tcp_unix.c

这是用C编写IMAP源代码

/*
 * Program:	UNIX TCP/IP routines
 *
 * Author:	Mark Crispin
 *		Networks and Distributed Computing
 *		Computing & Communications
 *		University of Washington
 *		Administration Building, AG-44
 *		Seattle, WA  98195
 *		Internet: [e-mail]
 *
 * Date:	1 August 1988
 * Last Edited:	8 August 2005
 * 
 * The IMAP toolkit provided in this Distribution is
 * Copyright 1988-2005 University of Washington.
 * The full text of our legal notices is contained in the file called
 * CPYRIGHT, included with this Distribution.
 */

#include "ip_unix.c"

#undef write			/* don't use redefined write() */
 
static tcptimeout_t tmoh = NIL;	/* TCP timeout handler routine */
static long ttmo_open = 0;	/* TCP timeouts, in seconds */
static long ttmo_read = 0;
static long ttmo_write = 0;
static long rshtimeout = 15;	/* rsh timeout */
static char *rshcommand = NIL;	/* rsh command */
static char *rshpath = NIL;	/* rsh path */
static long sshtimeout = 15;	/* ssh timeout */
static char *sshcommand = NIL;	/* ssh command */
static char *sshpath = NIL;	/* ssh path */
static long allowreversedns = T;/* allow reverse DNS lookup */
static long tcpdebug = NIL;	/* extra TCP debugging telemetry */

extern long maxposint;		/* get this from write.c */

/* Local function prototypes */

int tcp_socket_open (int family,void *adr,size_t adrlen,unsigned short port,
		     char *tmp,int *ctr,char *hst);
long tcp_abort (TCPSTREAM *stream);
char *tcp_name (struct sockaddr *sadr,long flag);
char *tcp_name_valid (char *s);

/* TCP/IP manipulate parameters
 * Accepts: function code
 *	    function-dependent value
 * Returns: function-dependent return value
 */

void *tcp_parameters (long function,void *value)
{
  void *ret = NIL;
  switch ((int) function) {
  case SET_TIMEOUT:
    tmoh = (tcptimeout_t) value;
  case GET_TIMEOUT:
    ret = (void *) tmoh;
    break;
  case SET_OPENTIMEOUT:
    ttmo_open = (long) value;
  case GET_OPENTIMEOUT:
    ret = (void *) ttmo_open;
    break;
  case SET_READTIMEOUT:
    ttmo_read = (long) value;
  case GET_READTIMEOUT:
    ret = (void *) ttmo_read;
    break;
  case SET_WRITETIMEOUT:
    ttmo_write = (long) value;
  case GET_WRITETIMEOUT:
    ret = (void *) ttmo_write;
    break;
  case SET_ALLOWREVERSEDNS:
    allowreversedns = (long) value;
  case GET_ALLOWREVERSEDNS:
    ret = (void *) allowreversedns;
    break;
  case SET_TCPDEBUG:
    tcpdebug = (long) value;
  case GET_TCPDEBUG:
    ret = (void *) tcpdebug;
    break;

  case SET_RSHTIMEOUT:
    rshtimeout = (long) value;
  case GET_RSHTIMEOUT:
    ret = (void *) rshtimeout;
    break;
  case SET_RSHCOMMAND:
    if (rshcommand) fs_give ((void **) &rshcommand);
    rshcommand = cpystr ((char *) value);
  case GET_RSHCOMMAND:
    ret = (void *) rshcommand;
    break;
  case SET_RSHPATH:
    if (rshpath) fs_give ((void **) &rshpath);
    rshpath = cpystr ((char *) value);
  case GET_RSHPATH:
    ret = (void *) rshpath;
    break;
  case SET_SSHTIMEOUT:
    sshtimeout = (long) value;
  case GET_SSHTIMEOUT:
    ret = (void *) sshtimeout;
    break;
  case SET_SSHCOMMAND:
    if (sshcommand) fs_give ((void **) &sshcommand);
    sshcommand = cpystr ((char *) value);
  case GET_SSHCOMMAND:
    ret = (void *) sshcommand;
    break;
  case SET_SSHPATH:
    if (sshpath) fs_give ((void **) &sshpath);
    sshpath = cpystr ((char *) value);
  case GET_SSHPATH:
    ret = (void *) sshpath;
    break;
  }
  return ret;
}

