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util.h

/*
 * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef EVENT2_UTIL_H_INCLUDED_
#define EVENT2_UTIL_H_INCLUDED_

/** @file event2/util.h

Common convenience functions for cross-platform portability and
  related socket manipulations.

*/
#include <event2/visibility.h>

#ifdef __cplusplus
extern "C" {
#endif

#include <event2/event-config.h>
#ifdef EVENT__HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef EVENT__HAVE_STDINT_H
#include <stdint.h>
#elif defined(EVENT__HAVE_INTTYPES_H)
#include <inttypes.h>
#endif
#ifdef EVENT__HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef EVENT__HAVE_STDDEF_H
#include <stddef.h>
#endif
#ifdef _MSC_VER
#include <BaseTsd.h>
#endif
#include <stdarg.h>
#ifdef EVENT__HAVE_NETDB_H
#if !defined(_GNU_SOURCE)
#define _GNU_SOURCE
#endif
#include <netdb.h>
#endif

#ifdef _WIN32
#include <winsock2.h>
#ifdef EVENT__HAVE_GETADDRINFO
/* for EAI_* definitions. */
#include <ws2tcpip.h>
#endif
#else
#ifdef EVENT__HAVE_ERRNO_H
#include <errno.h>
#endif
#include <sys/socket.h>
#endif

#include <time.h>

/* Some openbsd autoconf versions get the name of this macro wrong. */
#if defined(EVENT__SIZEOF_VOID__) && !defined(EVENT__SIZEOF_VOID_P)
#define EVENT__SIZEOF_VOID_P EVENT__SIZEOF_VOID__
#endif

/**
 * @name Standard integer types.
 *
 * Integer type definitions for types that are supposed to be defined in the
 * C99-specified stdint.h.  Shamefully, some platforms do not include
 * stdint.h, so we need to replace it.  (If you are on a platform like this,
 * your C headers are now over 10 years out of date.  You should bug them to
 * do something about this.)
 *
 * We define:
 *
 * <dl>
 *   <dt>ev_uint64_t, ev_uint32_t, ev_uint16_t, ev_uint8_t</dt>
 *      <dd>unsigned integer types of exactly 64, 32, 16, and 8 bits
 *          respectively.</dd>
 *    <dt>ev_int64_t, ev_int32_t, ev_int16_t, ev_int8_t</dt>
 *      <dd>signed integer types of exactly 64, 32, 16, and 8 bits
 *          respectively.</dd>
 *    <dt>ev_uintptr_t, ev_intptr_t</dt>
 *      <dd>unsigned/signed integers large enough
 *      to hold a pointer without loss of bits.</dd>
 *    <dt>ev_ssize_t</dt>
 *      <dd>A signed type of the same size as size_t</dd>
 *    <dt>ev_off_t</dt>
 *      <dd>A signed type typically used to represent offsets within a
 *      (potentially large) file</dd>
 *
 * @{
 */
#ifdef EVENT__HAVE_UINT64_T
#define ev_uint64_t uint64_t
#define ev_int64_t int64_t
#elif defined(_WIN32)
#define ev_uint64_t unsigned __int64
#define ev_int64_t signed __int64
#elif EVENT__SIZEOF_LONG_LONG == 8
#define ev_uint64_t unsigned long long
#define ev_int64_t long long
#elif EVENT__SIZEOF_LONG == 8
#define ev_uint64_t unsigned long
#define ev_int64_t long
#elif defined(EVENT_IN_DOXYGEN_)
#define ev_uint64_t ...
#define ev_int64_t ...
#else
#error "No way to define ev_uint64_t"
#endif

#ifdef EVENT__HAVE_UINT32_T
#define ev_uint32_t uint32_t
#define ev_int32_t int32_t
#elif defined(_WIN32)
#define ev_uint32_t unsigned int
#define ev_int32_t signed int
#elif EVENT__SIZEOF_LONG == 4
#define ev_uint32_t unsigned long
#define ev_int32_t signed long
#elif EVENT__SIZEOF_INT == 4
#define ev_uint32_t unsigned int
#define ev_int32_t signed int
#elif defined(EVENT_IN_DOXYGEN_)
#define ev_uint32_t ...
#define ev_int32_t ...
#else
#error "No way to define ev_uint32_t"
#endif

