1 files changed, 326 insertions, 0 deletions

diff --git a/random/unix/apr_random.c b/random/unix/apr_random.c
new file mode 100644
index 0000000..9aee3e9
--- /dev/null
+++ b/random/unix/apr_random.c
@@ -0,0 +1,326 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ * See the paper "On Randomness" by Ben Laurie for an explanation of this PRNG.
+ * http://www.apache-ssl.org/randomness.pdf
+ * XXX: Is there a formal proof of this PRNG? Couldn't we use the more popular
+ * Mersenne Twister PRNG (and BSD licensed)?
+ */
+
+#include "apr.h"
+#include "apr_pools.h"
+#include "apr_random.h"
+#include "apr_thread_proc.h"
+#include <assert.h>
+
+#ifdef min
+#undef min
+#endif
+#define min(a,b) ((a) < (b) ? (a) : (b))
+
+#define APR_RANDOM_DEFAULT_POOLS 32
+#define APR_RANDOM_DEFAULT_REHASH_SIZE 1024
+#define APR_RANDOM_DEFAULT_RESEED_SIZE 32
+#define APR_RANDOM_DEFAULT_HASH_SECRET_SIZE 32
+#define APR_RANDOM_DEFAULT_G_FOR_INSECURE 32
+#define APR_RANDOM_DEFAULT_G_FOR_SECURE 320
+
+typedef struct apr_random_pool_t {
+    unsigned char *pool;
+    unsigned int bytes;
+    unsigned int pool_size;
+} apr_random_pool_t;
+
+#define hash_init(h)            (h)->init(h)
+#define hash_add(h,b,n)         (h)->add(h,b,n)
+#define hash_finish(h,r)        (h)->finish(h,r)
+
+#define hash(h,r,b,n)           hash_init(h),hash_add(h,b,n),hash_finish(h,r)
+
+#define crypt_setkey(c,k)       (c)->set_key((c)->data,k)
+#define crypt_crypt(c,out,in)   (c)->crypt((c)->date,out,in)
+
+struct apr_random_t {
+    apr_pool_t *apr_pool;
+    apr_crypto_hash_t *pool_hash;
+    unsigned int npools;
+    apr_random_pool_t *pools;
+    unsigned int next_pool;
+    unsigned int generation;
+    apr_size_t rehash_size;
+    apr_size_t reseed_size;
+    apr_crypto_hash_t *key_hash;
+#define K_size(g) ((g)->key_hash->size)
+    apr_crypto_hash_t *prng_hash;
+#define B_size(g) ((g)->prng_hash->size)
+
+    unsigned char *H;
+    unsigned char *H_waiting;
+#define H_size(g) (B_size(g)+K_size(g))
+#define H_current(g) (((g)->insecure_started && !(g)->secure_started) \
+                      ? (g)->H_waiting : (g)->H)
+
+    unsigned char *randomness;
+    apr_size_t random_bytes;
+    unsigned int g_for_insecure;
+    unsigned int g_for_secure;
+    unsigned int secure_base;
+    unsigned int insecure_started:1;
+    unsigned int secure_started:1;
+
+    apr_random_t *next;
+};
+
+static apr_random_t *all_random;
+
+static apr_status_t random_cleanup(void *data)
+{
+    apr_random_t *remove_this = data,
+                 *cur = all_random,
+                 **prev_ptr = &all_random;
+    while (cur) {
+        if (cur == remove_this) {
+            *prev_ptr = cur->next;
