Initial revision

1 files changed, 1470 insertions, 0 deletions

diff --git a/lib-src/pop.c b/lib-src/pop.c
new file mode 100644
index 00000000000..9f5b5476f50
--- /dev/null
+++ b/lib-src/pop.c
@@ -0,0 +1,1470 @@
+/* pop.c: client routines for talking to a POP3-protocol post-office server
+   Copyright (c) 1991,1993 Free Software Foundation, Inc.
+   Written by Jonathan Kamens, jik@security.ov.com.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Emacs is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#ifdef MAIL_USE_POP
+
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <pop.h>
+#ifdef sun
+#include <malloc.h>
+#else
+extern char *malloc (/* unsigned */);
+extern char *realloc (/* char *, unsigned */);
+extern void free (/* char * */);
+#endif
+#endif
+#ifdef HESIOD
+#include <hesiod.h>
+/*
+ * It really shouldn't be necessary to put this declaration here, but
+ * the version of hesiod.h that Athena has installed in release 7.2
+ * doesn't declare this function; I don't know if the 7.3 version of
+ * hesiod.h does.
+ */
+extern struct servent *hes_getservbyname (/* char *, char * */);
+#endif
+#include <pwd.h>
+#include <string.h>
+#include <strings.h>
+#include <netdb.h>
+#include <errno.h>
+#include <stdio.h>
+#ifdef KERBEROS
+#ifndef KRB5
+#include <krb.h>
+#include <des.h>
+#else /* KRB5 */
+#include <krb5/krb5.h>
+#include <krb5/ext-proto.h>
+#include <ctype.h>
+#endif /* KRB5 */
+
+extern char *getenv (/* char * */);
+extern char *getlogin (/* void */);
+extern char *getpass (/* char * */);
+extern char *strerror (/* int */);
+
+#ifdef KERBEROS
+extern int krb_sendauth (/* long, int, KTEXT, char *, char *, char *,
+			 u_long, MSG_DAT *, CREDENTIALS *, Key_schedule,
+			 struct sockaddr_in *, struct sockaddr_in *,
+			 char * */);
+extern char *krb_realmofhost (/* char * */);
+#endif
+
+#ifndef HAVE_H_ERRNO
+extern int h_errno;
+#endif
+
+static int socket_connection (/* char *, int */);
+static char *getline (/* popserver */);
+static int sendline (/* popserver, char * */);
+static int fullwrite (/* int, char *, int */);
+static int getok (/* popserver */);
+#if 0
+static int gettermination (/* popserver */);
+#endif
+static void pop_trash (/* popserver */);
+
+#define ERROR_MAX 80		/* a pretty arbitrary size */
+#define POP_PORT 110
+#define KPOP_PORT 1109
+#define POP_SERVICE "pop"
+#ifdef KERBEROS
+#ifdef KRB5
+#define KPOP_SERVICE "k5pop";
+#else
+#define KPOP_SERVICE "kpop"
+#endif
+#endif
+
+char pop_error[ERROR_MAX];
+int pop_debug = 0;
+
+#ifndef min
+#define min(a,b) (((a) < (b)) ? (a) : (b))
+#endif
+
+/*
+ * Function: pop_open (char *host, char *username, char *password,
+ * 		       int flags)
+ *
+ * Purpose: Establishes a connection with a post-office server, and
+ * 	completes the authorization portion of the session.
+ *
+ * Arguments:
+ * 	host	The server host with which the connection should be
+ * 		established.  Optional.  If omitted, internal
+ * 		heuristics will be used to determine the server host,
+ * 		if possible.
+ * 	username
+ * 		The username of the mail-drop to access.  Optional.
+ * 		If omitted, internal heuristics will be used to
+ * 		determine the username, if possible.
+ * 	password
+ * 		The password to use for authorization.  If omitted,
+ * 		internal heuristics will be used to determine the
+ * 		password, if possible.
+ * 	flags	A bit mask containing flags controlling certain
+ * 		functions of the routine.  Valid flags are defined in
+ * 		the file pop.h
+ *
+ * Return value: Upon successful establishment of a connection, a
+ * 	non-null popserver will be returned.  Otherwise, null will be
+ * 	returned, and the string variable pop_error will contain an
+ * 	explanation of the error.
+ */
+popserver
+pop_open (host, username, password, flags)
+     char *host;
+     char *username;
+     char *password;
+     int flags;
+{
+  int sock;
+  popserver server;
+
+  /* Determine the user name */
+  if (! username)
+    {
+      username = getenv ("USER");
+      if (! (username && *username))
+	{
+	  username = getlogin ();
+	  if (! (username && *username))
+	    {
+	      struct passwd *passwd;
+	      passwd = getpwuid (getuid ());
+	      if (passwd && passwd->pw_name && *passwd->pw_name)
+		{
+		  username = passwd->pw_name;
+		}
+	      else
+		{
+		  strcpy (pop_error, "Could not determine username");
+		  return (0);
+		}
+	    }
+	}
+    }
+
+  /*
+   *  Determine the mail host.
