URL-API

See header file and man pages for API. All documented API details work
and are tested in the 1560 test case.

Closes #2842

9 files changed, 1394 insertions, 340 deletions

diff --git a/lib/Makefile.inc b/lib/Makefile.inc
index ac0affeae..83a27dd0b 100644
--- a/lib/Makefile.inc
+++ b/lib/Makefile.inc
@@ -55,7 +55,7 @@ LIB_CFILES = file.c timeval.c base64.c hostip.c progress.c formdata.c   \
   curl_multibyte.c hostcheck.c conncache.c pipeline.c dotdot.c          \
   x509asn1.c http2.c smb.c curl_endian.c curl_des.c system_win32.c      \
   mime.c sha256.c setopt.c curl_path.c curl_ctype.c curl_range.c psl.c  \
-  doh.c
+  doh.c urlapi.c
 
 LIB_HFILES = arpa_telnet.h netrc.h file.h timeval.h hostip.h progress.h \
   formdata.h cookie.h http.h sendf.h ftp.h url.h dict.h if2ip.h         \
@@ -75,7 +75,7 @@ LIB_HFILES = arpa_telnet.h netrc.h file.h timeval.h hostip.h progress.h \
   curl_setup_once.h multihandle.h setup-vms.h pipeline.h dotdot.h       \
   x509asn1.h http2.h sigpipe.h smb.h curl_endian.h curl_des.h           \
   curl_printf.h system_win32.h rand.h mime.h curl_sha256.h setopt.h     \
-  curl_path.h curl_ctype.h curl_range.h psl.h doh.h
+  curl_path.h curl_ctype.h curl_range.h psl.h doh.h urlapi-int.h
 
 LIB_RCFILES = libcurl.rc
 
diff --git a/lib/escape.c b/lib/escape.c
index 10774f058..afd3899f9 100644
--- a/lib/escape.c
+++ b/lib/escape.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2018, 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
@@ -41,7 +41,7 @@
    its behavior is altered by the current locale.
    See https://tools.ietf.org/html/rfc3986#section-2.3
 */
-static bool Curl_isunreserved(unsigned char in)
+bool Curl_isunreserved(unsigned char in)
 {
   switch(in) {
     case '0': case '1': case '2': case '3': case '4':
@@ -141,6 +141,8 @@ char *curl_easy_escape(struct Curl_easy *data, const char *string,
  * Returns a pointer to a malloced string in *ostring with length given in
  * *olen. If length == 0, the length is assumed to be strlen(string).
  *
+ * 'data' can be set to NULL but then this function can't convert network
+ * data to host for non-ascii.
  */
 CURLcode Curl_urldecode(struct Curl_easy *data,
                         const char *string, size_t length,
@@ -151,7 +153,7 @@ CURLcode Curl_urldecode(struct Curl_easy *data,
   char *ns = malloc(alloc);
   size_t strindex = 0;
   unsigned long hex;
-  CURLcode result;
+  CURLcode result = CURLE_OK;
 
   if(!ns)
     return CURLE_OUT_OF_MEMORY;
@@ -171,11 +173,13 @@ CURLcode Curl_urldecode(struct Curl_easy *data,
 
       in = curlx_ultouc(hex); /* this long is never bigger than 255 anyway */
 
-      result = Curl_convert_from_network(data, (char *)&in, 1);
-      if(result) {
-        /* Curl_convert_from_network calls failf if unsuccessful */
-        free(ns);
-        return result;
+      if(data) {
+        result = Curl_convert_from_network(data, (char *)&in, 1);
+        if(result) {
+          /* Curl_convert_from_network calls failf if unsuccessful */
+          free(ns);
+          return result;
+        }
       }
 
       string += 2;
diff --git a/lib/escape.h b/lib/escape.h
index 638666f03..666f1ad71 100644
--- a/lib/escape.h
+++ b/lib/escape.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2018, 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
@@ -24,6 +24,7 @@
 /* Escape and unescape URL encoding in strings. The functions return a new
  * allocated string or NULL if an error occurred.  */
 
+bool Curl_isunreserved(unsigned char in);
 CURLcode Curl_urldecode(struct Curl_easy *data,
                         const char *string, size_t length,
                         char **ostring, size_t *olen,
diff --git a/lib/imap.c b/lib/imap.c
index 4a9c01ae7..63fcb4d41 100644
--- a/lib/imap.c
+++ b/lib/imap.c
@@ -159,7 +159,8 @@ const struct Curl_handler Curl_handler_imaps = {
   ZERO_NULL,                        /* connection_check */
   PORT_IMAPS,                       /* defport */
   CURLPROTO_IMAPS,                  /* protocol */
-  PROTOPT_CLOSEACTION | PROTOPT_SSL /* flags */
+  PROTOPT_CLOSEACTION | PROTOPT_SSL | /* flags */
+  PROTOPT_URLOPTIONS
 };
 #endif
 
diff --git a/lib/transfer.c b/lib/transfer.c
index 63d01efd9..3d8089ee6 100644
--- a/lib/transfer.c
+++ b/lib/transfer.c
@@ -75,6 +75,7 @@
 #include "http2.h"
 #include "mime.h"
 #include "strcase.h"
+#include "urlapi-int.h"
 
 /* The last 3 #include files should be in this order */
 #include "curl_printf.h"
@@ -1454,311 +1455,6 @@ CURLcode Curl_posttransfer(struct Curl_easy *data)
   return CURLE_OK;
 }
 