+            break;
+        }
+        prev_ptr = &cur->next;
+        cur = cur->next;
+    }
+    return APR_SUCCESS;
+}
+
+
+APR_DECLARE(void) apr_random_init(apr_random_t *g,apr_pool_t *p,
+                                  apr_crypto_hash_t *pool_hash,
+                                  apr_crypto_hash_t *key_hash,
+                                  apr_crypto_hash_t *prng_hash)
+{
+    unsigned int n;
+
+    g->apr_pool = p;
+
+    g->pool_hash = pool_hash;
+    g->key_hash = key_hash;
+    g->prng_hash = prng_hash;
+
+    g->npools = APR_RANDOM_DEFAULT_POOLS;
+    g->pools = apr_palloc(p,g->npools*sizeof *g->pools);
+    for (n = 0; n < g->npools; ++n) {
+        g->pools[n].bytes = g->pools[n].pool_size = 0;
+        g->pools[n].pool = NULL;
+    }
+    g->next_pool = 0;
+
+    g->generation = 0;
+
+    g->rehash_size = APR_RANDOM_DEFAULT_REHASH_SIZE;
+    /* Ensure that the rehash size is twice the size of the pool hasher */
+    g->rehash_size = ((g->rehash_size+2*g->pool_hash->size-1)/g->pool_hash->size
+                    /2)*g->pool_hash->size*2;
+    g->reseed_size = APR_RANDOM_DEFAULT_RESEED_SIZE;
+
+    g->H = apr_pcalloc(p,H_size(g));
+    g->H_waiting = apr_pcalloc(p,H_size(g));
+
+    g->randomness = apr_palloc(p,B_size(g));
+    g->random_bytes = 0;
+
+    g->g_for_insecure = APR_RANDOM_DEFAULT_G_FOR_INSECURE;
+    g->secure_base = 0;
+    g->g_for_secure = APR_RANDOM_DEFAULT_G_FOR_SECURE;
+    g->secure_started = g->insecure_started = 0;
+
+    g->next = all_random;
+    all_random = g;
+    apr_pool_cleanup_register(p, g, random_cleanup, apr_pool_cleanup_null);
+}
+
+static void mix_pid(apr_random_t *g,unsigned char *H,pid_t pid)
+{
+    hash_init(g->key_hash);
+    hash_add(g->key_hash,H,H_size(g));
+    hash_add(g->key_hash,&pid,sizeof pid);
+    hash_finish(g->key_hash,H);
+}
+
+static void mixer(apr_random_t *g,pid_t pid)
+{
+    unsigned char *H = H_current(g);
+
+    /* mix the PID into the current H */
+    mix_pid(g,H,pid);
+    /* if we are in waiting, then also mix into main H */
+    if (H != g->H)
+        mix_pid(g,g->H,pid);
+    /* change order of pool mixing for good measure - note that going
+       backwards is much better than going forwards */
+    --g->generation;
+    /* blow away any lingering randomness */
+    g->random_bytes = 0;
+}
+
+APR_DECLARE(void) apr_random_after_fork(apr_proc_t *proc)
+{
+    apr_random_t *r;
+
+    for (r = all_random; r; r = r->next)
+        /* 
+         * XXX Note: the pid does not provide sufficient entropy to 
+         * actually call this secure.  See Ben's paper referenced at 
+         * the top of this file. 
