188 return "Network error: Bad protocol option";
190 return "Network error: Socket is not connected";
192 return "Network error: Socket operation on non-socket";
194 return "Network error: Operation not supported";
195 case WSAEPFNOSUPPORT:
196 return "Network error: Protocol family not supported";
198 return "Network error: Too many processes";
199 case WSAEPROTONOSUPPORT:
200 return "Network error: Protocol not supported";
202 return "Network error: Protocol wrong type for socket";
204 return "Network error: Cannot send after socket shutdown";
205 case WSAESOCKTNOSUPPORT:
206 return "Network error: Socket type not supported";
208 return "Network error: Connection timed out";
210 return "Network error: Resource temporarily unavailable";
212 return "Network error: Graceful shutdown in progress";
214 return "Unknown network error";
218 SockAddr sk_namelookup(char *host, char **canonicalname)
220 SockAddr ret = smalloc(sizeof(struct SockAddr_tag));
222 struct hostent *h = NULL;
225 /* Clear the structure and default to IPv4. */
226 memset(ret, 0, sizeof(struct SockAddr_tag));
227 ret->family = 0; /* We set this one when we have resolved the host. */
230 if ((a = inet_addr(host)) == (unsigned long) INADDR_NONE) {
233 /* Try to get the getaddrinfo() function from wship6.dll */
234 /* This way one doesn't need to have IPv6 dll's to use PuTTY and
235 * it will fallback to IPv4. */
236 typedef int (CALLBACK * FGETADDRINFO) (const char *nodename,
237 const char *servname,
238 const struct addrinfo *
240 struct addrinfo ** res);
241 FGETADDRINFO fGetAddrInfo = NULL;
243 HINSTANCE dllWSHIP6 = LoadLibrary("wship6.dll");
245 fGetAddrInfo = (FGETADDRINFO) GetProcAddress(dllWSHIP6,
249 * Use fGetAddrInfo when it's available (which usually also
250 * means IPv6 is installed...)
253 /*debug(("Resolving \"%s\" with getaddrinfo() (IPv4+IPv6 capable)...\n", host)); */
254 if (fGetAddrInfo(host, NULL, NULL, &ret->ai) == 0)
255 ret->family = ret->ai->ai_family;
260 * Otherwise use the IPv4-only gethostbyname...
261 * (NOTE: we don't use gethostbyname as a
264 if (ret->family == 0) {
265 /*debug(("Resolving \"%s\" with gethostbyname() (IPv4 only)...\n", host)); */
266 if ( (h = gethostbyname(host)) )
267 ret->family = AF_INET;
270 /*debug(("Done resolving...(family is %d) AF_INET = %d, AF_INET6 = %d\n", ret->family, AF_INET, AF_INET6)); */
272 if (ret->family == 0) {
273 DWORD err = WSAGetLastError();
274 ret->error = (err == WSAENETDOWN ? "Network is down" :
276 WSAHOST_NOT_FOUND ? "Host does not exist" : err
277 == WSATRY_AGAIN ? "Host not found" :
279 fGetAddrInfo ? "getaddrinfo: unknown error" :
281 "gethostbyname: unknown error");
285 FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
286 FORMAT_MESSAGE_FROM_SYSTEM |
287 FORMAT_MESSAGE_IGNORE_INSERTS, NULL, err,
288 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
289 (LPTSTR) & lpMsgBuf, 0, NULL);
290 /*debug(("Error %ld: %s (h=%lx)\n", err, lpMsgBuf, h)); */
291 /* Free the buffer. */
299 /* If we got an address info use that... */
301 typedef int (CALLBACK * FGETNAMEINFO)
302 (const struct sockaddr FAR * sa, socklen_t salen,
303 char FAR * host, size_t hostlen, char FAR * serv,
304 size_t servlen, int flags);
305 FGETNAMEINFO fGetNameInfo = NULL;
307 /* Are we in IPv4 fallback mode? */
308 /* We put the IPv4 address into the a variable so we can further-on use the IPv4 code... */
309 if (ret->family == AF_INET)
311 (char *) &((SOCKADDR_IN *) ret->ai->
312 ai_addr)->sin_addr, sizeof(a));
314 /* Now let's find that canonicalname... */
317 (FGETNAMEINFO) GetProcAddress(dllWSHIP6,
320 ((struct sockaddr *) ret->ai->ai_addr,
322 AF_INET ? sizeof(SOCKADDR_IN) :
323 sizeof(SOCKADDR_IN6), realhost,
324 sizeof(realhost), NULL, 0, 0) != 0) {
325 strncpy(realhost, host, sizeof(realhost));
329 /* We used the IPv4-only gethostbyname()... */
333 memcpy(&a, h->h_addr, sizeof(a));
334 /* This way we are always sure the h->h_name is valid :) */
335 strncpy(realhost, h->h_name, sizeof(realhost));
339 FreeLibrary(dllWSHIP6);
343 * This must be a numeric IPv4 address because it caused a
344 * success return from inet_addr.