+   */
+
+  if (! host)
+    {
+      host = getenv ("MAILHOST");
+    }
+
+#ifdef HESIOD
+  if ((! host) && (! (flags & POP_NO_HESIOD)))
+    {
+      struct hes_postoffice *office;
+      office = hes_getmailhost (username);
+      if (office && office->po_type && (! strcmp (office->po_type, "POP"))
+	  && office->po_name && *office->po_name && office->po_host
+	  && *office->po_host)
+	{
+	  host = office->po_host;
+	  username = office->po_name;
+	}
+    }
+#endif
+
+#ifdef MAILHOST
+  if (! host)
+    {
+      host = MAILHOST;
+    }
+#endif
+
+  if (! host)
+    {
+      strcpy (pop_error, "Could not determine POP server");
+      return (0);
+    }
+
+  /* Determine the password */
+#ifdef KERBEROS
+#define DONT_NEED_PASSWORD (! (flags & POP_NO_KERBEROS))
+#else
+#define DONT_NEED_PASSWORD 0
+#endif
+ 
+  if ((! password) && (! DONT_NEED_PASSWORD))
+    {
+      if (! (flags & POP_NO_GETPASS))
+	{
+	  password = getpass ("Enter POP password:");
+	}
+      if (! password)
+	{
+	  strcpy (pop_error, "Could not determine POP password");
+	  return (0);
+	}
+    }
+  if (password)
+    flags |= POP_NO_KERBEROS;
+  else
+    password = username;
+
+  sock = socket_connection (host, flags);
+  if (sock == -1)
+    return (0);
+
+  server = (popserver) malloc (sizeof (struct _popserver));
+  if (! server)
+    {
+      strcpy (pop_error, "Out of memory in pop_open");
+      return (0);
+    }
+  server->buffer = (char *) malloc (GETLINE_MIN);
+  if (! server->buffer)
+    {
+      strcpy (pop_error, "Out of memory in pop_open");
+      free ((char *) server);
+      return (0);
+    }
+	  
+  server->file = sock;
+  server->data = 0;
+  server->buffer_index = 0;
+  server->buffer_size = GETLINE_MIN;
+  server->in_multi = 0;
+
+  if (getok (server))
+    return (0);
+
+  /*
+   * I really shouldn't use the pop_error variable like this, but....
+   */
+  if (strlen (username) > ERROR_MAX - 6)
+    {
+      pop_close (server);
+      strcpy (pop_error,
+	      "Username too long; recompile pop.c with larger ERROR_MAX");
+      return (0);
+    }
+  sprintf (pop_error, "USER %s", username);
+
+  if (sendline (server, pop_error) || getok (server))
+    {
+      return (0);
+    }
+
+  if (strlen (password) > ERROR_MAX - 6)
+    {
+      pop_close (server);
+      strcpy (pop_error,
+	      "Password too long; recompile pop.c with larger ERROR_MAX");
+      return (0);
+    }
+  sprintf (pop_error, "PASS %s", password);
+
+  if (sendline (server, pop_error) || getok (server))
+    {
+      return (0);
+    }
+
+  return (server);
+}
+
+/*
+ * Function: pop_stat
+ *
+ * Purpose: Issue the STAT command to the server and return (in the
+ * 	value parameters) the number of messages in the maildrop and
+ * 	the total size of the maildrop.
+ *
+ * Return value: 0 on success, or non-zero with an error in pop_error
+ * 	in failure.
+ *
+ * Side effects: On failure, may make further operations on the
+ * 	connection impossible.
+ */
+int
+pop_stat (server, count, size)
+     popserver server;
+     int *count;
+     int *size;
+{
+  char *fromserver;
+
+  if (server->in_multi)
+    {
+      strcpy (pop_error, "In multi-line query in pop_stat");
+      return (-1);
+    }
+     
+  if (sendline (server, "STAT") || (! (fromserver = getline (server))))
+    return (-1);
+
+  if (strncmp (fromserver, "+OK ", 4))
+    {
+      if (0 == strncmp (fromserver, "-ERR", 4))
+	{
+	  strncpy (pop_error, fromserver, ERROR_MAX);
+	}
+      else
+	{
+	  strcpy (pop_error,
+		  "Unexpected response from POP server in pop_stat");
+	  pop_trash (server);
+	}
+      return (-1);
+    }
+
+  *count = atoi (&fromserver[4]);
+     
+  fromserver = index (&fromserver[4], ' ');
+  if (! fromserver)
+    {
+      strcpy (pop_error,
+	      "Badly formatted response from server in pop_stat");
+      pop_trash (server);
+      return (-1);
+    }
+
+  *size = atoi (fromserver + 1);
+
+  return (0);
+}
+
+/*
+ * Function: pop_list
+ *
+ * Purpose: Performs the POP "list" command and returns (in value
+ * 	parameters) two malloc'd zero-terminated arrays -- one of
+ * 	message IDs, and a parallel one of sizes.
