Remove magic constants from dns request parsing code

diff --git a/plugins/dnsproxy.c b/plugins/dnsproxy.c
index 5a77c5f..2cb2f41 100644 (file)
--- a/plugins/dnsproxy.c
+++ b/plugins/dnsproxy.c
@@ -401,6 +401,8 @@ static struct connman_notifier dnsproxy_notifier = {
        .offline_mode           = dnsproxy_offline_mode,
 };
 
+static unsigned char opt_edns0_type[2] = { 0x00, 0x29 };
+
 static int parse_request(unsigned char *buf, int len,
                                        char *name, unsigned int size)
 {
@@ -423,8 +425,8 @@ static int parse_request(unsigned char *buf, int len,
 
        memset(name, 0, size);
 
-       ptr = buf + 12;
-       remain = len - 12;
+       ptr = buf + sizeof(struct domain_hdr);
+       remain = len - sizeof(struct domain_hdr);
 
        while (remain > 0) {
                uint8_t len = *ptr;
@@ -447,7 +449,7 @@ static int parse_request(unsigned char *buf, int len,
        }
 
        if (last_label && arcount && remain >= 9 && last_label[4] == 0 &&
-                               last_label[5] == 0 && last_label[6] == 0x29) {
+                               !memcmp(last_label + 5, opt_edns0_type, 2)) {
                uint16_t edns0_bufsize;
 
                edns0_bufsize = last_label[7] << 8 | last_label[8];