[u/mdw/putty] / winnet.c

/*
 * Windows networking abstraction.
 *
 * Due to this clean abstraction it was possible
 * to easily implement IPv6 support :)
 *
 * IPv6 patch 1 (27 October 2000) Jeroen Massar <jeroen@unfix.org>
 *  - Preliminary hacked IPv6 support.
 *    - Connecting to IPv6 address (eg fec0:4242:4242:100:2d0:b7ff:fe8f:5d42) works.
 *    - Connecting to IPv6 hostname (eg heaven.ipv6.unfix.org) works.
 *  - Compiles as either IPv4 or IPv6.
 *
 * IPv6 patch 2 (29 October 2000) Jeroen Massar <jeroen@unfix.org>
 *  - When compiled as IPv6 it also allows connecting to IPv4 hosts.
 *  - Added some more documentation.
 *
 * IPv6 patch 3 (18 November 2000) Jeroen Massar <jeroen@unfix.org>
 *  - It now supports dynamically loading the IPv6 resolver dll's.
 *    This way we should be able to distribute one (1) binary
 *    which supports both IPv4 and IPv6.
 *  - getaddrinfo() and getnameinfo() are loaded dynamicaly if possible.
 *  - in6addr_any is defined in this file so we don't need to link to wship6.lib
 *  - The patch is now more unified so that we can still
 *    remove all IPv6 support by undef'ing IPV6.
 *    But where it fallsback to IPv4 it uses the IPv4 code which is already in place...
 *  - Canonical name resolving works.
 *
 * IPv6 patch 4 (07 January 2001) Jeroen Massar <jeroen@unfix.org>
 *  - patch against CVS of today, will be submitted to the bugs list
 *    as a 'cvs diff -u' on Simon's request...
 *
 */

/*
 * Define IPV6 to have IPv6 on-the-fly-loading support.
 * This means that one doesn't have to have an IPv6 stack to use it.
 * But if an IPv6 stack is found it is used with a fallback to IPv4.
 */
/* #define IPV6 1 */

#ifdef IPV6
#include <winsock2.h>
#include <ws2tcpip.h>
#include <tpipv6.h>
#else
#include <winsock.h>
#endif
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>

#include "putty.h"
#include "network.h"
#include "tree234.h"

#define BUFFER_GRANULE 512

struct Socket_tag {
    char *error;
    SOCKET s;
    sk_receiver_t receiver;
    void *private_ptr;
    struct buffer *head, *tail;
    int writable;
    int sending_oob;
    int oobinline;
};

struct SockAddr_tag {
    char *error;
    /* address family this belongs to, AF_INET for IPv4, AF_INET6 for IPv6. */
    int family;			     
    unsigned long address;	       /* Address IPv4 style. */
#ifdef IPV6
    struct addrinfo *ai;	       /* Address IPv6 style. */
#endif
    /*
     * We need to have this lengthy enough to hold *any* hostname
     * (including IPv6 reverse...)
     */
    char realhost[8192];
};

struct buffer {
    struct buffer *next;
    int buflen, bufpos;
    char buf[BUFFER_GRANULE];
};

static tree234 *sktree;

static int cmpfortree(void *av, void *bv) {
    Socket a = (Socket)av, b = (Socket)bv;
    unsigned long as = (unsigned long)a->s, bs = (unsigned long)b->s;
    if (as < bs) return -1;
    if (as > bs) return +1;
    return 0;
}

static int cmpforsearch(void *av, void *bv) {
    Socket b = (Socket)bv;
    unsigned long as = (unsigned long)av, bs = (unsigned long)b->s;
    if (as < bs) return -1;
    if (as > bs) return +1;
    return 0;
}

void sk_init(void) {
    sktree = newtree234(cmpfortree);
}

char *winsock_error_string(int error) {
    switch (error) {
      case WSAEACCES: return "Network error: Permission denied";
      case WSAEADDRINUSE: return "Network error: Address already in use";
      case WSAEADDRNOTAVAIL: return "Network error: Cannot assign requested address";
      case WSAEAFNOSUPPORT: return "Network error: Address family not supported by protocol family";
      case WSAEALREADY: return "Network error: Operation already in progress";
      case WSAECONNABORTED: return "Network error: Software caused connection abort";
      case WSAECONNREFUSED: return "Network error: Connection refused";
      case WSAECONNRESET: return "Network error: Connection reset by peer";
      case WSAEDESTADDRREQ: return "Network error: Destination address required";
      case WSAEFAULT: return "Network error: Bad address";
      case WSAEHOSTDOWN: return "Network error: Host is down";
      case WSAEHOSTUNREACH: return "Network error: No route to host";
      case WSAEINPROGRESS: return "Network error: Operation now in progress";
      case WSAEINTR: return "Network error: Interrupted function call";
      case WSAEINVAL: return "Network error: Invalid argument";
      case WSAEISCONN: return "Network error: Socket is already connected";
      case WSAEMFILE: return "Network error: Too many open files";
      case WSAEMSGSIZE: return "Network error: Message too long";
      case WSAENETDOWN: return "Network error: Network is down";
      case WSAENETRESET: return "Network error: Network dropped connection on reset";
      case WSAENETUNREACH: return "Network error: Network is unreachable";
      case WSAENOBUFS: return "Network error: No buffer space available";
      case WSAENOPROTOOPT: return "Network error: Bad protocol option";
      case WSAENOTCONN: return "Network error: Socket is not connected";
      case WSAENOTSOCK: return "Network error: Socket operation on non-socket";
      case WSAEOPNOTSUPP: return "Network error: Operation not supported";
      case WSAEPFNOSUPPORT: return "Network error: Protocol family not supported";
      case WSAEPROCLIM: return "Network error: Too many processes";
      case WSAEPROTONOSUPPORT: return "Network error: Protocol not supported";
      case WSAEPROTOTYPE: return "Network error: Protocol wrong type for socket";
      case WSAESHUTDOWN: return "Network error: Cannot send after socket shutdown";
      case WSAESOCKTNOSUPPORT: return "Network error: Socket type not supported";
      case WSAETIMEDOUT: return "Network error: Connection timed out";
      case WSAEWOULDBLOCK: return "Network error: Resource temporarily unavailable";
      case WSAEDISCON: return "Network error: Graceful shutdown in progress";
      default: return "Unknown network error";
    }
}