+ *
+ * Arguments:
+ * 	server	The pop connection to talk to.
+ * 	message	The number of the one message about which to get
+ * 		information, or 0 to get information about all
+ * 		messages.
+ *
+ * Return value: 0 on success, non-zero with error in pop_error on
+ * 	failure.
+ *
+ * Side effects: On failure, may make further operations on the
+ * 	connection impossible.
+ */
+int
+pop_list (server, message, IDs, sizes)
+     popserver server;
+     int message;
+     int **IDs;
+     int **sizes;
+{
+  int how_many, i;
+  char *fromserver;
+
+  if (server->in_multi)
+    {
+      strcpy (pop_error, "In multi-line query in pop_list");
+      return (-1);
+    }
+
+  if (message)
+    how_many = 1;
+  else
+    {
+      int count, size;
+      if (pop_stat (server, &count, &size))
+	return (-1);
+      how_many = count;
+    }
+
+  *IDs = (int *) malloc ((how_many + 1) * sizeof (int));
+  *sizes = (int *) malloc ((how_many + 1) * sizeof (int));
+  if (! (*IDs && *sizes))
+    {
+      strcpy (pop_error, "Out of memory in pop_list");
+      return (-1);
+    }
+
+  if (message)
+    {
+      sprintf (pop_error, "LIST %d", message);
+      if (sendline (server, pop_error))
+	{
+	  free ((char *) *IDs);
+	  free ((char *) *sizes);
+	  return (-1);
+	}
+      if (! (fromserver = getline (server)))
+	{
+	  free ((char *) *IDs);
+	  free ((char *) *sizes);
+	  return (-1);
+	}
+      if (strncmp (fromserver, "+OK ", 4))
+	{
+	  if (! strncmp (fromserver, "-ERR", 4))
+	    strncpy (pop_error, fromserver, ERROR_MAX);
+	  else
+	    {
+	      strcpy (pop_error,
+		      "Unexpected response from server in pop_list");
+	      pop_trash (server);
+	    }
+	  free ((char *) *IDs);
+	  free ((char *) *sizes);
+	  return (-1);
+	}
+      (*IDs)[0] = atoi (&fromserver[4]);
+      fromserver = index (&fromserver[4], ' ');
+      if (! fromserver)
+	{
+	  strcpy (pop_error,
+		  "Badly formatted response from server in pop_list");
+	  pop_trash (server);
+	  free ((char *) *IDs);
+	  free ((char *) *sizes);
+	  return (-1);
+	}
+      (*sizes)[0] = atoi (fromserver);
+      (*IDs)[1] = (*sizes)[1] = 0;
+      return (0);
+    }
+  else
+    {
+      if (pop_multi_first (server, "LIST", &fromserver))
+	{
+	  free ((char *) *IDs);
+	  free ((char *) *sizes);
+	  return (-1);
+	}
+      for (i = 0; i < how_many; i++)
+	{
+	  if (pop_multi_next (server, &fromserver))
+	    {
+	      free ((char *) *IDs);
+	      free ((char *) *sizes);
+	      return (-1);
+	    }
+	  (*IDs)[i] = atoi (fromserver);
+	  fromserver = index (fromserver, ' ');
+	  if (! fromserver)
+	    {
+	      strcpy (pop_error,
+		      "Badly formatted response from server in pop_list");
+	      free ((char *) *IDs);
+	      free ((char *) *sizes);
+	      pop_trash (server);
+	      return (-1);
+	    }
+	  (*sizes)[i] = atoi (fromserver);
+	}
+      if (pop_multi_next (server, &fromserver))
+	{
+	  free ((char *) *IDs);
+	  free ((char *) *sizes);
+	  return (-1);
+	}
+      else if (fromserver)
+	{
+	  strcpy (pop_error,
+		  "Too many response lines from server in pop_list");
+	  free ((char *) *IDs);
+	  free ((char *) *sizes);
+	  return (-1);
+	}
+      (*IDs)[i] = (*sizes)[i] = 0;
+      return (0);
+    }
+}
+
+/*
+ * Function: pop_retrieve
+ *
+ * Purpose: Retrieve a specified message from the maildrop.
+ *
+ * Arguments:
+ * 	server	The server to retrieve from.
+ * 	message	The message number to retrieve.
+ *	markfrom
+ * 		If true, then mark the string "From " at the beginning
+ * 		of lines with '>'.
+ * 
+ * Return value: A string pointing to the message, if successful, or
+ * 	null with pop_error set if not.
+ *
+ * Side effects: May kill connection on error.