#ifdef EVENT__HAVE_UINT16_T
#define ev_uint16_t uint16_t
#define ev_int16_t  int16_t
#elif defined(_WIN32)
#define ev_uint16_t unsigned short
#define ev_int16_t  signed short
#elif EVENT__SIZEOF_INT == 2
#define ev_uint16_t unsigned int
#define ev_int16_t  signed int
#elif EVENT__SIZEOF_SHORT == 2
#define ev_uint16_t unsigned short
#define ev_int16_t  signed short
#elif defined(EVENT_IN_DOXYGEN_)
#define ev_uint16_t ...
#define ev_int16_t ...
#else
#error "No way to define ev_uint16_t"
#endif

#ifdef EVENT__HAVE_UINT8_T
#define ev_uint8_t uint8_t
#define ev_int8_t int8_t
#elif defined(EVENT_IN_DOXYGEN_)
#define ev_uint8_t ...
#define ev_int8_t ...
#else
#define ev_uint8_t unsigned char
#define ev_int8_t signed char
#endif

#ifdef EVENT__HAVE_UINTPTR_T
#define ev_uintptr_t uintptr_t
#define ev_intptr_t intptr_t
#elif EVENT__SIZEOF_VOID_P <= 4
#define ev_uintptr_t ev_uint32_t
#define ev_intptr_t ev_int32_t
#elif EVENT__SIZEOF_VOID_P <= 8
#define ev_uintptr_t ev_uint64_t
#define ev_intptr_t ev_int64_t
#elif defined(EVENT_IN_DOXYGEN_)
#define ev_uintptr_t ...
#define ev_intptr_t ...
#else
#error "No way to define ev_uintptr_t"
#endif

#ifdef EVENT__ssize_t
#define ev_ssize_t EVENT__ssize_t
#else
#define ev_ssize_t ssize_t
#endif

/* Note that we define ev_off_t based on the compile-time size of off_t that
 * we used to build Libevent, and not based on the current size of off_t.
 * (For example, we don't define ev_off_t to off_t.).  We do this because
 * some systems let you build your software with different off_t sizes
 * at runtime, and so putting in any dependency on off_t would risk API
 * mismatch.
 */
#ifdef _WIN32
#define ev_off_t ev_int64_t
#elif EVENT__SIZEOF_OFF_T == 8
#define ev_off_t ev_int64_t
#elif EVENT__SIZEOF_OFF_T == 4
#define ev_off_t ev_int32_t
#elif defined(EVENT_IN_DOXYGEN_)
#define ev_off_t ...
#else
#define ev_off_t off_t
#endif
/**@}*/

/* Limits for integer types.

We're making two assumptions here:
     - The compiler does constant folding properly.
     - The platform does signed arithmetic in two's complement.
*/

/**
   @name Limits for integer types

These macros hold the largest or smallest values possible for the
   ev_[u]int*_t types.

@{
*/
#ifndef EVENT__HAVE_STDINT_H
#define EV_UINT64_MAX ((((ev_uint64_t)0xffffffffUL) << 32) | 0xffffffffUL)
#define EV_INT64_MAX  ((((ev_int64_t) 0x7fffffffL) << 32) | 0xffffffffL)
#define EV_INT64_MIN  ((-EV_INT64_MAX) - 1)
#define EV_UINT32_MAX ((ev_uint32_t)0xffffffffUL)
#define EV_INT32_MAX  ((ev_int32_t) 0x7fffffffL)
#define EV_INT32_MIN  ((-EV_INT32_MAX) - 1)
#define EV_UINT16_MAX ((ev_uint16_t)0xffffUL)
#define EV_INT16_MAX  ((ev_int16_t) 0x7fffL)
#define EV_INT16_MIN  ((-EV_INT16_MAX) - 1)
#define EV_UINT8_MAX  255
#define EV_INT8_MAX   127
#define EV_INT8_MIN   ((-EV_INT8_MAX) - 1)
#else
#define EV_UINT64_MAX UINT64_MAX
#define EV_INT64_MAX  INT64_MAX
#define EV_INT64_MIN  INT64_MIN
#define EV_UINT32_MAX UINT32_MAX
#define EV_INT32_MAX  INT32_MAX
#define EV_INT32_MIN  INT32_MIN
#define EV_UINT16_MAX UINT16_MAX
#define EV_INT16_MAX  INT16_MAX
#define EV_UINT8_MAX  UINT8_MAX
#define EV_INT8_MAX   INT8_MAX
#define EV_INT8_MIN   INT8_MIN
/** @} */
#endif

