third_party/mongoose/mongoose.c

/*
 * Copyright (c) 2004-2009 Sergey Lyubka
 * Portions Copyright (c) 2009 Gilbert Wellisch
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * $Id: mongoose.c 446 2009-07-08 21:06:56Z valenok $
 */

#if defined(_WIN32)
#define _CRT_SECURE_NO_WARNINGS /* Disable deprecation warning in VS2005 */
#endif /* _WIN32 */

#ifndef _WIN32_WCE /* Some ANSI #includes are not available on Windows CE */
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#endif /* !_WIN32_WCE */

#include <time.h>
#include <stdlib.h>
#include <stdarg.h>
#include <assert.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include <stddef.h>
#include <stdio.h>

#if defined(_WIN32)   /* Windows specific #includes and #defines */
  #ifdef _WIN32_WINNT
    #undef _WIN32_WINNT
    #define _WIN32_WINNT  0x0400  /* To make it link in VS2005 */
  #else
    #define _WIN32_WINNT  0x0400  /* To make it link in VS2005 */
  #endif
#include <windows.h>
#include <winsock2.h>

#ifndef _WIN32_WCE
#include <process.h>
#include <direct.h>
#include <io.h>
#else /* _WIN32_WCE */
/* Windows CE-specific definitions */
#include <winsock2.h>
#define NO_CGI  /* WinCE has no pipes */
#define NO_SSI  /* WinCE has no pipes */

#define FILENAME_MAX  MAX_PATH
#define BUFSIZ    4096
typedef long off_t;

#define errno     GetLastError()
#define strerror(x)   _ultoa(x, (char *) _alloca(sizeof(x) *3 ), 10)
#endif /* _WIN32_WCE */

#define EPOCH_DIFF  0x019DB1DED53E8000 /* 116444736000000000 nsecs */
#define RATE_DIFF 10000000 /* 100 nsecs */
#define MAKEUQUAD(lo, hi) ((uint64_t)(((uint32_t)(lo)) | \
        ((uint64_t)((uint32_t)(hi))) << 32))
#define SYS2UNIX_TIME(lo, hi) \
  (time_t) ((MAKEUQUAD((lo), (hi)) - EPOCH_DIFF) / RATE_DIFF)

/*
 * Visual Studio 6 does not know __func__ or __FUNCTION__
 * The rest of MS compilers use __FUNCTION__, not C99 __func__
 */
#if defined(_MSC_VER) && _MSC_VER < 1300
#define STRX(x)     #x
#define STR(x)      STRX(x)
#define __func__    "line " STR(__LINE__)
#else
#define __func__    __FUNCTION__
#endif /* _MSC_VER */

#define ERRNO     GetLastError()
#define NO_SOCKLEN_T
#define SSL_LIB     "ssleay32.dll"
#define CRYPTO_LIB    "libeay32.dll"
#define DIRSEP      '\\'
#define IS_DIRSEP_CHAR(c) ((c) == '/' || (c) == '\\')
#define O_NONBLOCK    0
#if !defined(_MSC_VER) || _MSC_VER < 1600
#define EWOULDBLOCK   WSAEWOULDBLOCK
#endif
#define _POSIX_
#define UINT64_FMT    "I64"

#define SHUT_WR     1
#define snprintf    _snprintf
#define vsnprintf   _vsnprintf
#define sleep(x)    Sleep((x) * 1000)

#define popen(x, y)   _popen(x, y)
#define pclose(x)   _pclose(x)
#define close(x)    _close(x)
#define dlsym(x,y)    GetProcAddress((HINSTANCE) (x), (y))
#define RTLD_LAZY   0
#define fseeko(x, y, z)   fseek((x), (y), (z))
#define write(x, y, z)    _write((x), (y), (unsigned) z)
#define read(x, y, z)   _read((x), (y), (unsigned) z)
#define flockfile(x)    (void) 0
#define funlockfile(x)    (void) 0

#ifdef HAVE_STRTOUI64
#define strtoull(x, y, z) _strtoui64(x, y, z)
#else
#define strtoull(x, y, z) strtoul(x, y, z)
#endif /* HAVE_STRTOUI64 */

#if !defined(fileno)
#define fileno(x)   _fileno(x)
#endif /* !fileno MINGW #defines fileno */

typedef HANDLE pthread_mutex_t;
typedef HANDLE pthread_cond_t;
typedef DWORD pthread_t;
typedef HANDLE pid_t;

struct timespec {
  long tv_nsec;
  long tv_sec;
};

static int pthread_mutex_lock(pthread_mutex_t *);
static int pthread_mutex_unlock(pthread_mutex_t *);

#if defined(HAVE_STDINT)
#include <stdint.h>
#else
typedef unsigned int    uint32_t;
typedef unsigned short    uint16_t;
#if _MSC_VER > 1200
typedef unsigned __int64  uint64_t;
#else
/* VC6 cannot cast double to unsigned __int64, needed by print_dir_entry() */
typedef __int64 uint64_t;
#endif /* _MSC_VER */
#endif /* HAVE_STDINT */

/*
 * POSIX dirent interface
 */
struct dirent {
  char  d_name[FILENAME_MAX];
};

typedef struct DIR {
  HANDLE      handle;
  WIN32_FIND_DATAW  info;
  struct dirent   result;
} DIR;

#else       /* UNIX  specific */
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <sys/mman.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>

#include <pwd.h>
#include <unistd.h>
#include <dirent.h>
#include <dlfcn.h>
#include <pthread.h>
#define SSL_LIB     "libssl.so"
#define CRYPTO_LIB    "libcrypto.so"
#define DIRSEP      '/'
#define IS_DIRSEP_CHAR(c) ((c) == '/')
#define O_BINARY    0
#define closesocket(a)    close(a)
#define mg_fopen(x, y)    fopen(x, y)
#define mg_mkdir(x, y)    mkdir(x, y)
#define mg_remove(x)    remove(x)
#define mg_rename(x, y)   rename(x, y)
#define mg_getcwd(x, y)   getcwd(x, y)
#define ERRNO     errno
#define INVALID_SOCKET    (-1)
#define UINT64_FMT    "j"
typedef int SOCKET;

#endif /* End of Windows and UNIX specific includes */

#include "mongoose.h"

#define MONGOOSE_VERSION  "2.8"
#define PASSWORDS_FILE_NAME ".htpasswd"
#define CGI_ENVIRONMENT_SIZE  (64 * 1024)
#define MAX_CGI_ENVIR_VARS  64
#define MAX_REQUEST_SIZE  (64 * 1024)
#define MAX_REQUEST_SIZE_PRINT (8 * 1024 * 1024)
#define MAX_LISTENING_SOCKETS 10
// Increased from default of 32
#define MAX_CALLBACKS   64
#define ARRAY_SIZE(array) (sizeof(array) / sizeof(array[0]))
#define UNKNOWN_CONTENT_LENGTH  ((uint64_t) ~0)
#define DEBUG_MGS_PREFIX  "*** Mongoose debug *** "

#if defined(DEBUG)
#define DEBUG_TRACE(x) do {printf x; putchar('\n'); fflush(stdout);} while (0)
#else
#define DEBUG_TRACE(x)
#endif /* DEBUG */

/*
 * Darwin prior to 7.0 and Win32 do not have socklen_t
 */
#ifdef NO_SOCKLEN_T
typedef int socklen_t;
#endif /* NO_SOCKLEN_T */

#if !defined(FALSE)
enum {FALSE, TRUE};
#endif /* !FALSE */

typedef int bool_t;
typedef void * (*mg_thread_func_t)(void *);

static const char *http_500_error = "Internal Server Error";

/*
 * Snatched from OpenSSL includes. I put the prototypes here to be independent
 * from the OpenSSL source installation. Having this, mongoose + SSL can be
 * built on any system with binary SSL libraries installed.
 */
typedef struct ssl_st SSL;
typedef struct ssl_method_st SSL_METHOD;
typedef struct ssl_ctx_st SSL_CTX;

#define SSL_ERROR_WANT_READ 2
#define SSL_ERROR_WANT_WRITE  3
#define SSL_FILETYPE_PEM  1
#define CRYPTO_LOCK   1

/*
 * Dynamically loaded SSL functionality
 */
struct ssl_func {
  const char  *name;    /* SSL function name  */
  void    (*ptr)(void); /* Function pointer */
};

#define SSL_free(x) (* (void (*)(SSL *)) ssl_sw[0].ptr)(x)
#define SSL_accept(x) (* (int (*)(SSL *)) ssl_sw[1].ptr)(x)
#define SSL_connect(x)  (* (int (*)(SSL *)) ssl_sw[2].ptr)(x)
#define SSL_read(x,y,z) (* (int (*)(SSL *, void *, int))    \
        ssl_sw[3].ptr)((x),(y),(z))
#define SSL_write(x,y,z) (* (int (*)(SSL *, const void *,int))    \
        ssl_sw[4].ptr)((x), (y), (z))
#define SSL_get_error(x,y)(* (int (*)(SSL *, int)) ssl_sw[5])((x), (y))
#define SSL_set_fd(x,y) (* (int (*)(SSL *, SOCKET)) ssl_sw[6].ptr)((x), (y))
#define SSL_new(x)  (* (SSL * (*)(SSL_CTX *)) ssl_sw[7].ptr)(x)
#define SSL_CTX_new(x)  (* (SSL_CTX * (*)(SSL_METHOD *)) ssl_sw[8].ptr)(x)
#define SSLv23_server_method()  (* (SSL_METHOD * (*)(void)) ssl_sw[9].ptr)()
#define SSL_library_init() (* (int (*)(void)) ssl_sw[10].ptr)()
#define SSL_CTX_use_PrivateKey_file(x,y,z)  (* (int (*)(SSL_CTX *, \
    const char *, int)) ssl_sw[11].ptr)((x), (y), (z))
#define SSL_CTX_use_certificate_file(x,y,z) (* (int (*)(SSL_CTX *, \
    const char *, int)) ssl_sw[12].ptr)((x), (y), (z))
#define SSL_CTX_set_default_passwd_cb(x,y) \
  (* (void (*)(SSL_CTX *, mg_spcb_t)) ssl_sw[13].ptr)((x),(y))
#define SSL_CTX_free(x) (* (void (*)(SSL_CTX *)) ssl_sw[14].ptr)(x)

#define CRYPTO_num_locks() (* (int (*)(void)) crypto_sw[0].ptr)()
#define CRYPTO_set_locking_callback(x)          \
    (* (void (*)(void (*)(int, int, const char *, int)))  \
    crypto_sw[1].ptr)(x)
#define CRYPTO_set_id_callback(x)         \
  (* (void (*)(unsigned long (*)(void))) crypto_sw[2].ptr)(x)

