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c-ares/backport-001-CVE-2023-31147.patch
xinghe 2f9abacd5f fix CVE-2023-31124 CVE-2023-31147
2023-06-01 01:08:14 +00:00

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From 823df3b989e59465d17b0a2eb1239a5fc048b4e5 Mon Sep 17 00:00:00 2001
From: Brad House <brad@brad-house.com>
Date: Mon, 22 May 2023 06:51:06 -0400
Subject: [PATCH] Merge pull request from GHSA-8r8p-23f3-64c2
* segment random number generation into own file
* abstract random code to make it more modular so we can have multiple backends
* rand: add support for arc4random_buf() and also direct CARES_RANDOM_FILE reading
* autotools: fix detection of arc4random_buf
* rework initial rc4 seed for PRNG as last fallback
* rc4: more proper implementation, simplified for clarity
* clarifications
Conflict:NA
Reference:https://github.com/c-ares/c-ares/commit/823df3b989e59465d17b0a2eb1239a5fc048b4e5
---
CMakeLists.txt | 2 +
configure.ac | 1 +
m4/cares-functions.m4 | 85 +++++++++++
src/lib/Makefile.inc | 1 +
src/lib/ares_config.h.cmake | 3 +
src/lib/ares_destroy.c | 3 +
src/lib/ares_init.c | 89 ++----------
src/lib/ares_private.h | 19 ++-
src/lib/ares_query.c | 36 +----
src/lib/ares_rand.c | 274 ++++++++++++++++++++++++++++++++++++
10 files changed, 387 insertions(+), 126 deletions(-)
create mode 100644 src/lib/ares_rand.c
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3987d0ab7..e2290af10 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -393,6 +393,8 @@ CHECK_SYMBOL_EXISTS (strncasecmp "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_STRNCAS
CHECK_SYMBOL_EXISTS (strncmpi "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_STRNCMPI)
CHECK_SYMBOL_EXISTS (strnicmp "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_STRNICMP)
CHECK_SYMBOL_EXISTS (writev "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_WRITEV)
+CHECK_SYMBOL_EXISTS (arc4random_buf "${CMAKE_EXTRA_INCLUDE_FILES}" HAVE_ARC4RANDOM_BUF)
+
# On Android, the system headers may define __system_property_get(), but excluded
# from libc. We need to perform a link test instead of a header/symbol test.
diff --git a/configure.ac b/configure.ac
index 7884cbb26..54e79d6e2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -683,6 +683,7 @@ CARES_CHECK_FUNC_STRNCASECMP
CARES_CHECK_FUNC_STRNCMPI
CARES_CHECK_FUNC_STRNICMP
CARES_CHECK_FUNC_WRITEV
+CARES_CHECK_FUNC_ARC4RANDOM_BUF
dnl check for AF_INET6
diff --git a/m4/cares-functions.m4 b/m4/cares-functions.m4
index 0f3992c7f..d4f4f994c 100644
--- a/m4/cares-functions.m4
+++ b/m4/cares-functions.m4
@@ -3753,3 +3753,88 @@ AC_DEFUN([CARES_CHECK_FUNC_WRITEV], [
ac_cv_func_writev="no"
fi
])
+
+dnl CARES_CHECK_FUNC_ARC4RANDOM_BUF
+dnl -------------------------------------------------
+dnl Verify if arc4random_buf is available, prototyped, and
+dnl can be compiled. If all of these are true, and
+dnl usage has not been previously disallowed with
+dnl shell variable cares_disallow_arc4random_buf, then
+dnl HAVE_ARC4RANDOM_BUF will be defined.
