diff options
| -rw-r--r-- | src/kex.c | 33 |
1 files changed, 30 insertions, 3 deletions
@@ -26,6 +26,7 @@ #include <string.h> #include <stdlib.h> #include <stdio.h> +#include <stdbool.h> #include "libssh/priv.h" #include "libssh/buffer.h" @@ -608,6 +609,8 @@ void ssh_list_kex(struct ssh_kex_struct *kex) { static char *ssh_client_select_hostkeys(ssh_session session) { char methods_buffer[128]={0}; + char tail_buffer[128]={0}; + char *new_hostkeys = NULL; static const char *preferred_hostkeys[] = { "ssh-ed25519", "ecdsa-sha2-nistp521", @@ -623,7 +626,7 @@ static char *ssh_client_select_hostkeys(ssh_session session) struct ssh_iterator *it = NULL; size_t algo_count; int needcomma = 0; - int i; + size_t i, len; algo_list = ssh_known_hosts_get_algorithms(session); if (algo_list == NULL) { @@ -637,6 +640,8 @@ static char *ssh_client_select_hostkeys(ssh_session session) } for (i = 0; preferred_hostkeys[i] != NULL; ++i) { + bool found = false; + for (it = ssh_list_get_iterator(algo_list); it != NULL; it = it->next) { @@ -657,9 +662,19 @@ static char *ssh_client_select_hostkeys(ssh_session session) algo, sizeof(methods_buffer) - strlen(methods_buffer) - 1); needcomma = 1; + found = true; } } } + /* Collect the rest of the algorithms in other buffer, that will + * follow the preferred buffer. This will signalize all the algorithms + * we are willing to accept. + */ + if (!found) { + snprintf(tail_buffer + strlen(tail_buffer), + sizeof(tail_buffer) - strlen(tail_buffer), + ",%s", preferred_hostkeys[i]); + } } ssh_list_free(algo_list); @@ -669,11 +684,23 @@ static char *ssh_client_select_hostkeys(ssh_session session) return NULL; } + /* Append the supported list to the preferred. + * The length is maximum 128 + 128 + 1, which will not overflow + */ + len = strlen(methods_buffer) + strlen(tail_buffer) + 1; + new_hostkeys = malloc(len); + if (new_hostkeys == NULL) { + ssh_set_error_oom(session); + return NULL; + } + snprintf(new_hostkeys, len, + "%s%s", methods_buffer, tail_buffer); + SSH_LOG(SSH_LOG_DEBUG, "Changing host key method to \"%s\"", - methods_buffer); + new_hostkeys); - return strdup(methods_buffer); + return new_hostkeys; } /** |