Adding expand-path@openssh.com extension for client

Signed-off-by: anshul agrawal <anshulagrawal2902@gmail.com>
Reviewed-by: Sahana Prasad <sahana@redhat.com>
Reviewed-by: Eshan Kelkar <eshankelkar@galorithm.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>

include/libssh/sftp.h

@@ -897,6 +897,19 @@ LIBSSH_API char *sftp_canonicalize_path(sftp_session sftp, const char *path);
  */
 LIBSSH_API int sftp_server_version(sftp_session sftp);
 
+/**
+ * @brief Canonicalize path using expand-path@openssh.com extension
+ *
+ * @param sftp          The sftp session handle.
+ *
+ * @param path          The path to be canonicalized.
+ *
+ * @return              A pointer to the newly allocated canonicalized path,
+ *                      NULL on error. The caller needs to free the memory
+ *                      using ssh_string_free_char().
+ */
+LIBSSH_API char *sftp_expand_path(sftp_session sftp, const char *path);
+
 #ifdef WITH_SERVER
 /**
  * @brief Create a new sftp server session.

src/sftp.c

@@ -3744,4 +3744,98 @@ sftp_attributes sftp_fstat(sftp_file file)
     return NULL;
 }
 
+char *sftp_expand_path(sftp_session sftp, const char *path)
+{
+    sftp_status_message status = NULL;
+    sftp_message msg = NULL;
+    ssh_buffer buffer = NULL;
+    uint32_t id;
+    int rc;
+
+    if (sftp == NULL) {
+        return NULL;
+    }
+
+    if (path == NULL) {
+        ssh_set_error(sftp->session,
+                      SSH_FATAL,
+                      "NULL received as an argument instead of the path to expand");
+        sftp_set_error(sftp, SSH_FX_FAILURE);
+        return NULL;
+    }
+
+    buffer = ssh_buffer_new();
+    if (buffer == NULL) {
+        ssh_set_error_oom(sftp->session);
+        sftp_set_error(sftp, SSH_FX_FAILURE);
+        return NULL;
+    }
+
+    id = sftp_get_new_id(sftp);
+
+    rc = ssh_buffer_pack(buffer,
+                         "dss",
+                         id,
+                         "expand-path@openssh.com",
+                         path);
+    if (rc != SSH_OK) {
+        ssh_set_error_oom(sftp->session);
+        SSH_BUFFER_FREE(buffer);
+        sftp_set_error(sftp, SSH_FX_FAILURE);
+        return NULL;
+    }
+
+    rc = sftp_packet_write(sftp, SSH_FXP_EXTENDED, buffer);
+    SSH_BUFFER_FREE(buffer);
+    if (rc < 0) {
+        return NULL;
+    }
+
+    while (msg == NULL) {
+        rc = sftp_read_and_dispatch(sftp);
+        if (rc < 0) {
+            return NULL;
+        }
+        msg = sftp_dequeue(sftp, id);
+    }
+
+    if (msg->packet_type == SSH_FXP_NAME) {
+        uint32_t ignored = 0;
+        char *cname = NULL;
+
+        rc = ssh_buffer_unpack(msg->payload,
+                               "ds",
+                               &ignored,
+                               &cname);
+        sftp_message_free(msg);
+        if (rc != SSH_OK) {
+            ssh_set_error(sftp->session,
+                          SSH_ERROR,
+                          "Failed to parse expanded path");
+            sftp_set_error(sftp, SSH_FX_FAILURE);
+            return NULL;
+        }
+
+        return cname;
+    } else if (msg->packet_type == SSH_FXP_STATUS) {
+        status = parse_status_msg(msg);
+        sftp_message_free(msg);
+        if (status == NULL) {
+            return NULL;
+        }
+        sftp_set_error(sftp, status->status);
+        ssh_set_error(sftp->session, SSH_REQUEST_DENIED,
+                      "SFTP server: %s", status->errormsg);
+        status_msg_free(status);
+    } else {
+        ssh_set_error(sftp->session, SSH_FATAL,
+                      "Received message %d when attempting to expand path",
+                      msg->packet_type);
+        sftp_message_free(msg);
+        sftp_set_error(sftp, SSH_FX_BAD_MESSAGE);
+    }
+
+    return NULL;
+}
+
 #endif /* WITH_SFTP */

