tor/src/common/util.h

/* Copyright (c) 2003-2004, Roger Dingledine
 * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
 * Copyright (c) 2007-2015, The Tor Project, Inc. */
/* See LICENSE for licensing information */

/**
 * \file util.h
 * \brief Headers for util.c
 **/

#ifndef TOR_UTIL_H
#define TOR_UTIL_H

#include "orconfig.h"
#include "torint.h"
#include "compat.h"
#include "di_ops.h"
#include "testsupport.h"
#include <stdio.h>
#include <stdlib.h>
#ifdef _WIN32
/* for the correct alias to struct stat */
#include <sys/stat.h>
#endif

#ifndef O_BINARY
#define O_BINARY 0
#endif
#ifndef O_TEXT
#define O_TEXT 0
#endif

/* Replace assert() with a variant that sends failures to the log before
 * calling assert() normally.
 */
#ifdef NDEBUG
/* Nobody should ever want to build with NDEBUG set.  99% of our asserts will
 * be outside the critical path anyway, so it's silly to disable bug-checking
 * throughout the entire program just because a few asserts are slowing you
 * down.  Profile, optimize the critical path, and keep debugging on.
 *
 * And I'm not just saying that because some of our asserts check
 * security-critical properties.
 */
#error "Sorry; we don't support building with NDEBUG."
#endif

/* Don't use assertions during coverage. It leads to tons of unreached
 * branches which in reality are only assertions we didn't hit. */
#ifdef TOR_COVERAGE
#define tor_assert(a) STMT_BEGIN                                        \
  (void)(a);                                                            \
  STMT_END
#else
/** Like assert(3), but send assertion failures to the log as well as to
 * stderr. */
#define tor_assert(expr) STMT_BEGIN                                     \
  if (PREDICT_UNLIKELY(!(expr))) {                                      \
    tor_assertion_failed_(SHORT_FILE__, __LINE__, __func__, #expr);     \
    abort();                                                            \
  } STMT_END
#endif

void tor_assertion_failed_(const char *fname, unsigned int line,
                           const char *func, const char *expr);

/* If we're building with dmalloc, we want all of our memory allocation
 * functions to take an extra file/line pair of arguments.  If not, not.
 * We define DMALLOC_PARAMS to the extra parameters to insert in the
 * function prototypes, and DMALLOC_ARGS to the extra arguments to add
 * to calls. */
#ifdef USE_DMALLOC
#define DMALLOC_PARAMS , const char *file, const int line
#define DMALLOC_ARGS , SHORT_FILE__, __LINE__
#else
#define DMALLOC_PARAMS
#define DMALLOC_ARGS
#endif

/** Define this if you want Tor to crash when any problem comes up,
 * so you can get a coredump and track things down. */
// #define tor_fragile_assert() tor_assert(0)
#define tor_fragile_assert()

/* Memory management */
void *tor_malloc_(size_t size DMALLOC_PARAMS) ATTR_MALLOC;
void *tor_malloc_zero_(size_t size DMALLOC_PARAMS) ATTR_MALLOC;
void *tor_calloc_(size_t nmemb, size_t size DMALLOC_PARAMS) ATTR_MALLOC;
void *tor_realloc_(void *ptr, size_t size DMALLOC_PARAMS);
void *tor_reallocarray_(void *ptr, size_t size1, size_t size2 DMALLOC_PARAMS);
char *tor_strdup_(const char *s DMALLOC_PARAMS) ATTR_MALLOC ATTR_NONNULL((1));
char *tor_strndup_(const char *s, size_t n DMALLOC_PARAMS)
  ATTR_MALLOC ATTR_NONNULL((1));
void *tor_memdup_(const void *mem, size_t len DMALLOC_PARAMS)
  ATTR_MALLOC ATTR_NONNULL((1));
void *tor_memdup_nulterm_(const void *mem, size_t len DMALLOC_PARAMS)
  ATTR_MALLOC ATTR_NONNULL((1));
void tor_free_(void *mem);
#ifdef USE_DMALLOC
extern int dmalloc_free(const char *file, const int line, void *pnt,
                        const int func_id);
#define tor_free(p) STMT_BEGIN \
    if (PREDICT_LIKELY((p)!=NULL)) {                \
      dmalloc_free(SHORT_FILE__, __LINE__, (p), 0); \
      (p)=NULL;                                     \
    }                                               \
  STMT_END
#else
/** Release memory allocated by tor_malloc, tor_realloc, tor_strdup, etc.
 * Unlike the free() function, tor_free() will still work on NULL pointers,
 * and it sets the pointer value to NULL after freeing it.
 *
 * This is a macro.  If you need a function pointer to release memory from
 * tor_malloc(), use tor_free_().
 */
#define tor_free(p) STMT_BEGIN                                 \
    if (PREDICT_LIKELY((p)!=NULL)) {                           \
      free(p);                                                 \
      (p)=NULL;                                                \
    }                                                          \
  STMT_END
#endif

