CURLOPT_MIME_OPTIONS(3) Library Functions Manual CURLOPT_MIME_OPTIONS(3)

CURLOPT_MIME_OPTIONS - set MIME option flags

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_MIME_OPTIONS, long options);

Pass a long that holds a bitmask of CURLMIMEOPT_* defines. Each bit is a Boolean flag used while encoding a MIME tree or multipart form data.

Available bits are:

Tells libcurl to escape multipart form field and filenames using the backslash-escaping algorithm rather than percent-encoding (HTTP only).

Backslash-escaping consists in preceding backslashes and double quotes with a backslash. Percent encoding maps all occurrences of double quote, carriage return and line feed to %22, %0D and %0A respectively.

Before version 7.81.0, percent-encoding was never applied.

HTTP browsers used to do backslash-escaping in the past but have over time transitioned to use percent-encoding. This option allows one to address server-side applications that have not yet have been converted.

As an example, consider field or filename strangename"kind. When the containing multipart form is sent, this is normally transmitted as strangename%22kind. When this option is set, it is sent as strangename"kind.

0, meaning disabled.

HTTP, IMAP and SMTP

int main(void)
{
  CURL *curl = curl_easy_init();
  curl_mime *form = NULL;
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    curl_easy_setopt(curl, CURLOPT_MIME_OPTIONS, CURLMIMEOPT_FORMESCAPE);
    form = curl_mime_init(curl);
    if(form) {
      curl_mimepart *part = curl_mime_addpart(form);
      if(part) {
        curl_mime_filedata(part, "strange\\file\\name");
        curl_mime_name(part, "strange\"field\"name");
        curl_easy_setopt(curl, CURLOPT_MIMEPOST, form);
        /* Perform the request */
        curl_easy_perform(curl);
      }
    }
    curl_easy_cleanup(curl);
    curl_mime_free(form);
  }
}

Option added in 7.81.0.

Returns CURLE_OK

CURLOPT_HTTPPOST(3), CURLOPT_MIMEPOST(3)

2024-05-22 libcurl