command.c

mutt-1.5.12 源代码。linux 下邮件接受的工具。

/*
 * Copyright (C) 1996-8 Michael R. Elkins <[e-mail]>
 * Copyright (C) 1996-9 Brandon Long <[e-mail]>
 * Copyright (C) 1999-2006 Brendan Cully <[e-mail]>
 * 
 *     This program 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 of the License, or
 *     (at your option) any later version.
 * 
 *     This program 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 this program; if not, write to the Free Software
 *     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */ 

/* command.c: routines for sending commands to an IMAP server and parsing
 *  responses */

#if HAVE_CONFIG_H
# include "config.h"
#endif

#include "mutt.h"
#include "imap_private.h"
#include "message.h"
#include "mx.h"
#include "buffy.h"

#include <ctype.h>
#include <stdlib.h>

#define IMAP_CMD_BUFSIZE 512

/* forward declarations */
static IMAP_COMMAND* cmd_new (IMAP_DATA* idata);
static int cmd_status (const char *s);
static void cmd_handle_fatal (IMAP_DATA* idata);
static int cmd_handle_untagged (IMAP_DATA* idata);
static void cmd_parse_capability (IMAP_DATA* idata, char* s);
static void cmd_parse_expunge (IMAP_DATA* idata, const char* s);
static void cmd_parse_list (IMAP_DATA* idata, char* s);
static void cmd_parse_lsub (IMAP_DATA* idata, char* s);
static void cmd_parse_fetch (IMAP_DATA* idata, char* s);
static void cmd_parse_myrights (IMAP_DATA* idata, const char* s);
static void cmd_parse_search (IMAP_DATA* idata, const char* s);
static void cmd_parse_status (IMAP_DATA* idata, char* s);

static char *Capabilities[] = {
  "IMAP4",
  "IMAP4rev1",
  "STATUS",
  "ACL", 
  "NAMESPACE",
  "AUTH=CRAM-MD5",
  "AUTH=GSSAPI",
  "AUTH=ANONYMOUS",
  "STARTTLS",
  "LOGINDISABLED",
  "IDLE",
  "SASL-IR",

  NULL
};

/* imap_cmd_queue: Add command to command queue. Fails if the queue is full. */
int imap_cmd_queue (IMAP_DATA* idata, const char* cmdstr)
{
  IMAP_COMMAND* cmd;

  if (idata->status == IMAP_FATAL)
  {
    cmd_handle_fatal (idata);
    return IMAP_CMD_BAD;
  }

  if (!(cmd = cmd_new (idata)))
    return IMAP_CMD_BAD;

  if (mutt_buffer_printf (idata->cmdbuf, "%s%s %s\r\n",
      idata->state == IMAP_IDLE ? "DONE\r\n" : "", cmd->seq, cmdstr) < 0)
    return IMAP_CMD_BAD;

  if (idata->state == IMAP_IDLE)
    idata->state = IMAP_SELECTED;

  return 0;
}

/* imap_cmd_start: Given an IMAP command, send it to the server.
 *   If cmdstr is NULL, sends queued commands. */
int imap_cmd_start (IMAP_DATA* idata, const char* cmdstr)
{
  int rc;

  if (cmdstr && (rc = imap_cmd_queue (idata, cmdstr)) < 0)
    return rc;

  /* don't write old or empty commands */
  if (idata->cmdbuf->dptr == idata->cmdbuf->data)
    return IMAP_CMD_BAD;

  rc = mutt_socket_write (idata->conn, idata->cmdbuf->data);
  idata->cmdbuf->dptr = idata->cmdbuf->data;

  return (rc < 0) ? IMAP_CMD_BAD : 0;
}

/* imap_cmd_step: Reads server responses from an IMAP command, detects
 *   tagged completion response, handles untagged messages, can read
 *   arbitrarily large strings (using malloc, so don't make it _too_
 *   large!). */
int imap_cmd_step (IMAP_DATA* idata)
{
  size_t len = 0;
  int c;
  int rc;

  if (idata->status == IMAP_FATAL)
  {
    cmd_handle_fatal (idata);
    return IMAP_CMD_BAD;
  }

