--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/curl/lib/imap.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,2105 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2019, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ * RFC2195 CRAM-MD5 authentication
+ * RFC2595 Using TLS with IMAP, POP3 and ACAP
+ * RFC2831 DIGEST-MD5 authentication
+ * RFC3501 IMAPv4 protocol
+ * RFC4422 Simple Authentication and Security Layer (SASL)
+ * RFC4616 PLAIN authentication
+ * RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism
+ * RFC4959 IMAP Extension for SASL Initial Client Response
+ * RFC5092 IMAP URL Scheme
+ * RFC6749 OAuth 2.0 Authorization Framework
+ * RFC8314 Use of TLS for Email Submission and Access
+ * Draft   LOGIN SASL Mechanism <draft-murchison-sasl-login-00.txt>
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#ifndef CURL_DISABLE_IMAP
+
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#ifdef HAVE_ARPA_INET_H
+#include <arpa/inet.h>
+#endif
+#ifdef HAVE_UTSNAME_H
+#include <sys/utsname.h>
+#endif
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+#ifdef __VMS
+#include <in.h>
+#include <inet.h>
+#endif
+
+#if (defined(NETWARE) && defined(__NOVELL_LIBC__))
+#undef in_addr_t
+#define in_addr_t unsigned long
+#endif
+
+#include <curl/curl.h>
+#include "urldata.h"
+#include "sendf.h"
+#include "hostip.h"
+#include "progress.h"
+#include "transfer.h"
+#include "escape.h"
+#include "http.h" /* for HTTP proxy tunnel stuff */
+#include "socks.h"
+#include "imap.h"
+#include "mime.h"
+#include "strtoofft.h"
+#include "strcase.h"
+#include "vtls/vtls.h"
+#include "connect.h"
+#include "strerror.h"
+#include "select.h"
+#include "multiif.h"
+#include "url.h"
+#include "strcase.h"
+#include "curl_sasl.h"
+#include "warnless.h"
+
+/* The last 3 #include files should be in this order */
+#include "curl_printf.h"
+#include "curl_memory.h"
+#include "memdebug.h"
+
+/* Local API functions */
+static CURLcode imap_regular_transfer(struct connectdata *conn, bool *done);
+static CURLcode imap_do(struct connectdata *conn, bool *done);
+static CURLcode imap_done(struct connectdata *conn, CURLcode status,
+                          bool premature);
+static CURLcode imap_connect(struct connectdata *conn, bool *done);
+static CURLcode imap_disconnect(struct connectdata *conn, bool dead);
+static CURLcode imap_multi_statemach(struct connectdata *conn, bool *done);
+static int imap_getsock(struct connectdata *conn, curl_socket_t *socks);
+static CURLcode imap_doing(struct connectdata *conn, bool *dophase_done);
+static CURLcode imap_setup_connection(struct connectdata *conn);
+static char *imap_atom(const char *str, bool escape_only);
+static CURLcode imap_sendf(struct connectdata *conn, const char *fmt, ...);
+static CURLcode imap_parse_url_options(struct connectdata *conn);
+static CURLcode imap_parse_url_path(struct connectdata *conn);
+static CURLcode imap_parse_custom_request(struct connectdata *conn);
+static CURLcode imap_perform_authenticate(struct connectdata *conn,
+                                          const char *mech,
+                                          const char *initresp);
+static CURLcode imap_continue_authenticate(struct connectdata *conn,
+                                           const char *resp);
+static void imap_get_message(char *buffer, char **outptr);
+
+/*
+ * IMAP protocol handler.
+ */
+
+const struct Curl_handler Curl_handler_imap = {
+  "IMAP",                           /* scheme */
+  imap_setup_connection,            /* setup_connection */
+  imap_do,                          /* do_it */
+  imap_done,                        /* done */
+  ZERO_NULL,                        /* do_more */
+  imap_connect,                     /* connect_it */
+  imap_multi_statemach,             /* connecting */
+  imap_doing,                       /* doing */
+  imap_getsock,                     /* proto_getsock */
+  imap_getsock,                     /* doing_getsock */
+  ZERO_NULL,                        /* domore_getsock */
+  ZERO_NULL,                        /* perform_getsock */
+  imap_disconnect,                  /* disconnect */
+  ZERO_NULL,                        /* readwrite */
+  ZERO_NULL,                        /* connection_check */
+  PORT_IMAP,                        /* defport */
+  CURLPROTO_IMAP,                   /* protocol */
+  PROTOPT_CLOSEACTION|              /* flags */
+  PROTOPT_URLOPTIONS
+};
+
+#ifdef USE_SSL
+/*
+ * IMAPS protocol handler.
+ */
+
+const struct Curl_handler Curl_handler_imaps = {
+  "IMAPS",                          /* scheme */
+  imap_setup_connection,            /* setup_connection */
+  imap_do,                          /* do_it */
+  imap_done,                        /* done */
+  ZERO_NULL,                        /* do_more */
+  imap_connect,                     /* connect_it */
+  imap_multi_statemach,             /* connecting */
+  imap_doing,                       /* doing */
+  imap_getsock,                     /* proto_getsock */
+  imap_getsock,                     /* doing_getsock */
+  ZERO_NULL,                        /* domore_getsock */
+  ZERO_NULL,                        /* perform_getsock */
+  imap_disconnect,                  /* disconnect */
+  ZERO_NULL,                        /* readwrite */
+  ZERO_NULL,                        /* connection_check */
+  PORT_IMAPS,                       /* defport */
+  CURLPROTO_IMAPS,                  /* protocol */
+  PROTOPT_CLOSEACTION | PROTOPT_SSL | /* flags */
+  PROTOPT_URLOPTIONS
+};
+#endif
+
+#define IMAP_RESP_OK       1
+#define IMAP_RESP_NOT_OK   2
+#define IMAP_RESP_PREAUTH  3
+
+/* SASL parameters for the imap protocol */
+static const struct SASLproto saslimap = {
+  "imap",                     /* The service name */
+  '+',                        /* Code received when continuation is expected */
+  IMAP_RESP_OK,               /* Code to receive upon authentication success */
+  0,                          /* Maximum initial response length (no max) */
+  imap_perform_authenticate,  /* Send authentication command */
+  imap_continue_authenticate, /* Send authentication continuation */
+  imap_get_message            /* Get SASL response message */
+};
+
+
+#ifdef USE_SSL
+static void imap_to_imaps(struct connectdata *conn)
+{
+  /* Change the connection handler */
+  conn->handler = &Curl_handler_imaps;
+
+  /* Set the connection's upgraded to TLS flag */
+  conn->tls_upgraded = TRUE;
+}
+#else
+#define imap_to_imaps(x) Curl_nop_stmt
+#endif
+
+/***********************************************************************
+ *
+ * imap_matchresp()
+ *
+ * Determines whether the untagged response is related to the specified
+ * command by checking if it is in format "* <command-name> ..." or
+ * "* <number> <command-name> ...".
+ *
+ * The "* " marker is assumed to have already been checked by the caller.
+ */
+static bool imap_matchresp(const char *line, size_t len, const char *cmd)
+{
+  const char *end = line + len;
+  size_t cmd_len = strlen(cmd);
+
+  /* Skip the untagged response marker */
+  line += 2;
+
+  /* Do we have a number after the marker? */
+  if(line < end && ISDIGIT(*line)) {
+    /* Skip the number */
+    do
+      line++;
+    while(line < end && ISDIGIT(*line));
+
+    /* Do we have the space character? */
+    if(line == end || *line != ' ')
+      return FALSE;
+
+    line++;
+  }
+
+  /* Does the command name match and is it followed by a space character or at
+     the end of line? */
+  if(line + cmd_len <= end && strncasecompare(line, cmd, cmd_len) &&
+     (line[cmd_len] == ' ' || line + cmd_len + 2 == end))
+    return TRUE;
+
+  return FALSE;
+}
+
+/***********************************************************************
+ *
+ * imap_endofresp()
+ *
+ * Checks whether the given string is a valid tagged, untagged or continuation
+ * response which can be processed by the response handler.
