From 0e1eaa525a8f4e7d5aa99a615217437e73c3c9b7 Mon Sep 17 00:00:00 2001
From: Alexey Melnichuk <alexeymelnichuck@gmail.com>
Date: Thu, 12 Oct 2017 14:22:24 +0300
Subject: [PATCH] Add. New cURL MIME API

---
 .travis.yml                       |  28 +-
 appveyor.yml                      |   2 +-
 examples/lcurl/smtp-mime.lua      |  85 ++++++
 rockspecs/lua-curl-scm-0.rockspec |   2 +-
 src/lceasy.c                      |  95 +++++-
 src/lceasy.h                      |  21 +-
 src/lcmime.c                      | 479 ++++++++++++++++++++++++++++++
 src/lcmime.h                      |  66 ++++
 src/lcopteasy.h                   |   4 +
 src/lcurl.c                       |   8 +-
 src/lcutils.c                     |  12 +-
 src/lcutils.h                     |   2 +
 test/run.lua                      |   1 +
 test/test_curl.lua                |  30 +-
 test/test_easy.lua                |  65 +---
 test/test_form.lua                |  70 +++--
 test/test_mime.lua                | 188 ++++++++++++
 test/utils.lua                    |  89 ++++++
 18 files changed, 1116 insertions(+), 131 deletions(-)
 create mode 100644 examples/lcurl/smtp-mime.lua
 create mode 100644 src/lcmime.c
 create mode 100644 src/lcmime.h
 create mode 100644 test/test_mime.lua
 create mode 100644 test/utils.lua

diff --git a/.travis.yml b/.travis.yml
index 098c160..7e0facd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,23 +9,17 @@ env:
 
 matrix:
   include:
-    - compiler: ": Lua51-osx"
-      env: LUA="lua 5.1"
+    - env: LUA="lua 5.1"
       os: osx
-    - compiler: ": Lua51"
-      env: LUA="lua 5.1"
+    - env: LUA="lua 5.1"
       os: linux
-    - compiler: ": Lua52"
-      env: LUA="lua 5.2"
+    - env: LUA="lua 5.2"
       os: linux
-    - compiler: ": Lua53"
-      env: LUA="lua 5.3"
+    - env: LUA="lua 5.3"
       os: linux
-    - compiler: ": LuaJIT20"
-      env: LUA="luajit 2.0"
+    - env: LUA="luajit 2.0"
       os: linux
-    - compiler: ": LuaJIT21"
-      env: LUA="luajit 2.1"
+    - env: LUA="luajit 2.1"
       os: linux
 
 cache:
@@ -36,10 +30,9 @@ cache:
 branches:
   only:
     - master
+    - curl_mime
 
 before_install:
-  - export CC=gcc
-  - gcc --version
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then export PATH=$PATH:~/Library/Python/2.7/bin/; fi
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then export LCURL_LD_FLAGS="-bundle -undefined dynamic_lookup -all_load --coverage"; fi
   - pip install --user cpp-coveralls
@@ -68,6 +61,13 @@ script:
   # - lunit.sh test_form.lua
   # - lunit.sh test_curl.lua
 
+before_cache:
+  # - cd $TRAVIS_BUILD_DIR/test
+  # - coveralls -b .. -r .. --dump c.report.json
+  # - luacov-coveralls -j c.report.json -v
+  # - luarocks remove lluv-gsmmodem
+  # - rm -f /home/travis/.cache/pip/log/debug.log
+
 after_success:
   - coveralls -b .. -r .. --dump c.report.json
   - luacov-coveralls -j c.report.json -v
diff --git a/appveyor.yml b/appveyor.yml
index f3446e4..08190a5 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -7,7 +7,7 @@ shallow_clone: true
 
 environment:
   LR_EXTERNAL: c:\external
-  CURL_VER: 7.55.1
+  CURL_VER: 7.56.0
 
   matrix:
   - LUA: "lua 5.1"
diff --git a/examples/lcurl/smtp-mime.lua b/examples/lcurl/smtp-mime.lua
new file mode 100644
index 0000000..f829726
--- /dev/null
+++ b/examples/lcurl/smtp-mime.lua
@@ -0,0 +1,85 @@
+local curl = require "lcurl"
+
+local SMTP = {
+  url      = "smtp://mail.example.com";
+}
+
+local FROM      = "<sender@example.org>"
+local TO        = "<addressee@example.net>"
+local CC        = "<info@example.org>"
+local FILE      = "smtp-mime.lua" -- if you send this file do not forget it may have mail password
+local CT_FILE   = "application/lua"
+
+local DUMP_MIME = false
+
+local headers = {
+  "Date: Tue, 22 Aug 2017 14:08:43 +0100",
+  "To: "   .. TO,
+  "From: " .. FROM .. " (Example User)",
+  "Cc: "   .. CC   .. " (Another example User)",
+  "Message-ID: <dcd7cb36-11db-487a-9f3a-e652a9458efd@rfcpedant.example.org>",
+  "Subject: example sending a MIME-formatted message",
+}
+
+local inline_text = ""
+  .. "This is the inline text message of the e-mail.\r\n"
+  .. "\r\n"
+  .. "  It could be a lot of lines that would be displayed in an e-mail\r\n"
+  .. "viewer that is not able to handle HTML.\r\n"
+
+local inline_html = ""
+  .. "<html><body>\r\n"
+  .. "<p>This is the inline <b>HTML</b> message of the e-mail.</p>"
+  .. "<br />\r\n"
+  .. "<p>It could be a lot of HTML data that would be displayed by "
+  .. "e-mail viewers able to handle HTML.</p>"
+  .. "</body></html>\r\n"
+
+local function dump_mime(type, data)
+  if type == curl.INFO_DATA_OUT then io.write(data) end
+end
+
+local easy = curl.easy()
+
+local mime = easy:mime() do
+  local alt = easy:mime()
+  alt
+    :addpart()
+      :data(inline_html, "text/html")
+  alt
+    :addpart()
+      :data(inline_text)
+  mime:addpart()
+    :subparts(alt, "multipart/alternative", {
+      "Content-Disposition: inline"
+    })
+  mime
+    :addpart()
+      :filedata(FILE, CT_FILE)
+end
+
+easy:setopt{
+  url            = SMTP.url,
+  mail_from      = FROM,
+  mail_rcpt      = {TO, CC},
+  httpheader     = headers;
+  mimepost       = mime;
+  ssl_verifyhost = false;
+  ssl_verifypeer = false;
+  username       = SMTP.user;
+  password       = SMTP.password;
+  upload         = true;
+}
+
+if DUMP_MIME then
+  easy:setopt{
+    verbose        = true;
+    debugfunction  = dump_mime;
+  }
+end
+
+easy:perform()
+
+easy:close()
+
+mime:free()
diff --git a/rockspecs/lua-curl-scm-0.rockspec b/rockspecs/lua-curl-scm-0.rockspec
index 22f5a00..2f284a8 100644
--- a/rockspecs/lua-curl-scm-0.rockspec
+++ b/rockspecs/lua-curl-scm-0.rockspec
@@ -63,7 +63,7 @@ build = {
       sources = {
         "src/l52util.c",    "src/lceasy.c", "src/lcerror.c",
         "src/lchttppost.c", "src/lcurl.c",  "src/lcutils.c",
-        "src/lcmulti.c",    "src/lcshare.c",
+        "src/lcmulti.c",    "src/lcshare.c","src/lcmime.c",
       },
       incdirs   = { "$(CURL_INCDIR)" },
       libdirs   = { "$(CURL_LIBDIR)" }
diff --git a/src/lceasy.c b/src/lceasy.c
index f3a7cac..936a286 100644
--- a/src/lceasy.c
+++ b/src/lceasy.c
@@ -1,7 +1,7 @@
 /******************************************************************************
 * Author: Alexey Melnichuk <mimir@newmail.ru>
 *
-* Copyright (C) 2014 Alexey Melnichuk <mimir@newmail.ru>
+* Copyright (C) 2014-2017 Alexey Melnichuk <mimir@newmail.ru>
 *
 * Licensed according to the included 'LICENSE' document
 *
@@ -15,6 +15,7 @@
 #include "lchttppost.h"
 #include "lcshare.h"
 #include "lcmulti.h"
+#include "lcmime.h"
 #include <memory.h>
 
 static const char *LCURL_ERROR_TAG = "LCURL_ERROR_TAG";
@@ -29,7 +30,7 @@ static const char *LCURL_EASY = LCURL_EASY_NAME;
 #endif
 
 /* Before call curl_XXX function which can call any callback
- * need set Curren Lua thread pointer in easy/multi contexts.
