From: Arran Cudbard-Bell <a.cudbardb@freeradius.org>
Date: Thu, 5 Mar 2020 23:55:18 +0000 (-0600)
Subject: misc: Add htonx and ntohx
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=aa7caef0ec57d5ce1ef29b0de1ab94426178a501;p=thirdparty%2Ffreeradius-server.git

misc: Add htonx and ntohx

For efficient packing and unpacking of network order integers, where the integer is of a variable size.
---

diff --git a/src/lib/util/misc.h b/src/lib/util/misc.h
index 34ce824e458..9680aa0ad59 100644
--- a/src/lib/util/misc.h
+++ b/src/lib/util/misc.h
@@ -35,6 +35,7 @@ extern "C" {
 #include <ctype.h>
 #include <signal.h>
 #include <stdbool.h>
+#include <strings.h>
 #include <talloc.h>
 
 typedef		int8_t (*fr_cmp_t)(void const *a, void const *b);
@@ -167,6 +168,104 @@ static inline bool is_zero(char const *value)
 	return true;
 }
 
+/** Encode a 64bit unsigned integer as a big endian number in the fewest bytes possible
+ *
+ * @param[out] out	Where to write big endian encoding of num.
+ *			Should be at least 8 bytes.
+ * @param[in] num	Number to encode.
+ * @return
+ *	- The number of bytes written to out.
+ */
+static inline size_t htonx(uint8_t *out, uint64_t num)
+{
+	size_t ret;
+
+	/*
+	 *	flsll isn't POSIX, but it's in at least
+	 *	Linux, FreeBSD, OpenBSD and Solaris.
+	 *
+	 *	If we really care, implementing it
+	 *	in missing.c is trivial.
+	 *
+	 *	This version however should compile down
+	 *	to a single CPU instruction on supported
+	 *	platforms.
+	 */
+	ret = ROUND_UP_DIV((size_t)flsll((long long)num), 8);
+	switch (ret) {
+	case 8:
+		out[7] = (num & 0xFF00000000000000) >> 56;
+	/* FALL-THROUGH */
+	case 7:
+		out[6] = (num & 0xFF000000000000) >> 48;
+	/* FALL-THROUGH */
+	case 6:
+		out[5] = (num & 0xFF0000000000) >> 40;
+	/* FALL-THROUGH */
+	case 5:
+		out[4] = (num & 0xFF00000000) >> 32;
+	/* FALL-THROUGH */
+	case 4:
+		out[3] = (num & 0xFF000000) >> 24;
+	/* FALL-THROUGH */
+	case 3:
+		out[2] = (num & 0xFF0000) >> 16;
+	/* FALL-THROUGH */
+	case 2:
+		out[1] = (num & 0xFF00) >> 8;
+	/* FALL-THROUGH */
+	case 1:
+		out[0] = (num & 0xFF);
+		return ret;
+
+	case 0:
+		out[0] = 0;
+		return 1;
+	}
+
+	return 0;
+}
+
+/** Convert a big endian number of variable size to a unsigned 64bit integer of native endianness
+ *
+ * @param[in] data	Buffer containing the number.
+ * @param[in] data_len	Length of number.
+ * @return unsigned 64bit integer.
+ */
+static inline uint64_t ntohx(uint8_t const *data, size_t data_len)
+{
+	uint64_t ret = 0;
+
+	switch (data_len) {
+	case 8:
+		ret += ((uint64_t)data[7]) << 56;
+	/* FALL-THROUGH */
+	case 7:
+		ret += ((uint64_t)data[6]) << 48;
+	/* FALL-THROUGH */
+	case 6:
+		ret += ((uint64_t)data[5]) << 40;
+	/* FALL-THROUGH */
+	case 5:
+		ret += ((uint64_t)data[4]) << 32;
+	/* FALL-THROUGH */
+	case 4:
+		ret += ((uint64_t)data[3]) << 24;
+	/* FALL-THROUGH */
+	case 3:
+		ret += ((uint64_t)data[2]) << 16;
+	/* FALL-THROUGH */
+	case 2:
+		ret += ((uint64_t)data[1]) << 8;
+	/* FALL-THROUGH */
+	case 1:
+		ret += data[8];
+		return ret;
+	}
+
+	return 0;
+}
+
 int		fr_set_signal(int sig, sig_t func);
 int		fr_unset_signal(int sig);
 int		rad_lockfd(int fd, int lock_len);