+ */
+static bool imap_endofresp(struct connectdata *conn, char *line, size_t len,
+                           int *resp)
+{
+  struct IMAP *imap = conn->data->req.protop;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  const char *id = imapc->resptag;
+  size_t id_len = strlen(id);
+
+  /* Do we have a tagged command response? */
+  if(len >= id_len + 1 && !memcmp(id, line, id_len) && line[id_len] == ' ') {
+    line += id_len + 1;
+    len -= id_len + 1;
+
+    if(len >= 2 && !memcmp(line, "OK", 2))
+      *resp = IMAP_RESP_OK;
+    else if(len >= 7 && !memcmp(line, "PREAUTH", 7))
+      *resp = IMAP_RESP_PREAUTH;
+    else
+      *resp = IMAP_RESP_NOT_OK;
+
+    return TRUE;
+  }
+
+  /* Do we have an untagged command response? */
+  if(len >= 2 && !memcmp("* ", line, 2)) {
+    switch(imapc->state) {
+      /* States which are interested in untagged responses */
+      case IMAP_CAPABILITY:
+        if(!imap_matchresp(line, len, "CAPABILITY"))
+          return FALSE;
+        break;
+
+      case IMAP_LIST:
+        if((!imap->custom && !imap_matchresp(line, len, "LIST")) ||
+          (imap->custom && !imap_matchresp(line, len, imap->custom) &&
+           (!strcasecompare(imap->custom, "STORE") ||
+            !imap_matchresp(line, len, "FETCH")) &&
+           !strcasecompare(imap->custom, "SELECT") &&
+           !strcasecompare(imap->custom, "EXAMINE") &&
+           !strcasecompare(imap->custom, "SEARCH") &&
+           !strcasecompare(imap->custom, "EXPUNGE") &&
+           !strcasecompare(imap->custom, "LSUB") &&
+           !strcasecompare(imap->custom, "UID") &&
+           !strcasecompare(imap->custom, "NOOP")))
+          return FALSE;
+        break;
+
+      case IMAP_SELECT:
+        /* SELECT is special in that its untagged responses do not have a
+           common prefix so accept anything! */
+        break;
+
+      case IMAP_FETCH:
+        if(!imap_matchresp(line, len, "FETCH"))
+          return FALSE;
+        break;
+
+      case IMAP_SEARCH:
+        if(!imap_matchresp(line, len, "SEARCH"))
+          return FALSE;
+        break;
+
+      /* Ignore other untagged responses */
+      default:
+        return FALSE;
+    }
+
+    *resp = '*';
+    return TRUE;
+  }
+
+  /* Do we have a continuation response? This should be a + symbol followed by
+     a space and optionally some text as per RFC-3501 for the AUTHENTICATE and
+     APPEND commands and as outlined in Section 4. Examples of RFC-4959 but
+     some e-mail servers ignore this and only send a single + instead. */
+  if(imap && !imap->custom && ((len == 3 && line[0] == '+') ||
+     (len >= 2 && !memcmp("+ ", line, 2)))) {
+    switch(imapc->state) {
+      /* States which are interested in continuation responses */
+      case IMAP_AUTHENTICATE:
+      case IMAP_APPEND:
+        *resp = '+';
+        break;
+
+      default:
+        failf(conn->data, "Unexpected continuation response");
+        *resp = -1;
+        break;
+    }
+
+    return TRUE;
+  }
+
+  return FALSE; /* Nothing for us */
+}
+
+/***********************************************************************
+ *
+ * imap_get_message()
+ *
+ * Gets the authentication message from the response buffer.
+ */
+static void imap_get_message(char *buffer, char **outptr)
+{
+  size_t len = strlen(buffer);
+  char *message = NULL;
+
+  if(len > 2) {
+    /* Find the start of the message */
+    len -= 2;
+    for(message = buffer + 2; *message == ' ' || *message == '\t';
+        message++, len--)
+      ;
+
+    /* Find the end of the message */
+    for(; len--;)
+      if(message[len] != '\r' && message[len] != '\n' && message[len] != ' ' &&
+         message[len] != '\t')
+        break;
+
+    /* Terminate the message */
+    if(++len) {
+      message[len] = '\0';
+    }
+  }
+  else
+    /* junk input => zero length output */
+    message = &buffer[len];
+
+  *outptr = message;
+}
+
+/***********************************************************************
+ *
+ * state()
+ *
+ * This is the ONLY way to change IMAP state!
+ */
+static void state(struct connectdata *conn, imapstate newstate)
+{
+  struct imap_conn *imapc = &conn->proto.imapc;
+#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
+  /* for debug purposes */
+  static const char * const names[]={
+    "STOP",
+    "SERVERGREET",
+    "CAPABILITY",
+    "STARTTLS",
+    "UPGRADETLS",
+    "AUTHENTICATE",
+    "LOGIN",
+    "LIST",
+    "SELECT",
+    "FETCH",
+    "FETCH_FINAL",
+    "APPEND",
+    "APPEND_FINAL",
+    "SEARCH",
+    "LOGOUT",
+    /* LAST */
+  };
+
+  if(imapc->state != newstate)
+    infof(conn->data, "IMAP %p state change from %s to %s\n",
+          (void *)imapc, names[imapc->state], names[newstate]);
+#endif
+
+  imapc->state = newstate;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_capability()
+ *
+ * Sends the CAPABILITY command in order to obtain a list of server side
+ * supported capabilities.
+ */
+static CURLcode imap_perform_capability(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  imapc->sasl.authmechs = SASL_AUTH_NONE; /* No known auth. mechanisms yet */
+  imapc->sasl.authused = SASL_AUTH_NONE;  /* Clear the auth. mechanism used */
+  imapc->tls_supported = FALSE;           /* Clear the TLS capability */
+
+  /* Send the CAPABILITY command */
+  result = imap_sendf(conn, "CAPABILITY");
+
+  if(!result)
+    state(conn, IMAP_CAPABILITY);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_starttls()
+ *
+ * Sends the STARTTLS command to start the upgrade to TLS.
+ */
+static CURLcode imap_perform_starttls(struct connectdata *conn)
+{
+  /* Send the STARTTLS command */
+  CURLcode result = imap_sendf(conn, "STARTTLS");
+
+  if(!result)
+    state(conn, IMAP_STARTTLS);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_upgrade_tls()
+ *
+ * Performs the upgrade to TLS.
+ */
+static CURLcode imap_perform_upgrade_tls(struct connectdata *conn)
+{
+  /* Start the SSL connection */
+  struct imap_conn *imapc = &conn->proto.imapc;
+  CURLcode result = Curl_ssl_connect_nonblocking(conn, FIRSTSOCKET,
+                                                 &imapc->ssldone);
+
+  if(!result) {
+    if(imapc->state != IMAP_UPGRADETLS)
+      state(conn, IMAP_UPGRADETLS);
+
+    if(imapc->ssldone) {
+      imap_to_imaps(conn);
+      result = imap_perform_capability(conn);
+    }
+  }
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_login()
+ *
+ * Sends a clear text LOGIN command to authenticate with.
+ */
+static CURLcode imap_perform_login(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  char *user;
+  char *passwd;
+
+  /* Check we have a username and password to authenticate with and end the
+     connect phase if we don't */
+  if(!conn->bits.user_passwd) {
+    state(conn, IMAP_STOP);
+
+    return result;
+  }
+
+  /* Make sure the username and password are in the correct atom format */
+  user = imap_atom(conn->user, false);
+  passwd = imap_atom(conn->passwd, false);
+
+  /* Send the LOGIN command */
+  result = imap_sendf(conn, "LOGIN %s %s", user ? user : "",
+                      passwd ? passwd : "");
+
+  free(user);
+  free(passwd);
+
+  if(!result)
+    state(conn, IMAP_LOGIN);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_authenticate()
+ *
+ * Sends an AUTHENTICATE command allowing the client to login with the given
+ * SASL authentication mechanism.