-#ifndef CURL_DISABLE_HTTP
-/*
- * Find the separator at the end of the host name, or the '?' in cases like
- * http://www.url.com?id=2380
- */
-static const char *find_host_sep(const char *url)
-{
-  const char *sep;
-  const char *query;
-
-  /* Find the start of the hostname */
-  sep = strstr(url, "//");
-  if(!sep)
-    sep = url;
-  else
-    sep += 2;
-
-  query = strchr(sep, '?');
-  sep = strchr(sep, '/');
-
-  if(!sep)
-    sep = url + strlen(url);
-
-  if(!query)
-    query = url + strlen(url);
-
-  return sep < query ? sep : query;
-}
-
-/*
- * Decide in an encoding-independent manner whether a character in an
- * URL must be escaped. The same criterion must be used in strlen_url()
- * and strcpy_url().
- */
-static bool urlchar_needs_escaping(int c)
-{
-    return !(ISCNTRL(c) || ISSPACE(c) || ISGRAPH(c));
-}
-
-/*
- * strlen_url() returns the length of the given URL if the spaces within the
- * URL were properly URL encoded.
- * URL encoding should be skipped for host names, otherwise IDN resolution
- * will fail.
- */
-static size_t strlen_url(const char *url, bool relative)
-{
-  const unsigned char *ptr;
-  size_t newlen = 0;
-  bool left = TRUE; /* left side of the ? */
-  const unsigned char *host_sep = (const unsigned char *) url;
-
-  if(!relative)
-    host_sep = (const unsigned char *) find_host_sep(url);
-
-  for(ptr = (unsigned char *)url; *ptr; ptr++) {
-
-    if(ptr < host_sep) {
-      ++newlen;
-      continue;
-    }
-
-    switch(*ptr) {
-    case '?':
-      left = FALSE;
-      /* FALLTHROUGH */
-    default:
-      if(urlchar_needs_escaping(*ptr))
-        newlen += 2;
-      newlen++;
-      break;
-    case ' ':
-      if(left)
-        newlen += 3;
-      else
-        newlen++;
-      break;
-    }
-  }
-  return newlen;
-}
-
-/* strcpy_url() copies a url to a output buffer and URL-encodes the spaces in
- * the source URL accordingly.
- * URL encoding should be skipped for host names, otherwise IDN resolution
- * will fail.
- */
-static void strcpy_url(char *output, const char *url, bool relative)
-{
-  /* we must add this with whitespace-replacing */
-  bool left = TRUE;
-  const unsigned char *iptr;
-  char *optr = output;
-  const unsigned char *host_sep = (const unsigned char *) url;
-
-  if(!relative)
-    host_sep = (const unsigned char *) find_host_sep(url);
-
-  for(iptr = (unsigned char *)url;    /* read from here */
-      *iptr;         /* until zero byte */
-      iptr++) {
-
-    if(iptr < host_sep) {
-      *optr++ = *iptr;
-      continue;
-    }
-
-    switch(*iptr) {
-    case '?':
-      left = FALSE;
-      /* FALLTHROUGH */
-    default:
-      if(urlchar_needs_escaping(*iptr)) {
-        snprintf(optr, 4, "%%%02x", *iptr);
-        optr += 3;
-      }
-      else
-        *optr++=*iptr;
-      break;
-    case ' ':
-      if(left) {
-        *optr++='%'; /* add a '%' */
-        *optr++='2'; /* add a '2' */
-        *optr++='0'; /* add a '0' */
-      }
-      else
-        *optr++='+'; /* add a '+' here */
-      break;
-    }
-  }
-  *optr = 0; /* zero terminate output buffer */
-
-}
-
-/*
- * Returns true if the given URL is absolute (as opposed to relative)
- */
-static bool is_absolute_url(const char *url)
-{
-  char prot[16]; /* URL protocol string storage */
-  char letter;   /* used for a silly sscanf */
-
-  return (2 == sscanf(url, "%15[^?&/:]://%c", prot, &letter)) ? TRUE : FALSE;
-}
-
-/*
- * Concatenate a relative URL to a base URL making it absolute.
- * URL-encodes any spaces.
- * The returned pointer must be freed by the caller unless NULL
- * (returns NULL on out of memory).
- */
-static char *concat_url(const char *base, const char *relurl)
-{
-  /***
-   TRY to append this new path to the old URL
-   to the right of the host part. Oh crap, this is doomed to cause
-   problems in the future...
-  */
-  char *newest;
-  char *protsep;
-  char *pathsep;
-  size_t newlen;
-  bool host_changed = FALSE;
-
-  const char *useurl = relurl;
-  size_t urllen;
-
-  /* we must make our own copy of the URL to play with, as it may
-     point to read-only data */
-  char *url_clone = strdup(base);
-
-  if(!url_clone)
-    return NULL; /* skip out of this NOW */
-
-  /* protsep points to the start of the host name */
-  protsep = strstr(url_clone, "//");
-  if(!protsep)
-    protsep = url_clone;
-  else
-    protsep += 2; /* pass the slashes */
-
-  if('/' != relurl[0]) {
-    int level = 0;
-
-    /* First we need to find out if there's a ?-letter in the URL,
-       and cut it and the right-side of that off */
-    pathsep = strchr(protsep, '?');
-    if(pathsep)
-      *pathsep = 0;
-
-    /* we have a relative path to append to the last slash if there's one
-       available, or if the new URL is just a query string (starts with a
-       '?')  we append the new one at the end of the entire currently worked
-       out URL */
-    if(useurl[0] != '?') {
-      pathsep = strrchr(protsep, '/');
-      if(pathsep)
-        *pathsep = 0;
-    }
-
-    /* Check if there's any slash after the host name, and if so, remember
-       that position instead */
-    pathsep = strchr(protsep, '/');
-    if(pathsep)
-      protsep = pathsep + 1;
-    else
-      protsep = NULL;
-
-    /* now deal with one "./" or any amount of "../" in the newurl
-       and act accordingly */
-
-    if((useurl[0] == '.') && (useurl[1] == '/'))
-      useurl += 2; /* just skip the "./" */
-
-    while((useurl[0] == '.') &&
-          (useurl[1] == '.') &&
-          (useurl[2] == '/')) {
-      level++;
-      useurl += 3; /* pass the "../" */
-    }
-
-    if(protsep) {
-      while(level--) {
-        /* cut off one more level from the right of the original URL */
-        pathsep = strrchr(protsep, '/');
-        if(pathsep)
-          *pathsep = 0;
-        else {
-          *protsep = 0;
-          break;
-        }
-      }
-    }
-  }
-  else {
-    /* We got a new absolute path for this server */
-
-    if((relurl[0] == '/') && (relurl[1] == '/')) {
-      /* the new URL starts with //, just keep the protocol part from the
-         original one */
-      *protsep = 0;
-      useurl = &relurl[2]; /* we keep the slashes from the original, so we
-                              skip the new ones */
-      host_changed = TRUE;
-    }
-    else {
-      /* cut off the original URL from the first slash, or deal with URLs
-         without slash */
-      pathsep = strchr(protsep, '/');
-      if(pathsep) {
-        /* When people use badly formatted URLs, such as
-           "http://www.url.com?dir=/home/daniel" we must not use the first
-           slash, if there's a ?-letter before it! */
-        char *sep = strchr(protsep, '?');
-        if(sep && (sep < pathsep))
-          pathsep = sep;
-        *pathsep = 0;
-      }
-      else {
-        /* There was no slash. Now, since we might be operating on a badly
-           formatted URL, such as "http://www.url.com?id=2380" which doesn't
-           use a slash separator as it is supposed to, we need to check for a
-           ?-letter as well! */
-        pathsep = strchr(protsep, '?');
-        if(pathsep)
-          *pathsep = 0;
-      }
-    }
-  }
-
-  /* If the new part contains a space, this is a mighty stupid redirect
-     but we still make an effort to do "right". To the left of a '?'
-     letter we replace each space with %20 while it is replaced with '+'
-     on the right side of the '?' letter.
-  */
-  newlen = strlen_url(useurl, !host_changed);
-
-  urllen = strlen(url_clone);
-
-  newest = malloc(urllen + 1 + /* possible slash */
-                  newlen + 1 /* zero byte */);
-
-  if(!newest) {
-    free(url_clone); /* don't leak this */
-    return NULL;
-  }
-
-  /* copy over the root url part */
-  memcpy(newest, url_clone, urllen);
-
-  /* check if we need to append a slash */
-  if(('/' == useurl[0]) || (protsep && !*protsep) || ('?' == useurl[0]))
-    ;
-  else
-    newest[urllen++]='/';
-
-  /* then append the new piece on the right side */
-  strcpy_url(&newest[urllen], useurl, !host_changed);
-
-  free(url_clone);
-
-  return newest;
-}
-#endif /* CURL_DISABLE_HTTP */
-
 /*
  * Curl_follow() handles the URL redirect magic. Pass in the 'newurl' string
  * as given by the remote server and set up the new URL to request.
@@ -1810,12 +1506,12 @@ CURLcode Curl_follow(struct Curl_easy *data,
     }
   }
 
-  if(!is_absolute_url(newurl)) {
+  if(!Curl_is_absolute_url(newurl, NULL, 8)) {
     /***
      *DANG* this is an RFC 2068 violation. The URL is supposed
      to be absolute and this doesn't seem to be that!
      */
-    char *absolute = concat_url(data->change.url, newurl);
+    char *absolute = Curl_concat_url(data->change.url, newurl);
     if(!absolute)
       return CURLE_OUT_OF_MEMORY;
     newurl = absolute;
@@ -1824,7 +1520,7 @@ CURLcode Curl_follow(struct Curl_easy *data,
     /* The new URL MAY contain space or high byte values, that means a mighty
        stupid redirect URL but we still make an effort to do "right". */
     char *newest;
-    size_t newlen = strlen_url(newurl, FALSE);
+    size_t newlen = Curl_strlen_url(newurl, FALSE);
 
