curl.c File Reference

#include "asterisk.h"
#include "asterisk/utils.h"
#include "asterisk/logger.h"
#include "curl.h"
#include "general.h"
#include "stir_shaken.h"
#include <curl/curl.h>
#include <sys/stat.h>

Include dependency graph for curl.c:

Go to the source code of this file.

Data Structures
struct	curl_cb_data

Macros
#define	GLOBAL_USERAGENT   "asterisk-libcurl-agent/1.0"
#define	MAX_HEADER_LENGTH   1023

Functions
static int	create_temp_file (const char *path, char **filename)
	Create a temporary file located at path. More...
struct curl_cb_data *	curl_cb_data_create (void)
	Allocate memory for a curl_cb_data struct. More...
void	curl_cb_data_free (struct curl_cb_data *data)
	Free a curl_cb_data struct. More...
char *	curl_cb_data_get_cache_control (const struct curl_cb_data *data)
	Get the cache_control field from a curl_cb_data struct. More...
char *	curl_cb_data_get_expires (const struct curl_cb_data *data)
	Get the expires field from a curl_cb_data struct. More...
static size_t	curl_header_callback (char *buffer, size_t size, size_t nitems, void *data)
	Called when a CURL request completes. More...
char *	curl_public_key (const char *public_cert_url, const char *path, struct curl_cb_data *data)
	CURL the public key from the provided URL to the specified path. More...
static CURL *	get_curl_instance (struct curl_cb_data *data)
	Prepare a CURL instance to use. More...

Macro Definition Documentation

GLOBAL_USERAGENT

#define GLOBAL_USERAGENT   "asterisk-libcurl-agent/1.0"

Definition at line 34 of file curl.c.

Referenced by get_curl_instance().

MAX_HEADER_LENGTH

#define MAX_HEADER_LENGTH   1023

Definition at line 31 of file curl.c.

Referenced by curl_header_callback().

Function Documentation

create_temp_file()

static int create_temp_file ( const char *  path, char **  filename  )

static

Create a temporary file located at path.

Note

This function assumes path does not end with a '/'

Parameters

path	The directory path to create the file in
filename	Function allocates memory and stores full filename (including path) here

Return values

-1	on failure
file	descriptor on success

Definition at line 164 of file curl.c.

References ast_asprintf, ast_free, ast_log, ast_mkdir(), LOG_ERROR, and LOG_NOTICE.

Referenced by curl_public_key().

{
   const char *template_name = "certXXXXXX";
   int fd;

   if (ast_asprintf(filename, "%s/%s", path, template_name) < 0) {
      ast_log(LOG_ERROR, "Failed to set up temporary file path for CURL\n");
      return -1;
   }

   ast_mkdir(path, 0644);

   if ((fd = mkstemp(*filename)) < 0) {
      ast_log(LOG_NOTICE, "Failed to create temporary file for CURL\n");
      ast_free(*filename);
      return -1;
   }

   return fd;
}

curl_cb_data_create()

struct curl_cb_data* curl_cb_data_create

(

void

)

Allocate memory for a curl_cb_data struct.

Note

This will need to be freed by the consumer using curl_cb_data_free

Return values

NULL	on failure
curl_cb_struct	on success

Definition at line 42 of file curl.c.

References ast_calloc.

Referenced by run_curl().

{
   struct curl_cb_data *data;

   data = ast_calloc(1, sizeof(*data));

   return data;
}

curl_cb_data_free()

void curl_cb_data_free

(

struct curl_cb_data *

data

)

Free a curl_cb_data struct.

Parameters

data	The curl_cb_data struct to free

Definition at line 51 of file curl.c.

References ast_free, curl_cb_data::cache_control, and curl_cb_data::expires.

Referenced by run_curl().

{
   if (!data) {
      return;
   }

   ast_free(data->cache_control);
   ast_free(data->expires);

   ast_free(data);
}

curl_cb_data_get_cache_control()

char* curl_cb_data_get_cache_control

(

const struct curl_cb_data *

data

)

Get the cache_control field from a curl_cb_data struct.

Parameters

data	The curl_cb_data

Return values

cache_control	on success
NULL	otherwise

Definition at line 63 of file curl.c.

References curl_cb_data::cache_control, and NULL.

Referenced by set_public_key_expiration().

{
   if (!data) {
      return NULL;
   }

   return data->cache_control;
}

curl_cb_data_get_expires()

char* curl_cb_data_get_expires

(

const struct curl_cb_data *

data

)

Get the expires field from a curl_cb_data struct.

Parameters

data	The curl_cb_data

Return values

expires	on success
NULL	otherwise

Definition at line 72 of file curl.c.

References curl_cb_data::expires, and NULL.

Referenced by set_public_key_expiration().

{
   if (!data) {
      return NULL;
   }

   return data->expires;
}

curl_header_callback()

static size_t curl_header_callback ( char *  buffer, size_t  size, size_t  nitems, void *  data  )

static

Called when a CURL request completes.

Parameters

data	The curl_cb_data structure to store expiration info

Definition at line 86 of file curl.c.

References ast_alloca, ast_log, ast_skip_blanks(), ast_strdup, ast_trim_blanks(), curl_cb_data::cache_control, curl_cb_data::expires, LOG_WARNING, MAX_HEADER_LENGTH, and value.

Referenced by get_curl_instance().