+
+AC_DEFUN([CARES_CHECK_FUNC_ARC4RANDOM_BUF], [
+ AC_REQUIRE([CARES_INCLUDES_STDLIB])dnl
+ #
+ tst_links_arc4random_buf="unknown"
+ tst_proto_arc4random_buf="unknown"
+ tst_compi_arc4random_buf="unknown"
+ tst_allow_arc4random_buf="unknown"
+ #
+ AC_MSG_CHECKING([if arc4random_buf can be linked])
+ AC_LINK_IFELSE([
+ AC_LANG_FUNC_LINK_TRY([arc4random_buf])
+ ],[
+ AC_MSG_RESULT([yes])
+ tst_links_arc4random_buf="yes"
+ ],[
+ AC_MSG_RESULT([no])
+ tst_links_arc4random_buf="no"
+ ])
+ #
+ if test "$tst_links_arc4random_buf" = "yes"; then
+ AC_MSG_CHECKING([if arc4random_buf is prototyped])
+ AC_EGREP_CPP([arc4random_buf],[
+ $cares_includes_stdlib
+ ],[
+ AC_MSG_RESULT([yes])
+ tst_proto_arc4random_buf="yes"
+ ],[
+ AC_MSG_RESULT([no])
+ tst_proto_arc4random_buf="no"
+ ])
+ fi
+ #
+ if test "$tst_proto_arc4random_buf" = "yes"; then
+ AC_MSG_CHECKING([if arc4random_buf is compilable])
+ AC_COMPILE_IFELSE([
+ AC_LANG_PROGRAM([[
+ $cares_includes_stdlib
+ ]],[[
+ arc4random_buf(NULL, 0);
+ return 1;
+ ]])
+ ],[
+ AC_MSG_RESULT([yes])
+ tst_compi_arc4random_buf="yes"
+ ],[
+ AC_MSG_RESULT([no])
+ tst_compi_arc4random_buf="no"
+ ])
+ fi
+ #
+ if test "$tst_compi_arc4random_buf" = "yes"; then
+ AC_MSG_CHECKING([if arc4random_buf usage allowed])
+ if test "x$cares_disallow_arc4random_buf" != "xyes"; then
+ AC_MSG_RESULT([yes])
+ tst_allow_arc4random_buf="yes"
+ else
+ AC_MSG_RESULT([no])
+ tst_allow_arc4random_buf="no"
+ fi
+ fi
+ #
+ AC_MSG_CHECKING([if arc4random_buf might be used])
+ if test "$tst_links_arc4random_buf" = "yes" &&
+ test "$tst_proto_arc4random_buf" = "yes" &&
+ test "$tst_compi_arc4random_buf" = "yes" &&
+ test "$tst_allow_arc4random_buf" = "yes"; then
+ AC_MSG_RESULT([yes])
+ AC_DEFINE_UNQUOTED(HAVE_ARC4RANDOM_BUF, 1,
+ [Define to 1 if you have the arc4random_buf function.])
+ ac_cv_func_arc4random_buf="yes"
+ else
+ AC_MSG_RESULT([no])
+ ac_cv_func_arc4random_buf="no"
+ fi
+])
+
diff --git a/src/lib/Makefile.inc b/src/lib/Makefile.inc
index 140378d67..49bbe6016 100644
--- a/src/lib/Makefile.inc
+++ b/src/lib/Makefile.inc
@@ -45,6 +45,7 @@ CSOURCES = ares__addrinfo2hostent.c \
ares_platform.c \
ares_process.c \
ares_query.c \
+ ares_rand.c \
ares_search.c \
ares_send.c \
ares_strcasecmp.c \
diff --git a/src/lib/ares_config.h.cmake b/src/lib/ares_config.h.cmake
index fddb78535..798820a3a 100644
--- a/src/lib/ares_config.h.cmake
+++ b/src/lib/ares_config.h.cmake
@@ -346,6 +346,9 @@
/* Define to 1 if you need the memory.h header file even with stdlib.h */
#cmakedefine NEED_MEMORY_H
+/* Define if have arc4random_buf() */
+#cmakedefine HAVE_ARC4RANDOM_BUF
+
/* a suitable file/device to read random data from */
#cmakedefine CARES_RANDOM_FILE "@CARES_RANDOM_FILE@"
diff --git a/src/lib/ares_destroy.c b/src/lib/ares_destroy.c
index 7ec2bde5a..62c899f82 100644
--- a/src/lib/ares_destroy.c
+++ b/src/lib/ares_destroy.c
@@ -95,6 +95,9 @@ void ares_destroy(ares_channel channel)
if (channel->resolvconf_path)
ares_free(channel->resolvconf_path);
+ if (channel->rand_state)
+ ares__destroy_rand_state(channel->rand_state);
+
ares_free(channel);
}
diff --git a/src/lib/ares_init.c b/src/lib/ares_init.c
index c7ca7af1b..0519f43e5 100644
--- a/src/lib/ares_init.c
+++ b/src/lib/ares_init.c
@@ -87,7 +76,6 @@ static int config_nameserver(struct server_state **servers, int *nservers,
static int set_search(ares_channel channel, const char *str);
static int set_options(ares_channel channel, const char *str);
static const char *try_option(const char *p, const char *q, const char *opt);