+ */
+char *
+pop_retrieve (server, message, markfrom)
+     popserver server;
+     int message;
+     int markfrom;
+{
+  int *IDs, *sizes, bufsize, fromcount = 0, cp = 0;
+  char *ptr, *fromserver;
+  int ret;
+
+  if (server->in_multi)
+    {
+      strcpy (pop_error, "In multi-line query in pop_retrieve");
+      return (0);
+    }
+
+  if (pop_list (server, message, &IDs, &sizes))
+    return (0);
+
+  if (pop_retrieve_first (server, message, &fromserver))
+    {
+      return (0);
+    }
+
+  /*
+   * The "5" below is an arbitrary constant -- I assume that if
+   * there are "From" lines in the text to be marked, there
+   * probably won't be more than 5 of them.  If there are, I
+   * allocate more space for them below.
+   */
+  bufsize = sizes[0] + (markfrom ? 5 : 0);
+  ptr = malloc (bufsize);
+  free ((char *) IDs);
+  free ((char *) sizes);
+
+  if (! ptr)
+    {
+      strcpy (pop_error, "Out of memory in pop_retrieve");
+      pop_retrieve_flush (server);
+      return (0);
+    }
+
+  while (! (ret = pop_retrieve_next (server, &fromserver)))
+    {
+      int linesize;
+
+      if (! fromserver)
+	{
+	  ptr[cp] = '\0';
+	  return (ptr);
+	}
+      if (markfrom && fromserver[0] == 'F' && fromserver[1] == 'r' &&
+	  fromserver[2] == 'o' && fromserver[3] == 'm' &&
+	  fromserver[4] == ' ')
+	{
+	  if (++fromcount == 5)
+	    {
+	      bufsize += 5;
+	      ptr = realloc (ptr, bufsize);
+	      if (! ptr)
+		{
+		  strcpy (pop_error, "Out of memory in pop_retrieve");
+		  pop_retrieve_flush (server);
+		  return (0);
+		}
+	      fromcount = 0;
+	    }
+	  ptr[cp++] = '>';
+	}
+      linesize = strlen (fromserver);
+      bcopy (fromserver, &ptr[cp], linesize);
+      cp += linesize;
+      ptr[cp++] = '\n';
+    }
+
+  if (ret)
+    {
+      free (ptr);
+      return (0);
+    }
+}     
+
+int
+pop_retrieve_first (server, message, response)
+     popserver server;
+     int message;
+     char **response;
+{
+  sprintf (pop_error, "RETR %d", message);
+  return (pop_multi_first (server, pop_error, response));
+}
+
+int
+pop_retrieve_next (server, line)
+     popserver server;
+     char **line;
+{
+  return (pop_multi_next (server, line));
+}
+
+int
+pop_retrieve_flush (server)
+     popserver server;
+{
+  return (pop_multi_flush (server));
+}
+
+int
+pop_top_first (server, message, lines, response)
+     popserver server;
+     int message, lines;
+     char **response;
+{
+  sprintf (pop_error, "TOP %d %d", message, lines);
+  return (pop_multi_first (server, pop_error, response));
+}
+
+int
+pop_top_next (server, line)
+     popserver server;
+     char **line;
+{
+  return (pop_multi_next (server, line));
+}
+
+int
+pop_top_flush (server)
+     popserver server;
+{
+  return (pop_multi_flush (server));
+}
+
+int
+pop_multi_first (server, command, response)
+     popserver server;
+     char *command;
+     char **response;
+{
+  if (server->in_multi)
+    {
+      strcpy (pop_error,
+	      "Already in multi-line query in pop_multi_first");
+      return (-1);
+    }
+
+  if (sendline (server, command) || (! (*response = getline (server))))
+    {
+      return (-1);
+    }
+
+  if (0 == strncmp (*response, "-ERR", 4))
+    {
+      strncpy (pop_error, *response, ERROR_MAX);
+      return (-1);
+    }
+  else if (0 == strncmp (*response, "+OK", 3))
+    {
+      for (*response += 3; **response == ' '; (*response)++) /* empty */;
+      server->in_multi = 1;
+      return (0);
+    }
+  else
+    {
+      strcpy (pop_error,
+	      "Unexpected response from server in pop_multi_first");
+      return (-1);
+    }
+}
+
+int
+pop_multi_next (server, line)
+     popserver server;
+     char **line;
+{
+  char *fromserver;
+
+  if (! server->in_multi)
+    {
+      strcpy (pop_error, "Not in multi-line query in pop_multi_next");
+      return (-1);
+    }
+
+  fromserver = getline (server);
+  if (! fromserver)
+    {
+      return (-1);
+    }
+
+  if (fromserver[0] == '.')
+    {
+      if (! fromserver[1])
+	{
+	  *line = 0;
+	  server->in_multi = 0;
+	  return (0);
+	}
+      else
+	{
+	  *line = fromserver + 1;
+	  return (0);
+	}
+    }
+  else
+    {
+      *line = fromserver;
+      return (0);
+    }
+}
+
+int
+pop_multi_flush (server)
+     popserver server;
+{
+  char *line;
+
+  if (! server->in_multi)
+    {
+      return (0);
+    }
+
+  while (! pop_multi_next (server, &line))
+    {
+      if (! line)
+	{
+	  return (0);
+	}
+    }
+
+  return (-1);
+}
+
+/* Function: pop_delete
+ *
+ * Purpose: Delete a specified message.
