windows/winnet.c

   1 /*
   2  * Windows networking abstraction.
   3  *
   4  * For the IPv6 code in here I am indebted to Jeroen Massar and
   5  * unfix.org.
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <assert.h>
  11
  12 #define DEFINE_PLUG_METHOD_MACROS
  13 #include "putty.h"
  14 #include "network.h"
  15 #include "tree234.h"
  16
  17 #include <ws2tcpip.h>
  18
  19 #ifndef NO_IPV6
  20 const struct in6_addr in6addr_any = IN6ADDR_ANY_INIT;
  21 const struct in6_addr in6addr_loopback = IN6ADDR_LOOPBACK_INIT;
  22 #endif
  23
  24 #define ipv4_is_loopback(addr) \
  25         ((p_ntohl(addr.s_addr) & 0xFF000000L) == 0x7F000000L)
  26
  27 /*
  28  * We used to typedef struct Socket_tag *Socket.
  29  *
  30  * Since we have made the networking abstraction slightly more
  31  * abstract, Socket no longer means a tcp socket (it could mean
  32  * an ssl socket).  So now we must use Actual_Socket when we know
  33  * we are talking about a tcp socket.
  34  */
  35 typedef struct Socket_tag *Actual_Socket;
  36
  37 /*
  38  * Mutable state that goes with a SockAddr: stores information
  39  * about where in the list of candidate IP(v*) addresses we've
  40  * currently got to.
  41  */
  42 typedef struct SockAddrStep_tag SockAddrStep;
  43 struct SockAddrStep_tag {
  44 #ifndef NO_IPV6
  45     struct addrinfo *ai;               /* steps along addr->ais */
  46 #endif
  47     int curraddr;
  48 };
  49
  50 struct Socket_tag {
  51     const struct socket_function_table *fn;
  52     /* the above variable absolutely *must* be the first in this structure */
  53     char *error;
  54     SOCKET s;
  55     Plug plug;
  56     void *private_ptr;
  57     bufchain output_data;
  58     int connected;
  59     int writable;
  60     int frozen; /* this causes readability notifications to be ignored */
  61     int frozen_readable; /* this means we missed at least one readability
  62                           * notification while we were frozen */
  63     int localhost_only;                /* for listening sockets */
  64     char oobdata[1];
  65     int sending_oob;
  66     int oobinline, nodelay, keepalive, privport;
  67     SockAddr addr;
  68     SockAddrStep step;
  69     int port;
  70     int pending_error;                 /* in case send() returns error */
  71     /*
  72      * We sometimes need pairs of Socket structures to be linked:
  73      * if we are listening on the same IPv6 and v4 port, for
  74      * example. So here we define `parent' and `child' pointers to
  75      * track this link.
  76      */
  77     Actual_Socket parent, child;
  78 };
  79
  80 struct SockAddr_tag {
  81     int refcount;
  82     char *error;
  83     int resolved;
  84 #ifndef NO_IPV6
  85     struct addrinfo *ais;              /* Addresses IPv6 style. */
  86 #endif
  87     unsigned long *addresses;          /* Addresses IPv4 style. */
  88     int naddresses;
  89     char hostname[512];                /* Store an unresolved host name. */
  90 };
  91
  92 /*
  93  * Which address family this address belongs to. AF_INET for IPv4;
  94  * AF_INET6 for IPv6; AF_UNSPEC indicates that name resolution has
  95  * not been done and a simple host name is held in this SockAddr
  96  * structure.
  97  */
  98 #ifndef NO_IPV6
  99 #define SOCKADDR_FAMILY(addr, step) \
 100     (!(addr)->resolved ? AF_UNSPEC : \
 101      (step).ai ? (step).ai->ai_family : AF_INET)
 102 #else
 103 #define SOCKADDR_FAMILY(addr, step) \
 104     (!(addr)->resolved ? AF_UNSPEC : AF_INET)
 105 #endif
 106
 107 /*
 108  * Start a SockAddrStep structure to step through multiple
 109  * addresses.
 110  */
 111 #ifndef NO_IPV6
 112 #define START_STEP(addr, step) \
 113     ((step).ai = (addr)->ais, (step).curraddr = 0)
 114 #else
 115 #define START_STEP(addr, step) \
 116     ((step).curraddr = 0)
 117 #endif
 118
 119 static tree234 *sktree;
 120
 121 static int cmpfortree(void *av, void *bv)
 122 {
 123     Actual_Socket a = (Actual_Socket) av, b = (Actual_Socket) bv;
 124     unsigned long as = (unsigned long) a->s, bs = (unsigned long) b->s;
 125     if (as < bs)
 126         return -1;
 127     if (as > bs)
 128         return +1;
 129     if (a < b)
 130         return -1;
 131     if (a > b)
 132         return +1;
 133     return 0;
 134 }
 135
 136 static int cmpforsearch(void *av, void *bv)
 137 {
 138     Actual_Socket b = (Actual_Socket) bv;
 139     unsigned long as = (unsigned long) av, bs = (unsigned long) b->s;
 140     if (as < bs)
 141         return -1;
 142     if (as > bs)
 143         return +1;
 144     return 0;
 145 }
 146
 147 DECL_WINDOWS_FUNCTION(static, int, WSAStartup, (WORD, LPWSADATA));
 148 DECL_WINDOWS_FUNCTION(static, int, WSACleanup, (void));
 149 DECL_WINDOWS_FUNCTION(static, int, closesocket, (SOCKET));
 150 DECL_WINDOWS_FUNCTION(static, u_long, ntohl, (u_long));
 151 DECL_WINDOWS_FUNCTION(static, u_long, htonl, (u_long));
 152 DECL_WINDOWS_FUNCTION(static, u_short, htons, (u_short));
 153 DECL_WINDOWS_FUNCTION(static, u_short, ntohs, (u_short));
 154 DECL_WINDOWS_FUNCTION(static, int, gethostname, (char *, int));
 155 DECL_WINDOWS_FUNCTION(static, struct hostent FAR *, gethostbyname,
 156                       (const char FAR *));
 157 DECL_WINDOWS_FUNCTION(static, struct servent FAR *, getservbyname,
 158                       (const char FAR *, const char FAR *));
 159 DECL_WINDOWS_FUNCTION(static, unsigned long, inet_addr, (const char FAR *));
 160 DECL_WINDOWS_FUNCTION(static, char FAR *, inet_ntoa, (struct in_addr));
 161 DECL_WINDOWS_FUNCTION(static, int, connect,
 162                       (SOCKET, const struct sockaddr FAR *, int));
 163 DECL_WINDOWS_FUNCTION(static, int, bind,
 164                       (SOCKET, const struct sockaddr FAR *, int));
 165 DECL_WINDOWS_FUNCTION(static, int, setsockopt,
 166                       (SOCKET, int, int, const char FAR *, int));
 167 DECL_WINDOWS_FUNCTION(static, SOCKET, socket, (int, int, int));
 168 DECL_WINDOWS_FUNCTION(static, int, listen, (SOCKET, int));
 169 DECL_WINDOWS_FUNCTION(static, int, send, (SOCKET, const char FAR *, int, int));
 170 DECL_WINDOWS_FUNCTION(static, int, ioctlsocket,
 171                       (SOCKET, long, u_long FAR *));
 172 DECL_WINDOWS_FUNCTION(static, SOCKET, accept,
 173                       (SOCKET, struct sockaddr FAR *, int FAR *));
 174 DECL_WINDOWS_FUNCTION(static, int, recv, (SOCKET, char FAR *, int, int));
 175 DECL_WINDOWS_FUNCTION(static, int, WSAIoctl,
 176                       (SOCKET, DWORD, LPVOID, DWORD, LPVOID, DWORD,
 177                        LPDWORD, LPWSAOVERLAPPED,
 178                        LPWSAOVERLAPPED_COMPLETION_ROUTINE));
 179 #ifndef NO_IPV6