{
   struct curl_cb_data *cb_data = data;
   size_t realsize;
   char *header;
   char *value;

   realsize = size * nitems;

   if (realsize > MAX_HEADER_LENGTH) {
      ast_log(LOG_WARNING, "CURL header length is too large (size: '%zu' | max: '%d')\n",
         realsize, MAX_HEADER_LENGTH);
      return 0;
   }

   header = ast_alloca(realsize + 1);
   memcpy(header, buffer, realsize);
   header[realsize] = '\0';
   value = strchr(header, ':');
   if (!value) {
      return realsize;
   }
   *value++ = '\0';
   value = ast_trim_blanks(ast_skip_blanks(value));

   if (!strcasecmp(header, "Cache-Control")) {
      cb_data->cache_control = ast_strdup(value);
   } else if (!strcasecmp(header, "Expires")) {
      cb_data->expires = ast_strdup(value);
   }

   return realsize;
}

curl_public_key()

char* curl_public_key	(	const char *	public_cert_url,
		const char *	path,
		struct curl_cb_data *	data
	)

CURL the public key from the provided URL to the specified path.

Note

The returned string will need to be freed by the caller

Parameters

public_cert_url	The public cert URL
path	The path to download the file to
data	The curl_cb_data

Return values

NULL	on failure
full	path filename on success

Definition at line 185 of file curl.c.

References ast_asprintf, ast_free, ast_log, create_temp_file(), errno, get_curl_instance(), LOG_ERROR, NULL, RAII_VAR, and stir_shaken_get_serial_number_x509().

Referenced by run_curl().

{
   FILE *public_key_file;
   RAII_VAR(char *, tmp_filename, NULL, ast_free);
   char *filename;
   char *serial;
   int fd;
   long http_code;
   CURL *curl;
   char curl_errbuf[CURL_ERROR_SIZE + 1];

   curl_errbuf[CURL_ERROR_SIZE] = '\0';

   /* For now, it's fine to pass in path as is - it shouldn't end with a '/'. However,
    * if we decide to change how certificates are stored in the future (configurable paths),
    * then we will need to check to see if path ends with '/', copy everything up to the '/',
    * and use this new variable for create_temp_file as well as for ast_asprintf below.
    */
   fd = create_temp_file(path, &tmp_filename);
   if (fd == -1) {
      ast_log(LOG_ERROR, "Failed to get temporary file descriptor for CURL\n");
      return NULL;
   }

   public_key_file = fdopen(fd, "wb");
   if (!public_key_file) {
      ast_log(LOG_ERROR, "Failed to open file '%s' to write public key from '%s': %s (%d)\n",
         tmp_filename, public_cert_url, strerror(errno), errno);
      close(fd);
      remove(tmp_filename);
      return NULL;
   }

   curl = get_curl_instance(data);
   if (!curl) {
      ast_log(LOG_ERROR, "Failed to set up CURL isntance for '%s'\n", public_cert_url);
      fclose(public_key_file);
      remove(tmp_filename);
      return NULL;
   }

   curl_easy_setopt(curl, CURLOPT_URL, public_cert_url);
   curl_easy_setopt(curl, CURLOPT_WRITEDATA, public_key_file);
   curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, curl_errbuf);

   if (curl_easy_perform(curl)) {
      ast_log(LOG_ERROR, "%s\n", curl_errbuf);
      curl_easy_cleanup(curl);
      fclose(public_key_file);
      remove(tmp_filename);
      return NULL;
   }

   curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &http_code);

   curl_easy_cleanup(curl);
   fclose(public_key_file);

   if (http_code / 100 != 2) {
      ast_log(LOG_ERROR, "Failed to retrieve URL '%s': code %ld\n", public_cert_url, http_code);
      remove(tmp_filename);
      return NULL;
   }

   serial = stir_shaken_get_serial_number_x509(tmp_filename);
   if (!serial) {
      ast_log(LOG_ERROR, "Failed to get serial from cert %s\n", tmp_filename);
      remove(tmp_filename);
      return NULL;
   }

   if (ast_asprintf(&filename, "%s/%s.pem", path, serial) < 0) {
      ast_log(LOG_ERROR, "Failed to allocate memory for new filename for temporary "
         "file %s after CURL\n", tmp_filename);
      ast_free(serial);
      remove(tmp_filename);
      return NULL;
   }

   ast_free(serial);

   if (rename(tmp_filename, filename)) {
      ast_log(LOG_ERROR, "Failed to rename temporary file %s to %s after CURL\n", tmp_filename, filename);
      ast_free(filename);
      remove(tmp_filename);
      return NULL;
   }

   return filename;
}

get_curl_instance()

static CURL* get_curl_instance ( struct curl_cb_data *  data )

static

Prepare a CURL instance to use.

Parameters

data	The CURL callback data

Return values

NULL	on failure
CURL	instance on success

Definition at line 128 of file curl.c.

References ao2_cleanup, ast_stir_shaken_curl_timeout(), curl_header_callback(), stir_shaken_general::curl_timeout, GLOBAL_USERAGENT, NULL, and stir_shaken_general_get().

Referenced by curl_public_key().

{
   CURL *curl;
   struct stir_shaken_general *cfg;
   unsigned int curl_timeout;

   cfg = stir_shaken_general_get();
   curl_timeout = ast_stir_shaken_curl_timeout(cfg);
   ao2_cleanup(cfg);

   curl = curl_easy_init();
   if (!curl) {
      return NULL;
   }

   curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
   curl_easy_setopt(curl, CURLOPT_TIMEOUT, curl_timeout);
   curl_easy_setopt(curl, CURLOPT_USERAGENT, GLOBAL_USERAGENT);
   curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1);
   curl_easy_setopt(curl, CURLOPT_HEADERFUNCTION, curl_header_callback);
   curl_easy_setopt(curl, CURLOPT_HEADERDATA, data);

   return curl;
}