#define tor_malloc(size)       tor_malloc_(size DMALLOC_ARGS)
#define tor_malloc_zero(size)  tor_malloc_zero_(size DMALLOC_ARGS)
#define tor_calloc(nmemb,size) tor_calloc_(nmemb, size DMALLOC_ARGS)
#define tor_realloc(ptr, size) tor_realloc_(ptr, size DMALLOC_ARGS)
#define tor_reallocarray(ptr, sz1, sz2) \
  tor_reallocarray_((ptr), (sz1), (sz2) DMALLOC_ARGS)
#define tor_strdup(s)          tor_strdup_(s DMALLOC_ARGS)
#define tor_strndup(s, n)      tor_strndup_(s, n DMALLOC_ARGS)
#define tor_memdup(s, n)       tor_memdup_(s, n DMALLOC_ARGS)
#define tor_memdup_nulterm(s, n)       tor_memdup_nulterm_(s, n DMALLOC_ARGS)

void tor_log_mallinfo(int severity);

/** Return the offset of <b>member</b> within the type <b>tp</b>, in bytes */
#if defined(__GNUC__) && __GNUC__ > 3
#define STRUCT_OFFSET(tp, member) __builtin_offsetof(tp, member)
#else
 #define STRUCT_OFFSET(tp, member) \
   ((off_t) (((char*)&((tp*)0)->member)-(char*)0))
#endif

/** Macro: yield a pointer to the field at position <b>off</b> within the
 * structure <b>st</b>.  Example:
 * <pre>
 *   struct a { int foo; int bar; } x;
 *   off_t bar_offset = STRUCT_OFFSET(struct a, bar);
 *   int *bar_p = STRUCT_VAR_P(&x, bar_offset);
 *   *bar_p = 3;
 * </pre>
 */
#define STRUCT_VAR_P(st, off) ((void*) ( ((char*)(st)) + (off) ) )

/** Macro: yield a pointer to an enclosing structure given a pointer to
 * a substructure at offset <b>off</b>. Example:
 * <pre>
 *   struct base { ... };
 *   struct subtype { int x; struct base b; } x;
 *   struct base *bp = &x.base;
 *   struct *sp = SUBTYPE_P(bp, struct subtype, b);
 * </pre>
 */
#define SUBTYPE_P(p, subtype, basemember) \
  ((void*) ( ((char*)(p)) - STRUCT_OFFSET(subtype, basemember) ))

/* Logic */
/** Macro: true if two values have the same boolean value. */
#define bool_eq(a,b) (!(a)==!(b))
/** Macro: true if two values have different boolean values. */
#define bool_neq(a,b) (!(a)!=!(b))

/* Math functions */
double tor_mathlog(double d) ATTR_CONST;
long tor_lround(double d) ATTR_CONST;
int64_t tor_llround(double d) ATTR_CONST;
int tor_log2(uint64_t u64) ATTR_CONST;
uint64_t round_to_power_of_2(uint64_t u64);
unsigned round_to_next_multiple_of(unsigned number, unsigned divisor);
uint32_t round_uint32_to_next_multiple_of(uint32_t number, uint32_t divisor);
uint64_t round_uint64_to_next_multiple_of(uint64_t number, uint64_t divisor);
int64_t round_int64_to_next_multiple_of(int64_t number, int64_t divisor);
int64_t sample_laplace_distribution(double mu, double b, double p);
int64_t add_laplace_noise(int64_t signal, double random, double delta_f,
                          double epsilon);
int n_bits_set_u8(uint8_t v);
int64_t clamp_double_to_int64(double number);