/* TCP/IP open
 * Accepts: host name
 *	    contact service name
 *	    contact port number and optional silent flag
 * Returns: TCP/IP stream if success else NIL
 */

TCPSTREAM *tcp_open (char *host,char *service,unsigned long port)
{
  TCPSTREAM *stream = NIL;
  int family;
  int sock = -1;
  int ctr = 0;
  int silent = (port & NET_SILENT) ? T : NIL;
  int *ctrp = (port & NET_NOOPENTIMEOUT) ? NIL : &ctr;
  char *s,*hostname,tmp[MAILTMPLEN];
  void *adr;
  size_t adrlen;
  struct servent *sv = NIL;
  blocknotify_t bn = (blocknotify_t) mail_parameters (NIL,GET_BLOCKNOTIFY,NIL);
  void *data,*next;
  port &= 0xffff;		/* erase flags */
				/* lookup service */
  if (service && (sv = getservbyname (service,"tcp")))
    port = ntohs (sv->s_port);
  /* The domain literal form is used (rather than simply the dotted decimal
     as with other Unix programs) because it has to be a valid "host name"
     in mailsystem terminology. */
				/* look like domain literal? */
  if (host[0] == '[' && host[(strlen (host))-1] == ']') {
    strcpy (tmp,host+1);	/* yes, copy number part */
    tmp[(strlen (tmp))-1] = '\0';
    if (adr = ip_stringtoaddr (tmp,&adrlen,&family)) {
      (*bn) (BLOCK_TCPOPEN,NIL);
				/* get an open socket for this system */
      sock = tcp_socket_open (family,adr,adrlen,port,tmp,ctrp,hostname = host);
      (*bn) (BLOCK_NONE,NIL);
      fs_give ((void **) &adr);
    }
    else sprintf (tmp,"Bad format domain-literal: %.80s",host);
  }

  else {			/* lookup host name */
    if (tcpdebug) {
      sprintf (tmp,"DNS resolution %.80s",host);
      mm_log (tmp,TCPDEBUG);
    }
    (*bn) (BLOCK_DNSLOOKUP,NIL);/* quell alarms */
    data = (*bn) (BLOCK_SENSITIVE,NIL);
    if (!(s = ip_nametoaddr (host,&adrlen,&family,&hostname,&next)))
      sprintf (tmp,"No such host as %.80s",host);
    (*bn) (BLOCK_NONSENSITIVE,data);
    (*bn) (BLOCK_NONE,NIL);
    if (s) {			/* DNS resolution won? */
      if (tcpdebug) mm_log ("DNS resolution done",TCPDEBUG);
      do {
	(*bn) (BLOCK_TCPOPEN,NIL);
	if (((sock = tcp_socket_open (family,s,adrlen,port,tmp,ctrp,
				      hostname)) < 0) &&
	    (s = ip_nametoaddr (NIL,&adrlen,&family,&hostname,&next)) &&
	    !silent) mm_log (tmp,WARN);
	(*bn) (BLOCK_NONE,NIL);
      } while ((sock < 0) && s);/* repeat until success or no more addreses */
    }
  }
  if (sock >= 0)  {		/* won */
    stream = (TCPSTREAM *) memset (fs_get (sizeof (TCPSTREAM)),0,
				   sizeof (TCPSTREAM));
    stream->port = port;	/* port number */
				/* init sockets */
    stream->tcpsi = stream->tcpso = sock;
				/* stash in the snuck-in byte */
    if (stream->ictr = ctr) *(stream->iptr = stream->ibuf) = tmp[0];
				/* copy official host name */
    stream->host = cpystr (hostname);
    if (tcpdebug) mm_log ("Stream open and ready for read",TCPDEBUG);
  }
  else if (!silent) mm_log (tmp,ERROR);
  return stream;		/* return success */
}