/*
 * set_ssl_option() function when called, updates this array.
 * It loads SSL library dynamically and changes NULLs to the actual addresses
 * of respective functions. The macros above (like SSL_connect()) are really
 * just calling these functions indirectly via the pointer.
 */
static struct ssl_func  ssl_sw[] = {
  {"SSL_free",      NULL},
  {"SSL_accept",      NULL},
  {"SSL_connect",     NULL},
  {"SSL_read",      NULL},
  {"SSL_write",     NULL},
  {"SSL_get_error",   NULL},
  {"SSL_set_fd",      NULL},
  {"SSL_new",     NULL},
  {"SSL_CTX_new",     NULL},
  {"SSLv23_server_method",  NULL},
  {"SSL_library_init",    NULL},
  {"SSL_CTX_use_PrivateKey_file", NULL},
  {"SSL_CTX_use_certificate_file",NULL},
  {"SSL_CTX_set_default_passwd_cb",NULL},
  {"SSL_CTX_free",    NULL},
  {NULL,        NULL}
};

/*
 * Similar array as ssl_sw. These functions are located in different lib.
 */
static struct ssl_func  crypto_sw[] = {
  {"CRYPTO_num_locks",    NULL},
  {"CRYPTO_set_locking_callback", NULL},
  {"CRYPTO_set_id_callback",  NULL},
  {NULL,        NULL}
};

/*
 * Month names
 */
static const char *month_names[] = {
  "Jan", "Feb", "Mar", "Apr", "May", "Jun",
  "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};

/*
 * Unified socket address. For IPv6 support, add IPv6 address structure
 * in the union u.
 */
struct usa {
  socklen_t len;
  union {
    struct sockaddr sa;
    struct sockaddr_in sin;
  } u;
};

/*
 * Specifies a string (chunk of memory).
 * Used to traverse comma separated lists of options.
 */
struct vec {
  const char  *ptr;
  size_t    len;
};

/*
 * Structure used by mg_stat() function. Uses 64 bit file length.
 */
struct mgstat {
  bool_t    is_directory; /* Directory marker   */
  uint64_t  size;   /* File size      */
  time_t    mtime;    /* Modification time    */
};

struct mg_option {
  const char  *name;
  const char  *description;
  const char  *default_value;
  int   index;
  bool_t (*setter)(struct mg_context *, const char *);
};

/*
 * Numeric indexes for the option values in context, ctx->options
 */
enum mg_option_index {
  OPT_ROOT, OPT_INDEX_FILES, OPT_PORTS, OPT_DIR_LIST, OPT_CGI_EXTENSIONS,
  OPT_CGI_INTERPRETER, OPT_CGI_ENV, OPT_SSI_EXTENSIONS, OPT_AUTH_DOMAIN,
  OPT_AUTH_GPASSWD, OPT_AUTH_PUT, OPT_ACCESS_LOG, OPT_ERROR_LOG,
  OPT_SSL_CERTIFICATE, OPT_ALIASES, OPT_ACL, OPT_UID, OPT_PROTECT,
  OPT_SERVICE, OPT_HIDE, OPT_ADMIN_URI, OPT_MAX_THREADS, OPT_IDLE_TIME,
  OPT_MIME_TYPES,
  NUM_OPTIONS
};

/*
 * Structure used to describe listening socket, or socket which was
 * accept()-ed by the master thread and queued for future handling
 * by the worker thread.
 */
struct socket {
  SOCKET    sock;   /* Listening socket   */
  struct usa  lsa;    /* Local socket address   */
  struct usa  rsa;    /* Remote socket address  */
  bool_t    is_ssl;   /* Is socket SSL-ed   */
};

/*
 * Callback function, and where it is bound to
 */
struct callback {
  char    *uri_regex; /* URI regex to handle    */
  mg_callback_t func;   /* user callback    */
  bool_t    is_auth;  /* func is auth checker   */
  int   status_code;  /* error code to handle   */
  void    *user_data; /* opaque user data   */
};

/*
 * Mongoose context
 */
struct mg_context {
  int   stop_flag;  /* Should we stop event loop  */
  SSL_CTX   *ssl_ctx; /* SSL context      */

  FILE    *access_log;  /* Opened access log    */
  FILE    *error_log; /* Opened error log   */

  struct socket listeners[MAX_LISTENING_SOCKETS];
  int   num_listeners;

  struct callback callbacks[MAX_CALLBACKS];
  int   num_callbacks;

  char    *options[NUM_OPTIONS];  /* Configured opions  */
  pthread_mutex_t opt_mutex[NUM_OPTIONS]; /* Option protector */

  int   max_threads;  /* Maximum number of threads  */
  int   num_threads;  /* Number of threads    */
  int   num_idle; /* Number of idle threads */
  pthread_mutex_t thr_mutex;  /* Protects (max|num)_threads */
  pthread_cond_t  thr_cond;
  pthread_mutex_t bind_mutex; /* Protects bind operations */

  struct socket queue[20];  /* Accepted sockets   */
  int   sq_head;  /* Head of the socket queue */
  int   sq_tail;  /* Tail of the socket queue */
  pthread_cond_t  empty_cond; /* Socket queue empty condvar */
  pthread_cond_t  full_cond;  /* Socket queue full condvar  */

  mg_spcb_t ssl_password_callback;
  mg_callback_t log_callback;
};

/*
 * Client connection.
 */
struct mg_connection {
  struct mg_request_info  request_info;
  struct mg_context *ctx;   /* Mongoose context we belong to*/
  SSL   *ssl;   /* SSL descriptor   */
  struct socket client;   /* Connected client   */
  time_t    birth_time; /* Time connection was accepted */
  bool_t    free_post_data; /* post_data was malloc-ed  */
  bool_t    embedded_auth;  /* Used for authorization */
  uint64_t  num_bytes_sent; /* Total bytes sent to client */
};

/*
 * Print error message to the opened error log stream.
 */
static void
cry(struct mg_connection *conn, const char *fmt, ...)
{
  char  buf[BUFSIZ];
  va_list ap;

  va_start(ap, fmt);
  (void) vsnprintf(buf, sizeof(buf), fmt, ap);
  conn->ctx->log_callback(conn, &conn->request_info, buf);
  va_end(ap);
}

/*
 * Return fake connection structure. Used for logging, if connection
 * is not applicable at the moment of logging.
 */
static struct mg_connection *
fc(struct mg_context *ctx)
{
  static struct mg_connection fake_connection;
  fake_connection.ctx = ctx;
  return (&fake_connection);
}

/*
 * If an embedded code does not intercept logging by calling
 * mg_set_log_callback(), this function is used for logging. It prints
 * stuff to the conn->error_log, which is stderr unless "error_log"
 * option was set.
 */
static void
builtin_error_log(struct mg_connection *conn,
    const struct mg_request_info *request_info, void *message)
{
  FILE  *fp;
  time_t  timestamp;

  fp = conn->ctx->error_log;
  flockfile(fp);

  timestamp = time(NULL);

  (void) fprintf(fp,
      "[%010lu] [error] [client %s] ",
      (unsigned long) timestamp,
      inet_ntoa(conn->client.rsa.u.sin.sin_addr));

  if (request_info->request_method != NULL)
    (void) fprintf(fp, "%s %s: ",
        request_info->request_method,
        request_info->uri);

  (void) fprintf(fp, "%s", (char *) message);

  fputc('\n', fp);

  funlockfile(fp);
}

const char *
mg_version(void)
{
  return (MONGOOSE_VERSION);
}

static void
mg_strlcpy(register char *dst, register const char *src, size_t n)
{
  for (; *src != '\0' && n > 1; n--)
    *dst++ = *src++;
  *dst = '\0';
}

static int
lowercase(const char *s)
{
  return (tolower(* (unsigned char *) s));
}

static int
mg_strncasecmp(const char *s1, const char *s2, size_t len)
{
  int diff = 0;

  if (len > 0)
    do {
      diff = lowercase(s1++) - lowercase(s2++);
    } while (diff == 0 && s1[-1] != '\0' && --len > 0);

  return (diff);
}

static int
mg_strcasecmp(const char *s1, const char *s2)
{
  int diff;

  do {
    diff = lowercase(s1++) - lowercase(s2++);
  } while (diff == 0 && s1[-1] != '\0');

  return (diff);
}

static char *
mg_strndup(const char *ptr, size_t len)
{
  char  *p;

  if ((p = (char *) malloc(len + 1)) != NULL)
    mg_strlcpy(p, ptr, len + 1);

  return (p);

}

static char *
mg_strdup(const char *str)
{
  return (mg_strndup(str, strlen(str)));
}

/*
 * Like snprintf(), but never returns negative value, or the value
 * that is larger than a supplied buffer.
 * Thanks to Adam Zeldis to pointing snprintf()-caused vulnerability
 * in his audit report.
 */
static int
mg_vsnprintf(struct mg_connection *conn,
    char *buf, size_t buflen, const char *fmt, va_list ap)
{
  int n;

  if (buflen == 0)
    return (0);

  n = vsnprintf(buf, buflen, fmt, ap);

  if (n < 0) {
    cry(conn, "vsnprintf error");
    n = 0;
  } else if (n >= (int) buflen) {
    cry(conn, "truncating vsnprintf buffer: [%.*s]",
        n > 200 ? 200 : n, buf);
    n = (int) buflen - 1;
  }
  buf[n] = '\0';

  return (n);
}

static int
mg_snprintf(struct mg_connection *conn,
    char *buf, size_t buflen, const char *fmt, ...)
{
  va_list ap;
  int n;

  va_start(ap, fmt);
  n = mg_vsnprintf(conn, buf, buflen, fmt, ap);
  va_end(ap);

  return (n);
}

/*
 * Convert string representing a boolean value to a boolean value
 */
static bool_t
is_true(const char *str)
{
  static const char *trues[] = {"1", "yes", "true", "ja", NULL};
  int     i;

  for (i = 0; trues[i] != NULL; i++)
    if (str != NULL && mg_strcasecmp(str, trues[i]) == 0)
      return (TRUE);

  return (FALSE);
}

/*
 * Skip the characters until one of the delimiters characters found.
 * 0-terminate resulting word. Skip the rest of the delimiters if any.
 * Advance pointer to buffer to the next word. Return found 0-terminated word.
 */
static char *
skip(char **buf, const char *delimiters)
{
  char  *p, *begin_word, *end_word, *end_delimiters;

  begin_word = *buf;
  end_word = begin_word + strcspn(begin_word, delimiters);
  end_delimiters = end_word + strspn(end_word, delimiters);

  for (p = end_word; p < end_delimiters; p++)
    *p = '\0';

