Sat Nov 1 06:26:11 2008

Asterisk developer's documentation

---

utils.h

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2006, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 * \brief Utility functions
 */

#ifndef _ASTERISK_UTILS_H
#define _ASTERISK_UTILS_H

#include "asterisk/network.h"

#include <time.h> /* we want to override localtime_r */
#include <unistd.h>

#include "asterisk/lock.h"
#include "asterisk/time.h"
#include "asterisk/logger.h"
#include "asterisk/localtime.h"

/*! 
\note \verbatim
   Note:
   It is very important to use only unsigned variables to hold
   bit flags, as otherwise you can fall prey to the compiler's
   sign-extension antics if you try to use the top two bits in
   your variable.

   The flag macros below use a set of compiler tricks to verify
   that the caller is using an "unsigned int" variable to hold
   the flags, and nothing else. If the caller uses any other
   type of variable, a warning message similar to this:

   warning: comparison of distinct pointer types lacks cast
   will be generated.

   The "dummy" variable below is used to make these comparisons.

   Also note that at -O2 or above, this type-safety checking
   does _not_ produce any additional object code at all.
 \endverbatim
*/

extern unsigned int __unsigned_int_flags_dummy;

#define ast_test_flag(p,flag)       ({ \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy) __x = 0; \
               (void) (&__p == &__x); \
               ((p)->flags & (flag)); \
               })

#define ast_set_flag(p,flag)     do { \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy) __x = 0; \
               (void) (&__p == &__x); \
               ((p)->flags |= (flag)); \
               } while(0)

#define ast_clear_flag(p,flag)      do { \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy) __x = 0; \
               (void) (&__p == &__x); \
               ((p)->flags &= ~(flag)); \
               } while(0)

#define ast_copy_flags(dest,src,flagz) do { \
               typeof ((dest)->flags) __d = (dest)->flags; \
               typeof ((src)->flags) __s = (src)->flags; \
               typeof (__unsigned_int_flags_dummy) __x = 0; \
               (void) (&__d == &__x); \
               (void) (&__s == &__x); \
               (dest)->flags &= ~(flagz); \
               (dest)->flags |= ((src)->flags & (flagz)); \
               } while (0)

#define ast_set2_flag(p,value,flag) do { \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy) __x = 0; \
               (void) (&__p == &__x); \
               if (value) \
                  (p)->flags |= (flag); \
               else \
                  (p)->flags &= ~(flag); \
               } while (0)

#define ast_set_flags_to(p,flag,value) do { \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy) __x = 0; \
               (void) (&__p == &__x); \
               (p)->flags &= ~(flag); \
               (p)->flags |= (value); \
               } while (0)


/* The following 64-bit flag code can most likely be erased after app_dial
   is reorganized to either reduce the large number of options, or handle
   them in some other way. At the time of this writing, app_dial would be
   the only user of 64-bit option flags */

extern uint64_t __unsigned_int_flags_dummy64;

#define ast_test_flag64(p,flag)     ({ \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy64) __x = 0; \
               (void) (&__p == &__x); \
               ((p)->flags & (flag)); \
               })

#define ast_set_flag64(p,flag)      do { \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy64) __x = 0; \
               (void) (&__p == &__x); \
               ((p)->flags |= (flag)); \
               } while(0)

#define ast_clear_flag64(p,flag)       do { \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy64) __x = 0; \
               (void) (&__p == &__x); \
               ((p)->flags &= ~(flag)); \
               } while(0)

#define ast_copy_flags64(dest,src,flagz)  do { \
               typeof ((dest)->flags) __d = (dest)->flags; \
               typeof ((src)->flags) __s = (src)->flags; \
               typeof (__unsigned_int_flags_dummy64) __x = 0; \
               (void) (&__d == &__x); \
               (void) (&__s == &__x); \
               (dest)->flags &= ~(flagz); \
               (dest)->flags |= ((src)->flags & (flagz)); \
               } while (0)

#define ast_set2_flag64(p,value,flag)  do { \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy64) __x = 0; \
               (void) (&__p == &__x); \
               if (value) \
                  (p)->flags |= (flag); \
               else \
                  (p)->flags &= ~(flag); \
               } while (0)

#define ast_set_flags_to64(p,flag,value)  do { \
               typeof ((p)->flags) __p = (p)->flags; \
               typeof (__unsigned_int_flags_dummy64) __x = 0; \
               (void) (&__p == &__x); \
               (p)->flags &= ~(flag); \
               (p)->flags |= (value); \
               } while (0)