SockAddr sk_namelookup(char *host, char **canonicalname)
{
    SockAddr ret = smalloc(sizeof(struct SockAddr_tag));
    unsigned long a;
    struct hostent *h = NULL;

    /* Clear the structure and default to IPv4. */
    memset(ret, 0, sizeof(struct SockAddr_tag));
    ret->family = 0;		       /* We set this one when we have resolved the host. */
    *canonicalname = ret->realhost;    /* This makes sure we always have a hostname to return. */

    if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE)
    {
#ifdef IPV6

	/* Try to get the getaddrinfo() function from wship6.dll */
	/* This way one doesn't need to have IPv6 dll's to use PuTTY and
	 * it will fallback to IPv4. */
	typedef int (CALLBACK* FGETADDRINFO)(const char *nodename,
					     const char *servname,
					     const struct addrinfo *hints,
					     struct addrinfo **res);
	FGETADDRINFO fGetAddrInfo = NULL;

	HINSTANCE dllWSHIP6 = LoadLibrary("wship6.dll");
	if (dllWSHIP6)
	    fGetAddrInfo = (FGETADDRINFO)GetProcAddress(dllWSHIP6,
							"getaddrinfo");

	/*
	 * Use fGetAddrInfo when it's available (which usually also
	 * means IPv6 is installed...)
	 */
	if (fGetAddrInfo)
	{
	    /*debug(("Resolving \"%s\" with getaddrinfo()  (IPv4+IPv6 capable)...\n", host)); */
	    if (fGetAddrInfo(host, NULL, NULL, &ret->ai) == 0)
		ret->family = ret->ai->ai_family;
	}
	else
#endif
	    /*
	     * Otherwise use the IPv4-only gethostbyname...
	     * (NOTE: we don't use gethostbyname as a
	     * fallback!)
	     */
	    if (ret->family == 0)
	{
	    /*debug(("Resolving \"%s\" with gethostbyname() (IPv4 only)...\n", host)); */
	    if (h = gethostbyname(host)) ret->family = AF_INET;
	}
	/*debug(("Done resolving...(family is %d) AF_INET = %d, AF_INET6 = %d\n", ret->family, AF_INET, AF_INET6)); */

	if (ret->family == 0)
	{
	    DWORD err = WSAGetLastError();
	    ret->error = (err == WSAENETDOWN ? "Network is down" :
			  err == WSAHOST_NOT_FOUND ? "Host does not exist" :
			  err == WSATRY_AGAIN ? "Host not found" :
#ifdef IPV6
			  fGetAddrInfo ? "getaddrinfo: unknown error" :
#endif
			  "gethostbyname: unknown error");
#ifdef DEBUG
	    {
		LPVOID lpMsgBuf;
		FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS, NULL, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPTSTR)&lpMsgBuf,	0,	NULL);
		/*debug(("Error %ld: %s (h=%lx)\n", err, lpMsgBuf, h));*/
		/* Free the buffer. */
		LocalFree(lpMsgBuf);
	    }
#endif
	}
	else
	{
	    ret->error = NULL;

#ifdef IPV6
	    /* If we got an address info use that... */
	    if (ret->ai)
	    {
		typedef int (CALLBACK* FGETNAMEINFO)
		    (const struct sockaddr FAR *sa, socklen_t salen,
		     char FAR * host, size_t hostlen, char FAR * serv,
		     size_t servlen, int flags);
		FGETNAMEINFO fGetNameInfo = NULL;

		/* Are we in IPv4 fallback mode? */
		/* We put the IPv4 address into the a variable so we can further-on use the IPv4 code... */
		if (ret->family == AF_INET)
		    memcpy(&a, (char *)&((SOCKADDR_IN *)ret->ai->ai_addr)->sin_addr, sizeof(a));

		/* Now let's find that canonicalname... */
		if ((dllWSHIP6) && (fGetNameInfo = (FGETNAMEINFO)GetProcAddress(dllWSHIP6, "getnameinfo")))
		{
		    if (fGetNameInfo((struct sockaddr *)ret->ai->ai_addr,
				     ret->family == AF_INET ?
				     sizeof(SOCKADDR_IN) :
				     sizeof(SOCKADDR_IN6), ret->realhost,
				     sizeof(ret->realhost), NULL,
				     0, 0) != 0)
		    {
			strncpy(ret->realhost, host,
				sizeof(ret->realhost));
		    }
		}
	    }
	    /* We used the IPv4-only gethostbyname()... */
	    else
	    {
#endif
		memcpy(&a, h->h_addr, sizeof(a));
		/* This way we are always sure the h->h_name is valid :) */
		strncpy(ret->realhost, h->h_name, sizeof(ret->realhost));
#ifdef IPV6
	    }
#endif
	}
#ifdef IPV6
	FreeLibrary(dllWSHIP6);
#endif
    }
    else
    {
        /*
         * Hack inserted to deal with problems with numeric IPs.
         * FIXME: how will this work in IPv6?
         */
        ret->family = AF_INET;
	*canonicalname = host;
    }
    ret->address = ntohl(a);
    return ret;
}

void sk_addr_free(SockAddr addr) {
    sfree(addr);
}

Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
              sk_receiver_t receiver) {
    SOCKET s;
#ifdef IPV6
    SOCKADDR_IN6 a6;
#endif
    SOCKADDR_IN a;
    DWORD err;
    char *errstr;
    Socket ret;
    extern char *do_select(SOCKET skt, int startup);
    short localport;

    /*
     * Create Socket structure.
     */
    ret = smalloc(sizeof(struct Socket_tag));
    ret->error = NULL;
    ret->receiver = receiver;
    ret->head = ret->tail = NULL;
    ret->writable = 1;		       /* to start with */
    ret->sending_oob = 0;

    /*
     * Open socket.
     */
    s = socket(addr->family, SOCK_STREAM, 0);
    ret->s = s;

    if (s == INVALID_SOCKET) {
	err = WSAGetLastError();
        ret->error = winsock_error_string(err);
	return ret;
    }

    ret->oobinline = oobinline;
    if (oobinline) {
	BOOL b = TRUE;
	setsockopt (s, SOL_SOCKET, SO_OOBINLINE, (void *)&b, sizeof(b));
    }