/**
   @name Limits for SIZE_T and SSIZE_T

@{
*/
#if EVENT__SIZEOF_SIZE_T == 8
#define EV_SIZE_MAX EV_UINT64_MAX
#define EV_SSIZE_MAX EV_INT64_MAX
#elif EVENT__SIZEOF_SIZE_T == 4
#define EV_SIZE_MAX EV_UINT32_MAX
#define EV_SSIZE_MAX EV_INT32_MAX
#elif defined(EVENT_IN_DOXYGEN_)
#define EV_SIZE_MAX ...
#define EV_SSIZE_MAX ...
#else
#error "No way to define SIZE_MAX"
#endif

#define EV_SSIZE_MIN ((-EV_SSIZE_MAX) - 1)
/**@}*/

#ifdef _WIN32
#define ev_socklen_t int
#elif defined(EVENT__socklen_t)
#define ev_socklen_t EVENT__socklen_t
#else
#define ev_socklen_t socklen_t
#endif

#ifdef EVENT__HAVE_STRUCT_SOCKADDR_STORAGE___SS_FAMILY
#if !defined(EVENT__HAVE_STRUCT_SOCKADDR_STORAGE_SS_FAMILY) \
 && !defined(ss_family)
#define ss_family __ss_family
#endif
#endif

/**
 * A type wide enough to hold the output of "socket()" or "accept()".  On
 * Windows, this is an intptr_t; elsewhere, it is an int. */
#ifdef _WIN32
#define evutil_socket_t intptr_t
#else
#define evutil_socket_t int
#endif

/**
 * Structure to hold information about a monotonic timer
 *
 * Use this with evutil_configure_monotonic_time() and
 * evutil_gettime_monotonic().
 *
 * This is an opaque structure; you can allocate one using
 * evutil_monotonic_timer_new().
 *
 * @see evutil_monotonic_timer_new(), evutil_monotonic_timer_free(),
 * evutil_configure_monotonic_time(), evutil_gettime_monotonic()
 */
struct evutil_monotonic_timer
#ifdef EVENT_IN_DOXYGEN_
{/*Empty body so that doxygen will generate documentation here.*/}
#endif
;

#define EV_MONOT_PRECISE  1
#define EV_MONOT_FALLBACK 2

/** Format a date string using RFC 1123 format (used in HTTP).
 * If `tm` is NULL, current system's time will be used.
 * The number of characters written will be returned.
 * One should check if the return value is smaller than `datelen` to check if
 * the result is truncated or not.
 */
EVENT2_EXPORT_SYMBOL int
evutil_date_rfc1123(char *date, const size_t datelen, const struct tm *tm);

/** Allocate a new struct evutil_monotonic_timer for use with the
 * evutil_configure_monotonic_time() and evutil_gettime_monotonic()
 * functions.  You must configure the timer with
 * evutil_configure_monotonic_time() before using it.
 */
EVENT2_EXPORT_SYMBOL
struct evutil_monotonic_timer * evutil_monotonic_timer_new(void);

/** Free a struct evutil_monotonic_timer that was allocated using
 * evutil_monotonic_timer_new().
 */
EVENT2_EXPORT_SYMBOL
void evutil_monotonic_timer_free(struct evutil_monotonic_timer *timer);