/* Open a TCP socket
 * Accepts: protocol family
 *	    address to connect to
 *	    address length
 *	    port
 *	    scratch buffer
 *	    pointer to "first byte read in" storage or NIL
 *	    host name for error message
 * Returns: socket if success, else -1 with error string in scratch buffer
 */

int tcp_socket_open (int family,void *adr,size_t adrlen,unsigned short port,
		     char *tmp,int *ctr,char *hst)
{
  int i,ti,sock,flgs;
  size_t len;
  time_t now;
  struct protoent *pt = getprotobyname ("tcp");
  fd_set fds,efds;
  struct timeval tmo;
  struct sockaddr *sadr = ip_sockaddr (family,adr,adrlen,port,&len);
  blocknotify_t bn = (blocknotify_t) mail_parameters (NIL,GET_BLOCKNOTIFY,NIL);
				/* fetid Solaris */
  void *data = (*bn) (BLOCK_SENSITIVE,NIL);
  sprintf (tmp,"Trying IP address [%s]",ip_sockaddrtostring (sadr));
  mm_log (tmp,NIL);
				/* make a socket */
  if ((sock = socket (sadr->sa_family,SOCK_STREAM,pt ? pt->p_proto : 0)) < 0) {
    sprintf (tmp,"Unable to create TCP socket: %s",strerror (errno));
    (*bn) (BLOCK_NONSENSITIVE,data);
  }
  else {
				/* get current socket flags */
    flgs = fcntl (sock,F_GETFL,0);
				/* set non-blocking if want open timeout */
    if (ctr) fcntl (sock,F_SETFL,flgs | FNDELAY);
				/* open connection */
    while ((i = connect (sock,sadr,len)) < 0 && (errno == EINTR));
    (*bn) (BLOCK_NONSENSITIVE,data);
    if (i < 0) switch (errno) {	/* failed? */
    case EAGAIN:		/* DG brain damage */
    case EINPROGRESS:		/* what we expect to happen */
    case EALREADY:		/* or another form of it */
    case EISCONN:		/* restart after interrupt? */
    case EADDRINUSE:		/* restart after interrupt? */
      break;			/* well, not really, it was interrupted */
    default:
      sprintf (tmp,"Can't connect to %.80s,%u: %s",hst,(unsigned int) port,
	       strerror (errno));
      close (sock);		/* flush socket */
      sock = -1;
    }

    if ((sock >= 0) && ctr) {	/* want open timeout? */
      now = time (0);		/* open timeout */
      ti = ttmo_open ? now + ttmo_open : 0;
      tmo.tv_usec = 0;
      FD_ZERO (&fds);		/* initialize selection vector */
      FD_ZERO (&efds);		/* handle errors too */
      FD_SET (sock,&fds);	/* block for error or readable */
      FD_SET (sock,&efds);
      do {			/* block under timeout */
	tmo.tv_sec = ti ? ti - now : 0;
	i = select (sock+1,&fds,NIL,&efds,ti ? &tmo : NIL);
	now = time (0);		/* fake timeout if interrupt & time expired */
	if ((i < 0) && (errno == EINTR) && ti && (ti <= now)) i = 0;
      } while ((i < 0) && (errno == EINTR));
      if (i > 0) {		/* success, make sure really connected */
				/* restore blocking status */
	fcntl (sock,F_SETFL,flgs);
	/* This used to be a zero-byte read(), but that crashes Solaris */
				/* get socket status */
	while (((i = *ctr = read (sock,tmp,1)) < 0) && (errno == EINTR));
      }	
      if (i <= 0) {		/* timeout or error? */
	i = i ? errno : ETIMEDOUT;/* determine error code */
	close (sock);		/* flush socket */
	sock = -1;
	errno = i;		/* return error code */
	sprintf (tmp,"Connection failed to %.80s,%lu: %s",hst,
		 (unsigned long) port,strerror (errno));
      }
    }
  }
  fs_give ((void **) &sadr);
  return sock;			/* return the socket */
}
  
