net/core/utils.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  *	Generic address resultion entity
  *
  *	Authors:
  *	net_random Alan Cox
  *	net_ratelimit Andi Kleen
  *	in{4,6}_pton YOSHIFUJI Hideaki, Copyright (C)2006 USAGI/WIDE Project
  *
  *	Created by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
  *
  *	This program is free software; you can redistribute it and/or
  *      modify it under the terms of the GNU General Public License
  *      as published by the Free Software Foundation; either version
  *      2 of the License, or (at your option) any later version.
  */

 #include <linux/module.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/ctype.h>
 #include <linux/inet.h>
 #include <linux/mm.h>
 #include <linux/net.h>
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/percpu.h>
 #include <linux/init.h>
 #include <linux/ratelimit.h>
 #include <linux/socket.h>

 #include <net/sock.h>
 #include <net/net_ratelimit.h>
 #include <net/ipv6.h>

 #include <asm/byteorder.h>
 #include <linux/uaccess.h>

 DEFINE_RATELIMIT_STATE(net_ratelimit_state, 5 * HZ, 10);
 /*
  * All net warning printk()s should be guarded by this function.
  */
 int net_ratelimit(void)
 {
 	return __ratelimit(&net_ratelimit_state);
 }
 EXPORT_SYMBOL(net_ratelimit);

 /*
  * Convert an ASCII string to binary IP.
  * This is outside of net/ipv4/ because various code that uses IP addresses
  * is otherwise not dependent on the TCP/IP stack.
  */

 __be32 in_aton(const char *str)
 {
 	unsigned int l;
 	unsigned int val;
 	int i;

 	l = 0;
 	for (i = 0; i < 4; i++)	{
 		l <<= 8;
 		if (*str != '\0') {
 			val = 0;
 			while (*str != '\0' && *str != '.' && *str != '\n') {
 				val *= 10;
 				val += *str - '0';
 				str++;
 			}
 			l |= val;
 			if (*str != '\0')
 				str++;
 		}
 	}
 	return htonl(l);
 }
 EXPORT_SYMBOL(in_aton);

 #define IN6PTON_XDIGIT		0x00010000
 #define IN6PTON_DIGIT		0x00020000
 #define IN6PTON_COLON_MASK	0x00700000
 #define IN6PTON_COLON_1		0x00100000	/* single : requested */
 #define IN6PTON_COLON_2		0x00200000	/* second : requested */
 #define IN6PTON_COLON_1_2	0x00400000	/* :: requested */
 #define IN6PTON_DOT		0x00800000	/* . */
 #define IN6PTON_DELIM		0x10000000
 #define IN6PTON_NULL		0x20000000	/* first/tail */
 #define IN6PTON_UNKNOWN		0x40000000

 static inline int xdigit2bin(char c, int delim)
 {
 	int val;

 	if (c == delim || c == '\0')
 		return IN6PTON_DELIM;
 	if (c == ':')
 		return IN6PTON_COLON_MASK;
 	if (c == '.')
 		return IN6PTON_DOT;

 	val = hex_to_bin(c);
 	if (val >= 0)
 		return val | IN6PTON_XDIGIT | (val < 10 ? IN6PTON_DIGIT : 0);

 	if (delim == -1)
 		return IN6PTON_DELIM;
 	return IN6PTON_UNKNOWN;
 }

 /**
  * in4_pton - convert an IPv4 address from literal to binary representation
  * @src: the start of the IPv4 address string
  * @srclen: the length of the string, -1 means strlen(src)
  * @dst: the binary (u8[4] array) representation of the IPv4 address
  * @delim: the delimiter of the IPv4 address in @src, -1 means no delimiter
  * @end: A pointer to the end of the parsed string will be placed here
  *
  * Return one on success, return zero when any error occurs
  * and @end will point to the end of the parsed string.
  *
  */
 int in4_pton(const char *src, int srclen,
 	     u8 *dst,
 	     int delim, const char **end)
 {
 	const char *s;
 	u8 *d;
 	u8 dbuf[4];
 	int ret = 0;
 	int i;
 	int w = 0;