 180 DECL_WINDOWS_FUNCTION(static, int, getaddrinfo,
 181                       (const char *nodename, const char *servname,
 182                        const struct addrinfo *hints, struct addrinfo **res));
 183 DECL_WINDOWS_FUNCTION(static, void, freeaddrinfo, (struct addrinfo *res));
 184 DECL_WINDOWS_FUNCTION(static, int, getnameinfo,
 185                       (const struct sockaddr FAR * sa, socklen_t salen,
 186                        char FAR * host, size_t hostlen, char FAR * serv,
 187                        size_t servlen, int flags));
 188 DECL_WINDOWS_FUNCTION(static, char *, gai_strerror, (int ecode));
 189 DECL_WINDOWS_FUNCTION(static, int, WSAAddressToStringA,
 190                       (LPSOCKADDR, DWORD, LPWSAPROTOCOL_INFO,
 191                        LPSTR, LPDWORD));
 192 #endif
 193
 194 static HMODULE winsock_module = NULL;
 195 static WSADATA wsadata;
 196 #ifndef NO_IPV6
 197 static HMODULE winsock2_module = NULL;
 198 static HMODULE wship6_module = NULL;
 199 #endif
 200
 201 int sk_startup(int hi, int lo)
 202 {
 203     WORD winsock_ver;
 204
 205     winsock_ver = MAKEWORD(hi, lo);
 206
 207     if (p_WSAStartup(winsock_ver, &wsadata)) {
 208         return FALSE;
 209     }
 210
 211     if (LOBYTE(wsadata.wVersion) != LOBYTE(winsock_ver)) {
 212         return FALSE;
 213     }
 214
 215 #ifdef NET_SETUP_DIAGNOSTICS
 216     {
 217         char buf[80];
 218         sprintf(buf, "Using WinSock %d.%d", hi, lo);
 219         logevent(NULL, buf);
 220     }
 221 #endif
 222     return TRUE;
 223 }
 224
 225 void sk_init(void)
 226 {
 227 #ifndef NO_IPV6
 228     winsock2_module =
 229 #endif
 230         winsock_module = load_system32_dll("ws2_32.dll");
 231     if (!winsock_module) {
 232         winsock_module = load_system32_dll("wsock32.dll");
 233     }
 234     if (!winsock_module)
 235         fatalbox("Unable to load any WinSock library");
 236
 237 #ifndef NO_IPV6
 238     /* Check if we have getaddrinfo in Winsock */
 239     if (GetProcAddress(winsock_module, "getaddrinfo") != NULL) {
 240 #ifdef NET_SETUP_DIAGNOSTICS
 241         logevent(NULL, "Native WinSock IPv6 support detected");
 242 #endif
 243         GET_WINDOWS_FUNCTION(winsock_module, getaddrinfo);
 244         GET_WINDOWS_FUNCTION(winsock_module, freeaddrinfo);
 245         GET_WINDOWS_FUNCTION(winsock_module, getnameinfo);
 246         GET_WINDOWS_FUNCTION(winsock_module, gai_strerror);
 247     } else {
 248         /* Fall back to wship6.dll for Windows 2000 */
 249         wship6_module = load_system32_dll("wship6.dll");
 250         if (wship6_module) {
 251 #ifdef NET_SETUP_DIAGNOSTICS
 252             logevent(NULL, "WSH IPv6 support detected");
 253 #endif
 254             GET_WINDOWS_FUNCTION(wship6_module, getaddrinfo);
 255             GET_WINDOWS_FUNCTION(wship6_module, freeaddrinfo);
 256             GET_WINDOWS_FUNCTION(wship6_module, getnameinfo);
 257             GET_WINDOWS_FUNCTION(wship6_module, gai_strerror);
 258         } else {
 259 #ifdef NET_SETUP_DIAGNOSTICS
 260             logevent(NULL, "No IPv6 support detected");
 261 #endif
 262         }
 263     }
 264     GET_WINDOWS_FUNCTION(winsock2_module, WSAAddressToStringA);
 265 #else
 266 #ifdef NET_SETUP_DIAGNOSTICS
 267     logevent(NULL, "PuTTY was built without IPv6 support");
 268 #endif
 269 #endif
 270
 271     GET_WINDOWS_FUNCTION(winsock_module, WSAAsyncSelect);
 272     GET_WINDOWS_FUNCTION(winsock_module, WSAEventSelect);
 273     GET_WINDOWS_FUNCTION(winsock_module, select);
 274     GET_WINDOWS_FUNCTION(winsock_module, WSAGetLastError);
 275     GET_WINDOWS_FUNCTION(winsock_module, WSAEnumNetworkEvents);
 276     GET_WINDOWS_FUNCTION(winsock_module, WSAStartup);
 277     GET_WINDOWS_FUNCTION(winsock_module, WSACleanup);
 278     GET_WINDOWS_FUNCTION(winsock_module, closesocket);
 279     GET_WINDOWS_FUNCTION(winsock_module, ntohl);
 280     GET_WINDOWS_FUNCTION(winsock_module, htonl);
 281     GET_WINDOWS_FUNCTION(winsock_module, htons);
 282     GET_WINDOWS_FUNCTION(winsock_module, ntohs);
 283     GET_WINDOWS_FUNCTION(winsock_module, gethostname);
 284     GET_WINDOWS_FUNCTION(winsock_module, gethostbyname);
 285     GET_WINDOWS_FUNCTION(winsock_module, getservbyname);
 286     GET_WINDOWS_FUNCTION(winsock_module, inet_addr);
 287     GET_WINDOWS_FUNCTION(winsock_module, inet_ntoa);
 288     GET_WINDOWS_FUNCTION(winsock_module, connect);
 289     GET_WINDOWS_FUNCTION(winsock_module, bind);
 290     GET_WINDOWS_FUNCTION(winsock_module, setsockopt);
 291     GET_WINDOWS_FUNCTION(winsock_module, socket);
 292     GET_WINDOWS_FUNCTION(winsock_module, listen);
 293     GET_WINDOWS_FUNCTION(winsock_module, send);
 294     GET_WINDOWS_FUNCTION(winsock_module, ioctlsocket);
 295     GET_WINDOWS_FUNCTION(winsock_module, accept);
 296     GET_WINDOWS_FUNCTION(winsock_module, recv);
 297     GET_WINDOWS_FUNCTION(winsock_module, WSAIoctl);
 298
 299     /* Try to get the best WinSock version we can get */
 300     if (!sk_startup(2,2) &&
 301         !sk_startup(2,0) &&
 302         !sk_startup(1,1)) {
 303         fatalbox("Unable to initialise WinSock");
 304     }
 305
 306     sktree = newtree234(cmpfortree);
 307 }
 308
 309 void sk_cleanup(void)
 310 {
 311     Actual_Socket s;
 312     int i;
 313
 314     if (sktree) {
 315         for (i = 0; (s = index234(sktree, i)) != NULL; i++) {
 316             p_closesocket(s->s);
 317         }
 318         freetree234(sktree);
 319         sktree = NULL;
 320     }
 321
 322     if (p_WSACleanup)
 323         p_WSACleanup();
 324     if (winsock_module)
 325         FreeLibrary(winsock_module);
 326 #ifndef NO_IPV6
 327     if (wship6_module)
 328         FreeLibrary(wship6_module);
 329 #endif
 330 }
 331
 332 char *winsock_error_string(int error)
 333 {
 334     switch (error) {
 335       case WSAEACCES:
 336         return "Network error: Permission denied";
 337       case WSAEADDRINUSE:
 338         return "Network error: Address already in use";
 339       case WSAEADDRNOTAVAIL:
 340         return "Network error: Cannot assign requested address";
 341       case WSAEAFNOSUPPORT:
 342         return
 343             "Network error: Address family not supported by protocol family";
 344       case WSAEALREADY:
 345         return "Network error: Operation already in progress";
 346       case WSAECONNABORTED:
 347         return "Network error: Software caused connection abort";
 348       case WSAECONNREFUSED:
 349         return "Network error: Connection refused";
 350       case WSAECONNRESET:
 351         return "Network error: Connection reset by peer";
 352       case WSAEDESTADDRREQ:
 353         return "Network error: Destination address required";
