url.c

   *   (a comma-separated list of hosts which should
   *   not be proxied, or an asterisk to override
   *   all proxy variables)
   */
  size_t tok_start;
  size_t tok_end;
  const char* separator = ", ";
  size_t no_proxy_len;
  size_t namelen;
  char *endptr;

  if(no_proxy && no_proxy[0]) {
    if(Curl_raw_equal("*", no_proxy)) {
      return TRUE;
    }

    /* NO_PROXY was specified and it wasn't just an asterisk */

    no_proxy_len = strlen(no_proxy);
    endptr = strchr(name, ':');
    if(endptr)
      namelen = endptr - name;
    else
      namelen = strlen(name);

    for(tok_start = 0; tok_start < no_proxy_len; tok_start = tok_end + 1) {
      while(tok_start < no_proxy_len &&
            strchr(separator, no_proxy[tok_start]) != NULL) {
        /* Look for the beginning of the token. */
        ++tok_start;
      }

      if(tok_start == no_proxy_len)
        break; /* It was all trailing separator chars, no more tokens. */

      for(tok_end = tok_start; tok_end < no_proxy_len &&
            strchr(separator, no_proxy[tok_end]) == NULL; ++tok_end)
        /* Look for the end of the token. */
        ;

      /* To match previous behaviour, where it was necessary to specify
       * ".local.com" to prevent matching "notlocal.com", we will leave
       * the '.' off.
       */
      if(no_proxy[tok_start] == '.')
        ++tok_start;

      if((tok_end - tok_start) <= namelen) {
        /* Match the last part of the name to the domain we are checking. */
        const char *checkn = name + namelen - (tok_end - tok_start);
        if(Curl_raw_nequal(no_proxy + tok_start, checkn,
                           tok_end - tok_start)) {
          if((tok_end - tok_start) == namelen || *(checkn - 1) == '.') {
            /* We either have an exact match, or the previous character is a .
             * so it is within the same domain, so no proxy for this host.
             */
            return TRUE;
          }
        }
      } /* if((tok_end - tok_start) <= namelen) */
    } /* for(tok_start = 0; tok_start < no_proxy_len;
         tok_start = tok_end + 1) */
  } /* NO_PROXY was specified and it wasn't just an asterisk */

  return FALSE;
}

/****************************************************************
* Detect what (if any) proxy to use. Remember that this selects a host
* name and is not limited to HTTP proxies only.
* The returned pointer must be freed by the caller (unless NULL)
****************************************************************/
static char *detect_proxy(struct connectdata *conn)
{
  char *proxy = NULL;

#ifndef CURL_DISABLE_HTTP
  /* If proxy was not specified, we check for default proxy environment
   * variables, to enable i.e Lynx compliance:
   *
   * http_proxy=http://some.server.dom:port/
   * https_proxy=http://some.server.dom:port/
   * ftp_proxy=http://some.server.dom:port/
   * no_proxy=domain1.dom,host.domain2.dom
   *   (a comma-separated list of hosts which should
   *   not be proxied, or an asterisk to override
   *   all proxy variables)
   * all_proxy=http://some.server.dom:port/
   *   (seems to exist for the CERN www lib. Probably
   *   the first to check for.)
   *
   * For compatibility, the all-uppercase versions of these variables are
   * checked if the lowercase versions don't exist.
   */
  char *no_proxy=NULL;
  char proxy_env[128];

  no_proxy=curl_getenv("no_proxy");
  if(!no_proxy)
    no_proxy=curl_getenv("NO_PROXY");

  if(!check_noproxy(conn->host.name, no_proxy)) {
    /* It was not listed as without proxy */
    const char *protop = conn->handler->scheme;
    char *envp = proxy_env;
    char *prox;

    /* Now, build <protocol>_proxy and check for such a one to use */
    while(*protop)
      *envp++ = (char)tolower((int)*protop++);

    /* append _proxy */
    strcpy(envp, "_proxy");

    /* read the protocol proxy: */
    prox=curl_getenv(proxy_env);

