libcurl extracted to the separate lib

git-svn-id: http://svn.miranda-ng.org/main/trunk@14683 1316c22d-e87f-b044-9b9b-93d7a3e3ba9c

1 files changed, 1996 insertions, 0 deletions

diff --git a/libs/libcurl/src/pop3.c b/libs/libcurl/src/pop3.c
new file mode 100644
index 0000000000..a771933840
--- /dev/null
+++ b/libs/libcurl/src/pop3.c
@@ -0,0 +1,1996 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2013, 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 http://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.
+ *
+ * RFC1734 POP3 Authentication
+ * RFC1939 POP3 protocol
+ * RFC2195 CRAM-MD5 authentication
+ * RFC2384 POP URL Scheme
+ * RFC2449 POP3 Extension Mechanism
+ * RFC2595 Using TLS with IMAP, POP3 and ACAP
+ * RFC2831 DIGEST-MD5 authentication
+ * RFC4422 Simple Authentication and Security Layer (SASL)
+ * RFC4616 PLAIN authentication
+ * RFC5034 POP3 SASL Authentication Mechanism
+ * RFC6749 OAuth 2.0 Authorization Framework
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#ifndef CURL_DISABLE_POP3
+
+#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 "if2ip.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 "pop3.h"
+
+#include "strtoofft.h"
+#include "strequal.h"
+#include "sslgen.h"
+#include "connect.h"
+#include "strerror.h"
+#include "select.h"
+#include "multiif.h"
+#include "url.h"
+#include "rawstr.h"
+#include "curl_sasl.h"
+#include "curl_md5.h"
+#include "warnless.h"
+
+#define _MPRINTF_REPLACE /* use our functions only */
+#include <curl/mprintf.h>
+
+#include "curl_memory.h"
+/* The last #include file should be: */
+#include "memdebug.h"
+
+/* Local API functions */
+static CURLcode pop3_regular_transfer(struct connectdata *conn, bool *done);
+static CURLcode pop3_do(struct connectdata *conn, bool *done);
+static CURLcode pop3_done(struct connectdata *conn, CURLcode status,
+                          bool premature);
+static CURLcode pop3_connect(struct connectdata *conn, bool *done);
+static CURLcode pop3_disconnect(struct connectdata *conn, bool dead);
+static CURLcode pop3_multi_statemach(struct connectdata *conn, bool *done);
+static int pop3_getsock(struct connectdata *conn, curl_socket_t *socks,
+                        int numsocks);
+static CURLcode pop3_doing(struct connectdata *conn, bool *dophase_done);
+static CURLcode pop3_setup_connection(struct connectdata *conn);
+static CURLcode pop3_parse_url_options(struct connectdata *conn);
+static CURLcode pop3_parse_url_path(struct connectdata *conn);
+static CURLcode pop3_parse_custom_request(struct connectdata *conn);
+
+/*
+ * POP3 protocol handler.
+ */
+
+const struct Curl_handler Curl_handler_pop3 = {
+  "POP3",                           /* scheme */
+  pop3_setup_connection,            /* setup_connection */
+  pop3_do,                          /* do_it */
+  pop3_done,                        /* done */
+  ZERO_NULL,                        /* do_more */
+  pop3_connect,                     /* connect_it */
+  pop3_multi_statemach,             /* connecting */
+  pop3_doing,                       /* doing */
+  pop3_getsock,                     /* proto_getsock */
+  pop3_getsock,                     /* doing_getsock */
+  ZERO_NULL,                        /* domore_getsock */
+  ZERO_NULL,                        /* perform_getsock */
+  pop3_disconnect,                  /* disconnect */
+  ZERO_NULL,                        /* readwrite */
+  PORT_POP3,                        /* defport */
+  CURLPROTO_POP3,                   /* protocol */
+  PROTOPT_CLOSEACTION | PROTOPT_NOURLQUERY /* flags */
+};
+
+#ifdef USE_SSL
+/*
+ * POP3S protocol handler.
+ */
+
+const struct Curl_handler Curl_handler_pop3s = {
+  "POP3S",                          /* scheme */
+  pop3_setup_connection,            /* setup_connection */
+  pop3_do,                          /* do_it */
+  pop3_done,                        /* done */
+  ZERO_NULL,                        /* do_more */
+  pop3_connect,                     /* connect_it */
+  pop3_multi_statemach,             /* connecting */
+  pop3_doing,                       /* doing */
+  pop3_getsock,                     /* proto_getsock */
+  pop3_getsock,                     /* doing_getsock */
+  ZERO_NULL,                        /* domore_getsock */
+  ZERO_NULL,                        /* perform_getsock */
+  pop3_disconnect,                  /* disconnect */
+  ZERO_NULL,                        /* readwrite */
+  PORT_POP3S,                       /* defport */
+  CURLPROTO_POP3 | CURLPROTO_POP3S, /* protocol */
+  PROTOPT_CLOSEACTION | PROTOPT_SSL
+  | PROTOPT_NOURLQUERY              /* flags */
+};
+#endif
+
+#ifndef CURL_DISABLE_HTTP
+/*
+ * HTTP-proxyed POP3 protocol handler.
+ */
+
+static const struct Curl_handler Curl_handler_pop3_proxy = {
+  "POP3",                               /* scheme */
+  Curl_http_setup_conn,                 /* setup_connection */
+  Curl_http,                            /* do_it */
+  Curl_http_done,                       /* done */
+  ZERO_NULL,                            /* do_more */
+  ZERO_NULL,                            /* connect_it */
+  ZERO_NULL,                            /* connecting */
+  ZERO_NULL,                            /* doing */
+  ZERO_NULL,                            /* proto_getsock */
+  ZERO_NULL,                            /* doing_getsock */
+  ZERO_NULL,                            /* domore_getsock */
+  ZERO_NULL,                            /* perform_getsock */
+  ZERO_NULL,                            /* disconnect */
+  ZERO_NULL,                            /* readwrite */
+  PORT_POP3,                            /* defport */
+  CURLPROTO_HTTP,                       /* protocol */
+  PROTOPT_NONE                          /* flags */
+};
+
+#ifdef USE_SSL
+/*
+ * HTTP-proxyed POP3S protocol handler.