     /* This is an absolute URL, don't allow the custom port number */
     disallowport = TRUE;
@@ -1833,7 +1529,7 @@ CURLcode Curl_follow(struct Curl_easy *data,
     if(!newest)
       return CURLE_OUT_OF_MEMORY;
 
-    strcpy_url(newest, newurl, FALSE); /* create a space-free URL */
+    Curl_strcpy_url(newest, newurl, FALSE); /* create a space-free URL */
     newurl = newest; /* use this instead now */
 
   }
diff --git a/lib/url.c b/lib/url.c
index 977f1d6ad..66faa400d 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -1944,30 +1944,37 @@ static struct connectdata *allocate_conn(struct Curl_easy *data)
   return NULL;
 }
 
-static CURLcode findprotocol(struct Curl_easy *data,
-                             struct connectdata *conn,
-                             const char *protostr)
+/* returns the handdler if the given scheme is built-in */
+const struct Curl_handler *Curl_builtin_scheme(const char *scheme)
 {
   const struct Curl_handler * const *pp;
   const struct Curl_handler *p;
-
-  /* Scan protocol handler table and match against 'protostr' to set a few
-     variables based on the URL. Now that the handler may be changed later
-     when the protocol specific setup function is called. */
-  for(pp = protocols; (p = *pp) != NULL; pp++) {
-    if(strcasecompare(p->scheme, protostr)) {
+  /* Scan protocol handler table and match against 'scheme'. The handler may
+     be changed later when the protocol specific setup function is called. */
+  for(pp = protocols; (p = *pp) != NULL; pp++)
+    if(strcasecompare(p->scheme, scheme))
       /* Protocol found in table. Check if allowed */
-      if(!(data->set.allowed_protocols & p->protocol))
-        /* nope, get out */
-        break;
+      return p;
+  return NULL; /* not found */
+}
 
-      /* it is allowed for "normal" request, now do an extra check if this is
-         the result of a redirect */
-      if(data->state.this_is_a_follow &&
-         !(data->set.redir_protocols & p->protocol))
-        /* nope, get out */
-        break;
 
+static CURLcode findprotocol(struct Curl_easy *data,
+                             struct connectdata *conn,
+                             const char *protostr)
+{
+  const struct Curl_handler *p = Curl_builtin_scheme(protostr);
+
+  if(p && /* Protocol found in table. Check if allowed */
+     (data->set.allowed_protocols & p->protocol)) {
+
+    /* it is allowed for "normal" request, now do an extra check if this is
+       the result of a redirect */
+    if(data->state.this_is_a_follow &&
+       !(data->set.redir_protocols & p->protocol))
+      /* nope, get out */
+      ;
+    else {
       /* Perform setup complement if some. */
       conn->handler = conn->given = p;
 
@@ -1976,7 +1983,6 @@ static CURLcode findprotocol(struct Curl_easy *data,
     }
   }
 
-
   /* The protocol was not found in the table, but we don't have to assign it
      to anything since it is already assigned to a dummy-struct in the
      create_conn() function when the connectdata struct is allocated. */
diff --git a/lib/url.h b/lib/url.h
index 3eb733a0a..7b9aff5c4 100644
--- a/lib/url.h
+++ b/lib/url.h
@@ -79,6 +79,8 @@ void Curl_getoff_all_pipelines(struct Curl_easy *data,
 
 CURLcode Curl_upkeep(struct conncache *conn_cache, void *data);
 
