Bug 1110212 - Strong randomness for Android DNS resolver. r=sworkman

This commit is contained in:
Eugen Sawin 2014-12-18 19:52:18 +01:00
parent a8d68856d3
commit c0f705209e

View File

@ -104,6 +104,7 @@ __RCSID("$NetBSD: res_init.c,v 1.8 2006/03/19 03:10:08 christos Exp $");
#include <arpa/inet.h>
#include "arpa_nameser.h"
#include <assert.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
@ -729,8 +730,50 @@ net_mask(in) /* XXX - should really use system's version of this */
return (htonl(IN_CLASSC_NET));
}
#ifdef ANDROID_CHANGES
/*
* Based on following AOSP Bionic changesets released with Android 4.1.1 r1
* - b23f193dcc0fa74b5be1978f85cc1c6811493c86 (bug 6535492)
* - 1781ed7774671d5a750839650b9582ff0abbcf42
*/
static int
real_randomid(u_int *random_value) {
/* open the nonblocking random device, returning -1 on failure */
int random_device = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
if (random_device < 0) {
return -1;
}
/* read from the random device, returning -1 on failure (or too many retries)*/
u_int retry = 5;
for (retry; retry > 0; retry--) {
int retval = read(random_device, random_value, sizeof(u_int));
if (retval == sizeof(u_int)) {
*random_value &= 0xffff;
close(random_device);
return 0;
} else if ((retval < 0) && (errno != EINTR)) {
break;
}
}
close(random_device);
return -1;
}
#endif /* ANDROID_CHANGES */
u_int
res_randomid(void) {
#ifdef ANDROID_CHANGES
int status = 0;
u_int output = 0;
status = real_randomid(&output);
if (status != -1) {
return output;
}
/* There was an unexpected issue with reading from /dev/urandom. */
assert(status != -1);
#endif /* ANDROID_CHANGES */
struct timeval now;
gettimeofday(&now, NULL);