+ */
+static CURLcode imap_perform_authenticate(struct connectdata *conn,
+                                          const char *mech,
+                                          const char *initresp)
+{
+  CURLcode result = CURLE_OK;
+
+  if(initresp) {
+    /* Send the AUTHENTICATE command with the initial response */
+    result = imap_sendf(conn, "AUTHENTICATE %s %s", mech, initresp);
+  }
+  else {
+    /* Send the AUTHENTICATE command */
+    result = imap_sendf(conn, "AUTHENTICATE %s", mech);
+  }
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_continue_authenticate()
+ *
+ * Sends SASL continuation data or cancellation.
+ */
+static CURLcode imap_continue_authenticate(struct connectdata *conn,
+                                           const char *resp)
+{
+  struct imap_conn *imapc = &conn->proto.imapc;
+
+  return Curl_pp_sendf(&imapc->pp, "%s", resp);
+}
+
+/***********************************************************************
+ *
+ * imap_perform_authentication()
+ *
+ * Initiates the authentication sequence, with the appropriate SASL
+ * authentication mechanism, falling back to clear text should a common
+ * mechanism not be available between the client and server.
+ */
+static CURLcode imap_perform_authentication(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  saslprogress progress;
+
+  /* Check if already authenticated OR if there is enough data to authenticate
+     with and end the connect phase if we don't */
+  if(imapc->preauth ||
+     !Curl_sasl_can_authenticate(&imapc->sasl, conn)) {
+    state(conn, IMAP_STOP);
+    return result;
+  }
+
+  /* Calculate the SASL login details */
+  result = Curl_sasl_start(&imapc->sasl, conn, imapc->ir_supported, &progress);
+
+  if(!result) {
+    if(progress == SASL_INPROGRESS)
+      state(conn, IMAP_AUTHENTICATE);
+    else if(!imapc->login_disabled && (imapc->preftype & IMAP_TYPE_CLEARTEXT))
+      /* Perform clear text authentication */
+      result = imap_perform_login(conn);
+    else {
+      /* Other mechanisms not supported */
+      infof(conn->data, "No known authentication mechanisms supported!\n");
+      result = CURLE_LOGIN_DENIED;
+    }
+  }
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_list()
+ *
+ * Sends a LIST command or an alternative custom request.
+ */
+static CURLcode imap_perform_list(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct IMAP *imap = data->req.protop;
+
+  if(imap->custom)
+    /* Send the custom request */
+    result = imap_sendf(conn, "%s%s", imap->custom,
+                        imap->custom_params ? imap->custom_params : "");
+  else {
+    /* Make sure the mailbox is in the correct atom format if necessary */
+    char *mailbox = imap->mailbox ? imap_atom(imap->mailbox, true)
+                                  : strdup("");
+    if(!mailbox)
+      return CURLE_OUT_OF_MEMORY;
+
+    /* Send the LIST command */
+    result = imap_sendf(conn, "LIST \"%s\" *", mailbox);
+
+    free(mailbox);
+  }
+
+  if(!result)
+    state(conn, IMAP_LIST);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_select()
+ *
+ * Sends a SELECT command to ask the server to change the selected mailbox.
+ */
+static CURLcode imap_perform_select(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct IMAP *imap = data->req.protop;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  char *mailbox;
+
+  /* Invalidate old information as we are switching mailboxes */
+  Curl_safefree(imapc->mailbox);
+  Curl_safefree(imapc->mailbox_uidvalidity);
+
+  /* Check we have a mailbox */
+  if(!imap->mailbox) {
+    failf(conn->data, "Cannot SELECT without a mailbox.");
+    return CURLE_URL_MALFORMAT;
+  }
+
+  /* Make sure the mailbox is in the correct atom format */
+  mailbox = imap_atom(imap->mailbox, false);
+  if(!mailbox)
+    return CURLE_OUT_OF_MEMORY;
+
+  /* Send the SELECT command */
+  result = imap_sendf(conn, "SELECT %s", mailbox);
+
+  free(mailbox);
+
+  if(!result)
+    state(conn, IMAP_SELECT);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_fetch()
+ *
+ * Sends a FETCH command to initiate the download of a message.
+ */
+static CURLcode imap_perform_fetch(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct IMAP *imap = conn->data->req.protop;
+  /* Check we have a UID */
+  if(imap->uid) {
+
+    /* Send the FETCH command */
+    if(imap->partial)
+      result = imap_sendf(conn, "UID FETCH %s BODY[%s]<%s>",
+                            imap->uid,
+                            imap->section ? imap->section : "",
+                            imap->partial);
+    else
+      result = imap_sendf(conn, "UID FETCH %s BODY[%s]",
+                            imap->uid,
+                            imap->section ? imap->section : "");
+  }
+  else if(imap->mindex) {
+
+    /* Send the FETCH command */
+    if(imap->partial)
+      result = imap_sendf(conn, "FETCH %s BODY[%s]<%s>",
+                            imap->mindex,
+                            imap->section ? imap->section : "",
+                            imap->partial);
+    else
+      result = imap_sendf(conn, "FETCH %s BODY[%s]",
+                            imap->mindex,
+                            imap->section ? imap->section : "");
+  }
+  else {
+        failf(conn->data, "Cannot FETCH without a UID.");
+        return CURLE_URL_MALFORMAT;
+  }
+  if(!result)
+    state(conn, IMAP_FETCH);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_append()
+ *
+ * Sends an APPEND command to initiate the upload of a message.
+ */
+static CURLcode imap_perform_append(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct IMAP *imap = data->req.protop;
+  char *mailbox;
+
+  /* Check we have a mailbox */
+  if(!imap->mailbox) {
+    failf(data, "Cannot APPEND without a mailbox.");
+    return CURLE_URL_MALFORMAT;
+  }
+
+  /* Prepare the mime data if some. */
+  if(data->set.mimepost.kind != MIMEKIND_NONE) {
+    /* Use the whole structure as data. */
+    data->set.mimepost.flags &= ~MIME_BODY_ONLY;
+
+    /* Add external headers and mime version. */
+    curl_mime_headers(&data->set.mimepost, data->set.headers, 0);
+    result = Curl_mime_prepare_headers(&data->set.mimepost, NULL,
+                                       NULL, MIMESTRATEGY_MAIL);
+
+    if(!result)
+      if(!Curl_checkheaders(conn, "Mime-Version"))
+        result = Curl_mime_add_header(&data->set.mimepost.curlheaders,
+                                      "Mime-Version: 1.0");
+
+    /* Make sure we will read the entire mime structure. */
+    if(!result)
+      result = Curl_mime_rewind(&data->set.mimepost);
+
+    if(result)
+      return result;
+
+    data->state.infilesize = Curl_mime_size(&data->set.mimepost);
+
+    /* Read from mime structure. */
+    data->state.fread_func = (curl_read_callback) Curl_mime_read;
+    data->state.in = (void *) &data->set.mimepost;
+  }
+
+  /* Check we know the size of the upload */
+  if(data->state.infilesize < 0) {
+    failf(data, "Cannot APPEND with unknown input file size\n");
+    return CURLE_UPLOAD_FAILED;
+  }
+
+  /* Make sure the mailbox is in the correct atom format */
+  mailbox = imap_atom(imap->mailbox, false);
+  if(!mailbox)
+    return CURLE_OUT_OF_MEMORY;
+
+  /* Send the APPEND command */
+  result = imap_sendf(conn, "APPEND %s (\\Seen) {%" CURL_FORMAT_CURL_OFF_T "}",
+                      mailbox, data->state.infilesize);
+
+  free(mailbox);
+
+  if(!result)
+    state(conn, IMAP_APPEND);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_search()
+ *
+ * Sends a SEARCH command.
