[dpdk-dev] [PATCH v2] net: be more restrictive in accepted ether string formats

[Stephen Hemminger <stephen@networkplumber.org>]

The current ether_unformat_addr code was based off of
BSD ether_aton. That version changed what was allowed
by the cmdline ether address parser.
For example, it allows dropping leading zeros.

Change the code to be more restrictive and only allow the fully
expanded standard formats.

Bugzilla ID: 324
Fixes: 596d31092d32 ("net: add function to convert string to ethernet address")
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
v2 - incorporate RFC review feedback
`
 lib/librte_net/rte_ether.c | 113 ++++++++++++++++++++++++-------------
 lib/librte_net/rte_ether.h |   3 +
 2 files changed, 78 insertions(+), 38 deletions(-)

diff --git a/lib/librte_net/rte_ether.c b/lib/librte_net/rte_ether.c
index 8d040173cfc6..ced65ed9f3cb 100644
--- a/lib/librte_net/rte_ether.c
+++ b/lib/librte_net/rte_ether.c
@@ -2,6 +2,8 @@
  * Copyright(c) 2010-2014 Intel Corporation
  */
 
+#include <stdbool.h>
+
 #include <rte_ether.h>
 #include <rte_errno.h>
 
@@ -29,50 +31,85 @@ rte_ether_format_addr(char *buf, uint16_t size,
 		 eth_addr->addr_bytes[5]);
 }
 
+static int8_t get_xdigit(char ch)
+{
+	if (ch >= '0' && ch <= '9')
+		return ch - '0';
+	if (ch >= 'a' && ch <= 'f')
+		return ch - 'a' + 10;
+	if (ch >= 'A' && ch <= 'F')
+		return ch - 'A' + 10;
+	return -1;
+}
+
+/* Convert 00:11:22:33:44:55 to ethernet address */
+static bool get_ether_addr6(const char *s0, struct rte_ether_addr *ea)
+{
+	const char *s = s0;
+	int i;
+
+	for (i = 0; i < RTE_ETHER_ADDR_LEN; i++) {
+		int8_t x;
+
+		x = get_xdigit(*s++);
+		if (x < 0)
+			return false;
+
+		ea->addr_bytes[i] = x << 4;
+		x = get_xdigit(*s++);
+		if (x < 0)
+			return false;
+		ea->addr_bytes[i] |= x;
+
+		if (i < RTE_ETHER_ADDR_LEN - 1 &&
+		    *s++ != ':')
+			return false;
+	}
+
+	/* return true if at end of string */
+	return *s == '\0';
+}
+
+/* Convert 0011:2233:4455 to ethernet address */
+static bool get_ether_addr3(const char *s, struct rte_ether_addr *ea)
+{
+	int i, j;
+
+	for (i = 0; i < RTE_ETHER_ADDR_LEN; i += 2) {
+		uint16_t w = 0;
+
+		for (j = 0; j < 4; j++) {
+			int8_t x;
+
+			x = get_xdigit(*s++);
+			if (x < 0)
+				return false;
+			w = (w << 4) | x;
+		}
+		ea->addr_bytes[i] = w >> 8;
+		ea->addr_bytes[i + 1] = w & 0xff;
+
+		if (i < RTE_ETHER_ADDR_LEN - 2 &&
+		    *s++ != ':')
+			return false;
+	}
+
+	return *s == '\0';
+}
+
 /*
  * Like ether_aton_r but can handle either
  * XX:XX:XX:XX:XX:XX or XXXX:XXXX:XXXX
+ * and is more restrictive.
  */
 int
 rte_ether_unformat_addr(const char *s, struct rte_ether_addr *ea)
 {
-	unsigned int o0, o1, o2, o3, o4, o5;
-	int n;
-
-	n = sscanf(s, "%x:%x:%x:%x:%x:%x",
-		    &o0, &o1, &o2, &o3, &o4, &o5);
-
-	if (n == 6) {
-		/* Standard format XX:XX:XX:XX:XX:XX */
-		if (o0 > UINT8_MAX || o1 > UINT8_MAX || o2 > UINT8_MAX ||
-		    o3 > UINT8_MAX || o4 > UINT8_MAX || o5 > UINT8_MAX) {
-			rte_errno = ERANGE;
-			return -1;
-		}
+	if (get_ether_addr6(s, ea))
+		return 0;
+	if (get_ether_addr3(s, ea))
+		return 0;
 
-		ea->addr_bytes[0] = o0;
-		ea->addr_bytes[1] = o1;
-		ea->addr_bytes[2] = o2;
-		ea->addr_bytes[3] = o3;
-		ea->addr_bytes[4] = o4;
-		ea->addr_bytes[5] = o5;
-	} else if (n == 3) {
-		/* Support the format XXXX:XXXX:XXXX */
-		if (o0 > UINT16_MAX || o1 > UINT16_MAX || o2 > UINT16_MAX) {
-			rte_errno = ERANGE;
-			return -1;
-		}
-
-		ea->addr_bytes[0] = o0 >> 8;
-		ea->addr_bytes[1] = o0 & 0xff;
-		ea->addr_bytes[2] = o1 >> 8;
-		ea->addr_bytes[3] = o1 & 0xff;
-		ea->addr_bytes[4] = o2 >> 8;
-		ea->addr_bytes[5] = o2 & 0xff;
-	} else {
-		/* unknown format */
-		rte_errno = EINVAL;
-		return -1;
-	}
-	return 0;
+	rte_errno = EINVAL;
+	return -1;
 }
diff --git a/lib/librte_net/rte_ether.h b/lib/librte_net/rte_ether.h
index 8ac1afecc826..c2f15c56c784 100644
--- a/lib/librte_net/rte_ether.h
+++ b/lib/librte_net/rte_ether.h
@@ -252,6 +252,9 @@ rte_ether_format_addr(char *buf, uint16_t size,
  *
  * @param str
  *   A pointer to buffer contains the formatted MAC address.
+ *   The supported formats are:
+ *     XX:XX:XX:XX:XX:XX or XXXX:XXXX:XXXX
+ *   where XX is a hex digit: 0-9, a-f, or A-F.
  * @param eth_addr
  *   A pointer to a ether_addr structure.
  * @return
-- 
2.17.1