    /*
     * We don't try the uppercase version of HTTP_PROXY because of
     * security reasons:
     *
     * When curl is used in a webserver application
     * environment (cgi or php), this environment variable can
     * be controlled by the web server user by setting the
     * http header 'Proxy:' to some value.
     *
     * This can cause 'internal' http/ftp requests to be
     * arbitrarily redirected by any external attacker.
     */
    if(!prox && !Curl_raw_equal("http_proxy", proxy_env)) {
      /* There was no lowercase variable, try the uppercase version: */
      Curl_strntoupper(proxy_env, proxy_env, sizeof(proxy_env));
      prox=curl_getenv(proxy_env);
    }

    if(prox && *prox) { /* don't count "" strings */
      proxy = prox; /* use this */
    }
    else {
      proxy = curl_getenv("all_proxy"); /* default proxy to use */
      if(!proxy)
        proxy=curl_getenv("ALL_PROXY");
    }
  } /* if(!check_noproxy(conn->host.name, no_proxy)) - it wasn't specified
       non-proxy */
  if(no_proxy)
    free(no_proxy);

#else /* !CURL_DISABLE_HTTP */

  (void)conn;
#endif /* CURL_DISABLE_HTTP */

  return proxy;
}

/*
 * If this is supposed to use a proxy, we need to figure out the proxy
 * host name, so that we can re-use an existing connection
 * that may exist registered to the same proxy host.
 * proxy will be freed before this function returns.
 */
static CURLcode parse_proxy(struct SessionHandle *data,
                            struct connectdata *conn, char *proxy)
{
  char *prox_portno;
  char *endofprot;

  /* We use 'proxyptr' to point to the proxy name from now on... */
  char *proxyptr;
  char *portptr;
  char *atsign;

  /* We do the proxy host string parsing here. We want the host name and the
   * port name. Accept a protocol:// prefix
   */

  /* Parse the protocol part if present */
  endofprot = strstr(proxy, "://");
  if(endofprot) {
    proxyptr = endofprot+3;
    if(checkprefix("socks5h", proxy))
      conn->proxytype = CURLPROXY_SOCKS5_HOSTNAME;
    else if(checkprefix("socks5", proxy))
      conn->proxytype = CURLPROXY_SOCKS5;
    else if(checkprefix("socks4a", proxy))
      conn->proxytype = CURLPROXY_SOCKS4A;
    else if(checkprefix("socks4", proxy) || checkprefix("socks", proxy))
      conn->proxytype = CURLPROXY_SOCKS4;
    /* Any other xxx:// : change to http proxy */
  }
  else
    proxyptr = proxy; /* No xxx:// head: It's a HTTP proxy */

  /* Is there a username and password given in this proxy url? */
  atsign = strchr(proxyptr, '@');
  if(atsign) {
    char proxyuser[MAX_CURL_USER_LENGTH];
    char proxypasswd[MAX_CURL_PASSWORD_LENGTH];
    proxypasswd[0] = 0;

    if(1 <= sscanf(proxyptr,
                   "%" MAX_CURL_USER_LENGTH_TXT"[^:@]:"
                   "%" MAX_CURL_PASSWORD_LENGTH_TXT "[^@]",
                   proxyuser, proxypasswd)) {
      CURLcode res = CURLE_OK;

      /* found user and password, rip them out.  note that we are
         unescaping them, as there is otherwise no way to have a
         username or password with reserved characters like ':' in
         them. */
      Curl_safefree(conn->proxyuser);
      conn->proxyuser = curl_easy_unescape(data, proxyuser, 0, NULL);

      if(!conn->proxyuser)
        res = CURLE_OUT_OF_MEMORY;
      else {
        Curl_safefree(conn->proxypasswd);
        conn->proxypasswd = curl_easy_unescape(data, proxypasswd, 0, NULL);

        if(!conn->proxypasswd)
          res = CURLE_OUT_OF_MEMORY;
      }

      if(CURLE_OK == res) {
        conn->bits.proxy_user_passwd = TRUE; /* enable it */
        atsign++; /* the right side of the @-letter */

        if(atsign)
          proxyptr = atsign; /* now use this instead */
        else
          res = CURLE_OUT_OF_MEMORY;
      }

      if(res)
        return res;
    }
  }

  /* start scanning for port number at this point */
  portptr = proxyptr;