  *buf = end_delimiters;

  return (begin_word);
}

/*
 * Return HTTP header value, or NULL if not found.
 */
static const char *
get_header(const struct mg_request_info *ri, const char *name)
{
  int i;

  for (i = 0; i < ri->num_headers; i++)
    if (!mg_strcasecmp(name, ri->http_headers[i].name))
      return (ri->http_headers[i].value);

  return (NULL);
}

const char *
mg_get_header(const struct mg_connection *conn, const char *name)
{
  return (get_header(&conn->request_info, name));
}

/*
 * A helper function for traversing comma separated list of values.
 * It returns a list pointer shifted to the next value, of NULL if the end
 * of the list found.
 * Value is stored in val vector. If value has form "x=y", then eq_val
 * vector is initialized to point to the "y" part, and val vector length
 * is adjusted to point only to "x".
 */
static const char *
next_option(const char *list, struct vec *val, struct vec *eq_val)
{
  if (list == NULL || *list == '\0') {
    /* End of the list */
    list = NULL;
  } else {
    val->ptr = list;
    if ((list = strchr(val->ptr, ',')) != NULL) {
      /* Comma found. Store length and shift the list ptr */
      val->len = list - val->ptr;
      list++;
    } else {
      /* This value is the last one */
      list = val->ptr + strlen(val->ptr);
      val->len = list - val->ptr;
    }

    if (eq_val != NULL) {
      /*
       * Value has form "x=y", adjust pointers and lengths
       * so that val points to "x", and eq_val points to "y".
       */
      eq_val->len = 0;
      eq_val->ptr = memchr(val->ptr, '=', val->len);
      if (eq_val->ptr != NULL) {
        eq_val->ptr++;  /* Skip over '=' character */
        eq_val->len = val->ptr + val->len - eq_val->ptr;
        val->len = (eq_val->ptr - val->ptr) - 1;
      }
    }
  }

  return (list);
}

#if !(defined(NO_CGI) && defined(NO_SSI))
/*
 * Verify that given file has certain extension
 */
static bool_t
match_extension(const char *path, const char *ext_list)
{
  struct vec  ext_vec;
  size_t    path_len;

  path_len = strlen(path);

  while ((ext_list = next_option(ext_list, &ext_vec, NULL)) != NULL)
    if (ext_vec.len < path_len &&
        mg_strncasecmp(path + path_len - ext_vec.len,
          ext_vec.ptr, ext_vec.len) == 0)
      return (TRUE);

  return (FALSE);
}
#endif /* !(NO_CGI && NO_SSI) */

/*
 * Return TRUE if "uri" matches "regexp".
 * '*' in the regexp means zero or more characters.
 */
static bool_t
match_regex(const char *uri, const char *regexp)
{
  if (*regexp == '\0')
    return (*uri == '\0');

  if (*regexp == '*')
    do {
      if (match_regex(uri, regexp + 1))
        return (TRUE);
    } while (*uri++ != '\0');

  if (*uri != '\0' && *regexp == *uri)
    return (match_regex(uri + 1, regexp + 1));

  return (FALSE);
}

static const struct callback *
find_callback(struct mg_context *ctx, bool_t is_auth,
    const char *uri, int status_code)
{
  const struct callback *cb, *found;
  int     i;

  found = NULL;
  pthread_mutex_lock(&ctx->bind_mutex);
  for (i = 0; i < ctx->num_callbacks; i++) {
    cb = ctx->callbacks + i;
    if ((uri != NULL && cb->uri_regex != NULL &&
        ((is_auth && cb->is_auth) || (!is_auth && !cb->is_auth)) &&
        match_regex(uri, cb->uri_regex)) || (uri == NULL &&
         (cb->status_code == 0 ||
          cb->status_code == status_code))) {
      found = cb;
      break;
    }
  }
  pthread_mutex_unlock(&ctx->bind_mutex);

  return (found);
}

/*
 * For use by external application. This sets custom logging function.
 */
void
mg_set_log_callback(struct mg_context *ctx, mg_callback_t log_callback)
{
  /* If NULL is specified as a callback, revert back to the default */
  if (log_callback == NULL)
    ctx->log_callback = &builtin_error_log;
  else
    ctx->log_callback = log_callback;
}

/*
 * Send error message back to the client.
 */
static void
send_error(struct mg_connection *conn, int status, const char *reason,
    const char *fmt, ...)
{
  const struct callback *cb;
  char    buf[BUFSIZ];
  va_list   ap;
  int   len;

  conn->request_info.status_code = status;

  /* If error handler is set, call it. Otherwise, send error message */
  if ((cb = find_callback(conn->ctx, FALSE, NULL, status)) != NULL) {
    cb->func(conn, &conn->request_info, cb->user_data);
  } else {
    buf[0] = '\0';
    len = 0;

    /* Errors 1xx, 204 and 304 MUST NOT send a body */
    if (status > 199 && status != 204 && status != 304) {
      len = mg_snprintf(conn, buf, sizeof(buf),
          "Error %d: %s\n", status, reason);
      cry(conn, "%s", buf);

      va_start(ap, fmt);
      len += mg_vsnprintf(conn, buf + len, sizeof(buf) - len,
          fmt, ap);
      va_end(ap);
      conn->num_bytes_sent = len;
    }

    (void) mg_printf(conn,
        "HTTP/1.1 %d %s\r\n"
        "Content-Type: text/plain\r\n"
        "Content-Length: %d\r\n"
        "Connection: close\r\n"
        "\r\n%s", status, reason, len, buf);
  }
}

#ifdef _WIN32
static int
pthread_mutex_init(pthread_mutex_t *mutex, void *unused)
{
  unused = NULL;
  *mutex = CreateMutex(NULL, FALSE, NULL);
  return (*mutex == NULL ? -1 : 0);
}

static int
pthread_mutex_destroy(pthread_mutex_t *mutex)
{
  return (CloseHandle(*mutex) == 0 ? -1 : 0);
}

static int
pthread_mutex_lock(pthread_mutex_t *mutex)
{
  return (WaitForSingleObject(*mutex, INFINITE) == WAIT_OBJECT_0? 0 : -1);
}

static int
pthread_mutex_unlock(pthread_mutex_t *mutex)
{
  return (ReleaseMutex(*mutex) == 0 ? -1 : 0);
}

static int
pthread_cond_init(pthread_cond_t *cv, const void *unused)
{
  unused = NULL;
  *cv = CreateEvent(NULL, FALSE, FALSE, NULL);
  return (*cv == NULL ? -1 : 0);
}

static int
pthread_cond_timedwait(pthread_cond_t *cv, pthread_mutex_t *mutex,
  const struct timespec *ts)
{
  DWORD status;
  DWORD msec = INFINITE;
  time_t  now;

  if (ts != NULL) {
    now = time(NULL);
    msec = (DWORD)(1000 * (now > ts->tv_sec ? 0 : ts->tv_sec - now));
  }

  (void) ReleaseMutex(*mutex);
  status = WaitForSingleObject(*cv, msec);
  (void) WaitForSingleObject(*mutex, INFINITE);

  return (status == WAIT_OBJECT_0 ? 0 : -1);
}

static int
pthread_cond_wait(pthread_cond_t *cv, pthread_mutex_t *mutex)
{
  return (pthread_cond_timedwait(cv, mutex, NULL));
}

static int
pthread_cond_signal(pthread_cond_t *cv)
{
  return (SetEvent(*cv) == 0 ? -1 : 0);
}

static int
pthread_cond_destroy(pthread_cond_t *cv)
{
  return (CloseHandle(*cv) == 0 ? -1 : 0);
}

static pthread_t
pthread_self(void)
{
  return (GetCurrentThreadId());
}

/*
 * Change all slashes to backslashes. It is Windows.
 */
static void
fix_directory_separators(char *path)
{
  int i;

  for (i = 0; path[i] != '\0'; i++) {
    if (path[i] == '/')
      path[i] = '\\';
    /* i > 0 check is to preserve UNC paths, \\server\file.txt */
    if (path[i] == '\\' && i > 0)
      while (path[i + 1] == '\\' || path[i + 1] == '/')
        (void) memmove(path + i + 1,
            path + i + 2, strlen(path + i + 1));
  }
}

/*
 * Encode 'path' which is assumed UTF-8 string, into UNICODE string.
 * wbuf and wbuf_len is a target buffer and its length.
 */
static void
to_unicode(const char *path, wchar_t *wbuf, size_t wbuf_len)
{
  char  buf[FILENAME_MAX], *p;

  mg_strlcpy(buf, path, sizeof(buf));
  fix_directory_separators(buf);

  /* Point p to the end of the file name */
  p = buf + strlen(buf) - 1;

  /* Trim trailing backslash character */
  while (p > buf && *p == '\\' && p[-1] != ':')
    *p-- = '\0';

  /*
   * Protect from CGI code disclosure.
   * This is very nasty hole. Windows happily opens files with
   * some garbage in the end of file name. So fopen("a.cgi    ", "r")
   * actually opens "a.cgi", and does not return an error!
   */
  if (*p == 0x20 || *p == 0x2e || *p == 0x2b || (*p & ~0x7f)) {
    (void) fprintf(stderr, "Rejecting suspicious path: [%s]", buf);
    buf[0] = '\0';
  }

  (void) MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, (int) wbuf_len);
}

#if defined(_WIN32_WCE)

static time_t
time(time_t *ptime)
{
  time_t    t;
  SYSTEMTIME  st;
  FILETIME  ft;

  GetSystemTime(&st);
  SystemTimeToFileTime(&st, &ft);
  t = SYS2UNIX_TIME(ft.dwLowDateTime, ft.dwHighDateTime);

  if (ptime != NULL)
    *ptime = t;

  return (t);
}

static time_t
mktime(struct tm *ptm)
{
  SYSTEMTIME  st;
  FILETIME  ft, lft;

  st.wYear = ptm->tm_year + 1900;
  st.wMonth = ptm->tm_mon + 1;
  st.wDay = ptm->tm_mday;
  st.wHour = ptm->tm_hour;
  st.wMinute = ptm->tm_min;
  st.wSecond = ptm->tm_sec;
  st.wMilliseconds = 0;

  SystemTimeToFileTime(&st, &ft);
  LocalFileTimeToFileTime(&ft, &lft);
  return (time_t)((MAKEUQUAD(lft.dwLowDateTime, lft.dwHighDateTime) -
      EPOCH_DIFF) / RATE_DIFF);
}

static struct tm *
localtime(const time_t *ptime, struct tm *ptm)
{
  uint64_t  t = ((uint64_t)*ptime) * RATE_DIFF + EPOCH_DIFF;
  FILETIME  ft, lft;
  SYSTEMTIME  st;
  TIME_ZONE_INFORMATION tzinfo;

  if (ptm == NULL)
    return NULL;