  /* read into buffer, expanding buffer as necessary until we have a full
   * line */
  do
  {
    if (len == idata->blen)
    {
      safe_realloc (&idata->buf, idata->blen + IMAP_CMD_BUFSIZE);
      idata->blen = idata->blen + IMAP_CMD_BUFSIZE;
      dprint (3, (debugfile, "imap_cmd_step: grew buffer to %u bytes\n",
		  idata->blen));
    }

    /* back up over '\0' */
    if (len)
      len--;
    c = mutt_socket_readln (idata->buf + len, idata->blen - len, idata->conn);
    if (c <= 0)
    {
      dprint (1, (debugfile, "imap_cmd_step: Error reading server response.\n"));
      cmd_handle_fatal (idata);
      return IMAP_CMD_BAD;
    }

    len += c;
  }
  /* if we've read all the way to the end of the buffer, we haven't read a
   * full line (mutt_socket_readln strips the \r, so we always have at least
   * one character free when we've read a full line) */
  while (len == idata->blen);

  /* don't let one large string make cmd->buf hog memory forever */
  if ((idata->blen > IMAP_CMD_BUFSIZE) && (len <= IMAP_CMD_BUFSIZE))
  {
    safe_realloc (&idata->buf, IMAP_CMD_BUFSIZE);
    idata->blen = IMAP_CMD_BUFSIZE;
    dprint (3, (debugfile, "imap_cmd_step: shrank buffer to %u bytes\n", idata->blen));
  }

  idata->lastread = time (NULL);

  /* handle untagged messages. The caller still gets its shot afterwards. */
  if (!ascii_strncmp (idata->buf, "* ", 2) &&
      cmd_handle_untagged (idata))
    return IMAP_CMD_BAD;

  /* server demands a continuation response from us */
  if (idata->buf[0] == '+')
    return IMAP_CMD_RESPOND;

  /* tagged completion code. TODO: I believe commands will always be completed
   * in order, but will have to double-check when I have net again */
  rc = IMAP_CMD_CONTINUE;
  if (!ascii_strncmp (idata->buf, idata->cmds[idata->lastcmd].seq, SEQLEN))
  {
    idata->cmds[idata->lastcmd].state = cmd_status (idata->buf);
    idata->lastcmd = (idata->lastcmd + 1) % IMAP_PIPELINE_DEPTH;
    if (idata->lastcmd == idata->nextcmd)
    {
      rc = cmd_status (idata->buf);
      imap_cmd_finish (idata);
    }
  }

  return rc;
}

/* imap_code: returns 1 if the command result was OK, or 0 if NO or BAD */
int imap_code (const char *s)
{
  return cmd_status (s) == IMAP_CMD_OK;
}

/* imap_exec: execute a command, and wait for the response from the server.
 * Also, handle untagged responses.
 * Flags:
 *   IMAP_CMD_FAIL_OK: the calling procedure can handle failure. This is used
 *     for checking for a mailbox on append and login
 *   IMAP_CMD_PASS: command contains a password. Suppress logging.
 * Return 0 on success, -1 on Failure, -2 on OK Failure
 */
int imap_exec (IMAP_DATA* idata, const char* cmdstr, int flags)
{
  int rc;

  if (idata->status == IMAP_FATAL)
  {
    cmd_handle_fatal (idata);
    return -1;
  }

  if (cmdstr && (rc = imap_cmd_queue (idata, cmdstr)) < 0)
    return rc;
  