+ *
+ * Arguments:
+ * 	server	Server from which to delete the message.
+ * 	message	Message to delete.
+ *
+ * Return value: 0 on success, non-zero with error in pop_error
+ * 	otherwise.
+ */
+int
+pop_delete (server, message)
+     popserver server;
+     int message;
+{
+  if (server->in_multi)
+    {
+      strcpy (pop_error, "In multi-line query in pop_delete");
+      return (-1);
+    }
+
+  sprintf (pop_error, "DELE %d", message);
+
+  if (sendline (server, pop_error) || getok (server))
+    return (-1);
+
+  return (0);
+}
+
+/*
+ * Function: pop_noop
+ *
+ * Purpose: Send a noop command to the server.
+ *
+ * Argument:
+ * 	server	The server to send to.
+ *
+ * Return value: 0 on success, non-zero with error in pop_error
+ * 	otherwise.
+ *
+ * Side effects: Closes connection on error.
+ */
+int
+pop_noop (server)
+     popserver server;
+{
+  if (server->in_multi)
+    {
+      strcpy (pop_error, "In multi-line query in pop_noop");
+      return (-1);
+    }
+
+  if (sendline (server, "NOOP") || getok (server))
+    return (-1);
+
+  return (0);
+}
+
+/*
+ * Function: pop_last
+ *
+ * Purpose: Find out the highest seen message from the server.
+ *
+ * Arguments:
+ * 	server	The server.
+ *
+ * Return value: If successful, the highest seen message, which is
+ * 	greater than or equal to 0.  Otherwise, a negative number with
+ * 	the error explained in pop_error.
+ *
+ * Side effects: Closes the connection on error.
+ */
+int
+pop_last (server)
+     popserver server;
+{
+  char *fromserver;
+     
+  if (server->in_multi)
+    {
+      strcpy (pop_error, "In multi-line query in pop_last");
+      return (-1);
+    }
+
+  if (sendline (server, "LAST"))
+    return (-1);
+
+  if (! (fromserver = getline (server)))
+    return (-1);
+
+  if (! strncmp (fromserver, "-ERR", 4))
+    {
+      strncpy (pop_error, fromserver, ERROR_MAX);
+      return (-1);
+    }
+  else if (strncmp (fromserver, "+OK ", 4))
+    {
+      strcpy (pop_error, "Unexpected response from server in pop_last");
+      pop_trash (server);
+      return (-1);
+    }
+  else
+    {
+      return (atoi (&fromserver[4]));
+    }
+}
+
+/*
+ * Function: pop_reset
+ *
+ * Purpose: Reset the server to its initial connect state
+ *
+ * Arguments:
+ * 	server	The server.
+ *
+ * Return value: 0 for success, non-0 with error in pop_error
+ * 	otherwise.
+ *
+ * Side effects: Closes the connection on error.
+ */
+int
+pop_reset (server)
+     popserver server;
+{
+  if (pop_retrieve_flush (server))
+    {
+      return (-1);
+    }
+
+  if (sendline (server, "RSET") || getok (server))
+    return (-1);
+
+  return (0);
+}
+
+/*
+ * Function: pop_quit
+ *
+ * Purpose: Quit the connection to the server,
+ *
+ * Arguments:
+ * 	server	The server to quit.
+ *
+ * Return value: 0 for success, non-zero otherwise with error in
+ * 	pop_error.
+ *
+ * Side Effects: The popserver passed in is unuseable after this
+ * 	function is called, even if an error occurs.
+ */
+int
+pop_quit (server)
+     popserver server;
+{
+  int ret = 0;
+
+  if (server->file >= 0)
+    {
+      if (pop_retrieve_flush (server))
+	{
+	  ret = -1;
+	}
+
+      if (sendline (server, "QUIT") || getok (server))
+	{
+	  ret = -1;
+	}
+
+      close (server->file);
+    }
+
+  if (server->buffer)
+    free (server->buffer);
+  free ((char *) server);
+
+  return (ret);
+}
+
+/*
+ * Function: socket_connection
+ *
+ * Purpose: Opens the network connection with the mail host, without
+ * 	doing any sort of I/O with it or anything.
+ *
+ * Arguments:
+ * 	host	The host to which to connect.
+ *	flags	Option flags.
+ * 	
+ * Return value: A file descriptor indicating the connection, or -1
+ * 	indicating failure, in which case an error has been copied
+ * 	into pop_error.