 	if (srclen < 0)
 		srclen = strlen(src);
 	s = src;
 	d = dbuf;
 	i = 0;
 	while (1) {
 		int c;
 		c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
 		if (!(c & (IN6PTON_DIGIT | IN6PTON_DOT | IN6PTON_DELIM | IN6PTON_COLON_MASK))) {
 			goto out;
 		}
 		if (c & (IN6PTON_DOT | IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
 			if (w == 0)
 				goto out;
 			*d++ = w & 0xff;
 			w = 0;
 			i++;
 			if (c & (IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
 				if (i != 4)
 					goto out;
 				break;
 			}
 			goto cont;
 		}
 		w = (w * 10) + c;
 		if ((w & 0xffff) > 255) {
 			goto out;
 		}
 cont:
 		if (i >= 4)
 			goto out;
 		s++;
 		srclen--;
 	}
 	ret = 1;
 	memcpy(dst, dbuf, sizeof(dbuf));
 out:
 	if (end)
 		*end = s;
 	return ret;
 }
 EXPORT_SYMBOL(in4_pton);

 /**
  * in6_pton - convert an IPv6 address from literal to binary representation
  * @src: the start of the IPv6 address string
  * @srclen: the length of the string, -1 means strlen(src)
  * @dst: the binary (u8[16] array) representation of the IPv6 address
  * @delim: the delimiter of the IPv6 address in @src, -1 means no delimiter
  * @end: A pointer to the end of the parsed string will be placed here
  *
  * Return one on success, return zero when any error occurs
  * and @end will point to the end of the parsed string.
  *
  */
 int in6_pton(const char *src, int srclen,
 	     u8 *dst,
 	     int delim, const char **end)
 {
 	const char *s, *tok = NULL;
 	u8 *d, *dc = NULL;
 	u8 dbuf[16];
 	int ret = 0;
 	int i;
 	int state = IN6PTON_COLON_1_2 | IN6PTON_XDIGIT | IN6PTON_NULL;
 	int w = 0;

 	memset(dbuf, 0, sizeof(dbuf));

 	s = src;
 	d = dbuf;
 	if (srclen < 0)
 		srclen = strlen(src);

 	while (1) {
 		int c;

 		c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
 		if (!(c & state))
 			goto out;
 		if (c & (IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
 			/* process one 16-bit word */
 			if (!(state & IN6PTON_NULL)) {
 				*d++ = (w >> 8) & 0xff;
 				*d++ = w & 0xff;
 			}
 			w = 0;
 			if (c & IN6PTON_DELIM) {
 				/* We've processed last word */
 				break;
 			}
 			/*
 			 * COLON_1 => XDIGIT
 			 * COLON_2 => XDIGIT|DELIM
 			 * COLON_1_2 => COLON_2
 			 */
 			switch (state & IN6PTON_COLON_MASK) {
 			case IN6PTON_COLON_2:
 				dc = d;
 				state = IN6PTON_XDIGIT | IN6PTON_DELIM;
 				if (dc - dbuf >= sizeof(dbuf))
 					state |= IN6PTON_NULL;
 				break;
 			case IN6PTON_COLON_1|IN6PTON_COLON_1_2:
 				state = IN6PTON_XDIGIT | IN6PTON_COLON_2;
 				break;
 			case IN6PTON_COLON_1:
 				state = IN6PTON_XDIGIT;
 				break;
 			case IN6PTON_COLON_1_2:
 				state = IN6PTON_COLON_2;
 				break;
 			default:
 				state = 0;
 			}
 			tok = s + 1;
 			goto cont;
 		}

 		if (c & IN6PTON_DOT) {
 			ret = in4_pton(tok ? tok : s, srclen + (int)(s - tok), d, delim, &s);
 			if (ret > 0) {
 				d += 4;
 				break;
 			}
 			goto out;
 		}

 		w = (w << 4) | (0xff & c);
 		state = IN6PTON_COLON_1 | IN6PTON_DELIM;
 		if (!(w & 0xf000)) {
 			state |= IN6PTON_XDIGIT;
 		}
 		if (!dc && d + 2 < dbuf + sizeof(dbuf)) {
 			state |= IN6PTON_COLON_1_2;
 			state &= ~IN6PTON_DELIM;
 		}
 		if (d + 2 >= dbuf + sizeof(dbuf)) {
 			state &= ~(IN6PTON_COLON_1|IN6PTON_COLON_1_2);
 		}
 cont:
 		if ((dc && d + 4 < dbuf + sizeof(dbuf)) ||
 		    d + 4 == dbuf + sizeof(dbuf)) {
 			state |= IN6PTON_DOT;
 		}
 		if (d >= dbuf + sizeof(dbuf)) {
 			state &= ~(IN6PTON_XDIGIT|IN6PTON_COLON_MASK);
 		}
 		s++;
 		srclen--;
 	}