+ */
+
+static const struct Curl_handler Curl_handler_pop3s_proxy = {
+  "POP3S",                              /* scheme */
+  Curl_http_setup_conn,                 /* setup_connection */
+  Curl_http,                            /* do_it */
+  Curl_http_done,                       /* done */
+  ZERO_NULL,                            /* do_more */
+  ZERO_NULL,                            /* connect_it */
+  ZERO_NULL,                            /* connecting */
+  ZERO_NULL,                            /* doing */
+  ZERO_NULL,                            /* proto_getsock */
+  ZERO_NULL,                            /* doing_getsock */
+  ZERO_NULL,                            /* domore_getsock */
+  ZERO_NULL,                            /* perform_getsock */
+  ZERO_NULL,                            /* disconnect */
+  ZERO_NULL,                            /* readwrite */
+  PORT_POP3S,                           /* defport */
+  CURLPROTO_HTTP,                       /* protocol */
+  PROTOPT_NONE                          /* flags */
+};
+#endif
+#endif
+
+#ifdef USE_SSL
+static void pop3_to_pop3s(struct connectdata *conn)
+{
+  conn->handler = &Curl_handler_pop3s;
+}
+#else
+#define pop3_to_pop3s(x) Curl_nop_stmt
+#endif
+
+/***********************************************************************
+ *
+ * pop3_endofresp()
+ *
+ * Checks for an ending POP3 status code at the start of the given string, but
+ * also detects the APOP timestamp from the server greeting and various
+ * capabilities from the CAPA response including the supported authentication
+ * types and allowed SASL mechanisms.
+ */
+static bool pop3_endofresp(struct connectdata *conn, char *line, size_t len,
+                           int *resp)
+{
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+  size_t wordlen;
+  size_t i;
+
+  /* Do we have an error response? */
+  if(len >= 4 && !memcmp("-ERR", line, 4)) {
+    *resp = '-';
+
+    return TRUE;
+  }
+
+  /* Are we processing servergreet responses? */
+  if(pop3c->state == POP3_SERVERGREET) {
+    /* Look for the APOP timestamp */
+    if(len >= 3 && line[len - 3] == '>') {
+      for(i = 0; i < len - 3; ++i) {
+        if(line[i] == '<') {
+          /* Calculate the length of the timestamp */
+          size_t timestamplen = len - 2 - i;
+
+          /* Allocate some memory for the timestamp */
+          pop3c->apoptimestamp = (char *)calloc(1, timestamplen + 1);
+
+          if(!pop3c->apoptimestamp)
+            break;
+
+          /* Copy the timestamp */
+          memcpy(pop3c->apoptimestamp, line + i, timestamplen);
+          pop3c->apoptimestamp[timestamplen] = '\0';
+          break;
+        }
+      }
+    }
+  }
+  /* Are we processing CAPA command responses? */
+  else if(pop3c->state == POP3_CAPA) {
+    /* Do we have the terminating line? */
+    if(len >= 1 && !memcmp(line, ".", 1)) {
+      *resp = '+';
+
+      return TRUE;
+    }
+
+    /* Does the server support the STLS capability? */
+    if(len >= 4 && !memcmp(line, "STLS", 4))
+      pop3c->tls_supported = TRUE;
+
+    /* Does the server support clear text authentication? */
+    else if(len >= 4 && !memcmp(line, "USER", 4))
+      pop3c->authtypes |= POP3_TYPE_CLEARTEXT;
+
+    /* Does the server support APOP authentication? */
+    else if(len >= 4 && !memcmp(line, "APOP", 4))
+      pop3c->authtypes |= POP3_TYPE_APOP;
+
+    /* Does the server support SASL based authentication? */
+    else if(len >= 5 && !memcmp(line, "SASL ", 5)) {
+      pop3c->authtypes |= POP3_TYPE_SASL;
+
+      /* Advance past the SASL keyword */
+      line += 5;
+      len -= 5;
+
+      /* Loop through the data line */
+      for(;;) {
+        while(len &&
+              (*line == ' ' || *line == '\t' ||
+               *line == '\r' || *line == '\n')) {
+
+          line++;
+          len--;
+        }
+
+        if(!len)
+          break;
+
+        /* Extract the word */
+        for(wordlen = 0; wordlen < len && line[wordlen] != ' ' &&
+              line[wordlen] != '\t' && line[wordlen] != '\r' &&
+              line[wordlen] != '\n';)
+          wordlen++;
+
+        /* Test the word for a matching authentication mechanism */
+        if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_LOGIN))
+          pop3c->authmechs |= SASL_MECH_LOGIN;
+        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_PLAIN))
+          pop3c->authmechs |= SASL_MECH_PLAIN;
+        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_CRAM_MD5))
+          pop3c->authmechs |= SASL_MECH_CRAM_MD5;
+        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_DIGEST_MD5))
+          pop3c->authmechs |= SASL_MECH_DIGEST_MD5;
+        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_GSSAPI))
+          pop3c->authmechs |= SASL_MECH_GSSAPI;
+        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_EXTERNAL))
+          pop3c->authmechs |= SASL_MECH_EXTERNAL;
+        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_NTLM))
+          pop3c->authmechs |= SASL_MECH_NTLM;
+        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_XOAUTH2))
+          pop3c->authmechs |= SASL_MECH_XOAUTH2;
+
+        line += wordlen;
+        len -= wordlen;
+      }
+    }
+
+    return FALSE;
+  }
+
+  /* Do we have a command or continuation response? */
+  if((len >= 3 && !memcmp("+OK", line, 3)) ||
+     (len >= 1 && !memcmp("+", line, 1))) {
+    *resp = '+';
+
+    return TRUE;
+  }
+
+  return FALSE; /* Nothing for us */
+}
+
+/***********************************************************************
+ *
+ * state()
+ *
+ * This is the ONLY way to change POP3 state!
+ */
+static void state(struct connectdata *conn, pop3state newstate)
+{
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
+  /* for debug purposes */
+  static const char * const names[] = {
+    "STOP",
+    "SERVERGREET",
+    "CAPA",
+    "STARTTLS",
+    "UPGRADETLS",
+    "AUTH_PLAIN",
+    "AUTH_LOGIN",
+    "AUTH_LOGIN_PASSWD",
+    "AUTH_CRAMMD5",
+    "AUTH_DIGESTMD5",
+    "AUTH_DIGESTMD5_RESP",
+    "AUTH_NTLM",
+    "AUTH_NTLM_TYPE2MSG",
+    "AUTH_XOAUTH2",
+    "AUTH_FINAL",
+    "APOP",
+    "USER",
+    "PASS",
+    "COMMAND",
+    "QUIT",
+    /* LAST */
+  };
+
+  if(pop3c->state != newstate)
+    infof(conn->data, "POP3 %p state change from %s to %s\n",
+          (void *)pop3c, names[pop3c->state], names[newstate]);
+#endif
+
+  pop3c->state = newstate;
+}
+
+/***********************************************************************
+ *
+ * pop3_perform_capa()
+ *
+ * Sends the CAPA command in order to obtain a list of server side supported
+ * capabilities.
+ */
+static CURLcode pop3_perform_capa(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+
+  pop3c->authmechs = 0;         /* No known authentication mechanisms yet */
+  pop3c->authused = 0;          /* Clear the authentication mechanism used */
+  pop3c->tls_supported = FALSE; /* Clear the TLS capability */
+
+  /* Send the CAPA command */
+  result = Curl_pp_sendf(&pop3c->pp, "%s", "CAPA");
+
+  if(!result)
+    state(conn, POP3_CAPA);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_perform_starttls()
+ *
+ * Sends the STLS command to start the upgrade to TLS.