+ */
+static CURLcode imap_perform_search(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct IMAP *imap = conn->data->req.protop;
+
+  /* Check we have a query string */
+  if(!imap->query) {
+    failf(conn->data, "Cannot SEARCH without a query string.");
+    return CURLE_URL_MALFORMAT;
+  }
+
+  /* Send the SEARCH command */
+  result = imap_sendf(conn, "SEARCH %s", imap->query);
+
+  if(!result)
+    state(conn, IMAP_SEARCH);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform_logout()
+ *
+ * Performs the logout action prior to sclose() being called.
+ */
+static CURLcode imap_perform_logout(struct connectdata *conn)
+{
+  /* Send the LOGOUT command */
+  CURLcode result = imap_sendf(conn, "LOGOUT");
+
+  if(!result)
+    state(conn, IMAP_LOGOUT);
+
+  return result;
+}
+
+/* For the initial server greeting */
+static CURLcode imap_state_servergreet_resp(struct connectdata *conn,
+                                            int imapcode,
+                                            imapstate instate)
+{
+  struct Curl_easy *data = conn->data;
+  (void)instate; /* no use for this yet */
+
+  if(imapcode == IMAP_RESP_PREAUTH) {
+    /* PREAUTH */
+    struct imap_conn *imapc = &conn->proto.imapc;
+    imapc->preauth = TRUE;
+    infof(data, "PREAUTH connection, already authenticated!\n");
+  }
+  else if(imapcode != IMAP_RESP_OK) {
+    failf(data, "Got unexpected imap-server response");
+    return CURLE_WEIRD_SERVER_REPLY;
+  }
+
+  return imap_perform_capability(conn);
+}
+
+/* For CAPABILITY responses */
+static CURLcode imap_state_capability_resp(struct connectdata *conn,
+                                           int imapcode,
+                                           imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  const char *line = data->state.buffer;
+
+  (void)instate; /* no use for this yet */
+
+  /* Do we have a untagged response? */
+  if(imapcode == '*') {
+    line += 2;
+
+    /* Loop through the data line */
+    for(;;) {
+      size_t wordlen;
+      while(*line &&
+            (*line == ' ' || *line == '\t' ||
+              *line == '\r' || *line == '\n')) {
+
+        line++;
+      }
+
+      if(!*line)
+        break;
+
+      /* Extract the word */
+      for(wordlen = 0; line[wordlen] && line[wordlen] != ' ' &&
+            line[wordlen] != '\t' && line[wordlen] != '\r' &&
+            line[wordlen] != '\n';)
+        wordlen++;
+
+      /* Does the server support the STARTTLS capability? */
+      if(wordlen == 8 && !memcmp(line, "STARTTLS", 8))
+        imapc->tls_supported = TRUE;
+
+      /* Has the server explicitly disabled clear text authentication? */
+      else if(wordlen == 13 && !memcmp(line, "LOGINDISABLED", 13))
+        imapc->login_disabled = TRUE;
+
+      /* Does the server support the SASL-IR capability? */
+      else if(wordlen == 7 && !memcmp(line, "SASL-IR", 7))
+        imapc->ir_supported = TRUE;
+
+      /* Do we have a SASL based authentication mechanism? */
+      else if(wordlen > 5 && !memcmp(line, "AUTH=", 5)) {
+        size_t llen;
+        unsigned int mechbit;
+
+        line += 5;
+        wordlen -= 5;
+
+        /* Test the word for a matching authentication mechanism */
+        mechbit = Curl_sasl_decode_mech(line, wordlen, &llen);
+        if(mechbit && llen == wordlen)
+          imapc->sasl.authmechs |= mechbit;
+      }
+
+      line += wordlen;
+    }
+  }
+  else if(imapcode == IMAP_RESP_OK) {
+    if(data->set.use_ssl && !conn->ssl[FIRSTSOCKET].use) {
+      /* We don't have a SSL/TLS connection yet, but SSL is requested */
+      if(imapc->tls_supported)
+        /* Switch to TLS connection now */
+        result = imap_perform_starttls(conn);
+      else if(data->set.use_ssl == CURLUSESSL_TRY)
+        /* Fallback and carry on with authentication */
+        result = imap_perform_authentication(conn);
+      else {
+        failf(data, "STARTTLS not supported.");
+        result = CURLE_USE_SSL_FAILED;
+      }
+    }
+    else
+      result = imap_perform_authentication(conn);
+  }
+  else
+    result = imap_perform_authentication(conn);
+
+  return result;
+}
+
+/* For STARTTLS responses */
+static CURLcode imap_state_starttls_resp(struct connectdata *conn,
+                                         int imapcode,
+                                         imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+
+  (void)instate; /* no use for this yet */
+
+  if(imapcode != IMAP_RESP_OK) {
+    if(data->set.use_ssl != CURLUSESSL_TRY) {
+      failf(data, "STARTTLS denied");
+      result = CURLE_USE_SSL_FAILED;
+    }
+    else
+      result = imap_perform_authentication(conn);
+  }
+  else
+    result = imap_perform_upgrade_tls(conn);
+
+  return result;
+}
+
+/* For SASL authentication responses */
+static CURLcode imap_state_auth_resp(struct connectdata *conn,
+                                     int imapcode,
+                                     imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  saslprogress progress;
+
+  (void)instate; /* no use for this yet */
+
+  result = Curl_sasl_continue(&imapc->sasl, conn, imapcode, &progress);
+  if(!result)
+    switch(progress) {
+    case SASL_DONE:
+      state(conn, IMAP_STOP);  /* Authenticated */
+      break;
+    case SASL_IDLE:            /* No mechanism left after cancellation */
+      if((!imapc->login_disabled) && (imapc->preftype & IMAP_TYPE_CLEARTEXT))
+        /* Perform clear text authentication */
+        result = imap_perform_login(conn);
+      else {
+        failf(data, "Authentication cancelled");
+        result = CURLE_LOGIN_DENIED;
+      }
+      break;
+    default:
+      break;
+    }
+
+  return result;
+}
+
+/* For LOGIN responses */
+static CURLcode imap_state_login_resp(struct connectdata *conn,
+                                      int imapcode,
+                                      imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+
+  (void)instate; /* no use for this yet */
+
+  if(imapcode != IMAP_RESP_OK) {
+    failf(data, "Access denied. %c", imapcode);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else
+    /* End of connect phase */
+    state(conn, IMAP_STOP);
+
+  return result;
+}
+
+/* For LIST and SEARCH responses */
+static CURLcode imap_state_listsearch_resp(struct connectdata *conn,
+                                           int imapcode,
+                                           imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+  char *line = conn->data->state.buffer;
+  size_t len = strlen(line);
+
+  (void)instate; /* No use for this yet */
+
+  if(imapcode == '*') {
+    /* Temporarily add the LF character back and send as body to the client */
+    line[len] = '\n';
+    result = Curl_client_write(conn, CLIENTWRITE_BODY, line, len + 1);
+    line[len] = '\0';
+  }
+  else if(imapcode != IMAP_RESP_OK)
+    result = CURLE_QUOTE_ERROR;
+  else
+    /* End of DO phase */
+    state(conn, IMAP_STOP);
+
+  return result;
+}
+
+/* For SELECT responses */
+static CURLcode imap_state_select_resp(struct connectdata *conn, int imapcode,
+                                       imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct IMAP *imap = conn->data->req.protop;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  const char *line = data->state.buffer;
+
+  (void)instate; /* no use for this yet */
+
+  if(imapcode == '*') {
+    /* See if this is an UIDVALIDITY response */
+    char tmp[20];
+    if(sscanf(line + 2, "OK [UIDVALIDITY %19[0123456789]]", tmp) == 1) {
+      Curl_safefree(imapc->mailbox_uidvalidity);
+      imapc->mailbox_uidvalidity = strdup(tmp);
+    }
+  }
+  else if(imapcode == IMAP_RESP_OK) {
+    /* Check if the UIDVALIDITY has been specified and matches */
+    if(imap->uidvalidity && imapc->mailbox_uidvalidity &&
+       !strcasecompare(imap->uidvalidity, imapc->mailbox_uidvalidity)) {
+      failf(conn->data, "Mailbox UIDVALIDITY has changed");
+      result = CURLE_REMOTE_FILE_NOT_FOUND;
+    }
+    else {
+      /* Note the currently opened mailbox on this connection */
+      imapc->mailbox = strdup(imap->mailbox);
+
+      if(imap->custom)
+        result = imap_perform_list(conn);
+      else if(imap->query)
+        result = imap_perform_search(conn);
+      else
+        result = imap_perform_fetch(conn);
+    }
+  }
+  else {
+    failf(data, "Select failed");
+    result = CURLE_LOGIN_DENIED;
+  }
+
+  return result;
+}
+
+/* For the (first line of the) FETCH responses */