 	i = 15; d--;

 	if (dc) {
 		while (d >= dc)
 			dst[i--] = *d--;
 		while (i >= dc - dbuf)
 			dst[i--] = 0;
 		while (i >= 0)
 			dst[i--] = *d--;
 	} else
 		memcpy(dst, dbuf, sizeof(dbuf));

 	ret = 1;
 out:
 	if (end)
 		*end = s;
 	return ret;
 }
 EXPORT_SYMBOL(in6_pton);

 static int inet4_pton(const char *src, u16 port_num,
 		struct sockaddr_storage *addr)
 {
 	struct sockaddr_in *addr4 = (struct sockaddr_in *)addr;
 	int srclen = strlen(src);

 	if (srclen > INET_ADDRSTRLEN)
 		return -EINVAL;

 	if (in4_pton(src, srclen, (u8 *)&addr4->sin_addr.s_addr,
 		     '\n', NULL) == 0)
 		return -EINVAL;

 	addr4->sin_family = AF_INET;
 	addr4->sin_port = htons(port_num);

 	return 0;
 }

 static int inet6_pton(struct net *net, const char *src, u16 port_num,
 		struct sockaddr_storage *addr)
 {
 	struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)addr;
 	const char *scope_delim;
 	int srclen = strlen(src);

 	if (srclen > INET6_ADDRSTRLEN)
 		return -EINVAL;

 	if (in6_pton(src, srclen, (u8 *)&addr6->sin6_addr.s6_addr,
 		     '%', &scope_delim) == 0)
 		return -EINVAL;

 	if (ipv6_addr_type(&addr6->sin6_addr) & IPV6_ADDR_LINKLOCAL &&
 	    src + srclen != scope_delim && *scope_delim == '%') {
 		struct net_device *dev;
 		char scope_id[16];
 		size_t scope_len = min_t(size_t, sizeof(scope_id) - 1,
 					 src + srclen - scope_delim - 1);

 		memcpy(scope_id, scope_delim + 1, scope_len);
 		scope_id[scope_len] = '\0';

 		dev = dev_get_by_name(net, scope_id);
 		if (dev) {
 			addr6->sin6_scope_id = dev->ifindex;
 			dev_put(dev);
 		} else if (kstrtouint(scope_id, 0, &addr6->sin6_scope_id)) {
 			return -EINVAL;
 		}
 	}

 	addr6->sin6_family = AF_INET6;
 	addr6->sin6_port = htons(port_num);

 	return 0;
 }

 /**
  * inet_pton_with_scope - convert an IPv4/IPv6 and port to socket address
  * @net: net namespace (used for scope handling)
  * @af: address family, AF_INET, AF_INET6 or AF_UNSPEC for either
  * @src: the start of the address string
  * @port: the start of the port string (or NULL for none)
  * @addr: output socket address
  *
  * Return zero on success, return errno when any error occurs.
  */
 int inet_pton_with_scope(struct net *net, __kernel_sa_family_t af,
 		const char *src, const char *port, struct sockaddr_storage *addr)
 {
 	u16 port_num;
 	int ret = -EINVAL;

 	if (port) {
 		if (kstrtou16(port, 0, &port_num))
 			return -EINVAL;
 	} else {
 		port_num = 0;
 	}

 	switch (af) {
 	case AF_INET:
 		ret = inet4_pton(src, port_num, addr);
 		break;
 	case AF_INET6:
 		ret = inet6_pton(net, src, port_num, addr);
 		break;
 	case AF_UNSPEC:
 		ret = inet4_pton(src, port_num, addr);
 		if (ret)
 			ret = inet6_pton(net, src, port_num, addr);
 		break;
 	default:
 		pr_err("unexpected address family %d\n", af);
 	};

 	return ret;
 }
 EXPORT_SYMBOL(inet_pton_with_scope);

 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 			      __be32 from, __be32 to, bool pseudohdr)
 {
 	if (skb->ip_summed != CHECKSUM_PARTIAL) {
 		csum_replace4(sum, from, to);
 		if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
 			skb->csum = ~csum_add(csum_sub(~(skb->csum),
 						       (__force __wsum)from),
 					      (__force __wsum)to);
 	} else if (pseudohdr)
 		*sum = ~csum_fold(csum_add(csum_sub(csum_unfold(*sum),
 						    (__force __wsum)from),
 					   (__force __wsum)to));
 }
 EXPORT_SYMBOL(inet_proto_csum_replace4);