/* Non-type checking variations for non-unsigned int flags.  You
   should only use non-unsigned int flags where required by 
   protocol etc and if you know what you're doing :)  */
#define ast_test_flag_nonstd(p,flag) \
               ((p)->flags & (flag))

#define ast_set_flag_nonstd(p,flag)       do { \
               ((p)->flags |= (flag)); \
               } while(0)

#define ast_clear_flag_nonstd(p,flag)     do { \
               ((p)->flags &= ~(flag)); \
               } while(0)

#define ast_copy_flags_nonstd(dest,src,flagz)   do { \
               (dest)->flags &= ~(flagz); \
               (dest)->flags |= ((src)->flags & (flagz)); \
               } while (0)

#define ast_set2_flag_nonstd(p,value,flag)   do { \
               if (value) \
                  (p)->flags |= (flag); \
               else \
                  (p)->flags &= ~(flag); \
               } while (0)

#define AST_FLAGS_ALL UINT_MAX

/*! \brief Structure used to handle boolean flags 
*/
struct ast_flags {
   unsigned int flags;
};

/*! \brief Structure used to handle a large number of boolean flags == used only in app_dial?
*/
struct ast_flags64 {
   uint64_t flags;
};

struct ast_hostent {
   struct hostent hp;
   char buf[1024];
};

/*! \brief Thread-safe gethostbyname function to use in Asterisk */
struct hostent *ast_gethostbyname(const char *host, struct ast_hostent *hp);

/*!  \brief Produces MD5 hash based on input string */
void ast_md5_hash(char *output, char *input);
/*! \brief Produces SHA1 hash based on input string */
void ast_sha1_hash(char *output, char *input);

int ast_base64encode_full(char *dst, const unsigned char *src, int srclen, int max, int linebreaks);

/*!
 * \brief Encode data in base64
 * \param dst the destination buffer
 * \param src the source data to be encoded
 * \param srclen the number of bytes present in the source buffer
 * \param max the maximum number of bytes to write into the destination
 *        buffer, *including* the terminating NULL character.
 */
int ast_base64encode(char *dst, const unsigned char *src, int srclen, int max);

/*!
 * \brief Decode data from base64
 * \param dst the destination buffer
 * \param src the source buffer
 * \param max The maximum number of bytes to write into the destination
 *            buffer.  Note that this function will not ensure that the
 *            destination buffer is NULL terminated.  So, in general,
 *            this parameter should be sizeof(dst) - 1.
 */
int ast_base64decode(unsigned char *dst, const char *src, int max);

/*!  \brief Turn text string to URI-encoded %XX version 

\note    At this point, we're converting from ISO-8859-x (8-bit), not UTF8
   as in the SIP protocol spec 
   If doreserved == 1 we will convert reserved characters also.
   RFC 2396, section 2.4
   outbuf needs to have more memory allocated than the instring
   to have room for the expansion. Every char that is converted
   is replaced by three ASCII characters.
   \param string  String to be converted
   \param outbuf  Resulting encoded string
   \param buflen  Size of output buffer
   \param doreserved Convert reserved characters
*/

char *ast_uri_encode(const char *string, char *outbuf, int buflen, int doreserved);

/*!   \brief Decode URI, URN, URL (overwrite string)
   \param s String to be decoded 
 */
void ast_uri_decode(char *s);

static force_inline void ast_slinear_saturated_add(short *input, short *value)
{
   int res;

   res = (int) *input + *value;
   if (res > 32767)
      *input = 32767;
   else if (res < -32767)
      *input = -32767;
   else
      *input = (short) res;
}

static force_inline void ast_slinear_saturated_subtract(short *input, short *value)
{
   int res;

   res = (int) *input - *value;
   if (res > 32767)
      *input = 32767;
   else if (res < -32767)
      *input = -32767;
   else
      *input = (short) res;
}
   
static force_inline void ast_slinear_saturated_multiply(short *input, short *value)
{
   int res;

   res = (int) *input * *value;
   if (res > 32767)
      *input = 32767;
   else if (res < -32767)
      *input = -32767;
   else
      *input = (short) res;
}

static force_inline void ast_slinear_saturated_divide(short *input, short *value)
{
   *input /= *value;
}

int test_for_thread_safety(void);

#ifdef localtime_r
#undef localtime_r
#endif
#define localtime_r __dont_use_localtime_r_use_ast_localtime_instead__

int ast_utils_init(void);
int ast_wait_for_input(int fd, int ms);

/*!
   \brief Try to write string, but wait no more than ms milliseconds
   before timing out.