/** Set up a struct evutil_monotonic_timer; flags can include
 * EV_MONOT_PRECISE and EV_MONOT_FALLBACK.
 */
EVENT2_EXPORT_SYMBOL
int evutil_configure_monotonic_time(struct evutil_monotonic_timer *timer,
                                    int flags);

/** Query the current monotonic time from a struct evutil_monotonic_timer
 * previously configured with evutil_configure_monotonic_time().  Monotonic
 * time is guaranteed never to run in reverse, but is not necessarily epoch-
 * based, or relative to any other definite point.  Use it to make reliable
 * measurements of elapsed time between events even when the system time
 * may be changed.
 *
 * It is not safe to use this funtion on the same timer from multiple
 * threads.
 */
EVENT2_EXPORT_SYMBOL
int evutil_gettime_monotonic(struct evutil_monotonic_timer *timer,
                             struct timeval *tp);

/** Create two new sockets that are connected to each other.

On Unix, this simply calls socketpair().  On Windows, it uses the
    loopback network interface on 127.0.0.1, and only
    AF_INET,SOCK_STREAM are supported.

(This may fail on some Windows hosts where firewall software has cleverly
    decided to keep 127.0.0.1 from talking to itself.)

Parameters and return values are as for socketpair()
*/
EVENT2_EXPORT_SYMBOL
int evutil_socketpair(int d, int type, int protocol, evutil_socket_t sv[2]);
/** Do platform-specific operations as needed to make a socket nonblocking.

@param sock The socket to make nonblocking
    @return 0 on success, -1 on failure
 */
EVENT2_EXPORT_SYMBOL
int evutil_make_socket_nonblocking(evutil_socket_t sock);

/** Do platform-specific operations to make a listener socket reusable.

Specifically, we want to make sure that another program will be able
    to bind this address right after we've closed the listener.

This differs from Windows's interpretation of "reusable", which
    allows multiple listeners to bind the same address at the same time.

@param sock The socket to make reusable
    @return 0 on success, -1 on failure
 */
EVENT2_EXPORT_SYMBOL
int evutil_make_listen_socket_reuseable(evutil_socket_t sock);

/** Do platform-specific operations to make a listener port reusable.

Specifically, we want to make sure that multiple programs which also
    set the same socket option will be able to bind, listen at the same time.

This is a feature available only to Linux 3.9+

@param sock The socket to make reusable
    @return 0 on success, -1 on failure
 */
EVENT2_EXPORT_SYMBOL
int evutil_make_listen_socket_reuseable_port(evutil_socket_t sock);

/** Do platform-specific operations as needed to close a socket upon a
    successful execution of one of the exec*() functions.

@param sock The socket to be closed
    @return 0 on success, -1 on failure
 */
EVENT2_EXPORT_SYMBOL
int evutil_make_socket_closeonexec(evutil_socket_t sock);

/** Do the platform-specific call needed to close a socket returned from
    socket() or accept().

@param sock The socket to be closed
    @return 0 on success, -1 on failure
 */
EVENT2_EXPORT_SYMBOL
int evutil_closesocket(evutil_socket_t sock);
#define EVUTIL_CLOSESOCKET(s) evutil_closesocket(s)

/** Do platform-specific operations, if possible, to make a tcp listener
 *  socket defer accept()s until there is data to read.
 *  
 *  Not all platforms support this.  You don't want to do this for every
 *  listener socket: only the ones that implement a protocol where the
 *  client transmits before the server needs to respond.
 *
 *  @param sock The listening socket to to make deferred
 *  @return 0 on success (whether the operation is supported or not),
 *       -1 on failure
*/ 
EVENT2_EXPORT_SYMBOL
int evutil_make_tcp_listen_socket_deferred(evutil_socket_t sock);

#ifdef _WIN32
/** Return the most recent socket error.  Not idempotent on all platforms. */
#define EVUTIL_SOCKET_ERROR() WSAGetLastError()
/** Replace the most recent socket error with errcode */
#define EVUTIL_SET_SOCKET_ERROR(errcode)		\
	do { WSASetLastError(errcode); } while (0)
/** Return the most recent socket error to occur on sock. */
EVENT2_EXPORT_SYMBOL
int evutil_socket_geterror(evutil_socket_t sock);
/** Convert a socket error to a string. */
EVENT2_EXPORT_SYMBOL
const char *evutil_socket_error_to_string(int errcode);
#elif defined(EVENT_IN_DOXYGEN_)
/**
   @name Socket error functions

These functions are needed for making programs compatible between
   Windows and Unix-like platforms.

