path: root/WWW/Library/Implementation/HTTCP.c

/*
 * $LynxId: HTTCP.c,v 1.106 2010/11/07 21:20:58 tom Exp $
 *
 *			Generic Communication Code		HTTCP.c
 *			==========================
 *
 *	This code is in common between client and server sides.
 *
 *	16 Jan 92  TBL	Fix strtol() undefined on CMU Mach.
 *	25 Jun 92  JFG	Added DECNET option through TCP socket emulation.
 *	13 Sep 93  MD	Added correct return of vmserrorno for HTInetStatus.
 *			Added decoding of vms error message for MULTINET.
 *	7-DEC-1993 Bjorn S. Nilsson, ALEPH, CERN, VMS UCX ioctl() changes
 *			(done of Mosaic)
 *	19 Feb 94  Danny Mayer	Added Bjorn Fixes to Lynx version
 *	 7 Mar 94  Danny Mayer	Added Fix UCX version for full domain name
 *	20 May 94  Andy Harper	Added support for CMU TCP/IP transport
 *	17 Nov 94  Andy Harper	Added support for SOCKETSHR transport
 *	16 Jul 95  S. Bjorndahl added kluge to deal with LIBCMU bug
 */

#include <HTUtils.h>
#include <HTParse.h>
#include <HTAlert.h>
#include <HTTCP.h>
#include <LYGlobalDefs.h>	/* added for no_suspend */
#include <LYUtils.h>

#ifdef NSL_FORK
#include <signal.h>
#include <www_wait.h>
#endif /* NSL_FORK */

#ifdef HAVE_RESOLV_H
#include <resolv.h>
#endif

#ifdef __DJGPP__
#include <netdb.h>
#endif /* __DJGPP__ */

#define LYNX_ADDRINFO	struct addrinfo
#define LYNX_HOSTENT	struct hostent

#define OK_HOST(p) ((p) != 0 && ((p)->h_length) != 0)

#ifdef SVR4_BSDSELECT
int BSDselect(int nfds,
	      fd_set * readfds,
	      fd_set * writefds,
	      fd_set * exceptfds,
	      struct timeval *select_timeout);

#ifdef select
#undef select
#endif /* select */
#define select BSDselect
#ifdef SOCKS
#ifdef Rselect
#undef Rselect
#endif /* Rselect */
#define Rselect BSDselect
#endif /* SOCKS */
#endif /* SVR4_BSDSELECT */

#include <LYLeaks.h>

/*
 *  Module-Wide variables
 */
static char *hostname = NULL;	/* The name of this host */

/*
 *  PUBLIC VARIABLES
 */
#ifdef SOCKS
unsigned long socks_bind_remoteAddr;	/* for long Rbind */
#endif /* SOCKS */

/*	Encode INET status (as in sys/errno.h)			  inet_status()
 *	------------------
 *
 *  On entry,
 *	where		gives a description of what caused the error
 *	global errno	gives the error number in the Unix way.
 *
 *  On return,
 *	returns		a negative status in the Unix way.
 */

#ifdef DECL_SYS_ERRLIST
extern char *sys_errlist[];	/* see man perror on cernvax */
extern int sys_nerr;
#endif /* DECL_SYS_ERRLIST */

#ifdef __DJGPP__
static int ResolveYield(void)
{
    return HTCheckForInterrupt()? 0 : 1;
}
#endif

#if defined(VMS) && defined(UCX)
/*
 *  A routine to mimic the ioctl function for UCX.
 *  Bjorn S. Nilsson, 25-Nov-1993. Based on an example in the UCX manual.
 */
#include <HTioctl.h>

int HTioctl(int d,
	    int request,
	    int *argp)
{
    int sdc, status;
    unsigned short fun, iosb[4];
    char *p5, *p6;
    struct comm {
	int command;
	char *addr;
    } ioctl_comm;
    struct it2 {
	unsigned short len;
	unsigned short opt;
	struct comm *addr;
    } ioctl_desc;

    if ((sdc = vaxc$get_sdc(d)) == 0) {
	set_errno(EBADF);
	return -1;
    }
    ioctl_desc.opt = UCX$C_IOCTL;
    ioctl_desc.len = sizeof(struct comm);

    ioctl_desc.addr = &ioctl_comm;
    if (request & IOC_OUT) {
	fun = IO$_SENSEMODE;
	p5 = 0;
	p6 = (char *) &ioctl_desc;
    } else {
	fun = IO$_SETMODE;
	p5 = (char *) &ioctl_desc;
	p6 = 0;
    }
    ioctl_comm.command = request;
    ioctl_comm.addr = (char *) argp;
    status = sys$qiow(0, sdc, fun, iosb, 0, 0, 0, 0, 0, 0, p5, p6);
    if (!(status & 01)) {
	set_errno(status);
	return -1;
    }
    if (!(iosb[0] & 01)) {
	set_errno(iosb[0]);
	return -1;
    }
    return 0;
}
#endif /* VMS && UCX */

#define MY_FORMAT "TCP: Error %d in `SOCKET_ERRNO' after call to %s() failed.\n\t%s\n"
	   /* third arg is transport/platform specific */

/*	Report Internet Error
 *	---------------------
 */
int HTInetStatus(const char *where)
{
    int status;
    int saved_errno = errno;

#ifdef VMS
#ifdef MULTINET
    SOCKET_ERRNO = vmserrno;
#endif /* MULTINET */
#endif /* VMS */

#ifdef VM
    CTRACE((tfp, MY_FORMAT, SOCKET_ERRNO, where,
	    "(Error number not translated)"));	/* What Is the VM equiv? */
#define ER_NO_TRANS_DONE
#endif /* VM */

#ifdef VMS
#ifdef MULTINET
    CTRACE((tfp, MY_FORMAT, SOCKET_ERRNO, where,
	    vms_errno_string()));
#else
    CTRACE((tfp, MY_FORMAT, SOCKET_ERRNO, where,
	    ((SOCKET_ERRNO > 0 && SOCKET_ERRNO <= 65) ?
	     strerror(SOCKET_ERRNO) : "(Error number not translated)")));
#endif /* MULTINET */
#define ER_NO_TRANS_DONE
#endif /* VMS */

#ifdef HAVE_STRERROR
    CTRACE((tfp, MY_FORMAT, SOCKET_ERRNO, where,
	    strerror(SOCKET_ERRNO)));
#define ER_NO_TRANS_DONE
#endif /* HAVE_STRERROR */

#ifndef ER_NO_TRANS_DONE
    CTRACE((tfp, MY_FORMAT, SOCKET_ERRNO, where,
	    (SOCKET_ERRNO < sys_nerr ?
	     sys_errlist[SOCKET_ERRNO] : "Unknown error")));
#endif /* !ER_NO_TRANS_DONE */

#ifdef VMS
#ifndef MULTINET
    CTRACE((tfp,
	    "         Unix error number (SOCKET_ERRNO) = %ld dec\n",
	    SOCKET_ERRNO));
    CTRACE((tfp,
	    "         VMS error (vaxc$errno)    = %lx hex\n",
	    vaxc$errno));
#endif /* MULTINET */
#endif /* VMS */

    set_errno(saved_errno);

#ifdef VMS
    /*
     * uerrno and errno happen to be zero if vmserrno <> 0
     */
#ifdef MULTINET
    status = -vmserrno;
#else
    status = -vaxc$errno;
#endif /* MULTINET */
#else
    status = -SOCKET_ERRNO;
#endif /* VMS */
    return status;
}

/*	Parse a cardinal value				       parse_cardinal()
 *	----------------------
 *
 * On entry,
 *	*pp	    points to first character to be interpreted, terminated by
 *		    non 0:9 character.
 *	*pstatus    points to status already valid
 *	maxvalue    gives the largest allowable value.
 *
 * On exit,
 *	*pp	    points to first unread character
 *	*pstatus    points to status updated iff bad
 */
unsigned int HTCardinal(int *pstatus,
			char **pp,
			unsigned int max_value)
{
    unsigned int n;

    if ((**pp < '0') || (**pp > '9')) {		/* Null string is error */
	*pstatus = -3;		/* No number where one expected */
	return 0;
    }

    n = 0;
    while ((**pp >= '0') && (**pp <= '9'))
	n = n * 10 + (unsigned) (*((*pp)++) - '0');

    if (n > max_value) {
	*pstatus = -4;		/* Cardinal outside range */
	return 0;
    }

    return n;
}

#ifndef DECNET			/* Function only used below for a trace message */
/*	Produce a string for an Internet address
 *	----------------------------------------
 *
 *  On exit,
 *	returns a pointer to a static string which must be copied if
 *		it is to be kept.
 */
const char *HTInetString(SockA * soc_in)
{
#ifdef INET6
    static char hostbuf[MAXHOSTNAMELEN];

    getnameinfo((struct sockaddr *) soc_in,
		SOCKADDR_LEN(soc_in),
		hostbuf, (socklen_t) sizeof(hostbuf),
		NULL, 0,
		NI_NUMERICHOST);
    return hostbuf;
#else
    static char string[20];

    sprintf(string, "%d.%d.%d.%d",
	    (int) *((unsigned char *) (&soc_in->sin_addr) + 0),
	    (int) *((unsigned char *) (&soc_in->sin_addr) + 1),
	    (int) *((unsigned char *) (&soc_in->sin_addr) + 2),
	    (int) *((unsigned char *) (&soc_in->sin_addr) + 3));
    return string;
#endif /* INET6 */
}
#endif /* !DECNET */