+static CURLcode imap_state_fetch_resp(struct connectdata *conn, int imapcode,
+                                      imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  struct pingpong *pp = &imapc->pp;
+  const char *ptr = data->state.buffer;
+  bool parsed = FALSE;
+  curl_off_t size = 0;
+
+  (void)instate; /* no use for this yet */
+
+  if(imapcode != '*') {
+    Curl_pgrsSetDownloadSize(data, -1);
+    state(conn, IMAP_STOP);
+    return CURLE_REMOTE_FILE_NOT_FOUND;
+  }
+
+  /* Something like this is received "* 1 FETCH (BODY[TEXT] {2021}\r" so parse
+     the continuation data contained within the curly brackets */
+  while(*ptr && (*ptr != '{'))
+    ptr++;
+
+  if(*ptr == '{') {
+    char *endptr;
+    if(!curlx_strtoofft(ptr + 1, &endptr, 10, &size)) {
+      if(endptr - ptr > 1 && endptr[0] == '}' &&
+         endptr[1] == '\r' && endptr[2] == '\0')
+        parsed = TRUE;
+    }
+  }
+
+  if(parsed) {
+    infof(data, "Found %" CURL_FORMAT_CURL_OFF_T " bytes to download\n",
+          size);
+    Curl_pgrsSetDownloadSize(data, size);
+
+    if(pp->cache) {
+      /* At this point there is a bunch of data in the header "cache" that is
+         actually body content, send it as body and then skip it. Do note
+         that there may even be additional "headers" after the body. */
+      size_t chunk = pp->cache_size;
+
+      if(chunk > (size_t)size)
+        /* The conversion from curl_off_t to size_t is always fine here */
+        chunk = (size_t)size;
+
+      if(!chunk) {
+        /* no size, we're done with the data */
+        state(conn, IMAP_STOP);
+        return CURLE_OK;
+      }
+      result = Curl_client_write(conn, CLIENTWRITE_BODY, pp->cache, chunk);
+      if(result)
+        return result;
+
+      data->req.bytecount += chunk;
+
+      infof(data, "Written %zu bytes, %" CURL_FORMAT_CURL_OFF_TU
+            " bytes are left for transfer\n", chunk, size - chunk);
+
+      /* Have we used the entire cache or just part of it?*/
+      if(pp->cache_size > chunk) {
+        /* Only part of it so shrink the cache to fit the trailing data */
+        memmove(pp->cache, pp->cache + chunk, pp->cache_size - chunk);
+        pp->cache_size -= chunk;
+      }
+      else {
+        /* Free the cache */
+        Curl_safefree(pp->cache);
+
+        /* Reset the cache size */
+        pp->cache_size = 0;
+      }
+    }
+
+    if(data->req.bytecount == size)
+      /* The entire data is already transferred! */
+      Curl_setup_transfer(data, -1, -1, FALSE, -1);
+    else {
+      /* IMAP download */
+      data->req.maxdownload = size;
+      Curl_setup_transfer(data, FIRSTSOCKET, size, FALSE, -1);
+    }
+  }
+  else {
+    /* We don't know how to parse this line */
+    failf(pp->conn->data, "Failed to parse FETCH response.");
+    result = CURLE_WEIRD_SERVER_REPLY;
+  }
+
+  /* End of DO phase */
+  state(conn, IMAP_STOP);
+
+  return result;
+}
+
+/* For final FETCH responses performed after the download */
+static CURLcode imap_state_fetch_final_resp(struct connectdata *conn,
+                                            int imapcode,
+                                            imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+
+  (void)instate; /* No use for this yet */
+
+  if(imapcode != IMAP_RESP_OK)
+    result = CURLE_WEIRD_SERVER_REPLY;
+  else
+    /* End of DONE phase */
+    state(conn, IMAP_STOP);
+
+  return result;
+}
+
+/* For APPEND responses */
+static CURLcode imap_state_append_resp(struct connectdata *conn, int imapcode,
+                                       imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+
+  (void)instate; /* No use for this yet */
+
+  if(imapcode != '+') {
+    result = CURLE_UPLOAD_FAILED;
+  }
+  else {
+    /* Set the progress upload size */
+    Curl_pgrsSetUploadSize(data, data->state.infilesize);
+
+    /* IMAP upload */
+    Curl_setup_transfer(data, -1, -1, FALSE, FIRSTSOCKET);
+
+    /* End of DO phase */
+    state(conn, IMAP_STOP);
+  }
+
+  return result;
+}
+
+/* For final APPEND responses performed after the upload */
+static CURLcode imap_state_append_final_resp(struct connectdata *conn,
+                                             int imapcode,
+                                             imapstate instate)
+{
+  CURLcode result = CURLE_OK;
+
+  (void)instate; /* No use for this yet */
+
+  if(imapcode != IMAP_RESP_OK)
+    result = CURLE_UPLOAD_FAILED;
+  else
+    /* End of DONE phase */
+    state(conn, IMAP_STOP);
+
+  return result;
+}
+
+static CURLcode imap_statemach_act(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  curl_socket_t sock = conn->sock[FIRSTSOCKET];
+  int imapcode;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  struct pingpong *pp = &imapc->pp;
+  size_t nread = 0;
+
+  /* Busy upgrading the connection; right now all I/O is SSL/TLS, not IMAP */
+  if(imapc->state == IMAP_UPGRADETLS)
+    return imap_perform_upgrade_tls(conn);
+
+  /* Flush any data that needs to be sent */
+  if(pp->sendleft)
+    return Curl_pp_flushsend(pp);
+
+  do {
+    /* Read the response from the server */
+    result = Curl_pp_readresp(sock, pp, &imapcode, &nread);
+    if(result)
+      return result;
+
+    /* Was there an error parsing the response line? */
+    if(imapcode == -1)
+      return CURLE_WEIRD_SERVER_REPLY;
+
+    if(!imapcode)
+      break;
+
+    /* We have now received a full IMAP server response */
+    switch(imapc->state) {
+    case IMAP_SERVERGREET:
+      result = imap_state_servergreet_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_CAPABILITY:
+      result = imap_state_capability_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_STARTTLS:
+      result = imap_state_starttls_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_AUTHENTICATE:
+      result = imap_state_auth_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_LOGIN:
+      result = imap_state_login_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_LIST:
+      result = imap_state_listsearch_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_SELECT:
+      result = imap_state_select_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_FETCH:
+      result = imap_state_fetch_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_FETCH_FINAL:
+      result = imap_state_fetch_final_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_APPEND:
+      result = imap_state_append_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_APPEND_FINAL:
+      result = imap_state_append_final_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_SEARCH:
+      result = imap_state_listsearch_resp(conn, imapcode, imapc->state);
+      break;
+
+    case IMAP_LOGOUT:
+      /* fallthrough, just stop! */
+    default:
+      /* internal error */
+      state(conn, IMAP_STOP);
+      break;
+    }
+  } while(!result && imapc->state != IMAP_STOP && Curl_pp_moredata(pp));
+
+  return result;
+}
+
+/* Called repeatedly until done from multi.c */
+static CURLcode imap_multi_statemach(struct connectdata *conn, bool *done)
+{
+  CURLcode result = CURLE_OK;
+  struct imap_conn *imapc = &conn->proto.imapc;
+
+  if((conn->handler->flags & PROTOPT_SSL) && !imapc->ssldone) {
+    result = Curl_ssl_connect_nonblocking(conn, FIRSTSOCKET, &imapc->ssldone);
+    if(result || !imapc->ssldone)
+      return result;
+  }
+
+  result = Curl_pp_statemach(&imapc->pp, FALSE, FALSE);
+  *done = (imapc->state == IMAP_STOP) ? TRUE : FALSE;
+
+  return result;
+}
+
+static CURLcode imap_block_statemach(struct connectdata *conn,
+                                     bool disconnecting)
+{
+  CURLcode result = CURLE_OK;
+  struct imap_conn *imapc = &conn->proto.imapc;
+
+  while(imapc->state != IMAP_STOP && !result)
+    result = Curl_pp_statemach(&imapc->pp, TRUE, disconnecting);
+
+  return result;
+}
+
+/* Allocate and initialize the struct IMAP for the current Curl_easy if
+   required */
+static CURLcode imap_init(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct IMAP *imap;
+
+  imap = data->req.protop = calloc(sizeof(struct IMAP), 1);
+  if(!imap)
+    result = CURLE_OUT_OF_MEMORY;
+
+  return result;
+}
+
+/* For the IMAP "protocol connect" and "doing" phases only */
+static int imap_getsock(struct connectdata *conn, curl_socket_t *socks)
+{
+  return Curl_pp_getsock(&conn->proto.imapc.pp, socks);
+}
+
+/***********************************************************************
+ *
+ * imap_connect()
+ *
+ * This function should do everything that is to be considered a part of the
+ * connection phase.