You see, Winsock handles socket errors differently from the rest of
   the world.  Elsewhere, a socket error is like any other error and is
   stored in errno.  But winsock functions require you to retrieve the
   error with a special function, and don't let you use strerror for
   the error codes.  And handling EWOULDBLOCK is ... different.

@{
*/
/** Return the most recent socket error.  Not idempotent on all platforms. */
#define EVUTIL_SOCKET_ERROR() ...
/** Replace the most recent socket error with errcode */
#define EVUTIL_SET_SOCKET_ERROR(errcode) ...
/** Return the most recent socket error to occur on sock. */
#define evutil_socket_geterror(sock) ...
/** Convert a socket error to a string. */
#define evutil_socket_error_to_string(errcode) ...
/**@}*/
#else
#define EVUTIL_SOCKET_ERROR() (errno)
#define EVUTIL_SET_SOCKET_ERROR(errcode)		\
		do { errno = (errcode); } while (0)
#define evutil_socket_geterror(sock) (errno)
#define evutil_socket_error_to_string(errcode) (strerror(errcode))
#endif

/**
 * @name Manipulation macros for struct timeval.
 *
 * We define replacements
 * for timeradd, timersub, timerclear, timercmp, and timerisset.
 *
 * @{
 */
#ifdef EVENT__HAVE_TIMERADD
#define evutil_timeradd(tvp, uvp, vvp) timeradd((tvp), (uvp), (vvp))
#define evutil_timersub(tvp, uvp, vvp) timersub((tvp), (uvp), (vvp))
#else
#define evutil_timeradd(tvp, uvp, vvp)					\
	do {								\
		(vvp)->tv_sec = (tvp)->tv_sec + (uvp)->tv_sec;		\
		(vvp)->tv_usec = (tvp)->tv_usec + (uvp)->tv_usec;       \
		if ((vvp)->tv_usec >= 1000000) {			\
			(vvp)->tv_sec++;				\
			(vvp)->tv_usec -= 1000000;			\
		}							\
	} while (0)
#define	evutil_timersub(tvp, uvp, vvp)					\
	do {								\
		(vvp)->tv_sec = (tvp)->tv_sec - (uvp)->tv_sec;		\
		(vvp)->tv_usec = (tvp)->tv_usec - (uvp)->tv_usec;	\
		if ((vvp)->tv_usec < 0) {				\
			(vvp)->tv_sec--;				\
			(vvp)->tv_usec += 1000000;			\
		}							\
	} while (0)
#endif /* !EVENT__HAVE_TIMERADD */

#ifdef EVENT__HAVE_TIMERCLEAR
#define evutil_timerclear(tvp) timerclear(tvp)
#else
#define	evutil_timerclear(tvp)	(tvp)->tv_sec = (tvp)->tv_usec = 0
#endif
/**@}*/

/** Return true iff the tvp is related to uvp according to the relational
 * operator cmp.  Recognized values for cmp are ==, <=, <, >=, and >. */
#define	evutil_timercmp(tvp, uvp, cmp)					\
	(((tvp)->tv_sec == (uvp)->tv_sec) ?				\
	 ((tvp)->tv_usec cmp (uvp)->tv_usec) :				\
	 ((tvp)->tv_sec cmp (uvp)->tv_sec))

#ifdef EVENT__HAVE_TIMERISSET
#define evutil_timerisset(tvp) timerisset(tvp)
#else
#define	evutil_timerisset(tvp)	((tvp)->tv_sec || (tvp)->tv_usec)
#endif