+const struct Curl_handler *Curl_builtin_scheme(const char *scheme);
+
 #define CURL_DEFAULT_PROXY_PORT 1080 /* default proxy port unless specified */
 #define CURL_DEFAULT_HTTPS_PROXY_PORT 443 /* default https proxy port unless
                                              specified */
diff --git a/lib/urlapi-int.h b/lib/urlapi-int.h
new file mode 100644
index 000000000..7ac09fdb5
--- /dev/null
+++ b/lib/urlapi-int.h
@@ -0,0 +1,29 @@
+#ifndef HEADER_CURL_URLAPI_INT_H
+#define HEADER_CURL_URLAPI_INT_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+#include "curl_setup.h"
+bool Curl_is_absolute_url(const char *url, char *scheme, size_t buflen);
+char *Curl_concat_url(const char *base, const char *relurl);
+size_t Curl_strlen_url(const char *url, bool relative);
+void Curl_strcpy_url(char *output, const char *url, bool relative);
+#endif
diff --git a/lib/urlapi.c b/lib/urlapi.c
new file mode 100644
index 000000000..8287861f7
--- /dev/null
+++ b/lib/urlapi.c
@@ -0,0 +1,1315 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+#include "curl_setup.h"
+
+#include "urldata.h"
+#include "urlapi-int.h"
+#include "strcase.h"
+#include "dotdot.h"
+#include "url.h"
+#include "escape.h"
+#include "curl_ctype.h"
+
+/* The last 3 #include files should be in this order */
+#include "curl_printf.h"
+#include "curl_memory.h"
+#include "memdebug.h"
+
+/* Internal representation of CURLU. Point to URL-encoded strings. */
+struct Curl_URL {
+  char *scheme;
+  char *user;
+  char *password;
+  char *options; /* IMAP only? */
+  char *host;
+  char *port;
+  char *path;
+  char *query;
+  char *fragment;
+
+  char *scratch; /* temporary scratch area */
+  long portnum; /* the numerical version */
+};
+
+#define DEFAULT_SCHEME "https"
+
+/* scheme is not URL encoded, the longest libcurl supported ones are 6
+   letters */
+#define MAX_SCHEME_LEN 8
+
+static void free_urlhandle(struct Curl_URL *u)
+{
+  free(u->scheme);
+  free(u->user);
+  free(u->password);
+  free(u->options);
+  free(u->host);
+  free(u->port);
+  free(u->path);
+  free(u->query);
+  free(u->fragment);
+  free(u->scratch);
+}
+
+/* move the full contents of one handle onto another and
+   free the original */
+static void mv_urlhandle(struct Curl_URL *from,
+                         struct Curl_URL *to)
+{
+  free_urlhandle(to);
+  *to = *from;
+  free(from);
+}
+
+/*
+ * Find the separator at the end of the host name, or the '?' in cases like
+ * http://www.url.com?id=2380
+ */
+static const char *find_host_sep(const char *url)
+{
+  const char *sep;
+  const char *query;
+
+  /* Find the start of the hostname */
+  sep = strstr(url, "//");
+  if(!sep)
+    sep = url;
+  else
+    sep += 2;
+
+  query = strchr(sep, '?');
+  sep = strchr(sep, '/');
+
+  if(!sep)
+    sep = url + strlen(url);
+
+  if(!query)
+    query = url + strlen(url);
+
+  return sep < query ? sep : query;
+}
+
+/*
+ * Decide in an encoding-independent manner whether a character in an
+ * URL must be escaped. The same criterion must be used in strlen_url()
+ * and strcpy_url().
+ */
+static bool urlchar_needs_escaping(int c)
+{
+    return !(ISCNTRL(c) || ISSPACE(c) || ISGRAPH(c));
+}
+
+/*
+ * strlen_url() returns the length of the given URL if the spaces within the
+ * URL were properly URL encoded.
+ * URL encoding should be skipped for host names, otherwise IDN resolution
+ * will fail.
+ */
+size_t Curl_strlen_url(const char *url, bool relative)
+{
+  const unsigned char *ptr;
+  size_t newlen = 0;
+  bool left = TRUE; /* left side of the ? */
+  const unsigned char *host_sep = (const unsigned char *) url;
+
+  if(!relative)
+    host_sep = (const unsigned char *) find_host_sep(url);
+
+  for(ptr = (unsigned char *)url; *ptr; ptr++) {
+
+    if(ptr < host_sep) {
+      ++newlen;
+      continue;
+    }
+
+    switch(*ptr) {
+    case '?':
+      left = FALSE;
+      /* FALLTHROUGH */
+    default:
+      if(urlchar_needs_escaping(*ptr))
+        newlen += 2;
+      newlen++;
+      break;
+    case ' ':
+      if(left)
+        newlen += 3;
+      else
+        newlen++;
+      break;
+    }
+  }
+  return newlen;
+}
+
+/* strcpy_url() copies a url to a output buffer and URL-encodes the spaces in
+ * the source URL accordingly.
+ * URL encoding should be skipped for host names, otherwise IDN resolution
+ * will fail.
+ */
+void Curl_strcpy_url(char *output, const char *url, bool relative)
+{
+  /* we must add this with whitespace-replacing */
+  bool left = TRUE;
+  const unsigned char *iptr;
+  char *optr = output;
+  const unsigned char *host_sep = (const unsigned char *) url;
+
+  if(!relative)
+    host_sep = (const unsigned char *) find_host_sep(url);
+
+  for(iptr = (unsigned char *)url;    /* read from here */
+      *iptr;         /* until zero byte */
+      iptr++) {
+
+    if(iptr < host_sep) {
+      *optr++ = *iptr;
+      continue;
+    }
+
+    switch(*iptr) {
+    case '?':
+      left = FALSE;
+      /* FALLTHROUGH */
+    default:
+      if(urlchar_needs_escaping(*iptr)) {
+        snprintf(optr, 4, "%%%02x", *iptr);
+        optr += 3;
+      }
+      else
+        *optr++=*iptr;
+      break;
+    case ' ':
+      if(left) {
+        *optr++='%'; /* add a '%' */
+        *optr++='2'; /* add a '2' */
+        *optr++='0'; /* add a '0' */
+      }
+      else
+        *optr++='+'; /* add a '+' here */
+      break;
+    }
+  }
+  *optr = 0; /* zero terminate output buffer */
+
+}
+
+/*
+ * Returns true if the given URL is absolute (as opposed to relative) within
+ * the buffer size. Returns the scheme in the buffer if TRUE and 'buf' is
+ * non-NULL.
+ */
+bool Curl_is_absolute_url(const char *url, char *buf, size_t buflen)
+{
+  size_t i;
+  for(i = 0; i < buflen && url[i]; ++i) {
+    char s = url[i];
+    if(s == ':') {
+      if(buf)
+        buf[i] = 0;
+      return TRUE;
+    }
+    /* RFC 3986 3.1 explains:
+      scheme      = ALPHA *( ALPHA / DIGIT / "+" / "-" / "." )
+    */
+    else if(ISALNUM(s) || (s == '+') || (s == '-') || (s == '.') ) {
+      if(buf)
+        buf[i] = (char)TOLOWER(s);
+    }
+    else
+      break;
+  }
+  return FALSE;
+}
+
+/*
+ * Concatenate a relative URL to a base URL making it absolute.
+ * URL-encodes any spaces.
+ * The returned pointer must be freed by the caller unless NULL
+ * (returns NULL on out of memory).
+ */
+char *Curl_concat_url(const char *base, const char *relurl)
+{
+  /***
+   TRY to append this new path to the old URL
+   to the right of the host part. Oh crap, this is doomed to cause
+   problems in the future...
+  */
+  char *newest;
+  char *protsep;
+  char *pathsep;
+  size_t newlen;
+  bool host_changed = FALSE;
+
+  const char *useurl = relurl;
+  size_t urllen;
+
+  /* we must make our own copy of the URL to play with, as it may
+     point to read-only data */
+  char *url_clone = strdup(base);
+
+  if(!url_clone)
+    return NULL; /* skip out of this NOW */
+
+  /* protsep points to the start of the host name */
+  protsep = strstr(url_clone, "//");
+  if(!protsep)
+    protsep = url_clone;
+  else
+    protsep += 2; /* pass the slashes */
+
+  if('/' != relurl[0]) {
+    int level = 0;