  /* detect and extract RFC2732-style IPv6-addresses */
  if(*proxyptr == '[') {
    char *ptr = ++proxyptr; /* advance beyond the initial bracket */
    while(*ptr && (ISXDIGIT(*ptr) || (*ptr == ':') || (*ptr == '%') ||
                   (*ptr == '.')))
      ptr++;
    if(*ptr == ']')
      /* yeps, it ended nicely with a bracket as well */
      *ptr++ = 0;
    else
      infof(data, "Invalid IPv6 address format\n");
    portptr = ptr;
    /* Note that if this didn't end with a bracket, we still advanced the
     * proxyptr first, but I can't see anything wrong with that as no host
     * name nor a numeric can legally start with a bracket.
     */
  }

  /* Get port number off proxy.server.com:1080 */
  prox_portno = strchr(portptr, ':');
  if(prox_portno) {
    *prox_portno = 0x0; /* cut off number from host name */
    prox_portno ++;
    /* now set the local port number */
    conn->port = strtol(prox_portno, NULL, 10);
  }
  else {
    if(proxyptr[0]=='/')
      /* If the first character in the proxy string is a slash, fail
         immediately. The following code will otherwise clear the string which
         will lead to code running as if no proxy was set! */
      return CURLE_COULDNT_RESOLVE_PROXY;

    /* without a port number after the host name, some people seem to use
       a slash so we strip everything from the first slash */
    atsign = strchr(proxyptr, '/');
    if(atsign)
      *atsign = 0x0; /* cut off path part from host name */

    if(data->set.proxyport)
      /* None given in the proxy string, then get the default one if it is
         given */
      conn->port = data->set.proxyport;
  }

  /* now, clone the cleaned proxy host name */
  conn->proxy.rawalloc = strdup(proxyptr);
  conn->proxy.name = conn->proxy.rawalloc;

  if(!conn->proxy.rawalloc)
    return CURLE_OUT_OF_MEMORY;

  return CURLE_OK;
}

/*
 * Extract the user and password from the authentication string
 */
static CURLcode parse_proxy_auth(struct SessionHandle *data,
                                 struct connectdata *conn)
{
  char proxyuser[MAX_CURL_USER_LENGTH]="";
  char proxypasswd[MAX_CURL_PASSWORD_LENGTH]="";

  if(data->set.str[STRING_PROXYUSERNAME] != NULL) {
    strncpy(proxyuser, data->set.str[STRING_PROXYUSERNAME],
            MAX_CURL_USER_LENGTH);
    proxyuser[MAX_CURL_USER_LENGTH-1] = '\0';   /*To be on safe side*/
  }
  if(data->set.str[STRING_PROXYPASSWORD] != NULL) {
    strncpy(proxypasswd, data->set.str[STRING_PROXYPASSWORD],
            MAX_CURL_PASSWORD_LENGTH);
    proxypasswd[MAX_CURL_PASSWORD_LENGTH-1] = '\0'; /*To be on safe side*/
  }

  conn->proxyuser = curl_easy_unescape(data, proxyuser, 0, NULL);
  if(!conn->proxyuser)
    return CURLE_OUT_OF_MEMORY;

  conn->proxypasswd = curl_easy_unescape(data, proxypasswd, 0, NULL);
  if(!conn->proxypasswd)
    return CURLE_OUT_OF_MEMORY;

  return CURLE_OK;
}
#endif /* CURL_DISABLE_PROXY */

/*
 *
 * Parse a user name and password in the URL and strip it out of the host name
 *
 * Inputs: data->set.use_netrc (CURLOPT_NETRC)
 *         conn->host.name
 *
 * Outputs: (almost :- all currently undefined)
 *          conn->bits.user_passwd  - non-zero if non-default passwords exist
 *          user                    - non-zero length if defined
 *          passwd                  -   ditto
 *          conn->host.name         - remove user name and password
 */
static CURLcode parse_url_userpass(struct SessionHandle *data,
                                   struct connectdata *conn,
                                   char *user, char *passwd)
{
  /* 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]]@]hostname
   *
   * We need somewhere to put the embedded details, so do that first.
   */

  char *ptr=strchr(conn->host.name, '@');
  char *userpass = conn->host.name;

  user[0] =0;   /* to make everything well-defined */
  passwd[0]=0;

  /* We will now try to extract the
   * possible user+password pair in a string like:
   * ftp://user:password@ftp.my.site:8021/README */
  if(ptr != NULL) {
    /* there's a user+password given here, to the left of the @ */

    conn->host.name = ++ptr;