/** Replacement for offsetof on platforms that don't define it. */
#ifdef offsetof
#define evutil_offsetof(type, field) offsetof(type, field)
#else
#define evutil_offsetof(type, field) ((off_t)(&((type *)0)->field))
#endif

/* big-int related functions */
/** Parse a 64-bit value from a string.  Arguments are as for strtol. */
EVENT2_EXPORT_SYMBOL
ev_int64_t evutil_strtoll(const char *s, char **endptr, int base);

/** Replacement for gettimeofday on platforms that lack it. */
#ifdef EVENT__HAVE_GETTIMEOFDAY
#define evutil_gettimeofday(tv, tz) gettimeofday((tv), (tz))
#else
struct timezone;
EVENT2_EXPORT_SYMBOL
int evutil_gettimeofday(struct timeval *tv, struct timezone *tz);
#endif

/** Replacement for snprintf to get consistent behavior on platforms for
    which the return value of snprintf does not conform to C99.
 */
EVENT2_EXPORT_SYMBOL
int evutil_snprintf(char *buf, size_t buflen, const char *format, ...)
#ifdef __GNUC__
	__attribute__((format(printf, 3, 4)))
#endif
;
/** Replacement for vsnprintf to get consistent behavior on platforms for
    which the return value of snprintf does not conform to C99.
 */
EVENT2_EXPORT_SYMBOL
int evutil_vsnprintf(char *buf, size_t buflen, const char *format, va_list ap)
#ifdef __GNUC__
	__attribute__((format(printf, 3, 0)))
#endif
;

/** Replacement for inet_ntop for platforms which lack it. */
EVENT2_EXPORT_SYMBOL
const char *evutil_inet_ntop(int af, const void *src, char *dst, size_t len);
/** Replacement for inet_pton for platforms which lack it. */
EVENT2_EXPORT_SYMBOL
int evutil_inet_pton(int af, const char *src, void *dst);
struct sockaddr;

/** Parse an IPv4 or IPv6 address, with optional port, from a string.

Recognized formats are:
    - [IPv6Address]:port
    - [IPv6Address]
    - IPv6Address
    - IPv4Address:port
    - IPv4Address

If no port is specified, the port in the output is set to 0.

@param str The string to parse.
    @param out A struct sockaddr to hold the result.  This should probably be
       a struct sockaddr_storage.
    @param outlen A pointer to the number of bytes that that 'out' can safely
       hold.  Set to the number of bytes used in 'out' on success.
    @return -1 if the address is not well-formed, if the port is out of range,
       or if out is not large enough to hold the result.  Otherwise returns
       0 on success.
*/
EVENT2_EXPORT_SYMBOL
int evutil_parse_sockaddr_port(const char *str, struct sockaddr *out, int *outlen);

/** Compare two sockaddrs; return 0 if they are equal, or less than 0 if sa1
 * preceeds sa2, or greater than 0 if sa1 follows sa2.  If include_port is
 * true, consider the port as well as the address.  Only implemented for
 * AF_INET and AF_INET6 addresses. The ordering is not guaranteed to remain
 * the same between Libevent versions. */
EVENT2_EXPORT_SYMBOL
int evutil_sockaddr_cmp(const struct sockaddr *sa1, const struct sockaddr *sa2,
    int include_port);

/** As strcasecmp, but always compares the characters in locale-independent
    ASCII.  That's useful if you're handling data in ASCII-based protocols.
 */
EVENT2_EXPORT_SYMBOL
int evutil_ascii_strcasecmp(const char *str1, const char *str2);
/** As strncasecmp, but always compares the characters in locale-independent
    ASCII.  That's useful if you're handling data in ASCII-based protocols.
 */
EVENT2_EXPORT_SYMBOL
int evutil_ascii_strncasecmp(const char *str1, const char *str2, size_t n);

/* Here we define evutil_addrinfo to the native addrinfo type, or redefine it
 * if this system has no getaddrinfo(). */
#ifdef EVENT__HAVE_STRUCT_ADDRINFO
#define evutil_addrinfo addrinfo
#else
/** A definition of struct addrinfo for systems that lack it.

