adding revised avahi_keytag(), takes an AvahiRecord.

git-svn-id: file:///home/lennart/svn/public/avahi/branches/federico2@1733 941a03a8-eaeb-0310-b9a0-b1bbd8fe43fe

3 files changed, 44 insertions, 5 deletions

diff --git a/avahi-core/domain-util.c b/avahi-core/domain-util.c
index 7f562db..627ce5d 100644
--- a/avahi-core/domain-util.c
+++ b/avahi-core/domain-util.c
@@ -240,8 +240,8 @@ uint8_t avahi_count_canonical_labels(const char* input){
 }
 
 /* reference keytag generator from RFC 4034 */
-/* invoke with avahi_keytag(<rdata>, <rdlength>); */
-uint16_t avahi_keytag(uint8_t key[], uint16_t keysize){
+/* invoke with keytag(<rdata>, <rdlength>); */
+uint16_t keytag(uint8_t key[], uint16_t keysize){
     uint32_t ac;
     int i;
 
@@ -252,3 +252,38 @@ uint16_t avahi_keytag(uint8_t key[], uint16_t keysize){
 
     return ac & 0xFFFF;
    }
+
+/*invoke with avahi_keytag(<RR>); */
+uint16_t avahi_keytag(AvahiRecord r){
+    uint16_t result;
+    AvahiDNSPacket *tmp;
+
+    if (r->key.type != AVAHI_DNS_TYPE_RRSIG)
+        return NULL; /* invalid RRTYPE to generate keytag on */
+
+    p = avahi_dns_packet_new_query(0); /* MTU */
+
+    if (!p) { /*OOM check */
+      avahi_log_error("avahi_dns_packet_new_update() failed.");
+      assert(p);
+    }
+
+    /* no TTL binding, leave record unaltered */
+    result = avahi_dns_packet_append_record(tmp, key, 0, 0);
+
+    if (!result) {
+      avahi_log_error("appending of rdata failed.");
+      assert(result);
+    }
+
+    /* update RRSET we modified */
+    avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_ARCOUNT, 1);
+
+    /* finally, generate keytag */
+    /* first arg is rdata address, second arg is rdlength */
+    result = keytag(AVAHI_DNS_PACKET_DATA(tmp), sizeof(uint16_t) + 2*sizeof(uint8_t) + AVAHI_DNSSEC_SHA1_KEYLENGTH);
+
+    avahi_free(tmp);
+
+    return result;
+}
\ No newline at end of file
diff --git a/avahi-core/domain-util.h b/avahi-core/domain-util.h
index 2e4cf3d..1e71426 100644
--- a/avahi-core/domain-util.h
+++ b/avahi-core/domain-util.h
@@ -48,8 +48,11 @@ unsigned char * avahi_c_to_canonical_string(const char* input);
 /** returns the number of labels in a canonical DNS domain */
 uint8_t avahi_count_canonical_labels(const char* input);
 
+/** returns keytag of a given DNSKEY record */
+uint16_t avahi_keytag(AvahiRecord r);
+
 /* reference keytag generator from RFC 4034 */
-uint16_t avahi_keytag(uint8_t key[], uint16_t keysize)
+uint16_t avahi_keytag(uint8_t key[], uint16_t keysize);
 
 AVAHI_C_DECL_END
 
diff --git a/avahi-core/rr.h b/avahi-core/rr.h
index 2437ef2..2df7ba1 100644
--- a/avahi-core/rr.h
+++ b/avahi-core/rr.h
@@ -54,7 +54,8 @@ enum {
 enum {
     AVAHI_DNSSEC_PROTO = 0x3,
     AVAHI_DNSSEC_VALIDITY = 30,
-    AVAHI_DNSSEC_TIME_DRIFT = 3600
+    AVAHI_DNSSEC_TIME_DRIFT = 3600,
+    AVAHI_DNSSEC_SHA1_KEYLENGTH = 89
 };
 
 /** DNS record classes, see RFC 1035, in addition to those defined in defs.h */
@@ -134,7 +135,7 @@ typedef struct AvahiRecord {
             uint32_t signature_expiration;
             uint32_t signature_inception;
             uint16_t key_tag;
-            char* signers_name;
+            char* signers_name; /*uncompressed label */
             char* signature;
         } rrsig; /** data for rrsig record */