+ */
+static CURLcode pop3_perform_starttls(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+
+  /* Send the STLS command */
+  result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", "STLS");
+
+  if(!result)
+    state(conn, POP3_STARTTLS);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_perform_upgrade_tls()
+ *
+ * Performs the upgrade to TLS.
+ */
+static CURLcode pop3_perform_upgrade_tls(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+
+  /* Start the SSL connection */
+  result = Curl_ssl_connect_nonblocking(conn, FIRSTSOCKET, &pop3c->ssldone);
+
+  if(!result) {
+    if(pop3c->state != POP3_UPGRADETLS)
+      state(conn, POP3_UPGRADETLS);
+
+    if(pop3c->ssldone) {
+      pop3_to_pop3s(conn);
+      result = pop3_perform_capa(conn);
+    }
+  }
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_perform_user()
+ *
+ * Sends a clear text USER command to authenticate with.
+ */
+static CURLcode pop3_perform_user(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+
+  /* 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, POP3_STOP);
+
+    return result;
+  }
+
+  /* Send the USER command */
+  result = Curl_pp_sendf(&conn->proto.pop3c.pp, "USER %s",
+                         conn->user ? conn->user : "");
+  if(!result)
+    state(conn, POP3_USER);
+
+  return result;
+}
+
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+/***********************************************************************
+ *
+ * pop3_perform_apop()
+ *
+ * Sends an APOP command to authenticate with.
+ */
+static CURLcode pop3_perform_apop(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+  size_t i;
+  MD5_context *ctxt;
+  unsigned char digest[MD5_DIGEST_LEN];
+  char secret[2 * MD5_DIGEST_LEN + 1];
+
+  /* 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, POP3_STOP);
+
+    return result;
+  }
+
+  /* Create the digest */
+  ctxt = Curl_MD5_init(Curl_DIGEST_MD5);
+  if(!ctxt)
+    return CURLE_OUT_OF_MEMORY;
+
+  Curl_MD5_update(ctxt, (const unsigned char *) pop3c->apoptimestamp,
+                  curlx_uztoui(strlen(pop3c->apoptimestamp)));
+
+  Curl_MD5_update(ctxt, (const unsigned char *) conn->passwd,
+                  curlx_uztoui(strlen(conn->passwd)));
+
+  /* Finalise the digest */
+  Curl_MD5_final(ctxt, digest);
+
+  /* Convert the calculated 16 octet digest into a 32 byte hex string */
+  for(i = 0; i < MD5_DIGEST_LEN; i++)
+    snprintf(&secret[2 * i], 3, "%02x", digest[i]);
+
+  result = Curl_pp_sendf(&pop3c->pp, "APOP %s %s", conn->user, secret);
+
+  if(!result)
+    state(conn, POP3_APOP);
+
+  return result;
+}
+#endif
+
+/***********************************************************************
+ *
+ * pop3_perform_authenticate()
+ *
+ * Sends an AUTH command allowing the client to login with the appropriate
+ * SASL authentication mechanism.
+ *
+ * Additionally, the function will perform fallback to APOP and USER commands
+ * should a common mechanism not be available between the client and server.
+ */
+static CURLcode pop3_perform_authenticate(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+  const char *mech = NULL;
+  char *initresp = NULL;
+  size_t len = 0;
+  pop3state state1 = POP3_STOP;
+  pop3state state2 = POP3_STOP;
+
+  /* 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, POP3_STOP);
+
+    return result;
+  }
+
+  /* Calculate the supported authentication mechanism by decreasing order of
+     security */
+  if(pop3c->authtypes & POP3_TYPE_SASL) {
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+    if((pop3c->authmechs & SASL_MECH_DIGEST_MD5) &&
+       (pop3c->prefmech & SASL_MECH_DIGEST_MD5)) {
+      mech = SASL_MECH_STRING_DIGEST_MD5;
+      state1 = POP3_AUTH_DIGESTMD5;
+      pop3c->authused = SASL_MECH_DIGEST_MD5;
+    }
+    else if((pop3c->authmechs & SASL_MECH_CRAM_MD5) &&
+            (pop3c->prefmech & SASL_MECH_CRAM_MD5)) {
+      mech = SASL_MECH_STRING_CRAM_MD5;
+      state1 = POP3_AUTH_CRAMMD5;
+      pop3c->authused = SASL_MECH_CRAM_MD5;
+    }
+    else
+#endif
+#ifdef USE_NTLM
+    if((pop3c->authmechs & SASL_MECH_NTLM) &&
+       (pop3c->prefmech & SASL_MECH_NTLM)) {
+      mech = SASL_MECH_STRING_NTLM;
+      state1 = POP3_AUTH_NTLM;
+      state2 = POP3_AUTH_NTLM_TYPE2MSG;
+      pop3c->authused = SASL_MECH_NTLM;
+
+      if(data->set.sasl_ir)
+        result = Curl_sasl_create_ntlm_type1_message(conn->user, conn->passwd,
+                                                     &conn->ntlm,
+                                                     &initresp, &len);
+    }
+    else
+#endif
+    if(((pop3c->authmechs & SASL_MECH_XOAUTH2) &&
+        (pop3c->prefmech & SASL_MECH_XOAUTH2) &&
+        (pop3c->prefmech != SASL_AUTH_ANY)) || conn->xoauth2_bearer) {
+      mech = SASL_MECH_STRING_XOAUTH2;
+      state1 = POP3_AUTH_XOAUTH2;
+      state2 = POP3_AUTH_FINAL;
+      pop3c->authused = SASL_MECH_XOAUTH2;
+
+      if(data->set.sasl_ir)
+        result = Curl_sasl_create_xoauth2_message(conn->data, conn->user,
+                                                  conn->xoauth2_bearer,
+                                                  &initresp, &len);
+    }
+    else if((pop3c->authmechs & SASL_MECH_LOGIN) &&
+       (pop3c->prefmech & SASL_MECH_LOGIN)) {
+      mech = SASL_MECH_STRING_LOGIN;
+      state1 = POP3_AUTH_LOGIN;
+      state2 = POP3_AUTH_LOGIN_PASSWD;
+      pop3c->authused = SASL_MECH_LOGIN;
+
+      if(data->set.sasl_ir)
+        result = Curl_sasl_create_login_message(conn->data, conn->user,
+                                                &initresp, &len);
+    }
+    else if((pop3c->authmechs & SASL_MECH_PLAIN) &&
+            (pop3c->prefmech & SASL_MECH_PLAIN)) {
+      mech = SASL_MECH_STRING_PLAIN;
+      state1 = POP3_AUTH_PLAIN;
+      state2 = POP3_AUTH_FINAL;
+      pop3c->authused = SASL_MECH_PLAIN;
+
+      if(data->set.sasl_ir)
+        result = Curl_sasl_create_plain_message(conn->data, conn->user,
+                                                conn->passwd, &initresp,
+                                                &len);
+    }
+  }
+
+  if(!result) {
+    if(mech && (pop3c->preftype & POP3_TYPE_SASL)) {
+      /* Perform SASL based authentication */
+      if(initresp &&
+         8 + strlen(mech) + len <= 255) { /* AUTH <mech> ...<crlf> */
+        result = Curl_pp_sendf(&pop3c->pp, "AUTH %s %s", mech, initresp);
+
+        if(!result)
+          state(conn, state2);
+      }
+      else {
+        result = Curl_pp_sendf(&pop3c->pp, "AUTH %s", mech);
+
+        if(!result)
+          state(conn, state1);
+      }
+
+      Curl_safefree(initresp);
+    }
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+    else if((pop3c->authtypes & POP3_TYPE_APOP) &&
+            (pop3c->preftype & POP3_TYPE_APOP))
+      /* Perform APOP authentication */
+      result = pop3_perform_apop(conn);
+#endif
+    else if((pop3c->authtypes & POP3_TYPE_CLEARTEXT) &&
+            (pop3c->preftype & POP3_TYPE_CLEARTEXT))
+      /* Perform clear text authentication */
+      result = pop3_perform_user(conn);
+    else {
+      /* Other mechanisms not supported */
+      infof(conn->data, "No known authentication mechanisms supported!\n");
+      result = CURLE_LOGIN_DENIED;
+    }
+  }
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_perform_command()
+ *
+ * Sends a POP3 based command.