/* Compute the CEIL of <b>a</b> divided by <b>b</b>, for nonnegative <b>a</b>
 * and positive <b>b</b>.  Works on integer types only. Not defined if a+b can
 * overflow. */
#define CEIL_DIV(a,b) (((a)+(b)-1)/(b))

/* Return <b>v</b> if it's between <b>min</b> and <b>max</b>.  Otherwise
 * return <b>min</b> if <b>v</b> is smaller than <b>min</b>, or <b>max</b> if
 * <b>b</b> is larger than <b>max</b>.
 *
 * Requires that <b>min</b> is no more than <b>max</b>. May evaluate any of
 * its arguments more than once! */
#define CLAMP(min,v,max)                        \
  ( ((v) < (min)) ? (min) :                     \
    ((v) > (max)) ? (max) :                     \
    (v) )

/* String manipulation */

/** Allowable characters in a hexadecimal string. */
#define HEX_CHARACTERS "0123456789ABCDEFabcdef"
void tor_strlower(char *s) ATTR_NONNULL((1));
void tor_strupper(char *s) ATTR_NONNULL((1));
int tor_strisprint(const char *s) ATTR_NONNULL((1));
int tor_strisnonupper(const char *s) ATTR_NONNULL((1));
int strcmp_opt(const char *s1, const char *s2);
int strcmpstart(const char *s1, const char *s2) ATTR_NONNULL((1,2));
int strcmp_len(const char *s1, const char *s2, size_t len) ATTR_NONNULL((1,2));
int strcasecmpstart(const char *s1, const char *s2) ATTR_NONNULL((1,2));
int strcmpend(const char *s1, const char *s2) ATTR_NONNULL((1,2));
int strcasecmpend(const char *s1, const char *s2) ATTR_NONNULL((1,2));
int fast_memcmpstart(const void *mem, size_t memlen, const char *prefix);

void tor_strstrip(char *s, const char *strip) ATTR_NONNULL((1,2));
long tor_parse_long(const char *s, int base, long min,
                    long max, int *ok, char **next);
unsigned long tor_parse_ulong(const char *s, int base, unsigned long min,
                              unsigned long max, int *ok, char **next);
double tor_parse_double(const char *s, double min, double max, int *ok,
                        char **next);
uint64_t tor_parse_uint64(const char *s, int base, uint64_t min,
                         uint64_t max, int *ok, char **next);
const char *hex_str(const char *from, size_t fromlen) ATTR_NONNULL((1));
const char *eat_whitespace(const char *s);
const char *eat_whitespace_eos(const char *s, const char *eos);
const char *eat_whitespace_no_nl(const char *s);
const char *eat_whitespace_eos_no_nl(const char *s, const char *eos);
const char *find_whitespace(const char *s);
const char *find_whitespace_eos(const char *s, const char *eos);
const char *find_str_at_start_of_line(const char *haystack,
                                      const char *needle);
int string_is_C_identifier(const char *string);
int string_is_key_value(int severity, const char *string);
int string_is_valid_hostname(const char *string);
int string_is_valid_ipv4_address(const char *string);
int string_is_valid_ipv6_address(const char *string);

int tor_mem_is_zero(const char *mem, size_t len);
int tor_digest_is_zero(const char *digest);
int tor_digest256_is_zero(const char *digest);
char *esc_for_log(const char *string) ATTR_MALLOC;
char *esc_for_log_len(const char *chars, size_t n) ATTR_MALLOC;
const char *escaped(const char *string);

char *tor_escape_str_for_pt_args(const char *string,
                                 const char *chars_to_escape);

struct smartlist_t;
int tor_vsscanf(const char *buf, const char *pattern, va_list ap) \
  CHECK_SCANF(2, 0);
int tor_sscanf(const char *buf, const char *pattern, ...)
  CHECK_SCANF(2, 3);

void smartlist_add_asprintf(struct smartlist_t *sl, const char *pattern, ...)
  CHECK_PRINTF(2, 3);
void smartlist_add_vasprintf(struct smartlist_t *sl, const char *pattern,
                             va_list args)
  CHECK_PRINTF(2, 0);