+
+    /* First we need to find out if there's a ?-letter in the URL,
+       and cut it and the right-side of that off */
+    pathsep = strchr(protsep, '?');
+    if(pathsep)
+      *pathsep = 0;
+
+    /* we have a relative path to append to the last slash if there's one
+       available, or if the new URL is just a query string (starts with a
+       '?')  we append the new one at the end of the entire currently worked
+       out URL */
+    if(useurl[0] != '?') {
+      pathsep = strrchr(protsep, '/');
+      if(pathsep)
+        *pathsep = 0;
+    }
+
+    /* Check if there's any slash after the host name, and if so, remember
+       that position instead */
+    pathsep = strchr(protsep, '/');
+    if(pathsep)
+      protsep = pathsep + 1;
+    else
+      protsep = NULL;
+
+    /* now deal with one "./" or any amount of "../" in the newurl
+       and act accordingly */
+
+    if((useurl[0] == '.') && (useurl[1] == '/'))
+      useurl += 2; /* just skip the "./" */
+
+    while((useurl[0] == '.') &&
+          (useurl[1] == '.') &&
+          (useurl[2] == '/')) {
+      level++;
+      useurl += 3; /* pass the "../" */
+    }
+
+    if(protsep) {
+      while(level--) {
+        /* cut off one more level from the right of the original URL */
+        pathsep = strrchr(protsep, '/');
+        if(pathsep)
+          *pathsep = 0;
+        else {
+          *protsep = 0;
+          break;
+        }
+      }
+    }
+  }
+  else {
+    /* We got a new absolute path for this server */
+
+    if((relurl[0] == '/') && (relurl[1] == '/')) {
+      /* the new URL starts with //, just keep the protocol part from the
+         original one */
+      *protsep = 0;
+      useurl = &relurl[2]; /* we keep the slashes from the original, so we
+                              skip the new ones */
+      host_changed = TRUE;
+    }
+    else {
+      /* cut off the original URL from the first slash, or deal with URLs
+         without slash */
+      pathsep = strchr(protsep, '/');
+      if(pathsep) {
+        /* When people use badly formatted URLs, such as
+           "http://www.url.com?dir=/home/daniel" we must not use the first
+           slash, if there's a ?-letter before it! */
+        char *sep = strchr(protsep, '?');
+        if(sep && (sep < pathsep))
+          pathsep = sep;
+        *pathsep = 0;
+      }
+      else {
+        /* There was no slash. Now, since we might be operating on a badly
+           formatted URL, such as "http://www.url.com?id=2380" which doesn't
+           use a slash separator as it is supposed to, we need to check for a
+           ?-letter as well! */
+        pathsep = strchr(protsep, '?');
+        if(pathsep)
+          *pathsep = 0;
+      }
+    }
+  }
+
+  /* If the new part contains a space, this is a mighty stupid redirect
+     but we still make an effort to do "right". To the left of a '?'
+     letter we replace each space with %20 while it is replaced with '+'
+     on the right side of the '?' letter.
+  */
+  newlen = Curl_strlen_url(useurl, !host_changed);
+
+  urllen = strlen(url_clone);
+
+  newest = malloc(urllen + 1 + /* possible slash */
+                  newlen + 1 /* zero byte */);
+
+  if(!newest) {
+    free(url_clone); /* don't leak this */
+    return NULL;
+  }
+
+  /* copy over the root url part */
+  memcpy(newest, url_clone, urllen);
+
+  /* check if we need to append a slash */
+  if(('/' == useurl[0]) || (protsep && !*protsep) || ('?' == useurl[0]))
+    ;
+  else
+    newest[urllen++]='/';
+
+  /* then append the new piece on the right side */
+  Curl_strcpy_url(&newest[urllen], useurl, !host_changed);
+
+  free(url_clone);
+
+  return newest;
+}
+
+/*
+ * parse_hostname_login()
+ *
+ * Parse the login details (user name, password and options) from the URL and
+ * strip them out of the host name
+ *
+ */
+static CURLUcode parse_hostname_login(struct Curl_URL *u,
+                                      const struct Curl_handler *h,
+                                      char **hostname,
+                                      unsigned int flags)
+{
+  CURLUcode result = CURLUE_OK;
+  CURLcode ccode;
+  char *userp = NULL;
+  char *passwdp = NULL;
+  char *optionsp = NULL;
+
+  /* At this point, we're hoping all the other special cases have
+   * been taken care of, so conn->host.name is at most
+   *    [user[:password][;options]]@]hostname
+   *
+   * We need somewhere to put the embedded details, so do that first.
+   */
+
+  char *ptr = strchr(*hostname, '@');
+  char *login = *hostname;
+
+  if(!ptr)
+    goto out;
+
+  /* We will now try to extract the
+   * possible login information in a string like:
+   * ftp://user:password@ftp.my.site:8021/README */
+  *hostname = ++ptr;
+
+  /* We could use the login information in the URL so extract it. Only parse
+     options if the handler says we should. */
+  ccode = Curl_parse_login_details(login, ptr - login - 1,
+                                   &userp, &passwdp,
+                                   h->flags & PROTOPT_URLOPTIONS ?
+                                   &optionsp:NULL);
+  if(ccode) {
+    result = CURLUE_MALFORMED_INPUT;
+    goto out;
+  }
+
+  if(userp) {
+    if(flags & CURLU_DISALLOW_USER) {
+      /* Option DISALLOW_USER is set and url contains username. */
+      result = CURLUE_USER_NOT_ALLOWED;
+      goto out;
+    }
+
+    u->user = userp;
+  }
+
+  if(passwdp)
+    u->password = passwdp;
+
+  if(optionsp)
+    u->options = optionsp;
+
+  return CURLUE_OK;
+  out:
+
+  free(userp);
+  free(passwdp);
+  free(optionsp);
+
+  return result;
+}
+
+static CURLUcode parse_port(struct Curl_URL *u, char *hostname)
+{
+  char *portptr;
+  char endbracket;
+  int len;
+
+  if((1 == sscanf(hostname, "[%*45[0123456789abcdefABCDEF:.]%c%n",
+                  &endbracket, &len)) &&
+     (']' == endbracket)) {
+    /* this is a RFC2732-style specified IP-address */
+    portptr = &hostname[len];
+    if (*portptr != ':')
+      return CURLUE_MALFORMED_INPUT;
+  }
+  else
+    portptr = strchr(hostname, ':');
+
+  if(portptr) {
+    char *rest;
+    long port;
+    char portbuf[7];
+
+    if(!ISDIGIT(portptr[1]))
+      return CURLUE_BAD_PORT_NUMBER;
+
+    port = strtol(portptr + 1, &rest, 10);  /* Port number must be decimal */
+
+    if((port <= 0) || (port > 0xffff))
+      /* Single unix standard says port numbers are 16 bits long, but we don't
+         treat port zero as OK. */
+      return CURLUE_BAD_PORT_NUMBER;
+
+    if(rest[0])
+      return CURLUE_BAD_PORT_NUMBER;
+
+    if(rest != &portptr[1]) {
+      *portptr++ = '\0'; /* cut off the name there */
+      *rest = 0;
+      /* generate a new to get rid of leading zeroes etc */
+      snprintf(portbuf, sizeof(portbuf), "%ld", port);
+      u->portnum = port;
+      u->port = strdup(portbuf);
+      if(!u->port)
+        return CURLUE_OUT_OF_MEMORY;
+    }
+    else {
+      /* Browser behavior adaptation. If there's a colon with no digits after,
+         just cut off the name there which makes us ignore the colon and just
+         use the default port. Firefox and Chrome both do that. */