 /**
  * inet_proto_csum_replace16 - update layer 4 header checksum field
  * @sum: Layer 4 header checksum field
  * @skb: sk_buff for the packet
  * @from: old IPv6 address
  * @to: new IPv6 address
  * @pseudohdr: True if layer 4 header checksum includes pseudoheader
  *
  * Update layer 4 header as per the update in IPv6 src/dst address.
  *
  * There is no need to update skb->csum in this function, because update in two
  * fields a.) IPv6 src/dst address and b.) L4 header checksum cancels each other
  * for skb->csum calculation. Whereas inet_proto_csum_replace4 function needs to
  * update skb->csum, because update in 3 fields a.) IPv4 src/dst address,
  * b.) IPv4 Header checksum and c.) L4 header checksum results in same diff as
  * L4 Header checksum for skb->csum calculation.
  */
 void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
 			       const __be32 *from, const __be32 *to,
 			       bool pseudohdr)
 {
 	__be32 diff[] = {
 		~from[0], ~from[1], ~from[2], ~from[3],
 		to[0], to[1], to[2], to[3],
 	};
 	if (skb->ip_summed != CHECKSUM_PARTIAL) {
 		*sum = csum_fold(csum_partial(diff, sizeof(diff),
 				 ~csum_unfold(*sum)));
 	} else if (pseudohdr)
 		*sum = ~csum_fold(csum_partial(diff, sizeof(diff),
 				  csum_unfold(*sum)));
 }
 EXPORT_SYMBOL(inet_proto_csum_replace16);

 void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
 				     __wsum diff, bool pseudohdr)
 {
 	if (skb->ip_summed != CHECKSUM_PARTIAL) {
 		*sum = csum_fold(csum_add(diff, ~csum_unfold(*sum)));
 		if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
 			skb->csum = ~csum_add(diff, ~skb->csum);
 	} else if (pseudohdr) {
 		*sum = ~csum_fold(csum_add(diff, csum_unfold(*sum)));
 	}
 }
 EXPORT_SYMBOL(inet_proto_csum_replace_by_diff);
	/*
	* Generic address resultion entity
	*
	* Authors:
	* net_random Alan Cox
	* net_ratelimit Andi Kleen
	* in{4,6}_pton YOSHIFUJI Hideaki, Copyright (C)2006 USAGI/WIDE Project
	*
	* Created by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*/

	#include <linux/module.h>
	#include <linux/jiffies.h>
	#include <linux/kernel.h>
	#include <linux/ctype.h>
	#include <linux/inet.h>
	#include <linux/mm.h>
	#include <linux/net.h>
	#include <linux/string.h>
	#include <linux/types.h>
	#include <linux/percpu.h>
	#include <linux/init.h>
	#include <linux/ratelimit.h>
	#include <linux/socket.h>

	#include <net/sock.h>
	#include <net/net_ratelimit.h>
	#include <net/ipv6.h>

	#include <asm/byteorder.h>
	#include <linux/uaccess.h>

	DEFINE_RATELIMIT_STATE(net_ratelimit_state, 5 * HZ, 10);
	/*
	* All net warning printk()s should be guarded by this function.
	*/
	int net_ratelimit(void)
	{
	return __ratelimit(&net_ratelimit_state);
	}
	EXPORT_SYMBOL(net_ratelimit);

	/*
	* Convert an ASCII string to binary IP.
	* This is outside of net/ipv4/ because various code that uses IP addresses
	* is otherwise not dependent on the TCP/IP stack.
	*/

	__be32 in_aton(const char *str)
	{
	unsigned int l;
	unsigned int val;
	int i;

	l = 0;
	for (i = 0; i < 4; i++) {
	l <<= 8;
	if (*str != '\0') {
	val = 0;
	while (str != '\0' && str != '.' && *str != '\n') {
	val *= 10;
	val += *str - '0';
	str++;
	}
	l \|= val;
	if (*str != '\0')
	str++;
	}
	}
	return htonl(l);
	}
	EXPORT_SYMBOL(in_aton);