    /* So the hostname is sane.  Only bother interpreting the
     * results if we could care.  It could still be wasted
     * work because it might be overtaken by the programmatically
     * set user/passwd, but doing that first adds more cases here :-(
     */

    conn->bits.userpwd_in_url = TRUE;
    if(data->set.use_netrc != CURL_NETRC_REQUIRED) {
      /* We could use the one in the URL */

      conn->bits.user_passwd = TRUE; /* enable user+password */

      if(*userpass != ':') {
        /* the name is given, get user+password */
        sscanf(userpass, "%" MAX_CURL_USER_LENGTH_TXT "[^:@]:"
               "%" MAX_CURL_PASSWORD_LENGTH_TXT "[^@]",
               user, passwd);
      }
      else
        /* no name given, get the password only */
        sscanf(userpass, ":%" MAX_CURL_PASSWORD_LENGTH_TXT "[^@]", passwd);

      if(user[0]) {
        char *newname=curl_easy_unescape(data, user, 0, NULL);
        if(!newname)
          return CURLE_OUT_OF_MEMORY;
        if(strlen(newname) < MAX_CURL_USER_LENGTH)
          strcpy(user, newname);

        /* if the new name is longer than accepted, then just use
           the unconverted name, it'll be wrong but what the heck */
        free(newname);
      }
      if(passwd[0]) {
        /* we have a password found in the URL, decode it! */
        char *newpasswd=curl_easy_unescape(data, passwd, 0, NULL);
        if(!newpasswd)
          return CURLE_OUT_OF_MEMORY;
        if(strlen(newpasswd) < MAX_CURL_PASSWORD_LENGTH)
          strcpy(passwd, newpasswd);

        free(newpasswd);
      }
    }
  }
  return CURLE_OK;
}

/*************************************************************
 * Figure out the remote port number and fix it in the URL
 *
 * No matter if we use a proxy or not, we have to figure out the remote
 * port number of various reasons.
 *
 * To be able to detect port number flawlessly, we must not confuse them
 * IPv6-specified addresses in the [0::1] style. (RFC2732)
 *
 * The conn->host.name is currently [user:passwd@]host[:port] where host
 * could be a hostname, IPv4 address or IPv6 address.
 *
 * The port number embedded in the URL is replaced, if necessary.
 *************************************************************/
static CURLcode parse_remote_port(struct SessionHandle *data,
                                  struct connectdata *conn)
{
  char *portptr;
  char endbracket;

  /* Note that at this point, the IPv6 address cannot contain any scope
     suffix as that has already been removed in the parseurlandfillconn()
     function */
  if((1 == sscanf(conn->host.name, "[%*45[0123456789abcdefABCDEF:.]%c",
                  &endbracket)) &&
     (']' == endbracket)) {
    /* this is a RFC2732-style specified IP-address */
    conn->bits.ipv6_ip = TRUE;

    conn->host.name++; /* skip over the starting bracket */
    portptr = strchr(conn->host.name, ']');
    if(portptr) {
      *portptr++ = '\0'; /* zero terminate, killing the bracket */
      if(':' != *portptr)
        portptr = NULL; /* no port number available */
    }
  }
  else {
#ifdef ENABLE_IPV6
    struct in6_addr in6;
    if(Curl_inet_pton(AF_INET6, conn->host.name, &in6) > 0) {
      /* This is a numerical IPv6 address, meaning this is a wrongly formatted
         URL */
      failf(data, "IPv6 numerical address used in URL without brackets");
      return CURLE_URL_MALFORMAT;
    }
#endif

    portptr = strrchr(conn->host.name, ':');
  }

  if(data->set.use_port && data->state.allow_port) {
    /* if set, we use this and ignore the port possibly given in the URL */
    conn->remote_port = (unsigned short)data->set.use_port;
    if(portptr)
      *portptr = '\0'; /* cut off the name there anyway - if there was a port
                      number - since the port number is to be ignored! */
    if(conn->bits.httpproxy) {
      /* we need to create new URL with the new port number */
      char *url;
      char type[12]="";

      if(conn->bits.type_set)
        snprintf(type, sizeof(type), ";type=%c",
                 data->set.prefer_ascii?'A':
                 (data->set.ftp_list_only?'D':'I'));