/*	Check whether string is a valid Internet hostname - kw
 *	-------------------------------------------------
 *
 *  Checks whether
 *  - contains only valid chars for domain names (actually, the
 *    restrictions are somewhat relaxed),
 *  - no leading dots or empty segments,
 *  - no segment starts with '-' or '+' [this protects telnet command],
 *  - max. length of dot-separated segment <= 63 (RFC 1034,1035),
 *  - total length <= 254 (if it ends with dot) or 253 (otherwise)
 *     [an interpretation of RFC 1034,1035, although RFC 1123
 *      suggests 255 as limit - kw].
 *
 *  Note: user (before '@') and port (after ':') components from
 *      host part of URL should be already stripped (if appropriate)
 *      from the input string.
 *
 *  On exit,
 *	returns 1 if valid, otherwise 0.
 */
BOOL valid_hostname(char *name)
{
    int i = 1, iseg = 0;
    char *cp = name;

    if (!(name && *name))
	return NO;
    for (; (*cp && i <= 253); cp++, i++) {
	if (*cp == '.') {
	    if (iseg == 0) {
		return NO;
	    } else {
		iseg = 0;
		continue;
	    }
	} else if (iseg == 0 && (*cp == '-' || *cp == '+')) {
	    return NO;
	} else if (++iseg > 63) {
	    return NO;
	}
	if (!isalnum(UCH(*cp)) &&
	    *cp != '-' && *cp != '_' &&
	    *cp != '$' && *cp != '+') {
	    return NO;
	}
    }
    return (BOOL) (*cp == '\0' || (*cp == '.' && iseg != 0 && cp[1] == '\0'));
}

#ifdef NSL_FORK
/*
 *  Function to allow us to be killed with a normal signal (not
 *  SIGKILL), but don't go through normal libc exit() processing, which
 *  would screw up parent's stdio.  -BL
 */
static void quench(int sig GCC_UNUSED)
{
    _exit(2);
}
#endif /* NSL_FORK */

int lynx_nsl_status = HT_OK;

#define DEBUG_HOSTENT		/* disable in case of problems */
#define DEBUG_HOSTENT_CHILD	/* for NSL_FORK, may screw up trace file */

/*
 *  Two auxiliary functions for name lookup and LYNX_HOSTENT.
 *
 *  dump_hostent - dumps the contents of a LYNX_HOSTENT to the
 *  trace log or stderr, including all pointer values, strings, and
 *  addresses, in a format inspired by gdb's print format. - kw
 */
static void dump_hostent(const char *msgprefix,
			 const LYNX_HOSTENT *phost)
{
    if (TRACE) {
	int i;
	char **pcnt;

	CTRACE((tfp, "%s: %p ", msgprefix, (const void *) phost));
	if (phost) {
	    CTRACE((tfp, "{ h_name = %p", phost->h_name));
	    if (phost->h_name) {
		CTRACE((tfp, " \"%s\",", phost->h_name));
	    } else {
		CTRACE((tfp, ","));
	    }
	    CTRACE((tfp, "\n\t h_aliases = %p", (void *) phost->h_aliases));
	    if (phost->h_aliases) {
		CTRACE((tfp, " {"));
		for (pcnt = phost->h_aliases; *pcnt; pcnt++) {
		    CTRACE((tfp, "%s %p \"%s\"",
			    (pcnt == phost->h_aliases ? " " : ", "),
			    *pcnt, *pcnt));
		}
		CTRACE((tfp, "%s0x0 },\n\t",
			(*phost->h_aliases ? ", " : " ")));
	    } else {
		CTRACE((tfp, ",\n\t"));
	    }
	    CTRACE((tfp, " h_addrtype = %d,", phost->h_addrtype));
	    CTRACE((tfp, " h_length = %d,\n\t", phost->h_length));
	    CTRACE((tfp, " h_addr_list = %p", (void *) phost->h_addr_list));
	    if (phost->h_addr_list) {
		CTRACE((tfp, " {"));
		for (pcnt = phost->h_addr_list; *pcnt; pcnt++) {
		    CTRACE((tfp, "%s %p",
			    (pcnt == phost->h_addr_list ? "" : ","),
			    *pcnt));
		    for (i = 0; i < phost->h_length; i++) {
			CTRACE((tfp, "%s%d%s", (i == 0 ? " \"" : "."),
				(int) *((unsigned char *) (*pcnt) + i),
				(i + 1 == phost->h_length ? "\"" : "")));
		    }
		}
		if (*phost->h_addr_list) {
		    CTRACE((tfp, ", 0x0 } }"));
		} else {
		    CTRACE((tfp, " 0x0 } }"));
		}
	    } else {
		CTRACE((tfp, "}"));
	    }
	}
	CTRACE((tfp, "\n"));
	fflush(tfp);
    }
}

/*
 *  fill_rehostent - copies as much as possible relevant content from
 *  the LYNX_HOSTENT pointed to by phost to the char buffer given
 *  by rehostent, subject to maximum output length rehostentsize,
 *  following pointers and building self-contained output which can be
 *  cast to a LYNX_HOSTENT. - kw
 *  See also description of LYGetHostByName.
 */
#if defined(NSL_FORK) || defined(_WINDOWS_NSL)

#define REHOSTENT_SIZE 128	/* not bigger than pipe buffer! */

typedef struct {
    LYNX_HOSTENT h;
    char rest[REHOSTENT_SIZE];
} AlignedHOSTENT;

static size_t fill_rehostent(char *rehostent,
			     size_t rehostentsize,
			     const LYNX_HOSTENT *phost)
{
    AlignedHOSTENT *data = (AlignedHOSTENT *) rehostent;
    int num_addrs = 0;
    int num_aliases = 0;
    char **pcnt;
    char *p_next_char;
    char **p_next_charptr;
    size_t name_len = 0;
    size_t required_per_addr;
    size_t curlen = sizeof(LYNX_HOSTENT);
    size_t available = rehostentsize - curlen;
    size_t chk_available, mem_this_alias, required_this_alias;
    int i_addr, i_alias;

    if (!phost)
	return 0;
    required_per_addr = (size_t) phost->h_length + sizeof(char *);

    if (phost->h_addr_list)
	available -= sizeof(phost->h_addr_list[0]);
    if (phost->h_aliases)
	available -= sizeof(phost->h_aliases[0]);
    if (phost->h_name)
	available--;
    if (phost->h_addr_list) {
	if (phost->h_addr_list[0]) {
	    if (available >= required_per_addr) {
		num_addrs++;
		available -= required_per_addr;
	    }
	}
    }
    if (phost->h_name) {
	name_len = strlen(phost->h_name);
	if (available >= name_len) {
	    available -= name_len;
	} else {
	    name_len = 0;
	}
    }
    if (num_addrs) {
	for (pcnt = phost->h_addr_list + 1; *pcnt; pcnt++) {
	    if (available >= required_per_addr) {
		num_addrs++;
		available -= required_per_addr;
	    } else {
		break;
	    }
	}
    }
    chk_available = available;
    if (phost->h_aliases) {
	for (pcnt = phost->h_aliases; *pcnt; pcnt++) {
	    required_this_alias = sizeof(phost->h_aliases[0]) +
		strlen(*pcnt) + 1;
	    if (chk_available >= required_this_alias) {
		num_aliases++;
		chk_available -= required_this_alias;
	    }
	}
    }

    data->h.h_addrtype = phost->h_addrtype;
    data->h.h_length = phost->h_length;
    p_next_charptr = (char **) (rehostent + curlen);
    p_next_char = rehostent + curlen;
    if (phost->h_addr_list)
	p_next_char += (size_t) (num_addrs + 1) * sizeof(phost->h_addr_list[0]);
    if (phost->h_aliases)
	p_next_char += (size_t) (num_aliases + 1) * sizeof(phost->h_aliases[0]);

    if (phost->h_addr_list) {
	data->h.h_addr_list = p_next_charptr;
	for (pcnt = phost->h_addr_list, i_addr = 0;
	     i_addr < num_addrs;
	     pcnt++, i_addr++) {
	    MemCpy(p_next_char, *pcnt, sizeof(phost->h_addr_list[0]));
	    *p_next_charptr++ = p_next_char;
	    p_next_char += sizeof(phost->h_addr_list[0]);
	}
	*p_next_charptr = NULL;
    } else {
	data->h.h_addr_list = NULL;
    }

    if (phost->h_name) {
	data->h.h_name = p_next_char;
	if (name_len) {
	    strcpy(p_next_char, phost->h_name);
	    p_next_char += name_len + 1;
	} else {
	    *p_next_char++ = '\0';
	}
    } else {
	data->h.h_name = NULL;
    }

    if (phost->h_aliases) {
	data->h.h_aliases = p_next_charptr;
	for (pcnt = phost->h_aliases, i_alias = 0;
	     (*pcnt && i_alias < num_addrs);
	     pcnt++, i_alias++) {
	    mem_this_alias = strlen(*pcnt) + 1;
	    required_this_alias = sizeof(phost->h_aliases[0]) +
		mem_this_alias;
	    if (available >= required_this_alias) {
		i_alias++;
		available -= required_this_alias;
		strcpy(p_next_char, *pcnt);
		*p_next_charptr++ = p_next_char;
		p_next_char += mem_this_alias;
	    }
	    p_next_char += sizeof(phost->h_aliases[0]);
	}
	*p_next_charptr = NULL;
    } else {
	data->h.h_aliases = NULL;
    }
    curlen = (size_t) (p_next_char - (char *) rehostent);
    return curlen;
}

