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kex: Use ssh_known_hosts_get_algorithms()

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Signed-off-by: Andreas Schneider <asn@cryptomilk.org>
This commit is contained in:
Andreas Schneider
2018-07-03 08:19:14 +02:00
parent 83a46c7756
commit 539d7ba249
2 changed files with 64 additions and 62 deletions
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89
src/kex.c
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@@ -36,6 +36,7 @@
#include "libssh/string.h"
#include "libssh/curve25519.h"
#include "libssh/knownhosts.h"
#include "libssh/misc.h"
#ifdef HAVE_LIBGCRYPT
# define BLOWFISH "blowfish-cbc,"
@@ -564,7 +565,8 @@ void ssh_list_kex(struct ssh_kex_struct *kex) {
* @returns a cstring containing a comma-separated list of hostkey methods.
* NULL if no method matches
*/
static char *ssh_client_select_hostkeys(ssh_session session){
static char *ssh_client_select_hostkeys(ssh_session session)
{
char methods_buffer[128]={0};
static const char *preferred_hostkeys[] = {
"ssh-ed25519",
@@ -577,42 +579,65 @@ static char *ssh_client_select_hostkeys(ssh_session session){
#endif
NULL
};
char **methods;
int i,j;
int needcoma=0;
struct ssh_list *algo_list = NULL;
struct ssh_iterator *it = NULL;
size_t algo_count;
int needcomma = 0;
int i;
methods = ssh_knownhosts_algorithms(session);
if (methods == NULL || methods[0] == NULL){
SAFE_FREE(methods);
return NULL;
}
algo_list = ssh_known_hosts_get_algorithms(session);
if (algo_list == NULL) {
return NULL;
}
for (i=0;preferred_hostkeys[i] != NULL; ++i){
for (j=0; methods[j] != NULL; ++j){
if(strcmp(preferred_hostkeys[i], methods[j]) == 0){
if (ssh_verify_existing_algo(SSH_HOSTKEYS, methods[j])){
if(needcoma)
strncat(methods_buffer,",",sizeof(methods_buffer)-strlen(methods_buffer)-1);
strncat(methods_buffer, methods[j], sizeof(methods_buffer)-strlen(methods_buffer)-1);
needcoma = 1;
}
}
}
}
for(i=0;methods[i]!= NULL; ++i){
SAFE_FREE(methods[i]);
}
SAFE_FREE(methods);
algo_count = ssh_list_count(algo_list);
if (algo_count == 0) {
ssh_list_free(algo_list);
return NULL;
}
if(strlen(methods_buffer) > 0){
SSH_LOG(SSH_LOG_DEBUG, "Changing host key method to \"%s\"", methods_buffer);
return strdup(methods_buffer);
} else {
SSH_LOG(SSH_LOG_DEBUG, "No supported kex method for existing key in known_hosts file");
return NULL;
}
for (i = 0; preferred_hostkeys[i] != NULL; ++i) {
for (it = ssh_list_get_iterator(algo_list);
it != NULL;
it = ssh_list_get_iterator(algo_list)) {
const char *algo = ssh_iterator_value(const char *, it);
int cmp;
int ok;
cmp = strcmp(preferred_hostkeys[i], algo);
if (cmp == 0) {
ok = ssh_verify_existing_algo(SSH_HOSTKEYS, algo);
if (ok) {
if (needcomma) {
strncat(methods_buffer,
",",
sizeof(methods_buffer) - strlen(methods_buffer) - 1);
}
strncat(methods_buffer,
algo,
sizeof(methods_buffer) - strlen(methods_buffer) - 1);
needcomma = 1;
}
}
ssh_list_remove(algo_list, it);
}
}
ssh_list_free(algo_list);
if (strlen(methods_buffer) == 0) {
SSH_LOG(SSH_LOG_DEBUG,
"No supported kex method for existing key in known_hosts file");
return NULL;
}
SSH_LOG(SSH_LOG_DEBUG,
"Changing host key method to \"%s\"",
methods_buffer);
return strdup(methods_buffer);
}
/**
* @brief sets the key exchange parameters to be sent to the server,
* in function of the options and available methods.