      /*
       * This synthesized URL isn't always right--suffixes like ;type=A are
       * stripped off. It would be better to work directly from the original
       * URL and simply replace the port part of it.
       */
      url = aprintf("%s://%s%s%s:%hu%s%s%s", conn->given->scheme,
                    conn->bits.ipv6_ip?"[":"", conn->host.name,
                    conn->bits.ipv6_ip?"]":"", conn->remote_port,
                    data->state.slash_removed?"/":"", data->state.path,
                    type);
      if(!url)
        return CURLE_OUT_OF_MEMORY;

      if(data->change.url_alloc) {
        Curl_safefree(data->change.url);
        data->change.url_alloc = FALSE;
      }

      data->change.url = url;
      data->change.url_alloc = TRUE;
    }
  }
  else if(portptr) {
    /* no CURLOPT_PORT given, extract the one from the URL */

    char *rest;
    unsigned long port;

    port=strtoul(portptr+1, &rest, 10);  /* Port number must be decimal */

    if(rest != (portptr+1) && *rest == '\0') {
      /* The colon really did have only digits after it,
       * so it is either a port number or a mistake */

      if(port > 0xffff) {   /* Single unix standard says port numbers are
                              * 16 bits long */
        failf(data, "Port number too large: %lu", port);
        return CURLE_URL_MALFORMAT;
      }

      *portptr = '\0'; /* cut off the name there */
      conn->remote_port = curlx_ultous(port);
    }
    else if(!port)
      /* 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 CURLE_OK;
}

/*
 * Override a user name and password from the URL with that in the
 * CURLOPT_USERPWD option or a .netrc file, if applicable.
 */
static void override_userpass(struct SessionHandle *data,
                              struct connectdata *conn,
                              char *user, char *passwd)
{
  if(data->set.str[STRING_USERNAME] != NULL) {
    strncpy(user, data->set.str[STRING_USERNAME], MAX_CURL_USER_LENGTH);
    user[MAX_CURL_USER_LENGTH-1] = '\0';   /*To be on safe side*/
  }
  if(data->set.str[STRING_PASSWORD] != NULL) {
    strncpy(passwd, data->set.str[STRING_PASSWORD], MAX_CURL_PASSWORD_LENGTH);
    passwd[MAX_CURL_PASSWORD_LENGTH-1] = '\0'; /*To be on safe side*/
  }

  conn->bits.netrc = FALSE;
  if(data->set.use_netrc != CURL_NETRC_IGNORED) {
    if(Curl_parsenetrc(conn->host.name,
                       user, passwd,
                       data->set.str[STRING_NETRC_FILE])) {
      infof(data, "Couldn't find host %s in the "
            DOT_CHAR "netrc file; using defaults\n",
            conn->host.name);
    }
    else {
      /* set bits.netrc TRUE to remember that we got the name from a .netrc
         file, so that it is safe to use even if we followed a Location: to a
         different host or similar. */
      conn->bits.netrc = TRUE;

      conn->bits.user_passwd = TRUE; /* enable user+password */
    }
  }
}

/*
 * Set password so it's available in the connection.
 */
static CURLcode set_userpass(struct connectdata *conn,
                             const char *user, const char *passwd)
{
  /* If our protocol needs a password and we have none, use the defaults */
  if((conn->handler->flags & PROTOPT_NEEDSPWD) &&
     !conn->bits.user_passwd) {

    conn->user = strdup(CURL_DEFAULT_USER);
    if(conn->user)
      conn->passwd = strdup(CURL_DEFAULT_PASSWORD);
    else
      conn->passwd = NULL;
    /* This is the default password, so DON'T set conn->bits.user_passwd */
  }
  else {
    /* store user + password, zero-length if not set */
    conn->user = strdup(user);
    if(conn->user)
      conn->passwd = strdup(passwd);
    else
      conn->passwd = NULL;
  }
  if(!conn->user || !conn->passwd)
    return CURLE_OUT_OF_MEMORY;

  return CURLE_OK;
}

/*************************************************************
 * Resolve the address of the server or proxy
 *************************************************************/
static CURLcode resolve_server(struct SessionHandle *data,
                               struct connectdata *conn,
                               bool *async)
{
  CURLcode result=CURLE_OK;
  long timeout_ms = Curl_timeleft(data, NULL, TRUE);

  /*************************************************************
   * Resolve the name of the server or proxy
   *************************************************************/
  if(conn->bits.reuse)
    /* We're reusing the connection - no need to resolve anything, and
       fix_hostname() was called already in create_conn() for the re-use
       case. */
    *async = FALSE;

  else {
    /* this is a fresh connect */
    int rc;
    struct Curl_dns_entry *hostaddr;