+ * need set Current Lua thread pointer in easy/multi contexts.
  * But it also possible that we already in callback call.
  * E.g. `curl_easy_pause` function may be called from write callback.
  * and it even may be called in different thread.
@@ -41,7 +42,7 @@ static const char *LCURL_EASY = LCURL_EASY_NAME;
  * ```
  * So we have to restore previews Lua state in callback contexts.
  * But if previews Lua state is NULL then we can just do not set it back.
- * But set it to NULL make esier debug code.
+ * But set it to NULL make easier to debug code.
  */
 void lcurl__easy_assign_lua(lua_State *L, lcurl_easy_t *p, lua_State *value, int assign_multi){
   if(p->multi && assign_multi){
@@ -52,6 +53,11 @@ void lcurl__easy_assign_lua(lua_State *L, lcurl_easy_t *p, lua_State *value, int
     if(p->post){
       p->post->L = value;
     }
+#if LCURL_CURL_VER_GE(7,56,0)
+    if(p->mime){
+      lcurl_mime_set_lua(L, p->mime, value);
+    }
+#endif
   }
 }
 
@@ -74,6 +80,9 @@ int lcurl_easy_create(lua_State *L, int error_mode){
   p->L                = NULL;
   p->post             = NULL;
   p->multi            = NULL;
+#if LCURL_CURL_VER_GE(7,56,0)
+  p->mime             = NULL;
+#endif
   p->storage          = lcurl_storage_init(L);
   p->wr.cb_ref        = p->wr.ud_ref    = LUA_NOREF;
   p->rd.cb_ref        = p->rd.ud_ref    = LUA_NOREF;
@@ -125,6 +134,8 @@ static int lcurl_easy_cleanup(lua_State *L){
 
     // In my tests when I cleanup some easy handle. 
     // timerfunction called only for single multi handle.
+    // Also may be this function may call `close` callback
+    // for `curl_mimepart` structure.
     curL = p->L; lcurl__easy_assign_lua(L, p, L, 1);
     curl_easy_cleanup(p->curl);
 #ifndef LCURL_RESET_NULL_LUA
@@ -135,6 +146,11 @@ static int lcurl_easy_cleanup(lua_State *L){
     p->curl = NULL;
   }
 
+  p->post = NULL;
+#if LCURL_CURL_VER_GE(7,56,0)
+  p->mime = NULL;
+#endif
+
   if(p->storage != LUA_NOREF){
     p->storage = lcurl_storage_free(L, p->storage);
   }
@@ -266,6 +282,15 @@ static int lcurl_easy_reset(lua_State *L){
   return 1;
 }
 
+#if LCURL_CURL_VER_GE(7,56,0)
+
+static int lcurl_easy_mime(lua_State *L){
+  lcurl_easy_t *p = lcurl_geteasy(L);
+  return lcurl_mime_create(L, p->err_mode);
+}
+
+#endif
+
 //{ OPTIONS
 
 //{ set
@@ -447,6 +472,26 @@ static int lcurl_easy_set_STREAM_DEPENDS_E(lua_State *L){
 
 #endif
 
+#if LCURL_CURL_VER_GE(7,56,0)
+
+static int lcurl_easy_set_MIMEPOST(lua_State *L){
+  lcurl_easy_t *p = lcurl_geteasy(L);
+  lcurl_mime_t *mime = lcurl_getmime_at(L, 2);
+  CURLcode code = curl_easy_setopt(p->curl, CURLOPT_MIMEPOST, mime->mime);
+  if(code != CURLE_OK){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, code);
+  }
+
+  lcurl_storage_preserve_iv(L, p->storage, CURLOPT_MIMEPOST, 2);
+
+  p->mime = mime;
+
+  lua_settop(L, 1);
+  return 1;
+}
+
+#endif
+
 //}
 
 //{ unset
@@ -775,6 +820,25 @@ static int lcurl_easy_unset_STREAM_DEPENDS_E(lua_State *L){
 
 #endif
 
+#if LCURL_CURL_VER_GE(7,56,0)
+
+static int lcurl_easy_unset_MIMEPOST(lua_State *L){
+  lcurl_easy_t *p = lcurl_geteasy(L);
+  CURLcode code = curl_easy_setopt(p->curl, CURLOPT_MIMEPOST, NULL);
+  if(code != CURLE_OK){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, code);
+  }
+
+  lcurl_storage_remove_i(L, p->storage, CURLOPT_MIMEPOST);
+
+  p->mime = NULL;
+
+  lua_settop(L, 1);
+  return 1;
+}
+
+#endif
+
 //}
 
 //}
@@ -1004,7 +1068,7 @@ static int lcurl_easy_set_WRITEFUNCTION(lua_State *L){
 
 //{ Reader
 
-static size_t lcurl_read_callback(lua_State *L,
+size_t lcurl_read_callback(lua_State *L,
   lcurl_callback_t *rd, lcurl_read_buffer_t *rbuffer,
   char *buffer, size_t size, size_t nitems
 ){
@@ -1477,6 +1541,9 @@ static int lcurl_easy_setopt(lua_State *L){
 #if LCURL_CURL_VER_GE(7,46,0)
     OPT_ENTRY(stream_depends,    STREAM_DEPENDS,   TTT, 0, 0)
     OPT_ENTRY(stream_depends_e,  STREAM_DEPENDS_E, TTT, 0, 0)
+#endif
+#if LCURL_CURL_VER_GE(7,56,0)
+    OPT_ENTRY(mimepost,          MIMEPOST,         TTT, 0, 0)
 #endif
   }
 #undef OPT_ENTRY
@@ -1511,6 +1578,9 @@ static int lcurl_easy_unsetopt(lua_State *L){
 #if LCURL_CURL_VER_GE(7,46,0)
     OPT_ENTRY(stream_depends,    STREAM_DEPENDS,   TTT, 0, 0)
     OPT_ENTRY(stream_depends_e,  STREAM_DEPENDS_E, TTT, 0, 0)
+#endif
+#if LCURL_CURL_VER_GE(7,56,0)
+    OPT_ENTRY(mimepost,          MIMEPOST,         TTT, 0, 0)
 #endif
   }
 #undef OPT_ENTRY
@@ -1582,7 +1652,7 @@ static const struct luaL_Reg lcurl_easy_methods[] = {
   OPT_ENTRY(seekfunction,      SEEKFUNCTION,     TTT, 0, 0)
   OPT_ENTRY(debugfunction,     DEBUGFUNCTION,    TTT, 0, 0)
 #if LCURL_CURL_VER_GE(7,21,0)
-  OPT_ENTRY(fnmatch_function,  FNMATCH_FUNCTION, TTT, 0, 0)
+  OPT_ENTRY(fnmatch_function,   FNMATCH_FUNCTION,   TTT, 0, 0)
   OPT_ENTRY(chunk_bgn_function, CHUNK_BGN_FUNCTION, TTT, 0, 0)
   OPT_ENTRY(chunk_end_function, CHUNK_END_FUNCTION, TTT, 0, 0)
 #endif
@@ -1590,6 +1660,9 @@ static const struct luaL_Reg lcurl_easy_methods[] = {
   OPT_ENTRY(stream_depends,    STREAM_DEPENDS,   TTT, 0, 0)
   OPT_ENTRY(stream_depends_e,  STREAM_DEPENDS_E, TTT, 0, 0)
 #endif
+#if LCURL_CURL_VER_GE(7,56,0)
+  OPT_ENTRY(mimepost,          MIMEPOST,         TTT, 0, 0)
+#endif
 #undef OPT_ENTRY
 
 #define OPT_ENTRY(L, N, T, S, D) { "unsetopt_"#L, lcurl_easy_unset_##N },
@@ -1604,7 +1677,7 @@ static const struct luaL_Reg lcurl_easy_methods[] = {
   OPT_ENTRY(seekfunction,      SEEKFUNCTION,     TTT, 0, 0)
   OPT_ENTRY(debugfunction,     DEBUGFUNCTION,    TTT, 0, 0)
 #if LCURL_CURL_VER_GE(7,21,0)
-  OPT_ENTRY(fnmatch_function,  FNMATCH_FUNCTION, TTT, 0, 0)
+  OPT_ENTRY(fnmatch_function,   FNMATCH_FUNCTION,   TTT, 0, 0)
   OPT_ENTRY(chunk_bgn_function, CHUNK_BGN_FUNCTION, TTT, 0, 0)
   OPT_ENTRY(chunk_end_function, CHUNK_END_FUNCTION, TTT, 0, 0)
 #endif
@@ -1612,12 +1685,19 @@ static const struct luaL_Reg lcurl_easy_methods[] = {
   OPT_ENTRY(stream_depends,    STREAM_DEPENDS,   TTT, 0, 0)
   OPT_ENTRY(stream_depends_e,  STREAM_DEPENDS_E, TTT, 0, 0)
 #endif
+#if LCURL_CURL_VER_GE(7,56,0)
+  OPT_ENTRY(mimepost,          MIMEPOST,         TTT, 0, 0)
+#endif
 #undef OPT_ENTRY
 
 #define OPT_ENTRY(L, N, T, S) { "getinfo_"#L, lcurl_easy_get_##N },
   #include "lcinfoeasy.h"
 #undef OPT_ENTRY
 
+#if LCURL_CURL_VER_GE(7,56,0)
+  { "mime",       lcurl_easy_mime           },
+#endif
+
   { "pause",      lcurl_easy_pause          },
   { "reset",      lcurl_easy_reset          },
   { "setopt",     lcurl_easy_setopt         },
@@ -1659,6 +1739,9 @@ static const lcurl_const_t lcurl_easy_opt[] = {
