.\" generated by cd2nroff 0.1 from CURLOPT_SSH_HOSTKEYDATA.md
.TH CURLOPT_SSH_HOSTKEYDATA 3 "2025-02-13" libcurl
.SH NAME
CURLOPT_SSH_HOSTKEYDATA \- pointer to pass to the SSH host key callback
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_HOSTKEYDATA, void *pointer);
.fi
.SH DESCRIPTION
Pass a void * as parameter. This \fIpointer\fP is passed along untouched to
the callback set with \fICURLOPT_SSH_HOSTKEYFUNCTION(3)\fP.
.SH DEFAULT
NULL
.SH PROTOCOLS
This functionality affects scp and sftp
.SH EXAMPLE
.nf
struct mine {
  void *custom;
};

static int hostkeycb(void *clientp,   /* CURLOPT_SSH_HOSTKEYDATA */
                     int keytype,     /* CURLKHTYPE */
                     const char *key, /* host key to check */
                     size_t keylen)   /* length of the key */
{
  /* 'clientp' points to the callback_data struct */
  /* investigate the situation and return the correct value */
  return CURLKHMATCH_OK;
}

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    struct mine callback_data;
    curl_easy_setopt(curl, CURLOPT_URL, "sftp://example.com/thisfile.txt");
    curl_easy_setopt(curl, CURLOPT_SSH_HOSTKEYFUNCTION, hostkeycb);
    curl_easy_setopt(curl, CURLOPT_SSH_HOSTKEYDATA, &callback_data);

    curl_easy_perform(curl);
  }
}
.fi
.SH NOTES
Works only with the libssh2 backend.
.SH AVAILABILITY
Added in curl 7.84.0
.SH RETURN VALUE
\fIcurl_easy_setopt(3)\fP returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non\-zero means an error occurred, see
\fIlibcurl\-errors(3)\fP.
.SH SEE ALSO
.BR CURLOPT_SSH_HOSTKEYFUNCTION (3)