(This is just an alias for struct addrinfo if the system defines
    struct addrinfo.)
*/
struct evutil_addrinfo {
	int     ai_flags;     /* AI_PASSIVE, AI_CANONNAME, AI_NUMERICHOST */
	int     ai_family;    /* PF_xxx */
	int     ai_socktype;  /* SOCK_xxx */
	int     ai_protocol;  /* 0 or IPPROTO_xxx for IPv4 and IPv6 */
	size_t  ai_addrlen;   /* length of ai_addr */
	char   *ai_canonname; /* canonical name for nodename */
	struct sockaddr  *ai_addr; /* binary address */
	struct evutil_addrinfo  *ai_next; /* next structure in linked list */
};
#endif
/** @name evutil_getaddrinfo() error codes

These values are possible error codes for evutil_getaddrinfo() and
    related functions.

@{
*/
#if defined(EAI_ADDRFAMILY) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_ADDRFAMILY EAI_ADDRFAMILY
#else
#define EVUTIL_EAI_ADDRFAMILY -901
#endif
#if defined(EAI_AGAIN) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_AGAIN EAI_AGAIN
#else
#define EVUTIL_EAI_AGAIN -902
#endif
#if defined(EAI_BADFLAGS) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_BADFLAGS EAI_BADFLAGS
#else
#define EVUTIL_EAI_BADFLAGS -903
#endif
#if defined(EAI_FAIL) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_FAIL EAI_FAIL
#else
#define EVUTIL_EAI_FAIL -904
#endif
#if defined(EAI_FAMILY) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_FAMILY EAI_FAMILY
#else
#define EVUTIL_EAI_FAMILY -905
#endif
#if defined(EAI_MEMORY) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_MEMORY EAI_MEMORY
#else
#define EVUTIL_EAI_MEMORY -906
#endif
/* This test is a bit complicated, since some MS SDKs decide to
 * remove NODATA or redefine it to be the same as NONAME, in a
 * fun interpretation of RFC 2553 and RFC 3493. */
#if defined(EAI_NODATA) && defined(EVENT__HAVE_GETADDRINFO) && (!defined(EAI_NONAME) || EAI_NODATA != EAI_NONAME)
#define EVUTIL_EAI_NODATA EAI_NODATA
#else
#define EVUTIL_EAI_NODATA -907
#endif
#if defined(EAI_NONAME) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_NONAME EAI_NONAME
#else
#define EVUTIL_EAI_NONAME -908
#endif
#if defined(EAI_SERVICE) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_SERVICE EAI_SERVICE
#else
#define EVUTIL_EAI_SERVICE -909
#endif
#if defined(EAI_SOCKTYPE) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_SOCKTYPE EAI_SOCKTYPE
#else
#define EVUTIL_EAI_SOCKTYPE -910
#endif
#if defined(EAI_SYSTEM) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_EAI_SYSTEM EAI_SYSTEM
#else
#define EVUTIL_EAI_SYSTEM -911
#endif

#define EVUTIL_EAI_CANCEL -90001

#if defined(AI_PASSIVE) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_AI_PASSIVE AI_PASSIVE
#else
#define EVUTIL_AI_PASSIVE 0x1000
#endif
#if defined(AI_CANONNAME) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_AI_CANONNAME AI_CANONNAME
#else
#define EVUTIL_AI_CANONNAME 0x2000
#endif
#if defined(AI_NUMERICHOST) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_AI_NUMERICHOST AI_NUMERICHOST
#else
#define EVUTIL_AI_NUMERICHOST 0x4000
#endif
#if defined(AI_NUMERICSERV) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_AI_NUMERICSERV AI_NUMERICSERV
#else
#define EVUTIL_AI_NUMERICSERV 0x8000
#endif
#if defined(AI_V4MAPPED) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_AI_V4MAPPED AI_V4MAPPED
#else
#define EVUTIL_AI_V4MAPPED 0x10000
#endif
#if defined(AI_ALL) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_AI_ALL AI_ALL
#else
#define EVUTIL_AI_ALL 0x20000
#endif
#if defined(AI_ADDRCONFIG) && defined(EVENT__HAVE_GETADDRINFO)
#define EVUTIL_AI_ADDRCONFIG AI_ADDRCONFIG
#else
#define EVUTIL_AI_ADDRCONFIG 0x40000
#endif
/**@}*/

