[PATCH] Simplify display of IPv6 addresses based on international standard

[zhousiqi (A)]

Dear BusyBox maintainers,

I am writing to propose a patch for dhcpc6 that simplifies the display of IPv6 addresses based on the international standard. Currently, when dhcpc6 obtains an IPv6 address, it displays the address in a full format, which can be difficult to read and compare. With this patch, the address will be displayed in a simplified format that is easier to read and understand.

I have tested this patch on my own system and have not encountered any issues. However, I welcome any feedback or suggestions from the community.

Thank you for considering my proposal.
																						Best regards,
																						Zhou


>From 757b2901fd397399f6b050a015767d2355a6f36e Mon Sep 17 00:00:00 2001
From: Zhou Siqi <zhousiqi5 at huawei.com>
Date: Tue, 6 Jun 2023 15:49:59 +0800
Subject: [PATCH] Currently, udhcpc6 does not support simplified IPv6 address
 based on standards. This modification enables udhcpc6 to support this
 function.

Signed-off-by: Zhou Siqi <zhousiqi5 at huawei.com>
---
 networking/udhcp/Config.src |  7 +++++++
 networking/udhcp/common.c   | 19 ++++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/networking/udhcp/Config.src b/networking/udhcp/Config.src
index 574c33c..c4bb89f 100644
--- a/networking/udhcp/Config.src
+++ b/networking/udhcp/Config.src
@@ -179,3 +179,10 @@ config FEATURE_UDHCPC6_RFC4075
 	help
 	If selected, the IPv6 client udhcpc6 can obtain the SNTP servers.
 
+config FEATURE_UDHCPC6_SIMPLIFY
+	bool "Support udhcpc6 simplified ipv6 address"
+	default y
+	depends on UDHCPC6
+	help
+	If selected, the IPv6 client udhcpc6 can simplify IPv6 addresses 
+	based on international standards.
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index 31e525c..e457734 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -5,6 +5,9 @@
  * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 #include "common.h"
+#if ENABLE_FEATURE_UDHCPC6_SIMPLIFY
+#include <netinet/in.h>
+#endif
 
 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 unsigned dhcp_verbose;
@@ -704,8 +707,12 @@ int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg,
 int FAST_FUNC sprint_nip6(char *dest, /*const char *pre,*/ const uint8_t *ip)
 {
 	char hexstrbuf[16 * 2];
+#if ENABLE_FEATURE_UDHCPC6_SIMPLIFY
+	struct in6_addr addr;
+	char compressed_address[INET6_ADDRSTRLEN];
+#endif
 	bin2hex(hexstrbuf, (void*)ip, 16);
-	return sprintf(dest, /* "%s" */
+	sprintf(dest, /* "%s" */
 		"%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s",
 		/* pre, */
 		hexstrbuf + 0 * 4,
@@ -717,4 +724,14 @@ int FAST_FUNC sprint_nip6(char *dest, /*const char *pre,*/ const uint8_t *ip)
 		hexstrbuf + 6 * 4,
 		hexstrbuf + 7 * 4
 	);
+#if ENABLE_FEATURE_UDHCPC6_SIMPLIFY
+	inet_pton(AF_INET6, dest, &addr);
+	inet_ntop(AF_INET6, &addr, compressed_address, INET6_ADDRSTRLEN);
+	/* If dest is different from compressed_address, the simplified address is valid. 
+	 * In this case, assign the simplified address to dest.
+	 */
+	if (strcmp(dest, compressed_address) != 0)
+		strcpy(dest,compressed_address);
+#endif
+	return strlen(dest);
 }
-- 
2.12.3