    /*
     * Bind to local address.
     */
    if (privport)
        localport = 1023;              /* count from 1023 downwards */
    else
        localport = 0;                 /* just use port 0 (ie winsock picks) */

    /* Loop round trying to bind */
    while (1) {
        int retcode;

#ifdef IPV6
        if (addr->family == AF_INET6)
        {
            memset(&a6,0,sizeof(a6));
            a6.sin6_family	= AF_INET6;
            /*a6.sin6_addr	= in6addr_any;*/  /* == 0 */
            a6.sin6_port	= htons(localport);
        }
        else
        {
#endif
            a.sin_family = AF_INET;
            a.sin_addr.s_addr = htonl(INADDR_ANY);
            a.sin_port = htons(localport);
#ifdef IPV6
        }
        retcode = bind (s, (addr->family == AF_INET6 ?
                            (struct sockaddr *)&a6 :
                            (struct sockaddr *)&a),
                        (addr->family == AF_INET6 ? sizeof(a6) : sizeof(a)));
#else
        retcode = bind (s, (struct sockaddr *)&a, sizeof(a));
#endif
        if (retcode != SOCKET_ERROR) {
            err = 0;
            break;                     /* done */
        } else {
            err = WSAGetLastError();
            if (err != WSAEADDRINUSE)  /* failed, for a bad reason */
                break;
        }

        if (localport == 0)
            break;                     /* we're only looping once */
        localport--;
        if (localport == 0)
            break;                     /* we might have got to the end */
    }

    if (err)
    {
	ret->error = winsock_error_string(err);
	return ret;
    }

    /*
     * Connect to remote address.
     */
#ifdef IPV6
    if (addr->family == AF_INET6)
    {
	memset(&a,0,sizeof(a));
	a6.sin6_family = AF_INET6;
	a6.sin6_port = htons((short)port);
	a6.sin6_addr = ((struct sockaddr_in6 *)addr->ai->ai_addr)->sin6_addr;
    }
    else
    {
#endif
	a.sin_family = AF_INET;
	a.sin_addr.s_addr = htonl(addr->address);
	a.sin_port = htons((short)port);
#ifdef IPV6
    }
    if (connect (s, (addr->family == AF_INET6) ? (struct sockaddr *)&a6 : (struct sockaddr *)&a, (addr->family == AF_INET6) ? sizeof(a6) : sizeof(a)) == SOCKET_ERROR)
#else
	if (connect (s, (struct sockaddr *)&a, sizeof(a)) == SOCKET_ERROR)
#endif
    {
	err = WSAGetLastError();
	ret->error = winsock_error_string(err);
	return ret;
    }

    /* Set up a select mechanism. This could be an AsyncSelect on a
     * window, or an EventSelect on an event object. */
    errstr = do_select(s, 1);
    if (errstr) {
	ret->error = errstr;
	return ret;
    }

    add234(sktree, ret);

    return ret;
}

void sk_close(Socket s) {
    extern char *do_select(SOCKET skt, int startup);

    del234(sktree, s);
    do_select(s->s, 0);
    closesocket(s->s);
    sfree(s);
}

/*
 * The function which tries to send on a socket once it's deemed
 * writable.
 */
void try_send(Socket s) {
    while (s->head) {
	int nsent;
	DWORD err;
        int len, urgentflag;

        if (s->sending_oob) {
            urgentflag = MSG_OOB;
            len = s->sending_oob;
        } else {
            urgentflag = 0;
            len = s->head->buflen - s->head->bufpos;
        }

	nsent = send(s->s, s->head->buf + s->head->bufpos, len, urgentflag);
        noise_ultralight(nsent);
	if (nsent <= 0) {
	    err = (nsent < 0 ? WSAGetLastError() : 0);
	    if (err == WSAEWOULDBLOCK) {
		/* Perfectly normal: we've sent all we can for the moment. */
		s->writable = FALSE;
                return;
	    } else if (nsent == 0 ||
		       err == WSAECONNABORTED ||
		       err == WSAECONNRESET) {
                /*
                 * FIXME. This will have to be done better when we
                 * start managing multiple sockets (e.g. SSH port
                 * forwarding), because if we get CONNRESET while
                 * trying to write a particular forwarded socket
                 * then it isn't necessarily the end of the world.
                 * Ideally I'd like to pass the error code back to
                 * somewhere the next select_result() will see it,
                 * but that might be hard. Perhaps I should pass it
                 * back to be queued in the Windows front end bit.
                 */
                fatalbox(winsock_error_string(err));
	    } else {
		fatalbox(winsock_error_string(err));
	    }
	} else {
	    s->head->bufpos += nsent;
            if (s->sending_oob)
                s->sending_oob -= nsent;
	    if (s->head->bufpos >= s->head->buflen) {
		struct buffer *tmp = s->head;
		s->head = tmp->next;
		sfree(tmp);
		if (!s->head)
		    s->tail = NULL;
	    }
	}
    }
}

void sk_write(Socket s, char *buf, int len) {
    /*
     * Add the data to the buffer list on the socket.
     */
    if (s->tail && s->tail->buflen < BUFFER_GRANULE) {
	int copylen = min(len, BUFFER_GRANULE - s->tail->buflen);
	memcpy(s->tail->buf + s->tail->buflen, buf, copylen);
	buf += copylen;
	len -= copylen;
	s->tail->buflen += copylen;
    }
    while (len > 0) {
	int grainlen = min(len, BUFFER_GRANULE);
	struct buffer *newbuf;
	newbuf = smalloc(sizeof(struct buffer));
	newbuf->bufpos = 0;
	newbuf->buflen = grainlen;
	memcpy(newbuf->buf, buf, grainlen);
	buf += grainlen;
	len -= grainlen;
	if (s->tail)
	    s->tail->next = newbuf;
	else
	    s->head = s->tail = newbuf;
	newbuf->next = NULL;
	s->tail = newbuf;
    }

