commit d79156fbbb498ddb8d227d1e018ea7820b2e81d8
author Scott Graham <scottmg@google.com> Mon Jan 14 16:52:14 2019 -0800
committer Scott Graham <scottmg@google.com> Mon Jan 14 16:53:59 2019 -0800
tree 88d5fbe2b0eec78910721067220b74b2c67aba04
parent 60a3d5ab0fbffb177b37e9a47dec57aba1de11ea

[libc] Avoid use of random() in third_party/iperf

random() is implemented as i++. Instead, call zx_cprng_draw() to get
randomness, as it would be nice to remove random() from libc.

ZX-3307 #comment [libc] Avoid use of random() in third_party/iperf

Test: CQ
Change-Id: I066f0eca90d61e0900ac8c7e2495cb448918aac6

src/iperf_api.c

diff --git a/src/iperf_api.c b/src/iperf_api.c
index a3fe299..635e71c 100755
--- a/src/iperf_api.c
+++ b/src/iperf_api.c
@@ -63,6 +63,8 @@
 #include <sys/cpuset.h>
 #endif /* HAVE_CPUSET_SETAFFINITY */
 
+#include <zircon/syscalls.h>
+
 #include "net.h"
 #include "iperf.h"
 #include "iperf_api.h"
@@ -2798,9 +2800,7 @@
         free(sp);
         return NULL;
     }
-    srandom(time(NULL));
-    for (i = 0; i < test->settings->blksize; ++i)
-        sp->buffer[i] = random();
+    zx_cprng_draw(sp->buffer, test->settings->blksize);
 
     /* Set socket */
     sp->socket = s;

src/iperf_util.c

diff --git a/src/iperf_util.c b/src/iperf_util.c
index f185115..b493ff7 100644
--- a/src/iperf_util.c
+++ b/src/iperf_util.c
@@ -46,6 +46,8 @@
 #include <time.h>
 #include <errno.h>
 
+#include <zircon/syscalls.h>
+
 #include "cjson.h"
 
 /* make_cookie
@@ -65,13 +67,14 @@
     struct timeval tv;
     char temp[1000];
 
-    if ( ! randomized )
-        srandom((int) time(0) ^ getpid());
+    unsigned long int rand1, rand2;
+    zx_cprng_draw(&rand1, sizeof(rand1));
+    zx_cprng_draw(&rand2, sizeof(rand2));
 
     /* Generate a string based on hostname, time, randomness, and filler. */
     (void) gethostname(hostname, sizeof(hostname));
     (void) gettimeofday(&tv, 0);
-    (void) snprintf(temp, sizeof(temp), "%s.%ld.%06ld.%08lx%08lx.%s", hostname, (unsigned long int) tv.tv_sec, (unsigned long int) tv.tv_usec, (unsigned long int) random(), (unsigned long int) random(), "1234567890123456789012345678901234567890");
+    (void) snprintf(temp, sizeof(temp), "%s.%ld.%06ld.%08lx%08lx.%s", hostname, (unsigned long int) tv.tv_sec, (unsigned long int) tv.tv_usec, rand1, rand2, "1234567890123456789012345678901234567890");
 
     /* Now truncate it to 36 bytes and terminate. */
     memcpy(cookie, temp, 36);