-static int init_id_key(rc4_key* key,int key_data_len);
static int config_sortlist(struct apattern **sortlist, int *nsort,
const char *str);
@@ -165,6 +153,7 @@ int ares_init_options(ares_channel *channelptr, struct ares_options *options,
channel->sock_funcs = NULL;
channel->sock_func_cb_data = NULL;
channel->resolvconf_path = NULL;
+ channel->rand_state = NULL;
channel->last_server = 0;
channel->last_timeout_processed = (time_t)now.tv_sec;
@@ -218,9 +207,13 @@ int ares_init_options(ares_channel *channelptr, struct ares_options *options,
/* Generate random key */
if (status == ARES_SUCCESS) {
- status = init_id_key(&channel->id_key, ARES_ID_KEY_LEN);
+ channel->rand_state = ares__init_rand_state();
+ if (channel->rand_state == NULL) {
+ status = ARES_ENOMEM;
+ }
+
if (status == ARES_SUCCESS)
- channel->next_id = ares__generate_new_id(&channel->id_key);
+ channel->next_id = ares__generate_new_id(channel->rand_state);
else
DEBUGF(fprintf(stderr, "Error: init_id_key failed: %s\n",
ares_strerror(status)));
@@ -242,6 +235,8 @@ int ares_init_options(ares_channel *channelptr, struct ares_options *options,
ares_free(channel->lookups);
if(channel->resolvconf_path)
ares_free(channel->resolvconf_path);
+ if (channel->rand_state)
+ ares__destroy_rand_state(channel->rand_state);
ares_free(channel);
return status;
}
@@ -2182,76 +2177,6 @@ static int sortlist_alloc(struct apattern **sortlist, int *nsort,
return 1;
}
-/* initialize an rc4 key. If possible a cryptographically secure random key
- is generated using a suitable function (for example win32's RtlGenRandom as
- described in
- http://blogs.msdn.com/michael_howard/archive/2005/01/14/353379.aspx
- otherwise the code defaults to cross-platform albeit less secure mechanism
- using rand
-*/
-static void randomize_key(unsigned char* key,int key_data_len)
-{
- int randomized = 0;
- int counter=0;
-#ifdef WIN32
- BOOLEAN res;
- if (ares_fpSystemFunction036)
- {
- res = (*ares_fpSystemFunction036) (key, key_data_len);
- if (res)
- randomized = 1;
- }
-#else /* !WIN32 */
-#ifdef CARES_RANDOM_FILE
- FILE *f = fopen(CARES_RANDOM_FILE, "rb");
- if(f) {
- setvbuf(f, NULL, _IONBF, 0);
- counter = aresx_uztosi(fread(key, 1, key_data_len, f));
- fclose(f);
- }
-#endif
-#endif /* WIN32 */
-
- if (!randomized) {
- for (;counter<key_data_len;counter++)
- key[counter]=(unsigned char)(rand() % 256); /* LCOV_EXCL_LINE */
- }
-}
-
-static int init_id_key(rc4_key* key,int key_data_len)
-{
- unsigned char index1;
- unsigned char index2;
- unsigned char* state;
- short counter;
- unsigned char *key_data_ptr = 0;
-
- key_data_ptr = ares_malloc(key_data_len);
- if (!key_data_ptr)
- return ARES_ENOMEM;
- memset(key_data_ptr, 0, key_data_len);
-
- state = &key->state[0];
- for(counter = 0; counter < 256; counter++)
- /* unnecessary AND but it keeps some compilers happier */
- state[counter] = (unsigned char)(counter & 0xff);
- randomize_key(key->state,key_data_len);
- key->x = 0;
- key->y = 0;
- index1 = 0;
- index2 = 0;
- for(counter = 0; counter < 256; counter++)
- {
- index2 = (unsigned char)((key_data_ptr[index1] + state[counter] +
- index2) % 256);
- ARES_SWAP_BYTE(&state[counter], &state[index2]);
-
- index1 = (unsigned char)((index1 + 1) % key_data_len);
- }
- ares_free(key_data_ptr);
- return ARES_SUCCESS;
-}
-
void ares_set_local_ip4(ares_channel channel, unsigned int local_ip)
{
channel->local_ip4 = local_ip;
diff --git a/src/lib/ares_private.h b/src/lib/ares_private.h
index 53043a651..b6eab8a7d 100644