/*
 * This chunk of code is used in both win32 and cygwin.
 */
#if defined(_WINDOWS_NSL)
static LYNX_HOSTENT *gbl_phost;	/* Pointer to host - See netdb.h */

#if !(defined(__CYGWIN__) && defined(NSL_FORK))
static int donelookup;

static unsigned long __stdcall _fork_func(void *arg)
{
    const char *host = (const char *) arg;
    static AlignedHOSTENT aligned_full_rehostent;
    char *rehostent = (char *) &aligned_full_rehostent;
    size_t rehostentlen = 0;

#ifdef SH_EX
    unsigned long addr;

    addr = (unsigned long) inet_addr(host);
    if (addr != INADDR_NONE)
	gbl_phost = gethostbyaddr((char *) &addr, sizeof(addr), AF_INET);
    else
	gbl_phost = gethostbyname(host);
#else
    gbl_phost = gethostbyname(host);
#endif

    if (gbl_phost) {
	rehostentlen = fill_rehostent(rehostent,
				      (size_t) REHOSTENT_SIZE,
				      gbl_phost);
	if (rehostentlen == 0) {
	    gbl_phost = (LYNX_HOSTENT *) NULL;
	} else {
	    gbl_phost = (LYNX_HOSTENT *) rehostent;
	}
    }

    donelookup = TRUE;
    return (unsigned long) (gbl_phost);
}
#endif /* __CYGWIN__ */
#endif /* _WINDOWS_NSL */
#endif /* NSL_FORK */

#ifndef HAVE_H_ERRNO
#undef  h_errno
#define h_errno my_errno
static int my_errno;

#else /* we do HAVE_H_ERRNO: */
#ifndef h_errno			/* there may be a macro as well as the extern data */
extern int h_errno;
#endif
#endif

/*
 * Even though it is a small amount, we cannot count on reading the whole
 * struct via a pipe in one read -TD
 */
#ifdef NSL_FORK
static unsigned readit(int fd, char *buffer, size_t length)
{
    unsigned result = 0;

    while (length != 0) {
	unsigned got = (unsigned) read(fd, buffer, length);

	if ((int) got > 0) {
	    result += got;
	    buffer += got;
	    length -= got;
	} else {
	    break;
	}
    }
    return result;
}
#endif /* NSL_FORK */

/*	Resolve an internet hostname, like gethostbyname
 *	------------------------------------------------
 *
 *  On entry,
 *	str	points to the given host name, not numeric address,
 *		without colon or port number.
 *
 *  On exit,
 *	returns a pointer to a LYNX_HOSTENT in static storage,
 *	or NULL in case of error or user interruption.
 *
 *  The interface is intended to be exactly the same as for (Unix)
 *  gethostbyname(), except for the following:
 *
 *  If NSL_FORK is not used, the result of gethostbyname is returned
 *  directly.  Otherwise:
 *  All lists, addresses, and strings referred to by pointers in the
 *  returned struct are located, together with the returned struct
 *  itself, in a buffer of size REHOSTENT_SIZE.  If not everything fits,
 *  some info is omitted, but the function is careful to still return
 *  a valid structure, without truncating strings; it tries to return,
 *  in order of decreasing priority, the first address (h_addr_list[0]), the
 *  official name (h_name), the additional addresses, then alias names.
 *
 *  If NULL is returned, the reason is made available in the global
 *  variable lynx_nsl_status, with one of the following values:
 *	HT_INTERRUPTED		Interrupted by user
 *	HT_NOT_ACCEPTABLE	Hostname detected as invalid
 *				(also sets h_errno)
 *	HT_H_ERRNO_VALID	An error occurred, and h_errno holds
 *				an appropriate value
 *	HT_ERROR		Resolver error, reason not known
 *	HT_INTERNAL		Internal error
 */
LYNX_HOSTENT *LYGetHostByName(char *str)
{
    char *host = str;

#ifdef NSL_FORK
    /* for transfer of result between from child to parent: */
    static AlignedHOSTENT aligned_full_rehostent;

    /*
     * We could define rehosten directly as a static char
     * rehostent[REHOSTENT_SIZE], but the indirect approach via the above
     * struct should automatically take care of alignment requirements.
     * Note that, in addition,
     * - this must be static, as we shall return a pointer to it which must
     *   remain valid, and
     * - we have to use the same rehostent in the child process as in the
     *   parent (its address in the parent's address space must be the same as
     *   in the child's, otherwise the internal pointers built by the child's
     *   call to fill_rehostent would be invalid when seen by the parent).  -kw
     */
    char *rehostent = (char *) &aligned_full_rehostent;

    /* for transfer of status from child to parent: */
    struct _statuses {
	size_t rehostentlen;
	int h_length;
	int child_errno;	/* sometimes useful to pass this on */
	int child_h_errno;
	BOOL h_errno_valid;
    } statuses;

    size_t rehostentlen = 0;
#endif /* NSL_FORK */

    LYNX_HOSTENT *result_phost = NULL;

#ifdef __DJGPP__
    _resolve_hook = ResolveYield;
#endif

    if (!str) {
	CTRACE((tfp, "LYGetHostByName: Can't parse `NULL'.\n"));
	lynx_nsl_status = HT_INTERNAL;
	return NULL;
    }
    CTRACE((tfp, "LYGetHostByName: parsing `%s'.\n", str));

    /*  Could disable this if all our callers already check - kw */
    if (HTCheckForInterrupt()) {
	CTRACE((tfp, "LYGetHostByName: INTERRUPTED for '%s'.\n", str));
	lynx_nsl_status = HT_INTERRUPTED;
	return NULL;
    }

    if (!valid_hostname(host)) {
	lynx_nsl_status = HT_NOT_ACCEPTABLE;
#ifdef NO_RECOVERY
#ifdef _WINDOWS
	WSASetLastError(NO_RECOVERY);
#else
	h_errno = NO_RECOVERY;
#endif
#endif
	return NULL;
    }
#ifdef MVS			/* Outstanding problem with crash in MVS gethostbyname */
    CTRACE((tfp, "LYGetHostByName: Calling gethostbyname(%s)\n", host));
#endif /* MVS */

    CTRACE_FLUSH(tfp);		/* so child messages will not mess up parent log */

    lynx_nsl_status = HT_INTERNAL;	/* should be set to something else below */

#ifdef NSL_FORK
    statuses.h_errno_valid = NO;
    /*
     * Start block for fork-based gethostbyname() with checks for interrupts.
     * - Tom Zerucha (tz@execpc.com) & FM
     */
    {
	int got_rehostent = 0;

#if HAVE_SIGACTION
	sigset_t old_sigset;
	sigset_t new_sigset;
#endif
	/*
	 * Pipe, child pid, status buffers, start time, select() control
	 * variables.
	 */
	int fpid, waitret;
	int pfd[2], selret;
	unsigned readret;

#ifdef HAVE_TYPE_UNIONWAIT
	union wait waitstat;

#else
	int waitstat = 0;
#endif
	time_t start_time = time((time_t *) 0);
	fd_set readfds;
	struct timeval one_second;
	long dns_patience = 30;	/* how many seconds will we wait for DNS? */
	int child_exited = 0;

	/*
	 * Reap any children that have terminated since last time through.
	 * This might include children that we killed, then waited with WNOHANG
	 * before they were actually ready to be reaped.  (Should be max of 1
	 * in this state, but the loop is safe if waitpid() is implemented
	 * correctly:  returns 0 when children exist but none have exited; -1
	 * with errno == ECHILD when no children.) -BL
	 */
	do {
	    waitret = waitpid(-1, 0, WNOHANG);
	} while (waitret > 0 || (waitret == -1 && errno == EINTR));
	waitret = 0;

	IGNORE_RC(pipe(pfd));