+ *
+ * The variable 'done' points to will be TRUE if the protocol-layer connect
+ * phase is done when this function returns, or FALSE if not.
+ */
+static CURLcode imap_connect(struct connectdata *conn, bool *done)
+{
+  CURLcode result = CURLE_OK;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  struct pingpong *pp = &imapc->pp;
+
+  *done = FALSE; /* default to not done yet */
+
+  /* We always support persistent connections in IMAP */
+  connkeep(conn, "IMAP default");
+
+  /* Set the default response time-out */
+  pp->response_time = RESP_TIMEOUT;
+  pp->statemach_act = imap_statemach_act;
+  pp->endofresp = imap_endofresp;
+  pp->conn = conn;
+
+  /* Set the default preferred authentication type and mechanism */
+  imapc->preftype = IMAP_TYPE_ANY;
+  Curl_sasl_init(&imapc->sasl, &saslimap);
+
+  /* Initialise the pingpong layer */
+  Curl_pp_init(pp);
+
+  /* Parse the URL options */
+  result = imap_parse_url_options(conn);
+  if(result)
+    return result;
+
+  /* Start off waiting for the server greeting response */
+  state(conn, IMAP_SERVERGREET);
+
+  /* Start off with an response id of '*' */
+  strcpy(imapc->resptag, "*");
+
+  result = imap_multi_statemach(conn, done);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_done()
+ *
+ * The DONE function. This does what needs to be done after a single DO has
+ * performed.
+ *
+ * Input argument is already checked for validity.
+ */
+static CURLcode imap_done(struct connectdata *conn, CURLcode status,
+                          bool premature)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct IMAP *imap = data->req.protop;
+
+  (void)premature;
+
+  if(!imap)
+    return CURLE_OK;
+
+  if(status) {
+    connclose(conn, "IMAP done with bad status"); /* marked for closure */
+    result = status;         /* use the already set error code */
+  }
+  else if(!data->set.connect_only && !imap->custom &&
+          (imap->uid || imap->mindex || data->set.upload ||
+          data->set.mimepost.kind != MIMEKIND_NONE)) {
+    /* Handle responses after FETCH or APPEND transfer has finished */
+
+    if(!data->set.upload && data->set.mimepost.kind == MIMEKIND_NONE)
+      state(conn, IMAP_FETCH_FINAL);
+    else {
+      /* End the APPEND command first by sending an empty line */
+      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", "");
+      if(!result)
+        state(conn, IMAP_APPEND_FINAL);
+    }
+
+    /* Run the state-machine */
+    if(!result)
+      result = imap_block_statemach(conn, FALSE);
+  }
+
+  /* Cleanup our per-request based variables */
+  Curl_safefree(imap->mailbox);
+  Curl_safefree(imap->uidvalidity);
+  Curl_safefree(imap->uid);
+  Curl_safefree(imap->mindex);
+  Curl_safefree(imap->section);
+  Curl_safefree(imap->partial);
+  Curl_safefree(imap->query);
+  Curl_safefree(imap->custom);
+  Curl_safefree(imap->custom_params);
+
+  /* Clear the transfer mode for the next request */
+  imap->transfer = FTPTRANSFER_BODY;
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_perform()
+ *
+ * This is the actual DO function for IMAP. Fetch or append a message, or do
+ * other things according to the options previously setup.
+ */
+static CURLcode imap_perform(struct connectdata *conn, bool *connected,
+                             bool *dophase_done)
+{
+  /* This is IMAP and no proxy */
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct IMAP *imap = data->req.protop;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  bool selected = FALSE;
+
+  DEBUGF(infof(conn->data, "DO phase starts\n"));
+
+  if(conn->data->set.opt_no_body) {
+    /* Requested no body means no transfer */
+    imap->transfer = FTPTRANSFER_INFO;
+  }
+
+  *dophase_done = FALSE; /* not done yet */
+
+  /* Determine if the requested mailbox (with the same UIDVALIDITY if set)
+     has already been selected on this connection */
+  if(imap->mailbox && imapc->mailbox &&
+     strcasecompare(imap->mailbox, imapc->mailbox) &&
+     (!imap->uidvalidity || !imapc->mailbox_uidvalidity ||
+      strcasecompare(imap->uidvalidity, imapc->mailbox_uidvalidity)))
+    selected = TRUE;
+
+  /* Start the first command in the DO phase */
+  if(conn->data->set.upload || data->set.mimepost.kind != MIMEKIND_NONE)
+    /* APPEND can be executed directly */
+    result = imap_perform_append(conn);
+  else if(imap->custom && (selected || !imap->mailbox))
+    /* Custom command using the same mailbox or no mailbox */
+    result = imap_perform_list(conn);
+  else if(!imap->custom && selected && (imap->uid || imap->mindex))
+    /* FETCH from the same mailbox */
+    result = imap_perform_fetch(conn);
+  else if(!imap->custom && selected && imap->query)
+    /* SEARCH the current mailbox */
+    result = imap_perform_search(conn);
+  else if(imap->mailbox && !selected &&
+         (imap->custom || imap->uid || imap->mindex || imap->query))
+    /* SELECT the mailbox */
+    result = imap_perform_select(conn);
+  else
+    /* LIST */
+    result = imap_perform_list(conn);
+
+  if(result)
+    return result;
+
+  /* Run the state-machine */
+  result = imap_multi_statemach(conn, dophase_done);
+
+  *connected = conn->bits.tcpconnect[FIRSTSOCKET];
+
+  if(*dophase_done)
+    DEBUGF(infof(conn->data, "DO phase is complete\n"));
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_do()
+ *
+ * This function is registered as 'curl_do' function. It decodes the path
+ * parts etc as a wrapper to the actual DO function (imap_perform).
