utils: Add random buffer generation function

Define and export the u_randbuf() function that fills a buffer with
random data.
Convert L2TP's challenge generation code for using it.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>

1 files changed, 30 insertions, 0 deletions

diff --git a/accel-pppd/utils.c b/accel-pppd/utils.c
index a6a76c93..45e8709c 100644
--- a/accel-pppd/utils.c
+++ b/accel-pppd/utils.c
@@ -1,12 +1,15 @@
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 #include "triton.h"
 #include "utils.h"
 
 #include "memdebug.h"
 
+extern int urandom_fd;
+
 void __export u_inet_ntoa(in_addr_t addr, char *str)
 {
 	sprintf(str, "%i.%i.%i.%i", addr & 0xff, (addr >> 8) & 0xff, (addr >> 16) & 0xff, (addr >> 24) & 0xff);
@@ -30,3 +33,30 @@ int __export u_readlong(long int *dst, const char *src,
                 return 0;
         }
 }
+
+int __export u_randbuf(void *buf, size_t buf_len, int *err)
+{
+	uint8_t *u8buf = buf;
+	ssize_t rd_len;
+
+	while (buf_len) {
+		rd_len = read(urandom_fd, u8buf, buf_len);
+		if (rd_len < 0) {
+			if (errno == EINTR)
+				rd_len = 0;
+			else {
+				if (err)
+					*err = errno;
+				return -1;
+			}
+		} else if (rd_len == 0) {
+			if (err)
+				*err = 0;
+			return -1;
+		}
+		u8buf += rd_len;
+		buf_len -= rd_len;
+	}
+
+	return 0;
+}