   OPT_ENTRY(stream_depends,    STREAM_DEPENDS,   TTT, 0, 0)
   OPT_ENTRY(stream_depends_e,  STREAM_DEPENDS_E, TTT, 0, 0)
 #endif
+#if LCURL_CURL_VER_GE(7,56,0)
+  OPT_ENTRY(mimepost,          MIMEPOST,         TTT, 0, 0)
+#endif
 #undef OPT_ENTRY
 #undef FLG_ENTRY
 
diff --git a/src/lceasy.h b/src/lceasy.h
index e3275f1..916f53d 100644
--- a/src/lceasy.h
+++ b/src/lceasy.h
@@ -1,7 +1,7 @@
 /******************************************************************************
 * Author: Alexey Melnichuk <mimir@newmail.ru>
 *
-* Copyright (C) 2014 Alexey Melnichuk <mimir@newmail.ru>
+* Copyright (C) 2014-2017 Alexey Melnichuk <mimir@newmail.ru>
 *
 * Licensed according to the included 'LICENSE' document
 *
@@ -37,9 +37,16 @@ enum {
 
 #if LCURL_CC_SUPPORT_FORWARD_TYPEDEF
 typedef struct lcurl_multi_tag lcurl_multi_t;
+#if LCURL_CURL_VER_GE(7,56,0)
+typedef struct lcurl_mime_tag lcurl_mime_t;
+#endif
 #else
 struct lcurl_multi_tag;
 #define lcurl_multi_t struct lcurl_multi_tag
+#if LCURL_CURL_VER_GE(7,56,0)
+struct lcurl_mime_tag;
+#define lcurl_mime_t struct lcurl_mime_tag;
+#endif
 #endif
 
 typedef struct lcurl_easy_tag{
@@ -53,6 +60,10 @@ typedef struct lcurl_easy_tag{
 
   lcurl_multi_t *multi;
 
+#if LCURL_CURL_VER_GE(7,56,0)
+  lcurl_mime_t *mime;
+#endif
+
   CURL *curl;
   int storage;
   int lists[LCURL_LIST_COUNT];
@@ -77,8 +88,16 @@ void lcurl_easy_initlib(lua_State *L, int nup);
 
 void lcurl__easy_assign_lua(lua_State *L, lcurl_easy_t *p, lua_State *value, int assign_multi);
 
+size_t lcurl_read_callback(lua_State *L,
+  lcurl_callback_t *rd, lcurl_read_buffer_t *rbuffer,
+  char *buffer, size_t size, size_t nitems
+);
+
 #if !LCURL_CC_SUPPORT_FORWARD_TYPEDEF
 #undef lcurl_multi_t
+#ifdef lcurl_mime_t
+#undef lcurl_mime_t
+#endif
 #endif
 
 #endif
diff --git a/src/lcmime.c b/src/lcmime.c
new file mode 100644
index 0000000..43d221e
--- /dev/null
+++ b/src/lcmime.c
@@ -0,0 +1,479 @@
+/******************************************************************************
+* Author: Alexey Melnichuk <mimir@newmail.ru>
+*
+* Copyright (C) 2017 Alexey Melnichuk <mimir@newmail.ru>
+*
+* Licensed according to the included 'LICENSE' document
+*
+* This file is part of lua-lcurl library.
+******************************************************************************/
+
+#include "lcurl.h"
+#include "lcmime.h"
+#include "lceasy.h"
+#include "lcerror.h"
+#include "lcutils.h"
+
+#if LCURL_CURL_VER_GE(7,56,0)
+
+#define LCURL_MIME_NAME LCURL_PREFIX" MIME"
+static const char *LCURL_MIME = LCURL_MIME_NAME;
+
+#define LCURL_MIME_PART_NAME LCURL_PREFIX" MIME Part"
+static const char *LCURL_MIME_PART = LCURL_MIME_PART_NAME;
+
+static void lcurl_mime_part_remove_subparts(lua_State *L, lcurl_mime_part_t *p, int free_it);
+
+static lcurl_mime_t* lcurl_mime_part_get_subparts(lua_State *L, lcurl_mime_part_t *part){
+  lcurl_mime_t *sub = NULL;
+
+  if(LUA_NOREF != part->subpart_ref){
+    lua_rawgeti(L, LCURL_LUA_REGISTRY, part->subpart_ref);
+    sub = lcurl_getmime_at(L, -1);
+    lua_pop(L, 1);
+  }
+
+  return sub;
+}
+
+static int lcurl_mime_part_reset(lua_State *L, lcurl_mime_part_t *p){
+  p->part = NULL;
+
+  luaL_unref(L, LCURL_LUA_REGISTRY, p->rd.cb_ref);
+  luaL_unref(L, LCURL_LUA_REGISTRY, p->rd.ud_ref);
+  luaL_unref(L, LCURL_LUA_REGISTRY, p->rbuffer.ref);
+
+  p->headers_ref = p->rbuffer.ref = p->rd.cb_ref = p->rd.ud_ref = LUA_NOREF;
+
+  /*free only if we have no parents*/
+  lcurl_mime_part_remove_subparts(L, p, 0);
+
+  return 0;
+}
+
+static int lcurl_mime_reset(lua_State *L, lcurl_mime_t *p){
+  lcurl_mime_part_t *ptr;
+
+  /* reset all parts*/
+  for(ptr = p->parts; ptr; ptr=ptr->next){
+    lcurl_mime_part_reset(L, ptr);
+  }
+
+  if(LUA_NOREF != p->storage){
+    p->storage = lcurl_storage_free(L, p->storage);
+  }
+
+  p->parts = p->parent = NULL;
+  p->mime = NULL;
+
+  return 0;
+}
+
+int lcurl_mime_set_lua(lua_State *L, lcurl_mime_t *p, lua_State *v){
+  lcurl_mime_part_t *part;
+  for(part = p->parts; part; part=part->next){
+    lcurl_mime_t *sub = lcurl_mime_part_get_subparts(L, part);
+    if(sub) lcurl_mime_set_lua(L, sub, v);
+    part->L = v;
+  }
+  return 0;
+}
+
+//{ MIME
+
+static lcurl_mime_part_t* lcurl_mime_parts_append(lcurl_mime_t *m, lcurl_mime_part_t *p){
+  if(!m->parts) m->parts = p;
+  else{
+    lcurl_mime_part_t *ptr = m->parts;
+    while(ptr->next)ptr = ptr->next;
+    ptr->next = p;
+  }
+  return p;
+}
+
+static lcurl_mime_part_t* lcurl_mime_parts_find(lcurl_mime_t *m, lcurl_mime_part_t *p){
+  lcurl_mime_part_t *ptr;
+
+  for(ptr = m->parts; ptr; ptr = ptr->next){
+    if(ptr == p) return p;
+  }
+
+  return NULL;
+}
+
+int lcurl_mime_create(lua_State *L, int error_mode){
+  //! @todo make this function as method of easy handle
+  lcurl_easy_t *e = lcurl_geteasy(L);
+
+  lcurl_mime_t *p = lutil_newudatap(L, lcurl_mime_t, LCURL_MIME);
+
+  p->mime = curl_mime_init(e->curl);
+
+  //! @todo return more accurate error category/code
+  if(!p->mime) return lcurl_fail_ex(L, error_mode, LCURL_ERROR_EASY, CURLE_FAILED_INIT);
+
+  p->storage = lcurl_storage_init(L);
+  p->err_mode = error_mode;
+  p->parts = p->parent = NULL;
+
+  return 1;
+}
+
+lcurl_mime_t *lcurl_getmime_at(lua_State *L, int i){
+  lcurl_mime_t *p = (lcurl_mime_t *)lutil_checkudatap (L, i, LCURL_MIME);
+  luaL_argcheck (L, p != NULL, i, LCURL_MIME_NAME" object expected");
+  luaL_argcheck (L, p->mime != NULL, i, LCURL_MIME_NAME" object freed");
+  return p;
+}
+
+static int lcurl_mime_to_s(lua_State *L){
+  lcurl_mime_t *p = (lcurl_mime_t *)lutil_checkudatap (L, 1, LCURL_MIME);
+  luaL_argcheck (L, p != NULL, 1, LCURL_MIME_NAME" object expected");
+
+  lua_pushfstring(L, LCURL_MIME_NAME" (%p)%s", (void*)p,
+    p->mime ? (p->parent ? " (subpart)" : "") : " (freed)"
+  );
+  return 1;
+}
+
+static int lcurl_mime_free(lua_State *L){
+  lcurl_mime_t *p = (lcurl_mime_t *)lutil_checkudatap (L, 1, LCURL_MIME);
+  luaL_argcheck (L, p != NULL, 1, LCURL_MIME_NAME" object expected");
+
+  if((p->mime) && (NULL == p->parent)){
+    curl_mime_free(p->mime);
+  }
+
+  return lcurl_mime_reset(L, p);
+}
+
+static int lcurl_mime_addpart(lua_State *L){
+  lcurl_mime_t *p = lcurl_getmime(L);
+  int ret = lcurl_mime_part_create(L, p->err_mode);
+  if(ret != 1) return ret;
+
+  /* store mime part in storage */
+  lcurl_storage_preserve_value(L, p->storage, lua_absindex(L, -1));
+  lcurl_mime_parts_append(p, lcurl_getmimepart_at(L, -1));
+  return 1;
+}
+
+//}
+
+//{ MIME Part
+
+int lcurl_mime_part_create(lua_State *L, int error_mode){