 354       case WSAEFAULT:
 355         return "Network error: Bad address";
 356       case WSAEHOSTDOWN:
 357         return "Network error: Host is down";
 358       case WSAEHOSTUNREACH:
 359         return "Network error: No route to host";
 360       case WSAEINPROGRESS:
 361         return "Network error: Operation now in progress";
 362       case WSAEINTR:
 363         return "Network error: Interrupted function call";
 364       case WSAEINVAL:
 365         return "Network error: Invalid argument";
 366       case WSAEISCONN:
 367         return "Network error: Socket is already connected";
 368       case WSAEMFILE:
 369         return "Network error: Too many open files";
 370       case WSAEMSGSIZE:
 371         return "Network error: Message too long";
 372       case WSAENETDOWN:
 373         return "Network error: Network is down";
 374       case WSAENETRESET:
 375         return "Network error: Network dropped connection on reset";
 376       case WSAENETUNREACH:
 377         return "Network error: Network is unreachable";
 378       case WSAENOBUFS:
 379         return "Network error: No buffer space available";
 380       case WSAENOPROTOOPT:
 381         return "Network error: Bad protocol option";
 382       case WSAENOTCONN:
 383         return "Network error: Socket is not connected";
 384       case WSAENOTSOCK:
 385         return "Network error: Socket operation on non-socket";
 386       case WSAEOPNOTSUPP:
 387         return "Network error: Operation not supported";
 388       case WSAEPFNOSUPPORT:
 389         return "Network error: Protocol family not supported";
 390       case WSAEPROCLIM:
 391         return "Network error: Too many processes";
 392       case WSAEPROTONOSUPPORT:
 393         return "Network error: Protocol not supported";
 394       case WSAEPROTOTYPE:
 395         return "Network error: Protocol wrong type for socket";
 396       case WSAESHUTDOWN:
 397         return "Network error: Cannot send after socket shutdown";
 398       case WSAESOCKTNOSUPPORT:
 399         return "Network error: Socket type not supported";
 400       case WSAETIMEDOUT:
 401         return "Network error: Connection timed out";
 402       case WSAEWOULDBLOCK:
 403         return "Network error: Resource temporarily unavailable";
 404       case WSAEDISCON:
 405         return "Network error: Graceful shutdown in progress";
 406       default:
 407         return "Unknown network error";
 408     }
 409 }
 410
 411 SockAddr sk_namelookup(const char *host, char **canonicalname,
 412                        int address_family)
 413 {
 414     SockAddr ret = snew(struct SockAddr_tag);
 415     unsigned long a;
 416     char realhost[8192];
 417     int hint_family;
 418
 419     /* Default to IPv4. */
 420     hint_family = (address_family == ADDRTYPE_IPV4 ? AF_INET :
 421 #ifndef NO_IPV6
 422                    address_family == ADDRTYPE_IPV6 ? AF_INET6 :
 423 #endif
 424                    AF_UNSPEC);
 425
 426     /* Clear the structure and default to IPv4. */
 427     memset(ret, 0, sizeof(struct SockAddr_tag));
 428 #ifndef NO_IPV6
 429     ret->ais = NULL;
 430 #endif
 431     ret->addresses = NULL;
 432     ret->resolved = FALSE;
 433     ret->refcount = 1;
 434     *realhost = '\0';
 435
 436     if ((a = p_inet_addr(host)) == (unsigned long) INADDR_NONE) {
 437         struct hostent *h = NULL;
 438         int err;
 439 #ifndef NO_IPV6
 440         /*
 441          * Use getaddrinfo when it's available
 442          */
 443         if (p_getaddrinfo) {
 444             struct addrinfo hints;
 445 #ifdef NET_SETUP_DIAGNOSTICS
 446             logevent(NULL, "Using getaddrinfo() for resolving");
 447 #endif
 448             memset(&hints, 0, sizeof(hints));
 449             hints.ai_family = hint_family;
 450             hints.ai_flags = AI_CANONNAME;
 451             if ((err = p_getaddrinfo(host, NULL, &hints, &ret->ais)) == 0)
 452                 ret->resolved = TRUE;
 453         } else
 454 #endif
 455         {
 456 #ifdef NET_SETUP_DIAGNOSTICS
 457             logevent(NULL, "Using gethostbyname() for resolving");
 458 #endif
 459             /*
 460              * Otherwise use the IPv4-only gethostbyname...
 461              * (NOTE: we don't use gethostbyname as a fallback!)
 462              */
 463             if ( (h = p_gethostbyname(host)) )
 464                 ret->resolved = TRUE;
 465             else
 466                 err = p_WSAGetLastError();
 467         }
 468
 469         if (!ret->resolved) {
 470             ret->error = (err == WSAENETDOWN ? "Network is down" :
 471                           err == WSAHOST_NOT_FOUND ? "Host does not exist" :
 472                           err == WSATRY_AGAIN ? "Host not found" :
 473 #ifndef NO_IPV6
 474                           p_getaddrinfo&&p_gai_strerror ? p_gai_strerror(err) :
 475 #endif
 476                           "gethostbyname: unknown error");
 477         } else {
 478             ret->error = NULL;
 479
 480 #ifndef NO_IPV6
 481             /* If we got an address info use that... */
 482             if (ret->ais) {
 483                 /* Are we in IPv4 fallback mode? */
 484                 /* We put the IPv4 address into the a variable so we can further-on use the IPv4 code... */
 485                 if (ret->ais->ai_family == AF_INET)
 486                     memcpy(&a,
 487                            (char *) &((SOCKADDR_IN *) ret->ais->
 488                                       ai_addr)->sin_addr, sizeof(a));
 489
 490                 if (ret->ais->ai_canonname)
 491                     strncpy(realhost, ret->ais->ai_canonname, lenof(realhost));
 492                 else
 493                     strncpy(realhost, host, lenof(realhost));
 494             }
 495             /* We used the IPv4-only gethostbyname()... */
 496             else
 497 #endif
 498             {
 499                 int n;
 500                 for (n = 0; h->h_addr_list[n]; n++);
 501                 ret->addresses = snewn(n, unsigned long);
 502                 ret->naddresses = n;
 503                 for (n = 0; n < ret->naddresses; n++) {
 504                     memcpy(&a, h->h_addr_list[n], sizeof(a));
 505                     ret->addresses[n] = p_ntohl(a);
 506                 }
 507                 memcpy(&a, h->h_addr, sizeof(a));
 508                 /* This way we are always sure the h->h_name is valid :) */
 509                 strncpy(realhost, h->h_name, sizeof(realhost));
 510             }
 511         }
 512     } else {
 513         /*
 514          * This must be a numeric IPv4 address because it caused a
 515          * success return from inet_addr.