#if HAVE_SIGACTION
	/*
	 * Attempt to prevent a rare situation where the child could execute
	 * the Lynx signal handlers because it gets killed before it even has a
	 * chance to reset its handlers, resulting in bogus 'Exiting via
	 * interrupt' message and screen corruption or worse.
	 * Should that continue to be reported, for systems without
	 * sigprocmask(), we need to find a different solutions for those.  -
	 * kw 19990430
	 */
	sigemptyset(&new_sigset);
	sigaddset(&new_sigset, SIGTERM);
	sigaddset(&new_sigset, SIGINT);
#ifndef NOSIGHUP
	sigaddset(&new_sigset, SIGHUP);
#endif /* NOSIGHUP */
#ifdef SIGTSTP
	sigaddset(&new_sigset, SIGTSTP);
#endif /* SIGTSTP */
#ifdef SIGWINCH
	sigaddset(&new_sigset, SIGWINCH);
#endif /* SIGWINCH */
	sigprocmask(SIG_BLOCK, &new_sigset, &old_sigset);
#endif /* HAVE_SIGACTION */

	if ((fpid = fork()) == 0) {
	    LYNX_HOSTENT *phost;	/* Pointer to host - See netdb.h */

	    /*
	     * Child - for the long call.
	     *
	     * Make sure parent can kill us at will.  -BL
	     */
	    (void) signal(SIGTERM, quench);

	    /*
	     * Also make sure the child does not run one of the signal handlers
	     * that may have been installed by Lynx if one of those signals
	     * occurs.  For example we don't want the child to remove temp
	     * files on ^C, let the parent deal with that.  - kw
	     */
	    (void) signal(SIGINT, quench);
#ifndef NOSIGHUP
	    (void) signal(SIGHUP, quench);
#endif /* NOSIGHUP */
#ifdef SIGTSTP
	    if (no_suspend)
		(void) signal(SIGTSTP, SIG_IGN);
	    else
		(void) signal(SIGTSTP, SIG_DFL);
#endif /* SIGTSTP */
#ifdef SIGWINCH
	    (void) signal(SIGWINCH, SIG_IGN);
#endif /* SIGWINCH */
#ifndef __linux__
#ifndef DOSPATH
	    signal(SIGBUS, SIG_DFL);
#endif /* DOSPATH */
#endif /* !__linux__ */
	    signal(SIGSEGV, SIG_DFL);
	    signal(SIGILL, SIG_DFL);

#if HAVE_SIGACTION
	    /* Restore signal mask to whatever it was before the fork. -kw */
	    sigprocmask(SIG_SETMASK, &old_sigset, NULL);
#endif /* HAVE_SIGACTION */

	    /*
	     * Child won't use read side.  -BL
	     */
	    close(pfd[0]);
#ifdef HAVE_H_ERRNO
	    /* to detect cases when it doesn't get set although it should */
	    h_errno = -2;
#endif
	    set_errno(0);
	    phost = gethostbyname(host);
	    statuses.child_errno = errno;
	    statuses.child_h_errno = h_errno;
#ifdef HAVE_H_ERRNO
	    statuses.h_errno_valid = YES;
#endif
#ifdef MVS
	    CTRACE((tfp, "LYGetHostByName: gethostbyname() returned %d\n", phost));
#endif /* MVS */

#ifdef DEBUG_HOSTENT_CHILD
	    dump_hostent("CHILD gethostbyname", phost);
#endif
	    if (OK_HOST(phost)) {
		rehostentlen = fill_rehostent(rehostent,
					      (size_t) REHOSTENT_SIZE,
					      phost);
#ifdef DEBUG_HOSTENT_CHILD
		dump_hostent("CHILD fill_rehostent", (LYNX_HOSTENT *) rehostent);
#endif
	    }
	    if (rehostentlen <= sizeof(LYNX_HOSTENT) ||
		!OK_HOST((LYNX_HOSTENT *) rehostent)) {
		rehostentlen = 0;
		statuses.h_length = 0;
	    } else {
		statuses.h_length = ((LYNX_HOSTENT *) rehostent)->h_length;
#ifdef HAVE_H_ERRNO
		if (h_errno == -2)	/* success, but h_errno unchanged? */
		    statuses.h_errno_valid = NO;
#endif
	    }
	    /*
	     * Send variables indicating status of lookup to parent.  That
	     * includes rehostentlen, which the parent will use as the size for
	     * the second read (if > 0).
	     */
	    if (!statuses.child_errno)
		statuses.child_errno = errno;
	    statuses.rehostentlen = rehostentlen;
	    IGNORE_RC(write(pfd[1], &statuses, sizeof(statuses)));

	    if (rehostentlen) {
		/*
		 * Return our resulting rehostent through pipe...
		 */
		IGNORE_RC(write(pfd[1], rehostent, rehostentlen));
		close(pfd[1]);
		_exit(0);
	    } else {
		/*
		 * ...  or return error as exit code.
		 */
		_exit(1);
	    }
	}
#if HAVE_SIGACTION
	/*
	 * (parent) Restore signal mask to whatever it was before the fork.  -
	 * kw
	 */
	sigprocmask(SIG_SETMASK, &old_sigset, NULL);
#endif /* HAVE_SIGACTION */

	/*
	 * (parent) Wait until lookup finishes, or interrupt, or cycled too
	 * many times (just in case) -BL
	 */

	close(pfd[1]);		/* parent won't use write side -BL */

	if (fpid < 0) {		/* fork failed */
	    close(pfd[0]);
	    goto failed;
	}

	while (child_exited || (long) (time((time_t *) 0) - start_time) < dns_patience) {

	    FD_ZERO(&readfds);
	    /*
	     * This allows us to abort immediately, not after 1-second timeout,
	     * when user hits abort key.  Can't do this when using SLANG (or at
	     * least I don't know how), so SLANG users must live with up-to-1s
	     * timeout.  -BL
	     *
	     * Whoops -- we need to make sure stdin is actually selectable!
	     * /dev/null isn't, on some systems, which makes some useful Lynx
	     * invocations fail.  -BL
	     */
	    {
		int kbd_fd = LYConsoleInputFD(TRUE);

		if (kbd_fd != INVSOC) {
		    FD_SET(kbd_fd, &readfds);
		}
	    }

	    one_second.tv_sec = 1;
	    one_second.tv_usec = 0;
	    FD_SET(pfd[0], &readfds);

	    /*
	     * Return when data received, interrupted, or failed.  If nothing
	     * is waiting, we sleep for 1 second in select(), to be nice to the
	     * system.  -BL
	     */
#ifdef SOCKS
	    if (socks_flag)
		selret = Rselect(pfd[0] + 1, &readfds, NULL, NULL, &one_second);
	    else
#endif /* SOCKS */
		selret = select(pfd[0] + 1, &readfds, NULL, NULL, &one_second);

	    if ((selret > 0) && FD_ISSET(pfd[0], &readfds)) {
		/*
		 * First get status, including length of address.  -BL, kw
		 */
		readret = readit(pfd[0], (char *) &statuses, sizeof(statuses));
		if (readret == sizeof(statuses)) {
		    h_errno = statuses.child_h_errno;
		    set_errno(statuses.child_errno);
#ifdef HAVE_H_ERRNO
		    if (statuses.h_errno_valid) {
			lynx_nsl_status = HT_H_ERRNO_VALID;
			/*
			 * If something went wrong in the child process other
			 * than normal lookup errors, and it appears that we
			 * have enough info to know what went wrong, generate
			 * diagnostic output.  ENOMEM observed on linux in
			 * processes constrained with ulimit.  It would be too
			 * unkind to abort the session, access to local files
			 * or through a proxy may still work.  - kw
			 */
			if (
#ifdef NETDB_INTERNAL		/* linux glibc: defined in netdb.h */
			       (errno && h_errno == NETDB_INTERNAL) ||
#endif
			       (errno == ENOMEM &&
				statuses.rehostentlen == 0 &&
			/* should probably be NETDB_INTERNAL if child
			   memory exhausted, but we may find that
			   h_errno remains unchanged. - kw */
				h_errno == -2)) {
#ifndef MULTINET
			    HTInetStatus("CHILD gethostbyname");
#endif
			    HTAlert(LYStrerror(statuses.child_errno));
			    if (errno == ENOMEM) {
				/*
				 * Not much point in continuing, right?  Fake a
				 * 'z', should shorten pointless guessing
				 * cycle.  - kw
				 */
				LYFakeZap(YES);
			    }
			}
		    }
#endif /* HAVE_H_ERRNO */
		    if (statuses.rehostentlen > sizeof(LYNX_HOSTENT)) {
			/*
			 * Then get the full reorganized hostent.  -BL, kw
			 */
			readret = readit(pfd[0], rehostent, statuses.rehostentlen);
#ifdef DEBUG_HOSTENT
			dump_hostent("Read from pipe", (LYNX_HOSTENT *) rehostent);
#endif
			if (readret == statuses.rehostentlen) {
			    got_rehostent = 1;
			    result_phost = (LYNX_HOSTENT *) rehostent;
			    lynx_nsl_status = HT_OK;
			} else if (!statuses.h_errno_valid) {
			    lynx_nsl_status = HT_INTERNAL;
			}
		    }
		} else {
		    lynx_nsl_status = HT_ERROR;
		}
		/*
		 * Make sure child is cleaned up.  -BL
		 */
		if (!child_exited)
		    waitret = waitpid(fpid, &waitstat, WNOHANG);
		if (!WIFEXITED(waitstat) && !WIFSIGNALED(waitstat)) {
		    kill(fpid, SIGTERM);
		    waitret = waitpid(fpid, &waitstat, WNOHANG);
		}
		break;
	    }

