From 9af97c057a717ca829ba81053af74bd705c6da79 Mon Sep 17 00:00:00 2001
From: Thomas Gschwantner <tharre3@gmail.com>
Date: Sun, 14 Apr 2019 03:31:20 +0200
Subject: Add ip_util.h

---
 ip_util.h | 125 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 ip_util.h

diff --git a/ip_util.h b/ip_util.h
new file mode 100644
index 0000000..5550610
--- /dev/null
+++ b/ip_util.h
@@ -0,0 +1,125 @@
+#ifndef __IP_UTIL_H__
+#define __IP_UTIL_H__
+
+#include <arpa/inet.h>
+#include <printf.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#pragma GCC diagnostic ignored "-Wformat"
+#pragma GCC diagnostic ignored "-Wformat-extra-args"
+
+static int __printf_arginfo(const struct printf_info *info, size_t n,
+			    int *argtypes, int *sz)
+{
+	if (n > 0)
+		argtypes[0] = PA_POINTER;
+
+	return 1;
+}
+
+static int __printf_output_b(FILE *stream, const struct printf_info *info,
+			     const void *const *args)
+{
+	uint64_t value = 0;
+	char buf[8 * sizeof(uintmax_t) + 1] = { 0 };
+
+	if (info->width == 0 || info->width % 8 != 0)
+		return -1;
+
+	memcpy(&value, *(unsigned char **)(args[0]), info->width / 8);
+
+	for (int i = 0; i < info->width; ++i)
+		buf[info->width - 1 - i] = '0' + ((value >> i) & 0x1);
+
+	return fprintf(stream, "%s", buf);
+}
+
+static int __printf_output_y(FILE *stream, const struct printf_info *info,
+			     const void *const *args)
+{
+	char buf[INET_ADDRSTRLEN];
+	struct in_addr ip;
+
+	if (!*(unsigned char **)(args[0]))
+		return fprintf(stream, "(nil)", buf);
+
+	memcpy(&ip, *(unsigned char **)(args[0]), sizeof ip);
+
+	inet_ntop(AF_INET, &ip.s_addr, buf, sizeof buf);
+
+	return fprintf(stream, "%s", buf);
+}
+
+static int __printf_output_Y(FILE *stream, const struct printf_info *info,
+			     const void *const *args)
+{
+	char buf[INET6_ADDRSTRLEN];
+	struct in6_addr ip;
+
+	if (!*(unsigned char **)(args[0]))
+		return fprintf(stream, "(nil)", buf);
+
+	memcpy(&ip, *(unsigned char **)(args[0]), sizeof ip);
+
+	inet_ntop(AF_INET6, &ip.s6_addr, buf, sizeof buf);
+
+	return fprintf(stream, "%s", buf);
+}
+
+static void __attribute__((constructor)) __custom_printf_init()
+{
+	register_printf_specifier('b', __printf_output_b, __printf_arginfo);
+	register_printf_specifier('y', __printf_output_y, __printf_arginfo);
+	register_printf_specifier('Y', __printf_output_Y, __printf_arginfo);
+}
+
+struct ip_from {
+	unsigned char ip[16];
+	struct ip_from *next;
+};
+
+static struct ip_from *start = NULL;
+static struct ip_from *end = NULL;
+
+static unsigned char *ip_from(uint8_t bits, char *ip_str)
+{
+	struct ip_from *res = malloc(sizeof *res);
+
+	inet_pton(bits == 32 ? AF_INET : AF_INET6, ip_str, &res->ip);
+
+	if (!end)
+		start = end = res;
+	else
+		end->next = res;
+
+	end = res;
+	res->next = NULL;
+
+	return res->ip;
+}
+
+static struct in_addr *ip4_from(char *ip_str)
+{
+	return (struct in_addr *)ip_from(32, ip_str);
+}
+
+static struct in6_addr *ip6_from(char *ip_str)
+{
+	return (struct in6_addr *)ip_from(128, ip_str);
+}
+
+static void __attribute__((destructor)) __free_ip_froms()
+{
+	struct ip_from *cur = start, *next;
+	while (cur) {
+		next = cur->next;
+		free(cur);
+		cur = next;
+	}
+}
+
+#endif
-- 
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