Avoid warnings from -fsanitize=integer in the hash functions.

[tinc] / src / subnet.c

diff --git a/src/subnet.c b/src/subnet.c
index 8c76637..ffc82a6 100644 (file)
--- a/src/subnet.c
+++ b/src/subnet.c
@@ -40,6 +40,14 @@ splay_tree_t subnet_tree = {
 
 /* Subnet lookup cache */
 
+static uint32_t wrapping_add32(uint32_t a, uint32_t b) {
+       return (uint32_t)((uint64_t)a + b);
+}
+
+static uint32_t wrapping_mul32(uint32_t a, uint32_t b) {
+       return (uint32_t)((uint64_t)a * b);
+}
+
 static uint32_t hash_function_ipv4_t(const ipv4_t *p) {
        /*
        This basic hash works because
@@ -51,7 +59,7 @@ static uint32_t hash_function_ipv4_t(const ipv4_t *p) {
 
 #if __BYTE_ORDER == __LITTLE_ENDIAN
        // 10.0.x.x/16 part
-       hash += halfwidth[1] * 0x9e370001UL;
+       hash = wrapping_add32(hash, wrapping_mul32(halfwidth[1], 0x9e370001U));
 
        // x.x.0.[0-255] part
 #if SUBNET_HASH_SIZE >= 0x10000
@@ -62,7 +70,7 @@ static uint32_t hash_function_ipv4_t(const ipv4_t *p) {
 #endif // _____LP64_____
 #else
        // 10.0.x.x/16 part
-       hash += halfwidth[0] * 0x9e370001UL;
+       hash = wrapping_add32(hash, wrapping_mul32(halfwidth[0], 0x9e370001U));
 
        // x.x.0.[0-255] part (ntohs is nop on big endian)
        return hash ^ halfwidth[1];
@@ -76,7 +84,7 @@ static uint32_t hash_function_ipv6_t(const ipv6_t *p) {
 
        for(int i = 0; i < 4; i++) {
                hash += fullwidth[i];
-               hash *= 0x9e370001UL;
+               hash = wrapping_mul32(hash, 0x9e370001U);
        }
 
        return hash;
@@ -88,7 +96,7 @@ static uint32_t hash_function_mac_t(const mac_t *p) {
 
        for(int i = 0; i < 3; i++) {
                hash += halfwidth[i];
-               hash *= 0x9e370001UL;
+               hash = wrapping_mul32(hash, 0x9e370001U);
        }
 
        return hash;