    /* set a pointer to the hostname we display */
    fix_hostname(data, conn, &conn->host);

    if(!conn->proxy.name || !*conn->proxy.name) {
      /* If not connecting via a proxy, extract the port from the URL, if it is
       * there, thus overriding any defaults that might have been set above. */
      conn->port =  conn->remote_port; /* it is the same port */

      /* Resolve target host right on */
      rc = Curl_resolv_timeout(conn, conn->host.name, (int)conn->port,
                               &hostaddr, timeout_ms);
      if(rc == CURLRESOLV_PENDING)
        *async = TRUE;

      else if(rc == CURLRESOLV_TIMEDOUT)
        result = CURLE_OPERATION_TIMEDOUT;

      else if(!hostaddr) {
        failf(data, "Couldn't resolve host '%s'", conn->host.dispname);
        result =  CURLE_COULDNT_RESOLVE_HOST;
        /* don't return yet, we need to clean up the timeout first */
      }
    }
    else {
      /* This is a proxy that hasn't been resolved yet. */

      /* IDN-fix the proxy name */
      fix_hostname(data, conn, &conn->proxy);

      /* resolve proxy */
      rc = Curl_resolv_timeout(conn, conn->proxy.name, (int)conn->port,
                               &hostaddr, timeout_ms);

      if(rc == CURLRESOLV_PENDING)
        *async = TRUE;

      else if(rc == CURLRESOLV_TIMEDOUT)
        result = CURLE_OPERATION_TIMEDOUT;

      else if(!hostaddr) {
        failf(data, "Couldn't resolve proxy '%s'", conn->proxy.dispname);
        result = CURLE_COULDNT_RESOLVE_PROXY;
        /* don't return yet, we need to clean up the timeout first */
      }
    }
    DEBUGASSERT(conn->dns_entry == NULL);
    conn->dns_entry = hostaddr;
  }

  return result;
}

/*
 * Cleanup the connection just allocated before we can move along and use the
 * previously existing one.  All relevant data is copied over and old_conn is
 * ready for freeing once this function returns.
 */
static void reuse_conn(struct connectdata *old_conn,
                       struct connectdata *conn)
{
  if(old_conn->proxy.rawalloc)
    free(old_conn->proxy.rawalloc);

  /* free the SSL config struct from this connection struct as this was
     allocated in vain and is targeted for destruction */
  Curl_free_ssl_config(&old_conn->ssl_config);

  conn->data = old_conn->data;

  /* get the user+password information from the old_conn struct since it may
   * be new for this request even when we re-use an existing connection */
  conn->bits.user_passwd = old_conn->bits.user_passwd;
  if(conn->bits.user_passwd) {
    /* use the new user name and password though */
    Curl_safefree(conn->user);
    Curl_safefree(conn->passwd);
    conn->user = old_conn->user;
    conn->passwd = old_conn->passwd;
    old_conn->user = NULL;
    old_conn->passwd = NULL;
  }

  conn->bits.proxy_user_passwd = old_conn->bits.proxy_user_passwd;
  if(conn->bits.proxy_user_passwd) {
    /* use the new proxy user name and proxy password though */
    Curl_safefree(conn->proxyuser);
    Curl_safefree(conn->proxypasswd);
    conn->proxyuser = old_conn->proxyuser;
    conn->proxypasswd = old_conn->proxypasswd;
    old_conn->proxyuser = NULL;
    old_conn->proxypasswd = NULL;
  }

  /* host can change, when doing keepalive with a proxy or if the case is
     different this time etc */
  Curl_safefree(conn->host.rawalloc);
  conn->host=old_conn->host;

  /* persist connection info in session handle */
  Curl_persistconninfo(conn);

  /* re-use init */
  conn->bits.reuse = TRUE; /* yes, we're re-using here */

  Curl_safefree(old_conn->user);
  Curl_safefree(old_conn->passwd);
  Curl_safefree(old_conn->proxyuser);
  Curl_safefree(old_conn->proxypasswd);
  Curl_safefree(old_conn->localdev);

  Curl_llist_destroy(old_conn->send_pipe, NULL);
  Curl_llist_destroy(old_conn->recv_pipe, NULL);

  old_conn->send_pipe = NULL;
  old_conn->recv_pipe = NULL;