346 ret->family = AF_INET;
347 strncpy(realhost, host, sizeof(realhost));
349 ret->address = ntohl(a);
350 realhost[lenof(realhost)-1] = '\0';
351 *canonicalname = smalloc(1+strlen(realhost));
352 strcpy(*canonicalname, realhost);
356 void sk_getaddr(SockAddr addr, char *buf, int buflen)
359 if (addr->family == AF_INET) {
362 a.s_addr = htonl(addr->address);
363 strncpy(buf, inet_ntoa(a), buflen);
366 FIXME; /* I don't know how to get a text form of an IPv6 address. */
371 void sk_addr_free(SockAddr addr)
376 static Plug sk_tcp_plug(Socket sock, Plug p)
378 Actual_Socket s = (Actual_Socket) sock;
385 static void sk_tcp_flush(Socket s)
388 * We send data to the socket as soon as we can anyway,
389 * so we don't need to do anything here. :-)
393 static void sk_tcp_close(Socket s);
394 static int sk_tcp_write(Socket s, char *data, int len);
395 static int sk_tcp_write_oob(Socket s, char *data, int len);
396 static char *sk_tcp_socket_error(Socket s);
398 extern char *do_select(SOCKET skt, int startup);
400 Socket sk_register(void *sock, Plug plug)
402 static struct socket_function_table fn_table = {
416 * Create Socket structure.
418 ret = smalloc(sizeof(struct Socket_tag));
422 bufchain_init(&ret->output_data);
423 ret->writable = 1; /* to start with */
424 ret->sending_oob = 0;
426 ret->frozen_readable = 0;
427 ret->localhost_only = 0; /* unused, but best init anyway */
428 ret->pending_error = 0;
430 ret->s = (SOCKET)sock;
432 if (ret->s == INVALID_SOCKET) {
433 err = WSAGetLastError();
434 ret->error = winsock_error_string(err);
440 /* Set up a select mechanism. This could be an AsyncSelect on a
441 * window, or an EventSelect on an event object. */
442 errstr = do_select(ret->s, 1);
453 Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
454 int nodelay, Plug plug)
456 static struct socket_function_table fn_table = {
476 * Create Socket structure.
478 ret = smalloc(sizeof(struct Socket_tag));
482 bufchain_init(&ret->output_data);
483 ret->connected = 0; /* to start with */
484 ret->writable = 0; /* to start with */
485 ret->sending_oob = 0;
487 ret->frozen_readable = 0;
488 ret->localhost_only = 0; /* unused, but best init anyway */
489 ret->pending_error = 0;
494 s = socket(addr->family, SOCK_STREAM, 0);
497 if (s == INVALID_SOCKET) {
498 err = WSAGetLastError();
499 ret->error = winsock_error_string(err);
503 ret->oobinline = oobinline;
506 setsockopt(s, SOL_SOCKET, SO_OOBINLINE, (void *) &b, sizeof(b));
511 setsockopt(s, IPPROTO_TCP, TCP_NODELAY, (void *) &b, sizeof(b));
515 * Bind to local address.
518 localport = 1023; /* count from 1023 downwards */
520 localport = 0; /* just use port 0 (ie winsock picks) */
522 /* Loop round trying to bind */
527 if (addr->family == AF_INET6) {
528 memset(&a6, 0, sizeof(a6));
529 a6.sin6_family = AF_INET6;
530 /*a6.sin6_addr = in6addr_any; *//* == 0 */
531 a6.sin6_port = htons(localport);
535 a.sin_family = AF_INET;
536 a.sin_addr.s_addr = htonl(INADDR_ANY);
537 a.sin_port = htons(localport);
540 retcode = bind(s, (addr->family == AF_INET6 ?