+  //! @todo make this function as method of mime handle
+  lcurl_mime_t *m = lcurl_getmime(L);
+
+  lcurl_mime_part_t *p = lutil_newudatap(L, lcurl_mime_part_t, LCURL_MIME_PART);
+
+  p->part = curl_mime_addpart(m->mime);
+
+  //! @todo return more accurate error category/code
+  if(!p->part) return lcurl_fail_ex(L, error_mode, LCURL_ERROR_EASY, CURLE_FAILED_INIT);
+
+  p->rbuffer.ref = p->rd.cb_ref = p->rd.ud_ref = LUA_NOREF;
+  p->err_mode = error_mode;
+  p->subpart_ref = p->headers_ref = LUA_NOREF;
+  p->parent = m;
+
+  return 1;
+}
+
+lcurl_mime_part_t *lcurl_getmimepart_at(lua_State *L, int i){
+  lcurl_mime_part_t *p = (lcurl_mime_part_t *)lutil_checkudatap (L, i, LCURL_MIME_PART);
+  luaL_argcheck (L, p != NULL, i, LCURL_MIME_PART_NAME" object expected");
+  luaL_argcheck (L, p->part != NULL, i, LCURL_MIME_PART_NAME" object freed");
+  return p;
+}
+
+static int lcurl_mime_part_to_s(lua_State *L){
+  lcurl_mime_part_t *p = (lcurl_mime_part_t *)lutil_checkudatap (L, 1, LCURL_MIME_PART);
+  luaL_argcheck (L, p != NULL, 1, LCURL_MIME_PART_NAME" object expected");
+
+  lua_pushfstring(L, LCURL_MIME_PART_NAME" (%p)%s", (void*)p, p->part ? "" : " (freed)");
+  return 1;
+}
+
+static int lcurl_mime_part_free(lua_State *L){
+  lcurl_mime_part_t *p = (lcurl_mime_part_t *)lutil_checkudatap (L, 1, LCURL_MIME_PART);
+  luaL_argcheck (L, p != NULL, 1, LCURL_MIME_PART_NAME" object expected");
+
+  lcurl_mime_part_reset(L, p);
+
+  return 0;
+}
+
+static void lcurl_mime_part_remove_subparts(lua_State *L, lcurl_mime_part_t *p, int free_it){
+  lcurl_mime_t *sub = lcurl_mime_part_get_subparts(L, p);
+  if(sub){
+    assert(LUA_NOREF != p->subpart_ref);
+    /* detach `subpart` mime from current mime part */
+
+    /* if set `sub->parent = NULL` then gc for mime will try free curl_mime_free. */
+    /* So do not set it unless `curl_mime_subparts(p->part, NULL)` does not free mime */
+
+    luaL_unref(L, LCURL_LUA_REGISTRY, p->subpart_ref);
+    p->subpart_ref = LUA_NOREF;
+
+    if(p->part && free_it){
+      curl_mime_subparts(p->part, NULL);
+    }
+
+    /* issues #1961 */
+
+    /* seems curl_mime_subparts(h, NULL) free asubparts.
+      so we have to invalidate all reference to all nested objects (part/mime).
+      NOTE. All resources already feed. So just need set all pointers to NULL
+      and free all Lua resources (like references and storages)
+    */
+    {
+      lcurl_mime_part_t *ptr;
+      /* reset all parts*/
+      for(ptr = sub->parts; ptr; ptr=ptr->next){
+        lcurl_mime_part_remove_subparts(L, p, 0);
+      }
+      lcurl_mime_reset(L, sub);
+    }
+  }
+}
+
+#define IS_NILORSTR(L, i) (lua_type(L, i) == LUA_TSTRING) || (lua_type(L, i) == LUA_TNIL)
+#define IS_TABLE(L, i) lua_type(L, i) == LUA_TTABLE
+
+static int lcurl_mime_part_assing_ext(lua_State *L, lcurl_mime_part_t *p, int i){
+  const char *mime_type = NULL, *mime_name = NULL;
+  int headers = 0;
+  CURLcode ret;
+
+  if(IS_TABLE(L, i)) headers = i;
+  else if(IS_NILORSTR(L, i)){
+    mime_type = lua_tostring(L, i);
+    if(IS_TABLE(L, i+1)) headers = i+1;
+    else if(IS_NILORSTR(L, i+1)){
+      mime_name = lua_tostring(L, i+1);
+      if(IS_TABLE(L, i+2)) headers = i+2;
+    }
+  }
+
+  if(mime_type){
+    ret = curl_mime_type(p->part, mime_type);
+    if(ret != CURLE_OK){
+      return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, ret);
+    }
+  }
+
+  if(mime_name){
+    ret = curl_mime_name(p->part, mime_name);
+    if(ret != CURLE_OK){
+      return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, ret);
+    }
+  }
+
+  if(headers){
+    struct curl_slist *list = lcurl_util_to_slist(L, headers);
+    ret = curl_mime_headers(p->part, list, 1);
+    if(ret != CURLE_OK){
+      curl_slist_free_all(list);
+      return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, ret);
+    }
+  }
+
+  return 0;
+}
+
+// part:data(str[, type[, name]][, headers])
+static int lcurl_mime_part_data(lua_State *L){
+  lcurl_mime_part_t *p = lcurl_getmimepart(L);
+  size_t len; const char *data = luaL_checklstring(L, 2, &len);
+  CURLcode ret;
+
+  /*string too long*/
+  if(len == CURL_ZERO_TERMINATED){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, CURLE_BAD_FUNCTION_ARGUMENT);
+  }
+
+  /* curl_mime_data copies data */
+  ret = curl_mime_data(p->part, data, len);
+  if(ret != CURLE_OK){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, ret);
+  }
+
+  if (lua_gettop(L) > 2){
+    int res = lcurl_mime_part_assing_ext(L, p, 3);
+    if (res) return res;
+  }
+
+  lua_settop(L, 1);
+  return 1;
+}
+
+// part:subparts(mime[, type[, name]][, headers])
+static int lcurl_mime_part_subparts(lua_State *L){
+  lcurl_mime_part_t *p = lcurl_getmimepart(L);
+  lcurl_mime_t *mime = lcurl_getmime_at(L, 2);
+  CURLcode ret;
+
+  /* we can attach mime to only one part */
+  if(mime->parent){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, CURLE_BAD_FUNCTION_ARGUMENT);
+  }
+
+  /* if we already have one subpart then libcurl free it so we can not use any references to it */
+  lcurl_mime_part_remove_subparts(L, p, 1);
+
+  ret = curl_mime_subparts(p->part, mime->mime);
+  if(ret != CURLE_OK){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, ret);
+  }
+
+  lua_pushvalue(L, 2);
+  p->subpart_ref = luaL_ref(L, LCURL_LUA_REGISTRY);
+  mime->parent = p;
+
+  if (lua_gettop(L) > 2){
+    int res = lcurl_mime_part_assing_ext(L, p, 3);
+    if (res) return res;
+  }
+
+  lua_settop(L, 1);
+  return 1;
+}
+
+// part:filedata(path[, type[, name]][, headers])
+static int lcurl_mime_part_filedata(lua_State *L){
+  lcurl_mime_part_t *p = lcurl_getmimepart(L);
+  const char *data = luaL_checkstring(L, 2);
+  CURLcode ret;
+
+  ret = curl_mime_filedata(p->part, data);
+  if(ret != CURLE_OK){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, ret);
+  }
+
+  if (lua_gettop(L) > 2){
+    int res = lcurl_mime_part_assing_ext(L, p, 3);
+    if (res) return res;
+  }
+
+  lua_settop(L, 1);
+  return 1;
+}
+
+// part:headers(t)
+static int lcurl_mime_part_headers(lua_State *L){
+  lcurl_mime_part_t *p = lcurl_getmimepart(L);
+  struct curl_slist *list = lcurl_util_to_slist(L, 2);
+  CURLcode ret;
+
+  luaL_argcheck(L, list, 2, "array expected");
+
+  ret = curl_mime_headers(p->part, list, 1);
+
+  if(ret != CURLE_OK){
+    curl_slist_free_all(list);
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, ret);
+  }
+
+  lua_settop(L, 1);
+  return 1;
+}
+
+// part:type(t)
+static int lcurl_mime_part_type(lua_State *L){