+ */
+static int
+socket_connection (host, flags)
+     char *host;
+     int flags;
+{
+  struct hostent *hostent;
+  struct servent *servent;
+  struct sockaddr_in addr;
+  char found_port = 0;
+  char *service;
+  int sock;
+#ifdef KERBEROS
+#ifdef KRB5
+  krb5_error_code rem;
+  krb5_ccache ccdef;
+  krb5_principal client, server;
+  krb5_error *err_ret;
+  register char *cp;
+#else
+  KTEXT ticket;
+  MSG_DAT msg_data;
+  CREDENTIALS cred;
+  Key_schedule schedule;
+  int rem;
+#endif /* KRB5 */
+#endif /* KERBEROS */
+
+  int try_count = 0;
+
+  do
+    {
+      hostent = gethostbyname (host);
+      try_count++;
+      if ((! hostent) && ((h_errno != TRY_AGAIN) || (try_count == 5)))
+	{
+	  strcpy (pop_error, "Could not determine POP server's address");
+	  return (-1);
+	}
+    } while (! hostent);
+
+  bzero ((char *) &addr, sizeof (addr));
+  addr.sin_family = AF_INET;
+
+#ifdef KERBEROS
+  service = (flags & POP_NO_KERBEROS) ? POP_SERVICE : KPOP_SERVICE;
+#else
+  service = POP_SERVICE;
+#endif
+
+#ifdef HESIOD
+  if (! (flags & POP_NO_HESIOD))
+    {
+      servent = hes_getservbyname (service, "tcp");
+      if (servent)
+	{
+	  addr.sin_port = servent->s_port;
+	  found_port = 1;
+	}
+    }
+#endif
+  if (! found_port)
+    {
+      servent = getservbyname (service, "tcp");
+      if (servent)
+	{
+	  addr.sin_port = servent->s_port;
+	}
+      else
+	{
+#ifdef KERBEROS
+	  addr.sin_port = htons ((flags & POP_NO_KERBEROS) ?
+				POP_PORT : KPOP_PORT);
+#else
+	  addr.sin_port = htons (POP_PORT);
+#endif
+	}
+    }
+
+#define SOCKET_ERROR "Could not create socket for POP connection: "
+
+  sock = socket (PF_INET, SOCK_STREAM, 0);
+  if (sock < 0)
+    {
+      strcpy (pop_error, SOCKET_ERROR);
+      strncat (pop_error, strerror (errno),
+	       ERROR_MAX - sizeof (SOCKET_ERROR));
+      return (-1);
+	  
+    }
+
+  while (*hostent->h_addr_list)
+    {
+      bcopy (*hostent->h_addr_list, (char *) &addr.sin_addr,
+	     hostent->h_length);
+      if (! connect (sock, (struct sockaddr *) &addr, sizeof (addr)))
+	break;
+      hostent->h_addr_list++;
+    }
+
+#define CONNECT_ERROR "Could not connect to POP server: "
+     
+  if (! *hostent->h_addr_list)
+    {
+      (void) close (sock);
+      strcpy (pop_error, CONNECT_ERROR);
+      strncat (pop_error, strerror (errno),
+	       ERROR_MAX - sizeof (CONNECT_ERROR));
+      return (-1);
+	  
+    }
+
+#ifdef KERBEROS
+#define KRB_ERROR "Kerberos error connecting to POP server: "
+  if (! (flags & POP_NO_KERBEROS))
+    {
+#ifdef KRB5
+      krb5_init_ets ();
+
+      if (rem = krb5_cc_default (&ccdef))
+	{
+	krb5error:
+	  strcpy (pop_error, KRB_ERROR);
+	  strncat (pop_error, error_message (rem),
+		   ERROR_MAX - sizeof(KRB_ERROR));
+	  (void) close (sock);
+	  return (-1);
+	}
+
+      if (rem = krb5_cc_get_principal (ccdef, &client))
+	{
+	  goto krb5error;
+	}
+
+      for (cp = hostent->h_name; *cp; cp++)
+	{
+	  if (isupper (*cp))
+	    {
+	      *cp = tolower (*cp);
+	    }
+	}
+
+      if (rem = krb5_sname_to_principal (hostent->h_name, POP_SERVICE,
+					 FALSE, &server))
+	{
+	  goto krb5error;
+	}
+
+      rem = krb5_sendauth ((krb5_pointer) &sock, "KPOPV1.0", client, server,
+			  AP_OPTS_MUTUAL_REQUIRED,
+			  0,	/* no checksum */
+			  0,	/* no creds, use ccache instead */
+			  ccdef,
+			  0,	/* don't need seq # */
+			  0,	/* don't need subsession key */
+			  &err_ret,
+			  0);	/* don't need reply */
+      krb5_free_principal (server);
+      if (rem)
+	{
+	  if (err_ret && err_ret->text.length)
+	    {
+	      strcpy (pop_error, KRB_ERROR);
+	      strncat (pop_error, error_message (rem),
+		       ERROR_MAX - sizeof (KRB_ERROR));
+	      strncat (pop_error, " [server says '",
+		       ERROR_MAX - strlen (pop_error) - 1);
+	      strncat (pop_error, err_ret->text.data,
+		       min (ERROR_MAX - strlen (pop_error) - 1,
+			    err_ret->text.length));
+	      strncat (pop_error, "']",
+		       ERROR_MAX - strlen (pop_error) - 1);
+	    }
+	  else
+	    {
+	      strcpy (pop_error, KRB_ERROR);
