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5b060a4108
... instead of using future tense. + numerous cleanups and improvements + stick to "reuse" not "re-use" + fewer contractions Closes #11713
133 lines
5.3 KiB
Groff
133 lines
5.3 KiB
Groff
.\" **************************************************************************
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.\" * _ _ ____ _
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.\" * Project ___| | | | _ \| |
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.\" * / __| | | | |_) | |
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.\" * | (__| |_| | _ <| |___
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.\" * \___|\___/|_| \_\_____|
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.\" *
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.\" * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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.\" *
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.\" * This software is licensed as described in the file COPYING, which
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.\" * you should have received as part of this distribution. The terms
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.\" * are also available at https://curl.se/docs/copyright.html.
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.\" *
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.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
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.\" * copies of the Software, and permit persons to whom the Software is
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.\" * furnished to do so, under the terms of the COPYING file.
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.\" *
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.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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.\" * KIND, either express or implied.
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.\" *
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.\" * SPDX-License-Identifier: curl
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.\" *
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.\" **************************************************************************
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.\"
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.TH CURLOPT_SSH_KEYFUNCTION 3 "19 Jun 2014" libcurl libcurl
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.SH NAME
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CURLOPT_SSH_KEYFUNCTION \- callback for known host matching logic
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.SH SYNOPSIS
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.nf
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#include <curl/curl.h>
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enum curl_khstat {
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CURLKHSTAT_FINE_ADD_TO_FILE,
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CURLKHSTAT_FINE,
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CURLKHSTAT_REJECT, /* reject the connection, return an error */
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CURLKHSTAT_DEFER, /* do not accept it, but we cannot answer right
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now. Causes a CURLE_PEER_FAILED_VERIFICATION error but
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the connection is left intact */
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CURLKHSTAT_FINE_REPLACE
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};
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enum curl_khmatch {
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CURLKHMATCH_OK, /* match */
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CURLKHMATCH_MISMATCH, /* host found, key mismatch! */
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CURLKHMATCH_MISSING, /* no matching host/key found */
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};
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struct curl_khkey {
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const char *key; /* points to a null-terminated string encoded with
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base64 if len is zero, otherwise to the "raw"
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data */
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size_t len;
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enum curl_khtype keytype;
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};
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int ssh_keycallback(CURL *easy,
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const struct curl_khkey *knownkey,
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const struct curl_khkey *foundkey,
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enum curl_khmatch match,
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void *clientp);
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_KEYFUNCTION,
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ssh_keycallback);
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.SH DESCRIPTION
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Pass a pointer to your callback function, which should match the prototype
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shown above.
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It gets called when the known_host matching has been done, to allow the
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application to act and decide for libcurl how to proceed. The callback is only
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called if \fICURLOPT_SSH_KNOWNHOSTS(3)\fP is also set.
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This callback function gets passed the CURL handle, the key from the
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known_hosts file \fIknownkey\fP, the key from the remote site \fIfoundkey\fP,
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info from libcurl on the matching status and a custom pointer (set with
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\fICURLOPT_SSH_KEYDATA(3)\fP). It MUST return one of the following return
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codes to tell libcurl how to act:
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.IP CURLKHSTAT_FINE_REPLACE
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The new host+key is accepted and libcurl replaces the old host+key into the
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known_hosts file before continuing with the connection. This also adds the new
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host+key combo to the known_host pool kept in memory if it was not already
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present there. The adding of data to the file is done by completely replacing
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the file with a new copy, so the permissions of the file must allow
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this. (Added in 7.73.0)
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.IP CURLKHSTAT_FINE_ADD_TO_FILE
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The host+key is accepted and libcurl appends it to the known_hosts file before
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continuing with the connection. This also adds the host+key combo to the
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known_host pool kept in memory if it was not already present there. The adding
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of data to the file is done by completely replacing the file with a new copy,
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so the permissions of the file must allow this.
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.IP CURLKHSTAT_FINE
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The host+key is accepted libcurl continues with the connection. This also adds
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the host+key combo to the known_host pool kept in memory if it was not already
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present there.
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.IP CURLKHSTAT_REJECT
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The host+key is rejected. libcurl denies the connection to continue and it is
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closed.
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.IP CURLKHSTAT_DEFER
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The host+key is rejected, but the SSH connection is asked to be kept alive.
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This feature could be used when the app wants to somehow return back and act
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on the host+key situation and then retry without needing the overhead of
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setting it up from scratch again.
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.SH DEFAULT
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NULL
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.SH PROTOCOLS
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SFTP and SCP
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.SH EXAMPLE
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.nf
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static int keycb(CURL *easy,
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const struct curl_khkey *knownkey,
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const struct curl_khkey *foundkey,
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enum curl_khmatch match,
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void *clientp)
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{
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/* 'clientp' points to the callback_data struct */
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/* investigate the situation and return the correct value */
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return CURLKHSTAT_FINE_ADD_TO_FILE;
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}
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{
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curl_easy_setopt(curl, CURLOPT_URL, "sftp://example.com/thisfile.txt");
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curl_easy_setopt(curl, CURLOPT_SSH_KEYFUNCTION, keycb);
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curl_easy_setopt(curl, CURLOPT_SSH_KEYDATA, &callback_data);
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curl_easy_setopt(curl, CURLOPT_SSH_KNOWNHOSTS, "/home/user/known_hosts");
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curl_easy_perform(curl);
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}
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.fi
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.SH AVAILABILITY
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Added in 7.19.6
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.SH RETURN VALUE
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Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
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.SH "SEE ALSO"
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.BR CURLOPT_SSH_KEYDATA "(3), " CURLOPT_SSH_KNOWNHOSTS "(3), "
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