tests/client/CMakeLists.txt

@@ -53,6 +53,7 @@ if (WITH_SFTP)
         torture_sftp_hardlink
         torture_sftp_limits
         torture_sftp_rename
+        torture_sftp_expand_path
         ${SFTP_BENCHMARK_TESTS})
 endif (WITH_SFTP)
 

tests/client/torture_sftp_expand_path.c

@@ -0,0 +1,125 @@
+#include "config.h"
+
+#define LIBSSH_STATIC
+
+#include "torture.h"
+#include "sftp.c"
+
+#include <sys/types.h>
+#include <pwd.h>
+#include <errno.h>
+
+static int sshd_setup(void **state)
+{
+    torture_setup_sshd_server(state, false);
+
+    return 0;
+}
+
+static int sshd_teardown(void **state)
+{
+    torture_teardown_sshd_server(state);
+
+    return 0;
+}
+
+static int session_setup(void **state)
+{
+    struct torture_state *s = *state;
+    struct passwd *pwd = NULL;
+    int rc;
+
+    pwd = getpwnam("bob");
+    assert_non_null(pwd);
+
+    rc = setuid(pwd->pw_uid);
+    assert_return_code(rc, errno);
+
+    s->ssh.session = torture_ssh_session(s,
+                                         TORTURE_SSH_SERVER,
+                                         NULL,
+                                         TORTURE_SSH_USER_ALICE,
+                                         NULL);
+    assert_non_null(s->ssh.session);
+
+    s->ssh.tsftp = torture_sftp_session(s->ssh.session);
+    assert_non_null(s->ssh.tsftp);
+
+    return 0;
+}
+
+static int session_teardown(void **state)
+{
+    struct torture_state *s = *state;
+
+    torture_rmdirs(s->ssh.tsftp->testdir);
+    torture_sftp_close(s->ssh.tsftp);
+    ssh_disconnect(s->ssh.session);
+    ssh_free(s->ssh.session);
+
+    return 0;
+}
+
+static void torture_sftp_expand_path(void **state)
+{
+    struct torture_state *s = *state;
+    struct torture_sftp *t = s->ssh.tsftp;
+    struct passwd *pwd = NULL;
+    char *expanded_path = NULL;
+    int rc;
+
+    rc = sftp_extension_supported(t->sftp, "expand-path@openssh.com", "1");
+    if (rc == 0) {
+        skip();
+    }
+
+    pwd = getpwnam(TORTURE_SSH_USER_ALICE);
+    assert_non_null(pwd);
+
+    /* testing for a absolute path */
+    expanded_path = sftp_expand_path(t->sftp, "~/.");
+    assert_non_null(expanded_path);
+
+    assert_string_equal(expanded_path, pwd->pw_dir);
+
+    SSH_STRING_FREE_CHAR(expanded_path);
+
+    /* testing for a relative path */
+    expanded_path = sftp_expand_path(t->sftp, ".");
+    assert_non_null(expanded_path);
+
+    assert_string_equal(expanded_path, pwd->pw_dir);
+
+    SSH_STRING_FREE_CHAR(expanded_path);
+
+    /* passing a NULL sftp session */
+    expanded_path = sftp_expand_path(NULL, "~/.");
+    assert_null(expanded_path);
+
+    /* passing an invalid path */
+    expanded_path = sftp_expand_path(t->sftp, "/...//");
+    assert_null(expanded_path);
+
+    /* passing null path */
+    expanded_path = sftp_expand_path(t->sftp, NULL);
+    assert_null(expanded_path);
+}
+
+int torture_run_tests(void)
+{
+    int rc;
+    struct CMUnitTest tests[] = {
+        cmocka_unit_test_setup_teardown(torture_sftp_expand_path,
+                                        session_setup,
+                                        session_teardown)
+    };
+
+    ssh_init();
+
+    torture_filter_tests(tests);
+    rc = cmocka_run_group_tests(tests, sshd_setup, sshd_teardown);
+
+    ssh_finalize();
+
+    return rc;
+}