/**************************************************************************//**
* Get a string value from supplied JSON by matching the key.
*
* As the structure of the metadata we're looking at is pretty straightforward
* we don't do anything complex (a la XPath) to extract nested keys with the
* same leaf name, for example. Simply walk the structure until we find a
* string with the correct value.
*
* @param[in] json_string The string which contains the JSON and has already
* been parsed.
* @param[in] tokens The tokens which the JSON parser found in the JSON.
* @param[in] json_token_count How many tokens were found.
* @param[in] key The key we're looking for.
* @param[out] value The string we found at @p key.
*
* @returns Status code
* @retval EVEL_SUCCESS On success - contents of @p value updated.
* @retval EVEL_JSON_KEY_NOT_FOUND Key not found - @p value not updated.
* @retval EVEL_BAD_JSON Parser hit unexpected data - @p value not
* updated.
*****************************************************************************/
static EVEL_ERR_CODES json_get_string(const char * json_string,
const jsmntok_t * tokens,
int json_token_count,
const char * key,
char * value)
{
EVEL_ERR_CODES rc = EVEL_JSON_KEY_NOT_FOUND;
int token_num = 0;
int token_len = 0;
EVEL_ENTER();
/***************************************************************************/
/* Check assumptions. */
/***************************************************************************/
assert(json_string != NULL);
assert(tokens != NULL);
assert(json_token_count >= 0);
assert(key != NULL);
assert(value != NULL);
for (token_num = 0; token_num < json_token_count; token_num++)
{
switch(tokens[token_num].type)
{
case JSMN_OBJECT:
EVEL_DEBUG("Skipping object");
break;
case JSMN_ARRAY:
EVEL_DEBUG("Skipping array");
break;
case JSMN_STRING:
/***********************************************************************/
/* This is a string, so may be what we want. Compare keys. */
/***********************************************************************/
if (jsoneq(json_string, &tokens[token_num], key) == 0)
{
token_len = tokens[token_num + 1].end - tokens[token_num + 1].start;
EVEL_DEBUG("Token %d len %d matches at %d to %d", token_num,
tokens[token_num + 1].start,
tokens[token_num + 1].end);
strncpy(value, json_string + tokens[token_num + 1].start, token_len);
value[token_len] = '\0';
EVEL_DEBUG("Extracted key: \"%s\" Value: \"%s\"", key, value);
rc = EVEL_SUCCESS;
goto exit_label;
}
else
{
EVEL_DEBUG("String key did not match");
}
/***********************************************************************/
/* Step over the value, whether we used it or not. */
/***********************************************************************/
token_num++;
break;
case JSMN_PRIMITIVE:
EVEL_INFO("Skipping primitive");
break;
case JSMN_UNDEFINED:
default:
rc = EVEL_BAD_JSON_FORMAT;
EVEL_ERROR("Unexpected JSON format at token %d (%d)",
token_num,
tokens[token_num].type);
goto exit_label;
}
}
exit_label:
EVEL_EXIT();
return rc;
}
/**************************************************************************//**
* Download metadata from the OpenStack metadata service.
*
* @param verbosity Controls whether to generate debug to stdout. Zero:
* none. Non-zero: generate debug.
* @returns Status code
* @retval EVEL_SUCCESS On success
* @retval ::EVEL_ERR_CODES On failure.
*****************************************************************************/
EVEL_ERR_CODES openstack_metadata(int verbosity)
{
int rc = EVEL_SUCCESS;
CURLcode curl_rc = CURLE_OK;
CURL * curl_handle = NULL;
MEMORY_CHUNK rx_chunk;
char curl_err_string[CURL_ERROR_SIZE] = "<NULL>";
jsmn_parser json_parser;
jsmntok_t tokens[MAX_METADATA_TOKENS];
int json_token_count = 0;
EVEL_ENTER();
/***************************************************************************/
/* Initialize dummy values for the metadata - needed for test */
/* environments. */
/***************************************************************************/
strncpy(vm_uuid,
"Dummy VM UUID - No Metadata available",
MAX_METADATA_STRING);
strncpy(vm_name,
"Dummy VM name - No Metadata available",
MAX_METADATA_STRING);
/***************************************************************************/
/* Get a curl handle which we'll use for accessing the metadata service. */
/***************************************************************************/
curl_handle = curl_easy_init();
if (curl_handle == NULL)
{
rc = EVEL_CURL_LIBRARY_FAIL;
EVEL_ERROR("Failed to get libcurl handle");
goto exit_label;
}
/***************************************************************************/
/* Prime the library to give friendly error codes. */
/***************************************************************************/
curl_rc = curl_easy_setopt(curl_handle,
CURLOPT_ERRORBUFFER,
curl_err_string);
if (curl_rc != CURLE_OK)
{
rc = EVEL_CURL_LIBRARY_FAIL;
EVEL_ERROR("Failed to initialize libcurl to provide friendly errors. "
"Error code=%d", curl_rc);
goto exit_label;
}
/***************************************************************************/
/* Set the URL for the metadata API. */
/***************************************************************************/
curl_rc = curl_easy_setopt(curl_handle, CURLOPT_URL, OPENSTACK_METADATA_URL);
if (curl_rc != CURLE_OK)
{
rc = EVEL_CURL_LIBRARY_FAIL;
EVEL_ERROR("Failed to initialize libcurl with the API URL. "