	    /*
	     * Clean up if child exited before & no data received.  -BL
	     */
	    if (child_exited) {
		waitret = waitpid(fpid, &waitstat, WNOHANG);
		break;
	    }
	    /*
	     * If child exited, loop once more looking for data.  -BL
	     */
	    if ((waitret = waitpid(fpid, &waitstat, WNOHANG)) > 0) {
		/*
		 * Data will be arriving right now, so make sure we don't
		 * short-circuit out for too many loops, and skip the interrupt
		 * check.  -BL
		 */
		child_exited = 1;
		continue;
	    }

	    /*
	     * Abort if interrupt key pressed.
	     */
	    if (HTCheckForInterrupt()) {
		CTRACE((tfp, "LYGetHostByName: INTERRUPTED gethostbyname.\n"));
		kill(fpid, SIGTERM);
		waitpid(fpid, NULL, WNOHANG);
		close(pfd[0]);
		lynx_nsl_status = HT_INTERRUPTED;
		return NULL;
	    }
	}
	close(pfd[0]);
	if (waitret <= 0) {
	    kill(fpid, SIGTERM);
	    waitret = waitpid(fpid, &waitstat, WNOHANG);
	}
	if (waitret > 0) {
	    if (WIFEXITED(waitstat)) {
		CTRACE((tfp,
			"LYGetHostByName: NSL_FORK child %d exited, status 0x%x.\n",
			(int) waitret, WEXITSTATUS(waitstat)));
	    } else if (WIFSIGNALED(waitstat)) {
		CTRACE((tfp,
			"LYGetHostByName: NSL_FORK child %d got signal, status 0x%x!\n",
			(int) waitret, WTERMSIG(waitstat)));
#ifdef WCOREDUMP
		if (WCOREDUMP(waitstat)) {
		    CTRACE((tfp,
			    "LYGetHostByName: NSL_FORK child %d dumped core!\n",
			    (int) waitret));
		}
#endif /* WCOREDUMP */
	    } else if (WIFSTOPPED(waitstat)) {
		CTRACE((tfp,
			"LYGetHostByName: NSL_FORK child %d is stopped, status 0x%x!\n",
			(int) waitret, WSTOPSIG(waitstat)));
	    }
	}
	if (!got_rehostent) {
	    goto failed;
	}
    }
#else /* Not NSL_FORK: */

#ifdef _WINDOWS_NSL
    {
	HANDLE hThread;
	DWORD dwThreadID;

#ifndef __CYGWIN__
	if (!system_is_NT) {	/* for Windows9x */
	    unsigned long t;

	    t = (unsigned long) inet_addr(host);
	    if (t != INADDR_NONE)
		gbl_phost = gethostbyaddr((char *) &t, sizeof(t), AF_INET);
	    else
		gbl_phost = gethostbyname(host);
	} else {		/* for Windows NT */
#endif /* !__CYGWIN__ */
	    gbl_phost = (LYNX_HOSTENT *) NULL;
	    donelookup = FALSE;

#if defined(__CYGWIN__) || defined(USE_WINSOCK2_H)
	    SetLastError(WSAHOST_NOT_FOUND);
#else
	    WSASetLastError(WSAHOST_NOT_FOUND);
#endif

	    hThread = CreateThread(NULL, 4096UL, _fork_func, host, 0UL,
				   &dwThreadID);
	    if (!hThread)
		MessageBox(NULL, "CreateThread",
			   "CreateThread Failed", 0L);

	    while (!donelookup) {
		if (HTCheckForInterrupt()) {
		    /* Note that host is a character array and is not freed */
		    /* to avoid possible subthread problems: */
		    if (!CloseHandle(hThread)) {
			MessageBox((void *) NULL,
				   "CloseHandle", "CloseHandle Failed", 0L);
		    }
		    lynx_nsl_status = HT_INTERRUPTED;
		    return NULL;
		}
	    }
#ifndef __CYGWIN__
	}
#endif /* !__CYGWIN__ */
	if (gbl_phost) {
	    lynx_nsl_status = HT_OK;
	    result_phost = gbl_phost;
	} else {
	    lynx_nsl_status = HT_ERROR;
	    goto failed;
	}
    }

#else /* !NSL_FORK, !_WINDOWS_NSL: */
    {
	LYNX_HOSTENT *phost;

	phost = gethostbyname(host);	/* See netdb.h */
#ifdef MVS
	CTRACE((tfp, "LYGetHostByName: gethostbyname() returned %d\n", phost));
#endif /* MVS */
	if (phost) {
	    lynx_nsl_status = HT_OK;
	    result_phost = phost;
	} else {
	    lynx_nsl_status = HT_H_ERRNO_VALID;
	    goto failed;
	}
    }
#endif /* !NSL_FORK, !_WINDOWS_NSL */
#endif /* !NSL_FORK */

#ifdef DEBUG_HOSTENT
    dump_hostent("End of LYGetHostByName", result_phost);
    CTRACE((tfp, "LYGetHostByName: Resolved name to a hostent.\n"));
#endif

    return result_phost;	/* OK */

  failed:
    CTRACE((tfp, "LYGetHostByName: Can't find internet node name `%s'.\n",
	    host));
    return NULL;
}

/*	Parse a network node address and port
 *	-------------------------------------
 *
 *  On entry,
 *	str	points to a string with a node name or number,
 *		with optional trailing colon and port number.
 *	soc_in	points to the binary internet or decnet address field.
 *
 *  On exit,
 *	*soc_in is filled in.  If no port is specified in str, that
 *		field is left unchanged in *soc_in.
 */
#ifndef INET6
static int HTParseInet(SockA * soc_in, const char *str)
{
    char *port;
    int dotcount_ip = 0;	/* for dotted decimal IP addr */
    char *strptr;
    char *host = NULL;

    if (!str) {
	CTRACE((tfp, "HTParseInet: Can't parse `NULL'.\n"));
	return -1;
    }
    CTRACE((tfp, "HTParseInet: parsing `%s'.\n", str));
    if (HTCheckForInterrupt()) {
	CTRACE((tfp, "HTParseInet: INTERRUPTED for '%s'.\n", str));
	return -1;
    }
    StrAllocCopy(host, str);	/* Make a copy we can mutilate */
    /*
     * Parse port number if present.
     */
    if ((port = strchr(host, ':')) != NULL) {
	*port++ = 0;		/* Chop off port */
	strptr = port;
	if (port[0] >= '0' && port[0] <= '9') {
#ifdef UNIX
	    soc_in->sin_port = (PortNumber) htons(strtol(port, &strptr, 10));
#else /* VMS: */
#ifdef DECNET
	    soc_in->sdn_objnum = (unsigned char) (strtol(port, &strptr, 10));
#else
	    soc_in->sin_port = htons((PortNumber) strtol(port, &strptr, 10));
#endif /* Decnet */
#endif /* Unix vs. VMS */
#ifdef SUPPRESS			/* 1. crashes!?!.  2. URL syntax has number not name */
	} else {
	    struct servent *serv = getservbyname(port, (char *) 0);

	    if (serv) {
		soc_in->sin_port = serv->s_port;
	    } else {
		CTRACE((tfp, "TCP: Unknown service %s\n", port));
	    }
#endif /* SUPPRESS */
	}
	if (strptr && *strptr != '\0') {
	    FREE(host);
	    HTAlwaysAlert(NULL, gettext("Address has invalid port"));
	    return -1;
	}
    }
#ifdef DECNET
    /*
     * Read Decnet node name.  @@ Should know about DECnet addresses, but it's
     * probably worth waiting until the Phase transition from IV to V.
     */
    soc_in->sdn_nam.n_len = min(DN_MAXNAML, strlen(host));	/* <=6 in phase 4 */
    StrNCpy(soc_in->sdn_nam.n_name, host, soc_in->sdn_nam.n_len + 1);
    CTRACE((tfp,
	    "DECnet: Parsed address as object number %d on host %.6s...\n",
	    soc_in->sdn_objnum, host));
#else /* parse Internet host: */

    if (*host >= '0' && *host <= '9') {		/* Test for numeric node address: */
	strptr = host;
	while (*strptr) {
	    if (*strptr == '.') {
		dotcount_ip++;
	    } else if (!isdigit(UCH(*strptr))) {
		break;
	    }
	    strptr++;
	}
	if (*strptr) {		/* found non-numeric, assume domain name */
	    dotcount_ip = 0;
	}
    }