struct evutil_addrinfo;
/**
 * This function clones getaddrinfo for systems that don't have it.  For full
 * details, see RFC 3493, section 6.1.
 *
 * Limitations:
 * - When the system has no getaddrinfo, we fall back to gethostbyname_r or
 *   gethostbyname, with their attendant issues.
 * - The AI_V4MAPPED and AI_ALL flags are not currently implemented.
 *
 * For a nonblocking variant, see evdns_getaddrinfo.
 */
EVENT2_EXPORT_SYMBOL
int evutil_getaddrinfo(const char *nodename, const char *servname,
    const struct evutil_addrinfo *hints_in, struct evutil_addrinfo **res);

/** Release storage allocated by evutil_getaddrinfo or evdns_getaddrinfo. */
EVENT2_EXPORT_SYMBOL
void evutil_freeaddrinfo(struct evutil_addrinfo *ai);

EVENT2_EXPORT_SYMBOL
const char *evutil_gai_strerror(int err);

/** Generate n bytes of secure pseudorandom data, and store them in buf.
 *
 * Current versions of Libevent use an ARC4-based random number generator,
 * seeded using the platform's entropy source (/dev/urandom on Unix-like
 * systems; CryptGenRandom on Windows).  This is not actually as secure as it
 * should be: ARC4 is a pretty lousy cipher, and the current implementation
 * provides only rudimentary prediction- and backtracking-resistance.  Don't
 * use this for serious cryptographic applications.
 */
EVENT2_EXPORT_SYMBOL
void evutil_secure_rng_get_bytes(void *buf, size_t n);

/**
 * Seed the secure random number generator if needed, and return 0 on
 * success or -1 on failure.
 *
 * It is okay to call this function more than once; it will still return
 * 0 if the RNG has been successfully seeded and -1 if it can't be
 * seeded.
 *
 * Ordinarily you don't need to call this function from your own code;
 * Libevent will seed the RNG itself the first time it needs good random
 * numbers.  You only need to call it if (a) you want to double-check
 * that one of the seeding methods did succeed, or (b) you plan to drop
 * the capability to seed (by chrooting, or dropping capabilities, or
 * whatever), and you want to make sure that seeding happens before your
 * program loses the ability to do it.
 */
EVENT2_EXPORT_SYMBOL
int evutil_secure_rng_init(void);

/**
 * Set a filename to use in place of /dev/urandom for seeding the secure
 * PRNG. Return 0 on success, -1 on failure.
 *
 * Call this function BEFORE calling any other initialization or RNG
 * functions.
 *
 * (This string will _NOT_ be copied internally. Do not free it while any
 * user of the secure RNG might be running. Don't pass anything other than a
 * real /dev/...random device file here, or you might lose security.)
 *
 * This API is unstable, and might change in a future libevent version.
 */
EVENT2_EXPORT_SYMBOL
int evutil_secure_rng_set_urandom_device_file(char *fname);

/** Seed the random number generator with extra random bytes.

You should almost never need to call this function; it should be
    sufficient to invoke evutil_secure_rng_init(), or let Libevent take
    care of calling evutil_secure_rng_init() on its own.

If you call this function as a _replacement_ for the regular
    entropy sources, then you need to be sure that your input
    contains a fairly large amount of strong entropy.  Doing so is
    notoriously hard: most people who try get it wrong.  Watch out!

@param dat a buffer full of a strong source of random numbers
    @param datlen the number of bytes to read from datlen
 */
EVENT2_EXPORT_SYMBOL
void evutil_secure_rng_add_bytes(const char *dat, size_t datlen);

#ifdef __cplusplus
}
#endif

#endif /* EVENT1_EVUTIL_H_INCLUDED_ */

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