Curl_rand: fixed and moved to rand.c

Now Curl_rand() is made to fail if it cannot get the necessary random
level.

Changed the proto of Curl_rand() slightly to provide a number of ints at
once.

Moved out from vtls, since it isn't a TLS function and vtls provides
Curl_ssl_random() for this to use.

Discussion: https://curl.haxx.se/mail/lib-2016-11/0119.html

3 files changed, 14 insertions, 83 deletions

diff --git a/lib/vtls/gskit.h b/lib/vtls/gskit.h
index 41483cba6..e258a29f1 100644
--- a/lib/vtls/gskit.h
+++ b/lib/vtls/gskit.h
@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -64,7 +64,7 @@ int Curl_gskit_check_cxn(struct connectdata *cxn);
 #define curlssl_version Curl_gskit_version
 #define curlssl_check_cxn(x) Curl_gskit_check_cxn(x)
 #define curlssl_data_pending(x,y) 0
-#define curlssl_random(x,y,z) -1
+#define curlssl_random(x,y,z) (x=x, y=y, z=z, CURLE_NOT_BUILT_IN)
 
 #endif /* USE_GSKIT */
 
diff --git a/lib/vtls/vtls.c b/lib/vtls/vtls.c
index 56a882341..ed65b46b9 100644
--- a/lib/vtls/vtls.c
+++ b/lib/vtls/vtls.c
@@ -177,77 +177,6 @@ void Curl_free_ssl_config(struct ssl_config_data* sslc)
   Curl_safefree(sslc->clientcert);
 }
 
-
-/*
- * Curl_rand() returns a random unsigned integer, 32bit.
- *
- * This non-SSL function is put here only because this file is the only one
- * with knowledge of what the underlying SSL libraries provide in terms of
- * randomizers.
- *
- * NOTE: 'data' may be passed in as NULL when coming from external API without
- * easy handle!
- *
- */
-
-unsigned int Curl_rand(struct Curl_easy *data)
-{
-  unsigned int r = 0;
-  static unsigned int randseed;
-  static bool seeded = FALSE;
-
-#ifdef CURLDEBUG
-  char *force_entropy = getenv("CURL_ENTROPY");
-  if(force_entropy) {
-    if(!seeded) {
-      size_t elen = strlen(force_entropy);
-      size_t clen = sizeof(randseed);
-      size_t min = elen < clen ? elen : clen;
-      memcpy((char *)&randseed, force_entropy, min);
-      seeded = TRUE;
-    }
-    else
-      randseed++;
-    return randseed;
-  }
-#endif
-
-  /* data may be NULL! */
-  if(!Curl_ssl_random(data, (unsigned char *)&r, sizeof(r)))
-    return r;
-
-  /* If Curl_ssl_random() returns non-zero it couldn't offer randomness and we
-     instead perform a "best effort" */
-
-#ifdef RANDOM_FILE
-  if(!seeded) {
-    /* if there's a random file to read a seed from, use it */
-    int fd = open(RANDOM_FILE, O_RDONLY);
-    if(fd > -1) {
-      /* read random data into the randseed variable */
-      ssize_t nread = read(fd, &randseed, sizeof(randseed));
-      if(nread == sizeof(randseed))
-        seeded = TRUE;
-      close(fd);
-    }
-  }
-#endif
-
-  if(!seeded) {
-    struct timeval now = curlx_tvnow();
-    infof(data, "WARNING: Using weak random seed\n");
-    randseed += (unsigned int)now.tv_usec + (unsigned int)now.tv_sec;
-    randseed = randseed * 1103515245 + 12345;
-    randseed = randseed * 1103515245 + 12345;
-    randseed = randseed * 1103515245 + 12345;
-    seeded = TRUE;
-  }
-
-  /* Return an unsigned 32-bit pseudo-random number. */
-  r = randseed = randseed * 1103515245 + 12345;
-  return (r << 16) | ((r >> 16) & 0xFFFF);
-}
-
 int Curl_ssl_backend(void)
 {
   return (int)CURL_SSL_BACKEND;
@@ -736,11 +665,16 @@ CURLcode Curl_ssl_push_certinfo(struct Curl_easy *data,
   return Curl_ssl_push_certinfo_len(data, certnum, label, value, valuelen);
 }
 
-int Curl_ssl_random(struct Curl_easy *data,
-                     unsigned char *entropy,
-                     size_t length)
+CURLcode Curl_ssl_random(struct Curl_easy *data,
+                         unsigned char *entropy,
+                         size_t length)
 {
-  return curlssl_random(data, entropy, length);
+  int rc = curlssl_random(data, entropy, length);
+  if(rc) {
+    failf(data, "PRNG seeding failed");
+    return CURLE_FAILED_INIT; /* possibly weird return code */
+  }
+  return CURLE_OK;
 }
 
 /*
diff --git a/lib/vtls/vtls.h b/lib/vtls/vtls.h
index a41ecc325..69d206f52 100644
--- a/lib/vtls/vtls.h
+++ b/lib/vtls/vtls.h
@@ -56,8 +56,6 @@ bool Curl_clone_ssl_config(struct ssl_config_data* source,
                            struct ssl_config_data* dest);
 void Curl_free_ssl_config(struct ssl_config_data* sslc);
 
-unsigned int Curl_rand(struct Curl_easy *);
-
 int Curl_ssl_backend(void);
 
 #ifdef USE_SSL
@@ -140,10 +138,9 @@ void Curl_ssl_kill_session(struct curl_ssl_session *session);
  */
 void Curl_ssl_delsessionid(struct connectdata *conn, void *ssl_sessionid);
 
-/* get N random bytes into the buffer, return 0 if a find random is filled
-   in */
-int Curl_ssl_random(struct Curl_easy *data, unsigned char *buffer,
-                    size_t length);
+/* get N random bytes into the buffer */
+CURLcode Curl_ssl_random(struct Curl_easy *data, unsigned char *buffer,
+                         size_t length);
 CURLcode Curl_ssl_md5sum(unsigned char *tmp, /* input */
                          size_t tmplen,
                          unsigned char *md5sum, /* output */