   \note If you are calling ast_carefulwrite, it is assumed that you are calling
   it on a file descriptor that _DOES_ have NONBLOCK set.  This way,
   there is only one system call made to do a write, unless we actually
   have a need to wait.  This way, we get better performance.
*/
int ast_carefulwrite(int fd, char *s, int len, int timeoutms);

/*
 * Thread management support (should be moved to lock.h or a different header)
 */
 
#define AST_STACKSIZE 240 * 1024

#if defined(LOW_MEMORY)
#define AST_BACKGROUND_STACKSIZE 48 * 1024
#else
#define AST_BACKGROUND_STACKSIZE 240 * 1024
#endif

void ast_register_thread(char *name);
void ast_unregister_thread(void *id);

int ast_pthread_create_stack(pthread_t *thread, pthread_attr_t *attr, void *(*start_routine)(void *),
              void *data, size_t stacksize, const char *file, const char *caller,
              int line, const char *start_fn);

int ast_pthread_create_detached_stack(pthread_t *thread, pthread_attr_t *attr, void*(*start_routine)(void *),
             void *data, size_t stacksize, const char *file, const char *caller,
             int line, const char *start_fn);

#define ast_pthread_create(a, b, c, d)             \
   ast_pthread_create_stack(a, b, c, d,         \
      0, __FILE__, __FUNCTION__, __LINE__, #c)

#define ast_pthread_create_detached(a, b, c, d)       \
   ast_pthread_create_detached_stack(a, b, c, d,      \
      0, __FILE__, __FUNCTION__, __LINE__, #c)

#define ast_pthread_create_background(a, b, c, d)     \
   ast_pthread_create_stack(a, b, c, d,         \
      AST_BACKGROUND_STACKSIZE,        \
      __FILE__, __FUNCTION__, __LINE__, #c)

#define ast_pthread_create_detached_background(a, b, c, d)  \
   ast_pthread_create_detached_stack(a, b, c, d,      \
      AST_BACKGROUND_STACKSIZE,        \
      __FILE__, __FUNCTION__, __LINE__, #c)

/* End of thread management support */

/*!
   \brief Process a string to find and replace characters
   \param start The string to analyze
   \param find The character to find
   \param replace_with The character that will replace the one we are looking for
*/
char *ast_process_quotes_and_slashes(char *start, char find, char replace_with);

long int ast_random(void);

#define ast_free free

/*! 
 * \brief free() wrapper
 *
 * ast_free_ptr should be used when a function pointer for free() needs to be passed
 * as the argument to a function. Otherwise, astmm will cause seg faults.
 */
#ifdef __AST_DEBUG_MALLOC
static void ast_free_ptr(void *ptr) attribute_unused;
static void ast_free_ptr(void *ptr)
{
   ast_free(ptr);
}
#else
#define ast_free_ptr ast_free
#endif

#ifndef __AST_DEBUG_MALLOC

#define MALLOC_FAILURE_MSG \
   ast_log(LOG_ERROR, "Memory Allocation Failure in function %s at line %d of %s\n", func, lineno, file);
/*!
 * \brief A wrapper for malloc()
 *
 * ast_malloc() is a wrapper for malloc() that will generate an Asterisk log
 * message in the case that the allocation fails.
 *
 * The argument and return value are the same as malloc()
 */
#define ast_malloc(len) \
   _ast_malloc((len), __FILE__, __LINE__, __PRETTY_FUNCTION__)

AST_INLINE_API(
void * attribute_malloc _ast_malloc(size_t len, const char *file, int lineno, const char *func),
{
   void *p;

   if (!(p = malloc(len)))
      MALLOC_FAILURE_MSG;

   return p;
}
)

/*!
 * \brief A wrapper for calloc()
 *
 * ast_calloc() is a wrapper for calloc() that will generate an Asterisk log
 * message in the case that the allocation fails.
 *
 * The arguments and return value are the same as calloc()
 */
#define ast_calloc(num, len) \
   _ast_calloc((num), (len), __FILE__, __LINE__, __PRETTY_FUNCTION__)

AST_INLINE_API(
void * attribute_malloc _ast_calloc(size_t num, size_t len, const char *file, int lineno, const char *func),
{
   void *p;

   if (!(p = calloc(num, len)))
      MALLOC_FAILURE_MSG;

   return p;
}
)