+      *portptr = '\0';
+    }
+  }
+
+  return CURLUE_OK;
+}
+
+/* scan for byte values < 31 or 127 */
+static CURLUcode junkscan(char *part)
+{
+  char badbytes[]={
+    /* */ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+    0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+    0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+    0x7f,
+    0x00 /* zero terminate */
+  };
+  if(part) {
+    size_t n = strlen(part);
+    size_t nfine = strcspn(part, badbytes);
+    if(nfine != n)
+      /* since we don't know which part is scanned, return a generic error
+         code */
+      return CURLUE_MALFORMED_INPUT;
+  }
+  return CURLUE_OK;
+}
+
+static CURLUcode hostname_check(char *hostname, unsigned int flags)
+{
+  const char *l; /* accepted characters */
+  size_t len;
+  size_t hlen = strlen(hostname);
+  (void)flags;
+
+  if(hostname[0] == '[') {
+    hostname++;
+    l = "0123456789abcdefABCDEF::.";
+    hlen -= 2;
+  }
+  else /* % for URL escaped letters */
+    l = "0123456789abcdefghijklimnopqrstuvwxyz-_.ABCDEFGHIJKLIMNOPQRSTUVWXYZ%";
+
+  len = strspn(hostname, l);
+  if(hlen != len)
+    /* hostname with bad content */
+    return CURLUE_MALFORMED_INPUT;
+
+  return CURLUE_OK;
+}
+
+#define HOSTNAME_END(x) (((x) == '/') || ((x) == '?') || ((x) == '#'))
+
+static CURLUcode seturl(const char *url, CURLU *u, unsigned int flags)
+{
+  char *path;
+  bool path_alloced = FALSE;
+  char *hostname;
+  char *query = NULL;
+  char *fragment = NULL;
+  CURLUcode result;
+  bool url_has_scheme = FALSE;
+  char schemebuf[MAX_SCHEME_LEN];
+  char *schemep;
+  size_t schemelen = 0;
+  size_t urllen;
+  const struct Curl_handler *h = NULL;
+
+  if(!url)
+    return CURLUE_MALFORMED_INPUT;
+
+  /*************************************************************
+   * Parse the URL.
+   ************************************************************/
+  /* allocate scratch area */
+  urllen = strlen(url);
+  path = u->scratch = malloc(urllen * 2 + 2);
+  if(!path)
+    return CURLUE_OUT_OF_MEMORY;
+
+  hostname = &path[urllen + 1];
+  hostname[0] = 0;
+
+  /* MSDOS/Windows style drive prefix, eg c: in c:foo */
+#define STARTS_WITH_DRIVE_PREFIX(str) \
+  ((('a' <= str[0] && str[0] <= 'z') || \
+    ('A' <= str[0] && str[0] <= 'Z')) && \
+   (str[1] == ':'))
+
+  /* MSDOS/Windows style drive prefix, optionally with
+   * a '|' instead of ':', followed by a slash or NUL */
+#define STARTS_WITH_URL_DRIVE_PREFIX(str) \
+  ((('a' <= (str)[0] && (str)[0] <= 'z') || \
+    ('A' <= (str)[0] && (str)[0] <= 'Z')) && \
+   ((str)[1] == ':' || (str)[1] == '|') && \
+   ((str)[2] == '/' || (str)[2] == '\\' || (str)[2] == 0))
+
+  if(Curl_is_absolute_url(url, schemebuf, sizeof(schemebuf))) {
+    url_has_scheme = TRUE;
+    schemelen = strlen(schemebuf);
+  }
+
+  /* handle the file: scheme */
+  if(url_has_scheme && strcasecompare(schemebuf, "file")) {
+    /* path has been allocated large anough to hold this */
+    strcpy(path, &url[5]);
+
+    hostname = NULL; /* no host for file: URLs */
+    u->scheme = strdup("file");
+    if(!u->scheme)
+      return CURLUE_OUT_OF_MEMORY;
+
+    /* Extra handling URLs with an authority component (i.e. that start with
+     * "file://")
+     *
+     * We allow omitted hostname (e.g. file:/<path>) -- valid according to
+     * RFC 8089, but not the (current) WHAT-WG URL spec.
+     */
+    if(path[0] == '/' && path[1] == '/') {
+      /* swallow the two slashes */
+      char *ptr = &path[2];
+
+      /*
+       * According to RFC 8089, a file: URL can be reliably dereferenced if:
+       *
+       *  o it has no/blank hostname, or
+       *
+       *  o the hostname matches "localhost" (case-insensitively), or
+       *
+       *  o the hostname is a FQDN that resolves to this machine.
+       *
+       * For brevity, we only consider URLs with empty, "localhost", or
+       * "127.0.0.1" hostnames as local.
+       *
+       * Additionally, there is an exception for URLs with a Windows drive
+       * letter in the authority (which was accidentally omitted from RFC 8089
+       * Appendix E, but believe me, it was meant to be there. --MK)
+       */
+      if(ptr[0] != '/' && !STARTS_WITH_URL_DRIVE_PREFIX(ptr)) {
+        /* the URL includes a host name, it must match "localhost" or
+           "127.0.0.1" to be valid */
+        if(!checkprefix("localhost/", ptr) &&
+           !checkprefix("127.0.0.1/", ptr)) {
+          /* Invalid file://hostname/, expected localhost or 127.0.0.1 or
+             none */
+          return CURLUE_MALFORMED_INPUT;
+        }
+        ptr += 9; /* now points to the slash after the host */
+      }
+
+      path = ptr;
+    }
+
+#if !defined(MSDOS) && !defined(WIN32) && !defined(__CYGWIN__)
+    /* Don't allow Windows drive letters when not in Windows.
+     * This catches both "file:/c:" and "file:c:" */
+    if(('/' == path[0] && STARTS_WITH_URL_DRIVE_PREFIX(&path[1])) ||
+       STARTS_WITH_URL_DRIVE_PREFIX(path)) {
+      /* File drive letters are only accepted in MSDOS/Windows */
+      return CURLUE_MALFORMED_INPUT;
+    }
+#else
+    /* If the path starts with a slash and a drive letter, ditch the slash */
+    if('/' == path[0] && STARTS_WITH_URL_DRIVE_PREFIX(&path[1])) {
+      /* This cannot be done with strcpy, as the memory chunks overlap! */
+      memmove(path, &path[1], strlen(&path[1]) + 1);
+    }
+#endif
+
+  }
+  else {
+    /* clear path */
+    const char *p;
+    const char *hostp;
+    size_t len;
+    path[0] = 0;
+
+    if(url_has_scheme) {
+      int i = 0;
+      p = &url[schemelen + 1];
+      while(p && (*p == '/') && (i < 4)) {
+        p++;
+        i++;
+      }
+      if((i < 1) || (i>3))
+        /* less than one or more than three slashes */
+        return CURLUE_MALFORMED_INPUT;
+
+      schemep = schemebuf;
+      if(!Curl_builtin_scheme(schemep) &&
+         !(flags & CURLU_NON_SUPPORT_SCHEME))
+        return CURLUE_UNSUPPORTED_SCHEME;
+
+      if(junkscan(schemep))
+        return CURLUE_MALFORMED_INPUT;
+    }
+    else {
+      /* no scheme! */
+
+      if(!(flags & CURLU_DEFAULT_SCHEME))
+        return CURLUE_MALFORMED_INPUT;
+      schemep = (char *) DEFAULT_SCHEME;
+
+      /*
+       * The URL was badly formatted, let's try without scheme specified.
+       */
+      p = url;
+    }
+    hostp = p; /* host name starts here */
+
+    while(*p && !HOSTNAME_END(*p)) /* find end of host name */
+      p++;
+
+    len = p - hostp;
+    if(!len)
+      return CURLUE_MALFORMED_INPUT;
+
+    memcpy(hostname, hostp, len);
+    hostname[len] = 0;
+
+    len = strlen(p);
+    memcpy(path, p, len);
+    path[len] = 0;
+
+    u->scheme = strdup(schemep);
+    if(!u->scheme)
+      return CURLUE_OUT_OF_MEMORY;
+  }
+
+  /* if this is a known scheme, get some details */
+  h = Curl_builtin_scheme(u->scheme);
+
+  if(junkscan(path))
+    return CURLUE_MALFORMED_INPUT;
+
+  query = strchr(path, '?');
+  if(query)
+    *query++ = 0;
+
+  fragment = strchr(query?query:path, '#');
+  if(fragment)
+    *fragment++ = 0;
+
+  if(!path[0])
+    /* if there's no path set, unset */
+    path = NULL;