    /*
     * Now try sending from the start of the buffer list.
     */
    if (s->writable)
	try_send(s);
}

void sk_write_oob(Socket s, char *buf, int len) {
    /*
     * Replace the buffer list on the socket with the data.
     */
    if (!s->head) {
	s->head = smalloc(sizeof(struct buffer));
    } else {
        struct buffer *walk = s->head->next;
        while (walk) {
            struct buffer *tmp = walk;
            walk = tmp->next;
            sfree(tmp);
        }
    }
    s->head->next = NULL;
    s->tail = s->head;
    s->head->buflen = len;
    memcpy(s->head->buf, buf, len);

    /*
     * Set the Urgent marker.
     */
    s->sending_oob = len;

    /*
     * Now try sending from the start of the buffer list.
     */
    if (s->writable)
	try_send(s);
}

int select_result(WPARAM wParam, LPARAM lParam) {
    int ret, open;
    DWORD err;
    char buf[BUFFER_GRANULE];
    Socket s;
    u_long atmark;

    /* wParam is the socket itself */
    s = find234(sktree, (void *)wParam, cmpforsearch);
    if (!s)
	return 1;		       /* boggle */

    if ((err = WSAGETSELECTERROR(lParam)) != 0) {
        /*
         * An error has occurred on this socket. Pass it to the
         * receiver function.
         */
        return s->receiver(s, 3, winsock_error_string(err), err);
    }

    noise_ultralight(lParam);

    switch (WSAGETSELECTEVENT(lParam)) {
      case FD_READ:
        /*
         * We have received data on the socket. For an oobinline
         * socket, this might be data _before_ an urgent pointer,
         * in which case we send it to the back end with type==1
         * (data prior to urgent).
         */
        if (s->oobinline) {
            atmark = 1;
            ioctlsocket(s->s, SIOCATMARK, &atmark);
            /*
             * Avoid checking the return value from ioctlsocket(),
             * on the grounds that some WinSock wrappers don't
             * support it. If it does nothing, we get atmark==1,
             * which is equivalent to `no OOB pending', so the
             * effect will be to non-OOB-ify any OOB data.
             */
        } else
            atmark = 1;

	ret = recv(s->s, buf, sizeof(buf), 0);
        noise_ultralight(ret);
	if (ret < 0) {
	    err = WSAGetLastError();
	    if (err == WSAEWOULDBLOCK) {
		break;
	    }
	}
	if (ret < 0) {
	    return s->receiver(s, 3, winsock_error_string(err), err);
	} else {
	    return s->receiver(s, atmark ? 0 : 1, buf, ret);
	}
	break;
      case FD_OOB:
        /*
         * This will only happen on a non-oobinline socket. It
         * indicates that we can immediately perform an OOB read
         * and get back OOB data, which we will send to the back
         * end with type==2 (urgent data).
         */
        ret = recv(s->s, buf, sizeof(buf), MSG_OOB);
        noise_ultralight(ret);
        if (ret <= 0) {
            fatalbox(ret == 0 ? "Internal networking trouble" :
                     winsock_error_string(WSAGetLastError()));
        } else {
            return s->receiver(s, 2, buf, ret);
        }
        break;
      case FD_WRITE:
	s->writable = 1;
	try_send(s);
	break;
      case FD_CLOSE:
	/* Signal a close on the socket. First read any outstanding data. */
        open = 1;
        do {
            ret = recv(s->s, buf, sizeof(buf), 0);
            if (ret < 0) {
                err = WSAGetLastError();
                if (err == WSAEWOULDBLOCK)
                    break;
                return s->receiver(s, 3, winsock_error_string(err), err);
            } else
                open &= s->receiver(s, 0, buf, ret);
	} while (ret > 0);
        return open;
    }

    return 1;
}

/*
 * Each socket abstraction contains a `void *' private field in
 * which the client can keep state.
 */
void sk_set_private_ptr(Socket s, void *ptr) {
    s->private_ptr = ptr;
}
void *sk_get_private_ptr(Socket s) {
    return s->private_ptr;
}

/*
 * Special error values are returned from sk_namelookup and sk_new
 * if there's a problem. These functions extract an error message,
 * or return NULL if there's no problem.
 */
char *sk_addr_error(SockAddr addr) {
    return addr->error;
}
char *sk_socket_error(Socket s) {
    return s->error;
}