+         */
+        mixer(r,proc->pid);
+}
+
+APR_DECLARE(apr_random_t *) apr_random_standard_new(apr_pool_t *p)
+{
+    apr_random_t *r = apr_palloc(p,sizeof *r);
+    
+    apr_random_init(r,p,apr_crypto_sha256_new(p),apr_crypto_sha256_new(p),
+                    apr_crypto_sha256_new(p));
+    return r;
+}
+
+static void rekey(apr_random_t *g)
+{
+    unsigned int n;
+    unsigned char *H = H_current(g);
+
+    hash_init(g->key_hash);
+    hash_add(g->key_hash,H,H_size(g));
+    for (n = 0 ; n < g->npools && (n == 0 || g->generation&(1 << (n-1)))
+            ; ++n) {
+        hash_add(g->key_hash,g->pools[n].pool,g->pools[n].bytes);
+        g->pools[n].bytes = 0;
+    }
+    hash_finish(g->key_hash,H+B_size(g));
+
+    ++g->generation;
+    if (!g->insecure_started && g->generation > g->g_for_insecure) {
+        g->insecure_started = 1;
+        if (!g->secure_started) {
+            memcpy(g->H_waiting,g->H,H_size(g));
+            g->secure_base = g->generation;
+        }
+    }
+
+    if (!g->secure_started && g->generation > g->secure_base+g->g_for_secure) {
+        g->secure_started = 1;
+        memcpy(g->H,g->H_waiting,H_size(g));
+    }
+}
+
+APR_DECLARE(void) apr_random_add_entropy(apr_random_t *g,const void *entropy_,
+                                         apr_size_t bytes)
+{
+    unsigned int n;
+    const unsigned char *entropy = entropy_;
+
+    for (n = 0; n < bytes; ++n) {
+        apr_random_pool_t *p = &g->pools[g->next_pool];
+
+        if (++g->next_pool == g->npools)
+            g->next_pool = 0;
+
+        if (p->pool_size < p->bytes+1) {
+            unsigned char *np = apr_palloc(g->apr_pool,(p->bytes+1)*2);
+
+            if (p->pool) memcpy(np,p->pool,p->bytes);
+            p->pool = np;
+            p->pool_size = (p->bytes+1)*2;
+        }
+        p->pool[p->bytes++] = entropy[n];
+
+        if (p->bytes == g->rehash_size) {
+            apr_size_t r;
+
+            for (r = 0; r < p->bytes/2; r+=g->pool_hash->size)
+                hash(g->pool_hash,p->pool+r,p->pool+r*2,g->pool_hash->size*2);
+            p->bytes/=2;
+        }
+        assert(p->bytes < g->rehash_size);
+    }
+
+    if (g->pools[0].bytes >= g->reseed_size)
+        rekey(g);
+}
+
+/* This will give g->B_size bytes of randomness */
+static void apr_random_block(apr_random_t *g,unsigned char *random)
+{
+    /* FIXME: in principle, these are different hashes */
+    hash(g->prng_hash,g->H,g->H,H_size(g));
+    hash(g->prng_hash,random,g->H,B_size(g));
+}
+
+static void apr_random_bytes(apr_random_t *g,unsigned char *random,
+                             apr_size_t bytes)
+{
+    apr_size_t n;
+
+    for (n = 0; n < bytes; ) {
+        apr_size_t l;
+
+        if (g->random_bytes == 0) {
+            apr_random_block(g,g->randomness);
+            g->random_bytes = B_size(g);
+        }
+        l = min(bytes-n,g->random_bytes);
+        memcpy(&random[n],g->randomness+B_size(g)-g->random_bytes,l);
+        g->random_bytes-=l;
+        n+=l;
+    }
+}
+
+APR_DECLARE(apr_status_t) apr_random_secure_bytes(apr_random_t *g,
+                                                  void *random,
+                                                  apr_size_t bytes)
+{
+    if (!g->secure_started)
+        return APR_ENOTENOUGHENTROPY;
+    apr_random_bytes(g,random,bytes);
+    return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_status_t) apr_random_insecure_bytes(apr_random_t *g,
+                                                    void *random,
+                                                    apr_size_t bytes)
+{
+    if (!g->insecure_started)
+        return APR_ENOTENOUGHENTROPY;
+    apr_random_bytes(g,random,bytes);
+    return APR_SUCCESS;
+}
+
+APR_DECLARE(void) apr_random_barrier(apr_random_t *g)
+{
+    g->secure_started = 0;
+    g->secure_base = g->generation;
+}
+
+APR_DECLARE(apr_status_t) apr_random_secure_ready(apr_random_t *r)
+{
+    if (!r->secure_started)
+        return APR_ENOTENOUGHENTROPY;
+    return APR_SUCCESS;
+}
+
+APR_DECLARE(apr_status_t) apr_random_insecure_ready(apr_random_t *r)
+{
+    if (!r->insecure_started)
+        return APR_ENOTENOUGHENTROPY;
+    return APR_SUCCESS;
+}