curl_easy_reset: release mime-related data.

Move curl_mime_initpart() and curl_mime_cleanpart() calls to lower-level
functions dealing with UserDefined structure contents.
This avoids memory leakages on curl-generated part mime headers.
New test 2073 checks this using the cli tool --next option: it
triggers a valgrind error if bug is present.

Bug: https://curl.haxx.se/mail/lib-2017-12/0060.html
Reported-by: Martin Galvan

lib/easy.c

@@ -998,7 +998,7 @@ void curl_easy_reset(struct Curl_easy *data)
   /* zero out UserDefined data: */
   Curl_freeset(data);
   memset(&data->set, 0, sizeof(struct UserDefined));
-  (void)Curl_init_userdefined(&data->set);
+  (void)Curl_init_userdefined(data);
 
   /* zero out Progress data: */
   memset(&data->progress, 0, sizeof(struct Progress));

lib/url.c

@@ -293,6 +293,8 @@ void Curl_freeset(struct Curl_easy *data)
     data->change.url_alloc = FALSE;
   }
   data->change.url = NULL;
+
+  Curl_mime_cleanpart(&data->set.mimepost);
 }
 
 /*
@@ -382,8 +384,6 @@ CURLcode Curl_close(struct Curl_easy *data)
   Curl_http2_cleanup_dependencies(data);
   Curl_convert_close(data);
 
-  Curl_mime_cleanpart(&data->set.mimepost);
-
   /* No longer a dirty share, if it exists */
   if(data->share) {
     Curl_share_lock(data, CURL_LOCK_DATA_SHARE, CURL_LOCK_ACCESS_SINGLE);
@@ -402,8 +402,9 @@ CURLcode Curl_close(struct Curl_easy *data)
  * Initialize the UserDefined fields within a Curl_easy.
  * This may be safely called on a new or existing Curl_easy.
  */
-CURLcode Curl_init_userdefined(struct UserDefined *set)
+CURLcode Curl_init_userdefined(struct Curl_easy *data)
 {
+  struct UserDefined *set = &data->set;
   CURLcode result = CURLE_OK;
 
   set->out = stdout; /* default output to stdout */
@@ -453,6 +454,8 @@ CURLcode Curl_init_userdefined(struct UserDefined *set)
   /* make libcurl quiet by default: */
   set->hide_progress = TRUE;  /* CURLOPT_NOPROGRESS changes these */
 
+  Curl_mime_initpart(&set->mimepost, data);
+
   /*
    * libcurl 7.10 introduced SSL verification *by default*! This needs to be
    * switched off unless wanted.
@@ -569,15 +572,13 @@ CURLcode Curl_open(struct Curl_easy **curl)
     result = CURLE_OUT_OF_MEMORY;
   }
   else {
-    Curl_mime_initpart(&data->set.mimepost, data);
-
     data->state.headerbuff = malloc(HEADERSIZE);
     if(!data->state.headerbuff) {
       DEBUGF(fprintf(stderr, "Error: malloc of headerbuff failed\n"));
       result = CURLE_OUT_OF_MEMORY;
     }
     else {
-      result = Curl_init_userdefined(&data->set);
+      result = Curl_init_userdefined(data);
 
       data->state.headersize = HEADERSIZE;
       Curl_convert_init(data);

lib/url.h

@@ -33,7 +33,7 @@
 
 CURLcode Curl_init_do(struct Curl_easy *data, struct connectdata *conn);
 CURLcode Curl_open(struct Curl_easy **curl);
-CURLcode Curl_init_userdefined(struct UserDefined *set);
+CURLcode Curl_init_userdefined(struct Curl_easy *data);
 CURLcode Curl_setopt(struct Curl_easy *data, CURLoption option,
                      va_list arg);
 CURLcode Curl_dupset(struct Curl_easy * dst, struct Curl_easy * src);

tests/data/Makefile.inc

@@ -189,4 +189,4 @@ test2048 test2049 test2050 test2051 test2052 test2053 test2054 test2055 \
 test2056 test2057 test2058 test2059 test2060 test2061 test2062 test2063 \
 test2064 test2065 test2066 test2067 test2068 test2069 \
 \
-test2070 test2071 test2072
+test2070 test2071 test2072 test2073

tests/data/test2073

@@ -0,0 +1,68 @@
+<testcase>
+<info>
+<keywords>
+HTTP
+HTTP FORMPOST
+</keywords>
+</info>
+#
+# Server-side
+<reply>
+<data>
+HTTP/1.1 200 OK
+Date: Thu, 09 Nov 2010 14:49:00 GMT
+Content-Length: 10
+
+contents1
+</data>
+<data1>
+HTTP/1.1 200 OK
+Date: Thu, 09 Nov 2010 14:49:00 GMT
+Content-Length: 10
+
+contents2
+</data1>
+</reply>
+
+#
+# Client-side
+<client>
+<server>
+http
+</server>
+ <name>
+HTTP form posts with handle reset
+ </name>
+ <command>
+http://%HOSTIP:%HTTPPORT/2073 -F 'name=a;filename=a.pdf' --next http://%HOSTIP:%HTTPPORT/2073 -F 'name=b;filename=b.jpg'
+</command>
+</client>
+
+#
+# Verify data after the test has been "shot"
+<verify>
+<strip>
+^(User-Agent:|Content-Type: multipart/form-data;|------------).*
+</strip>
+<protocol>
+POST /2073 HTTP/1.1
+Host: %HOSTIP:%HTTPPORT
+Accept: */*
+Content-Length: 189
+
+Content-Disposition: form-data; name="name"; filename="a.pdf"
+Content-Type: application/pdf
+
+a
+POST /2073 HTTP/1.1
+Host: %HOSTIP:%HTTPPORT
+Accept: */*
+Content-Length: 184
+
+Content-Disposition: form-data; name="name"; filename="b.jpg"
+Content-Type: image/jpeg
+
+b
+</protocol>
+</verify>
+</testcase>