+	      strncat (pop_error, error_message (rem),
+		       ERROR_MAX - sizeof (KRB_ERROR));
+	    }
+	  if (err_ret)
+	    krb5_free_error (err_ret);
+
+	  (void) close (sock);
+	  return (-1);
+	}
+#else  /* ! KRB5 */	  
+      ticket = (KTEXT) malloc (sizeof (KTEXT_ST));
+      rem = krb_sendauth (0L, sock, ticket, "pop", hostent->h_name,
+			  (char *) krb_realmofhost (hostent->h_name),
+			  (unsigned long) 0, &msg_data, &cred, schedule,
+			  (struct sockaddr_in *) 0,
+			  (struct sockaddr_in *) 0,
+			  "KPOPV0.1");
+      free ((char *) ticket);
+      if (rem != KSUCCESS)
+	{
+	  strcpy (pop_error, KRB_ERROR);
+	  strncat (pop_error, krb_err_txt[rem],
+		   ERROR_MAX - sizeof (KRB_ERROR));
+	  (void) close (sock);
+	  return (-1);
+	}
+#endif /* KRB5 */
+    }
+#endif /* KERBEROS */
+
+  return (sock);
+} /* socket_connection */
+
+/*
+ * Function: getline
+ *
+ * Purpose: Get a line of text from the connection and return a
+ * 	pointer to it.  The carriage return and linefeed at the end of
+ * 	the line are stripped, but periods at the beginnings of lines
+ * 	are NOT dealt with in any special way.
+ *
+ * Arguments:
+ * 	server	The server from which to get the line of text.
+ *
+ * Returns: A non-null pointer if successful, or a null pointer on any
+ * 	error, with an error message copied into pop_error.
+ *
+ * Notes: The line returned is overwritten with each call to getline.
+ *
+ * Side effects: Closes the connection on error.
+ */
+static char *
+getline (server)
+     popserver server;
+{
+#define GETLINE_ERROR "Error reading from server: "
+
+  int ret;
+     
+  if (server->data)
+    {
+      char *cp = strstr (server->buffer + server->buffer_index, "\r\n");
+      if (cp)
+	{
+	  int found;
+	  int data_used;
+
+	  found = server->buffer_index;
+	  data_used = (cp + 2) - server->buffer - found;
+	       
+	  *cp = '\0';		/* terminate the string to be returned */
+	  server->data -= data_used;
+	  server->buffer_index += data_used;
+
+	  if (pop_debug)
+	    fprintf (stderr, "<<< %s\n", server->buffer + found);
+	  return (server->buffer + found);
+	}
+      else
+	{
+	  bcopy (server->buffer + server->buffer_index,
+		 server->buffer, server->data);
+	  server->buffer_index = 0;
+	}
+    }
+  else
+    {
+      server->buffer_index = 0;
+    }
+
+  while (1)
+    {
+      if (server->data == server->buffer_size)
+	{
+	  server->buffer_size += GETLINE_INCR;
+	  server->buffer = realloc (server->buffer, server->buffer_size);
+	  if (! server->buffer)
+	    {
+	      strcpy (pop_error, "Out of memory in getline");
+	      pop_trash (server);
+	      return (0);
+	    }
+	}
+      ret = read (server->file, server->buffer + server->data,
+		  server->buffer_size - server->data);
+      if (ret < 0)
+	{
+	  strcpy (pop_error, GETLINE_ERROR);
+	  strncat (pop_error, strerror (errno),
+		   ERROR_MAX - sizeof (GETLINE_ERROR));
+	  pop_trash (server);
+	  return (0);
+	}
+      else if (ret == 0)
+	{
+	  strcpy (pop_error, "Unexpected EOF from server in getline");
+	  pop_trash (server);
+	  return (0);
+	}
+      else
+	{
+	  char *cp = strstr (server->buffer, "\r\n");
+	  server->data += ret;
+	       
+	  if (cp)
+	    {
+	      int data_used = (cp + 2) - server->buffer;
+	      *cp = '\0';
+	      server->data -= data_used;
+	      server->buffer_index = data_used;
+
+	      if (pop_debug)
+		fprintf (stderr, "<<< %s\n", server->buffer);
+	      return (server->buffer);
+	    }
+	}
+    }
+
+  /* NOTREACHED */
+}
+
+/*
+ * Function: sendline
+ *
+ * Purpose: Sends a line of text to the POP server.  The line of text
+ * 	passed into this function should NOT have the carriage return
+ * 	and linefeed on the end of it.  Periods at beginnings of lines
+ * 	will NOT be treated specially by this function.
+ *
+ * Arguments:
+ * 	server	The server to which to send the text.
+ * 	line	The line of text to send.
+ *
+ * Return value: Upon successful completion, a value of 0 will be
+ * 	returned.  Otherwise, a non-zero value will be returned, and
+ * 	an error will be copied into pop_error.