+ *
+ * The input argument is already checked for validity.
+ */
+static CURLcode imap_do(struct connectdata *conn, bool *done)
+{
+  CURLcode result = CURLE_OK;
+
+  *done = FALSE; /* default to false */
+
+  /* Parse the URL path */
+  result = imap_parse_url_path(conn);
+  if(result)
+    return result;
+
+  /* Parse the custom request */
+  result = imap_parse_custom_request(conn);
+  if(result)
+    return result;
+
+  result = imap_regular_transfer(conn, done);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_disconnect()
+ *
+ * Disconnect from an IMAP server. Cleanup protocol-specific per-connection
+ * resources. BLOCKING.
+ */
+static CURLcode imap_disconnect(struct connectdata *conn, bool dead_connection)
+{
+  struct imap_conn *imapc = &conn->proto.imapc;
+
+  /* We cannot send quit unconditionally. If this connection is stale or
+     bad in any way, sending quit and waiting around here will make the
+     disconnect wait in vain and cause more problems than we need to. */
+
+  /* The IMAP session may or may not have been allocated/setup at this
+     point! */
+  if(!dead_connection && imapc->pp.conn && imapc->pp.conn->bits.protoconnstart)
+    if(!imap_perform_logout(conn))
+      (void)imap_block_statemach(conn, TRUE); /* ignore errors on LOGOUT */
+
+  /* Disconnect from the server */
+  Curl_pp_disconnect(&imapc->pp);
+
+  /* Cleanup the SASL module */
+  Curl_sasl_cleanup(conn, imapc->sasl.authused);
+
+  /* Cleanup our connection based variables */
+  Curl_safefree(imapc->mailbox);
+  Curl_safefree(imapc->mailbox_uidvalidity);
+
+  return CURLE_OK;
+}
+
+/* Call this when the DO phase has completed */
+static CURLcode imap_dophase_done(struct connectdata *conn, bool connected)
+{
+  struct IMAP *imap = conn->data->req.protop;
+
+  (void)connected;
+
+  if(imap->transfer != FTPTRANSFER_BODY)
+    /* no data to transfer */
+    Curl_setup_transfer(conn->data, -1, -1, FALSE, -1);
+
+  return CURLE_OK;
+}
+
+/* Called from multi.c while DOing */
+static CURLcode imap_doing(struct connectdata *conn, bool *dophase_done)
+{
+  CURLcode result = imap_multi_statemach(conn, dophase_done);
+
+  if(result)
+    DEBUGF(infof(conn->data, "DO phase failed\n"));
+  else if(*dophase_done) {
+    result = imap_dophase_done(conn, FALSE /* not connected */);
+
+    DEBUGF(infof(conn->data, "DO phase is complete\n"));
+  }
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_regular_transfer()
+ *
+ * The input argument is already checked for validity.
+ *
+ * Performs all commands done before a regular transfer between a local and a
+ * remote host.
+ */
+static CURLcode imap_regular_transfer(struct connectdata *conn,
+                                      bool *dophase_done)
+{
+  CURLcode result = CURLE_OK;
+  bool connected = FALSE;
+  struct Curl_easy *data = conn->data;
+
+  /* Make sure size is unknown at this point */
+  data->req.size = -1;
+
+  /* Set the progress data */
+  Curl_pgrsSetUploadCounter(data, 0);
+  Curl_pgrsSetDownloadCounter(data, 0);
+  Curl_pgrsSetUploadSize(data, -1);
+  Curl_pgrsSetDownloadSize(data, -1);
+
+  /* Carry out the perform */
+  result = imap_perform(conn, &connected, dophase_done);
+
+  /* Perform post DO phase operations if necessary */
+  if(!result && *dophase_done)
+    result = imap_dophase_done(conn, connected);
+
+  return result;
+}
+
+static CURLcode imap_setup_connection(struct connectdata *conn)
+{
+  /* Initialise the IMAP layer */
+  CURLcode result = imap_init(conn);
+  if(result)
+    return result;
+
+  /* Clear the TLS upgraded flag */
+  conn->tls_upgraded = FALSE;
+
+  return CURLE_OK;
+}
+
+/***********************************************************************
+ *
+ * imap_sendf()
+ *
+ * Sends the formatted string as an IMAP command to the server.
+ *
+ * Designed to never block.
+ */
+static CURLcode imap_sendf(struct connectdata *conn, const char *fmt, ...)
+{
+  CURLcode result = CURLE_OK;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  char *taggedfmt;
+  va_list ap;
+
+  DEBUGASSERT(fmt);
+
+  /* Calculate the next command ID wrapping at 3 digits */
+  imapc->cmdid = (imapc->cmdid + 1) % 1000;
+
+  /* Calculate the tag based on the connection ID and command ID */
+  msnprintf(imapc->resptag, sizeof(imapc->resptag), "%c%03d",
+            'A' + curlx_sltosi(conn->connection_id % 26), imapc->cmdid);
+
+  /* Prefix the format with the tag */
+  taggedfmt = aprintf("%s %s", imapc->resptag, fmt);
+  if(!taggedfmt)
+    return CURLE_OUT_OF_MEMORY;
+
+  /* Send the data with the tag */
+  va_start(ap, fmt);
+  result = Curl_pp_vsendf(&imapc->pp, taggedfmt, ap);
+  va_end(ap);
+
+  free(taggedfmt);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_atom()
+ *
+ * Checks the input string for characters that need escaping and returns an
+ * atom ready for sending to the server.
+ *
+ * The returned string needs to be freed.
+ *
+ */
+static char *imap_atom(const char *str, bool escape_only)
+{
+  /* !checksrc! disable PARENBRACE 1 */
+  const char atom_specials[] = "(){ %*]";
+  const char *p1;
+  char *p2;
+  size_t backsp_count = 0;
+  size_t quote_count = 0;
+  bool others_exists = FALSE;
+  size_t newlen = 0;
+  char *newstr = NULL;
+
+  if(!str)
+    return NULL;
+
+  /* Look for "atom-specials", counting the backslash and quote characters as
+     these will need escaping */
+  p1 = str;
+  while(*p1) {
+    if(*p1 == '\\')
+      backsp_count++;
+    else if(*p1 == '"')
+      quote_count++;
+    else if(!escape_only) {
+      const char *p3 = atom_specials;
+
+      while(*p3 && !others_exists) {
+        if(*p1 == *p3)
+          others_exists = TRUE;
+
+        p3++;
+      }
+    }
+
+    p1++;
+  }
+
+  /* Does the input contain any "atom-special" characters? */
+  if(!backsp_count && !quote_count && !others_exists)
+    return strdup(str);
+
+  /* Calculate the new string length */
+  newlen = strlen(str) + backsp_count + quote_count + (escape_only ? 0 : 2);
+
+  /* Allocate the new string */
+  newstr = (char *) malloc((newlen + 1) * sizeof(char));
+  if(!newstr)
+    return NULL;
+
+  /* Surround the string in quotes if necessary */
+  p2 = newstr;
+  if(!escape_only) {
+    newstr[0] = '"';
+    newstr[newlen - 1] = '"';
+    p2++;
+  }
+
+  /* Copy the string, escaping backslash and quote characters along the way */
+  p1 = str;
+  while(*p1) {
+    if(*p1 == '\\' || *p1 == '"') {
+      *p2 = '\\';
+      p2++;
+    }
+
+   *p2 = *p1;
+
+    p1++;
+    p2++;
+  }
+
+  /* Terminate the string */
+  newstr[newlen] = '\0';
+
+  return newstr;
+}
+
+/***********************************************************************
+ *
+ * imap_is_bchar()
+ *
+ * Portable test of whether the specified char is a "bchar" as defined in the
+ * grammar of RFC-5092.