"Error code=%d (%s)", curl_rc, curl_err_string);
goto exit_label;
}
/***************************************************************************/
/* send all data to this function. */
/***************************************************************************/
curl_rc = curl_easy_setopt(curl_handle,
CURLOPT_WRITEFUNCTION,
evel_write_callback);
if (curl_rc != CURLE_OK)
{
rc = EVEL_CURL_LIBRARY_FAIL;
EVEL_ERROR("Failed to initialize libcurl with the write callback. "
"Error code=%d (%s)", curl_rc, curl_err_string);
goto exit_label;
}
/***************************************************************************/
/* some servers don't like requests that are made without a user-agent */
/* field, so we provide one. */
/***************************************************************************/
curl_rc = curl_easy_setopt(curl_handle,
CURLOPT_USERAGENT,
"libcurl-agent/1.0");
if (curl_rc != CURLE_OK)
{
rc = EVEL_CURL_LIBRARY_FAIL;
EVEL_ERROR("Failed to initialize libcurl to upload. Error code=%d (%s)",
curl_rc, curl_err_string);
goto exit_label;
}
/***************************************************************************/
/* Set the timeout for the operation. */
/***************************************************************************/
curl_rc = curl_easy_setopt(curl_handle,
CURLOPT_TIMEOUT,
OPENSTACK_METADATA_TIMEOUT);
if (curl_rc != CURLE_OK)
{
rc = EVEL_NO_METADATA;
EVEL_ERROR("Failed to initialize libcurl to set timeout. "
"Error code=%d (%s)", curl_rc, curl_err_string);
goto exit_label;
}
/***************************************************************************/
/* Create the memory chunk to be used for the response to the post. The */
/* will be realloced. */
/***************************************************************************/
rx_chunk.memory = malloc(1);
assert(rx_chunk.memory != NULL);
rx_chunk.size = 0;
/***************************************************************************/
/* Point to the data to be received. */
/***************************************************************************/
curl_rc = curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&rx_chunk);
if (curl_rc != CURLE_OK)
{
rc = EVEL_CURL_LIBRARY_FAIL;
EVEL_ERROR("Failed to initialize libcurl to receive metadata. "
"Error code=%d (%s)", curl_rc, curl_err_string);
goto exit_label;
}
EVEL_DEBUG("Initialized data to receive");
/***************************************************************************/
/* If running in verbose mode generate more output. */
/***************************************************************************/
if (verbosity > 0)
{
curl_rc = curl_easy_setopt(curl_handle, CURLOPT_VERBOSE, 1L);
if (curl_rc != CURLE_OK)
{
rc = EVEL_CURL_LIBRARY_FAIL;
log_error_state("Failed to initialize libcurl to be verbose. "
"Error code=%d", curl_rc);
goto exit_label;
}
}
/***************************************************************************/
/* Now run off and do what you've been told! */
/***************************************************************************/
curl_rc = curl_easy_perform(curl_handle);
if (curl_rc != CURLE_OK)
{
rc = EVEL_CURL_LIBRARY_FAIL;
EVEL_ERROR("Failed to transfer the data from metadata service. "
"Error code=%d (%s)", curl_rc, curl_err_string);
}
else
{
/*************************************************************************/
/* We have some metadata available, so break it out into tokens. */
/*************************************************************************/
EVEL_DEBUG("Received metadata size = %d", rx_chunk.size);
EVEL_INFO("Received metadata = %s", rx_chunk.memory);
jsmn_init(&json_parser);
json_token_count = jsmn_parse(&json_parser,
rx_chunk.memory, rx_chunk.size,
tokens, MAX_METADATA_TOKENS);
/*************************************************************************/
/* Check that we parsed some data and that the top level is as expected. */
/*************************************************************************/
if (json_token_count < 0 || tokens[0].type != JSMN_OBJECT)
{
rc = EVEL_BAD_METADATA;
EVEL_ERROR("Failed to parse received JSON OpenStack metadata. "
"Error code=%d", json_token_count);
goto exit_label;
}
else
{
EVEL_DEBUG("Extracted %d tokens from the JSON OpenStack metadata. ",
json_token_count);
}
/*************************************************************************/
/* Find the keys we want from the metadata. */
/*************************************************************************/
if (json_get_string(rx_chunk.memory,
tokens,
json_token_count,
"uuid",
vm_uuid) != EVEL_SUCCESS)
{
rc = EVEL_BAD_METADATA;
EVEL_ERROR("Failed to extract UUID from OpenStack metadata");
}
else
{
EVEL_DEBUG("UUID: %s", vm_uuid);
}
if (json_get_string(rx_chunk.memory,
tokens,
json_token_count,
"name",
vm_name) != EVEL_SUCCESS)
{
rc = EVEL_BAD_METADATA;
EVEL_ERROR("Failed to extract VM Name from OpenStack metadata");
}
else
{
EVEL_DEBUG("VM Name: %s", vm_name);
}
}
exit_label:
/***************************************************************************/
/* Shut down the cURL library in a tidy manner. */
/***************************************************************************/
if (curl_handle != NULL)
{
curl_easy_cleanup(curl_handle);
curl_handle = NULL;
}
free(rx_chunk.memory);
EVEL_EXIT();
return rc;
}
/**************************************************************************//**
* Get a top-level string value from supplied JSON by matching the key.