+ */
+static CURLcode pop3_perform_command(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  struct POP3 *pop3 = data->req.protop;
+  const char *command = NULL;
+
+  /* Calculate the default command */
+  if(pop3->id[0] == '\0' || conn->data->set.ftp_list_only) {
+    command = "LIST";
+
+    if(pop3->id[0] != '\0')
+      /* Message specific LIST so skip the BODY transfer */
+      pop3->transfer = FTPTRANSFER_INFO;
+  }
+  else
+    command = "RETR";
+
+  /* Send the command */
+  if(pop3->id[0] != '\0')
+    result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s %s",
+                           (pop3->custom && pop3->custom[0] != '\0' ?
+                            pop3->custom : command), pop3->id);
+  else
+    result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s",
+                           (pop3->custom && pop3->custom[0] != '\0' ?
+                            pop3->custom : command));
+
+  if(!result)
+    state(conn, POP3_COMMAND);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_perform_quit()
+ *
+ * Performs the quit action prior to sclose() be called.
+ */
+static CURLcode pop3_perform_quit(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+
+  /* Send the QUIT command */
+  result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", "QUIT");
+
+  if(!result)
+    state(conn, POP3_QUIT);
+
+  return result;
+}
+
+/* For the initial server greeting */
+static CURLcode pop3_state_servergreet_resp(struct connectdata *conn,
+                                            int pop3code,
+                                            pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Got unexpected pop3-server response");
+    result = CURLE_FTP_WEIRD_SERVER_REPLY;
+  }
+  else
+    result = pop3_perform_capa(conn);
+
+  return result;
+}
+
+/* For CAPA responses */
+static CURLcode pop3_state_capa_resp(struct connectdata *conn, int pop3code,
+                                     pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+')
+    result = pop3_perform_user(conn);
+  else if(data->set.use_ssl && !conn->ssl[FIRSTSOCKET].use) {
+    /* We don't have a SSL/TLS connection yet, but SSL is requested */
+    if(pop3c->tls_supported)
+      /* Switch to TLS connection now */
+      result = pop3_perform_starttls(conn);
+    else if(data->set.use_ssl == CURLUSESSL_TRY)
+      /* Fallback and carry on with authentication */
+      result = pop3_perform_authenticate(conn);
+    else {
+      failf(data, "STLS not supported.");
+      result = CURLE_USE_SSL_FAILED;
+    }
+  }
+  else
+    result = pop3_perform_authenticate(conn);
+
+  return result;
+}
+
+/* For STARTTLS responses */
+static CURLcode pop3_state_starttls_resp(struct connectdata *conn,
+                                         int pop3code,
+                                         pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    if(data->set.use_ssl != CURLUSESSL_TRY) {
+      failf(data, "STARTTLS denied. %c", pop3code);
+      result = CURLE_USE_SSL_FAILED;
+    }
+    else
+      result = pop3_perform_authenticate(conn);
+  }
+  else
+    result = pop3_perform_upgrade_tls(conn);
+
+  return result;
+}
+
+/* For AUTH PLAIN (without initial response) responses */
+static CURLcode pop3_state_auth_plain_resp(struct connectdata *conn,
+                                           int pop3code,
+                                           pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  size_t len = 0;
+  char *plainauth = NULL;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied. %c", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else {
+    /* Create the authorisation message */
+    result = Curl_sasl_create_plain_message(data, conn->user, conn->passwd,
+                                            &plainauth, &len);
+
+    /* Send the message */
+    if(!result) {
+      if(plainauth) {
+        result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", plainauth);
+
+        if(!result)
+          state(conn, POP3_AUTH_FINAL);
+      }
+
+      Curl_safefree(plainauth);
+    }
+  }
+
+  return result;
+}
+
+/* For AUTH LOGIN (without initial response) responses */
+static CURLcode pop3_state_auth_login_resp(struct connectdata *conn,
+                                           int pop3code,
+                                           pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  size_t len = 0;
+  char *authuser = NULL;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied: %d", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else {
+    /* Create the user message */
+    result = Curl_sasl_create_login_message(data, conn->user,
+                                            &authuser, &len);
+
+    /* Send the user */
+    if(!result) {
+      if(authuser) {
+        result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", authuser);
+
+        if(!result)
+          state(conn, POP3_AUTH_LOGIN_PASSWD);
+      }
+
+      Curl_safefree(authuser);
+    }
+  }
+
+  return result;
+}
+
+/* For AUTH LOGIN user entry responses */
+static CURLcode pop3_state_auth_login_password_resp(struct connectdata *conn,
+                                                    int pop3code,
+                                                    pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  size_t len = 0;
+  char *authpasswd = NULL;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied: %d", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else {
+    /* Create the password message */
+    result = Curl_sasl_create_login_message(data, conn->passwd,
+                                            &authpasswd, &len);
+
+    /* Send the password */
+    if(!result) {
+      if(authpasswd) {
+        result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", authpasswd);
+
+        if(!result)
+          state(conn, POP3_AUTH_FINAL);
+      }
+
+      Curl_safefree(authpasswd);
+    }
+  }
+
+  return result;
+}
+
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+/* For AUTH CRAM-MD5 responses */
+static CURLcode pop3_state_auth_cram_resp(struct connectdata *conn,
+                                          int pop3code,
+                                          pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  char *chlg64 = data->state.buffer;
+  size_t len = 0;
+  char *rplyb64 = NULL;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied: %d", pop3code);
+    return CURLE_LOGIN_DENIED;
+  }
+
+  /* Get the challenge */
+  for(chlg64 += 2; *chlg64 == ' ' || *chlg64 == '\t'; chlg64++)
+    ;
+
+  /* Terminate the challenge */
+  if(*chlg64 != '=') {
+    for(len = strlen(chlg64); len--;)
+      if(chlg64[len] != '\r' && chlg64[len] != '\n' && chlg64[len] != ' ' &&
+         chlg64[len] != '\t')
+        break;
+
+    if(++len) {
+      chlg64[len] = '\0';
+    }
+  }
+
+  /* Create the response message */
+  result = Curl_sasl_create_cram_md5_message(data, chlg64, conn->user,
+                                             conn->passwd, &rplyb64, &len);
+
+  /* Send the response */
+  if(!result) {
+    if(rplyb64) {
+      result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", rplyb64);
+
+      if(!result)
+        state(conn, POP3_AUTH_FINAL);
+    }
+
+    Curl_safefree(rplyb64);
+  }
+
+  return result;
+}
+
+/* For AUTH DIGEST-MD5 challenge responses */
+static CURLcode pop3_state_auth_digest_resp(struct connectdata *conn,