  Curl_safefree(old_conn->master_buffer);
}

/**
 * create_conn() sets up a new connectdata struct, or re-uses an already
 * existing one, and resolves host name.
 *
 * if this function returns CURLE_OK and *async is set to TRUE, the resolve
 * response will be coming asynchronously. If *async is FALSE, the name is
 * already resolved.
 *
 * @param data The sessionhandle pointer
 * @param in_connect is set to the next connection data pointer
 * @param async is set TRUE when an async DNS resolution is pending
 * @see Curl_setup_conn()
 *
 * *NOTE* this function assigns the conn->data pointer!
 */

static CURLcode create_conn(struct SessionHandle *data,
                            struct connectdata **in_connect,
                            bool *async)
{
  CURLcode result=CURLE_OK;
  struct connectdata *conn;
  struct connectdata *conn_temp = NULL;
  size_t urllen;
  char user[MAX_CURL_USER_LENGTH];
  char passwd[MAX_CURL_PASSWORD_LENGTH];
  bool reuse;
  char *proxy = NULL;
  bool prot_missing = FALSE;
  bool no_connections_available = FALSE;
  bool force_reuse;
  size_t max_host_connections = Curl_multi_max_host_connections(data->multi);
  size_t max_total_connections = Curl_multi_max_total_connections(data->multi);

  *async = FALSE;

  /*************************************************************
   * Check input data
   *************************************************************/

  if(!data->change.url)
    return CURLE_URL_MALFORMAT;

  /* First, split up the current URL in parts so that we can use the
     parts for checking against the already present connections. In order
     to not have to modify everything at once, we allocate a temporary
     connection data struct and fill in for comparison purposes. */
  conn = allocate_conn(data);

  if(!conn)
    return CURLE_OUT_OF_MEMORY;

  /* We must set the return variable as soon as possible, so that our
     parent can cleanup any possible allocs we may have done before
     any failure */
  *in_connect = conn;

  /* This initing continues below, see the comment "Continue connectdata
   * initialization here" */

  /***********************************************************
   * We need to allocate memory to store the path in. We get the size of the
   * full URL to be sure, and we need to make it at least 256 bytes since
   * other parts of the code will rely on this fact
   ***********************************************************/
#define LEAST_PATH_ALLOC 256
  urllen=strlen(data->change.url);
  if(urllen < LEAST_PATH_ALLOC)
    urllen=LEAST_PATH_ALLOC;

  /*
   * We malloc() the buffers below urllen+2 to make room for 2 possibilities:
   * 1 - an extra terminating zero
   * 2 - an extra slash (in case a syntax like "www.host.com?moo" is used)
   */

  Curl_safefree(data->state.pathbuffer);
  data->state.path = NULL;

  data->state.pathbuffer = malloc(urllen+2);
  if(NULL == data->state.pathbuffer)
    return CURLE_OUT_OF_MEMORY; /* really bad error */
  data->state.path = data->state.pathbuffer;

  conn->host.rawalloc = malloc(urllen+2);
  if(NULL == conn->host.rawalloc) {
    Curl_safefree(data->state.pathbuffer);
    data->state.path = NULL;
    return CURLE_OUT_OF_MEMORY;
  }

  conn->host.name = conn->host.rawalloc;
  conn->host.name[0] = 0;

  result = parseurlandfillconn(data, conn, &prot_missing, user, passwd);
  if(result != CURLE_OK)
    return result;

  /*************************************************************
   * No protocol part in URL was used, add it!
   *************************************************************/
  if(prot_missing) {
    /* We're guessing prefixes here and if we're told to use a proxy or if
       we're gonna follow a Location: later or... then we need the protocol
       part added so that we have a valid URL. */
    char *reurl;

    reurl = aprintf("%s://%s", conn->handler->scheme, data->change.url);

    if(!reurl) {
      Curl_safefree(proxy);
      return CURLE_OUT_OF_MEMORY;
    }

    if(data->change.url_alloc) {
      Curl_safefree(data->change.url);
      data->change.url_alloc = FALSE;
    }

    data->change.url = reurl;
    data->change.url_alloc = TRUE; /* free this later */
  }

