---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_DEFAULT_PROTOCOL
Section: 3
Source: libcurl
See-also:
  - CURLINFO_PROTOCOL (3)
  - CURLINFO_SCHEME (3)
  - CURLOPT_URL (3)
---

# NAME

CURLOPT_DEFAULT_PROTOCOL - default protocol to use if the URL is missing a
scheme name

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DEFAULT_PROTOCOL,
                          char *protocol);
~~~

# DESCRIPTION

This option tells libcurl to use *protocol* if the URL is missing a scheme
name.

Use one of these protocol (scheme) names:

dict, file, ftp, ftps, gopher, http, https, imap, imaps, ldap, ldaps, pop3,
pop3s, rtsp, scp, sftp, smb, smbs, smtp, smtps, telnet, tftp

An unknown or unsupported protocol causes error
*CURLE_UNSUPPORTED_PROTOCOL* when libcurl parses a URL without a
scheme. Parsing happens when curl_easy_perform(3) or
curl_multi_perform(3) is called. The protocol set supported by libcurl
vary depending on how it was built. Use curl_version_info(3) if you need
a list of protocol names supported by the build of libcurl that you are using.

This option does not change the default proxy protocol (http).

Without this option libcurl would make a guess based on the host, see
CURLOPT_URL(3) for details.

The application does not have to keep the string around after setting this
option.

# DEFAULT

NULL (make a guess based on the host)

# PROTOCOLS

All

# EXAMPLE

~~~c
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    /* set a URL without a scheme */
    curl_easy_setopt(curl, CURLOPT_URL, "example.com");

    /* set the default protocol (scheme) for schemeless URLs */
    curl_easy_setopt(curl, CURLOPT_DEFAULT_PROTOCOL, "https");

    /* Perform the request */
    curl_easy_perform(curl);
  }
}
~~~

# AVAILABILITY

Added in 7.45.0

# RETURN VALUE

CURLE_OK if the option is supported.

CURLE_OUT_OF_MEMORY if there was insufficient heap space.

CURLE_UNKNOWN_OPTION if the option is not supported.