+                                            int pop3code,
+                                            pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  char *chlg64 = data->state.buffer;
+  size_t len = 0;
+  char *rplyb64 = NULL;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied: %d", pop3code);
+    return CURLE_LOGIN_DENIED;
+  }
+
+  /* Get the challenge */
+  for(chlg64 += 2; *chlg64 == ' ' || *chlg64 == '\t'; chlg64++)
+    ;
+
+  /* Create the response message */
+  result = Curl_sasl_create_digest_md5_message(data, chlg64, conn->user,
+                                               conn->passwd, "pop",
+                                               &rplyb64, &len);
+
+  /* Send the response */
+  if(!result) {
+    if(rplyb64) {
+      result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", rplyb64);
+
+      if(!result)
+        state(conn, POP3_AUTH_DIGESTMD5_RESP);
+    }
+
+    Curl_safefree(rplyb64);
+  }
+
+  return result;
+}
+
+/* For AUTH DIGEST-MD5 challenge-response responses */
+static CURLcode pop3_state_auth_digest_resp_resp(struct connectdata *conn,
+                                                 int pop3code,
+                                                 pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Authentication failed: %d", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else {
+    /* Send an empty response */
+    result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", "");
+
+    if(!result)
+      state(conn, POP3_AUTH_FINAL);
+  }
+
+  return result;
+}
+#endif
+
+#ifdef USE_NTLM
+/* For AUTH NTLM (without initial response) responses */
+static CURLcode pop3_state_auth_ntlm_resp(struct connectdata *conn,
+                                          int pop3code,
+                                          pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  size_t len = 0;
+  char *type1msg = NULL;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied: %d", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else {
+    /* Create the type-1 message */
+    result = Curl_sasl_create_ntlm_type1_message(conn->user, conn->passwd,
+                                                 &conn->ntlm,
+                                                 &type1msg, &len);
+
+    /* Send the message */
+    if(!result) {
+      if(type1msg) {
+        result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", type1msg);
+
+        if(!result)
+          state(conn, POP3_AUTH_NTLM_TYPE2MSG);
+      }
+
+      Curl_safefree(type1msg);
+    }
+  }
+
+  return result;
+}
+
+/* For NTLM type-2 responses (sent in reponse to our type-1 message) */
+static CURLcode pop3_state_auth_ntlm_type2msg_resp(struct connectdata *conn,
+                                                   int pop3code,
+                                                   pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  size_t len = 0;
+  char *type3msg = NULL;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied: %d", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else {
+    /* Create the type-3 message */
+    result = Curl_sasl_create_ntlm_type3_message(data,
+                                                 data->state.buffer + 2,
+                                                 conn->user, conn->passwd,
+                                                 &conn->ntlm,
+                                                 &type3msg, &len);
+
+    /* Send the message */
+    if(!result) {
+      if(type3msg) {
+        result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", type3msg);
+
+        if(!result)
+          state(conn, POP3_AUTH_FINAL);
+      }
+
+      Curl_safefree(type3msg);
+    }
+  }
+
+  return result;
+}
+#endif
+
+/* For AUTH XOAUTH2 (without initial response) responses */
+static CURLcode pop3_state_auth_xoauth2_resp(struct connectdata *conn,
+                                             int pop3code, pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  size_t len = 0;
+  char *xoauth = NULL;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied: %d", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else {
+    /* Create the authorisation message */
+    result = Curl_sasl_create_xoauth2_message(conn->data, conn->user,
+                                              conn->xoauth2_bearer,
+                                              &xoauth, &len);
+
+    /* Send the message */
+    if(!result) {
+      if(xoauth) {
+        result = Curl_pp_sendf(&conn->proto.pop3c.pp, "%s", xoauth);
+
+        if(!result)
+          state(conn, POP3_AUTH_FINAL);
+      }
+
+      Curl_safefree(xoauth);
+    }
+  }
+
+  return result;
+}
+
+/* For final responses to the AUTH sequence */
+static CURLcode pop3_state_auth_final_resp(struct connectdata *conn,
+                                           int pop3code,
+                                           pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Authentication failed: %d", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else
+    /* End of connect phase */
+    state(conn, POP3_STOP);
+
+  return result;
+}
+
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+/* For APOP responses */
+static CURLcode pop3_state_apop_resp(struct connectdata *conn, int pop3code,
+                                     pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Authentication failed: %d", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else
+    /* End of connect phase */
+    state(conn, POP3_STOP);
+
+  return result;
+}
+#endif
+
+/* For USER responses */
+static CURLcode pop3_state_user_resp(struct connectdata *conn, int pop3code,
+                                     pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied. %c", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else
+    /* Send the PASS command */
+    result = Curl_pp_sendf(&conn->proto.pop3c.pp, "PASS %s",
+                           conn->passwd ? conn->passwd : "");
+  if(!result)
+    state(conn, POP3_PASS);
+
+  return result;
+}
+
+/* For PASS responses */
+static CURLcode pop3_state_pass_resp(struct connectdata *conn, int pop3code,
+                                     pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    failf(data, "Access denied. %c", pop3code);
+    result = CURLE_LOGIN_DENIED;
+  }
+  else
+    /* End of connect phase */
+    state(conn, POP3_STOP);
+
+  return result;
+}
+
+/* For command responses */
+static CURLcode pop3_state_command_resp(struct connectdata *conn,
+                                        int pop3code,
+                                        pop3state instate)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  struct POP3 *pop3 = data->req.protop;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+  struct pingpong *pp = &pop3c->pp;
+
+  (void)instate; /* no use for this yet */
+
+  if(pop3code != '+') {
+    state(conn, POP3_STOP);
+    return CURLE_RECV_ERROR;
+  }
+
+  /* This 'OK' line ends with a CR LF pair which is the two first bytes of the
+     EOB string so count this is two matching bytes. This is necessary to make
+     the code detect the EOB if the only data than comes now is %2e CR LF like
+     when there is no body to return. */
+  pop3c->eob = 2;
+
+  /* But since this initial CR LF pair is not part of the actual body, we set
+     the strip counter here so that these bytes won't be delivered. */