--- a/src/lib/ares_private.h
+++ b/src/lib/ares_private.h
@@ -101,8 +101,6 @@ W32_FUNC const char *_w32_GetHostsFile (void);
#endif
-#define ARES_ID_KEY_LEN 31
-
#include "ares_ipv6.h"
#include "ares_llist.h"
@@ -262,12 +260,8 @@ struct apattern {
unsigned short type;
};
-typedef struct rc4_key
-{
- unsigned char state[256];
- unsigned char x;
- unsigned char y;
-} rc4_key;
+struct ares_rand_state;
+typedef struct ares_rand_state ares_rand_state;
struct ares_channeldata {
/* Configuration data */
@@ -302,8 +296,8 @@ struct ares_channeldata {
/* ID to use for next query */
unsigned short next_id;
- /* key to use when generating new ids */
- rc4_key id_key;
+ /* random state to use when generating new ids */
+ ares_rand_state *rand_state;
/* Generation number to use for the next TCP socket open/close */
int tcp_connection_generation;
@@ -362,7 +356,10 @@ void ares__close_sockets(ares_channel channel, struct server_state *server);
int ares__get_hostent(FILE *fp, int family, struct hostent **host);
int ares__read_line(FILE *fp, char **buf, size_t *bufsize);
void ares__free_query(struct query *query);
-unsigned short ares__generate_new_id(rc4_key* key);
+
+ares_rand_state *ares__init_rand_state(void);
+void ares__destroy_rand_state(ares_rand_state *state);
+unsigned short ares__generate_new_id(ares_rand_state *state);
struct timeval ares__tvnow(void);
int ares__expand_name_validated(const unsigned char *encoded,
const unsigned char *abuf,
diff --git a/src/lib/ares_query.c b/src/lib/ares_query.c
index 508274db3..42323bec5 100644
--- a/src/lib/ares_query.c
+++ b/src/lib/ares_query.c
@@ -33,32 +33,6 @@ struct qquery {
static void qcallback(void *arg, int status, int timeouts, unsigned char *abuf, int alen);
-static void rc4(rc4_key* key, unsigned char *buffer_ptr, int buffer_len)
-{
- unsigned char x;
- unsigned char y;
- unsigned char* state;
- unsigned char xorIndex;
- int counter;
-
- x = key->x;
- y = key->y;
-
- state = &key->state[0];
- for(counter = 0; counter < buffer_len; counter ++)
- {
- x = (unsigned char)((x + 1) % 256);
- y = (unsigned char)((state[x] + y) % 256);
- ARES_SWAP_BYTE(&state[x], &state[y]);
-
- xorIndex = (unsigned char)((state[x] + state[y]) % 256);
-
- buffer_ptr[counter] = (unsigned char)(buffer_ptr[counter]^state[xorIndex]);
- }
- key->x = x;
- key->y = y;
-}
-
static struct query* find_query_by_id(ares_channel channel, unsigned short id)
{
unsigned short qid;
@@ -78,7 +52,6 @@ static struct query* find_query_by_id(ares_channel channel, unsigned short id)
return NULL;
}
-
/* a unique query id is generated using an rc4 key. Since the id may already
be used by a running query (as infrequent as it may be), a lookup is
performed per id generation. In practice this search should happen only
@@ -89,19 +62,12 @@ static unsigned short generate_unique_id(ares_channel channel)
unsigned short id;
do {
- id = ares__generate_new_id(&channel->id_key);
+ id = ares__generate_new_id(channel->rand_state);
} while (find_query_by_id(channel, id));
return (unsigned short)id;
}
-unsigned short ares__generate_new_id(rc4_key* key)
-{
- unsigned short r=0;
- rc4(key, (unsigned char *)&r, sizeof(r));
- return r;
-}
-
void ares_query(ares_channel channel, const char *name, int dnsclass,
int type, ares_callback callback, void *arg)
{
diff --git a/src/lib/ares_rand.c b/src/lib/ares_rand.c
new file mode 100644
index 000000000..a564bc236
--- /dev/null
+++ b/src/lib/ares_rand.c
@@ -0,0 +1,274 @@
+/* Copyright 1998 by the Massachusetts Institute of Technology.