/*
 * For Plink: enumerate all sockets currently active.
 */
SOCKET first_socket(enum234 *e) {
    Socket s = first234(sktree, e);
    return s ? s->s : INVALID_SOCKET;
}
SOCKET next_socket(enum234 *e) {
    Socket s = next234(e);
    return s ? s->s : INVALID_SOCKET;
}
Commit	Line	Data
2f75bae1	1	/*
2f75bae1	2	* Windows networking abstraction.
c4d8e107	3	*
	4	* Due to this clean abstraction it was possible
	5	* to easily implement IPv6 support :)
	6	*
	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.
	12	*
	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.
	16	*
	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.
	27	*
	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...
	31	*
2f75bae1	32	*/
2f75bae1	33
c4d8e107	34	/*
	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.
	38	*/
	39	/* #define IPV6 1 */
	40
	41	#ifdef IPV6
	42	#include <winsock2.h>
	43	#include <ws2tcpip.h>
	44	#include <tpipv6.h>
	45	#else
2f75bae1	46	#include <winsock.h>
c4d8e107	47	#endif
c4d8e107	48	#include <windows.h>
2f75bae1	49	#include <stdio.h>
49bad831	50	#include <stdlib.h>
2f75bae1	51
	52	#include "putty.h"
	53	#include "network.h"
	54	#include "tree234.h"
	55
	56	#define BUFFER_GRANULE 512
	57
	58	struct Socket_tag {
	59	char *error;
	60	SOCKET s;
	61	sk_receiver_t receiver;
	62	void *private_ptr;
	63	struct buffer head, tail;
	64	int writable;
1ad4eb6f	65	int sending_oob;
4b1e8acc	66	int oobinline;
2f75bae1	67	};
	68
	69	struct SockAddr_tag {
	70	char *error;
c4d8e107	71	/* address family this belongs to, AF_INET for IPv4, AF_INET6 for IPv6. */
	72	int family;
	73	unsigned long address; /* Address IPv4 style. */
	74	#ifdef IPV6
	75	struct addrinfo ai; / Address IPv6 style. */
	76	#endif
	77	/*
	78	* We need to have this lengthy enough to hold any hostname
	79	* (including IPv6 reverse...)
	80	*/
	81	char realhost[8192];
2f75bae1	82	};
	83
	84	struct buffer {
	85	struct buffer *next;
	86	int buflen, bufpos;
	87	char buf[BUFFER_GRANULE];
	88	};
	89
	90	static tree234 *sktree;
	91
	92	static int cmpfortree(void av, void bv) {
	93	Socket a = (Socket)av, b = (Socket)bv;
	94	unsigned long as = (unsigned long)a->s, bs = (unsigned long)b->s;
	95	if (as < bs) return -1;
	96	if (as > bs) return +1;
	97	return 0;
	98	}
	99
	100	static int cmpforsearch(void av, void bv) {
	101	Socket b = (Socket)bv;
	102	unsigned long as = (unsigned long)av, bs = (unsigned long)b->s;
	103	if (as < bs) return -1;
	104	if (as > bs) return +1;
	105	return 0;
	106	}
	107
	108	void sk_init(void) {
	109	sktree = newtree234(cmpfortree);
	110	}
	111
e74fbad9	112	char *winsock_error_string(int error) {
	113	switch (error) {
	114	case WSAEACCES: return "Network error: Permission denied";
	115	case WSAEADDRINUSE: return "Network error: Address already in use";
	116	case WSAEADDRNOTAVAIL: return "Network error: Cannot assign requested address";
	117	case WSAEAFNOSUPPORT: return "Network error: Address family not supported by protocol family";
	118	case WSAEALREADY: return "Network error: Operation already in progress";
	119	case WSAECONNABORTED: return "Network error: Software caused connection abort";
	120	case WSAECONNREFUSED: return "Network error: Connection refused";
	121	case WSAECONNRESET: return "Network error: Connection reset by peer";
	122	case WSAEDESTADDRREQ: return "Network error: Destination address required";
	123	case WSAEFAULT: return "Network error: Bad address";
	124	case WSAEHOSTDOWN: return "Network error: Host is down";
	125	case WSAEHOSTUNREACH: return "Network error: No route to host";
	126	case WSAEINPROGRESS: return "Network error: Operation now in progress";
	127	case WSAEINTR: return "Network error: Interrupted function call";
	128	case WSAEINVAL: return "Network error: Invalid argument";
	129	case WSAEISCONN: return "Network error: Socket is already connected";
	130	case WSAEMFILE: return "Network error: Too many open files";
	131	case WSAEMSGSIZE: return "Network error: Message too long";
	132	case WSAENETDOWN: return "Network error: Network is down";
	133	case WSAENETRESET: return "Network error: Network dropped connection on reset";
	134	case WSAENETUNREACH: return "Network error: Network is unreachable";
	135	case WSAENOBUFS: return "Network error: No buffer space available";
	136	case WSAENOPROTOOPT: return "Network error: Bad protocol option";
	137	case WSAENOTCONN: return "Network error: Socket is not connected";
	138	case WSAENOTSOCK: return "Network error: Socket operation on non-socket";
	139	case WSAEOPNOTSUPP: return "Network error: Operation not supported";
	140	case WSAEPFNOSUPPORT: return "Network error: Protocol family not supported";
	141	case WSAEPROCLIM: return "Network error: Too many processes";
	142	case WSAEPROTONOSUPPORT: return "Network error: Protocol not supported";
	143	case WSAEPROTOTYPE: return "Network error: Protocol wrong type for socket";
	144	case WSAESHUTDOWN: return "Network error: Cannot send after socket shutdown";
	145	case WSAESOCKTNOSUPPORT: return "Network error: Socket type not supported";
	146	case WSAETIMEDOUT: return "Network error: Connection timed out";
	147	case WSAEWOULDBLOCK: return "Network error: Resource temporarily unavailable";
	148	case WSAEDISCON: return "Network error: Graceful shutdown in progress";