+  pop3c->strip = 2;
+
+  if(pop3->transfer == FTPTRANSFER_BODY) {
+    /* POP3 download */
+    Curl_setup_transfer(conn, FIRSTSOCKET, -1, FALSE, NULL, -1, NULL);
+
+    if(pp->cache) {
+      /* The header "cache" contains a bunch of data that is actually body
+         content so send it as such. Note that there may even be additional
+         "headers" after the body */
+
+      if(!data->set.opt_no_body) {
+        result = Curl_pop3_write(conn, pp->cache, pp->cache_size);
+        if(result)
+          return result;
+      }
+
+      /* Free the cache */
+      Curl_safefree(pp->cache);
+
+      /* Reset the cache size */
+      pp->cache_size = 0;
+    }
+  }
+
+  /* End of DO phase */
+  state(conn, POP3_STOP);
+
+  return result;
+}
+
+static CURLcode pop3_statemach_act(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  curl_socket_t sock = conn->sock[FIRSTSOCKET];
+  int pop3code;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+  struct pingpong *pp = &pop3c->pp;
+  size_t nread = 0;
+
+  /* Busy upgrading the connection; right now all I/O is SSL/TLS, not POP3 */
+  if(pop3c->state == POP3_UPGRADETLS)
+    return pop3_perform_upgrade_tls(conn);
+
+  /* Flush any data that needs to be sent */
+  if(pp->sendleft)
+    return Curl_pp_flushsend(pp);
+
+  /* Read the response from the server */
+  result = Curl_pp_readresp(sock, pp, &pop3code, &nread);
+  if(result)
+    return result;
+
+  if(pop3code) {
+    /* We have now received a full POP3 server response */
+    switch(pop3c->state) {
+    case POP3_SERVERGREET:
+      result = pop3_state_servergreet_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_CAPA:
+      result = pop3_state_capa_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_STARTTLS:
+      result = pop3_state_starttls_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_AUTH_PLAIN:
+      result = pop3_state_auth_plain_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_AUTH_LOGIN:
+      result = pop3_state_auth_login_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_AUTH_LOGIN_PASSWD:
+      result = pop3_state_auth_login_password_resp(conn, pop3code,
+                                                   pop3c->state);
+      break;
+
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+    case POP3_AUTH_CRAMMD5:
+      result = pop3_state_auth_cram_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_AUTH_DIGESTMD5:
+      result = pop3_state_auth_digest_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_AUTH_DIGESTMD5_RESP:
+      result = pop3_state_auth_digest_resp_resp(conn, pop3code, pop3c->state);
+      break;
+#endif
+
+#ifdef USE_NTLM
+    case POP3_AUTH_NTLM:
+      result = pop3_state_auth_ntlm_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_AUTH_NTLM_TYPE2MSG:
+      result = pop3_state_auth_ntlm_type2msg_resp(conn, pop3code,
+                                                  pop3c->state);
+      break;
+#endif
+
+    case POP3_AUTH_XOAUTH2:
+      result = pop3_state_auth_xoauth2_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_AUTH_FINAL:
+      result = pop3_state_auth_final_resp(conn, pop3code, pop3c->state);
+      break;
+
+#ifndef CURL_DISABLE_CRYPTO_AUTH
+    case POP3_APOP:
+      result = pop3_state_apop_resp(conn, pop3code, pop3c->state);
+      break;
+#endif
+
+    case POP3_USER:
+      result = pop3_state_user_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_PASS:
+      result = pop3_state_pass_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_COMMAND:
+      result = pop3_state_command_resp(conn, pop3code, pop3c->state);
+      break;
+
+    case POP3_QUIT:
+      /* fallthrough, just stop! */
+    default:
+      /* internal error */
+      state(conn, POP3_STOP);
+      break;
+    }
+  }
+
+  return result;
+}
+
+/* Called repeatedly until done from multi.c */
+static CURLcode pop3_multi_statemach(struct connectdata *conn, bool *done)
+{
+  CURLcode result = CURLE_OK;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+
+  if((conn->handler->flags & PROTOPT_SSL) && !pop3c->ssldone) {
+    result = Curl_ssl_connect_nonblocking(conn, FIRSTSOCKET, &pop3c->ssldone);
+    if(result || !pop3c->ssldone)
+      return result;
+  }
+
+  result = Curl_pp_statemach(&pop3c->pp, FALSE);
+  *done = (pop3c->state == POP3_STOP) ? TRUE : FALSE;
+
+  return result;
+}
+
+static CURLcode pop3_block_statemach(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+
+  while(pop3c->state != POP3_STOP && !result)
+    result = Curl_pp_statemach(&pop3c->pp, TRUE);
+
+  return result;
+}
+
+/* Allocate and initialize the POP3 struct for the current SessionHandle if
+   required */
+static CURLcode pop3_init(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  struct POP3 *pop3;
+
+  pop3 = data->req.protop = calloc(sizeof(struct POP3), 1);
+  if(!pop3)
+    result = CURLE_OUT_OF_MEMORY;
+
+  return result;
+}
+
+/* For the POP3 "protocol connect" and "doing" phases only */
+static int pop3_getsock(struct connectdata *conn, curl_socket_t *socks,
+                        int numsocks)
+{
+  return Curl_pp_getsock(&conn->proto.pop3c.pp, socks, numsocks);
+}
+
+/***********************************************************************
+ *
+ * pop3_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 pop3_connect(struct connectdata *conn, bool *done)
+{
+  CURLcode result = CURLE_OK;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+  struct pingpong *pp = &pop3c->pp;
+
+  *done = FALSE; /* default to not done yet */
+
+  /* We always support persistent connections in POP3 */
+  conn->bits.close = FALSE;
+
+  /* Set the default response time-out */
+  pp->response_time = RESP_TIMEOUT;
+  pp->statemach_act = pop3_statemach_act;
+  pp->endofresp = pop3_endofresp;
+  pp->conn = conn;
+
+  /* Set the default preferred authentication type and mechanism */
+  pop3c->preftype = POP3_TYPE_ANY;
+  pop3c->prefmech = SASL_AUTH_ANY;
+
+  /* Initialise the pingpong layer */
+  Curl_pp_init(pp);
+
+  /* Parse the URL options */
+  result = pop3_parse_url_options(conn);
+  if(result)
+    return result;
+
+  /* Start off waiting for the server greeting response */
+  state(conn, POP3_SERVERGREET);
+
+  result = pop3_multi_statemach(conn, done);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_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 pop3_done(struct connectdata *conn, CURLcode status,
+                          bool premature)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  struct POP3 *pop3 = data->req.protop;
+
+  (void)premature;
+
+  if(!pop3)
+    /* When the easy handle is removed from the multi interface while libcurl
+       is still trying to resolve the host name, the POP3 struct is not yet
+       initialized. However, the removal action calls Curl_done() which in
+       turn calls this function, so we simply return success. */
+    return CURLE_OK;
+
+  if(status) {
+    conn->bits.close = TRUE; /* marked for closure */
+    result = status;         /* use the already set error code */
+  }
+
+  /* Cleanup our per-request based variables */
+  Curl_safefree(pop3->id);
+  Curl_safefree(pop3->custom);
+
+  /* Clear the transfer mode for the next request */
+  pop3->transfer = FTPTRANSFER_BODY;
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_perform()
+ *
+ * This is the actual DO function for POP3. Get a message/listing according to
+ * the options previously setup.