+  lcurl_mime_part_t *p = lcurl_getmimepart(L);
+  const char *mime_type = luaL_checkstring(L, 2);
+  CURLcode ret;
+
+  ret = curl_mime_type(p->part, mime_type);
+
+  if(ret != CURLE_OK){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, ret);
+  }
+
+  lua_settop(L, 1);
+  return 1;
+}
+
+// part:name(t)
+static int lcurl_mime_part_name(lua_State *L){
+  lcurl_mime_part_t *p = lcurl_getmimepart(L);
+  const char *mime_name = luaL_checkstring(L, 2);
+  CURLcode ret;
+
+  ret = curl_mime_name(p->part, mime_name);
+
+  if(ret != CURLE_OK){
+    return lcurl_fail_ex(L, p->err_mode, LCURL_ERROR_EASY, ret);
+  }
+
+  lua_settop(L, 1);
+  return 1;
+}
+
+
+//}
+
+static const struct luaL_Reg lcurl_mime_methods[] = {
+
+  {"addpart",              lcurl_mime_addpart                   },
+
+  {"free",                 lcurl_mime_free                      },
+  {"__gc",                 lcurl_mime_free                      },
+  {"__tostring",           lcurl_mime_to_s                      },
+
+  {NULL,NULL}
+};
+
+static const struct luaL_Reg lcurl_mime_part_methods[] = {
+
+  {"subparts",             lcurl_mime_part_subparts                  },
+  {"data",                 lcurl_mime_part_data                      },
+  {"filedata",             lcurl_mime_part_filedata                  },
+  {"headers",              lcurl_mime_part_headers                   },
+  {"name",                 lcurl_mime_part_name                      },
+  {"type",                 lcurl_mime_part_type                      },
+
+  {"free",                 lcurl_mime_part_free                      },
+  {"__gc",                 lcurl_mime_part_free                      },
+  {"__tostring",           lcurl_mime_part_to_s                      },
+
+  {NULL,NULL}
+};
+
+static int lcurl_pushvalues(lua_State *L, int nup) {
+  assert(lua_gettop(L) >= nup);
+
+  if (nup > 0) {
+    int b = lua_absindex(L, -nup);
+    int e = lua_absindex(L, -1);
+    int i;
+
+    lua_checkstack(L, nup);
+
+    for(i = b; i <= e; ++i)
+      lua_pushvalue(L, i);
+  }
+
+  return nup;
+}
+
+#endif
+
+void lcurl_mime_initlib(lua_State *L, int nup){
+#if LCURL_CURL_VER_GE(7,56,0)
+  lcurl_pushvalues(L, nup);
+
+  if(!lutil_createmetap(L, LCURL_MIME, lcurl_mime_methods, nup))
+    lua_pop(L, nup);
+  lua_pop(L, 1);
+
+  if(!lutil_createmetap(L, LCURL_MIME_PART, lcurl_mime_part_methods, nup))
+    lua_pop(L, nup);
+  lua_pop(L, 1);
+#else
+  lua_pop(L, nup);
+#endif
+}
+
diff --git a/src/lcmime.h b/src/lcmime.h
new file mode 100644
index 0000000..02ebf55
--- /dev/null
+++ b/src/lcmime.h
@@ -0,0 +1,66 @@
+/******************************************************************************
+* Author: Alexey Melnichuk <mimir@newmail.ru>
+*
+* Copyright (C) 2017 Alexey Melnichuk <mimir@newmail.ru>
+*
+* Licensed according to the included 'LICENSE' document
+*
+* This file is part of lua-lcurl library.
+******************************************************************************/
+
+#ifndef _LCMIME_H_
+#define _LCMIME_H_
+
+#include "lcurl.h"
+#include "lcutils.h"
+#include <stdlib.h>
+
+void lcurl_mime_initlib(lua_State *L, int nup);
+
+#if LCURL_CURL_VER_GE(7,56,0)
+
+typedef struct lcurl_mime_part_tag{
+  lua_State           *L;
+
+  lcurl_callback_t    rd;
+  lcurl_read_buffer_t rbuffer;
+
+  curl_mimepart       *part;
+
+  struct lcurl_mime_tag *parent; /*always set and can not be changed*/
+
+  int subpart_ref;
+  int headers_ref;
+
+  int err_mode;
+
+  struct lcurl_mime_part_tag *next;
+}lcurl_mime_part_t;
+
+typedef struct lcurl_mime_tag{
+  curl_mime            *mime;
+
+  int storage;
+  int err_mode;
+
+  lcurl_mime_part_t   *parts;
+  lcurl_mime_part_t   *parent; /*after set there no way change it*/
+}lcurl_mime_t;
+
+int lcurl_mime_create(lua_State *L, int error_mode);
+
+lcurl_mime_t *lcurl_getmime_at(lua_State *L, int i);
+
+#define lcurl_getmime(L) lcurl_getmime_at((L), 1)
+
+int lcurl_mime_part_create(lua_State *L, int error_mode);
+
+lcurl_mime_part_t *lcurl_getmimepart_at(lua_State *L, int i);
+
+#define lcurl_getmimepart(L) lcurl_getmimepart_at((L), 1)
+
+int lcurl_mime_set_lua(lua_State *L, lcurl_mime_t *p, lua_State *v);
+
+#endif
+
+#endif
\ No newline at end of file
diff --git a/src/lcopteasy.h b/src/lcopteasy.h
index 35725d1..d683d84 100644
--- a/src/lcopteasy.h
+++ b/src/lcopteasy.h
@@ -401,6 +401,10 @@ OPT_ENTRY( request_target,           REQUEST_TARGET,           STR, 0, LCURL_DEF
 OPT_ENTRY( socks5_auth,              SOCKS5_AUTH,              LNG, 0, LCURL_DEFAULT_VALUE)
 #endif
 
+#if LCURL_CURL_VER_GE(7,56,0)
+OPT_ENTRY( ssh_compression,          SSH_COMPRESSION,          LNG, 0, LCURL_DEFAULT_VALUE)
+#endif
+
 #ifdef LCURL__TCP_FASTOPEN
 #  define TCP_FASTOPEN LCURL__TCP_FASTOPEN
 #  undef LCURL__TCP_FASTOPEN
diff --git a/src/lcurl.c b/src/lcurl.c
index 512fe0c..c3d2c8f 100644
--- a/src/lcurl.c
+++ b/src/lcurl.c
@@ -14,6 +14,7 @@
 #include "lcshare.h"
 #include "lcerror.h"
 #include "lchttppost.h"
+#include "lcmime.h"
 #include "lcutils.h"
 
 /*export*/
@@ -113,6 +114,10 @@ static int lcurl_version_info(lua_State *L){
 #ifdef CURL_VERSION_HTTPS_PROXY
     lua_pushliteral(L, "HTTPS_PROXY");  lua_pushboolean(L, data->features & CURL_VERSION_HTTPS_PROXY ); lua_rawset(L, -3);
 #endif
+#ifdef CURL_VERSION_MULTI_SSL
+    lua_pushliteral(L, "MULTI_SSL");    lua_pushboolean(L, data->features & CURL_VERSION_MULTI_SSL   ); lua_rawset(L, -3);
+#endif
+
   lua_setfield(L, -2, "features");         /* bitmask, see defines below */
 
   if(data->ssl_version){lua_pushstring(L, data->ssl_version); lua_setfield(L, -2, "ssl_version");}      /* human readable string */
@@ -155,7 +160,7 @@ static const struct luaL_Reg lcurl_functions[] = {
   {"share",           lcurl_share_new        },
   {"version",         lcurl_version          },
   {"version_info",    lcurl_version_info     },
-
+  
   {NULL,NULL}
 };
 
@@ -215,6 +220,7 @@ static int luaopen_lcurl_(lua_State *L, const struct luaL_Reg *func){
   lua_pushvalue(L, -3); lua_pushvalue(L, -3); lcurl_error_initlib(L, 2);
   lua_pushvalue(L, -3); lua_pushvalue(L, -3); lcurl_hpost_initlib(L, 2);
   lua_pushvalue(L, -3); lua_pushvalue(L, -3); lcurl_easy_initlib (L, 2);
+  lua_pushvalue(L, -3); lua_pushvalue(L, -3); lcurl_mime_initlib (L, 2);
   lua_pushvalue(L, -3); lua_pushvalue(L, -3); lcurl_multi_initlib(L, 2);
   lua_pushvalue(L, -3); lua_pushvalue(L, -3); lcurl_share_initlib(L, 2);
 
diff --git a/src/lcutils.c b/src/lcutils.c
index c6baa6f..e4428fb 100644
--- a/src/lcutils.c
+++ b/src/lcutils.c
@@ -21,13 +21,21 @@ int lcurl_storage_init(lua_State *L){