  /*************************************************************
   * If the protocol can't handle url query strings, then cut
   * of the unhandable part
   *************************************************************/
  if((conn->given->flags&PROTOPT_NOURLQUERY)) {
    char *path_q_sep = strchr(conn->data->state.path, '?');
    if(path_q_sep) {
      /* according to rfc3986, allow the query (?foo=bar)
         also on protocols that can't handle it.

         cut the string-part after '?'
      */

      /* terminate the string */
      path_q_sep[0] = 0;
    }
  }

#ifndef CURL_DISABLE_PROXY
  /*************************************************************
   * Extract the user and password from the authentication string
   *************************************************************/
  if(conn->bits.proxy_user_passwd) {
    result = parse_proxy_auth(data, conn);
    if(result != CURLE_OK)
      return result;
  }

  /*************************************************************
   * Detect what (if any) proxy to use
   *************************************************************/
  if(data->set.str[STRING_PROXY]) {
    proxy = strdup(data->set.str[STRING_PROXY]);
    /* if global proxy is set, this is it */
    if(NULL == proxy) {
      failf(data, "memory shortage");
      return CURLE_OUT_OF_MEMORY;
    }
  }

  if(data->set.str[STRING_NOPROXY] &&
     check_noproxy(conn->host.name, data->set.str[STRING_NOPROXY])) {
    if(proxy) {
      free(proxy);  /* proxy is in exception list */
      proxy = NULL;
    }
  }
  else if(!proxy)
    proxy = detect_proxy(conn);

  if(proxy && (!*proxy || (conn->handler->flags & PROTOPT_NONETWORK))) {
    free(proxy);  /* Don't bother with an empty proxy string or if the
                     protocol doesn't work with network */
    proxy = NULL;
  }

  /***********************************************************************
   * If this is supposed to use a proxy, we need to figure out the proxy host
   * name, proxy type and port number, so that we can re-use an existing
   * connection that may exist registered to the same proxy host.
   ***********************************************************************/
  if(proxy) {
    result = parse_proxy(data, conn, proxy);

    free(proxy); /* parse_proxy copies the proxy string */

    if(result)
      return result;

    if((conn->proxytype == CURLPROXY_HTTP) ||
       (conn->proxytype == CURLPROXY_HTTP_1_0)) {
#ifdef CURL_DISABLE_HTTP
      /* asking for a HTTP proxy is a bit funny when HTTP is disabled... */
      return CURLE_UNSUPPORTED_PROTOCOL;
#else
      /* force this connection's protocol to become HTTP if not already
         compatible - if it isn't tunneling through */
      if(!(conn->handler->protocol & CURLPROTO_HTTP) &&
         !conn->bits.tunnel_proxy)
        conn->handler = &Curl_handler_http;

      conn->bits.httpproxy = TRUE;
#endif
    }
    else
      conn->bits.httpproxy = FALSE; /* not a HTTP proxy */
    conn->bits.proxy = TRUE;
  }
  else {
    /* we aren't using the proxy after all... */
    conn->bits.proxy = FALSE;
    conn->bits.httpproxy = FALSE;
    conn->bits.proxy_user_passwd = FALSE;
    conn->bits.tunnel_proxy = FALSE;
  }

#endif /* CURL_DISABLE_PROXY */

  /*************************************************************
   * Setup internals depending on protocol. Needs to be done after
   * we figured out what/if proxy to use.
   *************************************************************/
  result = setup_connection_internals(conn);
  if(result != CURLE_OK) {
    Curl_safefree(proxy);
    return result;
  }

  conn->recv[FIRSTSOCKET] = Curl_recv_plain;
  conn->send[FIRSTSOCKET] = Curl_send_plain;
  conn->recv[SECONDARYSOCKET] = Curl_recv_plain;
  conn->send[SECONDARYSOCKET] = Curl_send_plain;

  /***********************************************************************
   * file: is a special case in that it doesn't need a network connection
   ***********************************************************************/
#ifndef CURL_DISABLE_FILE
  if(conn->handler->flags & PROTOPT_NONETWORK) {
    bool done;
    /* this is supposed to be the connect function so we better at least check
       that the file is present here! */
    DEBUGASSERT(conn->handler->connect_it);
    result = conn->handler->connect_it(conn, &done);

    /* Setup a "faked" transfer that'll do nothing */
    if(CURLE_OK == result) {
      conn->data = data;
      conn->bits.tcpconnect[FIRSTSOCKET] = TRUE; /* we are "connected */

      ConnectionStore(data, conn);

      /*