541 (struct sockaddr *) &a6 :
542 (struct sockaddr *) &a),
544 AF_INET6 ? sizeof(a6) : sizeof(a)));
546 retcode = bind(s, (struct sockaddr *) &a, sizeof(a));
548 if (retcode != SOCKET_ERROR) {
552 err = WSAGetLastError();
553 if (err != WSAEADDRINUSE) /* failed, for a bad reason */
558 break; /* we're only looping once */
561 break; /* we might have got to the end */
565 ret->error = winsock_error_string(err);
570 * Connect to remote address.
573 if (addr->family == AF_INET6) {
574 memset(&a, 0, sizeof(a));
575 a6.sin6_family = AF_INET6;
576 a6.sin6_port = htons((short) port);
578 ((struct sockaddr_in6 *) addr->ai->ai_addr)->sin6_addr;
582 a.sin_family = AF_INET;
583 a.sin_addr.s_addr = htonl(addr->address);
584 a.sin_port = htons((short) port);
587 /* Set up a select mechanism. This could be an AsyncSelect on a
588 * window, or an EventSelect on an event object. */
589 errstr = do_select(s, 1);
597 connect(s, ((addr->family == AF_INET6) ?
598 (struct sockaddr *) &a6 : (struct sockaddr *) &a),
599 (addr->family == AF_INET6) ? sizeof(a6) : sizeof(a))
601 connect(s, (struct sockaddr *) &a, sizeof(a))
604 err = WSAGetLastError();
606 * We expect a potential EWOULDBLOCK here, because the
607 * chances are the front end has done a select for
608 * FD_CONNECT, so that connect() will complete
611 if ( err != WSAEWOULDBLOCK ) {
612 ret->error = winsock_error_string(err);
617 * If we _don't_ get EWOULDBLOCK, the connect has completed
618 * and we should set the socket as writable.
628 Socket sk_newlistener(int port, Plug plug, int local_host_only)
630 static struct socket_function_table fn_table = {
651 * Create Socket structure.
653 ret = smalloc(sizeof(struct Socket_tag));
657 bufchain_init(&ret->output_data);
658 ret->writable = 0; /* to start with */
659 ret->sending_oob = 0;
661 ret->frozen_readable = 0;
662 ret->localhost_only = local_host_only;
663 ret->pending_error = 0;
668 s = socket(AF_INET, SOCK_STREAM, 0);
671 if (s == INVALID_SOCKET) {
672 err = WSAGetLastError();
673 ret->error = winsock_error_string(err);
680 setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char *)&on, sizeof(on));
684 if (addr->family == AF_INET6) {
685 memset(&a6, 0, sizeof(a6));
686 a6.sin6_family = AF_INET6;
688 a6.sin6_addr = in6addr_loopback;
690 a6.sin6_addr = in6addr_any;
691 a6.sin6_port = htons(port);
695 a.sin_family = AF_INET;
697 a.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
699 a.sin_addr.s_addr = htonl(INADDR_ANY);
700 a.sin_port = htons((short)port);
703 retcode = bind(s, (addr->family == AF_INET6 ?
704 (struct sockaddr *) &a6 :
705 (struct sockaddr *) &a),
707 AF_INET6 ? sizeof(a6) : sizeof(a)));
709 retcode = bind(s, (struct sockaddr *) &a, sizeof(a));
711 if (retcode != SOCKET_ERROR) {
714 err = WSAGetLastError();
718 ret->error = winsock_error_string(err);
723 if (listen(s, SOMAXCONN) == SOCKET_ERROR) {
725 ret->error = winsock_error_string(err);
729 /* Set up a select mechanism. This could be an AsyncSelect on a
730 * window, or an EventSelect on an event object. */
731 errstr = do_select(s, 1);
742 static void sk_tcp_close(Socket sock)
744 extern char *do_select(SOCKET skt, int startup);
745 Actual_Socket s = (Actual_Socket) sock;
754 * The function which tries to send on a socket once it's deemed
757 void try_send(Actual_Socket s)
759 while (s->sending_oob || bufchain_size(&s->output_data) > 0) {
765 if (s->sending_oob) {
766 urgentflag = MSG_OOB;
767 len = s->sending_oob;
771 bufchain_prefix(&s->output_data, &data, &len);
773 nsent = send(s->s, data, len, urgentflag);
774 noise_ultralight(nsent);
776 err = (nsent < 0 ? WSAGetLastError() : 0);
777 if ((err < WSABASEERR && nsent < 0) || err == WSAEWOULDBLOCK) {
779 * Perfectly normal: we've sent all we can for the moment.