 }
 
 void lcurl_storage_preserve_value(lua_State *L, int storage, int i){
-  assert(i > 0);
+  assert(i > 0 && i <= lua_gettop(L));
   luaL_checkany(L, i);
   lua_rawgeti(L, LCURL_LUA_REGISTRY, storage);
   lua_pushvalue(L, i); lua_pushboolean(L, 1); lua_rawset(L, -3);
   lua_pop(L, 1);
 }
 
+void lcurl_storage_remove_value(lua_State *L, int storage, int i){
+  assert(i > 0 && i <= lua_gettop(L));
+  luaL_checkany(L, i);
+  lua_rawgeti(L, LCURL_LUA_REGISTRY, storage);
+  lua_pushvalue(L, i); lua_pushnil(L); lua_rawset(L, -3);
+  lua_pop(L, 1);
+}
+
 static void lcurl_storage_ensure_t(lua_State *L, int t){
   lua_rawgeti(L, -1, t);
   if(!lua_istable(L, -1)){
@@ -256,7 +264,7 @@ int lcurl_utils_apply_options(lua_State *L, int opt, int obj, int do_close,
   while(lua_next(L, opt) != 0){
     int n;
     assert(lua_gettop(L) == (top + 2));
-    
+
     if(lua_type(L, -2) == LUA_TNUMBER){ /* [curl.OPT_URL] = "http://localhost" */
       lua_pushvalue(L, -2);
       lua_insert(L, -2);            /*Stack : opt, obj, k, k, v */
diff --git a/src/lcutils.h b/src/lcutils.h
index 25a822d..4a3e280 100644
--- a/src/lcutils.h
+++ b/src/lcutils.h
@@ -55,6 +55,8 @@ int lcurl_storage_init(lua_State *L);
 
 void lcurl_storage_preserve_value(lua_State *L, int storage, int i);
 
+void lcurl_storage_remove_value(lua_State *L, int storage, int i);
+
 int lcurl_storage_preserve_slist(lua_State *L, int storage, struct curl_slist * list);
 
 struct curl_slist* lcurl_storage_remove_slist(lua_State *L, int storage, int idx);
diff --git a/test/run.lua b/test/run.lua
index 44a694b..e5feee2 100644
--- a/test/run.lua
+++ b/test/run.lua
@@ -27,6 +27,7 @@ print("")
 require "test_safe"
 require "test_easy"
 require "test_form"
+require "test_mime"
 require "test_curl"
 
 RUN()
diff --git a/test/test_curl.lua b/test/test_curl.lua
index dbf4b25..3e65497 100644
--- a/test/test_curl.lua
+++ b/test/test_curl.lua
@@ -18,6 +18,12 @@ local scurl      = require "cURL.safe"
 local json       = require "dkjson"
 local fname      = "./test.download"
 
+local utils = require "utils"
+
+-- libcurl 7.56.0 does not add `Content-Type: text/plain`
+-- not sure is it bug or not
+local text_plain = utils.is_curl_eq(7,56,0) and 'test/plain' or 'text/plain'
+
 local ENABLE = true
 
 local _ENV = TEST_CASE'version'        if ENABLE then
@@ -222,11 +228,11 @@ function test_content_01()
 end
 
 function test_content_02()
-  post = assert(scurl.form{name02 = {'value02', type = "text/plain"}})
+  post = assert(scurl.form{name02 = {'value02', type = text_plain}})
   local data = assert_string(post:get())
   assert_match("\r\n\r\nvalue02\r\n", data)
   assert_match('name="name02"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_content_03()
@@ -238,12 +244,12 @@ function test_content_03()
 end
 
 function test_content_04()
-  post = assert(scurl.form{name04 = {'value04', type = "text/plain", headers = {"Content-Encoding: gzip"}}})
+  post = assert(scurl.form{name04 = {'value04', type = text_plain, headers = {"Content-Encoding: gzip"}}})
   local data = assert_string(post:get())
   assert_match("\r\n\r\nvalue04\r\n", data)
   assert_match('name="name04"', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_buffer_01()
@@ -263,14 +269,14 @@ function test_buffer_02()
   post = assert(scurl.form{name02 = {
     name = 'file02',
     data = 'value02',
-    type = "text/plain",
+    type = text_plain,
   }})
 
   local data = assert_string(post:get())
   assert_match("\r\n\r\nvalue02\r\n", data)
   assert_match('name="name02"', data)
   assert_match('filename="file02"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
   assert_not_match('Content%-Type: application/octet%-stream\r\n', data)
 end
 
@@ -292,7 +298,7 @@ function test_buffer_04()
   post = assert(scurl.form{name04 = {
     name = 'file04',
     data = 'value04',
-    type = "text/plain",
+    type = text_plain,
     headers = {"Content-Encoding: gzip"},
   }})
 
@@ -300,7 +306,7 @@ function test_buffer_04()
   assert_match("\r\n\r\nvalue04\r\n", data)
   assert_match('name="name04"', data)
   assert_match('filename="file04"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
   assert_not_match('Content%-Type: application/octet%-stream\r\n', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
 end
@@ -331,13 +337,13 @@ function test_stream_03()
     name   = 'file03',
     stream = function() end,
     length = 128,
-    type   = 'text/plain',
+    type   = text_plain,
   }})
 
   local data = assert_string(post:get())
   assert_match('name="name03"', data)
   assert_match('filename="file03"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_stream_04()
@@ -345,13 +351,13 @@ function test_stream_04()
     name   = 'file04',
     stream = function() end,
     length = 128,
-    type   = 'text/plain',
+    type   = text_plain,
     headers = {"Content-Encoding: gzip"},
   }})
   local data = assert_string(post:get())
   assert_match('name="name04"', data)
   assert_match('filename="file04"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
 end
 
diff --git a/test/test_easy.lua b/test/test_easy.lua
index 1b2c02e..d61d335 100644
--- a/test/test_easy.lua
+++ b/test/test_easy.lua
@@ -17,6 +17,7 @@ local scurl      = require "lcurl.safe"
 local json       = require "dkjson"
 local path       = require "path"
 local upath      = require "path".new('/')
+local utils      = require "utils"
 local url        = "http://example.com"
 local fname      = "./test.download"
 
@@ -26,66 +27,8 @@ local fname      = "./test.download"
 -- print("------------------------------------")
 -- print("")
 
-local function weak_ptr(val)
-  return setmetatable({value = val},{__mode = 'v'})
-end
-
-local function gc_collect()
-  collectgarbage("collect")
-  collectgarbage("collect")
-end
-
-local function cver(min, maj, pat)
-  return min * 2^16 + maj * 2^8 + pat
-end
-
-local function is_curl_ge(min, maj, pat)
-  assert(0x070908 == cver(7,9,8))
-  return curl.version_info('version_num') >= cver(min, maj, pat)
-end
-
-local function read_file(n)
-  local f, e = io.open(n, "r")
-  if not f then return nil, e end
-  local d, e = f:read("*all")
-  f:close()
-  return d, e
-end
-
-local function get_bin_by(str,n)
-  local pos = 1 - n
-  return function()
-    pos = pos + n
-    return (str:sub(pos,pos+n-1))
-  end
-end
-
-local function strem(ch, n, m)
-  return n, get_bin_by( (ch):rep(n), m)
-end
-
-local function Stream(ch, n, m)
-  local size, reader
-
-  local _stream = {}
-
-  function _stream:read(...)