 516          */
 517         ret->addresses = snewn(1, unsigned long);
 518         ret->naddresses = 1;
 519         ret->addresses[0] = p_ntohl(a);
 520         ret->resolved = TRUE;
 521         strncpy(realhost, host, sizeof(realhost));
 522     }
 523     realhost[lenof(realhost)-1] = '\0';
 524     *canonicalname = snewn(1+strlen(realhost), char);
 525     strcpy(*canonicalname, realhost);
 526     return ret;
 527 }
 528
 529 SockAddr sk_nonamelookup(const char *host)
 530 {
 531     SockAddr ret = snew(struct SockAddr_tag);
 532     ret->error = NULL;
 533     ret->resolved = FALSE;
 534 #ifndef NO_IPV6
 535     ret->ais = NULL;
 536 #endif
 537     ret->addresses = NULL;
 538     ret->naddresses = 0;
 539     ret->refcount = 1;
 540     strncpy(ret->hostname, host, lenof(ret->hostname));
 541     ret->hostname[lenof(ret->hostname)-1] = '\0';
 542     return ret;
 543 }
 544
 545 int sk_nextaddr(SockAddr addr, SockAddrStep *step)
 546 {
 547 #ifndef NO_IPV6
 548     if (step->ai) {
 549         if (step->ai->ai_next) {
 550             step->ai = step->ai->ai_next;
 551             return TRUE;
 552         } else
 553             return FALSE;
 554     }
 555 #endif
 556     if (step->curraddr+1 < addr->naddresses) {
 557         step->curraddr++;
 558         return TRUE;
 559     } else {
 560         return FALSE;
 561     }
 562 }
 563
 564 void sk_getaddr(SockAddr addr, char *buf, int buflen)
 565 {
 566     SockAddrStep step;
 567     START_STEP(addr, step);
 568
 569 #ifndef NO_IPV6
 570     if (step.ai) {
 571         int err = 0;
 572         if (p_WSAAddressToStringA) {
 573             DWORD dwbuflen = buflen;
 574             err = p_WSAAddressToStringA(step.ai->ai_addr, step.ai->ai_addrlen,
 575                                         NULL, buf, &dwbuflen);
 576         } else
 577             err = -1;
 578         if (err) {
 579             strncpy(buf, addr->hostname, buflen);
 580             if (!buf[0])
 581                 strncpy(buf, "<unknown>", buflen);
 582             buf[buflen-1] = '\0';
 583         }
 584     } else
 585 #endif
 586     if (SOCKADDR_FAMILY(addr, step) == AF_INET) {
 587         struct in_addr a;
 588         assert(addr->addresses && step.curraddr < addr->naddresses);
 589         a.s_addr = p_htonl(addr->addresses[step.curraddr]);
 590         strncpy(buf, p_inet_ntoa(a), buflen);
 591         buf[buflen-1] = '\0';
 592     } else {
 593         strncpy(buf, addr->hostname, buflen);
 594         buf[buflen-1] = '\0';
 595     }
 596 }
 597
 598 int sk_hostname_is_local(char *name)
 599 {
 600     return !strcmp(name, "localhost") ||
 601            !strcmp(name, "::1") ||
 602            !strncmp(name, "127.", 4);
 603 }
 604
 605 static INTERFACE_INFO local_interfaces[16];
 606 static int n_local_interfaces;       /* 0=not yet, -1=failed, >0=number */
 607
 608 static int ipv4_is_local_addr(struct in_addr addr)
 609 {
 610     if (ipv4_is_loopback(addr))
 611         return 1;                      /* loopback addresses are local */
 612     if (!n_local_interfaces) {
 613         SOCKET s = p_socket(AF_INET, SOCK_DGRAM, 0);
 614         DWORD retbytes;
 615
 616         if (p_WSAIoctl &&
 617             p_WSAIoctl(s, SIO_GET_INTERFACE_LIST, NULL, 0,
 618                        local_interfaces, sizeof(local_interfaces),
 619                        &retbytes, NULL, NULL) == 0)
 620             n_local_interfaces = retbytes / sizeof(INTERFACE_INFO);
 621         else
 622             logevent(NULL, "Unable to get list of local IP addresses");
 623     }
 624     if (n_local_interfaces > 0) {
 625         int i;
 626         for (i = 0; i < n_local_interfaces; i++) {
 627             SOCKADDR_IN *address =
 628                 (SOCKADDR_IN *)&local_interfaces[i].iiAddress;
 629             if (address->sin_addr.s_addr == addr.s_addr)
 630                 return 1;              /* this address is local */
 631         }
 632     }
 633     return 0;                  /* this address is not local */
 634 }
 635
 636 int sk_address_is_local(SockAddr addr)
 637 {
 638     SockAddrStep step;
 639     int family;
 640     START_STEP(addr, step);
 641     family = SOCKADDR_FAMILY(addr, step);
 642
 643 #ifndef NO_IPV6
 644     if (family == AF_INET6) {
 645         return IN6_IS_ADDR_LOOPBACK((const struct in6_addr *)step.ai->ai_addr);
 646     } else
 647 #endif
 648     if (family == AF_INET) {
 649 #ifndef NO_IPV6
 650         if (step.ai) {
 651             return ipv4_is_local_addr(((struct sockaddr_in *)step.ai->ai_addr)
 652                                       ->sin_addr);
 653         } else
 654 #endif
 655         {
 656             struct in_addr a;
 657             assert(addr->addresses && step.curraddr < addr->naddresses);
 658             a.s_addr = p_htonl(addr->addresses[step.curraddr]);
 659             return ipv4_is_local_addr(a);
 660         }
 661     } else {
 662         assert(family == AF_UNSPEC);
 663         return 0;                      /* we don't know; assume not */
 664     }
 665 }
 666
 667 int sk_addrtype(SockAddr addr)
 668 {
 669     SockAddrStep step;
 670     int family;
 671     START_STEP(addr, step);
 672     family = SOCKADDR_FAMILY(addr, step);
 673
 674     return (family == AF_INET ? ADDRTYPE_IPV4 :
 675 #ifndef NO_IPV6
 676             family == AF_INET6 ? ADDRTYPE_IPV6 :
 677 #endif
 678             ADDRTYPE_NAME);
 679 }
 680
 681 void sk_addrcopy(SockAddr addr, char *buf)
 682 {
 683     SockAddrStep step;
 684     int family;
 685     START_STEP(addr, step);
 686     family = SOCKADDR_FAMILY(addr, step);
 687
 688     assert(family != AF_UNSPEC);
 689 #ifndef NO_IPV6
 690     if (step.ai) {
 691         if (family == AF_INET)
 692             memcpy(buf, &((struct sockaddr_in *)step.ai->ai_addr)->sin_addr,
 693                    sizeof(struct in_addr));
 694         else if (family == AF_INET6)
 695             memcpy(buf, &((struct sockaddr_in6 *)step.ai->ai_addr)->sin6_addr,
 696                    sizeof(struct in6_addr));
 697         else
 698             assert(FALSE);
 699     } else
 700 #endif
 701     if (family == AF_INET) {
 702         struct in_addr a;
 703         assert(addr->addresses && step.curraddr < addr->naddresses);
 704         a.s_addr = p_htonl(addr->addresses[step.curraddr]);
 705         memcpy(buf, (char*) &a.s_addr, 4);
 706     }
 707 }
 708
 709 void sk_addr_free(SockAddr addr)
 710 {
 711     if (--addr->refcount > 0)
 712         return;
 713 #ifndef NO_IPV6
 714     if (addr->ais && p_freeaddrinfo)
 715         p_freeaddrinfo(addr->ais);
 716 #endif
 717     if (addr->addresses)
 718         sfree(addr->addresses);
 719     sfree(addr);
 720 }
 721
 722 SockAddr sk_addr_dup(SockAddr addr)
 723 {
 724     addr->refcount++;
 725     return addr;
 726 }
 727
 728 static Plug sk_tcp_plug(Socket sock, Plug p)
 729 {
 730     Actual_Socket s = (Actual_Socket) sock;
 731     Plug ret = s->plug;
 732     if (p)
 733         s->plug = p;
 734     return ret;
 735 }
 736
 737 static void sk_tcp_flush(Socket s)
 738 {
 739     /*
 740      * We send data to the socket as soon as we can anyway,
 741      * so we don't need to do anything here.  :-)
 742      */
 743 }
 744
 745 static void sk_tcp_close(Socket s);
 746 static int sk_tcp_write(Socket s, const char *data, int len);
 747 static int sk_tcp_write_oob(Socket s, const char *data, int len);
 748 static void sk_tcp_set_private_ptr(Socket s, void *ptr);
 749 static void *sk_tcp_get_private_ptr(Socket s);
 750 static void sk_tcp_set_frozen(Socket s, int is_frozen);
 751 static const char *sk_tcp_socket_error(Socket s);
 752
 753 extern char *do_select(SOCKET skt, int startup);
 754
 755 Socket sk_register(void *sock, Plug plug)
 756 {
 757     static const struct socket_function_table fn_table = {
 758         sk_tcp_plug,
 759         sk_tcp_close,
 760         sk_tcp_write,
 761         sk_tcp_write_oob,
 762         sk_tcp_flush,
 763         sk_tcp_set_private_ptr,
 764         sk_tcp_get_private_ptr,
 765         sk_tcp_set_frozen,
 766         sk_tcp_socket_error
 767     };
 768
 769     DWORD err;
 770     char *errstr;
 771     Actual_Socket ret;
 772
 773     /*
 774      * Create Socket structure.