/*!
 * \brief A wrapper for calloc() for use in cache pools
 *
 * ast_calloc_cache() is a wrapper for calloc() that will generate an Asterisk log
 * message in the case that the allocation fails. When memory debugging is in use,
 * the memory allocated by this function will be marked as 'cache' so it can be
 * distinguished from normal memory allocations.
 *
 * The arguments and return value are the same as calloc()
 */
#define ast_calloc_cache(num, len) \
   _ast_calloc((num), (len), __FILE__, __LINE__, __PRETTY_FUNCTION__)

/*!
 * \brief A wrapper for realloc()
 *
 * ast_realloc() is a wrapper for realloc() that will generate an Asterisk log
 * message in the case that the allocation fails.
 *
 * The arguments and return value are the same as realloc()
 */
#define ast_realloc(p, len) \
   _ast_realloc((p), (len), __FILE__, __LINE__, __PRETTY_FUNCTION__)

AST_INLINE_API(
void * attribute_malloc _ast_realloc(void *p, size_t len, const char *file, int lineno, const char *func),
{
   void *newp;

   if (!(newp = realloc(p, len)))
      MALLOC_FAILURE_MSG;

   return newp;
}
)

/*!
 * \brief A wrapper for strdup()
 *
 * ast_strdup() is a wrapper for strdup() that will generate an Asterisk log
 * message in the case that the allocation fails.
 *
 * ast_strdup(), unlike strdup(), can safely accept a NULL argument. If a NULL
 * argument is provided, ast_strdup will return NULL without generating any
 * kind of error log message.
 *
 * The argument and return value are the same as strdup()
 */
#define ast_strdup(str) \
   _ast_strdup((str), __FILE__, __LINE__, __PRETTY_FUNCTION__)

AST_INLINE_API(
char * attribute_malloc _ast_strdup(const char *str, const char *file, int lineno, const char *func),
{
   char *newstr = NULL;

   if (str) {
      if (!(newstr = strdup(str)))
         MALLOC_FAILURE_MSG;
   }

   return newstr;
}
)

/*!
 * \brief A wrapper for strndup()
 *
 * ast_strndup() is a wrapper for strndup() that will generate an Asterisk log
 * message in the case that the allocation fails.
 *
 * ast_strndup(), unlike strndup(), can safely accept a NULL argument for the
 * string to duplicate. If a NULL argument is provided, ast_strdup will return  
 * NULL without generating any kind of error log message.
 *
 * The arguments and return value are the same as strndup()
 */
#define ast_strndup(str, len) \
   _ast_strndup((str), (len), __FILE__, __LINE__, __PRETTY_FUNCTION__)

AST_INLINE_API(
char * attribute_malloc _ast_strndup(const char *str, size_t len, const char *file, int lineno, const char *func),
{
   char *newstr = NULL;

   if (str) {
      if (!(newstr = strndup(str, len)))
         MALLOC_FAILURE_MSG;
   }

   return newstr;
}
)

/*!
 * \brief A wrapper for asprintf()
 *
 * ast_asprintf() is a wrapper for asprintf() that will generate an Asterisk log
 * message in the case that the allocation fails.
 *
 * The arguments and return value are the same as asprintf()
 */
#define ast_asprintf(ret, fmt, ...) \
   _ast_asprintf((ret), __FILE__, __LINE__, __PRETTY_FUNCTION__, fmt, __VA_ARGS__)

int __attribute__((format (printf, 5, 6)))
   _ast_asprintf(char **ret, const char *file, int lineno, const char *func, const char *fmt, ...);

/*!
 * \brief A wrapper for vasprintf()
 *
 * ast_vasprintf() is a wrapper for vasprintf() that will generate an Asterisk log
 * message in the case that the allocation fails.
 *
 * The arguments and return value are the same as vasprintf()
 */
#define ast_vasprintf(ret, fmt, ap) \
   _ast_vasprintf((ret), __FILE__, __LINE__, __PRETTY_FUNCTION__, (fmt), (ap))

AST_INLINE_API(
__attribute__((format (printf, 5, 0)))
int _ast_vasprintf(char **ret, const char *file, int lineno, const char *func, const char *fmt, va_list ap),
{
   int res;

   if ((res = vasprintf(ret, fmt, ap)) == -1)
      MALLOC_FAILURE_MSG;

   return res;
}
)