-    _stream.called_ctx = self
-    _stream.called_co  = coroutine.running()
-    return reader(...)
-  end
-
-  function _stream:size()
-    return size
-  end
-
-  function _stream:reset()
-    size, reader = strem(ch, n, m)
-    return self
-  end
-
-  return _stream:reset()
-end
+local weak_ptr, gc_collect, is_curl_ge, read_file, stream, Stream =
+  utils.import('weak_ptr', 'gc_collect', 'is_curl_ge', 'read_file', 'stream', 'Stream')
 
 local ENABLE = true
 
@@ -499,7 +442,7 @@ function teardown()
 end
 
 function test()
-  assert_equal(f, f:add_stream('SSSSS', strem('X', 128, 13)))
+  assert_equal(f, f:add_stream('SSSSS', stream('X', 128, 13)))
   assert_equal(c, c:setopt_httppost(f))
 
   -- should be called only stream callback
diff --git a/test/test_form.lua b/test/test_form.lua
index 96da473..11ac8e8 100644
--- a/test/test_form.lua
+++ b/test/test_form.lua
@@ -12,6 +12,12 @@ end
 local TEST_CASE  = assert(lunit.TEST_CASE)
 local skip       = lunit.skip or function() end
 
+local utils = require "utils"
+
+-- libcurl 7.56.0 does not add `Content-Type: text/plain`
+-- not sure is it bug or not
+local text_plain = utils.is_curl_eq(7,56,0) and 'test/plain' or 'text/plain'
+
 local curl      = require "lcurl"
 
 local _ENV = TEST_CASE'add_content' do
@@ -42,11 +48,11 @@ function test_01()
 end
 
 function test_02()
-  assert_equal(post, post:add_content('name02', 'value02', "text/plain"))
+  assert_equal(post, post:add_content('name02', 'value02', text_plain))
   local data = assert_string(post:get())
   assert_match("\r\n\r\nvalue02\r\n", data)
   assert_match('name="name02"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_03()
@@ -58,12 +64,12 @@ function test_03()
 end
 
 function test_04()
-  assert_equal(post, post:add_content('name04', 'value04', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('name04', 'value04', text_plain, {"Content-Encoding: gzip"}))
   local data = assert_string(post:get())
   assert_match("\r\n\r\nvalue04\r\n", data)
   assert_match('name="name04"', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_error()
@@ -97,12 +103,12 @@ function test_01()
 end
 
 function test_02()
-  assert_equal(post, post:add_buffer('name02', 'file02', 'value02', "text/plain"))
+  assert_equal(post, post:add_buffer('name02', 'file02', 'value02', text_plain))
   local data = assert_string(post:get())
   assert_match("\r\n\r\nvalue02\r\n", data)
   assert_match('name="name02"', data)
   assert_match('filename="file02"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
   assert_not_match('Content%-Type: application/octet%-stream\r\n', data)
 end
 
@@ -117,12 +123,12 @@ function test_03()
 end
 
 function test_04()
-  assert_equal(post, post:add_buffer('name04', 'file04', 'value04', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_buffer('name04', 'file04', 'value04', text_plain, {"Content-Encoding: gzip"}))
   local data = assert_string(post:get())
   assert_match("\r\n\r\nvalue04\r\n", data)
   assert_match('name="name04"', data)
   assert_match('filename="file04"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
   assert_not_match('Content%-Type: application/octet%-stream\r\n', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
 end
@@ -180,19 +186,19 @@ function test_02()
 end
 
 function test_03()
-  assert_equal(post, post:add_stream('name03', 'file03', 'text/plain', stream()))
+  assert_equal(post, post:add_stream('name03', 'file03', text_plain, stream()))
   local data = assert_string(post:get())
   assert_match('name="name03"', data)
   assert_match('filename="file03"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_04()
-  assert_equal(post, post:add_stream('name04', 'file04', 'text/plain', {"Content-Encoding: gzip"}, stream()))
+  assert_equal(post, post:add_stream('name04', 'file04', text_plain, {"Content-Encoding: gzip"}, stream()))
   local data = assert_string(post:get())
   assert_match('name="name04"', data)
   assert_match('filename="file04"', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
 end
 
@@ -290,21 +296,21 @@ function test_01()
 end
 
 function test_02()
-  assert_equal(post, post:add_file('nameXX', form_path, 'text/plain'))
+  assert_equal(post, post:add_file('nameXX', form_path, text_plain))
   local data = assert_string(post:get())
   check_form(data)
   assert_match('filename="' .. form_file .. '"', data)
   assert_not_match('Content%-Type: application/octet%-stream\r\n', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_03()
-  assert_equal(post, post:add_file('nameXX', form_path, 'text/plain', 'renamedfile'))
+  assert_equal(post, post:add_file('nameXX', form_path, text_plain, 'renamedfile'))
   local data = assert_string(post:get())
   check_form(data)
   assert_match('filename="' .. 'renamedfile' .. '"', data)
   assert_not_match('Content%-Type: application/octet%-stream\r\n', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_04()
@@ -316,22 +322,22 @@ function test_04()
 end
 
 function test_05()
-  assert_equal(post, post:add_file('nameXX', form_path, 'text/plain', 'renamedfile', {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_file('nameXX', form_path, text_plain, 'renamedfile', {"Content-Encoding: gzip"}))
   local data = assert_string(post:get())
   check_form(data)
   assert_match('filename="' .. 'renamedfile' .. '"', data)
   assert_not_match('Content%-Type: application/octet%-stream\r\n', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
 end
 
 function test_05()
-  assert_equal(post, post:add_file('nameXX', form_path, 'text/plain', {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_file('nameXX', form_path, text_plain, {"Content-Encoding: gzip"}))
   local data = assert_string(post:get())
   check_form(data)
   assert_match('filename="' .. form_file .. '"', data)
   assert_not_match('Content%-Type: application/octet%-stream\r\n', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
 end
 
@@ -364,7 +370,7 @@ end
 
 function test_error()
   assert_error(function()
-    assert_equal(post, post:add_file('nameXX', 'text/plain', form_path))
+    assert_equal(post, post:add_file('nameXX', text_plain, form_path))
     post:get()
   end)
 end
@@ -388,7 +394,7 @@ local function check_form(data)
   assert_match("\r\n\r\nvalueXX\r\n", data)
   assert_match('name="nameXX"', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_writer_01()
@@ -397,7 +403,7 @@ function test_writer_01()
     assert_equal(0, select("#", ...))
     t[#t+1] = str
   end
-  assert_equal(post, post:add_content('nameXX', 'valueXX', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('nameXX', 'valueXX', text_plain, {"Content-Encoding: gzip"}))
   assert_equal(post, post:get(writer))
   check_form(table.concat(t))
 end
@@ -409,7 +415,7 @@ function test_writer_02()
     t[#t+1] = str
     return true
   end
-  assert_equal(post, post:add_content('nameXX', 'valueXX', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('nameXX', 'valueXX', text_plain, {"Content-Encoding: gzip"}))
   assert_equal(post, post:get(writer))
   check_form(table.concat(t))
 end
@@ -421,7 +427,7 @@ function test_writer_03()
     t[#t+1] = str
     return #str
   end
-  assert_equal(post, post:add_content('nameXX', 'valueXX', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('nameXX', 'valueXX', text_plain, {"Content-Encoding: gzip"}))
   assert_equal(post, post:get(writer))
   check_form(table.concat(t))
 end
@@ -433,40 +439,40 @@ function test_writer_context()
     assert_equal(0, select("#", ...))
