I'm now looking at this patch and didn't see any old discussion on why
this was not accepted Gary besides not finding it on the Pycurl list.
I apologize it has taking this long for someone to get back to you.

A couple of things. I'm not a fan of having base64_encode in here, it
just quite frankly does not belong in this module. That's a gripe of a
different sort at this point.

The const below needs cleaning up i've added corrections via + but the
patch will need to be resubmitted against the sourceforge cvs branch
of PyCurl. Otherwise I'd like to put this into the branch of pycurl
i'm working on here http://github.com/christophwarner/PyCurl/tree/2010
After some testing and reorganization I will commit.

-const curl_sshkeycallback sshkey_cb = sshkey_callback;
+const curl_sshkey_callback sshkey_cb = sshkey_callback;

Index: src/pycurl.c

===================================================================
--- src/pycurl.c.orig
+++ src/pycurl.c
@@ -156,6 +156,7 @@ typedef struct {
     PyObject *debug_cb;
     PyObject *ioctl_cb;
     PyObject *opensocket_cb;
+ PyObject *sshkey_cb;
     /* file objects */
     PyObject *readdata_fp;
     PyObject *writedata_fp;
@@ -734,6 +735,7 @@ util_curl_new(void)
     self->debug_cb = NULL;
     self->ioctl_cb = NULL;
     self->opensocket_cb = NULL;
+ self->sshkey_cb = NULL;

     /* Set file object pointers to NULL by default */
     self->readdata_fp = NULL;
@@ -845,6 +847,7 @@ util_curl_xdecref(CurlObject *self, int
         ZAP(self->pro_cb);
         ZAP(self->debug_cb);
         ZAP(self->ioctl_cb);
+ ZAP(self->sshkey_cb);
     }

     if (flags & 8) {
@@ -994,6 +997,7 @@ do_curl_traverse(CurlObject *self, visit
     VISIT(self->pro_cb);
     VISIT(self->debug_cb);
     VISIT(self->ioctl_cb);
+ VISIT(self->sshkey_cb);

     VISIT(self->readdata_fp);
     VISIT(self->writedata_fp);
@@ -1317,6 +1321,139 @@ verbose_error:
     goto silent_error;
 }

+static const char table64[]=
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+static char *
+base64_encode(const char *inputbuff, size_t insize)
+{
+ unsigned char ibuf[3];
+ unsigned char obuf[4];
+ int i;
+ int inputparts;
+ char *output;
+ char *base64data;
+
+ const char *indata = inputbuff;
+
+ if(0 == insize)
+ insize = strlen(indata);
+
+ base64data = output = malloc(insize*4/3+4);
+ if(NULL == output)
+ return NULL;
+
+ while(insize > 0) {
+ for (i = inputparts = 0; i < 3; i++) {
+ if(insize > 0) {
+ inputparts++;
+ ibuf[i] = *indata;
+ indata++;
+ insize--;
+ }
+ else
+ ibuf[i] = 0;
+ }
+
+ obuf[0] = (unsigned char) ((ibuf[0] & 0xFC) >> 2);
+ obuf[1] = (unsigned char) (((ibuf[0] & 0x03) << 4) | \
+ ((ibuf[1] & 0xF0) >> 4));
+ obuf[2] = (unsigned char) (((ibuf[1] & 0x0F) << 2) | \
+ ((ibuf[2] & 0xC0) >> 6));
+ obuf[3] = (unsigned char) (ibuf[2] & 0x3F);
+
+ switch(inputparts) {
+ case 1: /* only one byte read */
+ snprintf(output, 5, "%c%c==",
+ table64[obuf[0]],
+ table64[obuf[1]]);
+ break;
+ case 2: /* two bytes read */
+ snprintf(output, 5, "%c%c%c=",
+ table64[obuf[0]],
+ table64[obuf[1]],
+ table64[obuf[2]]);
+ break;
+ default:
+ snprintf(output, 5, "%c%c%c%c",
+ table64[obuf[0]],
+ table64[obuf[1]],
+ table64[obuf[2]],
+ table64[obuf[3]] );
+ break;
+ }
+ output += 4;
+ }
+ *output=0;
+
+ return base64data; /* return the length of the new data */
+}
+
+static int
+sshkey_callback (CURL *handle, const struct curl_khkey *knownkey,
+ const struct curl_khkey *foundkey, enum curl_khmatch match,
+ void *clientp)
+{
+ PyObject *arglist;
+ CurlObject *self;
+ PyThreadState *tmp_state;
+ PyObject *result = NULL;
+ int ret = CURLKHSTAT_REJECT; /* assume error */
+ char *knownkey_base64, *foundkey_base64;
+
+ UNUSED(handle);
+
+ /* acquire thread */
+ self = (CurlObject *)clientp;
+ tmp_state = get_thread_state(self);
+ if (tmp_state == NULL)
+ return ret;
+ PyEval_AcquireThread(tmp_state);
+
+ /* check args */
+ if (self->sshkey_cb == NULL)
+ goto silent_error;
+ knownkey_base64 = knownkey->len
+ ? base64_encode(knownkey->key, knownkey->len)
+ : strdup(knownkey->key);
+ foundkey_base64 = foundkey->len
+ ? base64_encode(foundkey->key, foundkey->len)
+ : strdup(foundkey->key);
+
+ /* run callback */
+ arglist = Py_BuildValue("((si)(si)i)",
+ knownkey_base64, knownkey->keytype,
+ foundkey_base64, foundkey->keytype,
+ match);
+
+ /* Py_BuildValue copies strings, so we can free the originals */
+ free (knownkey_base64);
+ free (foundkey_base64);
+
+ if (arglist == NULL)
+ goto verbose_error;
+ result = PyEval_CallObject(self->sshkey_cb, arglist);
+ Py_DECREF(arglist);
+ if (result == NULL)
+ goto verbose_error;
+
+ /* handle result */
+ if (PyInt_Check(result)) {
+ ret = (int) PyInt_AsLong(result);
+ if (ret >= CURLKHSTAT_LAST || ret < 0) {
+ PyErr_SetString(ErrorObject, "sshkey callback returned
invalid value");
+ goto verbose_error;
+ }
+ }
+
+silent_error:
+ Py_XDECREF(result);
+ PyEval_ReleaseThread(tmp_state);
+ return ret;
+verbose_error:
+ PyErr_Print();
+ goto silent_error;
+}