/* Time helpers */
long tv_udiff(const struct timeval *start, const struct timeval *end);
long tv_mdiff(const struct timeval *start, const struct timeval *end);
int64_t tv_to_msec(const struct timeval *tv);
int tor_timegm(const struct tm *tm, time_t *time_out);
#define RFC1123_TIME_LEN 29
void format_rfc1123_time(char *buf, time_t t);
int parse_rfc1123_time(const char *buf, time_t *t);
#define ISO_TIME_LEN 19
#define ISO_TIME_USEC_LEN (ISO_TIME_LEN+7)
void format_local_iso_time(char *buf, time_t t);
void format_iso_time(char *buf, time_t t);
void format_iso_time_nospace(char *buf, time_t t);
void format_iso_time_nospace_usec(char *buf, const struct timeval *tv);
int parse_iso_time_(const char *cp, time_t *t, int strict);
int parse_iso_time(const char *buf, time_t *t);
int parse_http_time(const char *buf, struct tm *tm);
int format_time_interval(char *out, size_t out_len, long interval);

/* Cached time */
#ifdef TIME_IS_FAST
#define approx_time() time(NULL)
#define update_approx_time(t) STMT_NIL
#else
time_t approx_time(void);
void update_approx_time(time_t now);
#endif

/* Rate-limiter */

/** A ratelim_t remembers how often an event is occurring, and how often
 * it's allowed to occur.  Typical usage is something like:
 *
   <pre>
    if (possibly_very_frequent_event()) {
      const int INTERVAL = 300;
      static ratelim_t warning_limit = RATELIM_INIT(INTERVAL);
      char *m;
      if ((m = rate_limit_log(&warning_limit, approx_time()))) {
        log_warn(LD_GENERAL, "The event occurred!%s", m);
        tor_free(m);
      }
    }
   </pre>

   As a convenience wrapper for logging, you can replace the above with:
   <pre>
   if (possibly_very_frequent_event()) {
     static ratelim_t warning_limit = RATELIM_INIT(300);
     log_fn_ratelim(&warning_limit, LOG_WARN, LD_GENERAL,
                    "The event occurred!");
   }
   </pre>
 */
typedef struct ratelim_t {
  int rate;
  time_t last_allowed;
  int n_calls_since_last_time;
} ratelim_t;

#define RATELIM_INIT(r) { (r), 0, 0 }

char *rate_limit_log(ratelim_t *lim, time_t now);

/* File helpers */
ssize_t write_all(tor_socket_t fd, const char *buf, size_t count,int isSocket);
ssize_t read_all(tor_socket_t fd, char *buf, size_t count, int isSocket);

/** Status of an I/O stream. */
enum stream_status {
  IO_STREAM_OKAY,
  IO_STREAM_EAGAIN,
  IO_STREAM_TERM,
  IO_STREAM_CLOSED
};

const char *stream_status_to_string(enum stream_status stream_status);

enum stream_status get_string_from_pipe(FILE *stream, char *buf, size_t count);

/** Return values from file_status(); see that function's documentation
 * for details. */
typedef enum { FN_ERROR, FN_NOENT, FN_FILE, FN_DIR, FN_EMPTY } file_status_t;
file_status_t file_status(const char *filename);

/** Possible behaviors for check_private_dir() on encountering a nonexistent
 * directory; see that function's documentation for details. */
typedef unsigned int cpd_check_t;
#define CPD_NONE 0
#define CPD_CREATE 1
#define CPD_CHECK 2
#define CPD_GROUP_OK 4
#define CPD_GROUP_READ 8
#define CPD_CHECK_MODE_ONLY 16
int check_private_dir(const char *dirname, cpd_check_t check,
                      const char *effective_user);

