fixing -Wstrict-aliasing (part 1)

tpws/helpers.c

@@ -10,6 +10,7 @@
 #include <ifaddrs.h>
 #include <time.h>
 #include <sys/stat.h>
+#include <netinet/in.h>
 
 char *strncasestr(const char *s,const char *find, size_t slen)
 {
@@ -132,7 +133,7 @@ void print_addrinfo(const struct addrinfo *ai)
 bool saismapped(const struct sockaddr_in6 *sa)
 {
 	// ::ffff:1.2.3.4
-	return !memcmp(sa->sin6_addr.s6_addr,"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff",12);
+	return IN6_IS_ADDR_V4MAPPED(sa->sin6_addr.s6_addr);
 }
 bool samappedcmp(const struct sockaddr_in *sa1,const struct sockaddr_in6 *sa2)
 {
@@ -154,7 +155,7 @@ bool saconvmapped(struct sockaddr_storage *a)
 {
 	if ((a->ss_family == AF_INET6) && saismapped((struct sockaddr_in6*)a))
 	{
-		uint32_t ip4 = *(uint32_t*)(((struct sockaddr_in6*)a)->sin6_addr.s6_addr+12);
+		uint32_t ip4 = IN6_EXTRACT_MAP4(((struct sockaddr_in6*)a)->sin6_addr.s6_addr);
 		uint16_t port = ((struct sockaddr_in6*)a)->sin6_port;
 		a->ss_family = AF_INET;
 		((struct sockaddr_in*)a)->sin_addr.s_addr = ip4;
@@ -166,14 +167,14 @@ bool saconvmapped(struct sockaddr_storage *a)
 
 bool is_localnet(const struct sockaddr *a)
 {
-	// 0.0.0.0, ::ffff:0.0.0.0 = localhost in linux
+	// 127.0.0.0/8, ::1 = localhost
-	return (a->sa_family==AF_INET && (*(char*)&((struct sockaddr_in *)a)->sin_addr.s_addr==127 || !((struct sockaddr_in *)a)->sin_addr.s_addr)) ||
+	return (a->sa_family==AF_INET && IN_LOOPBACK(((struct sockaddr_in *)a)->sin_addr.s_addr)) ||
-		(a->sa_family==AF_INET6 && saismapped((struct sockaddr_in6 *)a) && (((struct sockaddr_in6 *)a)->sin6_addr.s6_addr[12]==127 || !*(uint32_t*)(((struct sockaddr_in6 *)a)->sin6_addr.s6_addr+12)));
+		(a->sa_family==AF_INET6 && IN6_IS_ADDR_LOOPBACK(((struct sockaddr_in6 *)a)->sin6_addr.s6_addr));
 }
 bool is_linklocal(const struct sockaddr_in6 *a)
 {
 	// fe80::/10
-	return a->sin6_addr.s6_addr[0]==0xFE && (a->sin6_addr.s6_addr[1] & 0xC0)==0x80;
+	return IN6_IS_ADDR_LINKLOCAL(a->sin6_addr.s6_addr);
 }
 bool is_private6(const struct sockaddr_in6* a)
 {

tpws/helpers.h

@@ -55,3 +55,16 @@ typedef struct
 } port_filter;
 bool pf_in_range(uint16_t port, const port_filter *pf);
 bool pf_parse(const char *s, port_filter *pf);
+
+#ifndef IN_LOOPBACK
+#define IN_LOOPBACK(a)          ((((uint32_t) (a)) & 0xff000000) == 0x7f000000)
+#endif
+
+#ifdef __GNUC__
+#define IN6_EXTRACT_MAP4(a) \
+  (__extension__                                                              \
+   ({ const struct in6_addr *__a = (const struct in6_addr *) (a);             \
+      (((const uint32_t *) (__a))[3]); }))
+#else
+#define IN6_EXTRACT_MAP4(a)	(((const uint32_t *) (a))[3])
+#endif