/* TCP/IP authenticated open
 * Accepts: host name
 *	    service name
 *	    returned user name buffer
 * Returns: TCP/IP stream if success else NIL
 */

#define MAXARGV 20

TCPSTREAM *tcp_aopen (NETMBX *mb,char *service,char *usrbuf)
{
  TCPSTREAM *stream = NIL;
  void *adr;
  char host[MAILTMPLEN],tmp[MAILTMPLEN],*path,*argv[MAXARGV+1];
  int i,ti,pipei[2],pipeo[2];
  size_t len;
  time_t now;
  struct timeval tmo;
  fd_set fds,efds;
  blocknotify_t bn = (blocknotify_t) mail_parameters (NIL,GET_BLOCKNOTIFY,NIL);
  if (*service == '*') {	/* want ssh? */
				/* return immediately if ssh disabled */
    if (!(sshpath && (ti = sshtimeout))) return NIL;
				/* ssh command prototype defined yet? */
    if (!sshcommand) sshcommand = cpystr ("%s %s -l %s exec /etc/r%sd");
  }
  else if (ti = rshtimeout) {	/* set rsh timeout */
				/* rsh path/command prototypes defined yet? */
    if (!rshpath) rshpath = cpystr (RSHPATH);
    if (!rshcommand) rshcommand = cpystr ("%s %s -l %s exec /etc/r%sd");
  }
  else return NIL;		/* rsh disabled */
				/* look like domain literal? */
  if (mb->host[0] == '[' && mb->host[i = (strlen (mb->host))-1] == ']') {
    strcpy (host,mb->host+1);	/* yes, copy without brackets */
    host[i-1] = '\0';
				/* validate domain literal */
    if (adr = ip_stringtoaddr (host,&len,&i)) fs_give ((void **) &adr);
    else {
      sprintf (tmp,"Bad format domain-literal: %.80s",host);
      mm_log (tmp,ERROR);
      return NIL;
    }
  }
  else strcpy (host,tcp_canonical (mb->host));

  if (*service == '*')		/* build ssh command */
    sprintf (tmp,sshcommand,sshpath,host,
	     mb->user[0] ? mb->user : myusername (),service + 1);
  else sprintf (tmp,rshcommand,rshpath,host,
		mb->user[0] ? mb->user : myusername (),service);
  if (tcpdebug) {
    char msg[MAILTMPLEN];
    sprintf (msg,"Trying %.100s",tmp);
    mm_log (msg,TCPDEBUG);
  }
				/* parse command into argv */
  for (i = 1,path = argv[0] = strtok (tmp," ");
       (i < MAXARGV) && (argv[i] = strtok (NIL," ")); i++);
  argv[i] = NIL;		/* make sure argv tied off */
				/* make command pipes */
  if (pipe (pipei) < 0) return NIL;
  if (pipe (pipeo) < 0) {
    close (pipei[0]); close (pipei[1]);
    return NIL;
  }
  (*bn) (BLOCK_TCPOPEN,NIL);	/* quell alarm up here for NeXT */
  if ((i = fork ()) < 0) {	/* make inferior process */
    close (pipei[0]); close (pipei[1]);
    close (pipeo[0]); close (pipeo[1]);
    return NIL;
  }
  if (!i) {			/* if child */
    alarm (0);			/* never have alarms in children */
    if (!fork ()) {		/* make grandchild so it's inherited by init */
      int maxfd = max (20,max (max(pipei[0],pipei[1]),max(pipeo[0],pipeo[1])));
      dup2 (pipei[1],1);	/* parent's input is my output */
      dup2 (pipei[1],2);	/* parent's input is my error output too */
      dup2 (pipeo[0],0);	/* parent's output is my input */
				/* close all unnecessary descriptors */
      for (i = 3; i <= maxfd; i++) close (i);
      setpgrp (0,getpid ());	/* be our own process group */
      execv (path,argv);	/* now run it */
    }
    _exit (1);			/* child is done */
  }
  grim_pid_reap (i,NIL);	/* reap child; grandchild now owned by init */
  close (pipei[1]);		/* close child's side of the pipes */
  close (pipeo[0]);