  * (uint64_t *) &ft = t;
  FileTimeToLocalFileTime(&ft, &lft);
  FileTimeToSystemTime(&lft, &st);
  ptm->tm_year = st.wYear - 1900;
  ptm->tm_mon = st.wMonth - 1;
  ptm->tm_wday = st.wDayOfWeek;
  ptm->tm_mday = st.wDay;
  ptm->tm_hour = st.wHour;
  ptm->tm_min = st.wMinute;
  ptm->tm_sec = st.wSecond;
  ptm->tm_yday = 0; // hope nobody uses this
  ptm->tm_isdst = ((GetTimeZoneInformation(&tzinfo) ==
      TIME_ZONE_ID_DAYLIGHT) ? 1 : 0);

  return ptm;
}

static size_t
strftime(char *dst, size_t dst_size, const char *fmt, const struct tm *tm)
{
  (void) snprintf(dst, dst_size, "implement strftime() for WinCE");
  return (0);

#endif

static int
mg_rename(const char* oldname, const char* newname)
{
  wchar_t woldbuf[FILENAME_MAX];
  wchar_t wnewbuf[FILENAME_MAX];

  to_unicode(oldname, woldbuf, ARRAY_SIZE(woldbuf));
  to_unicode(newname, wnewbuf, ARRAY_SIZE(wnewbuf));

  return (MoveFileW(woldbuf, wnewbuf) ? 0 : -1);
}


static FILE *
mg_fopen(const char *path, const char *mode)
{
  wchar_t wbuf[FILENAME_MAX], wmode[20];

  to_unicode(path, wbuf, ARRAY_SIZE(wbuf));
  MultiByteToWideChar(CP_UTF8, 0, mode, -1, wmode, ARRAY_SIZE(wmode));

  return (_wfopen(wbuf, wmode));
}

static int
mg_stat(const char *path, struct mgstat *stp)
{
  int       ok = -1; /* Error */
  wchar_t       wbuf[FILENAME_MAX];
  WIN32_FILE_ATTRIBUTE_DATA info;

  to_unicode(path, wbuf, ARRAY_SIZE(wbuf));

  if (GetFileAttributesExW(wbuf, GetFileExInfoStandard, &info) != 0) {
    stp->size = MAKEUQUAD(info.nFileSizeLow, info.nFileSizeHigh);
    stp->mtime = SYS2UNIX_TIME(info.ftLastWriteTime.dwLowDateTime,
        info.ftLastWriteTime.dwHighDateTime);
    stp->is_directory =
        info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;
    ok = 0;  /* Success */
  }

  return (ok);
}

static int
mg_remove(const char *path)
{
  wchar_t wbuf[FILENAME_MAX];

  to_unicode(path, wbuf, ARRAY_SIZE(wbuf));

  return (DeleteFileW(wbuf) ? 0 : -1);
}

static int
mg_mkdir(const char *path, int mode)
{
  char  buf[FILENAME_MAX];
  wchar_t wbuf[FILENAME_MAX];

  mode = 0; /* Unused */
  mg_strlcpy(buf, path, sizeof(buf));
  fix_directory_separators(buf);

  (void) MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, sizeof(wbuf));

  return (CreateDirectoryW(wbuf, NULL) ? 0 : -1);
}

static char *
mg_getcwd(char *buf, int buf_len)
{
  wchar_t   wbuf[FILENAME_MAX], *basename;

  if (GetModuleFileNameW(NULL, wbuf, ARRAY_SIZE(wbuf))) {
    if ((basename = wcsrchr(wbuf, DIRSEP)) != NULL) {
      *basename = L'\0';
      if (WideCharToMultiByte(CP_UTF8, 0, wbuf, -1, buf,
          buf_len, NULL, NULL) > 0)
        return (buf);
    }
  }

  return (NULL);
}

/*
 * Implementation of POSIX opendir/closedir/readdir for Windows.
 */
static DIR *
opendir(const char *name)
{
  DIR *dir = NULL;
  wchar_t wpath[FILENAME_MAX];
  DWORD attrs;

  if (name == NULL) {
    SetLastError(ERROR_BAD_ARGUMENTS);
  } else if ((dir = (DIR *) malloc(sizeof(*dir))) == NULL) {
    SetLastError(ERROR_NOT_ENOUGH_MEMORY);
  } else {
    to_unicode(name, wpath, ARRAY_SIZE(wpath));
    attrs = GetFileAttributesW(wpath);
    if (attrs != 0xFFFFFFFF &&
        ((attrs & FILE_ATTRIBUTE_DIRECTORY) == FILE_ATTRIBUTE_DIRECTORY)) {
      (void) wcscat(wpath, L"\\*");
      dir->handle = FindFirstFileW(wpath, &dir->info);
      dir->result.d_name[0] = '\0';
    } else {
      free(dir);
      dir = NULL;
    }
  }

  return (dir);
}

static int
closedir(DIR *dir)
{
  int result = 0;

  if (dir != NULL) {
    if (dir->handle != INVALID_HANDLE_VALUE)
      result = FindClose(dir->handle) ? 0 : -1;

    free(dir);
  } else {
    result = -1;
    SetLastError(ERROR_BAD_ARGUMENTS);
  }

  return (result);
}

struct dirent *
readdir(DIR *dir)
{
  struct dirent *result = 0;

  if (dir) {
    if (dir->handle != INVALID_HANDLE_VALUE) {
      result = &dir->result;
      (void) WideCharToMultiByte(CP_UTF8, 0,
          dir->info.cFileName, -1, result->d_name,
          sizeof(result->d_name), NULL, NULL);

      if (!FindNextFileW(dir->handle, &dir->info)) {
        (void) FindClose(dir->handle);
        dir->handle = INVALID_HANDLE_VALUE;
      }

    } else {
      SetLastError(ERROR_FILE_NOT_FOUND);
    }
  } else {
    SetLastError(ERROR_BAD_ARGUMENTS);
  }

  return (result);
}

#define set_close_on_exec(fd) /* No FD_CLOEXEC on Windows */

static int
start_thread(struct mg_context *ctx, mg_thread_func_t func, void *param)
{
  HANDLE  hThread;

  ctx = NULL; /* Unused */

  hThread = CreateThread(NULL, 0,
      (LPTHREAD_START_ROUTINE) func, param, 0, NULL);

  if (hThread != NULL)
    (void) CloseHandle(hThread);

  return (hThread == NULL ? -1 : 0);
}

static HANDLE
dlopen(const char *dll_name, int flags)
{
  wchar_t wbuf[FILENAME_MAX];

  flags = 0; /* Unused */
  to_unicode(dll_name, wbuf, ARRAY_SIZE(wbuf));

  return (LoadLibraryW(wbuf));
}

#if !defined(NO_CGI)
static int
kill(pid_t pid, int sig_num)
{
  (void) TerminateProcess(pid, sig_num);
  (void) CloseHandle(pid);
  return (0);
}

static pid_t
spawn_process(struct mg_connection *conn, const char *prog, char *envblk,
    char *envp[], int fd_stdin, int fd_stdout, const char *dir)
{
  HANDLE  me;
  char  *p, *interp, cmdline[FILENAME_MAX], line[FILENAME_MAX];
  FILE  *fp;
  STARTUPINFOA    si;
  PROCESS_INFORMATION pi;

  envp = NULL; /* Unused */

  (void) memset(&si, 0, sizeof(si));
  (void) memset(&pi, 0, sizeof(pi));

  /* XXX redirect CGI errors to the error log file */
  si.cb   = sizeof(si);
  si.dwFlags  = STARTF_USESTDHANDLES | STARTF_USESHOWWINDOW;
  si.wShowWindow  = SW_HIDE;

  me = GetCurrentProcess();
  (void) DuplicateHandle(me, (HANDLE) _get_osfhandle(fd_stdin), me,
      &si.hStdInput, 0, TRUE, DUPLICATE_SAME_ACCESS);
  (void) DuplicateHandle(me, (HANDLE) _get_osfhandle(fd_stdout), me,
      &si.hStdOutput, 0, TRUE, DUPLICATE_SAME_ACCESS);

  /* If CGI file is a script, try to read the interpreter line */
  interp = conn->ctx->options[OPT_CGI_INTERPRETER];
  if (interp == NULL) {
    line[2] = '\0';
    (void) mg_snprintf(conn, cmdline, sizeof(cmdline), "%s%c%s",
        dir, DIRSEP, prog);
    if ((fp = fopen(cmdline, "r")) != NULL) {
      (void) fgets(line, sizeof(line), fp);
      if (memcmp(line, "#!", 2) != 0)
        line[2] = '\0';
      /* Trim whitespaces from interpreter name */
      for (p = &line[strlen(line) - 1]; p > line &&
          isspace(*p); p--)
        *p = '\0';
      (void) fclose(fp);
    }
    interp = line + 2;
  }

  if ((p = (char *) strrchr(prog, '/')) != NULL)
    prog = p + 1;

  (void) mg_snprintf(conn, cmdline, sizeof(cmdline), "%s%s%s",
      interp, interp[0] == '\0' ? "" : " ", prog);

  (void) mg_snprintf(conn, line, sizeof(line), "%s", dir);
  fix_directory_separators(line);

  DEBUG_TRACE((DEBUG_MGS_PREFIX "%s: Running [%s]", __func__, cmdline));
  if (CreateProcessA(NULL, cmdline, NULL, NULL, TRUE,
      CREATE_NEW_PROCESS_GROUP, envblk, line, &si, &pi) == 0) {
    cry(conn, "%s: CreateProcess(%s): %d",
        __func__, cmdline, ERRNO);
    pi.hProcess = (pid_t) -1;
  } else {
    (void) close(fd_stdin);
    (void) close(fd_stdout);
  }

  (void) CloseHandle(si.hStdOutput);
  (void) CloseHandle(si.hStdInput);
  (void) CloseHandle(pi.hThread);

  return ((pid_t) pi.hProcess);
}

static int
pipe(int *fds)
{
  return (_pipe(fds, BUFSIZ, _O_BINARY));
}
#endif /* !NO_CGI */

static int
set_non_blocking_mode(struct mg_connection *conn, SOCKET sock)
{
  unsigned long on = 1;

  conn = NULL; /* unused */
  return (ioctlsocket(sock, FIONBIO, &on));
}

#else

static int
mg_stat(const char *path, struct mgstat *stp)
{
  struct stat st;
  int   ok;

  if (stat(path, &st) == 0) {
    ok = 0;
    stp->size = st.st_size;
    stp->mtime = st.st_mtime;
    stp->is_directory = S_ISDIR(st.st_mode);
  } else {
    ok = -1;
  }

  return (ok);
}

static void
set_close_on_exec(int fd)
{
  (void) fcntl(fd, F_SETFD, FD_CLOEXEC);
}

static int
start_thread(struct mg_context *ctx, mg_thread_func_t func, void *param)
{
  pthread_t thread_id;
  pthread_attr_t  attr;
  int   retval;