 775      */
 776     ret = snew(struct Socket_tag);
 777     ret->fn = &fn_table;
 778     ret->error = NULL;
 779     ret->plug = plug;
 780     bufchain_init(&ret->output_data);
 781     ret->writable = 1;                 /* to start with */
 782     ret->sending_oob = 0;
 783     ret->frozen = 1;
 784     ret->frozen_readable = 0;
 785     ret->localhost_only = 0;           /* unused, but best init anyway */
 786     ret->pending_error = 0;
 787     ret->parent = ret->child = NULL;
 788     ret->addr = NULL;
 789
 790     ret->s = (SOCKET)sock;
 791
 792     if (ret->s == INVALID_SOCKET) {
 793         err = p_WSAGetLastError();
 794         ret->error = winsock_error_string(err);
 795         return (Socket) ret;
 796     }
 797
 798     ret->oobinline = 0;
 799
 800     /* Set up a select mechanism. This could be an AsyncSelect on a
 801      * window, or an EventSelect on an event object. */
 802     errstr = do_select(ret->s, 1);
 803     if (errstr) {
 804         ret->error = errstr;
 805         return (Socket) ret;
 806     }
 807
 808     add234(sktree, ret);
 809
 810     return (Socket) ret;
 811 }
 812
 813 static DWORD try_connect(Actual_Socket sock)
 814 {
 815     SOCKET s;
 816 #ifndef NO_IPV6
 817     SOCKADDR_IN6 a6;
 818 #endif
 819     SOCKADDR_IN a;
 820     DWORD err;
 821     char *errstr;
 822     short localport;
 823     int family;
 824
 825     if (sock->s != INVALID_SOCKET) {
 826         do_select(sock->s, 0);
 827         p_closesocket(sock->s);
 828     }
 829
 830     plug_log(sock->plug, 0, sock->addr, sock->port, NULL, 0);
 831
 832     /*
 833      * Open socket.
 834      */
 835     family = SOCKADDR_FAMILY(sock->addr, sock->step);
 836
 837     /*
 838      * Remove the socket from the tree before we overwrite its
 839      * internal socket id, because that forms part of the tree's
 840      * sorting criterion. We'll add it back before exiting this
 841      * function, whether we changed anything or not.
 842      */
 843     del234(sktree, sock);
 844
 845     s = p_socket(family, SOCK_STREAM, 0);
 846     sock->s = s;
 847
 848     if (s == INVALID_SOCKET) {
 849         err = p_WSAGetLastError();
 850         sock->error = winsock_error_string(err);
 851         goto ret;
 852     }
 853
 854     if (sock->oobinline) {
 855         BOOL b = TRUE;
 856         p_setsockopt(s, SOL_SOCKET, SO_OOBINLINE, (void *) &b, sizeof(b));
 857     }
 858
 859     if (sock->nodelay) {
 860         BOOL b = TRUE;
 861         p_setsockopt(s, IPPROTO_TCP, TCP_NODELAY, (void *) &b, sizeof(b));
 862     }
 863
 864     if (sock->keepalive) {
 865         BOOL b = TRUE;
 866         p_setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, (void *) &b, sizeof(b));
 867     }
 868
 869     /*
 870      * Bind to local address.
 871      */
 872     if (sock->privport)
 873         localport = 1023;              /* count from 1023 downwards */
 874     else
 875         localport = 0;                 /* just use port 0 (ie winsock picks) */
 876
 877     /* Loop round trying to bind */
 878     while (1) {
 879         int sockcode;
 880
 881 #ifndef NO_IPV6
 882         if (family == AF_INET6) {
 883             memset(&a6, 0, sizeof(a6));
 884             a6.sin6_family = AF_INET6;
 885           /*a6.sin6_addr = in6addr_any; */ /* == 0 done by memset() */
 886             a6.sin6_port = p_htons(localport);
 887         } else
 888 #endif
 889         {
 890             a.sin_family = AF_INET;
 891             a.sin_addr.s_addr = p_htonl(INADDR_ANY);
 892             a.sin_port = p_htons(localport);
 893         }
 894 #ifndef NO_IPV6
 895         sockcode = p_bind(s, (family == AF_INET6 ?
 896                               (struct sockaddr *) &a6 :
 897                               (struct sockaddr *) &a),
 898                           (family == AF_INET6 ? sizeof(a6) : sizeof(a)));
 899 #else
 900         sockcode = p_bind(s, (struct sockaddr *) &a, sizeof(a));
 901 #endif
 902         if (sockcode != SOCKET_ERROR) {
 903             err = 0;
 904             break;                     /* done */
 905         } else {
 906             err = p_WSAGetLastError();
 907             if (err != WSAEADDRINUSE)  /* failed, for a bad reason */
 908                 break;
 909         }
 910
 911         if (localport == 0)
 912             break;                     /* we're only looping once */
 913         localport--;
 914         if (localport == 0)
 915             break;                     /* we might have got to the end */
 916     }
 917
 918     if (err) {
 919         sock->error = winsock_error_string(err);
 920         goto ret;
 921     }
 922
 923     /*
 924      * Connect to remote address.
 925      */
 926 #ifndef NO_IPV6
 927     if (sock->step.ai) {
 928         if (family == AF_INET6) {
 929             a6.sin6_family = AF_INET6;
 930             a6.sin6_port = p_htons((short) sock->port);
 931             a6.sin6_addr =
 932                 ((struct sockaddr_in6 *) sock->step.ai->ai_addr)->sin6_addr;
 933             a6.sin6_flowinfo = ((struct sockaddr_in6 *) sock->step.ai->ai_addr)->sin6_flowinfo;
 934             a6.sin6_scope_id = ((struct sockaddr_in6 *) sock->step.ai->ai_addr)->sin6_scope_id;
 935         } else {
 936             a.sin_family = AF_INET;
 937             a.sin_addr =
 938                 ((struct sockaddr_in *) sock->step.ai->ai_addr)->sin_addr;
 939             a.sin_port = p_htons((short) sock->port);
 940         }
 941     } else
 942 #endif
 943     {
 944         assert(sock->addr->addresses && sock->step.curraddr < sock->addr->naddresses);
 945         a.sin_family = AF_INET;
 946         a.sin_addr.s_addr = p_htonl(sock->addr->addresses[sock->step.curraddr]);
 947         a.sin_port = p_htons((short) sock->port);
 948     }
 949
 950     /* Set up a select mechanism. This could be an AsyncSelect on a
 951      * window, or an EventSelect on an event object. */
 952     errstr = do_select(s, 1);
 953     if (errstr) {
 954         sock->error = errstr;
 955         err = 1;
 956         goto ret;
 957     }
 958
 959     if ((
 960 #ifndef NO_IPV6
 961             p_connect(s,
 962                       ((family == AF_INET6) ? (struct sockaddr *) &a6 :
 963                        (struct sockaddr *) &a),
 964                       (family == AF_INET6) ? sizeof(a6) : sizeof(a))
 965 #else
 966             p_connect(s, (struct sockaddr *) &a, sizeof(a))
 967 #endif
 968         ) == SOCKET_ERROR) {
 969         err = p_WSAGetLastError();
 970         /*
 971          * We expect a potential EWOULDBLOCK here, because the
 972          * chances are the front end has done a select for
 973          * FD_CONNECT, so that connect() will complete
 974          * asynchronously.
 975          */
 976         if ( err != WSAEWOULDBLOCK ) {
 977             sock->error = winsock_error_string(err);
 978             goto ret;
 979         }
 980     } else {
 981         /*
 982          * If we _don't_ get EWOULDBLOCK, the connect has completed
 983          * and we should set the socket as writable.
 984          */
 985         sock->writable = 1;
 986     }
 987
 988     err = 0;
 989
 990     ret:
 991
 992     /*
 993      * No matter what happened, put the socket back in the tree.
