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025599ec99
The general wisdom these days - in particular as given by the Linux urandom(4) man page - seems to be that there's no need to use the blocking /dev/random any more unless you're running at very early boot time when the system random pool is at serious risk of not having any entropy in it at all. In case of non-Linux systems that don't think /dev/urandom is a standard name, I fall back to /dev/random if /dev/urandom can't be found.
65 lines
1.3 KiB
C
65 lines
1.3 KiB
C
/*
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* uxgen.c: Unix implementation of get_heavy_noise() from cmdgen.c.
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*/
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#include <stdio.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "putty.h"
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char *get_random_data(int len, const char *device)
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{
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char *buf = snewn(len, char);
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int fd;
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int ngot, ret;
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if (!device) {
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static const char *const default_devices[] = {
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"/dev/urandom", "/dev/random"
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};
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size_t i;
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for (i = 0; i < lenof(default_devices); i++) {
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if (access(default_devices[i], R_OK) == 0) {
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device = default_devices[i];
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break;
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}
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}
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if (!device) {
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sfree(buf);
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fprintf(stderr, "puttygen: cannot find a readable "
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"random number source; use --random-device\n");
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return NULL;
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}
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}
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fd = open(device, O_RDONLY);
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if (fd < 0) {
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sfree(buf);
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fprintf(stderr, "puttygen: %s: open: %s\n",
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device, strerror(errno));
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return NULL;
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}
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ngot = 0;
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while (ngot < len) {
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ret = read(fd, buf+ngot, len-ngot);
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if (ret < 0) {
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close(fd);
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sfree(buf);
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fprintf(stderr, "puttygen: %s: read: %s\n",
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device, strerror(errno));
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return NULL;
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}
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ngot += ret;
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}
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close(fd);
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return buf;
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}
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