  /* don't write old or empty commands */
  if (idata->cmdbuf->dptr == idata->cmdbuf->data)
    return IMAP_CMD_BAD;
  
  rc = mutt_socket_write_d (idata->conn, idata->cmdbuf->data, -1,
    flags & IMAP_CMD_PASS ? IMAP_LOG_PASS : IMAP_LOG_CMD);
  idata->cmdbuf->dptr = idata->cmdbuf->data;

  if (rc < 0)
  {
    cmd_handle_fatal (idata);
    return -1;
  }

  do
    rc = imap_cmd_step (idata);
  while (rc == IMAP_CMD_CONTINUE);

  if (rc == IMAP_CMD_NO && (flags & IMAP_CMD_FAIL_OK))
    return -2;

  if (rc != IMAP_CMD_OK)
  {
    if (flags & IMAP_CMD_FAIL_OK)
      return -2;

    dprint (1, (debugfile, "imap_exec: command failed: %s\n", idata->buf));
    return -1;
  }

  return 0;
}

/* imap_cmd_finish: Attempts to perform cleanup (eg fetch new mail if
 *   detected, do expunge). Called automatically by imap_cmd_step, but
 *   may be called at any time. Called by imap_check_mailbox just before
 *   the index is refreshed, for instance. */
void imap_cmd_finish (IMAP_DATA* idata)
{
  if (idata->status == IMAP_FATAL)
  {
    cmd_handle_fatal (idata);
    return;
  }

  if (!(idata->state >= IMAP_SELECTED) || idata->ctx->closing)
    return;
  
  if (idata->reopen & IMAP_REOPEN_ALLOW)
  {
    int count = idata->newMailCount;

    if (!(idata->reopen & IMAP_EXPUNGE_PENDING) &&
	(idata->reopen & IMAP_NEWMAIL_PENDING)
	&& count > idata->ctx->msgcount)
    {
      /* read new mail messages */
      dprint (2, (debugfile, "imap_cmd_finish: Fetching new mail\n"));
      /* check_status: curs_main uses imap_check_mailbox to detect
       *   whether the index needs updating */
      idata->check_status = IMAP_NEWMAIL_PENDING;
      imap_read_headers (idata, idata->ctx->msgcount, count-1);
    }
    else if (idata->reopen & IMAP_EXPUNGE_PENDING)
    {
      dprint (2, (debugfile, "imap_cmd_finish: Expunging mailbox\n"));
      imap_expunge_mailbox (idata);
      /* Detect whether we've gotten unexpected EXPUNGE messages */
      if (idata->reopen & IMAP_EXPUNGE_PENDING &&
	  !(idata->reopen & IMAP_EXPUNGE_EXPECTED))
	idata->check_status = IMAP_EXPUNGE_PENDING;
      idata->reopen &= ~(IMAP_EXPUNGE_PENDING | IMAP_NEWMAIL_PENDING |
			 IMAP_EXPUNGE_EXPECTED);
    }
  }

  idata->status = 0;
}

/* sets up a new command control block and adds it to the queue.
 * Returns NULL if the pipeline is full. */
static IMAP_COMMAND* cmd_new (IMAP_DATA* idata)
{
  IMAP_COMMAND* cmd;

  if ((idata->nextcmd + 1) % IMAP_PIPELINE_DEPTH == idata->lastcmd)
  {
    dprint (2, (debugfile, "cmd_new: IMAP command queue full\n"));
    return NULL;
  }

  cmd = idata->cmds + idata->nextcmd;
  idata->nextcmd = (idata->nextcmd + 1) % IMAP_PIPELINE_DEPTH;

  snprintf (cmd->seq, sizeof (cmd->seq), "a%04u", idata->seqno++);
  if (idata->seqno > 9999)
    idata->seqno = 0;

  cmd->state = IMAP_CMD_NEW;

  return cmd;
}

/* parse response line for tagged OK/NO/BAD */
static int cmd_status (const char *s)
{
  s = imap_next_word((char*)s);
  
  if (!ascii_strncasecmp("OK", s, 2))
    return IMAP_CMD_OK;
  if (!ascii_strncasecmp("NO", s, 2))
    return IMAP_CMD_NO;