781 * (Some WinSock send() implementations can return
782 * <0 but leave no sensible error indication -
783 * WSAGetLastError() is called but returns zero or
784 * a small number - so we check that case and treat
785 * it just like WSAEWOULDBLOCK.)
789 } else if (nsent == 0 ||
790 err == WSAECONNABORTED || err == WSAECONNRESET) {
792 * If send() returns CONNABORTED or CONNRESET, we
793 * unfortunately can't just call plug_closing(),
794 * because it's quite likely that we're currently
795 * _in_ a call from the code we'd be calling back
796 * to, so we'd have to make half the SSH code
797 * reentrant. Instead we flag a pending error on
798 * the socket, to be dealt with (by calling
799 * plug_closing()) at some suitable future moment.
801 s->pending_error = err;
804 fatalbox(winsock_error_string(err));
807 if (s->sending_oob) {
809 memmove(s->oobdata, s->oobdata+nsent, len-nsent);
810 s->sending_oob = len - nsent;
815 bufchain_consume(&s->output_data, nsent);
821 static int sk_tcp_write(Socket sock, char *buf, int len)
823 Actual_Socket s = (Actual_Socket) sock;
826 * Add the data to the buffer list on the socket.
828 bufchain_add(&s->output_data, buf, len);
831 * Now try sending from the start of the buffer list.
836 return bufchain_size(&s->output_data);
839 static int sk_tcp_write_oob(Socket sock, char *buf, int len)
841 Actual_Socket s = (Actual_Socket) sock;
844 * Replace the buffer list on the socket with the data.
846 bufchain_clear(&s->output_data);
847 assert(len <= sizeof(s->oobdata));
848 memcpy(s->oobdata, buf, len);
849 s->sending_oob = len;
852 * Now try sending from the start of the buffer list.
857 return s->sending_oob;
860 int select_result(WPARAM wParam, LPARAM lParam)
864 char buf[20480]; /* nice big buffer for plenty of speed */
868 /* wParam is the socket itself */
869 s = find234(sktree, (void *) wParam, cmpforsearch);
871 return 1; /* boggle */
873 if ((err = WSAGETSELECTERROR(lParam)) != 0) {
875 * An error has occurred on this socket. Pass it to the
878 return plug_closing(s->plug, winsock_error_string(err), err, 0);
881 noise_ultralight(lParam);
883 switch (WSAGETSELECTEVENT(lParam)) {
885 s->connected = s->writable = 1;
888 /* In the case the socket is still frozen, we don't even bother */
890 s->frozen_readable = 1;
895 * We have received data on the socket. For an oobinline
896 * socket, this might be data _before_ an urgent pointer,
897 * in which case we send it to the back end with type==1
898 * (data prior to urgent).
902 ioctlsocket(s->s, SIOCATMARK, &atmark);
904 * Avoid checking the return value from ioctlsocket(),
905 * on the grounds that some WinSock wrappers don't
906 * support it. If it does nothing, we get atmark==1,
907 * which is equivalent to `no OOB pending', so the
908 * effect will be to non-OOB-ify any OOB data.
913 ret = recv(s->s, buf, sizeof(buf), 0);
914 noise_ultralight(ret);
916 err = WSAGetLastError();
917 if (err == WSAEWOULDBLOCK) {
922 return plug_closing(s->plug, winsock_error_string(err), err,
924 } else if (0 == ret) {
925 return plug_closing(s->plug, NULL, 0, 0);
927 return plug_receive(s->plug, atmark ? 0 : 1, buf, ret);
932 * This will only happen on a non-oobinline socket. It
933 * indicates that we can immediately perform an OOB read
934 * and get back OOB data, which we will send to the back
935 * end with type==2 (urgent data).