+  else if(!(flags & CURLU_PATH_AS_IS)) {
+    /* sanitise paths and remove ../ and ./ sequences according to RFC3986 */
+    char *newp = Curl_dedotdotify(path);
+    if(!newp)
+      return CURLUE_OUT_OF_MEMORY;
+
+    if(strcmp(newp, path)) {
+      /* if we got a new version */
+      path = newp;
+      path_alloced = TRUE;
+    }
+    else
+      free(newp);
+  }
+  if(path) {
+    u->path = path_alloced?path:strdup(path);
+    if(!u->path)
+      return CURLUE_OUT_OF_MEMORY;
+  }
+
+  if(hostname) {
+    /*
+     * Parse the login details and strip them out of the host name.
+     */
+    if(junkscan(hostname))
+      return CURLUE_MALFORMED_INPUT;
+
+    result = parse_hostname_login(u, h, &hostname, flags);
+    if(result)
+      return result;
+
+    result = parse_port(u, hostname);
+    if(result)
+      return result;
+
+    result = hostname_check(hostname, flags);
+    if(result)
+      return result;
+
+    u->host = strdup(hostname);
+    if(!u->host)
+      return CURLUE_OUT_OF_MEMORY;
+  }
+
+  if(query && query[0]) {
+    u->query = strdup(query);
+    if(!u->query)
+      return CURLUE_OUT_OF_MEMORY;
+  }
+  if(fragment && fragment[0]) {
+    u->fragment = strdup(fragment);
+    if(!u->fragment)
+      return CURLUE_OUT_OF_MEMORY;
+  }
+
+  free(u->scratch);
+  u->scratch = NULL;
+
+  return CURLUE_OK;
+}
+
+/*
+ * Parse the URL and set the relevant members of the Curl_URL struct.
+ */
+static CURLUcode parseurl(const char *url, CURLU *u, unsigned int flags)
+{
+  CURLUcode result = seturl(url, u, flags);
+  if(result) {
+    free_urlhandle(u);
+    memset(u, 0, sizeof(struct Curl_URL));
+  }
+  return result;
+}
+
+/*
+ */
+CURLU *curl_url(void)
+{
+  return calloc(sizeof(struct Curl_URL), 1);
+}
+
+void curl_url_cleanup(CURLU *u)
+{
+  if(u) {
+    free_urlhandle(u);
+    free(u);
+  }
+}
+
+#define DUP(dest, src, name)         \
+  if(src->name) {                    \
+    dest->name = strdup(src->name);  \
+    if(!dest->name)                  \
+      goto fail;                     \
+  }
+
+CURLU *curl_url_dup(CURLU *in)
+{
+  struct Curl_URL *u = calloc(sizeof(struct Curl_URL), 1);
+  if(u) {
+    DUP(u, in, scheme);
+    DUP(u, in, user);
+    DUP(u, in, password);
+    DUP(u, in, options);
+    DUP(u, in, host);
+    DUP(u, in, port);
+    DUP(u, in, path);
+    DUP(u, in, query);
+    DUP(u, in, fragment);
+    u->portnum = in->portnum;
+  }
+  return u;
+  fail:
+  curl_url_cleanup(u);
+  return NULL;
+}
+
+CURLUcode curl_url_get(CURLU *u, CURLUPart what,
+                       char **part, unsigned int flags)
+{
+  char *ptr;
+  CURLUcode ifmissing = CURLUE_UNKNOWN_PART;
+  char portbuf[7];
+  bool urldecode = (flags & CURLU_URLDECODE)?1:0;
+  bool plusdecode = FALSE;
+  (void)flags;
+  if(!u)
+    return CURLUE_BAD_HANDLE;
+  if(!part)
+    return CURLUE_BAD_PARTPOINTER;
+  *part = NULL;
+
+  switch(what) {
+  case CURLUPART_SCHEME:
+    ptr = u->scheme;
+    ifmissing = CURLUE_NO_SCHEME;
+    urldecode = FALSE; /* never for schemes */
+    break;
+  case CURLUPART_USER:
+    ptr = u->user;
+    ifmissing = CURLUE_NO_USER;
+    break;
+  case CURLUPART_PASSWORD:
+    ptr = u->password;
+    ifmissing = CURLUE_NO_PASSWORD;
+    break;
+  case CURLUPART_OPTIONS:
+    ptr = u->options;
+    ifmissing = CURLUE_NO_OPTIONS;
+    break;
+  case CURLUPART_HOST:
+    ptr = u->host;
+    ifmissing = CURLUE_NO_HOST;
+    break;
+  case CURLUPART_PORT:
+    ptr = u->port;
+    ifmissing = CURLUE_NO_PORT;
+    urldecode = FALSE; /* never for port */
+    if(!ptr && (flags & CURLU_DEFAULT_PORT) && u->scheme) {
+      /* there's no stored port number, but asked to deliver
+         a default one for the scheme */
+      const struct Curl_handler *h =
+        Curl_builtin_scheme(u->scheme);
+      if(h) {
+        snprintf(portbuf, sizeof(portbuf), "%ld", h->defport);
+        ptr = portbuf;
+      }
+    }
+    else if(ptr && u->scheme) {
+      /* there is a stored port number, but ask to inhibit if
+         it matches the default one for the scheme */
+      const struct Curl_handler *h =
+        Curl_builtin_scheme(u->scheme);
+      if(h && (h->defport == u->portnum) &&
+         (flags & CURLU_NO_DEFAULT_PORT))
+        ptr = NULL;
+    }
+    break;
+  case CURLUPART_PATH:
+    ptr = u->path;
+    if(!ptr) {
+      ptr = u->path = strdup("/");
+      if(!u->path)
+        return CURLUE_OUT_OF_MEMORY;
+    }
+    break;
+  case CURLUPART_QUERY:
+    ptr = u->query;
+    ifmissing = CURLUE_NO_QUERY;
+    plusdecode = urldecode;
+    break;
+  case CURLUPART_FRAGMENT:
+    ptr = u->fragment;
+    ifmissing = CURLUE_NO_FRAGMENT;
+    break;
+  case CURLUPART_URL: {
+    char *url;
+    char *scheme;
+    char *options = u->options;
+    char *port = u->port;
+    urldecode = FALSE; /* not for the whole thing */
+    if(u->scheme && strcasecompare("file", u->scheme)) {
+      url = aprintf("file://%s%s%s",
+                    u->path,
+                    u->fragment? "#": "",
+                    u->fragment? u->fragment : "");
+    }
+    else if(!u->host)
+      return CURLUE_NO_HOST;
+    else {
+      const struct Curl_handler *h = NULL;
+      if(u->scheme)
+        scheme = u->scheme;
+      else if(flags & CURLU_DEFAULT_SCHEME)
+        scheme = (char *) DEFAULT_SCHEME;
+      else
+        return CURLUE_NO_SCHEME;
+
+      if(scheme) {
+        h = Curl_builtin_scheme(scheme);
+        if(!port && (flags & CURLU_DEFAULT_PORT)) {
+          /* there's no stored port number, but asked to deliver
+             a default one for the scheme */
+          if(h) {
+            snprintf(portbuf, sizeof(portbuf), "%ld", h->defport);
+            port = portbuf;
+          }
+        }
+        else if(port) {
+          /* there is a stored port number, but asked to inhibit if it matches
+             the default one for the scheme */
+          if(h && (h->defport == u->portnum) &&
+             (flags & CURLU_NO_DEFAULT_PORT))
+            port = NULL;
+        }
+      }
+      if(h && !(h->flags & PROTOPT_URLOPTIONS))
+        options = NULL;
+
+      url = aprintf("%s://%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
+                    scheme,
+                    u->user ? u->user : "",
+                    u->password ? ":": "",
+                    u->password ? u->password : "",
+                    options ? ";" : "",
+                    options ? options : "",
+                    (u->user || u->password || options) ? "@": "",
+                    u->host,
+                    port ? ":": "",
+                    port ? port : "",
+                    (u->path && (u->path[0] != '/')) ? "/": "",
+                    u->path ? u->path : "/",
+                    u->query? "?": "",
+                    u->query? u->query : "",
+                    u->fragment? "#": "",
+                    u->fragment? u->fragment : "");
+    }
+    if(!url)
+      return CURLUE_OUT_OF_MEMORY;
+    *part = url;
+    return CURLUE_OK;
+    break;
+  }
+  default:
+    ptr = NULL;
+  }
+  if(ptr) {
+    *part = strdup(ptr);
+    if(!*part)
+      return CURLUE_OUT_OF_MEMORY;