 994      */
 995     add234(sktree, sock);
 996
 997     if (err)
 998         plug_log(sock->plug, 1, sock->addr, sock->port, sock->error, err);
 999     return err;
1000 }
1001
1002 Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
1003               int nodelay, int keepalive, Plug plug)
1004 {
1005     static const struct socket_function_table fn_table = {
1006         sk_tcp_plug,
1007         sk_tcp_close,
1008         sk_tcp_write,
1009         sk_tcp_write_oob,
1010         sk_tcp_flush,
1011         sk_tcp_set_private_ptr,
1012         sk_tcp_get_private_ptr,
1013         sk_tcp_set_frozen,
1014         sk_tcp_socket_error
1015     };
1016
1017     Actual_Socket ret;
1018     DWORD err;
1019
1020     /*
1021      * Create Socket structure.
1022      */
1023     ret = snew(struct Socket_tag);
1024     ret->fn = &fn_table;
1025     ret->error = NULL;
1026     ret->plug = plug;
1027     bufchain_init(&ret->output_data);
1028     ret->connected = 0;                /* to start with */
1029     ret->writable = 0;                 /* to start with */
1030     ret->sending_oob = 0;
1031     ret->frozen = 0;
1032     ret->frozen_readable = 0;
1033     ret->localhost_only = 0;           /* unused, but best init anyway */
1034     ret->pending_error = 0;
1035     ret->parent = ret->child = NULL;
1036     ret->oobinline = oobinline;
1037     ret->nodelay = nodelay;
1038     ret->keepalive = keepalive;
1039     ret->privport = privport;
1040     ret->port = port;
1041     ret->addr = addr;
1042     START_STEP(ret->addr, ret->step);
1043     ret->s = INVALID_SOCKET;
1044
1045     err = 0;
1046     do {
1047         err = try_connect(ret);
1048     } while (err && sk_nextaddr(ret->addr, &ret->step));
1049
1050     return (Socket) ret;
1051 }
1052
1053 Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only,
1054                       int orig_address_family)
1055 {
1056     static const struct socket_function_table fn_table = {
1057         sk_tcp_plug,
1058         sk_tcp_close,
1059         sk_tcp_write,
1060         sk_tcp_write_oob,
1061         sk_tcp_flush,
1062         sk_tcp_set_private_ptr,
1063         sk_tcp_get_private_ptr,
1064         sk_tcp_set_frozen,
1065         sk_tcp_socket_error
1066     };
1067
1068     SOCKET s;
1069 #ifndef NO_IPV6
1070     SOCKADDR_IN6 a6;
1071 #endif
1072     SOCKADDR_IN a;
1073
1074     DWORD err;
1075     char *errstr;
1076     Actual_Socket ret;
1077     int retcode;
1078     int on = 1;
1079
1080     int address_family;
1081
1082     /*
1083      * Create Socket structure.
1084      */
1085     ret = snew(struct Socket_tag);
1086     ret->fn = &fn_table;
1087     ret->error = NULL;
1088     ret->plug = plug;
1089     bufchain_init(&ret->output_data);
1090     ret->writable = 0;                 /* to start with */
1091     ret->sending_oob = 0;
1092     ret->frozen = 0;
1093     ret->frozen_readable = 0;
1094     ret->localhost_only = local_host_only;
1095     ret->pending_error = 0;
1096     ret->parent = ret->child = NULL;
1097     ret->addr = NULL;
1098
1099     /*
1100      * Translate address_family from platform-independent constants
1101      * into local reality.
1102      */
1103     address_family = (orig_address_family == ADDRTYPE_IPV4 ? AF_INET :
1104 #ifndef NO_IPV6
1105                       orig_address_family == ADDRTYPE_IPV6 ? AF_INET6 :
1106 #endif
1107                       AF_UNSPEC);
1108
1109     /*
1110      * Our default, if passed the `don't care' value
1111      * ADDRTYPE_UNSPEC, is to listen on IPv4. If IPv6 is supported,
1112      * we will also set up a second socket listening on IPv6, but
1113      * the v4 one is primary since that ought to work even on
1114      * non-v6-supporting systems.
1115      */
1116     if (address_family == AF_UNSPEC) address_family = AF_INET;
1117
1118     /*
1119      * Open socket.
1120      */
1121     s = p_socket(address_family, SOCK_STREAM, 0);
1122     ret->s = s;
1123
1124     if (s == INVALID_SOCKET) {
1125         err = p_WSAGetLastError();
1126         ret->error = winsock_error_string(err);
1127         return (Socket) ret;
1128     }
1129
1130     ret->oobinline = 0;
1131
1132     p_setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char *)&on, sizeof(on));
1133
1134 #ifndef NO_IPV6
1135         if (address_family == AF_INET6) {
1136             memset(&a6, 0, sizeof(a6));
1137             a6.sin6_family = AF_INET6;
1138             /* FIXME: srcaddr is ignored for IPv6, because I (SGT) don't
1139              * know how to do it. :-)
1140              * (jeroen:) saddr is specified as an address.. eg 2001:db8::1
1141              * Thus we need either a parser that understands [2001:db8::1]:80
1142              * style addresses and/or enhance this to understand hostnames too. */
1143             if (local_host_only)
1144                 a6.sin6_addr = in6addr_loopback;
1145             else
1146                 a6.sin6_addr = in6addr_any;
1147             a6.sin6_port = p_htons(port);
1148         } else
1149 #endif
1150         {
1151             int got_addr = 0;
1152             a.sin_family = AF_INET;
1153
1154             /*
1155              * Bind to source address. First try an explicitly
1156              * specified one...
1157              */
1158             if (srcaddr) {
1159                 a.sin_addr.s_addr = p_inet_addr(srcaddr);
1160                 if (a.sin_addr.s_addr != INADDR_NONE) {
1161                     /* Override localhost_only with specified listen addr. */
1162                     ret->localhost_only = ipv4_is_loopback(a.sin_addr);
1163                     got_addr = 1;
1164                 }
1165             }
1166
1167             /*
1168              * ... and failing that, go with one of the standard ones.
1169              */
1170             if (!got_addr) {
1171                 if (local_host_only)
1172                     a.sin_addr.s_addr = p_htonl(INADDR_LOOPBACK);
1173                 else
1174                     a.sin_addr.s_addr = p_htonl(INADDR_ANY);
1175             }
1176
1177             a.sin_port = p_htons((short)port);
1178         }
1179 #ifndef NO_IPV6
1180         retcode = p_bind(s, (address_family == AF_INET6 ?
1181                            (struct sockaddr *) &a6 :
1182                            (struct sockaddr *) &a),
1183                        (address_family ==
1184                         AF_INET6 ? sizeof(a6) : sizeof(a)));
1185 #else
1186         retcode = p_bind(s, (struct sockaddr *) &a, sizeof(a));
1187 #endif
1188         if (retcode != SOCKET_ERROR) {
1189             err = 0;
1190         } else {
1191             err = p_WSAGetLastError();
1192         }
1193
1194     if (err) {
1195         p_closesocket(s);
1196         ret->error = winsock_error_string(err);
1197         return (Socket) ret;
1198     }
1199
1200
1201     if (p_listen(s, SOMAXCONN) == SOCKET_ERROR) {
1202         p_closesocket(s);
1203         ret->error = winsock_error_string(err);
1204         return (Socket) ret;
1205     }
1206
1207     /* Set up a select mechanism. This could be an AsyncSelect on a
1208      * window, or an EventSelect on an event object. */
1209     errstr = do_select(s, 1);
1210     if (errstr) {
1211         p_closesocket(s);
1212         ret->error = errstr;
1213         return (Socket) ret;
1214     }
1215
1216     add234(sktree, ret);
1217
1218 #ifndef NO_IPV6
1219     /*
1220      * If we were given ADDRTYPE_UNSPEC, we must also create an
1221      * IPv6 listening socket and link it to this one.
