libssh2_knownhost_check(3) libssh2 manual libssh2_knownhost_check(3)NAME
libssh2_knownhost_checkp - check a host+key against the list of known hosts
SYNOPSIS
#include <libssh2.h>
int libssh2_knownhost_checkp(LIBSSH2_KNOWNHOSTS *hosts,
const char *host, int port,
const char *key, size_t keylen,
int typemask,
struct libssh2_knownhost **knownhost);
DESCRIPTION
Checks a host and its associated key against the collection of known hosts, and returns info back about the (partially) matched entry.
host is a pointer the host name in plain text. The host name can be the IP numerical address of the host or the full name.
port is the port number used by the host (or a negative number to check the generic host). If the port number is given, libssh2 will check
the key for the specific host + port number combination in addition to the plain host name only check.
key is a pointer to the key for the given host.
keylen is the total size in bytes of the key pointed to by the key argument
typemask is a bitmask that specifies format and info about the data passed to this function. Specificly, it details what format the host
name is, what format the key is and what key type it is.
The host name is given as one of the following types: LIBSSH2_KNOWNHOST_TYPE_PLAIN or LIBSSH2_KNOWNHOST_TYPE_CUSTOM.
The key is encoded using one of the following encodings: LIBSSH2_KNOWNHOST_KEYENC_RAW or LIBSSH2_KNOWNHOST_KEYENC_BASE64.
knownhost if set to non-NULL, it must be a pointer to a 'struct libssh2_knownhost' pointer that gets filled in to point to info about a
known host that matches or partially matches.
RETURN VALUE libssh2_knownhost_check(3) returns info about how well the provided host + key pair matched one of the entries in the list of known hosts.
LIBSSH2_KNOWNHOST_CHECK_FAILURE - something prevented the check to be made
LIBSSH2_KNOWNHOST_CHECK_NOTFOUND - no host match was found
LIBSSH2_KNOWNHOST_CHECK_MATCH - hosts and keys match.
LIBSSH2_KNOWNHOST_CHECK_MISMATCH - host was found, but the keys didn't match!
AVAILABILITY
Added in libssh2 1.2.6
EXAMPLE
See the ssh2_exec.c example as provided in the tarball.
SEE ALSO libssh2_knownhost_init(3)libssh2_knownhost_free(3)libssh2_knownhost_add(3)libssh2 1.2.6 1 May 2010 libssh2_knownhost_check(3)
Check Out this Related Man Page
CURLOPT_SSH_KEYFUNCTION(3) curl_easy_setopt options CURLOPT_SSH_KEYFUNCTION(3)NAME
CURLOPT_SSH_KEYFUNCTION - callback for known host matching logic
SYNOPSIS
#include <curl/curl.h>
enum curl_khstat {
CURLKHSTAT_FINE_ADD_TO_FILE,
CURLKHSTAT_FINE,
CURLKHSTAT_REJECT, /* reject the connection, return an error */
CURLKHSTAT_DEFER, /* do not accept it, but we can't answer right
now so this causes a CURLE_DEFER error but
otherwise the connection will be left intact
etc */
};
enum curl_khmatch {
CURLKHMATCH_OK, /* match */
CURLKHMATCH_MISMATCH, /* host found, key mismatch! */
CURLKHMATCH_MISSING, /* no matching host/key found */
};
struct curl_khkey {
const char *key; /* points to a zero-terminated string encoded with
base64 if len is zero, otherwise to the "raw"
data */
size_t len;
enum curl_khtype keytype;
};
int ssh_keycallback(CURL *easy,
const struct curl_khkey *knownkey,
const struct curl_khkey *foundkey,
enum curl_khmatch,
void *clientp);
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_KEYFUNCTION,
ssh_keycallback);
DESCRIPTION
Pass a pointer to your callback function, which should match the prototype shown above.
It gets called when the known_host matching has been done, to allow the application to act and decide for libcurl how to proceed. The call-
back will only be called if CURLOPT_SSH_KNOWNHOSTS(3) is also set.
This callback function gets passed the CURL handle, the key from the known_hosts file knownkey, the key from the remote site foundkey, info
from libcurl on the matching status and a custom pointer (set with CURLOPT_SSH_KEYDATA(3)). It MUST return one of the following return
codes to tell libcurl how to act:
CURLKHSTAT_FINE_ADD_TO_FILE
The host+key is accepted and libcurl will append it to the known_hosts file before continuing with the connection. This will also
add the host+key combo to the known_host pool kept in memory if it wasn't already present there. The adding of data to the file is
done by completely replacing the file with a new copy, so the permissions of the file must allow this.
CURLKHSTAT_FINE
The host+key is accepted libcurl will continue with the connection. This will also add the host+key combo to the known_host pool
kept in memory if it wasn't already present there.
CURLKHSTAT_REJECT
The host+key is rejected. libcurl will deny the connection to continue and it will be closed.
CURLKHSTAT_DEFER
The host+key is rejected, but the SSH connection is asked to be kept alive. This feature could be used when the app wants to some-
how return back and act on the host+key situation and then retry without needing the overhead of setting it up from scratch again.
DEFAULT
NULL
PROTOCOLS
SFTP and SCP
EXAMPLE
TODO
AVAILABILITY
Added in 7.19.6
RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
SEE ALSO CURLOPT_SSH_KEYDATA(3), CURLOPT_SSH_KNOWNHOSTS(3),
libcurl 7.54.0 February 03, 2016 CURLOPT_SSH_KEYFUNCTION(3)