#else

/* If astmm is in use, let it handle these.  Otherwise, it will report that
   all allocations are coming from this header file */

#define ast_malloc(a)      malloc(a)
#define ast_calloc(a,b)    calloc(a,b)
#define ast_realloc(a,b)   realloc(a,b)
#define ast_strdup(a)      strdup(a)
#define ast_strndup(a,b)   strndup(a,b)
#define ast_asprintf(a,b,...) asprintf(a,b,__VA_ARGS__)
#define ast_vasprintf(a,b,c)  vasprintf(a,b,c)

#endif /* AST_DEBUG_MALLOC */

#if !defined(ast_strdupa) && defined(__GNUC__)
/*!
  \brief duplicate a string in memory from the stack
  \param s The string to duplicate

  This macro will duplicate the given string.  It returns a pointer to the stack
  allocatted memory for the new string.
*/
#define ast_strdupa(s)                                                    \
   (__extension__                                                    \
   ({                                                                \
      const char *__old = (s);                                  \
      size_t __len = strlen(__old) + 1;                         \
      char *__new = __builtin_alloca(__len);                    \
      memcpy (__new, __old, __len);                             \
      __new;                                                    \
   }))
#endif

/*!
  \brief Disable PMTU discovery on a socket
  \param sock The socket to manipulate
  \return Nothing

  On Linux, UDP sockets default to sending packets with the Dont Fragment (DF)
  bit set. This is supposedly done to allow the application to do PMTU
  discovery, but Asterisk does not do this.

  Because of this, UDP packets sent by Asterisk that are larger than the MTU
  of any hop in the path will be lost. This function can be called on a socket
  to ensure that the DF bit will not be set.
 */
void ast_enable_packet_fragmentation(int sock);

/*!
  \brief Recursively create directory path
  \param path The directory path to create
  \param mode The permissions with which to try to create the directory
  \return 0 on success or an error code otherwise

  Creates a directory path, creating parent directories as needed.
 */
int ast_mkdir(const char *path, int mode);

#define ARRAY_LEN(a) (sizeof(a) / sizeof(a[0]))

#ifdef AST_DEVMODE
#define ast_assert(a) _ast_assert(a, # a, __FILE__, __LINE__, __PRETTY_FUNCTION__)
static void force_inline _ast_assert(int condition, const char *condition_str, 
   const char *file, int line, const char *function)
{
   if (__builtin_expect(!condition, 1)) {
      /* Attempt to put it into the logger, but hope that at least someone saw the
       * message on stderr ... */
      ast_log(__LOG_ERROR, file, line, function, "FRACK!, Failed assertion %s (%d)\n",
         condition_str, condition);
      fprintf(stderr, "FRACK!, Failed assertion %s (%d) at line %d in %s of %s\n",
         condition_str, condition, line, function, file);
      /* Give the logger a chance to get the message out, just in case we abort(), or
       * Asterisk crashes due to whatever problem just happened after we exit ast_assert(). */
      usleep(1);
#ifdef DO_CRASH
      abort();
      /* Just in case abort() doesn't work or something else super silly,
       * and for Qwell's amusement. */
      *((int*)0)=0;
#endif
   }
}
#else
#define ast_assert(a)
#endif

#include "asterisk/strings.h"

/*!
 * \brief An Entity ID is essentially a MAC address, brief and unique 
 */
struct ast_eid {
   unsigned char eid[6];
} __attribute__ ((__packed__));

/*!
 * \brief Global EID
 *
 * This is set in asterisk.conf, or determined automatically by taking the mac
 * address of an Ethernet interface on the system.
 */
extern struct ast_eid g_eid;

/*!
 * \brief Fill in an ast_eid with the default eid of this machine
 */
void ast_set_default_eid(struct ast_eid *eid);

/*!
 * /brief Convert an EID to a string
 */
char *ast_eid_to_str(char *s, int maxlen, struct ast_eid *eid);

/*!
 * \brief Convert a string into an EID
 *
 * This function expects an EID in the format:
 *    00:11:22:33:44:55
 *
 * \return 0 success, non-zero failure
 */
int ast_str_to_eid(struct ast_eid *eid, const char *s);

/*!
 * \brief Compare two EIDs
 *
 * \return 0 if the two are the same, non-zero otherwise
 */
int ast_eid_cmp(const struct ast_eid *eid1, const struct ast_eid *eid2);

#endif /* _ASTERISK_UTILS_H */

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