+ * Copyright (C) 2007-2013 by Daniel Stenberg
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software and its documentation for any purpose and without
+ * fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose. It is provided "as is"
+ * without express or implied warranty.
+ */
+
+#include "ares_setup.h"
+#include "ares.h"
+#include "ares_private.h"
+#include "ares_nowarn.h"
+#include <stdlib.h>
+
+typedef enum {
+ ARES_RAND_OS = 1, /* OS-provided such as RtlGenRandom or arc4random */
+ ARES_RAND_FILE = 2, /* OS file-backed random number generator */
+ ARES_RAND_RC4 = 3 /* Internal RC4 based PRNG */
+} ares_rand_backend;
+
+typedef struct ares_rand_rc4
+{
+ unsigned char S[256];
+ size_t i;
+ size_t j;
+} ares_rand_rc4;
+
+struct ares_rand_state
+{
+ ares_rand_backend type;
+ union {
+ FILE *rand_file;
+ ares_rand_rc4 rc4;
+ } state;
+};
+
+
+/* Define RtlGenRandom = SystemFunction036. This is in advapi32.dll. There is
+ * no need to dynamically load this, other software used widely does not.
+ * http://blogs.msdn.com/michael_howard/archive/2005/01/14/353379.aspx
+ * https://docs.microsoft.com/en-us/windows/win32/api/ntsecapi/nf-ntsecapi-rtlgenrandom
+ */
+#ifdef _WIN32
+BOOLEAN WINAPI SystemFunction036(PVOID RandomBuffer, ULONG RandomBufferLength);
+# ifndef RtlGenRandom
+# define RtlGenRandom(a,b) SystemFunction036(a,b)
+# endif
+#endif
+
+
+#define ARES_RC4_KEY_LEN 32 /* 256 bits */
+
+static unsigned int ares_u32_from_ptr(void *addr)
+{
+ if (sizeof(void *) == 8) {
+ return (unsigned int)((((size_t)addr >> 32) & 0xFFFFFFFF) | ((size_t)addr & 0xFFFFFFFF));
+ }
+ return (unsigned int)((size_t)addr & 0xFFFFFFFF);
+}
+
+
+/* initialize an rc4 key as the last possible fallback. */
+static void ares_rc4_generate_key(ares_rand_rc4 *rc4_state, unsigned char *key, size_t key_len)
+{
+ size_t i;
+ size_t len = 0;
+ unsigned int data;
+ struct timeval tv;
+
+ if (key_len != ARES_RC4_KEY_LEN)
+ return;
+
+ /* Randomness is hard to come by. Maybe the system randomizes heap and stack addresses.
+ * Maybe the current timestamp give us some randomness.
+ * Use rc4_state (heap), &i (stack), and ares__tvnow()
+ */
+ data = ares_u32_from_ptr(rc4_state);
+ memcpy(key + len, &data, sizeof(data));
+ len += sizeof(data);
+
+ data = ares_u32_from_ptr(&i);
+ memcpy(key + len, &data, sizeof(data));
+ len += sizeof(data);
+
+ tv = ares__tvnow();
+ data = (unsigned int)((tv.tv_sec | tv.tv_usec) & 0xFFFFFFFF);
+ memcpy(key + len, &data, sizeof(data));
+ len += sizeof(data);
+
+ srand(ares_u32_from_ptr(rc4_state) | ares_u32_from_ptr(&i) | (unsigned int)((tv.tv_sec | tv.tv_usec) & 0xFFFFFFFF));
+
+ for (i=len; i<key_len; i++) {
+ key[i]=(unsigned char)(rand() % 256); /* LCOV_EXCL_LINE */
+ }
+}
+
+
+static void ares_rc4_init(ares_rand_rc4 *rc4_state)
+{
+ unsigned char key[ARES_RC4_KEY_LEN];
+ size_t i;
+ size_t j;
+
+ ares_rc4_generate_key(rc4_state, key, sizeof(key));
+
+ for (i = 0; i < sizeof(rc4_state->S); i++) {
+ rc4_state->S[i] = i & 0xFF;
+ }
+
+ for(i = 0, j = 0; i < 256; i++) {
+ j = (j + rc4_state->S[i] + key[i % sizeof(key)]) % 256;