    /*
     * Parse host number if present.
     */
    if (dotcount_ip == 3)	/* Numeric node address: */
    {
#ifdef DGUX_OLD
	soc_in->sin_addr.s_addr = inet_addr(host).s_addr;	/* See arpa/inet.h */
#else
#ifdef GUSI
	soc_in->sin_addr = inet_addr(host);	/* See netinet/in.h */
#else
#ifdef HAVE_INET_ATON
	if (!inet_aton(host, &(soc_in->sin_addr))) {
	    CTRACE((tfp, "inet_aton(%s) returns error\n", host));
	    FREE(host);
	    return -1;
	}
#else
	soc_in->sin_addr.s_addr = inet_addr(host);	/* See arpa/inet.h */
#endif /* HAVE_INET_ATON */
#endif /* GUSI */
#endif /* DGUX_OLD */
	FREE(host);
    } else {			/* Alphanumeric node name: */

#ifdef MVS			/* Outstanding problem with crash in MVS gethostbyname */
	CTRACE((tfp, "HTParseInet: Calling LYGetHostByName(%s)\n", host));
#endif /* MVS */

#ifdef _WINDOWS_NSL
	gbl_phost = LYGetHostByName(host);	/* See above */
	if (!gbl_phost)
	    goto failed;
	MemCpy((void *) &soc_in->sin_addr, gbl_phost->h_addr_list[0], gbl_phost->h_length);
#else /* !_WINDOWS_NSL */
	{
	    LYNX_HOSTENT *phost;

	    phost = LYGetHostByName(host);	/* See above */

	    if (!phost)
		goto failed;
	    if (!phost)
		goto failed;
	    if (phost->h_length != sizeof soc_in->sin_addr) {
		HTAlwaysAlert(host, gettext("Address length looks invalid"));
	    }
	    MemCpy((void *) &soc_in->sin_addr, phost->h_addr_list[0], phost->h_length);
	}
#endif /* _WINDOWS_NSL */

	FREE(host);
    }				/* Alphanumeric node name */

    CTRACE((tfp,
	    "HTParseInet: Parsed address as port %d, IP address %d.%d.%d.%d\n",
	    (int) ntohs(soc_in->sin_port),
	    (int) *((unsigned char *) (&soc_in->sin_addr) + 0),
	    (int) *((unsigned char *) (&soc_in->sin_addr) + 1),
	    (int) *((unsigned char *) (&soc_in->sin_addr) + 2),
	    (int) *((unsigned char *) (&soc_in->sin_addr) + 3)));
#endif /* Internet vs. Decnet */

    return 0;			/* OK */

  failed:
    CTRACE((tfp, "HTParseInet: Can't find internet node name `%s'.\n",
	    host));
    FREE(host);
    switch (lynx_nsl_status) {
    case HT_NOT_ACCEPTABLE:
    case HT_INTERRUPTED:
	return lynx_nsl_status;
    default:
	return -1;
    }
}
#endif /* !INET6 */

#ifdef INET6
static LYNX_ADDRINFO *HTGetAddrInfo(const char *str,
				    const int defport)
{
    LYNX_ADDRINFO hints, *res;
    int error;
    char *p;
    char *s = NULL;
    char *host, *port;
    char pbuf[80];

    StrAllocCopy(s, str);

    if (s[0] == '[' && (p = strchr(s, ']')) != NULL) {
	*p++ = '\0';
	host = s + 1;
    } else {
	p = s;
	host = &s[0];
    }
    port = strrchr(p, ':');
    if (port) {
	*port++ = '\0';
    } else {
	sprintf(pbuf, "%d", defport);
	port = pbuf;
    }

    memset(&hints, 0, sizeof(hints));
    hints.ai_family = PF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    error = getaddrinfo(host, port, &hints, &res);
    if (error || !res) {
	CTRACE((tfp, "HTGetAddrInfo: getaddrinfo(%s, %s): %s\n", host, port,
		gai_strerror(error)));
	res = NULL;
    }

    free(s);
    return res;
}
#endif /* INET6 */

#ifdef LY_FIND_LEAKS
/*	Free our name for the host on which we are - FM
 *	-------------------------------------------
 *
 */
static void free_HTTCP_hostname(void)
{
    FREE(hostname);
}
#endif /* LY_FIND_LEAKS */

/*	Derive the name of the host on which we are
 *	-------------------------------------------
 *
 */
static void get_host_details(void)
{
    char name[MAXHOSTNAMELEN + 1];	/* The name of this host */

#ifdef UCX
    char *domain_name;		/* The name of this host domain */
#endif /* UCX */
#ifdef NEED_HOST_ADDRESS	/* no -- needs name server! */
#ifdef INET6
    LYNX_ADDRINFO hints, *res;
    int error;

#else
    LYNX_HOSTENT *phost;	/* Pointer to host -- See netdb.h */
#endif /* INET6 */
#endif /* NEED_HOST_ADDRESS */
    size_t namelength = sizeof(name);

    if (hostname)
	return;			/* Already done */
    gethostname(name, namelength);	/* Without domain */
    StrAllocCopy(hostname, name);
#ifdef LY_FIND_LEAKS
    atexit(free_HTTCP_hostname);
#endif
#ifdef UCX
    /*
     * UCX doesn't give the complete domain name.  Get rest from UCX$BIND_DOM
     * logical.
     */
    if (strchr(hostname, '.') == NULL) {	/* Not full address */
	domain_name = LYGetEnv("UCX$BIND_DOMAIN");
	if (domain_name == NULL)
	    domain_name = LYGetEnv("TCPIP$BIND_DOMAIN");
	if (domain_name != NULL) {
	    StrAllocCat(hostname, ".");
	    StrAllocCat(hostname, domain_name);
	}
    }
#endif /* UCX */
    CTRACE((tfp, "TCP: Local host name is %s\n", hostname));

#ifndef DECNET			/* Decnet ain't got no damn name server 8#OO */
#ifdef NEED_HOST_ADDRESS	/* no -- needs name server! */
#ifdef INET6
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = PF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_CANONNAME;
    error = getaddrinfo(name, NULL, &hints, &res);
    if (error || !res || !res->ai_canonname) {
	CTRACE((tfp, "TCP: %s: `%s'\n", gai_strerror(error), name));
	if (res)
	    freeaddrinfo(res);
	return;			/* Fail! */
    }
    StrAllocCopy(hostname, res->ai_canonname);
    MemCpy(&HTHostAddress, res->ai_addr, res->ai_addrlen);
    freeaddrinfo(res);
#else
    phost = gethostbyname(name);	/* See netdb.h */
    if (!OK_HOST(phost)) {
	CTRACE((tfp,
		"TCP: Can't find my own internet node address for `%s'!!\n",
		name));
	return;			/* Fail! */
    }
    StrAllocCopy(hostname, phost->h_name);
    MemCpy(&HTHostAddress, &phost->h_addr_list[0], phost->h_length);
#endif /* INET6 */
    CTRACE((tfp, "     Name server says that I am `%s' = %s\n",
	    hostname, HTInetString(&HTHostAddress)));
#endif /* NEED_HOST_ADDRESS */

#endif /* !DECNET */
}

const char *HTHostName(void)
{
    get_host_details();
    return hostname;
}

#ifdef _WINDOWS
#define SET_EINTR WSASetLastError(EINTR)
#else
#define SET_EINTR SOCKET_ERRNO = EINTR
#endif

static BOOL HTWasInterrupted(int *status)
{
    BOOL result = FALSE;

    if (HTCheckForInterrupt()) {
	result = TRUE;
	*status = HT_INTERRUPTED;
	SET_EINTR;
    }
    return result;
}

#define TRIES_PER_SECOND 10

/*
 * Set the select-timeout to 0.1 seconds.
 */
static void set_timeout(struct timeval *timeoutp)
{
    timeoutp->tv_sec = 0;
    timeoutp->tv_usec = 100000;
}

#ifndef MULTINET		/* SOCKET_ERRNO != errno ? */
#if !defined(UCX) || !defined(VAXC)	/* errno not modifiable ? */
#define SOCKET_DEBUG_TRACE	/* show errno status after some system calls */
#endif /* UCX && VAXC */
#endif /* MULTINET */
/*
 *  Interruptible connect as implemented for Mosaic by Marc Andreesen
 *  and hacked in for Lynx years ago by Lou Montulli, and further
 *  modified over the years by numerous Lynx lovers. - FM
 */
int HTDoConnect(const char *url,
		const char *protocol,
		int default_port,
		int *s)
{
    int status = 0;
    char *line = NULL;
    char *p1 = NULL;
    char *at_sign = NULL;
    char *host = NULL;

#ifdef INET6
    LYNX_ADDRINFO *res = 0, *res0 = 0;

#else
    struct sockaddr_in soc_address;
    struct sockaddr_in *soc_in = &soc_address;

    /*
     * Set up defaults.
     */
    memset(soc_in, 0, sizeof(*soc_in));
    soc_in->sin_family = AF_INET;
    soc_in->sin_port = htons((PortNumber) default_port);
#endif /* INET6 */

