hashmap: refactor hash_func

All our hash functions are based on siphash24(), factor out
siphash_init() and siphash24_finalize() and pass the siphash
state to the hash functions rather than the hash key.

This simplifies the hash functions, and in particular makes
composition simpler as calling siphash24_compress() repeatedly
on separate chunks of input has the same effect as first
concatenating the input and then calling siphash23_compress()
on the result.

2 files changed, 9 insertions, 11 deletions

diff --git a/src/resolve/resolved-dns-rr.c b/src/resolve/resolved-dns-rr.c
index fd2f53f40b..2bc8cc1639 100644
--- a/src/resolve/resolved-dns-rr.c
+++ b/src/resolve/resolved-dns-rr.c
@@ -146,15 +146,14 @@ int dns_resource_key_match_cname(const DnsResourceKey *key, const DnsResourceRec
         return dns_name_equal(DNS_RESOURCE_KEY_NAME(rr->key), DNS_RESOURCE_KEY_NAME(key));
 }
 
-static unsigned long dns_resource_key_hash_func(const void *i, const uint8_t hash_key[HASH_KEY_SIZE]) {
+static void dns_resource_key_hash_func(const void *i, struct siphash *state) {
         const DnsResourceKey *k = i;
-        unsigned long ul;
 
-        ul = dns_name_hash_func(DNS_RESOURCE_KEY_NAME(k), hash_key);
-        ul = ul * hash_key[0] + ul + k->class;
-        ul = ul * hash_key[1] + ul + k->type;
+        assert(k);
 
-        return ul;
+        dns_name_hash_func(DNS_RESOURCE_KEY_NAME(k), state);
+        siphash24_compress(&k->class, sizeof(k->class), state);
+        siphash24_compress(&k->type, sizeof(k->type), state);
 }
 
 static int dns_resource_key_compare_func(const void *a, const void *b) {
diff --git a/src/resolve/resolved-dns-server.c b/src/resolve/resolved-dns-server.c
index 2ff5b192df..8693911e65 100644
--- a/src/resolve/resolved-dns-server.c
+++ b/src/resolve/resolved-dns-server.c
@@ -137,14 +137,13 @@ void dns_server_packet_lost(DnsServer *s, usec_t usec) {
                 s->resend_timeout = MIN(s->resend_timeout * 2, DNS_TIMEOUT_MAX_USEC);
 }
 
-static unsigned long dns_server_hash_func(const void *p, const uint8_t hash_key[HASH_KEY_SIZE]) {
+static void dns_server_hash_func(const void *p, struct siphash *state) {
         const DnsServer *s = p;
-        uint64_t u;
 
-        siphash24((uint8_t*) &u, &s->address, FAMILY_ADDRESS_SIZE(s->family), hash_key);
-        u = u * hash_key[0] + u + s->family;
+        assert(s);
 
-        return u;
+        siphash24_compress(&s->family, sizeof(s->family), state);
+        siphash24_compress(&s->address, FAMILY_ADDRESS_SIZE(s->family), state);
 }
 
 static int dns_server_compare_func(const void *a, const void *b) {