#define OPEN_FLAGS_REPLACE (O_WRONLY|O_CREAT|O_TRUNC)
#define OPEN_FLAGS_APPEND (O_WRONLY|O_CREAT|O_APPEND)
#define OPEN_FLAGS_DONT_REPLACE (O_CREAT|O_EXCL|O_APPEND|O_WRONLY)
typedef struct open_file_t open_file_t;
int start_writing_to_file(const char *fname, int open_flags, int mode,
                          open_file_t **data_out);
FILE *start_writing_to_stdio_file(const char *fname, int open_flags, int mode,
                                  open_file_t **data_out);
FILE *fdopen_file(open_file_t *file_data);
int finish_writing_to_file(open_file_t *file_data);
int abort_writing_to_file(open_file_t *file_data);
int write_str_to_file(const char *fname, const char *str, int bin);
MOCK_DECL(int,
write_bytes_to_file,(const char *fname, const char *str, size_t len,
                     int bin));
/** An ad-hoc type to hold a string of characters and a count; used by
 * write_chunks_to_file. */
typedef struct sized_chunk_t {
  const char *bytes;
  size_t len;
} sized_chunk_t;
int write_chunks_to_file(const char *fname, const struct smartlist_t *chunks,
                         int bin, int no_tempfile);
int append_bytes_to_file(const char *fname, const char *str, size_t len,
                         int bin);
int write_bytes_to_new_file(const char *fname, const char *str, size_t len,
                            int bin);

/** Flag for read_file_to_str: open the file in binary mode. */
#define RFTS_BIN            1
/** Flag for read_file_to_str: it's okay if the file doesn't exist. */
#define RFTS_IGNORE_MISSING 2

#ifndef _WIN32
struct stat;
#endif
char *read_file_to_str(const char *filename, int flags, struct stat *stat_out)
  ATTR_MALLOC;
char *read_file_to_str_until_eof(int fd, size_t max_bytes_to_read,
                                 size_t *sz_out)
  ATTR_MALLOC;
const char *parse_config_line_from_str_verbose(const char *line,
                                       char **key_out, char **value_out,
                                       const char **err_out);
#define parse_config_line_from_str(line,key_out,value_out) \
  parse_config_line_from_str_verbose((line),(key_out),(value_out),NULL)
char *expand_filename(const char *filename);
struct smartlist_t *tor_listdir(const char *dirname);
int path_is_relative(const char *filename);

/* Process helpers */
void start_daemon(void);
void finish_daemon(const char *desired_cwd);
void write_pidfile(const char *filename);

/* Port forwarding */
void tor_check_port_forwarding(const char *filename,
                               struct smartlist_t *ports_to_forward,
                               time_t now);

typedef struct process_handle_t process_handle_t;
typedef struct process_environment_t process_environment_t;
int tor_spawn_background(const char *const filename, const char **argv,
                         process_environment_t *env,
                         process_handle_t **process_handle_out);

#define SPAWN_ERROR_MESSAGE "ERR: Failed to spawn background process - code "

#ifdef _WIN32
HANDLE load_windows_system_library(const TCHAR *library_name);
#endif

int environment_variable_names_equal(const char *s1, const char *s2);

/* DOCDOC process_environment_t */
struct process_environment_t {
  /** A pointer to a sorted empty-string-terminated sequence of
   * NUL-terminated strings of the form "NAME=VALUE". */
  char *windows_environment_block;
  /** A pointer to a NULL-terminated array of pointers to
   * NUL-terminated strings of the form "NAME=VALUE". */
  char **unixoid_environment_block;
};

process_environment_t *process_environment_make(struct smartlist_t *env_vars);
void process_environment_free(process_environment_t *env);

struct smartlist_t *get_current_process_environment_variables(void);

void set_environment_variable_in_smartlist(struct smartlist_t *env_vars,
                                           const char *new_var,
                                           void (*free_old)(void*),
                                           int free_p);

/* Values of process_handle_t.status. PROCESS_STATUS_NOTRUNNING must be
 * 0 because tor_check_port_forwarding depends on this being the initial
 * statue of the static instance of process_handle_t */
#define PROCESS_STATUS_NOTRUNNING 0
#define PROCESS_STATUS_RUNNING 1
#define PROCESS_STATUS_ERROR -1