    /*
     * Get node name and optional port number.
     */
    p1 = HTParse(url, "", PARSE_HOST);
    if ((at_sign = strchr(p1, '@')) != NULL) {
	/*
	 * If there's an @ then use the stuff after it as a hostname.
	 */
	StrAllocCopy(host, (at_sign + 1));
    } else {
	StrAllocCopy(host, p1);
    }
    FREE(p1);

    HTSprintf0(&line, "%s%s", WWW_FIND_MESSAGE, host);
    _HTProgress(line);
#ifdef INET6
    /* HTParseInet() is useless! */
    res0 = HTGetAddrInfo(host, default_port);
    if (res0 == NULL) {
	HTSprintf0(&line, gettext("Unable to locate remote host %s."), host);
	_HTProgress(line);
	FREE(host);
	FREE(line);
	return HT_NO_DATA;
    }
#else
    status = HTParseInet(soc_in, host);
    if (status) {
	if (status != HT_INTERRUPTED) {
	    if (status == HT_NOT_ACCEPTABLE) {
		/* Not HTProgress, so warning won't be overwritten immediately;
		 * but not HTAlert, because typically there will be other
		 * alerts from the callers.  - kw
		 */
		HTUserMsg2(gettext("Invalid hostname %s"), host);
	    } else {
		HTSprintf0(&line,
			   gettext("Unable to locate remote host %s."), host);
		_HTProgress(line);
	    }
	    status = HT_NO_DATA;
	}
	FREE(host);
	FREE(line);
	return status;
    }
#endif /* INET6 */

    HTSprintf0(&line, gettext("Making %s connection to %s"), protocol, host);
    _HTProgress(line);
    FREE(host);
    FREE(line);

    /*
     * Now, let's get a socket set up from the server for the data.
     */
#ifndef INET6
    *s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (*s == -1) {
	HTAlert(gettext("socket failed."));
	return HT_NO_DATA;
    }
#else
    for (res = res0; res; res = res->ai_next) {
	*s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
	if (*s == -1) {
	    char hostbuf[1024], portbuf[1024];

	    getnameinfo(res->ai_addr, res->ai_addrlen,
			hostbuf, (socklen_t) sizeof(hostbuf),
			portbuf, (socklen_t) sizeof(portbuf),
			NI_NUMERICHOST | NI_NUMERICSERV);
	    HTSprintf0(&line,
		       gettext("socket failed: family %d addr %s port %s."),
		       res->ai_family, hostbuf, portbuf);
	    _HTProgress(line);
	    FREE(line);
	    continue;
	}
#endif /* INET6 */

#if !defined(DOSPATH) || defined(__DJGPP__)
#if !defined(NO_IOCTL) || defined(USE_FCNTL)
	/*
	 * Make the socket non-blocking, so the connect can be canceled.  This
	 * means that when we issue the connect we should NOT have to wait for
	 * the accept on the other end.
	 */
	{
#ifdef USE_FCNTL
	    int ret = fcntl(*s, F_SETFL, O_NONBLOCK);

#else
	    int val = 1;
	    int ret = IOCTL(*s, FIONBIO, &val);
#endif /* USE_FCNTL */
	    if (ret == -1)
		_HTProgress(gettext("Could not make connection non-blocking."));
	}
#endif /* !NO_IOCTL || USE_FCNTL */
#endif /* !DOSPATH || __DJGPP__ */

	/*
	 * Issue the connect.  Since the server can't do an instantaneous
	 * accept and we are non-blocking, this will almost certainly return a
	 * negative status.
	 */
#ifdef SOCKS
	if (socks_flag) {
#ifdef INET6
	    status = Rconnect(*s, res->ai_addr, res->ai_addrlen);
#else
	    status = Rconnect(*s, (struct sockaddr *) &soc_address,
			      sizeof(soc_address));
#ifndef SHORTENED_RBIND
	    socks_bind_remoteAddr = soc_address.sin_addr.s_addr;
#endif
#endif /* INET6 */
	} else
#endif /* SOCKS */
#ifdef INET6
	    status = connect(*s, res->ai_addr, res->ai_addrlen);
#else
	    status = connect(*s, (struct sockaddr *) &soc_address, sizeof(soc_address));
#endif /* INET6 */

	/*
	 * According to the Sun man page for connect:
	 *  EINPROGRESS         The socket is non-blocking and the  con-
	 *                      nection cannot be completed immediately.
	 *                      It is possible to select(2) for  comple-
	 *                      tion  by  selecting the socket for writ-
	 *                      ing.
	 * According to the Motorola SVR4 man page for connect:
	 *  EAGAIN              The socket is non-blocking and the  con-
	 *                      nection cannot be completed immediately.
	 *                      It is possible to select for  completion
	 *                      by  selecting  the  socket  for writing.
	 *                      However, this is only  possible  if  the
	 *                      socket  STREAMS  module  is  the topmost
	 *                      module on  the  protocol  stack  with  a
	 *                      write  service  procedure.  This will be
	 *                      the normal case.
	 */
	if ((status < 0) &&
	    (SOCKET_ERRNO == EINPROGRESS
#ifdef EAGAIN
	     || SOCKET_ERRNO == EAGAIN
#endif
	    )) {
	    struct timeval select_timeout;
	    int ret;
	    int tries = 0;

#ifdef SOCKET_DEBUG_TRACE
	    HTInetStatus("this socket's first connect");
#endif /* SOCKET_DEBUG_TRACE */
	    ret = 0;
	    while (ret <= 0) {
		fd_set writefds;

		/*
		 * Protect against an infinite loop.
		 */
		if ((tries++ / TRIES_PER_SECOND) >= connect_timeout) {
		    HTAlert(gettext("Connection failed (too many retries)."));
#ifdef INET6
		    FREE(line);
		    if (res0)
			freeaddrinfo(res0);
#endif /* INET6 */
		    return HT_NO_DATA;
		}
		set_timeout(&select_timeout);
		FD_ZERO(&writefds);
		FD_SET((unsigned) *s, &writefds);
#ifdef SOCKS
		if (socks_flag)
		    ret = Rselect(*s + 1, NULL,
				  &writefds, NULL, &select_timeout);
		else
#endif /* SOCKS */
		    ret = select(*s + 1,
				 NULL,
				 &writefds,
				 NULL,
				 &select_timeout);

#ifdef SOCKET_DEBUG_TRACE
		if (tries == 1) {
		    HTInetStatus("this socket's first select");
		}
#endif /* SOCKET_DEBUG_TRACE */
		/*
		 * If we suspend, then it is possible that select will be
		 * interrupted.  Allow for this possibility.  - JED
		 */
		if ((ret == -1) && (errno == EINTR))
		    continue;

#ifdef SOCKET_DEBUG_TRACE
		if (ret < 0) {
		    HTInetStatus("failed select");
		}
#endif /* SOCKET_DEBUG_TRACE */
		/*
		 * Again according to the Sun and Motorola man pages for
		 * connect:
		 *  EALREADY    The socket is non-blocking and a  previ-
		 *              ous  connection attempt has not yet been
		 *              completed.
		 * Thus if the SOCKET_ERRNO is NOT EALREADY we have a real
		 * error, and should break out here and return that error.
		 * Otherwise if it is EALREADY keep on trying to complete the
		 * connection.
		 */
		if ((ret < 0) && (SOCKET_ERRNO != EALREADY)) {
		    status = ret;
		    break;
		} else if (ret > 0) {
		    /*
		     * Extra check here for connection success, if we try to
		     * connect again, and get EISCONN, it means we have a
		     * successful connection.  But don't check with SOCKS.
		     */
#ifdef SOCKS
		    if (socks_flag) {
			status = 0;
		    } else {
#endif /* SOCKS */
#ifdef INET6
			status = connect(*s, res->ai_addr, res->ai_addrlen);
#else
			status = connect(*s, (struct sockaddr *) &soc_address,
					 sizeof(soc_address));
#endif /* INET6 */
#ifdef UCX
			/*
			 * A UCX feature:  Instead of returning EISCONN UCX
			 * returns EADDRINUSE.  Test for this status also.
			 */
			if ((status < 0) && ((SOCKET_ERRNO == EISCONN) ||
					     (SOCKET_ERRNO == EADDRINUSE)))
#else
			if ((status < 0) && (SOCKET_ERRNO == EISCONN))
#endif /* UCX */
			{
			    status = 0;
			}

