1 files changed, 71 insertions, 0 deletions
diff --git a/src/network/gethostbyaddr_r.c b/src/network/gethostbyaddr_r.c
new file mode 100644
index 00000000..cdb1d503
--- /dev/null
+++ b/src/network/gethostbyaddr_r.c
@@ -0,0 +1,71 @@
+#define _GNU_SOURCE
+
+#include <sys/socket.h>
+#include <netdb.h>
+#include <string.h>
+#include <netinet/in.h>
+#include <errno.h>
+#include <inttypes.h>
+
+int gethostbyaddr_r(const void *a, socklen_t l, int af,
+	struct hostent *h, char *buf, size_t buflen,
+	struct hostent **res, int *err)
+{
+	union {
+		struct sockaddr_in sin;
+		struct sockaddr_in6 sin6;
+	} sa = { .sin.sin_family = af };
+	socklen_t sl = af==AF_INET6 ? sizeof sa.sin6 : sizeof sa.sin;
+	int i;
+
+	/* Load address argument into sockaddr structure */
+	if (af==AF_INET6 && l==16) memcpy(&sa.sin6.sin6_addr, a, 16);
+	else if (af==AF_INET && l==4) memcpy(&sa.sin.sin_addr, a, 4);
+	else {
+		*err = NO_RECOVERY;
+		return -1;
+	}
+
+	/* Align buffer and check for space for pointers and ip address */
+	i = (uintptr_t)buf & sizeof(char *)-1;
+	if (!i) i = sizeof(char *);
+	if (buflen <= 5*sizeof(char *)-i + l) {
+		errno = ERANGE;
+		return -1;
+	}
+	buf += sizeof(char *)-i;
+	buflen -= 5*sizeof(char *)-i + l;
+
+	h->h_addr_list = (void *)buf;
+	buf += 2*sizeof(char *);
+	h->h_aliases = (void *)buf;
+	buf += 2*sizeof(char *);
+
+	h->h_addr_list[0] = buf;
+	memcpy(h->h_addr_list[0], a, l);
+	buf += l;
+	h->h_addr_list[1] = 0;
+	h->h_aliases[0] = buf;
+	h->h_aliases[1] = 0;
+
+	switch (getnameinfo((void *)&sa, sl, buf, buflen, 0, 0, 0)) {
+	case EAI_AGAIN:
+		*err = TRY_AGAIN;
+		return -1;
+	case EAI_OVERFLOW:
+		errno = ERANGE;
+	default:
+	case EAI_MEMORY:
+	case EAI_SYSTEM:
+	case EAI_FAIL:
+		*err = NO_RECOVERY;
+		return -1;
+	case 0:
+		break;
+	}
+
+	h->h_addrtype = af;
+	h->h_name = h->h_aliases[0];
+	*res = h;
+	return 0;
+}