	#define IN6PTON_XDIGIT 0x00010000
	#define IN6PTON_DIGIT 0x00020000
	#define IN6PTON_COLON_MASK 0x00700000
	#define IN6PTON_COLON_1 0x00100000 /* single : requested */
	#define IN6PTON_COLON_2 0x00200000 /* second : requested */
	#define IN6PTON_COLON_1_2 0x00400000 /* :: requested */
	#define IN6PTON_DOT 0x00800000 /* . */
	#define IN6PTON_DELIM 0x10000000
	#define IN6PTON_NULL 0x20000000 /* first/tail */
	#define IN6PTON_UNKNOWN 0x40000000

	static inline int xdigit2bin(char c, int delim)
	{
	int val;

	if (c == delim \|\| c == '\0')
	return IN6PTON_DELIM;
	if (c == ':')
	return IN6PTON_COLON_MASK;
	if (c == '.')
	return IN6PTON_DOT;

	val = hex_to_bin(c);
	if (val >= 0)
	return val \| IN6PTON_XDIGIT \| (val < 10 ? IN6PTON_DIGIT : 0);

	if (delim == -1)
	return IN6PTON_DELIM;
	return IN6PTON_UNKNOWN;
	}

	/**
	* in4_pton - convert an IPv4 address from literal to binary representation
	* @src: the start of the IPv4 address string
	* @srclen: the length of the string, -1 means strlen(src)
	* @dst: the binary (u8[4] array) representation of the IPv4 address
	* @delim: the delimiter of the IPv4 address in @src, -1 means no delimiter
	* @end: A pointer to the end of the parsed string will be placed here
	*
	* Return one on success, return zero when any error occurs
	* and @end will point to the end of the parsed string.
	*
	*/
	int in4_pton(const char *src, int srclen,
	u8 *dst,
	int delim, const char **end)
	{
	const char *s;
	u8 *d;
	u8 dbuf[4];
	int ret = 0;
	int i;
	int w = 0;

	if (srclen < 0)
	srclen = strlen(src);
	s = src;
	d = dbuf;
	i = 0;
	while (1) {
	int c;
	c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
	if (!(c & (IN6PTON_DIGIT \| IN6PTON_DOT \| IN6PTON_DELIM \| IN6PTON_COLON_MASK))) {
	goto out;
	}
	if (c & (IN6PTON_DOT \| IN6PTON_DELIM \| IN6PTON_COLON_MASK)) {
	if (w == 0)
	goto out;
	*d++ = w & 0xff;
	w = 0;
	i++;
	if (c & (IN6PTON_DELIM \| IN6PTON_COLON_MASK)) {
	if (i != 4)
	goto out;
	break;
	}
	goto cont;
	}
	w = (w * 10) + c;
	if ((w & 0xffff) > 255) {
	goto out;
	}
	cont:
	if (i >= 4)
	goto out;
	s++;
	srclen--;
	}
	ret = 1;
	memcpy(dst, dbuf, sizeof(dbuf));
	out:
	if (end)
	*end = s;
	return ret;
	}
	EXPORT_SYMBOL(in4_pton);

	/**
	* in6_pton - convert an IPv6 address from literal to binary representation
	* @src: the start of the IPv6 address string
	* @srclen: the length of the string, -1 means strlen(src)
	* @dst: the binary (u8[16] array) representation of the IPv6 address
	* @delim: the delimiter of the IPv6 address in @src, -1 means no delimiter
	* @end: A pointer to the end of the parsed string will be placed here
	*
	* Return one on success, return zero when any error occurs
	* and @end will point to the end of the parsed string.
	*
	*/
	int in6_pton(const char *src, int srclen,
	u8 *dst,
	int delim, const char **end)
	{
	const char s, tok = NULL;
	u8 d, dc = NULL;
	u8 dbuf[16];
	int ret = 0;
	int i;
	int state = IN6PTON_COLON_1_2 \| IN6PTON_XDIGIT \| IN6PTON_NULL;
	int w = 0;

	memset(dbuf, 0, sizeof(dbuf));

	s = src;
	d = dbuf;
	if (srclen < 0)
	srclen = strlen(src);

	while (1) {
	int c;

	c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
	if (!(c & state))
	goto out;
	if (c & (IN6PTON_DELIM \| IN6PTON_COLON_MASK)) {
	/* process one 16-bit word */
	if (!(state & IN6PTON_NULL)) {
	*d++ = (w >> 8) & 0xff;
	*d++ = w & 0xff;
	}
	w = 0;
	if (c & IN6PTON_DELIM) {
	/* We've processed last word */
	break;
	}
	/*
	* COLON_1 => XDIGIT
	* COLON_2 => XDIGIT\|DELIM
	* COLON_1_2 => COLON_2
	*/
	switch (state & IN6PTON_COLON_MASK) {
	case IN6PTON_COLON_2:
	dc = d;
	state = IN6PTON_XDIGIT \| IN6PTON_DELIM;
	if (dc - dbuf >= sizeof(dbuf))
	state \|= IN6PTON_NULL;
	break;
	case IN6PTON_COLON_1\|IN6PTON_COLON_1_2:
	state = IN6PTON_XDIGIT \| IN6PTON_COLON_2;
	break;
	case IN6PTON_COLON_1:
	state = IN6PTON_XDIGIT;
	break;
	case IN6PTON_COLON_1_2:
	state = IN6PTON_COLON_2;
	break;
	default:
	state = 0;
	}
	tok = s + 1;
	goto cont;
	}