1222      */
1223     if (address_family == AF_INET && orig_address_family == ADDRTYPE_UNSPEC) {
1224         Actual_Socket other;
1225
1226         other = (Actual_Socket) sk_newlistener(srcaddr, port, plug,
1227                                                local_host_only, ADDRTYPE_IPV6);
1228
1229         if (other) {
1230             if (!other->error) {
1231                 other->parent = ret;
1232                 ret->child = other;
1233             } else {
1234                 sfree(other);
1235             }
1236         }
1237     }
1238 #endif
1239
1240     return (Socket) ret;
1241 }
1242
1243 static void sk_tcp_close(Socket sock)
1244 {
1245     extern char *do_select(SOCKET skt, int startup);
1246     Actual_Socket s = (Actual_Socket) sock;
1247
1248     if (s->child)
1249         sk_tcp_close((Socket)s->child);
1250
1251     del234(sktree, s);
1252     do_select(s->s, 0);
1253     p_closesocket(s->s);
1254     if (s->addr)
1255         sk_addr_free(s->addr);
1256     sfree(s);
1257 }
1258
1259 /*
1260  * The function which tries to send on a socket once it's deemed
1261  * writable.
1262  */
1263 void try_send(Actual_Socket s)
1264 {
1265     while (s->sending_oob || bufchain_size(&s->output_data) > 0) {
1266         int nsent;
1267         DWORD err;
1268         void *data;
1269         int len, urgentflag;
1270
1271         if (s->sending_oob) {
1272             urgentflag = MSG_OOB;
1273             len = s->sending_oob;
1274             data = &s->oobdata;
1275         } else {
1276             urgentflag = 0;
1277             bufchain_prefix(&s->output_data, &data, &len);
1278         }
1279         nsent = p_send(s->s, data, len, urgentflag);
1280         noise_ultralight(nsent);
1281         if (nsent <= 0) {
1282             err = (nsent < 0 ? p_WSAGetLastError() : 0);
1283             if ((err < WSABASEERR && nsent < 0) || err == WSAEWOULDBLOCK) {
1284                 /*
1285                  * Perfectly normal: we've sent all we can for the moment.
1286                  *
1287                  * (Some WinSock send() implementations can return
1288                  * <0 but leave no sensible error indication -
1289                  * WSAGetLastError() is called but returns zero or
1290                  * a small number - so we check that case and treat
1291                  * it just like WSAEWOULDBLOCK.)
1292                  */
1293                 s->writable = FALSE;
1294                 return;
1295             } else if (nsent == 0 ||
1296                        err == WSAECONNABORTED || err == WSAECONNRESET) {
1297                 /*
1298                  * If send() returns CONNABORTED or CONNRESET, we
1299                  * unfortunately can't just call plug_closing(),
1300                  * because it's quite likely that we're currently
1301                  * _in_ a call from the code we'd be calling back
1302                  * to, so we'd have to make half the SSH code
1303                  * reentrant. Instead we flag a pending error on
1304                  * the socket, to be dealt with (by calling
1305                  * plug_closing()) at some suitable future moment.
1306                  */
1307                 s->pending_error = err;
1308                 return;
1309             } else {
1310                 /* We're inside the Windows frontend here, so we know
1311                  * that the frontend handle is unnecessary. */
1312                 logevent(NULL, winsock_error_string(err));
1313                 fatalbox("%s", winsock_error_string(err));
1314             }
1315         } else {
1316             if (s->sending_oob) {
1317                 if (nsent < len) {
1318                     memmove(s->oobdata, s->oobdata+nsent, len-nsent);
1319                     s->sending_oob = len - nsent;
1320                 } else {
1321                     s->sending_oob = 0;
1322                 }
1323             } else {
1324                 bufchain_consume(&s->output_data, nsent);
1325             }
1326         }
1327     }
1328 }
1329
1330 static int sk_tcp_write(Socket sock, const char *buf, int len)
1331 {
1332     Actual_Socket s = (Actual_Socket) sock;
1333
1334     /*
1335      * Add the data to the buffer list on the socket.
1336      */
1337     bufchain_add(&s->output_data, buf, len);
1338
1339     /*
1340      * Now try sending from the start of the buffer list.
1341      */
1342     if (s->writable)
1343         try_send(s);
1344
1345     return bufchain_size(&s->output_data);
1346 }
1347
1348 static int sk_tcp_write_oob(Socket sock, const char *buf, int len)
1349 {
1350     Actual_Socket s = (Actual_Socket) sock;
1351
1352     /*
1353      * Replace the buffer list on the socket with the data.
1354      */
1355     bufchain_clear(&s->output_data);
1356     assert(len <= sizeof(s->oobdata));
1357     memcpy(s->oobdata, buf, len);
1358     s->sending_oob = len;
1359
1360     /*
1361      * Now try sending from the start of the buffer list.
1362      */
1363     if (s->writable)
1364         try_send(s);
1365
1366     return s->sending_oob;
1367 }
1368
1369 int select_result(WPARAM wParam, LPARAM lParam)
1370 {
1371     int ret, open;
1372     DWORD err;
1373     char buf[20480];                   /* nice big buffer for plenty of speed */
1374     Actual_Socket s;
1375     u_long atmark;
1376
1377     /* wParam is the socket itself */
1378
1379     if (wParam == 0)
1380         return 1;                      /* boggle */
1381
1382     s = find234(sktree, (void *) wParam, cmpforsearch);
1383     if (!s)
1384         return 1;                      /* boggle */
1385
1386     if ((err = WSAGETSELECTERROR(lParam)) != 0) {
1387         /*
1388          * An error has occurred on this socket. Pass it to the
1389          * plug.
1390          */
1391         if (s->addr) {
1392             plug_log(s->plug, 1, s->addr, s->port,
1393                      winsock_error_string(err), err);
1394             while (s->addr && sk_nextaddr(s->addr, &s->step)) {
1395                 err = try_connect(s);
1396             }
1397         }
1398         if (err != 0)
1399             return plug_closing(s->plug, winsock_error_string(err), err, 0);
1400         else
1401             return 1;
1402     }
1403
1404     noise_ultralight(lParam);
1405
1406     switch (WSAGETSELECTEVENT(lParam)) {
1407       case FD_CONNECT:
1408         s->connected = s->writable = 1;
1409         /*
1410          * Once a socket is connected, we can stop falling
1411          * back through the candidate addresses to connect
1412          * to.
1413          */
1414         if (s->addr) {
1415             sk_addr_free(s->addr);
1416             s->addr = NULL;
1417         }
1418         break;
1419       case FD_READ:
1420         /* In the case the socket is still frozen, we don't even bother */
1421         if (s->frozen) {
1422             s->frozen_readable = 1;
1423             break;
1424         }
1425
1426         /*
1427          * We have received data on the socket. For an oobinline
1428          * socket, this might be data _before_ an urgent pointer,
1429          * in which case we send it to the back end with type==1
1430          * (data prior to urgent).
1431          */
1432         if (s->oobinline) {
1433             atmark = 1;
1434             p_ioctlsocket(s->s, SIOCATMARK, &atmark);
1435             /*
1436              * Avoid checking the return value from ioctlsocket(),
1437              * on the grounds that some WinSock wrappers don't
1438              * support it. If it does nothing, we get atmark==1,
1439              * which is equivalent to `no OOB pending', so the
1440              * effect will be to non-OOB-ify any OOB data.
1441              */
1442         } else
1443             atmark = 1;
1444
1445         ret = p_recv(s->s, buf, sizeof(buf), 0);
1446         noise_ultralight(ret);
1447         if (ret < 0) {
1448             err = p_WSAGetLastError();
1449             if (err == WSAEWOULDBLOCK) {
1450                 break;
1451             }
1452         }
1453         if (ret < 0) {
1454             return plug_closing(s->plug, winsock_error_string(err), err,
1455                                 0);
1456         } else if (0 == ret) {
1457             return plug_closing(s->plug, NULL, 0, 0);
1458         } else {
1459             return plug_receive(s->plug, atmark ? 0 : 1, buf, ret);
1460         }
1461         break;
1462       case FD_OOB:
1463         /*
1464          * This will only happen on a non-oobinline socket. It
1465          * indicates that we can immediately perform an OOB read
1466          * and get back OOB data, which we will send to the back
1467          * end with type==2 (urgent data).