+ */
+static bool imap_is_bchar(char ch)
+{
+  switch(ch) {
+    /* bchar */
+    case ':': case '@': case '/':
+    /* bchar -> achar */
+    case '&': case '=':
+    /* bchar -> achar -> uchar -> unreserved */
+    case '0': case '1': case '2': case '3': case '4': case '5': case '6':
+    case '7': case '8': case '9':
+    case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': case 'G':
+    case 'H': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N':
+    case 'O': case 'P': case 'Q': case 'R': case 'S': case 'T': case 'U':
+    case 'V': case 'W': case 'X': case 'Y': case 'Z':
+    case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g':
+    case 'h': case 'i': case 'j': case 'k': case 'l': case 'm': case 'n':
+    case 'o': case 'p': case 'q': case 'r': case 's': case 't': case 'u':
+    case 'v': case 'w': case 'x': case 'y': case 'z':
+    case '-': case '.': case '_': case '~':
+    /* bchar -> achar -> uchar -> sub-delims-sh */
+    case '!': case '$': case '\'': case '(': case ')': case '*':
+    case '+': case ',':
+    /* bchar -> achar -> uchar -> pct-encoded */
+    case '%': /* HEXDIG chars are already included above */
+      return true;
+
+    default:
+      return false;
+  }
+}
+
+/***********************************************************************
+ *
+ * imap_parse_url_options()
+ *
+ * Parse the URL login options.
+ */
+static CURLcode imap_parse_url_options(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct imap_conn *imapc = &conn->proto.imapc;
+  const char *ptr = conn->options;
+
+  imapc->sasl.resetprefs = TRUE;
+
+  while(!result && ptr && *ptr) {
+    const char *key = ptr;
+    const char *value;
+
+    while(*ptr && *ptr != '=')
+        ptr++;
+
+    value = ptr + 1;
+
+    while(*ptr && *ptr != ';')
+      ptr++;
+
+    if(strncasecompare(key, "AUTH=", 5))
+      result = Curl_sasl_parse_url_auth_option(&imapc->sasl,
+                                               value, ptr - value);
+    else
+      result = CURLE_URL_MALFORMAT;
+
+    if(*ptr == ';')
+      ptr++;
+  }
+
+  switch(imapc->sasl.prefmech) {
+  case SASL_AUTH_NONE:
+    imapc->preftype = IMAP_TYPE_NONE;
+    break;
+  case SASL_AUTH_DEFAULT:
+    imapc->preftype = IMAP_TYPE_ANY;
+    break;
+  default:
+    imapc->preftype = IMAP_TYPE_SASL;
+    break;
+  }
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * imap_parse_url_path()
+ *
+ * Parse the URL path into separate path components.
+ *
+ */
+static CURLcode imap_parse_url_path(struct connectdata *conn)
+{
+  /* The imap struct is already initialised in imap_connect() */
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct IMAP *imap = data->req.protop;
+  const char *begin = &data->state.up.path[1]; /* skip leading slash */
+  const char *ptr = begin;
+
+  /* See how much of the URL is a valid path and decode it */
+  while(imap_is_bchar(*ptr))
+    ptr++;
+
+  if(ptr != begin) {
+    /* Remove the trailing slash if present */
+    const char *end = ptr;
+    if(end > begin && end[-1] == '/')
+      end--;
+
+    result = Curl_urldecode(data, begin, end - begin, &imap->mailbox, NULL,
+                            TRUE);
+    if(result)
+      return result;
+  }
+  else
+    imap->mailbox = NULL;
+
+  /* There can be any number of parameters in the form ";NAME=VALUE" */
+  while(*ptr == ';') {
+    char *name;
+    char *value;
+    size_t valuelen;
+
+    /* Find the length of the name parameter */
+    begin = ++ptr;
+    while(*ptr && *ptr != '=')
+      ptr++;
+
+    if(!*ptr)
+      return CURLE_URL_MALFORMAT;
+
+    /* Decode the name parameter */
+    result = Curl_urldecode(data, begin, ptr - begin, &name, NULL, TRUE);
+    if(result)
+      return result;
+
+    /* Find the length of the value parameter */
+    begin = ++ptr;
+    while(imap_is_bchar(*ptr))
+      ptr++;
+
+    /* Decode the value parameter */
+    result = Curl_urldecode(data, begin, ptr - begin, &value, &valuelen, TRUE);
+    if(result) {
+      free(name);
+      return result;
+    }
+
+    DEBUGF(infof(conn->data, "IMAP URL parameter '%s' = '%s'\n", name, value));
+
+    /* Process the known hierarchical parameters (UIDVALIDITY, UID, SECTION and
+       PARTIAL) stripping of the trailing slash character if it is present.
+
+       Note: Unknown parameters trigger a URL_MALFORMAT error. */
+    if(strcasecompare(name, "UIDVALIDITY") && !imap->uidvalidity) {
+      if(valuelen > 0 && value[valuelen - 1] == '/')
+        value[valuelen - 1] = '\0';
+
+      imap->uidvalidity = value;
+      value = NULL;
+    }
+    else if(strcasecompare(name, "UID") && !imap->uid) {
+      if(valuelen > 0 && value[valuelen - 1] == '/')
+        value[valuelen - 1] = '\0';
+
+      imap->uid = value;
+      value = NULL;
+    }
+    else if(strcasecompare(name, "MAILINDEX") && !imap->mindex) {
+      if(valuelen > 0 && value[valuelen - 1] == '/')
+        value[valuelen - 1] = '\0';
+
+      imap->mindex = value;
+      value = NULL;
+    }
+    else if(strcasecompare(name, "SECTION") && !imap->section) {
+      if(valuelen > 0 && value[valuelen - 1] == '/')
+        value[valuelen - 1] = '\0';
+
+      imap->section = value;
+      value = NULL;
+    }
+    else if(strcasecompare(name, "PARTIAL") && !imap->partial) {
+      if(valuelen > 0 && value[valuelen - 1] == '/')
+        value[valuelen - 1] = '\0';
+
+      imap->partial = value;
+      value = NULL;
+    }
+    else {
+      free(name);
+      free(value);
+
+      return CURLE_URL_MALFORMAT;
+    }
+
+    free(name);
+    free(value);
+  }
+
+  /* Does the URL contain a query parameter? Only valid when we have a mailbox
+     and no UID as per RFC-5092 */
+  if(imap->mailbox && !imap->uid && !imap->mindex) {
+    /* Get the query parameter, URL decoded */
+    (void)curl_url_get(data->state.uh, CURLUPART_QUERY, &imap->query,
+                       CURLU_URLDECODE);
+  }
+
+  /* Any extra stuff at the end of the URL is an error */
+  if(*ptr)
+    return CURLE_URL_MALFORMAT;
+
+  return CURLE_OK;
+}
+
+/***********************************************************************
+ *
+ * imap_parse_custom_request()
+ *
+ * Parse the custom request.
+ */
+static CURLcode imap_parse_custom_request(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct Curl_easy *data = conn->data;
+  struct IMAP *imap = data->req.protop;
+  const char *custom = data->set.str[STRING_CUSTOMREQUEST];
+
+  if(custom) {
+    /* URL decode the custom request */
+    result = Curl_urldecode(data, custom, 0, &imap->custom, NULL, TRUE);
+
+    /* Extract the parameters if specified */
+    if(!result) {
+      const char *params = imap->custom;
+
+      while(*params && *params != ' ')
+        params++;
+
+      if(*params) {
+        imap->custom_params = strdup(params);
+        imap->custom[params - imap->custom] = '\0';
+
+        if(!imap->custom_params)
+          result = CURLE_OUT_OF_MEMORY;
+      }
+    }
+  }
+
+  return result;
+}
+
+#endif /* CURL_DISABLE_IMAP */