937 ret = recv(s->s, buf, sizeof(buf), MSG_OOB);
938 noise_ultralight(ret);
940 fatalbox(ret == 0 ? "Internal networking trouble" :
941 winsock_error_string(WSAGetLastError()));
943 return plug_receive(s->plug, 2, buf, ret);
948 int bufsize_before, bufsize_after;
950 bufsize_before = s->sending_oob + bufchain_size(&s->output_data);
952 bufsize_after = s->sending_oob + bufchain_size(&s->output_data);
953 if (bufsize_after < bufsize_before)
954 plug_sent(s->plug, bufsize_after);
958 /* Signal a close on the socket. First read any outstanding data. */
961 ret = recv(s->s, buf, sizeof(buf), 0);
963 err = WSAGetLastError();
964 if (err == WSAEWOULDBLOCK)
966 return plug_closing(s->plug, winsock_error_string(err),
970 open &= plug_receive(s->plug, 0, buf, ret);
972 open &= plug_closing(s->plug, NULL, 0, 0);
978 struct sockaddr_in isa;
979 int addrlen = sizeof(struct sockaddr_in);
980 SOCKET t; /* socket of connection */
982 memset(&isa, 0, sizeof(struct sockaddr_in));
984 t = accept(s->s,(struct sockaddr *)&isa,&addrlen);
985 if (t == INVALID_SOCKET)
987 err = WSAGetLastError();
988 if (err == WSATRY_AGAIN)
992 if (s->localhost_only &&
993 ntohl(isa.sin_addr.s_addr) != INADDR_LOOPBACK) {
994 closesocket(t); /* dodgy WinSock let nonlocal through */
995 } else if (plug_accepting(s->plug, (void*)t)) {
996 closesocket(t); /* denied or error */
1005 * Deal with socket errors detected in try_send().
1007 void net_pending_errors(void)
1013 * This might be a fiddly business, because it's just possible
1014 * that handling a pending error on one socket might cause
1015 * others to be closed. (I can't think of any reason this might
1016 * happen in current SSH implementation, but to maintain
1017 * generality of this network layer I'll assume the worst.)
1019 * So what we'll do is search the socket list for _one_ socket
1020 * with a pending error, and then handle it, and then search
1021 * the list again _from the beginning_. Repeat until we make a
1022 * pass with no socket errors present. That way we are
1023 * protected against the socket list changing under our feet.
1027 for (i = 0; (s = index234(sktree, i)) != NULL; i++) {
1028 if (s->pending_error) {
1030 * An error has occurred on this socket. Pass it to the
1033 plug_closing(s->plug,
1034 winsock_error_string(s->pending_error),
1035 s->pending_error, 0);
1043 * Each socket abstraction contains a `void *' private field in
1044 * which the client can keep state.
1046 void sk_set_private_ptr(Socket sock, void *ptr)
1048 Actual_Socket s = (Actual_Socket) sock;
1049 s->private_ptr = ptr;
1052 void *sk_get_private_ptr(Socket sock)
1054 Actual_Socket s = (Actual_Socket) sock;
1055 return s->private_ptr;
1059 * Special error values are returned from sk_namelookup and sk_new
1060 * if there's a problem. These functions extract an error message,
1061 * or return NULL if there's no problem.
1063 char *sk_addr_error(SockAddr addr)
1067 static char *sk_tcp_socket_error(Socket sock)
1069 Actual_Socket s = (Actual_Socket) sock;
1073 void sk_set_frozen(Socket sock, int is_frozen)
1075 Actual_Socket s = (Actual_Socket) sock;
1076 if (s->frozen == is_frozen)
1078 s->frozen = is_frozen;
1079 if (!is_frozen && s->frozen_readable) {
1081 recv(s->s, &c, 1, MSG_PEEK);
1083 s->frozen_readable = 0;
1087 * For Plink: enumerate all sockets currently active.
1089 SOCKET first_socket(int *state)
1093 s = index234(sktree, (*state)++);
1094 return s ? s->s : INVALID_SOCKET;
1097 SOCKET next_socket(int *state)
1099 Actual_Socket s = index234(sktree, (*state)++);
1100 return s ? s->s : INVALID_SOCKET;