+ ARES_SWAP_BYTE(&rc4_state->S[i], &rc4_state->S[j]);
+ }
+
+ rc4_state->i = 0;
+ rc4_state->j = 0;
+}
+
+/* Just outputs the key schedule, no need to XOR with any data since we have none */
+static void ares_rc4_prng(ares_rand_rc4 *rc4_state, unsigned char *buf, int len)
+{
+ unsigned char *S = rc4_state->S;
+ size_t i = rc4_state->i;
+ size_t j = rc4_state->j;
+ size_t cnt;
+
+ for (cnt=0; cnt<len; cnt++) {
+ i = (i + 1) % 256;
+ j = (j + S[i]) % 256;
+
+ ARES_SWAP_BYTE(&S[i], &S[j]);
+ buf[cnt] = S[(S[i] + S[j]) % 256];
+ }
+
+ rc4_state->i = i;
+ rc4_state->j = j;
+}
+
+
+static int ares__init_rand_engine(ares_rand_state *state)
+{
+ memset(state, 0, sizeof(*state));
+
+#if defined(HAVE_ARC4RANDOM_BUF) || defined(_WIN32)
+ state->type = ARES_RAND_OS;
+ return 1;
+#elif defined(CARES_RANDOM_FILE)
+ state->type = ARES_RAND_FILE;
+ state->state.rand_file = fopen(CARES_RANDOM_FILE, "rb");
+ if (state->state.rand_file) {
+ setvbuf(state->state.rand_file, NULL, _IONBF, 0);
+ return 1;
+ }
+ /* Fall-Thru on failure to RC4 */
+#endif
+
+ state->type = ARES_RAND_RC4;
+ ares_rc4_init(&state->state.rc4);
+
+ /* Currently cannot fail */
+ return 1;
+}
+
+
+ares_rand_state *ares__init_rand_state()
+{
+ ares_rand_state *state = NULL;
+
+ state = ares_malloc(sizeof(*state));
+ if (!state)
+ return NULL;
+
+ if (!ares__init_rand_engine(state)) {
+ ares_free(state);
+ return NULL;
+ }
+
+ return state;
+}
+
+
+static void ares__clear_rand_state(ares_rand_state *state)
+{
+ if (!state)
+ return;
+
+ switch (state->type) {
+ case ARES_RAND_OS:
+ break;
+ case ARES_RAND_FILE:
+ fclose(state->state.rand_file);
+ break;
+ case ARES_RAND_RC4:
+ break;
+ }
+}
+
+
+static void ares__reinit_rand(ares_rand_state *state)
+{
+ ares__clear_rand_state(state);
+ ares__init_rand_engine(state);
+}
+
+
+void ares__destroy_rand_state(ares_rand_state *state)
+{
+ if (!state)
+ return;
+
+ ares__clear_rand_state(state);
+ ares_free(state);
+}
+
+
+static void ares__rand_bytes(ares_rand_state *state, unsigned char *buf, size_t len)
+{
+
+ while (1) {
+ size_t rv;
+ size_t bytes_read = 0;
+
+ switch (state->type) {
+ case ARES_RAND_OS:
+#ifdef _WIN32
+ RtlGenRandom(buf, len);
+ return;
+#elif defined(HAVE_ARC4RANDOM_BUF)
+ arc4random_buf(buf, len);
+ return;
+#else
+ /* Shouldn't be possible to be here */
+ break;
+#endif
+
+ case ARES_RAND_FILE:
+ while (1) {
+ size_t rv = fread(buf + bytes_read, 1, len - bytes_read, state->state.rand_file);
+ if (rv == 0)
+ break; /* critical error, will reinit rand state */
+
+ bytes_read += rv;
+ if (bytes_read == len)
+ return;
+ }
+ break;
+
+ case ARES_RAND_RC4:
+ ares_rc4_prng(&state->state.rc4, buf, len);
+ return;
+ }
+
+ /* If we didn't return before we got here, that means we had a critical rand
+ * failure and need to reinitialized */
+ ares__reinit_rand(state);
+ }
+}
+
+unsigned short ares__generate_new_id(ares_rand_state *state)
+{
+ unsigned short r=0;
+
+ ares__rand_bytes(state, (unsigned char *)&r, sizeof(r));
+ return r;
+}
+
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