     T[#T+1] = str
   end
-  assert_equal(post, post:add_content('nameXX', 'valueXX', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('nameXX', 'valueXX', text_plain, {"Content-Encoding: gzip"}))
   assert_equal(post, post:get(writer, t))
   local data = table.concat(t)
   assert_match("\r\n\r\nvalueXX\r\n", data)
   assert_match('name="nameXX"', data)
   assert_match('Content%-Encoding: gzip\r\n', data)
-  assert_match('Content%-Type: text/plain\r\n', data)
+  assert_match('Content%-Type: ' .. text_plain .. '\r\n', data)
 end
 
 function test_abort_01()
   local err = {}
   local function writer() return nil, err end
-  assert_equal(post, post:add_content('nameXX', 'valueXX', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('nameXX', 'valueXX', text_plain, {"Content-Encoding: gzip"}))
   local _, e = assert_nil(post:get(writer))
   assert_equal(err, e)
 end
 
 function test_abort_02()
   local function writer() return 0 end
-  assert_equal(post, post:add_content('nameXX', 'valueXX', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('nameXX', 'valueXX', text_plain, {"Content-Encoding: gzip"}))
   local _, e = assert_nil(post:get(writer))
   assert_nil(e)
 end
 
 function test_abort_03()
   local function writer() return nil end
-  assert_equal(post, post:add_content('nameXX', 'valueXX', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('nameXX', 'valueXX', text_plain, {"Content-Encoding: gzip"}))
   local _, e = assert_nil(post:get(writer))
   assert_nil(e)
 end
 
 function test_abort_04()
   local function writer() return false end
-  assert_equal(post, post:add_content('nameXX', 'valueXX', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('nameXX', 'valueXX', text_plain, {"Content-Encoding: gzip"}))
   local _, e = assert_nil(post:get(writer))
   assert_nil(e)
 end
@@ -474,7 +480,7 @@ end
 function test_error()
   local err = {}
   local function writer() error("WRITEERROR") end
-  assert_equal(post, post:add_content('nameXX', 'valueXX', "text/plain", {"Content-Encoding: gzip"}))
+  assert_equal(post, post:add_content('nameXX', 'valueXX', text_plain, {"Content-Encoding: gzip"}))
   assert_error_match("WRITEERROR", function()
     post:get(writer)
   end)
diff --git a/test/test_mime.lua b/test/test_mime.lua
new file mode 100644
index 0000000..602297c
--- /dev/null
+++ b/test/test_mime.lua
@@ -0,0 +1,188 @@
+local lunit, RUN = lunit do
+RUN   = lunit and function()end or function ()
+  local res = lunit.run()
+  if res.errors + res.failed > 0 then
+    os.exit(-1)
+  end
+  return os.exit(0)
+end
+lunit = require "lunit"
+end
+
+local TEST_CASE  = assert(lunit.TEST_CASE)
+local skip       = lunit.skip or function() end
+
+local curl      = require "lcurl"
+
+local function weak_ptr(val)
+  return setmetatable({value = val}, {__mode = 'v'})
+end
+
+local function gc_collect(n)
+  for i = 1, (n or 10) do
+    collectgarbage("collect")
+  end
+end
+
+local function is_freed(c)
+  return not not string.find(tostring(c), '%(freed%)')
+end
+
+local _ENV = TEST_CASE'mime lifetime' if not curl.OPT_MIMEPOST then
+function test() skip("MIMI API supports since cURL 7.56.0") end
+else
+
+local easy, mime
+
+function setup()
+  easy = curl.easy()
+end
+
+function teardown()
+  if easy then easy:close() end
+  if mime then mime:free() end
+  easy, mime = nil
+end
+
+function test_preserve_mime_part_reference()
+  -- mime part stores references to all parts
+
+  local mime, part = easy:mime() do
+    part = weak_ptr(mime:addpart())
+  end
+  gc_collect()
+
+  assert_not_nil(part.value)
+
+  mime = nil
+  gc_collect()
+
+  assert_nil(part.value)
+
+  easy:close()
+end
+
+function test_free_mime_subparts()
+  -- when free root free all nodes
+
+  -- mime
+  --  +- part3
+  --      +- alt
+  --          +- part1
+  --          +- part2
+
+  local mime, a, p1, p2, p3 = easy:mime() do
+
+    local alt = easy:mime()
+
+    local part1 = alt:addpart()
+
+    local part2 = alt:addpart()
+
+    local part3 = mime:addpart()
+    part3:subparts(alt, "multipart/alternative")
+
+    a  = weak_ptr(alt)
+    p1 = weak_ptr(part1)
+    p2 = weak_ptr(part2)
+    p3 = weak_ptr(part3)
+  end
+
+  gc_collect()
+
+  assert_not_nil(a.value)
+  assert_not_nil(p1.value)
+  assert_not_nil(p2.value)
+  assert_not_nil(p3.value)
+
+  -- reamove reference to root node
+  mime = nil
+  gc_collect(4)
+
+  assert_nil(a.value)
+  assert_nil(p1.value)
+  assert_nil(p2.value)
+  assert_nil(p3.value)
+
+  easy:close()
+end
+
+function test_preserve_mime_subparts()
+  -- if we have references to subnode but we free root
+  -- then all references have to become to invalid
+
+  -- mime
+  --  +- part3
+  --      +- alt
+  --          +- part1
+  --          +- part2
+
+  local easy = curl.easy()
+
+  local mime, a, p1, p2, p3 = easy:mime() do
+
+    local alt = easy:mime()
+
+    local part1 = alt:addpart()
+
+    local part2 = alt:addpart()
+
+    local part3 = mime:addpart()
+    part3:subparts(alt, "multipart/alternative")
+
+    a  = weak_ptr(alt)
+    p1 = weak_ptr(part1)
+    p2 = weak_ptr(part2)
+    p3 = weak_ptr(part3)
+  end
+
+  gc_collect()
+
+  assert_not_nil(a.value)
+  assert_not_nil(p1.value)
+  assert_not_nil(p2.value)
+  assert_not_nil(p3.value)
+
+  -- save reference to subnode
+  local subnode = a.value
+
+  mime = nil
+
+  -- in this case call `free` to root node.
+  -- there no way to get reference to this node from child
+  -- so there no way to use it.
+  gc_collect()
+
+  -- libcurl still close all childs
+  -- so all reference are invalid
+
+  assert_not_nil(a.value)
+  assert_not_nil(is_freed(a.value))
+  assert_nil(p1.value)
+  assert_nil(p2.value)
+  assert_nil(p3.value)
+
+  easy:close()
+end
+
+function test_preserve_mime_by_easy()
+
+  local mime do
+    mime = weak_ptr(easy:mime())
+    easy:setopt_mimepost(mime.value)
+  end
+
+  gc_collect()
+
+  assert_not_nil(mime.value)
+
+  easy:unsetopt_mimepost()
+
+  gc_collect()
+
+  assert_nil(mime.value)
+end
+
+end
+
+RUN()
diff --git a/test/utils.lua b/test/utils.lua
new file mode 100644
index 0000000..798a105
--- /dev/null
+++ b/test/utils.lua
@@ -0,0 +1,89 @@
+local curl = require "lcurl"
+
+local function weak_ptr(val)
+  return setmetatable({value = val},{__mode = 'v'})
+end
+
+local function gc_collect()
+  collectgarbage("collect")
+  collectgarbage("collect")
+end
+
+local function cver(min, maj, pat)
+  return min * 2^16 + maj * 2^8 + pat
+end
+
+local function is_curl_ge(min, maj, pat)
+  assert(0x070908 == cver(7,9,8))
+  return curl.version_info('version_num') >= cver(min, maj, pat)
+end
+
+local function is_curl_eq(min, maj, pat)
+  assert(0x070908 == cver(7,9,8))
+  return curl.version_info('version_num') == cver(min, maj, pat)
+end
+
+local function read_file(n)
+  local f, e = io.open(n, "r")
+  if not f then return nil, e end
+  local d, e = f:read("*all")
+  f:close()
+  return d, e
+end
+
+local function get_bin_by(str,n)
+  local pos = 1 - n
+  return function()
+    pos = pos + n
+    return (str:sub(pos,pos+n-1))
+  end
+end
+
+local function stream(ch, n, m)
+  return n, get_bin_by( (ch):rep(n), m)
+end
+
+local function Stream(ch, n, m)
+  local size, reader
+
+  local _stream = {}
+
+  function _stream:read(...)
+    _stream.called_ctx = self
+    _stream.called_co  = coroutine.running()
+    return reader(...)
+  end
+
+  function _stream:size()
+    return size
+  end
+
+  function _stream:reset()
+    size, reader = stream(ch, n, m)
+    return self
+  end
+
+  return _stream:reset()
+end
+
+local utils = {
+  weak_ptr   = weak_ptr;
+  gc_collect = gc_collect;
+  is_curl_ge = is_curl_ge;
+  is_curl_eq = is_curl_eq;
+  get_bin_by = get_bin_by;
+  read_file  = read_file;
+  stream     = stream;
+  Stream     = Stream;
+}
+
+utils.import = function(...)
+  local n, t = select('#', ...), {}
+  for i = 1, n do
+    local name = select(i, ...)
+    t[#t + 1] = assert(utils[name], 'unknown field: ' .. tostring(name))
+  end
+  return (unpack or table.unpack)(t, 1, n)
+end
+
+return utils
\ No newline at end of file