	149	default: return "Unknown network error";
	150	}
	151	}
	152
c4d8e107	153	SockAddr sk_namelookup(char host, char *canonicalname)
c4d8e107	154	{
2f75bae1	155	SockAddr ret = smalloc(sizeof(struct SockAddr_tag));
2f75bae1	156	unsigned long a;
c4d8e107	157	struct hostent *h = NULL;
2f75bae1	158
c4d8e107	159	/* Clear the structure and default to IPv4. */
	160	memset(ret, 0, sizeof(struct SockAddr_tag));
	161	ret->family = 0; /* We set this one when we have resolved the host. */
	162	canonicalname = ret->realhost; / This makes sure we always have a hostname to return. */
	163
	164	if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE)
	165	{
	166	#ifdef IPV6
	167
	168	/* Try to get the getaddrinfo() function from wship6.dll */
	169	/* This way one doesn't need to have IPv6 dll's to use PuTTY and
	170	* it will fallback to IPv4. */
	171	typedef int (CALLBACK* FGETADDRINFO)(const char *nodename,
	172	const char *servname,
	173	const struct addrinfo *hints,
	174	struct addrinfo **res);
	175	FGETADDRINFO fGetAddrInfo = NULL;
	176
	177	HINSTANCE dllWSHIP6 = LoadLibrary("wship6.dll");
	178	if (dllWSHIP6)
	179	fGetAddrInfo = (FGETADDRINFO)GetProcAddress(dllWSHIP6,
	180	"getaddrinfo");
	181
	182	/*
	183	* Use fGetAddrInfo when it's available (which usually also
	184	* means IPv6 is installed...)
	185	*/
	186	if (fGetAddrInfo)
	187	{
	188	/debug(("Resolving \"%s\" with getaddrinfo() (IPv4+IPv6 capable)...\n", host)); /
	189	if (fGetAddrInfo(host, NULL, NULL, &ret->ai) == 0)
	190	ret->family = ret->ai->ai_family;
	191	}
	192	else
	193	#endif
	194	/*
	195	* Otherwise use the IPv4-only gethostbyname...
	196	* (NOTE: we don't use gethostbyname as a
	197	* fallback!)
	198	*/
	199	if (ret->family == 0)
	200	{
	201	/debug(("Resolving \"%s\" with gethostbyname() (IPv4 only)...\n", host)); /
	202	if (h = gethostbyname(host)) ret->family = AF_INET;
	203	}
	204	/debug(("Done resolving...(family is %d) AF_INET = %d, AF_INET6 = %d\n", ret->family, AF_INET, AF_INET6)); /
	205
	206	if (ret->family == 0)
	207	{
2f75bae1	208	DWORD err = WSAGetLastError();
c4d8e107	209	ret->error = (err == WSAENETDOWN ? "Network is down" :
	210	err == WSAHOST_NOT_FOUND ? "Host does not exist" :
	211	err == WSATRY_AGAIN ? "Host not found" :
	212	#ifdef IPV6
	213	fGetAddrInfo ? "getaddrinfo: unknown error" :
	214	#endif
	215	"gethostbyname: unknown error");
	216	#ifdef DEBUG
	217	{
	218	LPVOID lpMsgBuf;
	219	FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER \| FORMAT_MESSAGE_FROM_SYSTEM \| FORMAT_MESSAGE_IGNORE_INSERTS, NULL, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPTSTR)&lpMsgBuf, 0, NULL);
bc51302a	220	/debug(("Error %ld: %s (h=%lx)\n", err, lpMsgBuf, h));/
c4d8e107	221	/* Free the buffer. */
	222	LocalFree(lpMsgBuf);
	223	}
	224	#endif
2f75bae1	225	}
c4d8e107	226	else
	227	{
	228	ret->error = NULL;
	229
	230	#ifdef IPV6
	231	/* If we got an address info use that... */
	232	if (ret->ai)
	233	{
	234	typedef int (CALLBACK* FGETNAMEINFO)
	235	(const struct sockaddr FAR *sa, socklen_t salen,
	236	char FAR * host, size_t hostlen, char FAR * serv,
	237	size_t servlen, int flags);
	238	FGETNAMEINFO fGetNameInfo = NULL;
	239
	240	/* Are we in IPv4 fallback mode? */
	241	/* We put the IPv4 address into the a variable so we can further-on use the IPv4 code... */
	242	if (ret->family == AF_INET)
	243	memcpy(&a, (char )&((SOCKADDR_IN )ret->ai->ai_addr)->sin_addr, sizeof(a));
	244
	245	/* Now let's find that canonicalname... */
	246	if ((dllWSHIP6) && (fGetNameInfo = (FGETNAMEINFO)GetProcAddress(dllWSHIP6, "getnameinfo")))
	247	{
	248	if (fGetNameInfo((struct sockaddr *)ret->ai->ai_addr,
	249	ret->family == AF_INET ?
	250	sizeof(SOCKADDR_IN) :
	251	sizeof(SOCKADDR_IN6), ret->realhost,
	252	sizeof(ret->realhost), NULL,
	253	0, 0) != 0)
	254	{
	255	strncpy(ret->realhost, host,
	256	sizeof(ret->realhost));
	257	}
	258	}
	259	}
	260	/* We used the IPv4-only gethostbyname()... */
	261	else
	262	{
	263	#endif
	264	memcpy(&a, h->h_addr, sizeof(a));
	265	/* This way we are always sure the h->h_name is valid :) */
	266	strncpy(ret->realhost, h->h_name, sizeof(ret->realhost));
	267	#ifdef IPV6
	268	}
	269	#endif
	270	}
	271	#ifdef IPV6
	272	FreeLibrary(dllWSHIP6);
	273	#endif
	274	}
	275	else
	276	{
9d47d0ea	277	/*
	278	* Hack inserted to deal with problems with numeric IPs.
	279	* FIXME: how will this work in IPv6?
	280	*/
	281	ret->family = AF_INET;
2f75bae1	282	*canonicalname = host;
	283	}
	284	ret->address = ntohl(a);
2f75bae1	285	return ret;
	286	}
	287
	288	void sk_addr_free(SockAddr addr) {
	289	sfree(addr);
	290	}
	291
4b1e8acc	292	Socket sk_new(SockAddr addr, int port, int privport, int oobinline,
4b1e8acc	293	sk_receiver_t receiver) {
2f75bae1	294	SOCKET s;
c4d8e107	295	#ifdef IPV6
	296	SOCKADDR_IN6 a6;
	297	#endif
2f75bae1	298	SOCKADDR_IN a;
	299	DWORD err;
	300	char *errstr;
	301	Socket ret;
	302	extern char *do_select(SOCKET skt, int startup);
c91409da	303	short localport;
2f75bae1	304
	305	/*
	306	* Create Socket structure.
	307	*/
	308	ret = smalloc(sizeof(struct Socket_tag));
	309	ret->error = NULL;
	310	ret->receiver = receiver;
	311	ret->head = ret->tail = NULL;
	312	ret->writable = 1; /* to start with */
33232c8f	313	ret->sending_oob = 0;
2f75bae1	314
	315	/*
	316	* Open socket.
	317	*/