+ *
+ * Side effects: Closes the connection on error.
+ */
+static int
+sendline (server, line)
+     popserver server;
+     char *line;
+{
+#define SENDLINE_ERROR "Error writing to POP server: "
+  int ret;
+
+  ret = fullwrite (server->file, line, strlen (line));
+  if (ret >= 0)
+    {				/* 0 indicates that a blank line was written */
+      ret = fullwrite (server->file, "\r\n", 2);
+    }
+
+  if (ret < 0)
+    {
+      pop_trash (server);
+      strcpy (pop_error, SENDLINE_ERROR);
+      strncat (pop_error, strerror (errno),
+	       ERROR_MAX - sizeof (SENDLINE_ERROR));
+      return (ret);
+    }
+
+  if (pop_debug)
+    fprintf (stderr, ">>> %s\n", line);
+
+  return (0);
+}
+
+/*
+ * Procedure: fullwrite
+ *
+ * Purpose: Just like write, but keeps trying until the entire string
+ * 	has been written.
+ *
+ * Return value: Same as write.  Pop_error is not set.
+ */
+static int
+fullwrite (fd, buf, nbytes)
+     int fd;
+     char *buf;
+     int nbytes;
+{
+  char *cp;
+  int ret;
+
+  cp = buf;
+  while ((ret = write (fd, cp, nbytes)) > 0)
+    {
+      cp += ret;
+      nbytes -= ret;
+    }
+
+  return (ret);
+}
+
+/*
+ * Procedure getok
+ *
+ * Purpose: Reads a line from the server.  If the return indicator is
+ * 	positive, return with a zero exit status.  If not, return with
+ * 	a negative exit status.
+ *
+ * Arguments:
+ * 	server	The server to read from.
+ * 
+ * Returns: 0 for success, else for failure and puts error in pop_error.
+ *
+ * Side effects: On failure, may make the connection unuseable.
+ */
+static int
+getok (server)
+     popserver server;
+{
+  char *fromline;
+
+  if (! (fromline = getline (server)))
+    {
+      return (-1);
+    }
+
+  if (! strncmp (fromline, "+OK", 3))
+    return (0);
+  else if (! strncmp (fromline, "-ERR", 4))
+    {
+      strncpy (pop_error, fromline, ERROR_MAX);
+      pop_error[ERROR_MAX-1] = '\0';
+      return (-1);
+    }
+  else
+    {
+      strcpy (pop_error,
+	      "Unexpected response from server; expecting +OK or -ERR");
+      pop_trash (server);
+      return (-1);
+    }
+}	  
+
+#if 0
+/*
+ * Function: gettermination
+ *
+ * Purpose: Gets the next line and verifies that it is a termination
+ * 	line (nothing but a dot).
+ *
+ * Return value: 0 on success, non-zero with pop_error set on error.
+ *
+ * Side effects: Closes the connection on error.
+ */
+static int
+gettermination (server)
+     popserver server;
+{
+  char *fromserver;
+
+  fromserver = getline (server);
+  if (! fromserver)
+    return (-1);
+
+  if (strcmp (fromserver, "."))
+    {
+      strcpy (pop_error,
+	      "Unexpected response from server in gettermination");
+      pop_trash (server);
+      return (-1);
+    }
+
+  return (0);
+}
+#endif
+
+/*
+ * Function pop_close
+ *
+ * Purpose: Close a pop connection, sending a "RSET" command to try to
+ * 	preserve any changes that were made and a "QUIT" command to
+ * 	try to get the server to quit, but ignoring any responses that
+ * 	are received.
+ *
+ * Side effects: The server is unuseable after this function returns.
+ * 	Changes made to the maildrop since the session was started (or
+ * 	since the last pop_reset) may be lost.
+ */
+void 
+pop_close (server)
+     popserver server;
+{
+  pop_trash (server);
+  free ((char *) server);
+
+  return;
+}
+
+/*
+ * Function: pop_trash
+ *
+ * Purpose: Like pop_close or pop_quit, but doesn't deallocate the
+ * 	memory associated with the server.  It is legal to call
+ * 	pop_close or pop_quit after this function has been called.
+ */
+static void
+pop_trash (server)
+     popserver server;
+{
+  if (server->file >= 0)
+    {
+      sendline (server, "RSET");
+      sendline (server, "QUIT");
+
+      close (server->file);
+      server->file = -1;
+      if (server->buffer)
+	{
+	  free (server->buffer);
+	  server->buffer = 0;
+	}
+    }
+}
+
+/* Search in STRING for an occurrence of SUBSTRING
+   and return a pointer to that occurrence.
+   Return 0 if SUBSTRING does not occur in STRING.  */
+
+static char *
+my_strstr (string, substring)
+     char *string, *substring;
+{
+  char *p = string;
+
+  while (*p)
+    {
+      if (!strcmp (p, substring))
+	return p;
+      p++;
+    }
+  return 0;
+}
+
+#endif /* MAIL_USE_POP */