*
* Unlike json_get_string, this only returns a value that is in the top-level
* JSON object.
*
* @param[in] json_string The string which contains the JSON and has already
* been parsed.
* @param[in] tokens The tokens which the JSON parser found in the JSON.
* @param[in] json_token_count How many tokens were found.
* @param[in] key The key we're looking for.
* @param[out] value The string we found at @p key.
*
* @returns Status code
* @retval EVEL_SUCCESS On success - contents of @p value updated.
* @retval EVEL_JSON_KEY_NOT_FOUND Key not found - @p value not updated.
* @retval EVEL_BAD_JSON Parser hit unexpected data - @p value not
* updated.
*****************************************************************************/
static EVEL_ERR_CODES json_get_top_level_string(const char * json_string,
const jsmntok_t * tokens,
int json_token_count,
const char * key,
char * value)
{
EVEL_ERR_CODES rc = EVEL_JSON_KEY_NOT_FOUND;
int token_num = 0;
int token_len = 0;
int bracket_count = 0;
int string_index = 0;
int increment = 0;
EVEL_ENTER();
/***************************************************************************/
/* Check assumptions. */
/***************************************************************************/
assert(json_string != NULL);
assert(tokens != NULL);
assert(json_token_count >= 0);
assert(key != NULL);
assert(value != NULL);
for (token_num = 0; token_num < json_token_count; token_num++)
{
switch(tokens[token_num].type)
{
case JSMN_OBJECT:
EVEL_DEBUG("Skipping object");
break;
case JSMN_ARRAY:
EVEL_DEBUG("Skipping array");
break;
case JSMN_STRING:
/***********************************************************************/
/* This is a string, so may be what we want. Compare keys. */
/***********************************************************************/
if (jsoneq(json_string, &tokens[token_num], key) == 0)
{
/*********************************************************************/
/* Count the difference in the number of opening and closing */
/* brackets up to this token. This needs to be 1 for a top-level */
/* string. Let's just hope we don't have any strings containing */
/* brackets. */
/*********************************************************************/
increment = ((string_index < tokens[token_num].start) ? 1 : -1);
while (string_index != tokens[token_num].start)
{
if (json_string[string_index] == '{')
{
bracket_count += increment;
}
else if (json_string[string_index] == '}')
{
bracket_count -= increment;
}
string_index += increment;
}
if (bracket_count == 1)
{
token_len = tokens[token_num + 1].end - tokens[token_num + 1].start;
EVEL_DEBUG("Token %d len %d matches at top level at %d to %d",
token_num,
tokens[token_num + 1].start,
tokens[token_num + 1].end);
strncpy(value, json_string + tokens[token_num + 1].start, token_len);
value[token_len] = '\0';
EVEL_DEBUG("Extracted key: \"%s\" Value: \"%s\"", key, value);
rc = EVEL_SUCCESS;
goto exit_label;
}
else
{
EVEL_DEBUG("String key did match, but not at top level");
}
}
else
{
EVEL_DEBUG("String key did not match");
}
/***********************************************************************/
/* Step over the value, whether we used it or not. */
/***********************************************************************/
token_num++;
break;
case JSMN_PRIMITIVE:
EVEL_INFO("Skipping primitive");
break;
case JSMN_UNDEFINED:
default:
rc = EVEL_BAD_JSON_FORMAT;
EVEL_ERROR("Unexpected JSON format at token %d (%d)",
token_num,
tokens[token_num].type);
goto exit_label;
}
}
exit_label:
EVEL_EXIT();
return rc;
}