  (void) pthread_attr_init(&attr);
  (void) pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);

  if ((retval = pthread_create(&thread_id, &attr, func, param)) != 0)
    cry(fc(ctx), "%s: %s", __func__, strerror(retval));

  return (retval);
}

#ifndef NO_CGI
static pid_t
spawn_process(struct mg_connection *conn, const char *prog, char *envblk,
    char *envp[], int fd_stdin, int fd_stdout, const char *dir)
{
  pid_t   pid;
  const char  *interp;

  envblk = NULL;  /* unused */

  if ((pid = fork()) == -1) {
    /* Parent */
    send_error(conn, 500, http_500_error,
        "fork(): %s", strerror(ERRNO));
  } else if (pid == 0) {
    /* Child */
    if (chdir(dir) != 0) {
      cry(conn, "%s: chdir(%s): %s",
          __func__, dir, strerror(ERRNO));
    } else if (dup2(fd_stdin, 0) == -1) {
      cry(conn, "%s: dup2(stdin, %d): %s",
          __func__, fd_stdin, strerror(ERRNO));
    } else if (dup2(fd_stdout, 1) == -1) {
      cry(conn, "%s: dup2(stdout, %d): %s",
          __func__, fd_stdout, strerror(ERRNO));
    } else {
      /* If error file is specified, send errors there */
      if (conn->ctx->error_log != NULL)
        (void) dup2(fileno(conn->ctx->error_log), 2);

      (void) close(fd_stdin);
      (void) close(fd_stdout);

      /* Execute CGI program */
      interp = conn->ctx->options[OPT_CGI_INTERPRETER];
      if (interp == NULL) {
        (void) execle(prog, prog, NULL, envp);
        cry(conn, "%s: execle(%s): %s",
            __func__, prog, strerror(ERRNO));
      } else {
        (void) execle(interp, interp, prog, NULL, envp);
        cry(conn, "%s: execle(%s %s): %s",
            __func__, interp, prog, strerror(ERRNO));
      }
    }
    exit(EXIT_FAILURE);
  } else {
    /* Parent. Close stdio descriptors */
    (void) close(fd_stdin);
    (void) close(fd_stdout);
  }

  return (pid);
}
#endif /* !NO_CGI */

static int
set_non_blocking_mode(struct mg_connection *conn, SOCKET sock)
{
  int flags, ok = -1;

  if ((flags = fcntl(sock, F_GETFL, 0)) == -1) {
    cry(conn, "%s: fcntl(F_GETFL): %d", __func__, ERRNO);
  } else if (fcntl(sock, F_SETFL, flags | O_NONBLOCK) != 0) {
    cry(conn, "%s: fcntl(F_SETFL): %d", __func__, ERRNO);
  } else {
    ok = 0; /* Success */
  }

  return (ok);
}
#endif /* _WIN32 */

static void
lock_option(struct mg_context *ctx, int opt_index)
{
  if (pthread_mutex_lock(&ctx->opt_mutex[opt_index]) != 0)
    cry(fc(ctx), "pthread_mutex_lock: %s", strerror(ERRNO));
}

static void
unlock_option(struct mg_context *ctx, int opt_index)
{
  if (pthread_mutex_unlock(&ctx->opt_mutex[opt_index]) != 0)
    cry(fc(ctx), "pthread_mutex_unlock: %s", strerror(ERRNO));
}

/*
 * Write data to the IO channel - opened file descriptor, socket or SSL
 * descriptor. Return number of bytes written.
 */
static uint64_t
push(FILE *fp, SOCKET sock, SSL *ssl, const char *buf, uint64_t len)
{
  uint64_t  sent;
  int   n, k;

  sent = 0;
  while (sent < len) {

    /* How many bytes we send in this iteration */
    k = len - sent > INT_MAX ? INT_MAX : (int) (len - sent);

    if (ssl != NULL) {
      n = SSL_write(ssl, buf + sent, k);
    } else if (fp != NULL) {
      n = fwrite(buf + sent, 1, k, fp);
      if (ferror(fp))
        n = -1;
    } else {
      n = send(sock, buf + sent, k, 0);
    }

    if (n < 0)
      break;

    sent += n;
  }

  return (sent);
}

/*
 * Read from IO channel - opened file descriptor, socket, or SSL descriptor.
 * Return number of bytes read.
 */
static int
pull(FILE *fp, SOCKET sock, SSL *ssl, char *buf, int len)
{
  int nread;

  if (ssl != NULL) {
    nread = SSL_read(ssl, buf, len);
  } else if (fp != NULL) {
    nread = fread(buf, 1, (size_t) len, fp);
    if (ferror(fp))
      nread = -1;
  } else {
    nread = recv(sock, buf, (size_t) len, 0);
  }

  return (nread);
}

int
mg_write(struct mg_connection *conn, const void *buf, int len)
{
  assert(len >= 0);
  return ((int) push(NULL, conn->client.sock, conn->ssl,
        (const char *) buf, (uint64_t) len));
}

int
mg_printf(struct mg_connection *conn, const char *fmt, ...)
{
  char*  buf;
  int len, result;
  va_list ap;
  int buffer_length = sizeof(char) * MAX_REQUEST_SIZE_PRINT;

  buf = (char*) malloc(buffer_length);
  va_start(ap, fmt);
  len = mg_vsnprintf(conn, buf, buffer_length, fmt, ap);
  va_end(ap);

  result = mg_write(conn, buf, len);
  free(buf);
  return result;
}

/*
 * Return content length of the request, or UNKNOWN_CONTENT_LENGTH constant if
 * Content-Length header is not set.
 */
static uint64_t
get_content_length(const struct mg_connection *conn)
{
  const char *cl = mg_get_header(conn, "Content-Length");
  return (cl == NULL ? UNKNOWN_CONTENT_LENGTH : strtoull(cl, NULL, 10));
}

/*
 * URL-decode input buffer into destination buffer.
 * 0-terminate the destination buffer. Return the length of decoded data.
 * form-url-encoded data differs from URI encoding in a way that it
 * uses '+' as character for space, see RFC 1866 section 8.2.1
 * http://ftp.ics.uci.edu/pub/ietf/html/rfc1866.txt
 */
static size_t
url_decode(const char *src, size_t src_len, char *dst, size_t dst_len,
    bool_t is_form_url_encoded)
{
  size_t  i, j;
  int a, b;
#define HEXTOI(x) (isdigit(x) ? x - '0' : x - 'W')

  for (i = j = 0; i < src_len && j < dst_len - 1; i++, j++) {
    if (src[i] == '%' &&
        isxdigit(* (unsigned char *) (src + i + 1)) &&
        isxdigit(* (unsigned char *) (src + i + 2))) {
      a = tolower(* (unsigned char *) (src + i + 1));
      b = tolower(* (unsigned char *) (src + i + 2));
      dst[j] = ((HEXTOI(a) << 4) | HEXTOI(b)) & 0xff;
      i += 2;
    } else if (is_form_url_encoded && src[i] == '+') {
      dst[j] = ' ';
    } else {
      dst[j] = src[i];
    }
  }

  dst[j] = '\0';  /* Null-terminate the destination */

  return (j);
}

/*
 * Search for a form variable in a given buffer.
 * Semantic is the same as for mg_get_var().
 */
static char *
get_var(const char *name, const char *buf, size_t buf_len)
{
  const char  *p, *e, *s;
  char    *val;
  size_t    var_len, len;

  var_len = strlen(name);
  e = buf + buf_len;
  val = NULL;

  /* buf is "var1=val1&var2=val2...". Find variable first */
  for (p = buf; p + var_len < e; p++)
    if ((p == buf || p[-1] == '&') && p[var_len] == '=' &&
        !mg_strncasecmp(name, p, var_len)) {

      /* Point p to variable value */
      p += var_len + 1;

      /* Point s to the end of the value */
      s = (const char *) memchr(p, '&', e - p);
      if (s == NULL)
        s = e;

      /* Try to allocate the buffer */
      len = s - p;
      if ((val = (char *) malloc(len + 1)) != NULL)
        (void) url_decode(p, len, val, len + 1, TRUE);
      break;
    }

  return (val);
}

/*
 * Free the pointer returned by mg_get_var(). This is needed for languages
 * like python, to have an ability to free allocated data without
 * loading C runtime library and calling free().
 */
void
mg_free(char *data)
{
  free(data);
}

/*
 * Return form data variable.
 * It can be specified in query string, or in the POST data.
 * Return NULL if the variable not found, or allocated 0-terminated value.
 * It is caller's responsibility to free the returned value.
 */
char *
mg_get_var(const struct mg_connection *conn, const char *name)
{
  const struct mg_request_info  *ri = &conn->request_info;
  char        *v1, *v2;

  v1 = v2 = NULL;

  /* Look in both query_string and POST data */
  if (ri->query_string != NULL)
    v1 = get_var(name, ri->query_string, strlen(ri->query_string));
  if (ri->post_data_len > 0)
    v2 = get_var(name, ri->post_data, ri->post_data_len);

  /* If they both have queried variable, POST data wins */
  if (v1 != NULL && v2 != NULL)
    free(v1);

  return (v2 == NULL ? v1 : v2);
}

/*
 * Transform URI to the file name.
 */
static void
convert_uri_to_file_name(struct mg_connection *conn, const char *uri,
    char *buf, size_t buf_len)
{
  struct mg_context *ctx = conn->ctx;
  struct vec    uri_vec, path_vec;
  const char    *list;

  lock_option(ctx, OPT_ROOT);
  mg_snprintf(conn, buf, buf_len, "%s%s", ctx->options[OPT_ROOT], uri);
  unlock_option(ctx, OPT_ROOT);

  /* If requested URI has aliased prefix, use alternate root */
  lock_option(ctx, OPT_ALIASES);
  list = ctx->options[OPT_ALIASES];

  while ((list = next_option(list, &uri_vec, &path_vec)) != NULL) {
    if (memcmp(uri, uri_vec.ptr, uri_vec.len) == 0) {
      (void) mg_snprintf(conn, buf, buf_len, "%.*s%s",
          path_vec.len, path_vec.ptr, uri + uri_vec.len);
      break;
    }
  }
  unlock_option(ctx, OPT_ALIASES);

