add support for reverse name lookups from hosts file to getnameinfo

this also affects the legacy gethostbyaddr family, which uses
getnameinfo as its backend.

some other minor changes associated with the refactoring of source
files are also made; in particular, the resolv.conf parser now uses
the same code that's used elsewhere to handle ip literals, so as a
side effect it can now accept a scope id for nameserver addressed with
link-local scope.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/network/lookup_ipliteral.c b/src/network/lookup_ipliteral.c
new file mode 100644
index 00000000..8dacffc1
--- /dev/null
+++ b/src/network/lookup_ipliteral.c
@@ -0,0 +1,51 @@
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <net/if.h>
+#include <arpa/inet.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include "lookup.h"
+
+int __inet_aton(const char *, struct in_addr *);
+
+int __lookup_ipliteral(struct address buf[static 1], const char *name, int family)
+{
+	struct in_addr a4;
+	struct in6_addr a6;
+	if (family != AF_INET6 && __inet_aton(name, &a4)>0) {
+		memcpy(&buf[0].addr, &a4, sizeof a4);
+		buf[0].family = AF_INET;
+		buf[0].scopeid = 0;
+		return 1;
+	}
+	if (family != AF_INET) {
+		char tmp[64];
+		char *p = strchr(name, '%'), *z;
+		unsigned long long scopeid;
+		if (p && p-name < 64) {
+			memcpy(tmp, name, p-name);
+			tmp[p-name] = 0;
+			name = tmp;
+		}
+		if (inet_pton(AF_INET6, name, &a6)<=0) return 0;
+		memcpy(&buf[0].addr, &a6, sizeof a6);
+		buf[0].family = AF_INET6;
+		if (p) {
+			if (isdigit(*++p)) scopeid = strtoull(p, &z, 10);
+			else z = p-1;
+			if (*z) {
+				if (!IN6_IS_ADDR_LINKLOCAL(&a6) &&
+				    !IN6_IS_ADDR_MC_LINKLOCAL(&a6))
+					return EAI_NONAME;
+				scopeid = if_nametoindex(p);
+				if (!scopeid) return EAI_NONAME;
+			}
+			if (scopeid > UINT_MAX) return EAI_NONAME;
+			buf[0].scopeid = scopeid;
+		}
+		return 1;
+	}
+	return 0;
+}