  return IMAP_CMD_BAD;
}

/* cmd_handle_fatal: when IMAP_DATA is in fatal state, do what we can */
static void cmd_handle_fatal (IMAP_DATA* idata)
{
  idata->status = IMAP_FATAL;

  if ((idata->state >= IMAP_SELECTED) &&
      (idata->reopen & IMAP_REOPEN_ALLOW))
  {
    mx_fastclose_mailbox (idata->ctx);
    mutt_error (_("Mailbox closed"));
    mutt_sleep (1);
    idata->state = IMAP_DISCONNECTED;
  }

  if (idata->state < IMAP_SELECTED)
  {
    idata->state = IMAP_DISCONNECTED;
    mutt_socket_close (idata->conn);
    idata->status = 0;
  }
}

/* cmd_handle_untagged: fallback parser for otherwise unhandled messages. */
static int cmd_handle_untagged (IMAP_DATA* idata)
{
  char* s;
  char* pn;
  int count;

  s = imap_next_word (idata->buf);

  if ((idata->state >= IMAP_SELECTED) && isdigit ((unsigned char) *s))
  {
    pn = s;
    s = imap_next_word (s);

    /* EXISTS and EXPUNGE are always related to the SELECTED mailbox for the
     * connection, so update that one.
     */
    if (ascii_strncasecmp ("EXISTS", s, 6) == 0)
    {
      dprint (2, (debugfile, "Handling EXISTS\n"));

      /* new mail arrived */
      count = atoi (pn);

      if ( !(idata->reopen & IMAP_EXPUNGE_PENDING) &&
	   count < idata->ctx->msgcount)
      {
	/* something is wrong because the server reported fewer messages
	 * than we previously saw
	 */
	mutt_error _("Fatal error.  Message count is out of sync!");
	idata->status = IMAP_FATAL;
	return -1;
      }
      /* at least the InterChange server sends EXISTS messages freely,
       * even when there is no new mail */
      else if (count == idata->ctx->msgcount)
	dprint (3, (debugfile,
          "cmd_handle_untagged: superfluous EXISTS message.\n"));
      else
      {
	if (!(idata->reopen & IMAP_EXPUNGE_PENDING))
        {
          dprint (2, (debugfile,
            "cmd_handle_untagged: New mail in %s - %d messages total.\n",
            idata->mailbox, count));
	  idata->reopen |= IMAP_NEWMAIL_PENDING;
        }
	idata->newMailCount = count;
      }
    }
    /* pn vs. s: need initial seqno */
    else if (ascii_strncasecmp ("EXPUNGE", s, 7) == 0)
      cmd_parse_expunge (idata, pn);
    else if (ascii_strncasecmp ("FETCH", s, 5) == 0)
      cmd_parse_fetch (idata, pn);
  }
  else if (ascii_strncasecmp ("CAPABILITY", s, 10) == 0)
    cmd_parse_capability (idata, s);
  else if (!ascii_strncasecmp ("OK [CAPABILITY", s, 14))
    cmd_parse_capability (idata, imap_next_word (s));
  else if (ascii_strncasecmp ("LIST", s, 4) == 0)
    cmd_parse_list (idata, s);
  else if (ascii_strncasecmp ("LSUB", s, 4) == 0)
    cmd_parse_lsub (idata, s);
  else if (ascii_strncasecmp ("MYRIGHTS", s, 8) == 0)
    cmd_parse_myrights (idata, s);
  else if (ascii_strncasecmp ("SEARCH", s, 6) == 0)
    cmd_parse_search (idata, s);
  else if (ascii_strncasecmp ("STATUS", s, 6) == 0)
    cmd_parse_status (idata, s);
  else if (ascii_strncasecmp ("BYE", s, 3) == 0)
  {
    dprint (2, (debugfile, "Handling BYE\n"));

    /* check if we're logging out */
    if (idata->status == IMAP_BYE)
      return 0;