Change in osmo-ggsn[master]: ggsn: Remove magic numbers from ipcp_contains_option()

[Harald Welte]

Harald Welte has uploaded this change for review. ( https://gerrit.osmocom.org/13569


Change subject: ggsn: Remove magic numbers from ipcp_contains_option()
......................................................................

ggsn: Remove magic numbers from ipcp_contains_option()

Let's remove some magic numbers and use a data structure instead.

Change-Id: I5b1abc6f403f85986407e9e8359924dfcb58031a
---
M ggsn/ggsn.c
1 file changed, 7 insertions(+), 6 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-ggsn refs/changes/69/13569/1

diff --git a/ggsn/ggsn.c b/ggsn/ggsn.c
index 2c0d64e..2d1368b 100644
--- a/ggsn/ggsn.c
+++ b/ggsn/ggsn.c
@@ -419,14 +419,15 @@
 	const uint8_t *cur_opt = ipcp + sizeof(struct ipcp_hdr);
 
 	/* iterate over Options and check if protocol contained */
-	while (cur_opt + 2 <= ipcp + ipcp_len) {
-		uint8_t type = cur_opt[0];
-		uint8_t len = cur_opt[1]; /* length value includes 2 bytes type/length */
-		if (len < 2)
+	while (cur_opt + sizeof(struct ipcp_option_hdr) <= ipcp + ipcp_len) {
+		const struct ipcp_option_hdr *cur_opt_hdr = (const struct ipcp_option_hdr *)cur_opt;
+		/* length value includes 2 bytes type/length */
+		if (cur_opt_hdr->len < sizeof(struct ipcp_option_hdr))
 			return NULL;
-		if (type == opt && len >= 2 + opt_minlen)
+		if (cur_opt_hdr->type == opt &&
+		    cur_opt_hdr->len >= sizeof(struct ipcp_option_hdr) + opt_minlen)
 			return cur_opt;
-		cur_opt += len;
+		cur_opt += cur_opt_hdr->len;
 	}
 	return NULL;
 }

-- 
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Gerrit-Project: osmo-ggsn
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I5b1abc6f403f85986407e9e8359924dfcb58031a
Gerrit-Change-Number: 13569
Gerrit-PatchSet: 1
Gerrit-Owner: Harald Welte <laforge at gnumonks.org>
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