Tor  0.4.3.1-alpha-dev
namemap.c
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1 /* Copyright (c) 2003-2004, Roger Dingledine
2  * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
3  * Copyright (c) 2007-2020, The Tor Project, Inc. */
4 /* See LICENSE for licensing information */
5 
6 /**
7  * @file namemap.c
8  * @brief Mappings between identifiers and 16-bit ints.
9  **/
10 
11 #include "orconfig.h"
13 #include "lib/container/namemap.h"
15 #include "lib/log/util_bug.h"
16 #include "lib/malloc/malloc.h"
17 #include "lib/string/printf.h"
18 
19 #include "ext/siphash.h"
20 
21 #include <string.h>
22 
23 /** Helper for namemap hashtable implementation: compare two entries. */
24 static inline int
26 {
27  return !strcmp(a->name, b->name);
28 }
29 
30 /** Helper for namemap hashtable implementation: hash an entry. */
31 static inline unsigned
33 {
34  return (unsigned) siphash24g(a->name, strlen(a->name));
35 }
36 
41 
42 /** Set up an uninitialized <b>map</b>. */
43 void
44 namemap_init(namemap_t *map)
45 {
46  memset(map, 0, sizeof(*map));
47  HT_INIT(namemap_ht, &map->ht);
48  map->names = smartlist_new();
49 }
50 
51 /** Return the name that <b>map</b> associates with a given <b>id</b>, or
52  * NULL if there is no such name. */
53 const char *
54 namemap_get_name(const namemap_t *map, unsigned id)
55 {
56  if (map->names && id < (unsigned)smartlist_len(map->names)) {
57  mapped_name_t *name = smartlist_get(map->names, (int)id);
58  return name->name;
59  } else {
60  return NULL;
61  }
62 }
63 
64 /**
65  * Return the name that <b>map</b> associates with a given <b>id</b>, or a
66  * pointer to a statically allocated string describing the value of <b>id</b>
67  * if no such name exists.
68  **/
69 const char *
70 namemap_fmt_name(const namemap_t *map, unsigned id)
71 {
72  static char buf[32];
73 
74  const char *name = namemap_get_name(map, id);
75  if (name)
76  return name;
77 
78  tor_snprintf(buf, sizeof(buf), "{%u}", id);
79 
80  return buf;
81 }
82 
83 /**
84  * Helper: As namemap_get_id(), but requires that <b>name</b> is
85  * <b>namelen</b> charaters long, and that <b>namelen</b> is no more than
86  * MAX_NAMEMAP_NAME_LEN.
87  */
88 static unsigned
90  const char *name,
91  size_t namelen)
92 {
93  union {
94  mapped_name_t n;
95  char storage[MAX_NAMEMAP_NAME_LEN + sizeof(mapped_name_t) + 1];
96  } u;
97  memcpy(u.n.name, name, namelen);
98  u.n.name[namelen] = 0;
99  const mapped_name_t *found = HT_FIND(namemap_ht, &map->ht, &u.n);
100  if (found) {
101  tor_assert(map->names);
102  tor_assert(smartlist_get(map->names, found->intval) == found);
103  return found->intval;
104  }
105 
106  return NAMEMAP_ERR;
107 }
108 
109 /**
110  * Return the identifier currently associated by <b>map</b> with the name
111  * <b>name</b>, or NAMEMAP_ERR if no such identifier exists.
112  **/
113 unsigned
115  const char *name)
116 {
117  size_t namelen = strlen(name);
118  if (namelen > MAX_NAMEMAP_NAME_LEN) {
119  return NAMEMAP_ERR;
120  }
121 
122  return namemap_get_id_unchecked(map, name, namelen);
123 }
124 
125 /**
126  * Return the identifier associated by <b>map</b> with the name
127  * <b>name</b>, allocating a new identifier in <b>map</b> if none exists.
128  *
129  * Return NAMEMAP_ERR if <b>name</b> is too long, or if there are no more
130  * identifiers we can allocate.