 static int
 debug_callback(CURL *curlobj, curl_infotype type,
@@ -1621,6 +1758,7 @@ do_curl_setopt(CurlObject *self, PyObjec
         case CURLOPT_USERAGENT:
         case CURLOPT_USERPWD:
         case CURLOPT_FTP_ALTERNATIVE_TO_USER:
+ case CURLOPT_SSH_KNOWNHOSTS:
         case CURLOPT_SSH_PUBLIC_KEYFILE:
         case CURLOPT_SSH_PRIVATE_KEYFILE:
         case CURLOPT_COPYPOSTFIELDS:
@@ -2017,7 +2155,8 @@ do_curl_setopt(CurlObject *self, PyObjec
         const curl_progress_callback pro_cb = progress_callback;
         const curl_debug_callback debug_cb = debug_callback;
         const curl_ioctl_callback ioctl_cb = ioctl_callback;
- const curl_opensocket_callback opensocket_cb = opensocket_callback;
+ const curl_opensocket_callback opensocket_cb = opensocket_callback;
+ const curl_sshkeycallback sshkey_cb = sshkey_callback;

         switch(option) {
         case CURLOPT_WRITEFUNCTION:
@@ -2075,7 +2214,13 @@ do_curl_setopt(CurlObject *self, PyObjec
             curl_easy_setopt(self->handle,
CURLOPT_OPENSOCKETFUNCTION, opensocket_cb);
             curl_easy_setopt(self->handle, CURLOPT_OPENSOCKETDATA, self);
             break;
-
+ case CURLOPT_SSH_KEYFUNCTION:
+ Py_INCREF(obj);
+ ZAP(self->sshkey_cb);
+ self->sshkey_cb = obj;
+ curl_easy_setopt(self->handle, CURLOPT_SSH_KEYFUNCTION, sshkey_cb);
+ curl_easy_setopt(self->handle, CURLOPT_SSH_KEYDATA, self);
+ break;
         default:
             /* None of the function options were recognized, throw exception */
             PyErr_SetString(PyExc_TypeError, "functions are not
supported for this option");
@@ -2385,7 +2530,6 @@ silent_error:
 verbose_error:
     PyErr_Print();
     goto silent_error;
- return 0;
 }

@@ -3480,6 +3624,18 @@ initpycurl(void)
     insint_c(d, "INFOTYPE_SSL_DATA_IN", CURLINFO_SSL_DATA_IN);
     insint_c(d, "INFOTYPE_SSL_DATA_OUT", CURLINFO_SSL_DATA_OUT);

+ /* curl_khkey enum type: the type of key passed to SSH_KEYFUNCTION */
+ insint_c(d, "KHTYPE_UNKNOWN", CURLKHTYPE_UNKNOWN);
+ insint_c(d, "KHTYPE_RSA1", CURLKHTYPE_RSA1);
+ insint_c(d, "KHTYPE_RSA", CURLKHTYPE_RSA);
+ insint_c(d, "KHTYPE_DSS", CURLKHTYPE_DSS);
+
+ /* constants for sshkey function callback return values */
+ insint_c(d, "KHSTAT_FINE_ADD_TO_FILE", CURLKHSTAT_FINE_ADD_TO_FILE);
+ insint_c(d, "KHSTAT_FINE", CURLKHSTAT_FINE);
+ insint_c(d, "KHSTAT_REJECT", CURLKHSTAT_REJECT);
+ insint_c(d, "KHSTAT_DEFER", CURLKHSTAT_DEFER);
+
     /* CURLcode: error codes */
     insint_c(d, "E_OK", CURLE_OK);
     insint_c(d, "E_UNSUPPORTED_PROTOCOL", CURLE_UNSUPPORTED_PROTOCOL);
@@ -3718,6 +3874,9 @@ initpycurl(void)
     insint_c(d, "MAX_RECV_SPEED_LARGE", CURLOPT_MAX_RECV_SPEED_LARGE);
     insint_c(d, "SSL_SESSIONID_CACHE", CURLOPT_SSL_SESSIONID_CACHE);
     insint_c(d, "SSH_AUTH_TYPES", CURLOPT_SSH_AUTH_TYPES);
+ insint_c(d, "SSH_KEYDATA", CURLOPT_SSH_KEYDATA);
+ insint_c(d, "SSH_KEYFUNCTION", CURLOPT_SSH_KEYFUNCTION);
+ insint_c(d, "SSH_KNOWNHOSTS", CURLOPT_SSH_KNOWNHOSTS);
     insint_c(d, "SSH_PUBLIC_KEYFILE", CURLOPT_SSH_PUBLIC_KEYFILE);
     insint_c(d, "SSH_PRIVATE_KEYFILE", CURLOPT_SSH_PRIVATE_KEYFILE);
     insint_c(d, "FTP_SSL_CCC", CURLOPT_FTP_SSL_CCC);

--
Christopher Warner
http://cwarner.kernelcode.com
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