#ifdef UTIL_PRIVATE
struct waitpid_callback_t;
/** Structure to represent the state of a process with which Tor is
 * communicating. The contents of this structure are private to util.c */
struct process_handle_t {
  /** One of the PROCESS_STATUS_* values */
  int status;
#ifdef _WIN32
  HANDLE stdin_pipe;
  HANDLE stdout_pipe;
  HANDLE stderr_pipe;
  PROCESS_INFORMATION pid;
#else
  int stdin_pipe;
  int stdout_pipe;
  int stderr_pipe;
  FILE *stdin_handle;
  FILE *stdout_handle;
  FILE *stderr_handle;
  pid_t pid;
  /** If the process has not given us a SIGCHLD yet, this has the
   * waitpid_callback_t that gets invoked once it has. Otherwise this
   * contains NULL. */
  struct waitpid_callback_t *waitpid_cb;
  /** The exit status reported by waitpid. */
  int waitpid_exit_status;
#endif // _WIN32
};
#endif

/* Return values of tor_get_exit_code() */
#define PROCESS_EXIT_RUNNING 1
#define PROCESS_EXIT_EXITED 0
#define PROCESS_EXIT_ERROR -1
int tor_get_exit_code(process_handle_t *process_handle,
                      int block, int *exit_code);
int tor_split_lines(struct smartlist_t *sl, char *buf, int len);
#ifdef _WIN32
ssize_t tor_read_all_handle(HANDLE h, char *buf, size_t count,
                            const process_handle_t *process);
#else
ssize_t tor_read_all_handle(FILE *h, char *buf, size_t count,
                            const process_handle_t *process,
                            int *eof);
#endif
ssize_t tor_read_all_from_process_stdout(
    const process_handle_t *process_handle, char *buf, size_t count);
ssize_t tor_read_all_from_process_stderr(
    const process_handle_t *process_handle, char *buf, size_t count);
char *tor_join_win_cmdline(const char *argv[]);

int tor_process_get_pid(process_handle_t *process_handle);
#ifdef _WIN32
HANDLE tor_process_get_stdout_pipe(process_handle_t *process_handle);
#else
FILE *tor_process_get_stdout_pipe(process_handle_t *process_handle);
#endif

#ifdef _WIN32
MOCK_DECL(struct smartlist_t *,
tor_get_lines_from_handle,(HANDLE *handle,
                           enum stream_status *stream_status));
#else
MOCK_DECL(struct smartlist_t *,
tor_get_lines_from_handle,(FILE *handle,
                           enum stream_status *stream_status));
#endif

int
tor_terminate_process(process_handle_t *process_handle);

MOCK_DECL(void,
tor_process_handle_destroy,(process_handle_t *process_handle,
                            int also_terminate_process));

/* ===== Insecure rng */
typedef struct tor_weak_rng_t {
  uint32_t state;
} tor_weak_rng_t;

#define TOR_WEAK_RNG_INIT {383745623}
#define TOR_WEAK_RANDOM_MAX (INT_MAX)
void tor_init_weak_random(tor_weak_rng_t *weak_rng, unsigned seed);
int32_t tor_weak_random(tor_weak_rng_t *weak_rng);
int32_t tor_weak_random_range(tor_weak_rng_t *rng, int32_t top);
/** Randomly return true according to <b>rng</b> with probability 1 in
 * <b>n</b> */
#define tor_weak_random_one_in_n(rng, n) (0==tor_weak_random_range((rng),(n)))

int format_hex_number_sigsafe(unsigned long x, char *buf, int max_len);
int format_dec_number_sigsafe(unsigned long x, char *buf, int max_len);

#ifdef UTIL_PRIVATE
/* Prototypes for private functions only used by util.c (and unit tests) */

#ifndef _WIN32
STATIC int format_helper_exit_status(unsigned char child_state,
                              int saved_errno, char *hex_errno);

/* Space for hex values of child state, a slash, saved_errno (with
   leading minus) and newline (no null) */
#define HEX_ERRNO_SIZE (sizeof(char) * 2 + 1 + \
                        1 + sizeof(int) * 2 + 1)
#endif

#endif

#define ARRAY_LENGTH(x) ((sizeof(x)) / sizeof(x[0]))

#endif