131  **/
132 unsigned
134  const char *name)
135 {
136  size_t namelen = strlen(name);
137  if (namelen > MAX_NAMEMAP_NAME_LEN) {
138  return NAMEMAP_ERR;
139  }
140 
141  if (PREDICT_UNLIKELY(map->names == NULL))
142  map->names = smartlist_new();
143 
144  unsigned found = namemap_get_id_unchecked(map, name, namelen);
145  if (found != NAMEMAP_ERR)
146  return found;
147 
148  unsigned new_id = (unsigned)smartlist_len(map->names);
149  if (new_id == NAMEMAP_ERR)
150  return NAMEMAP_ERR; /* Can't allocate any more. */
151 
152  mapped_name_t *insert = tor_malloc_zero(
153  offsetof(mapped_name_t, name) + namelen + 1);
154  memcpy(insert->name, name, namelen+1);
155  insert->intval = new_id;
156 
157  HT_INSERT(namemap_ht, &map->ht, insert);
158  smartlist_add(map->names, insert);
159 
160  return new_id;
161 }
162 
163 /** Return the number of entries in 'names' */
164 size_t
166 {
167  if (PREDICT_UNLIKELY(map->names == NULL))
168  return 0;
169 
170  return smartlist_len(map->names);
171 }
172 
173 /**
174  * Release all storage held in <b>map</b>.
175  */
176 void
178 {
179  if (!map)
180  return;
181 
182  HT_CLEAR(namemap_ht, &map->ht);
183  if (map->names) {
184  SMARTLIST_FOREACH(map->names, mapped_name_t *, n,
185  tor_free(n));
186  smartlist_free(map->names);
187  }
188  memset(map, 0, sizeof(*map));
189 }
const char * namemap_get_name(const namemap_t *map, unsigned id)
Definition: namemap.c:54
#define MAX_NAMEMAP_NAME_LEN
Definition: namemap_st.h:20
Header for printf.c.
Header for smartlist.c.
Internal declarations for namemap structure.
unsigned namemap_get_id(const namemap_t *map, const char *name)
Definition: namemap.c:114
void smartlist_add(smartlist_t *sl, void *element)
Header for namemap.c.
#define tor_assert(expr)
Definition: util_bug.h:102
static unsigned mapped_name_hash(const mapped_name_t *a)
Definition: namemap.c:32
#define tor_free(p)
Definition: malloc.h:52
const char * name
Definition: config.c:2441
Headers for util_malloc.c.
size_t namemap_get_size(const namemap_t *map)
Definition: namemap.c:165
smartlist_t * smartlist_new(void)
void * tor_reallocarray_(void *ptr, size_t sz1, size_t sz2)
Definition: malloc.c:146
static unsigned namemap_get_id_unchecked(const namemap_t *map, const char *name, size_t namelen)
Definition: namemap.c:89
HT_PROTOTYPE(HT_GENERATE2(namemap_ht, HT_GENERATE2(mapped_name_t, HT_GENERATE2(node, HT_GENERATE2(mapped_name_hash, HT_GENERATE2(mapped_name_eq)
Definition: namemap.c:37
unsigned namemap_get_or_create_id(namemap_t *map, const char *name)
Definition: namemap.c:133
HT_GENERATE2(cdm_diff_ht, cdm_diff_t, node, cdm_diff_hash, cdm_diff_eq, 0.6, tor_reallocarray, tor_free_) static void cdm_diff_free_(cdm_diff_t *diff)
Definition: consdiffmgr.c:222
void tor_free_(void *mem)
Definition: malloc.c:227
void namemap_clear(namemap_t *map)
Definition: namemap.c:177
const char * namemap_fmt_name(const namemap_t *map, unsigned id)
Definition: namemap.c:70
int tor_snprintf(char *str, size_t size, const char *format,...)
Definition: printf.c:27
static int mapped_name_eq(const mapped_name_t *a, const mapped_name_t *b)
Definition: namemap.c:25
#define SMARTLIST_FOREACH(sl, type, var, cmd)
#define NAMEMAP_ERR
Definition: namemap.h:23
Macros to manage assertions, fatal and non-fatal.