+ */
+static CURLcode pop3_perform(struct connectdata *conn, bool *connected,
+                             bool *dophase_done)
+{
+  /* This is POP3 and no proxy */
+  CURLcode result = CURLE_OK;
+
+  DEBUGF(infof(conn->data, "DO phase starts\n"));
+
+  if(conn->data->set.opt_no_body) {
+    /* Requested no body means no transfer */
+    struct POP3 *pop3 = conn->data->req.protop;
+    pop3->transfer = FTPTRANSFER_INFO;
+  }
+
+  *dophase_done = FALSE; /* not done yet */
+
+  /* Start the first command in the DO phase */
+  result = pop3_perform_command(conn);
+  if(result)
+    return result;
+
+  /* Run the state-machine */
+  result = pop3_multi_statemach(conn, dophase_done);
+
+  *connected = conn->bits.tcpconnect[FIRSTSOCKET];
+
+  if(*dophase_done)
+    DEBUGF(infof(conn->data, "DO phase is complete\n"));
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_do()
+ *
+ * This function is registered as 'curl_do' function. It decodes the path
+ * parts etc as a wrapper to the actual DO function (pop3_perform).
+ *
+ * The input argument is already checked for validity.
+ */
+static CURLcode pop3_do(struct connectdata *conn, bool *done)
+{
+  CURLcode result = CURLE_OK;
+
+  *done = FALSE; /* default to false */
+
+  /* Parse the URL path */
+  result = pop3_parse_url_path(conn);
+  if(result)
+    return result;
+
+  /* Parse the custom request */
+  result = pop3_parse_custom_request(conn);
+  if(result)
+    return result;
+
+  result = pop3_regular_transfer(conn, done);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_disconnect()
+ *
+ * Disconnect from an POP3 server. Cleanup protocol-specific per-connection
+ * resources. BLOCKING.
+ */
+static CURLcode pop3_disconnect(struct connectdata *conn,
+                                bool dead_connection)
+{
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+
+  /* 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 POP3 session may or may not have been allocated/setup at this
+     point! */
+  if(!dead_connection && pop3c->pp.conn)
+    if(!pop3_perform_quit(conn))
+      (void)pop3_block_statemach(conn); /* ignore errors on QUIT */
+
+  /* Disconnect from the server */
+  Curl_pp_disconnect(&pop3c->pp);
+
+  /* Cleanup the SASL module */
+  Curl_sasl_cleanup(conn, pop3c->authused);
+
+  /* Cleanup our connection based variables */
+  Curl_safefree(pop3c->apoptimestamp);
+
+  return CURLE_OK;
+}
+
+/* Call this when the DO phase has completed */
+static CURLcode pop3_dophase_done(struct connectdata *conn, bool connected)
+{
+  (void)conn;
+  (void)connected;
+
+  return CURLE_OK;
+}
+
+/* Called from multi.c while DOing */
+static CURLcode pop3_doing(struct connectdata *conn, bool *dophase_done)
+{
+  CURLcode result = pop3_multi_statemach(conn, dophase_done);
+
+  if(result)
+    DEBUGF(infof(conn->data, "DO phase failed\n"));
+  else if(*dophase_done) {
+    result = pop3_dophase_done(conn, FALSE /* not connected */);
+
+    DEBUGF(infof(conn->data, "DO phase is complete\n"));
+  }
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_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 pop3_regular_transfer(struct connectdata *conn,
+                                      bool *dophase_done)
+{
+  CURLcode result = CURLE_OK;
+  bool connected = FALSE;
+  struct SessionHandle *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, 0);
+  Curl_pgrsSetDownloadSize(data, 0);
+
+  /* Carry out the perform */
+  result = pop3_perform(conn, &connected, dophase_done);
+
+  /* Perform post DO phase operations if necessary */
+  if(!result && *dophase_done)
+    result = pop3_dophase_done(conn, connected);
+
+  return result;
+}
+
+static CURLcode pop3_setup_connection(struct connectdata *conn)
+{
+  struct SessionHandle *data = conn->data;
+
+  /* Initialise the POP3 layer */
+  CURLcode result = pop3_init(conn);
+  if(result)
+    return result;
+
+  if(conn->bits.httpproxy && !data->set.tunnel_thru_httpproxy) {
+    /* Unless we have asked to tunnel POP3 operations through the proxy, we
+       switch and use HTTP operations only */
+#ifndef CURL_DISABLE_HTTP
+    if(conn->handler == &Curl_handler_pop3)
+      conn->handler = &Curl_handler_pop3_proxy;
+    else {
+#ifdef USE_SSL
+      conn->handler = &Curl_handler_pop3s_proxy;
+#else
+      failf(data, "POP3S not supported!");
+      return CURLE_UNSUPPORTED_PROTOCOL;
+#endif
+    }
+
+    /* set it up as an HTTP connection instead */
+    return conn->handler->setup_connection(conn);
+#else
+    failf(data, "POP3 over http proxy requires HTTP support built-in!");
+    return CURLE_UNSUPPORTED_PROTOCOL;
+#endif
+  }
+
+  data->state.path++;   /* don't include the initial slash */
+
+  return CURLE_OK;
+}
+
+/***********************************************************************
+ *
+ * pop3_parse_url_options()
+ *
+ * Parse the URL login options.