				/* create TCP/IP stream */
  stream = (TCPSTREAM *) memset (fs_get (sizeof (TCPSTREAM)),0,
				 sizeof (TCPSTREAM));
				/* copy remote host name from argument */
  stream->remotehost = cpystr (stream->host = cpystr (host));
  stream->tcpsi = pipei[0];	/* init sockets */
  stream->tcpso = pipeo[1];
  stream->ictr = 0;		/* init input counter */
  stream->port = 0xffffffff;	/* no port number */
  ti += now = time (0);		/* open timeout */
  tmo.tv_usec = 0;		/* initialize usec timeout */
  FD_ZERO (&fds);		/* initialize selection vector */
  FD_ZERO (&efds);		/* handle errors too */
  FD_SET (stream->tcpsi,&fds);	/* set bit in selection vector */
  FD_SET (stream->tcpsi,&efds);	/* set bit in error selection vector */
  FD_SET (stream->tcpso,&efds);	/* set bit in error selection vector */
  do {				/* block under timeout */
    tmo.tv_sec = ti - now;
    i = select (max (stream->tcpsi,stream->tcpso)+1,&fds,NIL,&efds,&tmo);
    now = time (0);		/* fake timeout if interrupt & time expired */
    if ((i < 0) && (errno == EINTR) && ti && (ti <= now)) i = 0;
  } while ((i < 0) && (errno == EINTR));
  if (i <= 0) {			/* timeout or error? */
    sprintf (tmp,i ? "error in %s to IMAP server" :
	     "%s to IMAP server timed out",(*service == '*') ? "ssh" : "rsh");
    mm_log (tmp,WARN);
    tcp_close (stream);		/* punt stream */
    stream = NIL;
  }
  (*bn) (BLOCK_NONE,NIL);
				/* return user name */
  strcpy (usrbuf,mb->user[0] ? mb->user : myusername ());
  return stream;		/* return success */
}

/* TCP/IP receive line
 * Accepts: TCP/IP stream
 * Returns: text line string or NIL if failure
 */

char *tcp_getline (TCPSTREAM *stream)
{
  int n,m;
  char *st,*ret,*stp;
  char c = '\0';
  char d;
				/* make sure have data */
  if (!tcp_getdata (stream)) return NIL;
  st = stream->iptr;		/* save start of string */
  n = 0;			/* init string count */
  while (stream->ictr--) {	/* look for end of line */
    d = *stream->iptr++;	/* slurp another character */
    if ((c == '\015') && (d == '\012')) {
      ret = (char *) fs_get (n--);
      memcpy (ret,st,n);	/* copy into a free storage string */
      ret[n] = '\0';		/* tie off string with null */
      return ret;
    }
    n++;			/* count another character searched */
    c = d;			/* remember previous character */
  }
				/* copy partial string from buffer */
  memcpy ((ret = stp = (char *) fs_get (n)),st,n);
				/* get more data from the net */
  if (!tcp_getdata (stream)) fs_give ((void **) &ret);
				/* special case of newline broken by buffer */
  else if ((c == '\015') && (*stream->iptr == '\012')) {
    stream->iptr++;		/* eat the line feed */
    stream->ictr--;
    ret[n - 1] = '\0';		/* tie off string with null */
  }
				/* else recurse to get remainder */
  else if (st = tcp_getline (stream)) {
    ret = (char *) fs_get (n + 1 + (m = strlen (st)));
    memcpy (ret,stp,n);		/* copy first part */
    memcpy (ret + n,st,m);	/* and second part */
    fs_give ((void **) &stp);	/* flush first part */
    fs_give ((void **) &st);	/* flush second part */
    ret[n + m] = '\0';		/* tie off string with null */
  }
  return ret;
}