1468          */
1469         ret = p_recv(s->s, buf, sizeof(buf), MSG_OOB);
1470         noise_ultralight(ret);
1471         if (ret <= 0) {
1472             char *str = (ret == 0 ? "Internal networking trouble" :
1473                          winsock_error_string(p_WSAGetLastError()));
1474             /* We're inside the Windows frontend here, so we know
1475              * that the frontend handle is unnecessary. */
1476             logevent(NULL, str);
1477             fatalbox("%s", str);
1478         } else {
1479             return plug_receive(s->plug, 2, buf, ret);
1480         }
1481         break;
1482       case FD_WRITE:
1483         {
1484             int bufsize_before, bufsize_after;
1485             s->writable = 1;
1486             bufsize_before = s->sending_oob + bufchain_size(&s->output_data);
1487             try_send(s);
1488             bufsize_after = s->sending_oob + bufchain_size(&s->output_data);
1489             if (bufsize_after < bufsize_before)
1490                 plug_sent(s->plug, bufsize_after);
1491         }
1492         break;
1493       case FD_CLOSE:
1494         /* Signal a close on the socket. First read any outstanding data. */
1495         open = 1;
1496         do {
1497             ret = p_recv(s->s, buf, sizeof(buf), 0);
1498             if (ret < 0) {
1499                 err = p_WSAGetLastError();
1500                 if (err == WSAEWOULDBLOCK)
1501                     break;
1502                 return plug_closing(s->plug, winsock_error_string(err),
1503                                     err, 0);
1504             } else {
1505                 if (ret)
1506                     open &= plug_receive(s->plug, 0, buf, ret);
1507                 else
1508                     open &= plug_closing(s->plug, NULL, 0, 0);
1509             }
1510         } while (ret > 0);
1511         return open;
1512        case FD_ACCEPT:
1513         {
1514 #ifdef NO_IPV6
1515             struct sockaddr_in isa;
1516 #else
1517             struct sockaddr_storage isa;
1518 #endif
1519             int addrlen = sizeof(isa);
1520             SOCKET t;  /* socket of connection */
1521
1522             memset(&isa, 0, sizeof(isa));
1523             err = 0;
1524             t = p_accept(s->s,(struct sockaddr *)&isa,&addrlen);
1525             if (t == INVALID_SOCKET)
1526             {
1527                 err = p_WSAGetLastError();
1528                 if (err == WSATRY_AGAIN)
1529                     break;
1530             }
1531 #ifndef NO_IPV6
1532             if (isa.ss_family == AF_INET &&
1533                 s->localhost_only &&
1534                 !ipv4_is_local_addr(((struct sockaddr_in *)&isa)->sin_addr))
1535 #else
1536             if (s->localhost_only && !ipv4_is_local_addr(isa.sin_addr))
1537 #endif
1538             {
1539                 p_closesocket(t);      /* dodgy WinSock let nonlocal through */
1540             } else if (plug_accepting(s->plug, (void*)t)) {
1541                 p_closesocket(t);      /* denied or error */
1542             }
1543         }
1544     }
1545
1546     return 1;
1547 }
1548
1549 /*
1550  * Deal with socket errors detected in try_send().
1551  */
1552 void net_pending_errors(void)
1553 {
1554     int i;
1555     Actual_Socket s;
1556
1557     /*
1558      * This might be a fiddly business, because it's just possible
1559      * that handling a pending error on one socket might cause
1560      * others to be closed. (I can't think of any reason this might
1561      * happen in current SSH implementation, but to maintain
1562      * generality of this network layer I'll assume the worst.)
1563      *
1564      * So what we'll do is search the socket list for _one_ socket
1565      * with a pending error, and then handle it, and then search
1566      * the list again _from the beginning_. Repeat until we make a
1567      * pass with no socket errors present. That way we are
1568      * protected against the socket list changing under our feet.
1569      */
1570
1571     do {
1572         for (i = 0; (s = index234(sktree, i)) != NULL; i++) {
1573             if (s->pending_error) {
1574                 /*
1575                  * An error has occurred on this socket. Pass it to the
1576                  * plug.
1577                  */
1578                 plug_closing(s->plug,
1579                              winsock_error_string(s->pending_error),
1580                              s->pending_error, 0);
1581                 break;
1582             }
1583         }
1584     } while (s);
1585 }
1586
1587 /*
1588  * Each socket abstraction contains a `void *' private field in
1589  * which the client can keep state.
1590  */
1591 static void sk_tcp_set_private_ptr(Socket sock, void *ptr)
1592 {
1593     Actual_Socket s = (Actual_Socket) sock;
1594     s->private_ptr = ptr;
1595 }
1596
1597 static void *sk_tcp_get_private_ptr(Socket sock)
1598 {
1599     Actual_Socket s = (Actual_Socket) sock;
1600     return s->private_ptr;
1601 }
1602
1603 /*
1604  * Special error values are returned from sk_namelookup and sk_new
1605  * if there's a problem. These functions extract an error message,
1606  * or return NULL if there's no problem.
1607  */
1608 const char *sk_addr_error(SockAddr addr)
1609 {
1610     return addr->error;
1611 }
1612 static const char *sk_tcp_socket_error(Socket sock)
1613 {
1614     Actual_Socket s = (Actual_Socket) sock;
1615     return s->error;
1616 }
1617
1618 static void sk_tcp_set_frozen(Socket sock, int is_frozen)
1619 {
1620     Actual_Socket s = (Actual_Socket) sock;
1621     if (s->frozen == is_frozen)
1622         return;
1623     s->frozen = is_frozen;
1624     if (!is_frozen) {
1625         do_select(s->s, 1);
1626         if (s->frozen_readable) {
1627             char c;
1628             p_recv(s->s, &c, 1, MSG_PEEK);
1629         }
1630     }
1631     s->frozen_readable = 0;
1632 }
1633
1634 void socket_reselect_all(void)
1635 {
1636     Actual_Socket s;
1637     int i;
1638
1639     for (i = 0; (s = index234(sktree, i)) != NULL; i++) {
1640         if (!s->frozen)
1641             do_select(s->s, 1);
1642     }
1643 }
1644
1645 /*
1646  * For Plink: enumerate all sockets currently active.
1647  */
1648 SOCKET first_socket(int *state)
1649 {
1650     Actual_Socket s;
1651     *state = 0;
1652     s = index234(sktree, (*state)++);
1653     return s ? s->s : INVALID_SOCKET;
1654 }
1655
1656 SOCKET next_socket(int *state)
1657 {
1658     Actual_Socket s = index234(sktree, (*state)++);
1659     return s ? s->s : INVALID_SOCKET;
1660 }
1661
1662 extern int socket_writable(SOCKET skt)
1663 {
1664     Actual_Socket s = find234(sktree, (void *)skt, cmpforsearch);
1665
1666     if (s)
1667         return bufchain_size(&s->output_data) > 0;
1668     else
1669         return 0;
1670 }
1671
1672 int net_service_lookup(char *service)
1673 {
1674     struct servent *se;
1675     se = p_getservbyname(service, NULL);
1676     if (se != NULL)
1677         return p_ntohs(se->s_port);
1678     else
1679         return 0;
1680 }
1681
1682 char *get_hostname(void)
1683 {
1684     int len = 128;
1685     char *hostname = NULL;
1686     do {
1687         len *= 2;
1688         hostname = sresize(hostname, len, char);
1689         if (p_gethostname(hostname, len) < 0) {
1690             sfree(hostname);
1691             hostname = NULL;
1692             break;
1693         }
1694     } while (strlen(hostname) >= (size_t)(len-1));
1695     return hostname;
1696 }
1697
1698 SockAddr platform_get_x11_unix_address(const char *display, int displaynum,
1699                                        char **canonicalname)
1700 {
1701     SockAddr ret = snew(struct SockAddr_tag);
1702     memset(ret, 0, sizeof(struct SockAddr_tag));
1703     ret->error = "unix sockets not supported on this platform";
1704     ret->refcount = 1;
1705     return ret;
1706 }