+    if(plusdecode) {
+      /* convert + to space */
+      char *plus;
+      for(plus = *part; *plus; ++plus) {
+        if(*plus == '+')
+          *plus = ' ';
+      }
+    }
+    if(urldecode) {
+      char *decoded;
+      size_t dlen;
+      CURLcode res = Curl_urldecode(NULL, *part, 0, &decoded, &dlen, TRUE);
+      free(*part);
+      if(res) {
+        *part = NULL;
+        return CURLUE_URLDECODE;
+      }
+      *part = decoded;
+    }
+    return CURLUE_OK;
+  }
+  else
+    return ifmissing;
+}
+
+CURLUcode curl_url_set(CURLU *u, CURLUPart what,
+                       const char *part, unsigned int flags)
+{
+  char **storep = NULL;
+  long port = 0;
+  bool urlencode = (flags & CURLU_URLENCODE)? 1 : 0;
+  bool plusencode = FALSE;
+  bool urlskipslash = FALSE;
+  bool appendquery = FALSE;
+
+  if(!u)
+    return CURLUE_BAD_HANDLE;
+  if(!part) {
+    /* setting a part to NULL clears it */
+    switch(what) {
+    case CURLUPART_URL:
+      break;
+    case CURLUPART_SCHEME:
+      storep = &u->scheme;
+      break;
+    case CURLUPART_USER:
+      storep = &u->user;
+      break;
+    case CURLUPART_PASSWORD:
+      storep = &u->password;
+      break;
+    case CURLUPART_OPTIONS:
+      storep = &u->options;
+      break;
+    case CURLUPART_HOST:
+      storep = &u->host;
+      break;
+    case CURLUPART_PORT:
+      storep = &u->port;
+      break;
+    case CURLUPART_PATH:
+      storep = &u->path;
+      break;
+    case CURLUPART_QUERY:
+      storep = &u->query;
+      break;
+    case CURLUPART_FRAGMENT:
+      storep = &u->fragment;
+      break;
+    default:
+      return CURLUE_UNKNOWN_PART;
+    }
+    if(storep && *storep) {
+      free(*storep);
+      *storep = NULL;
+    }
+    return CURLUE_OK;
+  }
+
+  switch(what) {
+  case CURLUPART_SCHEME:
+    if(!(flags & CURLU_NON_SUPPORT_SCHEME) &&
+       /* verify that it is a fine scheme */
+       !Curl_builtin_scheme(part))
+      return CURLUE_UNSUPPORTED_SCHEME;
+    storep = &u->scheme;
+    urlencode = FALSE; /* never */
+    break;
+  case CURLUPART_USER:
+    storep = &u->user;
+    break;
+  case CURLUPART_PASSWORD:
+    storep = &u->password;
+    break;
+  case CURLUPART_OPTIONS:
+    storep = &u->options;
+    break;
+  case CURLUPART_HOST:
+    storep = &u->host;
+    break;
+  case CURLUPART_PORT:
+    urlencode = FALSE; /* never */
+    port = strtol(part, NULL, 10);  /* Port number must be decimal */
+    if((port <= 0) || (port > 0xffff))
+      return CURLUE_BAD_PORT_NUMBER;
+    storep = &u->port;
+    break;
+  case CURLUPART_PATH:
+    urlskipslash = TRUE;
+    storep = &u->path;
+    break;
+  case CURLUPART_QUERY:
+    plusencode = urlencode;
+    appendquery = (flags & CURLU_APPENDQUERY)?1:0;
+    storep = &u->query;
+    break;
+  case CURLUPART_FRAGMENT:
+    storep = &u->fragment;
+    break;
+  case CURLUPART_URL: {
+    /*
+     * Allow a new URL to replace the existing (if any) contents.
+     *
+     * If the existing contents is enough for a URL, allow a relative URL to
+     * replace it.
+     */
+    CURLUcode result;
+    char *oldurl;
+    char *redired_url;
+    CURLU *handle2;
+
+    if(Curl_is_absolute_url(part, NULL, MAX_SCHEME_LEN)) {
+      handle2 = curl_url();
+      if(!handle2)
+        return CURLUE_OUT_OF_MEMORY;
+      result = parseurl(part, handle2, flags);
+      if(!result)
+        mv_urlhandle(handle2, u);
+      else
+        curl_url_cleanup(handle2);
+      return result;
+    }
+    /* extract the full "old" URL to do the redirect on */
+    result = curl_url_get(u, CURLUPART_URL, &oldurl, flags);
+    if(result) {
+      /* couldn't get the old URL, just use the new! */
+      handle2 = curl_url();
+      if(!handle2)
+        return CURLUE_OUT_OF_MEMORY;
+      result = parseurl(part, handle2, flags);
+      if(!result)
+        mv_urlhandle(handle2, u);
+      else
+        curl_url_cleanup(handle2);
+      return result;
+    }
+
+    /* apply the relative part to create a new URL */
+    redired_url = Curl_concat_url(oldurl, part);
+    free(oldurl);
+    if(!redired_url)
+      return CURLUE_OUT_OF_MEMORY;
+
+    /* now parse the new URL */
+    handle2 = curl_url();
+    if(!handle2) {
+      free(redired_url);
+      return CURLUE_OUT_OF_MEMORY;
+    }
+    result = parseurl(redired_url, handle2, flags);
+    free(redired_url);
+    if(!result)
+      mv_urlhandle(handle2, u);
+    else
+      curl_url_cleanup(handle2);
+    return result;
+  }
+  default:
+    return CURLUE_UNKNOWN_PART;
+  }
+  if(storep) {
+    const char *newp = part;
+    size_t nalloc = strlen(part);
+
+    if(urlencode) {
+      const char *i;
+      char *o;
+      bool free_part = FALSE;
+      char *enc = malloc(nalloc * 3 + 1); /* for worst case! */
+      if(!enc)
+        return CURLUE_OUT_OF_MEMORY;
+      if(plusencode) {
+        /* space to plus */
+        i = part;
+        for(o = enc; *i; ++o, ++i)
+          *o = (*i == ' ') ? '+' : *i;
+        *o = 0; /* zero terminate */
+        part = strdup(enc);
+        if(!part) {
+          free(enc);
+          return CURLUE_OUT_OF_MEMORY;
+        }
+        free_part = TRUE;
+      }
+      for(i = part, o = enc; *i; i++) {
+        if(Curl_isunreserved(*i) ||
+           ((*i == '/') && urlskipslash) ||
+           ((*i == '=') && appendquery) ||
+           ((*i == '+') && plusencode)) {
+          *o = *i;
+          o++;
+        }
+        else {
+          snprintf(o, 4, "%%%02x", *i);
+          o += 3;
+        }
+      }
+      *o = 0; /* zero terminate */
+      newp = enc;
+      if(free_part)
+        free((char *)part);
+    }
+    else {
+      char *p;
+      newp = strdup(part);
+      if(!newp)
+        return CURLUE_OUT_OF_MEMORY;
+      p = (char *)newp;
+      while(*p) {
+        /* make sure percent encoded are lower case */
+        if((*p == '%') && ISXDIGIT(p[1]) && ISXDIGIT(p[2]) &&
+           (ISUPPER(p[1]) || ISUPPER(p[2]))) {
+          p[1] = (char)TOLOWER(p[1]);
+          p[2] = (char)TOLOWER(p[2]);
+          p += 3;
+        }
+        else
+          p++;
+      }
+    }
+
+    if(appendquery) {
+      /* Append the string onto the old query. Add a '&' separator if none is
+         present at the end of the exsting query already */
+      size_t querylen = u->query ? strlen(u->query) : 0;
+      bool addamperand = querylen && (u->query[querylen -1] != '&');
+      if(querylen) {
+        size_t newplen = strlen(newp);
+        char *p = malloc(querylen + addamperand + newplen + 1);
+        if(!p) {
+          free((char *)newp);
+          return CURLUE_OUT_OF_MEMORY;
+        }
+        strcpy(p, u->query); /* original query */
+        if(addamperand)
+          p[querylen] = '&'; /* ampersand */
+        strcpy(&p[querylen + addamperand], newp); /* new suffix */
+        free((char *)newp);
+        free(*storep);
+        *storep = p;
+        return CURLUE_OK;
+      }
+    }
+
+    free(*storep);
+    *storep = (char *)newp;
+  }
+  /* set after the string, to make it not assigned if the allocation above
+     fails */
+  if(port)
+    u->portnum = port;
+  return CURLUE_OK;
+}