#ifdef _WIN32
  fix_directory_separators(buf);
#endif /* _WIN32 */
}

/*
 * Setup listening socket on given address, return socket.
 * Address format: [local_ip_address:]port_number
 */
static SOCKET
mg_open_listening_port(struct mg_context *ctx, const char *str, struct usa *usa)
{
  SOCKET    sock;
  int   on = 1, a, b, c, d, port;

  /* MacOS needs that. If we do not zero it, bind() will fail. */
  (void) memset(usa, 0, sizeof(*usa));

  if (sscanf(str, "%d.%d.%d.%d:%d", &a, &b, &c, &d, &port) == 5) {
    /* IP address to bind to is specified */
    usa->u.sin.sin_addr.s_addr =
        htonl((a << 24) | (b << 16) | (c << 8) | d);
  } else if (sscanf(str, "%d", &port) == 1) {
    /* Only port number is specified. Bind to all addresses */
    usa->u.sin.sin_addr.s_addr = htonl(INADDR_ANY);
  } else {
    return (INVALID_SOCKET);
  }

  usa->len      = sizeof(usa->u.sin);
  usa->u.sin.sin_family   = AF_INET;
  usa->u.sin.sin_port   = htons((uint16_t) port);

  if ((sock = socket(PF_INET, SOCK_STREAM, 6)) != INVALID_SOCKET &&
      setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
      (char *) &on, sizeof(on)) == 0 &&
      bind(sock, &usa->u.sa, usa->len) == 0 &&
      listen(sock, 128) == 0) {
    /* Success */
    set_close_on_exec(sock);
  } else {
    /* Error */
    cry(fc(ctx), "%s(%d): %s", __func__, port, strerror(ERRNO));
    if (sock != INVALID_SOCKET)
      (void) closesocket(sock);
    sock = INVALID_SOCKET;
  }

  return (sock);
}

/*
 * Check whether full request is buffered. Return:
 *   -1         if request is malformed
 *    0         if request is not yet fully buffered
 *   >0         actual request length, including last \r\n\r\n
 */
static int
get_request_len(const char *buf, size_t buflen)
{
  const char  *s, *e;
  int   len = 0;

  for (s = buf, e = s + buflen - 1; len <= 0 && s < e; s++)
    /* Control characters are not allowed but >=128 is. */
    if (!isprint(* (unsigned char *) s) && *s != '\r' &&
        *s != '\n' && * (unsigned char *) s < 128)
      len = -1;
    else if (s[0] == '\n' && s[1] == '\n')
      len = (int) (s - buf) + 2;
    else if (s[0] == '\n' && &s[1] < e &&
        s[1] == '\r' && s[2] == '\n')
      len = (int) (s - buf) + 3;

  return (len);
}

/*
 * Convert month to the month number. Return -1 on error, or month number
 */
static int
montoi(const char *s)
{
  size_t  i;

  for (i = 0; i < sizeof(month_names) / sizeof(month_names[0]); i++)
    if (!strcmp(s, month_names[i]))
      return ((int) i);

  return (-1);
}

/*
 * Parse date-time string, and return the corresponding time_t value
 */
static time_t
date_to_epoch(const char *s)
{
  time_t    current_time;
  struct tm tm, *tmp;
  char    mon[32];
  int   sec, min, hour, mday, month, year;

  (void) memset(&tm, 0, sizeof(tm));
  sec = min = hour = mday = month = year = 0;

  if (((sscanf(s, "%d/%3s/%d %d:%d:%d",
      &mday, mon, &year, &hour, &min, &sec) == 6) ||
      (sscanf(s, "%d %3s %d %d:%d:%d",
      &mday, mon, &year, &hour, &min, &sec) == 6) ||
      (sscanf(s, "%*3s, %d %3s %d %d:%d:%d",
      &mday, mon, &year, &hour, &min, &sec) == 6) ||
      (sscanf(s, "%d-%3s-%d %d:%d:%d",
      &mday, mon, &year, &hour, &min, &sec) == 6)) &&
      (month = montoi(mon)) != -1) {
    tm.tm_mday  = mday;
    tm.tm_mon = month;
    tm.tm_year  = year;
    tm.tm_hour  = hour;
    tm.tm_min = min;
    tm.tm_sec = sec;
  }

  if (tm.tm_year > 1900)
    tm.tm_year -= 1900;
  else if (tm.tm_year < 70)
    tm.tm_year += 100;

  /* Set Daylight Saving Time field */
  current_time = time(NULL);
  tmp = localtime(&current_time);
  tm.tm_isdst = tmp->tm_isdst;

  return (mktime(&tm));
}

/*
 * Protect against directory disclosure attack by removing '..',
 * excessive '/' and '\' characters
 */
static void
remove_double_dots_and_double_slashes(char *s)
{
  char  *p = s;

  while (*s != '\0') {
    *p++ = *s++;
    if (s[-1] == '/' || s[-1] == '\\') {
      /* Skip all following slashes and backslashes */
      while (*s == '/' || *s == '\\')
        s++;

      /* Skip all double-dots */
      while (*s == '.' && s[1] == '.')
        s += 2;
    }
  }
  *p = '\0';
}

/*
 * Built-in mime types
 */
static const struct {
  const char  *extension;
  size_t    ext_len;
  const char  *mime_type;
  size_t    mime_type_len;
} mime_types[] = {
  {".html", 5,  "text/html",      9},
  {".htm",  4,  "text/html",      9},
  {".shtm", 5,  "text/html",      9},
  {".shtml",  6,  "text/html",      9},
  {".css",  4,  "text/css",     8},
  {".js",   3,  "application/x-javascript", 24},
  {".ico",  4,  "image/x-icon",     12},
  {".gif",  4,  "image/gif",      9},
  {".jpg",  4,  "image/jpeg",     10},
  {".jpeg", 5,  "image/jpeg",     10},
  {".png",  4,  "image/png",      9},
  {".svg",  4,  "image/svg+xml",    13},
  {".torrent",  8,  "application/x-bittorrent", 24},
  {".wav",  4,  "audio/x-wav",      11},
  {".mp3",  4,  "audio/x-mp3",      11},
  {".mid",  4,  "audio/mid",      9},
  {".m3u",  4,  "audio/x-mpegurl",    15},
  {".ram",  4,  "audio/x-pn-realaudio",   20},
  {".ra",   3,  "audio/x-pn-realaudio",   20},
  {".doc",  4,  "application/msword",   19},
  {".exe",  4,  "application/octet-stream", 24},
  {".zip",  4,  "application/x-zip-compressed", 28},
  {".xls",  4,  "application/excel",    17},
  {".tgz",  4,  "application/x-tar-gz",   20},
  {".tar",  4,  "application/x-tar",    17},
  {".gz",   3,  "application/x-gunzip",   20},
  {".arj",  4,  "application/x-arj-compressed", 28},
  {".rar",  4,  "application/x-arj-compressed", 28},
  {".rtf",  4,  "application/rtf",    15},
  {".pdf",  4,  "application/pdf",    15},
  {".swf",  4,  "application/x-shockwave-flash",29},
  {".mpg",  4,  "video/mpeg",     10},
  {".mpeg", 5,  "video/mpeg",     10},
  {".asf",  4,  "video/x-ms-asf",   14},
  {".avi",  4,  "video/x-msvideo",    15},
  {".bmp",  4,  "image/bmp",      9},
  {NULL,    0,  NULL,       0}
};

/*
 * Look at the "path" extension and figure what mime type it has.
 * Store mime type in the vector.
 */
static void
get_mime_type(struct mg_context *ctx, const char *path, struct vec *vec)
{
  struct vec  ext_vec, mime_vec;
  const char  *list, *ext;
  size_t    i, path_len;

  path_len = strlen(path);

  /*
   * Scan user-defined mime types first, in case user wants to
   * override default mime types.
   */
  lock_option(ctx, OPT_MIME_TYPES);
  list = ctx->options[OPT_MIME_TYPES];
  while ((list = next_option(list, &ext_vec, &mime_vec)) != NULL) {
    /* ext now points to the path suffix */
    ext = path + path_len - ext_vec.len;
    if (mg_strncasecmp(ext, ext_vec.ptr, ext_vec.len) == 0) {
      *vec = mime_vec;
      unlock_option(ctx, OPT_MIME_TYPES);
      return;
    }
  }
  unlock_option(ctx, OPT_MIME_TYPES);

  /* Now scan built-in mime types */
  for (i = 0; mime_types[i].extension != NULL; i++) {
    ext = path + (path_len - mime_types[i].ext_len);
    if (path_len > mime_types[i].ext_len &&
        mg_strcasecmp(ext, mime_types[i].extension) == 0) {
      vec->ptr = mime_types[i].mime_type;
      vec->len = mime_types[i].mime_type_len;
      return;
    }
  }

  /* Nothing found. Fall back to text/plain */
  vec->ptr = "text/plain";
  vec->len = 10;
}

#ifndef HAVE_MD5
typedef struct MD5Context {
  uint32_t  buf[4];
  uint32_t  bits[2];
  unsigned char in[64];
} MD5_CTX;

#if __BYTE_ORDER == 1234
#define byteReverse(buf, len) /* Nothing */
#else
/*
 * Note: this code is harmless on little-endian machines.
 */
static void
byteReverse(unsigned char *buf, unsigned longs)
{
  uint32_t t;
  do {
    t = (uint32_t) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
      ((unsigned) buf[1] << 8 | buf[0]);
    *(uint32_t *) buf = t;
    buf += 4;
  } while (--longs);
}
#endif /* __BYTE_ORDER */

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
static void
MD5Init(MD5_CTX *ctx)
{
  ctx->buf[0] = 0x67452301;
  ctx->buf[1] = 0xefcdab89;
  ctx->buf[2] = 0x98badcfe;
  ctx->buf[3] = 0x10325476;

  ctx->bits[0] = 0;
  ctx->bits[1] = 0;
}

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
static void
MD5Transform(uint32_t buf[4], uint32_t const in[16])
{
  register uint32_t a, b, c, d;

  a = buf[0];
  b = buf[1];
  c = buf[2];
  d = buf[3];

  MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
  MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
  MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
  MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
  MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
  MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
  MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
  MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
  MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
  MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
  MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
  MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
  MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
  MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
  MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
  MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

  MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
  MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
  MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
  MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
  MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
  MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
  MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
  MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
  MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
  MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
  MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
  MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
  MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
  MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
  MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
  MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

  MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
  MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
  MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
  MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
  MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
  MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
  MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
  MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
  MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
  MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
  MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
  MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
  MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
  MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
  MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
  MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

  MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
  MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
  MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
  MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
  MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
  MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
  MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
  MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
  MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
  MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
  MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
  MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
  MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
  MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
  MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
  MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

  buf[0] += a;
  buf[1] += b;
  buf[2] += c;
  buf[3] += d;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
static void
MD5Update(MD5_CTX *ctx, unsigned char const *buf, unsigned len)
{
  uint32_t t;

  /* Update bitcount */

  t = ctx->bits[0];
  if ((ctx->bits[0] = t + ((uint32_t) len << 3)) < t)
    ctx->bits[1]++;   /* Carry from low to high */
  ctx->bits[1] += len >> 29;

  t = (t >> 3) & 0x3f;  /* Bytes already in shsInfo->data */

  /* Handle any leading odd-sized chunks */

  if (t) {
    unsigned char *p = (unsigned char *) ctx->in + t;

    t = 64 - t;
    if (len < t) {
      memcpy(p, buf, len);
      return;
    }
    memcpy(p, buf, t);
    byteReverse(ctx->in, 16);
    MD5Transform(ctx->buf, (uint32_t *) ctx->in);
    buf += t;
    len -= t;
  }
  /* Process data in 64-byte chunks */

  while (len >= 64) {
    memcpy(ctx->in, buf, 64);
    byteReverse(ctx->in, 16);
    MD5Transform(ctx->buf, (uint32_t *) ctx->in);
    buf += 64;
    len -= 64;
  }

  /* Handle any remaining bytes of data. */

  memcpy(ctx->in, buf, len);
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
static void
MD5Final(unsigned char digest[16], MD5_CTX *ctx)
{
  unsigned count;
  unsigned char *p;

  /* Compute number of bytes mod 64 */
  count = (ctx->bits[0] >> 3) & 0x3F;

  /* Set the first char of padding to 0x80.  This is safe since there is
     always at least one byte free */
  p = ctx->in + count;
  *p++ = 0x80;

  /* Bytes of padding needed to make 64 bytes */
  count = 64 - 1 - count;

  /* Pad out to 56 mod 64 */
  if (count < 8) {
    /* Two lots of padding:  Pad the first block to 64 bytes */
    memset(p, 0, count);
    byteReverse(ctx->in, 16);
    MD5Transform(ctx->buf, (uint32_t *) ctx->in);

    /* Now fill the next block with 56 bytes */
    memset(ctx->in, 0, 56);
  } else {
    /* Pad block to 56 bytes */
    memset(p, 0, count - 8);
  }
  byteReverse(ctx->in, 14);

  /* Append length in bits and transform */
  ((uint32_t *) ctx->in)[14] = ctx->bits[0];
  ((uint32_t *) ctx->in)[15] = ctx->bits[1];

  MD5Transform(ctx->buf, (uint32_t *) ctx->in);
  byteReverse((unsigned char *) ctx->buf, 4);
  memcpy(digest, ctx->buf, 16);
  memset((char *) ctx, 0, sizeof(ctx)); /* In case it's sensitive */
}
#endif /* !HAVE_MD5 */

/*
 * Stringify binary data. Output buffer must be twice as big as input,
 * because each byte takes 2 bytes in string representation
 */
static void
bin2str(char *to, const unsigned char *p, size_t len)
{
  static const char *hex = "0123456789abcdef";

  for (; len--; p++) {
    *to++ = hex[p[0] >> 4];
    *to++ = hex[p[0] & 0x0f];
  }
  *to = '\0';
}

/*
 * Return stringified MD5 hash for list of vectors.
 * buf must point to 33-bytes long buffer
 */
static void
mg_md5(char *buf, ...)
{
  unsigned char hash[16];
  const char  *p;
  va_list   ap;
  MD5_CTX   ctx;

  MD5Init(&ctx);

  va_start(ap, buf);
  while ((p = va_arg(ap, const char *)) != NULL)
    MD5Update(&ctx, (unsigned char *) p, (int) strlen(p));
  va_end(ap);

  MD5Final(hash, &ctx);
  bin2str(buf, hash, sizeof(hash));
}

/*
 * Check the user's password, return 1 if OK
 */
static bool_t
check_password(const char *method, const char *ha1, const char *uri,
    const char *nonce, const char *nc, const char *cnonce,
    const char *qop, const char *response)
{
  char  ha2[32 + 1], expected_response[32 + 1];

  /* XXX  Due to a bug in MSIE, we do not compare the URI  */
  /* Also, we do not check for authentication timeout */
  if (/*strcmp(dig->uri, c->ouri) != 0 || */
      strlen(response) != 32 /*||
      now - strtoul(dig->nonce, NULL, 10) > 3600 */)
    return (FALSE);

  mg_md5(ha2, method, ":", uri, NULL);
  mg_md5(expected_response, ha1, ":", nonce, ":", nc,
      ":", cnonce, ":", qop, ":", ha2, NULL);

  return (!mg_strcasecmp(response, expected_response));
}

/*
 * Use the global passwords file, if specified by auth_gpass option,
 * or search for .htpasswd in the requested directory.
 */
static FILE *
open_auth_file(struct mg_connection *conn, const char *path)
{
  struct mg_context *ctx = conn->ctx;
  char      name[FILENAME_MAX];
  const char    *p, *e;
  struct mgstat   st;
  FILE      *fp;

  if (ctx->options[OPT_AUTH_GPASSWD] != NULL) {
    /* Use global passwords file */
    fp =  mg_fopen(ctx->options[OPT_AUTH_GPASSWD], "r");
    if (fp == NULL)
      cry(fc(ctx), "fopen(%s): %s",
          ctx->options[OPT_AUTH_GPASSWD], strerror(ERRNO));
  } else if (!mg_stat(path, &st) && st.is_directory) {
    (void) mg_snprintf(conn, name, sizeof(name), "%s%c%s",
        path, DIRSEP, PASSWORDS_FILE_NAME);
    fp = mg_fopen(name, "r");
  } else {
    /*
     * Try to find .htpasswd in requested directory.
     * Given the path, create the path to .htpasswd file
     * in the same directory. Find the right-most
     * directory separator character first. That would be the
     * directory name. If directory separator character is not
     * found, 'e' will point to 'p'.
     */
    for (p = path, e = p + strlen(p) - 1; e > p; e--)
      if (IS_DIRSEP_CHAR(*e))
        break;

    /*
     * Make up the path by concatenating directory name and
     * .htpasswd file name.
     */
    (void) mg_snprintf(conn, name, sizeof(name), "%.*s%c%s",
        (int) (e - p), p, DIRSEP, PASSWORDS_FILE_NAME);
    fp = mg_fopen(name, "r");
  }

  return (fp);
}

/*
 * Parsed Authorization: header
 */
struct ah {
  char  *user, *uri, *cnonce, *response, *qop, *nc, *nonce;
};

static bool_t
parse_auth_header(struct mg_connection *conn, char *buf, size_t buf_size,
    struct ah *ah)
{
  char    *name, *value, *s;
  const char  *auth_header;

  if ((auth_header = mg_get_header(conn, "Authorization")) == NULL ||
      mg_strncasecmp(auth_header, "Digest ", 7) != 0)
    return (FALSE);

  /* Make modifiable copy of the auth header */
  (void) mg_strlcpy(buf, auth_header + 7, buf_size);

  s = buf;
  (void) memset(ah, 0, sizeof(*ah));

  /* Gobble initial spaces */
  while (isspace(* (unsigned char *) s))
    s++;

  /* Parse authorization header */
  for (;;) {
    name = skip(&s, "=");
    value = skip(&s, ", ");

    if (*value == '"') {
      value++;
      value[strlen(value) - 1] = '\0';
    } else if (*value == '\0') {
      break;
    }

    if (!strcmp(name, "username")) {
      ah->user = value;
    } else if (!strcmp(name, "cnonce")) {
      ah->cnonce = value;
    } else if (!strcmp(name, "response")) {
      ah->response = value;
    } else if (!strcmp(name, "uri")) {
      ah->uri = value;
    } else if (!strcmp(name, "qop")) {
      ah->qop = value;
    } else if (!strcmp(name, "nc")) {
      ah->nc = value;
    } else if (!strcmp(name, "nonce")) {
      ah->nonce = value;
    }
  }

  /* CGI needs it as REMOTE_USER */
  if (ah->user != NULL)
    conn->request_info.remote_user = mg_strdup(ah->user);

  return (TRUE);
}

/*
 * Authorize against the opened passwords file. Return 1 if authorized.
 */
static bool_t
authorize(struct mg_connection *conn, FILE *fp)
{
  struct ah ah;
  char    line[256], f_user[256], domain[256], ha1[256],
      buf[MAX_REQUEST_SIZE];
  if (!parse_auth_header(conn, buf, sizeof(buf), &ah))     return (FALSE);

  /* Loop over passwords file */
  while (fgets(line, sizeof(line), fp) != NULL) {

    if (sscanf(line, "%[^:]:%[^:]:%s", f_user, domain, ha1) != 3)
      continue;

    if (!strcmp(ah.user, f_user) &&
        !strcmp(domain, conn->ctx->options[OPT_AUTH_DOMAIN]))
      return (check_password(
          conn->request_info.request_method, ha1,
          ah.uri, ah.nonce, ah.nc, ah.cnonce,
          ah.qop, ah.response));
  }

  return (FALSE);
}

/*
 * Return TRUE if request is authorised, FALSE otherwise.
 */
static bool_t
check_authorization(struct mg_connection *conn, const char *path)
{
  FILE    *fp;
  char    fname[FILENAME_MAX];
  struct vec  uri_vec, filename_vec;
  const char  *list;
  bool_t    authorized;

  fp = NULL;
  authorized = TRUE;

  lock_option(conn->ctx, OPT_PROTECT);
  list = conn->ctx->options[OPT_PROTECT];
  while ((list = next_option(list, &uri_vec, &filename_vec)) != NULL) {
    if (!memcmp(conn->request_info.uri, uri_vec.ptr, uri_vec.len)) {
      (void) mg_snprintf(conn, fname, sizeof(fname), "%.*s",
          filename_vec.len, filename_vec.ptr);
      if ((fp = mg_fopen(fname, "r")) == NULL)
        cry(conn, "%s: cannot open %s: %s",
            __func__, fname, strerror(errno));
      break;
    }
  }
  unlock_option(conn->ctx, OPT_PROTECT);

  if (fp == NULL)
    fp = open_auth_file(conn, path);

  if (fp != NULL) {
    authorized = authorize(conn, fp);
    (void) fclose(fp);
  }

  return (authorized);
}

static void
send_authorization_request(struct mg_connection *conn)
{
  conn->request_info.status_code = 401;
  (void) mg_printf(conn,
      "HTTP/1.1 401 Unauthorized\r\n"
      "WWW-Authenticate: Digest qop=\"auth\", "
      "realm=\"%s\", nonce=\"%lu\"\r\n\r\n",
      conn->ctx->options[OPT_AUTH_DOMAIN], (unsigned long) time(NULL));
}

static bool_t
is_authorized_for_put(struct mg_connection *conn)
{
  FILE  *fp;
  int ret = FALSE;

  if ((fp = mg_fopen(conn->ctx->options[OPT_AUTH_PUT], "r")) != NULL) {
    set_close_on_exec(fileno(fp));
    ret = authorize(conn, fp);
    (void) fclose(fp);
  }

  return (ret);
}

int
mg_modify_passwords_file(struct mg_context *ctx, const char *fname,
    const char *user, const char *pass)
{
  int   found;
  char    line[512], u[512], d[512], ha1[33], tmp[FILENAME_MAX];
  const char  *domain;
  FILE    *fp, *fp2;

  found = 0;
  fp = fp2 = NULL;
  domain = ctx->options[OPT_AUTH_DOMAIN];