			if (status && (SOCKET_ERRNO == EALREADY))	/* new stuff LJM */
			    ret = 0;	/* keep going */
			else {
#ifdef SOCKET_DEBUG_TRACE
			    if (status < 0) {
				HTInetStatus("confirm-ready connect");
			    }
#endif /* SOCKET_DEBUG_TRACE */
			    break;
			}
#ifdef SOCKS
		    }
#endif /* SOCKS */
		}
#ifdef SOCKS
		else if (!socks_flag)
#else
		else
#endif /* SOCKS */
		{
		    /*
		     * The select says we aren't ready yet.  Try to connect
		     * again to make sure.  If we don't get EALREADY or
		     * EISCONN, something has gone wrong.  Break out and report
		     * it.
		     *
		     * For some reason, SVR4 returns EAGAIN here instead of
		     * EALREADY, even though the man page says it should be
		     * EALREADY.
		     *
		     * For some reason, UCX pre 3 apparently returns errno =
		     * 18242 instead of EALREADY or EISCONN.
		     */
#ifdef INET6
		    status = connect(*s, res->ai_addr, res->ai_addrlen);
#else
		    status = connect(*s, (struct sockaddr *) &soc_address,
				     sizeof(soc_address));
#endif /* INET6 */
		    if ((status < 0) &&
			(SOCKET_ERRNO != EALREADY
#ifdef EAGAIN
			 && SOCKET_ERRNO != EAGAIN
#endif
			) &&
#ifdef UCX
			(SOCKET_ERRNO != 18242) &&
#endif /* UCX */
			(SOCKET_ERRNO != EISCONN)) {
#ifdef SOCKET_DEBUG_TRACE
			HTInetStatus("confirm-not-ready connect");
#endif /* SOCKET_DEBUG_TRACE */
			break;
		    }
		}
		if (HTWasInterrupted(&status)) {
		    CTRACE((tfp, "*** INTERRUPTED in middle of connect.\n"));
		    break;
		}
	    }
	}
#ifdef SOCKET_DEBUG_TRACE
	else if (status < 0) {
	    HTInetStatus("this socket's first and only connect");
	}
#endif /* SOCKET_DEBUG_TRACE */
#ifdef INET6
	if (status < 0) {
	    NETCLOSE(*s);
	    *s = -1;
	    continue;
	}
	break;
    }
#endif /* INET6 */

#ifdef INET6
    if (*s < 0)
#else
    if (status < 0)
#endif /* INET6 */
    {
	/*
	 * The connect attempt failed or was interrupted, so close up the
	 * socket.
	 */
	NETCLOSE(*s);
    }
#if !defined(DOSPATH) || defined(__DJGPP__)
#if !defined(NO_IOCTL) || defined(USE_FCNTL)
    else {
	/*
	 * Make the socket blocking again on good connect.
	 */
#ifdef USE_FCNTL
	int ret = fcntl(*s, F_SETFL, 0);

#else
	int val = 0;
	int ret = IOCTL(*s, FIONBIO, &val);
#endif /* USE_FCNTL */
	if (ret == -1)
	    _HTProgress(gettext("Could not restore socket to blocking."));
    }
#endif /* !NO_IOCTL || USE_FCNTL */
#endif /* !DOSPATH || __DJGPP__ */

#ifdef INET6
    FREE(line);
    if (res0)
	freeaddrinfo(res0);
#endif /* INET6 */
    return status;
}

/*
 *  This is so interruptible reads can be implemented cleanly.
 */
int HTDoRead(int fildes,
	     void *buf,
	     unsigned nbyte)
{
    int result;
    BOOL ready;

#if !defined(NO_IOCTL)
    int ret;
    fd_set readfds;
    struct timeval select_timeout;
    int tries = 0;

#ifdef USE_READPROGRESS
    int otries = 0;
    time_t otime = time((time_t *) 0);
    time_t start = otime;
#endif
#endif /* !NO_IOCTL */

#if defined(UNIX) && !defined(__BEOS__)
    if (fildes == 0) {
	/*
	 * 0 can be a valid socket fd, but if it's a tty something must have
	 * gone wrong.  - kw
	 */
	if (isatty(fildes)) {
	    CTRACE((tfp, "HTDoRead - refusing to read fd 0 which is a tty!\n"));
	    return -1;
	}
    } else
#endif
    if (fildes <= 0) {
	CTRACE((tfp, "HTDoRead - no file descriptor!\n"));
	return -1;
    }

    if (HTWasInterrupted(&result)) {
	CTRACE((tfp, "HTDoRead - interrupted before starting!\n"));
	return (result);
    }
#if defined(NO_IOCTL)
    ready = TRUE;
#else
    ready = FALSE;
    while (!ready) {
	/*
	 * Protect against an infinite loop.
	 */
	if ((tries++ / TRIES_PER_SECOND) >= reading_timeout) {
	    HTAlert(gettext("Socket read failed (too many tries)."));
	    SET_EINTR;
	    result = HT_INTERRUPTED;
	    break;
	}
#ifdef USE_READPROGRESS
	if (tries - otries > TRIES_PER_SECOND) {
	    time_t t = time((time_t *) 0);

	    otries = tries;
	    if (t - otime >= 5) {
		otime = t;
		HTReadProgress((off_t) (-1), (off_t) 0);	/* Put "stalled" message */
	    }
	}
#endif

	/*
	 * If we suspend, then it is possible that select will be interrupted.
	 * Allow for this possibility.  - JED
	 */
	do {
	    set_timeout(&select_timeout);
	    FD_ZERO(&readfds);
	    FD_SET((unsigned) fildes, &readfds);
#ifdef SOCKS
	    if (socks_flag)
		ret = Rselect(fildes + 1,
			      &readfds, NULL, NULL, &select_timeout);
	    else
#endif /* SOCKS */
		ret = select(fildes + 1,
			     &readfds, NULL, NULL, &select_timeout);
	} while ((ret == -1) && (errno == EINTR));

	if (ret < 0) {
	    result = -1;
	    break;
	} else if (ret > 0) {
	    ready = TRUE;
	} else if (HTWasInterrupted(&result)) {
	    break;
	}
    }
#endif /* !NO_IOCTL */

    if (ready) {
#if defined(UCX) && defined(VAXC)
	/*
	 * VAXC and UCX problem only.
	 */
	errno = vaxc$errno = 0;
	result = SOCKET_READ(fildes, buf, nbyte);
	CTRACE((tfp,
		"Read - result,errno,vaxc$errno: %d %d %d\n", result, errno, vaxc$errno));
	if ((result <= 0) && TRACE)
	    perror("HTTCP.C:HTDoRead:read");	/* RJF */
	/*
	 * An errno value of EPIPE and result < 0 indicates end-of-file on VAXC.
	 */
	if ((result <= 0) && (errno == EPIPE)) {
	    result = 0;
	    set_errno(0);
	}
#else
#ifdef UNIX
	while ((result = (int) SOCKET_READ(fildes, buf, nbyte)) == -1) {
	    if (errno == EINTR)
		continue;
#ifdef ERESTARTSYS
	    if (errno == ERESTARTSYS)
		continue;
#endif /* ERESTARTSYS */
	    HTInetStatus("read");
	    break;
	}
#else /* UNIX */
	result = SOCKET_READ(fildes, buf, nbyte);
#endif /* !UNIX */
#endif /* UCX && VAXC */
    }
#ifdef USE_READPROGRESS
    CTRACE2(TRACE_TIMING, (tfp, "...HTDoRead returns %d (%" PRI_time_t
			   " seconds)\n",
			   result, CAST_time_t (time((time_t *)0) - start)));
#endif
    return result;
}

#ifdef SVR4_BSDSELECT
/*
 *  This is a fix for the difference between BSD's select() and
 *  SVR4's select().  SVR4's select() can never return a value larger
 *  than the total number of file descriptors being checked.  So, if
 *  you select for read and write on one file descriptor, and both
 *  are true, SVR4 select() will only return 1.  BSD select in the
 *  same situation will return 2.
 *
 *	Additionally, BSD select() on timing out, will zero the masks,
 *	while SVR4 does not.  This is fixed here as well.
 *
 *	Set your tabstops to 4 characters to have this code nicely formatted.
 *
 *	Jerry Whelan, guru@bradley.edu, June 12th, 1993
 */
#ifdef select
#undef select
#endif /* select */

#ifdef SOCKS
#ifdef Rselect
#undef Rselect
#endif /* Rselect */
#endif /* SOCKS */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/select.h>

int BSDselect(int nfds,
	      fd_set * readfds,
	      fd_set * writefds,
	      fd_set * exceptfds,
	      struct timeval *select_timeout)
{
    int rval, i;

#ifdef SOCKS
    if (socks_flag)
	rval = Rselect(nfds, readfds, writefds, exceptfds, select_timeout);
    else
#endif /* SOCKS */
	rval = select(nfds, readfds, writefds, exceptfds, select_timeout);

    switch (rval) {
    case -1:
	return (rval);

    case 0:
	if (readfds != NULL)
	    FD_ZERO(readfds);
	if (writefds != NULL)
	    FD_ZERO(writefds);
	if (exceptfds != NULL)
	    FD_ZERO(exceptfds);
	return (rval);

    default:
	for (i = 0, rval = 0; i < nfds; i++) {
	    if ((readfds != NULL) && FD_ISSET(i, readfds))
		rval++;
	    if ((writefds != NULL) && FD_ISSET(i, writefds))
		rval++;
	    if ((exceptfds != NULL) && FD_ISSET(i, exceptfds))
		rval++;

	}
	return (rval);
    }
/* Should never get here */
}
#endif /* SVR4_BSDSELECT */