c4d8e107	318	s = socket(addr->family, SOCK_STREAM, 0);
2f75bae1	319	ret->s = s;
	320
	321	if (s == INVALID_SOCKET) {
	322	err = WSAGetLastError();
e74fbad9	323	ret->error = winsock_error_string(err);
2f75bae1	324	return ret;
2f75bae1	325	}
4b1e8acc	326
	327	ret->oobinline = oobinline;
	328	if (oobinline) {
1ad4eb6f	329	BOOL b = TRUE;
	330	setsockopt (s, SOL_SOCKET, SO_OOBINLINE, (void *)&b, sizeof(b));
	331	}
2f75bae1	332
	333	/*
	334	* Bind to local address.
	335	*/
c91409da	336	if (privport)
c91409da	337	localport = 1023; /* count from 1023 downwards */
c4d8e107	338	else
c91409da	339	localport = 0; /* just use port 0 (ie winsock picks) */
	340
	341	/* Loop round trying to bind */
	342	while (1) {
	343	int retcode;
	344
	345	#ifdef IPV6
	346	if (addr->family == AF_INET6)
	347	{
	348	memset(&a6,0,sizeof(a6));
	349	a6.sin6_family = AF_INET6;
	350	/a6.sin6_addr = in6addr_any;/ /* == 0 */
	351	a6.sin6_port = htons(localport);
	352	}
	353	else
	354	{
c4d8e107	355	#endif
c91409da	356	a.sin_family = AF_INET;
	357	a.sin_addr.s_addr = htonl(INADDR_ANY);
	358	a.sin_port = htons(localport);
c4d8e107	359	#ifdef IPV6
c91409da	360	}
	361	retcode = bind (s, (addr->family == AF_INET6 ?
	362	(struct sockaddr *)&a6 :
	363	(struct sockaddr *)&a),
	364	(addr->family == AF_INET6 ? sizeof(a6) : sizeof(a)));
c4d8e107	365	#else
c91409da	366	retcode = bind (s, (struct sockaddr *)&a, sizeof(a));
c4d8e107	367	#endif
c91409da	368	if (retcode != SOCKET_ERROR) {
	369	err = 0;
	370	break; /* done */
	371	} else {
	372	err = WSAGetLastError();
	373	if (err != WSAEADDRINUSE) /* failed, for a bad reason */
	374	break;
	375	}
	376
	377	if (localport == 0)
	378	break; /* we're only looping once */
	379	localport--;
	380	if (localport == 0)
	381	break; /* we might have got to the end */
	382	}
	383
	384	if (err)
c4d8e107	385	{
c4d8e107	386	ret->error = winsock_error_string(err);
2f75bae1	387	return ret;
	388	}
	389
	390	/*
	391	* Connect to remote address.
	392	*/
c4d8e107	393	#ifdef IPV6
	394	if (addr->family == AF_INET6)
	395	{
	396	memset(&a,0,sizeof(a));
	397	a6.sin6_family = AF_INET6;
	398	a6.sin6_port = htons((short)port);
	399	a6.sin6_addr = ((struct sockaddr_in6 *)addr->ai->ai_addr)->sin6_addr;
	400	}
	401	else
	402	{
	403	#endif
	404	a.sin_family = AF_INET;
	405	a.sin_addr.s_addr = htonl(addr->address);
	406	a.sin_port = htons((short)port);
	407	#ifdef IPV6
	408	}
	409	if (connect (s, (addr->family == AF_INET6) ? (struct sockaddr )&a6 : (struct sockaddr )&a, (addr->family == AF_INET6) ? sizeof(a6) : sizeof(a)) == SOCKET_ERROR)
	410	#else
	411	if (connect (s, (struct sockaddr *)&a, sizeof(a)) == SOCKET_ERROR)
	412	#endif
	413	{
2f75bae1	414	err = WSAGetLastError();
c4d8e107	415	ret->error = winsock_error_string(err);
2f75bae1	416	return ret;
	417	}
	418
	419	/* Set up a select mechanism. This could be an AsyncSelect on a
	420	* window, or an EventSelect on an event object. */
	421	errstr = do_select(s, 1);
	422	if (errstr) {
	423	ret->error = errstr;
	424	return ret;
	425	}
	426
	427	add234(sktree, ret);
	428
	429	return ret;
	430	}
	431
	432	void sk_close(Socket s) {
9c964e85	433	extern char *do_select(SOCKET skt, int startup);
9c964e85	434
2f75bae1	435	del234(sktree, s);
	436	do_select(s->s, 0);
	437	closesocket(s->s);
dcbde236	438	sfree(s);
2f75bae1	439	}
2f75bae1	440
2f75bae1	441	/*
	442	* The function which tries to send on a socket once it's deemed
	443	* writable.
	444	*/
	445	void try_send(Socket s) {
	446	while (s->head) {
	447	int nsent;
	448	DWORD err;
	449	int len, urgentflag;
	450
	451	if (s->sending_oob) {
	452	urgentflag = MSG_OOB;
	453	len = s->sending_oob;
	454	} else {
	455	urgentflag = 0;
	456	len = s->head->buflen - s->head->bufpos;
	457	}
	458
	459	nsent = send(s->s, s->head->buf + s->head->bufpos, len, urgentflag);
7d6ee6ff	460	noise_ultralight(nsent);
2f75bae1	461	if (nsent <= 0) {
	462	err = (nsent < 0 ? WSAGetLastError() : 0);
	463	if (err == WSAEWOULDBLOCK) {
	464	/* Perfectly normal: we've sent all we can for the moment. */
	465	s->writable = FALSE;
	466	return;
	467	} else if (nsent == 0 \|\|
	468	err == WSAECONNABORTED \|\|
	469	err == WSAECONNRESET) {
	470	/*
	471	* FIXME. This will have to be done better when we
	472	* start managing multiple sockets (e.g. SSH port
	473	* forwarding), because if we get CONNRESET while
	474	* trying to write a particular forwarded socket
	475	* then it isn't necessarily the end of the world.
	476	* Ideally I'd like to pass the error code back to
	477	* somewhere the next select_result() will see it,
	478	* but that might be hard. Perhaps I should pass it
	479	* back to be queued in the Windows front end bit.
	480	*/
	481	fatalbox(winsock_error_string(err));
	482	} else {
	483	fatalbox(winsock_error_string(err));
	484	}
	485	} else {
	486	s->head->bufpos += nsent;
	487	if (s->sending_oob)
	488	s->sending_oob -= nsent;
	489	if (s->head->bufpos >= s->head->buflen) {
	490	struct buffer *tmp = s->head;
	491	s->head = tmp->next;
dcbde236	492	sfree(tmp);
2f75bae1	493	if (!s->head)
	494	s->tail = NULL;
	495	}
	496	}
	497	}
	498	}
	499
	500	void sk_write(Socket s, char *buf, int len) {
	501	/*
	502	* Add the data to the buffer list on the socket.
	503	*/
	504	if (s->tail && s->tail->buflen < BUFFER_GRANULE) {
	505	int copylen = min(len, BUFFER_GRANULE - s->tail->buflen);