  /* Regard empty password as no password - remove user record. */
  if (pass[0] == '\0')
    pass = NULL;

  (void) snprintf(tmp, sizeof(tmp), "%s.tmp", fname);

  /* Create the file if does not exist */
  if ((fp = mg_fopen(fname, "a+")) != NULL)
    (void) fclose(fp);

  /* Open the given file and temporary file */
  if ((fp = mg_fopen(fname, "r")) == NULL) {
    cry(fc(ctx), "Cannot open %s: %s", fname, strerror(errno));
    return (0);
  } else if ((fp2 = mg_fopen(tmp, "w+")) == NULL) {
    cry(fc(ctx), "Cannot open %s: %s", tmp, strerror(errno));
    return (0);
  }

  /* Copy the stuff to temporary file */
  while (fgets(line, sizeof(line), fp) != NULL) {

    if (sscanf(line, "%[^:]:%[^:]:%*s", u, d) != 2)
      continue;

    if (!strcmp(u, user) && !strcmp(d, domain)) {
      found++;
      if (pass != NULL) {
        mg_md5(ha1, user, ":", domain, ":", pass, NULL);
        fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
      }
    } else {
      (void) fprintf(fp2, "%s", line);
    }
  }

  /* If new user, just add it */
  if (!found && pass != NULL) {
    mg_md5(ha1, user, ":", domain, ":", pass, NULL);
    (void) fprintf(fp2, "%s:%s:%s\n", user, domain, ha1);
  }

  /* Close files */
  (void) fclose(fp);
  (void) fclose(fp2);

  /* Put the temp file in place of real file */
  (void) mg_remove(fname);
  (void) mg_rename(tmp, fname);

  return (0);
}

struct de {
  struct mg_connection  *conn;
  char      *file_name;
  struct mgstat   st;
};

/*
 * This function is called from send_directory() and prints out
 * single directory entry.
 */
static void
print_dir_entry(struct de *de)
{
  char    size[64], mod[64];

  if (de->st.is_directory) {
    (void) mg_snprintf(de->conn,
        size, sizeof(size), "%s", "[DIRECTORY]");
  } else {
    /*
     * We use (signed) cast below because MSVC 6 compiler cannot
     * convert unsigned __int64 to double. Sigh.
     */
    if (de->st.size < 1024)
      (void) mg_snprintf(de->conn, size, sizeof(size),
          "%lu", (unsigned long) de->st.size);
    else if (de->st.size < 1024 * 1024)
      (void) mg_snprintf(de->conn, size, sizeof(size),
          "%.1fk", (double) de->st.size / 1024.0);
    else if (de->st.size < 1024 * 1024 * 1024)
      (void) mg_snprintf(de->conn, size, sizeof(size),
          "%.1fM", (double) de->st.size / 1048576);
    else
      (void) mg_snprintf(de->conn, size, sizeof(size),
        "%.1fG", (double) de->st.size / 1073741824);
  }
  (void) strftime(mod, sizeof(mod), "%d-%b-%Y %H:%M",
    localtime(&de->st.mtime));
  de->conn->num_bytes_sent += mg_printf(de->conn,
      "<tr><td><a href=\"%s%s\">%s%s</a></td>"
      "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
      de->conn->request_info.uri, de->file_name, de->file_name,
      de->st.is_directory ? "/" : "", mod, size);
}

/*
 * This function is called from send_directory() and used for
 * sorting direcotory entries by size, or name, or modification time.
 */
static int
compare_dir_entries(const void *p1, const void *p2)
{
  const struct de *a = (struct de *) p1, *b = (struct de *) p2;
  const char  *query_string = a->conn->request_info.query_string;
  int   cmp_result = 0;

  if (query_string == NULL)
    query_string = "na";

  if (a->st.is_directory && !b->st.is_directory) {
    return (-1);  /* Always put directories on top */
  } else if (!a->st.is_directory && b->st.is_directory) {
    return (1);   /* Always put directories on top */
  } else if (*query_string == 'n') {
    cmp_result = strcmp(a->file_name, b->file_name);
  } else if (*query_string == 's') {
    cmp_result = a->st.size == b->st.size ? 0 :
      a->st.size > b->st.size ? 1 : -1;
  } else if (*query_string == 'd') {
    cmp_result = a->st.mtime == b->st.mtime ? 0 :
      a->st.mtime > b->st.mtime ? 1 : -1;
  }

  return (query_string[1] == 'd' ? -cmp_result : cmp_result);
}

/*
 * Send directory contents.
 */
static void
send_directory(struct mg_connection *conn, const char *dir)
{
  struct dirent *dp;
  DIR   *dirp;
  struct de *entries = NULL;
  char    path[FILENAME_MAX];
  int   i, sort_direction, num_entries = 0, arr_size = 128;

  if ((dirp = opendir(dir)) == NULL) {
    send_error(conn, 500, "Cannot open directory",
        "Error: opendir(%s): %s", path, strerror(ERRNO));
    return;
  }

  (void) mg_printf(conn, "%s",
      "HTTP/1.1 200 OK\r\n"
      "Connection: close\r\n"
      "Content-Type: text/html; charset=utf-8\r\n\r\n");

  sort_direction = conn->request_info.query_string != NULL &&
      conn->request_info.query_string[1] == 'd' ? 'a' : 'd';

  while ((dp = readdir(dirp)) != NULL) {

    /* Do not show current dir and passwords file */
    if (!strcmp(dp->d_name, ".") ||
        !strcmp(dp->d_name, "..") ||
        !strcmp(dp->d_name, PASSWORDS_FILE_NAME))
      continue;

    if (entries == NULL || num_entries >= arr_size) {
      arr_size *= 2;
      entries = (struct de *) realloc(entries,
          arr_size * sizeof(entries[0]));
    }

    if (entries == NULL) {
      send_error(conn, 500, "Cannot open directory",
          "%s", "Error: cannot allocate memory");
      return;
    }

    (void) mg_snprintf(conn, path, sizeof(path), "%s%c%s",
        dir, DIRSEP, dp->d_name);

    (void) mg_stat(path, &entries[num_entries].st);
    entries[num_entries].conn = conn;
    entries[num_entries].file_name = mg_strdup(dp->d_name);
    num_entries++;
  }
  (void) closedir(dirp);

  conn->num_bytes_sent += mg_printf(conn,
      "<html><head><title>Index of %s</title>"
      "<style>th {text-align: left;}</style></head>"
      "<body><h1>Index of %s</h1><pre><table cellpadding=\"0\">"
      "<tr><th><a href=\"?n%c\">Name</a></th>"
      "<th><a href=\"?d%c\">Modified</a></th>"
      "<th><a href=\"?s%c\">Size</a></th></tr>"
      "<tr><td colspan=\"3\"><hr></td></tr>",
      conn->request_info.uri, conn->request_info.uri,
      sort_direction, sort_direction, sort_direction);

  /* Print first entry - link to a parent directory */
  conn->num_bytes_sent += mg_printf(conn,
      "<tr><td><a href=\"%s%s\">%s</a></td>"
      "<td>&nbsp;%s</td><td>&nbsp;&nbsp;%s</td></tr>\n",
      conn->request_info.uri, "..", "Parent directory", "-", "-");

  /* Sort and print directory entries */
  qsort(entries, num_entries, sizeof(entries[0]), compare_dir_entries);
  for (i = 0; i < num_entries; i++) {
    print_dir_entry(&entries[i]);
    free(entries[i].file_name);
  }
  free(entries);

  conn->num_bytes_sent += mg_printf(conn, "%s", "</table></body></html>");
  conn->request_info.status_code = 200;
}

/*
 * Send len bytes from the opened file to the client.
 */
static void
send_opened_file_stream(struct mg_connection *conn, FILE *fp, uint64_t len)
{
  char  buf[BUFSIZ];
  int to_read, num_read, num_written;

  while (len > 0) {
    /* Calculate how much to read from the file in the buffer */
    to_read = sizeof(buf);
    if ((uint64_t) to_read > len)
      to_read = (int) len;

    /* Read from file, exit the loop on error */
    if ((num_read = fread(buf, 1, to_read, fp)) == 0)
      break;

    /* Send read bytes to the client, exit the loop on error */
    if ((num_written = mg_write(conn, buf, num_read)) != num_read)
      break;

    /* Both read and were successful, adjust counters */
    conn->num_bytes_sent += num_written;
    len -= num_written;
  }
}

/*
 * Send regular file contents.
 */
static void
send_file(struct mg_connection *conn, const char *path, struct mgstat *stp)
{
  char    date[64], lm[64], etag[64], range[64];
  const char  *fmt = "%a, %d %b %Y %H:%M:%S %Z", *msg = "OK", *hdr;
  time_t    curtime = time(NULL);
  uint64_t  cl, r1, r2;
  struct vec  mime_vec;
  FILE    *fp;
  int   n;

  get_mime_type(conn->ctx, path, &mime_vec);
  cl = stp->size;
  conn->request_info.status_code = 200;
  range[0] = '\0';

  if ((fp = mg_fopen(path, "rb")) == NULL) {
    send_error(conn, 500, http_500_error,
        "fopen(%s): %s", path, strerror(ERRNO));
    return;
  }
  set_close_on_exec(fileno(fp));

  /* If Range: header specified, act accordingly */
  r1 = r2 = 0;
  hdr = mg_get_header(conn, "Range");
  if (hdr != NULL && (n = sscanf(hdr,
      "bytes=%" UINT64_FMT "u-%" UINT64_FMT "u", &r1, &r2)) > 0) {
    conn->request_info.status_code = 206;
    (void) fseeko(fp, (off_t) r1, SEEK_SET);
    cl = n == 2 ? r2 - r1 + 1: cl - r1;
    (void) m