+ */
+static CURLcode pop3_parse_url_options(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+  const char *options = conn->options;
+  const char *ptr = options;
+
+  if(options) {
+    const char *key = ptr;
+
+    while(*ptr && *ptr != '=')
+        ptr++;
+
+    if(strnequal(key, "AUTH", 4)) {
+      const char *value = ptr + 1;
+
+      if(strequal(value, "*")) {
+        pop3c->preftype = POP3_TYPE_ANY;
+        pop3c->prefmech = SASL_AUTH_ANY;
+      }
+      else if(strequal(value, "+APOP")) {
+        pop3c->preftype = POP3_TYPE_APOP;
+        pop3c->prefmech = SASL_AUTH_NONE;
+      }
+      else if(strequal(value, SASL_MECH_STRING_LOGIN)) {
+        pop3c->preftype = POP3_TYPE_SASL;
+        pop3c->prefmech = SASL_MECH_LOGIN;
+      }
+      else if(strequal(value, SASL_MECH_STRING_PLAIN)) {
+        pop3c->preftype = POP3_TYPE_SASL;
+        pop3c->prefmech = SASL_MECH_PLAIN;
+      }
+      else if(strequal(value, SASL_MECH_STRING_CRAM_MD5)) {
+        pop3c->preftype = POP3_TYPE_SASL;
+        pop3c->prefmech = SASL_MECH_CRAM_MD5;
+      }
+      else if(strequal(value, SASL_MECH_STRING_DIGEST_MD5)) {
+        pop3c->preftype = POP3_TYPE_SASL;
+        pop3c->prefmech = SASL_MECH_DIGEST_MD5;
+      }
+      else if(strequal(value, SASL_MECH_STRING_GSSAPI)) {
+        pop3c->preftype = POP3_TYPE_SASL;
+        pop3c->prefmech = SASL_MECH_GSSAPI;
+      }
+      else if(strequal(value, SASL_MECH_STRING_NTLM)) {
+        pop3c->preftype = POP3_TYPE_SASL;
+        pop3c->prefmech = SASL_MECH_NTLM;
+      }
+      else if(strequal(value, SASL_MECH_STRING_XOAUTH2)) {
+        pop3c->preftype = POP3_TYPE_SASL;
+        pop3c->prefmech = SASL_MECH_XOAUTH2;
+      }
+      else {
+        pop3c->preftype = POP3_TYPE_NONE;
+        pop3c->prefmech = SASL_AUTH_NONE;
+      }
+    }
+    else
+      result = CURLE_URL_MALFORMAT;
+  }
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * pop3_parse_url_path()
+ *
+ * Parse the URL path into separate path components.
+ */
+static CURLcode pop3_parse_url_path(struct connectdata *conn)
+{
+  /* The POP3 struct is already initialised in pop3_connect() */
+  struct SessionHandle *data = conn->data;
+  struct POP3 *pop3 = data->req.protop;
+  const char *path = data->state.path;
+
+  /* URL decode the path for the message ID */
+  return Curl_urldecode(data, path, 0, &pop3->id, NULL, TRUE);
+}
+
+/***********************************************************************
+ *
+ * pop3_parse_custom_request()
+ *
+ * Parse the custom request.
+ */
+static CURLcode pop3_parse_custom_request(struct connectdata *conn)
+{
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  struct POP3 *pop3 = data->req.protop;
+  const char *custom = data->set.str[STRING_CUSTOMREQUEST];
+
+  /* URL decode the custom request */
+  if(custom)
+    result = Curl_urldecode(data, custom, 0, &pop3->custom, NULL, TRUE);
+
+  return result;
+}
+
+/***********************************************************************
+ *
+ * Curl_pop3_write()
+ *
+ * This function scans the body after the end-of-body and writes everything
+ * until the end is found.
+ */
+CURLcode Curl_pop3_write(struct connectdata *conn, char *str, size_t nread)
+{
+  /* This code could be made into a special function in the handler struct */
+  CURLcode result = CURLE_OK;
+  struct SessionHandle *data = conn->data;
+  struct SingleRequest *k = &data->req;
+
+  struct pop3_conn *pop3c = &conn->proto.pop3c;
+  bool strip_dot = FALSE;
+  size_t last = 0;
+  size_t i;
+
+  /* Search through the buffer looking for the end-of-body marker which is
+     5 bytes (0d 0a 2e 0d 0a). Note that a line starting with a dot matches
+     the eob so the server will have prefixed it with an extra dot which we
+     need to strip out. Additionally the marker could of course be spread out
+     over 5 different data chunks. */
+  for(i = 0; i < nread; i++) {
+    size_t prev = pop3c->eob;
+
+    switch(str[i]) {
+    case 0x0d:
+      if(pop3c->eob == 0) {
+        pop3c->eob++;
+
+        if(i) {
+          /* Write out the body part that didn't match */
+          result = Curl_client_write(conn, CLIENTWRITE_BODY, &str[last],
+                                     i - last);
+
+          if(result)
+            return result;
+
+          last = i;
+        }
+      }
+      else if(pop3c->eob == 3)
+        pop3c->eob++;
+      else
+        /* If the character match wasn't at position 0 or 3 then restart the
+           pattern matching */
+        pop3c->eob = 1;
+      break;
+
+    case 0x0a:
+      if(pop3c->eob == 1 || pop3c->eob == 4)
+        pop3c->eob++;
+      else
+        /* If the character match wasn't at position 1 or 4 then start the
+           search again */
+        pop3c->eob = 0;
+      break;
+
+    case 0x2e:
+      if(pop3c->eob == 2)
+        pop3c->eob++;
+      else if(pop3c->eob == 3) {
+        /* We have an extra dot after the CRLF which we need to strip off */
+        strip_dot = TRUE;
+        pop3c->eob = 0;
+      }
+      else
+        /* If the character match wasn't at position 2 then start the search
+           again */
+        pop3c->eob = 0;
+      break;
+
+    default:
+      pop3c->eob = 0;
+      break;
+    }
+
+    /* Did we have a partial match which has subsequently failed? */
+    if(prev && prev >= pop3c->eob) {
+      /* Strip can only be non-zero for the very first mismatch after CRLF
+         and then both prev and strip are equal and nothing will be output
+         below */
+      while(prev && pop3c->strip) {
+        prev--;
+        pop3c->strip--;
+      }
+
+      if(prev) {
+        /* If the partial match was the CRLF and dot then only write the CRLF
+           as the server would have inserted the dot */
+        result = Curl_client_write(conn, CLIENTWRITE_BODY, (char*)POP3_EOB,
+                                   strip_dot ? prev - 1 : prev);
+
+        if(result)
+          return result;
+
+        last = i;
+        strip_dot = FALSE;
+      }
+    }
+  }
+
+  if(pop3c->eob == POP3_EOB_LEN) {
+    /* We have a full match so the transfer is done, however we must transfer
+    the CRLF at the start of the EOB as this is considered to be part of the
+    message as per RFC-1939, sect. 3 */
+    result = Curl_client_write(conn, CLIENTWRITE_BODY, (char *)POP3_EOB, 2);
+
+    k->keepon &= ~KEEP_RECV;
+    pop3c->eob = 0;
+
+    return result;
+  }
+
+  if(pop3c->eob)
+    /* While EOB is matching nothing should be output */
+    return CURLE_OK;
+
+  if(nread - last) {
+    result = Curl_client_write(conn, CLIENTWRITE_BODY, &str[last],
+                               nread - last);
+  }
+
+  return result;
+}
+
+#endif /* CURL_DISABLE_POP3 */