	506	memcpy(s->tail->buf + s->tail->buflen, buf, copylen);
	507	buf += copylen;
	508	len -= copylen;
	509	s->tail->buflen += copylen;
	510	}
	511	while (len > 0) {
	512	int grainlen = min(len, BUFFER_GRANULE);
	513	struct buffer *newbuf;
	514	newbuf = smalloc(sizeof(struct buffer));
	515	newbuf->bufpos = 0;
	516	newbuf->buflen = grainlen;
	517	memcpy(newbuf->buf, buf, grainlen);
	518	buf += grainlen;
	519	len -= grainlen;
	520	if (s->tail)
	521	s->tail->next = newbuf;
	522	else
	523	s->head = s->tail = newbuf;
	524	newbuf->next = NULL;
	525	s->tail = newbuf;
	526	}
	527
	528	/*
	529	* Now try sending from the start of the buffer list.
	530	*/
	531	if (s->writable)
	532	try_send(s);
	533	}
	534
	535	void sk_write_oob(Socket s, char *buf, int len) {
	536	/*
	537	* Replace the buffer list on the socket with the data.
	538	*/
	539	if (!s->head) {
	540	s->head = smalloc(sizeof(struct buffer));
	541	} else {
	542	struct buffer *walk = s->head->next;
	543	while (walk) {
	544	struct buffer *tmp = walk;
	545	walk = tmp->next;
dcbde236	546	sfree(tmp);
2f75bae1	547	}
	548	}
	549	s->head->next = NULL;
	550	s->tail = s->head;
	551	s->head->buflen = len;
	552	memcpy(s->head->buf, buf, len);
	553
	554	/*
	555	* Set the Urgent marker.
	556	*/
	557	s->sending_oob = len;
	558
	559	/*
	560	* Now try sending from the start of the buffer list.
	561	*/
	562	if (s->writable)
	563	try_send(s);
	564	}
	565
	566	int select_result(WPARAM wParam, LPARAM lParam) {
f9d3f227	567	int ret, open;
2f75bae1	568	DWORD err;
	569	char buf[BUFFER_GRANULE];
	570	Socket s;
49bad831	571	u_long atmark;
2f75bae1	572
	573	/* wParam is the socket itself */
	574	s = find234(sktree, (void *)wParam, cmpforsearch);
	575	if (!s)
	576	return 1; /* boggle */
	577
	578	if ((err = WSAGETSELECTERROR(lParam)) != 0) {
2c94fd1c	579	/*
	580	* An error has occurred on this socket. Pass it to the
	581	* receiver function.
	582	*/
	583	return s->receiver(s, 3, winsock_error_string(err), err);
2f75bae1	584	}
2f75bae1	585
7d6ee6ff	586	noise_ultralight(lParam);
7d6ee6ff	587
2f75bae1	588	switch (WSAGETSELECTEVENT(lParam)) {
2f75bae1	589	case FD_READ:
4b1e8acc	590	/*
	591	* We have received data on the socket. For an oobinline
	592	* socket, this might be data _before_ an urgent pointer,
	593	* in which case we send it to the back end with type==1
	594	* (data prior to urgent).
	595	*/
	596	if (s->oobinline) {
	597	atmark = 1;
	598	ioctlsocket(s->s, SIOCATMARK, &atmark);
	599	/*
	600	* Avoid checking the return value from ioctlsocket(),
	601	* on the grounds that some WinSock wrappers don't
	602	* support it. If it does nothing, we get atmark==1,
	603	* which is equivalent to `no OOB pending', so the
	604	* effect will be to non-OOB-ify any OOB data.
	605	*/
	606	} else
	607	atmark = 1;
	608
2f75bae1	609	ret = recv(s->s, buf, sizeof(buf), 0);
4b1e8acc	610	noise_ultralight(ret);
2f75bae1	611	if (ret < 0) {
	612	err = WSAGetLastError();
	613	if (err == WSAEWOULDBLOCK) {
	614	break;
	615	}
	616	}
	617	if (ret < 0) {
2c94fd1c	618	return s->receiver(s, 3, winsock_error_string(err), err);
2f75bae1	619	} else {
4b1e8acc	620	return s->receiver(s, atmark ? 0 : 1, buf, ret);
2f75bae1	621	}
	622	break;
	623	case FD_OOB:
4b1e8acc	624	/*
	625	* This will only happen on a non-oobinline socket. It
	626	* indicates that we can immediately perform an OOB read
	627	* and get back OOB data, which we will send to the back
	628	* end with type==2 (urgent data).
	629	*/
2f75bae1	630	ret = recv(s->s, buf, sizeof(buf), MSG_OOB);
7d6ee6ff	631	noise_ultralight(ret);
2f75bae1	632	if (ret <= 0) {
	633	fatalbox(ret == 0 ? "Internal networking trouble" :
	634	winsock_error_string(WSAGetLastError()));
	635	} else {
1ad4eb6f	636	return s->receiver(s, 2, buf, ret);
2f75bae1	637	}
	638	break;
	639	case FD_WRITE:
	640	s->writable = 1;
	641	try_send(s);
	642	break;
	643	case FD_CLOSE:
f9d3f227	644	/* Signal a close on the socket. First read any outstanding data. */
	645	open = 1;
	646	do {
	647	ret = recv(s->s, buf, sizeof(buf), 0);
	648	if (ret < 0) {
	649	err = WSAGetLastError();
	650	if (err == WSAEWOULDBLOCK)
	651	break;
	652	return s->receiver(s, 3, winsock_error_string(err), err);
	653	} else
	654	open &= s->receiver(s, 0, buf, ret);
	655	} while (ret > 0);
	656	return open;
2f75bae1	657	}
	658
	659	return 1;
	660	}
	661
	662	/*
	663	* Each socket abstraction contains a `void *' private field in
	664	* which the client can keep state.
	665	*/
	666	void sk_set_private_ptr(Socket s, void *ptr) {
	667	s->private_ptr = ptr;
	668	}
	669	void *sk_get_private_ptr(Socket s) {
	670	return s->private_ptr;
	671	}
	672
	673	/*
	674	* Special error values are returned from sk_namelookup and sk_new
	675	* if there's a problem. These functions extract an error message,
	676	* or return NULL if there's no problem.
	677	*/
	678	char *sk_addr_error(SockAddr addr) {
	679	return addr->error;
	680	}
	681	char *sk_socket_error(Socket s) {
	682	return s->error;
	683	}
	684
	685	/*
	686	* For Plink: enumerate all sockets currently active.
	687	*/
	688	SOCKET first_socket(enum234 *e) {
	689	Socket s = first234(sktree, e);
	690	return s ? s->s : INVALID_SOCKET;
	691	}
	692	SOCKET next_socket(enum234 *e) {
	693	Socket s = next234(e);
	694	return s ? s->s : INVALID_SOCKET;
	695	}