libssh: avoid options override by configuration files

Previously, options set explicitly through command line options could be
overridden by the configuration files parsed automatically when
ssh_connect() was called.

By calling ssh_options_parse_config() explicitly, the configuration
files are parsed before setting the options, avoiding the options
override.  Once the configuration files are parsed, the automatic
configuration parsing is not executed.

Fixes #4972
Closes #5283
Signed-off-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>

lib/vssh/libssh.c

@@ -2149,6 +2149,7 @@ static CURLcode myssh_connect(struct connectdata *conn, bool *done)
   CURLcode result;
   curl_socket_t sock = conn->sock[FIRSTSOCKET];
   struct Curl_easy *data = conn->data;
+  int rc;
 
   /* initialize per-handle data if not already */
   if(!data->req.protop)
@@ -2175,38 +2176,70 @@ static CURLcode myssh_connect(struct connectdata *conn, bool *done)
     return CURLE_FAILED_INIT;
   }
 
-  ssh_options_set(ssh->ssh_session, SSH_OPTIONS_FD, &sock);
+  rc = ssh_options_set(ssh->ssh_session, SSH_OPTIONS_HOST, conn->host.name);
+  if(rc != SSH_OK) {
+    failf(data, "Could not set remote host");
+    return CURLE_FAILED_INIT;
+  }
 
-  if(conn->user) {
+  rc = ssh_options_parse_config(ssh->ssh_session, NULL);
+  if(rc != SSH_OK) {
+    infof(data, "Could not parse SSH configuration files");
+    /* ignore */
+  }
+
+  rc = ssh_options_set(ssh->ssh_session, SSH_OPTIONS_FD, &sock);
+  if(rc != SSH_OK) {
+    failf(data, "Could not set socket");
+    return CURLE_FAILED_INIT;
+  }
+
+  if(conn->user && conn->user[0] != '\0') {
     infof(data, "User: %s\n", conn->user);
-    ssh_options_set(ssh->ssh_session, SSH_OPTIONS_USER, conn->user);
+    rc = ssh_options_set(ssh->ssh_session, SSH_OPTIONS_USER, conn->user);
+    if(rc != SSH_OK) {
+      failf(data, "Could not set user");
+      return CURLE_FAILED_INIT;
+    }
   }
 
   if(data->set.str[STRING_SSH_KNOWNHOSTS]) {
     infof(data, "Known hosts: %s\n", data->set.str[STRING_SSH_KNOWNHOSTS]);
-    ssh_options_set(ssh->ssh_session, SSH_OPTIONS_KNOWNHOSTS,
-                    data->set.str[STRING_SSH_KNOWNHOSTS]);
+    rc = ssh_options_set(ssh->ssh_session, SSH_OPTIONS_KNOWNHOSTS,
+                         data->set.str[STRING_SSH_KNOWNHOSTS]);
+    if(rc != SSH_OK) {
+      failf(data, "Could not set known hosts file path");
+      return CURLE_FAILED_INIT;
+    }
   }
 
-  ssh_options_set(ssh->ssh_session, SSH_OPTIONS_HOST, conn->host.name);
-  if(conn->remote_port)
-    ssh_options_set(ssh->ssh_session, SSH_OPTIONS_PORT,
-                    &conn->remote_port);
+  if(conn->remote_port) {
+    rc = ssh_options_set(ssh->ssh_session, SSH_OPTIONS_PORT,
+                         &conn->remote_port);
+    if(rc != SSH_OK) {
+      failf(data, "Could not set remote port");
+      return CURLE_FAILED_INIT;
+    }
+  }
 
   if(data->set.ssh_compression) {
-    ssh_options_set(ssh->ssh_session, SSH_OPTIONS_COMPRESSION,
-                    "zlib,zlib@openssh.com,none");
+    rc = ssh_options_set(ssh->ssh_session, SSH_OPTIONS_COMPRESSION,
+                         "zlib,zlib@openssh.com,none");
+    if(rc != SSH_OK) {
+      failf(data, "Could not set compression");
+      return CURLE_FAILED_INIT;
+    }
   }
 
   ssh->privkey = NULL;
   ssh->pubkey = NULL;
 
   if(data->set.str[STRING_SSH_PUBLIC_KEY]) {
-    int rc = ssh_pki_import_pubkey_file(data->set.str[STRING_SSH_PUBLIC_KEY],
-                                        &ssh->pubkey);
+    rc = ssh_pki_import_pubkey_file(data->set.str[STRING_SSH_PUBLIC_KEY],
+                                    &ssh->pubkey);
     if(rc != SSH_OK) {
       failf(data, "Could not load public key file");
-      /* ignore */
+      return CURLE_FAILED_INIT;
     }
   }