	if (c & IN6PTON_DOT) {
	ret = in4_pton(tok ? tok : s, srclen + (int)(s - tok), d, delim, &s);
	if (ret > 0) {
	d += 4;
	break;
	}
	goto out;
	}

	w = (w << 4) \| (0xff & c);
	state = IN6PTON_COLON_1 \| IN6PTON_DELIM;
	if (!(w & 0xf000)) {
	state \|= IN6PTON_XDIGIT;
	}
	if (!dc && d + 2 < dbuf + sizeof(dbuf)) {
	state \|= IN6PTON_COLON_1_2;
	state &= ~IN6PTON_DELIM;
	}
	if (d + 2 >= dbuf + sizeof(dbuf)) {
	state &= ~(IN6PTON_COLON_1\|IN6PTON_COLON_1_2);
	}
	cont:
	if ((dc && d + 4 < dbuf + sizeof(dbuf)) \|\|
	d + 4 == dbuf + sizeof(dbuf)) {
	state \|= IN6PTON_DOT;
	}
	if (d >= dbuf + sizeof(dbuf)) {
	state &= ~(IN6PTON_XDIGIT\|IN6PTON_COLON_MASK);
	}
	s++;
	srclen--;
	}

	i = 15; d--;

	if (dc) {
	while (d >= dc)
	dst[i--] = *d--;
	while (i >= dc - dbuf)
	dst[i--] = 0;
	while (i >= 0)
	dst[i--] = *d--;
	} else
	memcpy(dst, dbuf, sizeof(dbuf));

	ret = 1;
	out:
	if (end)
	*end = s;
	return ret;
	}
	EXPORT_SYMBOL(in6_pton);

	static int inet4_pton(const char *src, u16 port_num,
	struct sockaddr_storage *addr)
	{
	struct sockaddr_in addr4 = (struct sockaddr_in )addr;
	int srclen = strlen(src);

	if (srclen > INET_ADDRSTRLEN)
	return -EINVAL;

	if (in4_pton(src, srclen, (u8 *)&addr4->sin_addr.s_addr,
	'\n', NULL) == 0)
	return -EINVAL;

	addr4->sin_family = AF_INET;
	addr4->sin_port = htons(port_num);

	return 0;
	}

	static int inet6_pton(struct net net, const char src, u16 port_num,
	struct sockaddr_storage *addr)
	{
	struct sockaddr_in6 addr6 = (struct sockaddr_in6 )addr;
	const char *scope_delim;
	int srclen = strlen(src);

	if (srclen > INET6_ADDRSTRLEN)
	return -EINVAL;

	if (in6_pton(src, srclen, (u8 *)&addr6->sin6_addr.s6_addr,
	'%', &scope_delim) == 0)
	return -EINVAL;

	if (ipv6_addr_type(&addr6->sin6_addr) & IPV6_ADDR_LINKLOCAL &&
	src + srclen != scope_delim && *scope_delim == '%') {
	struct net_device *dev;
	char scope_id[16];
	size_t scope_len = min_t(size_t, sizeof(scope_id) - 1,
	src + srclen - scope_delim - 1);

	memcpy(scope_id, scope_delim + 1, scope_len);
	scope_id[scope_len] = '\0';

	dev = dev_get_by_name(net, scope_id);
	if (dev) {
	addr6->sin6_scope_id = dev->ifindex;
	dev_put(dev);
	} else if (kstrtouint(scope_id, 0, &addr6->sin6_scope_id)) {
	return -EINVAL;
	}
	}

	addr6->sin6_family = AF_INET6;
	addr6->sin6_port = htons(port_num);

	return 0;
	}

	/**
	* inet_pton_with_scope - convert an IPv4/IPv6 and port to socket address
	* @net: net namespace (used for scope handling)
	* @af: address family, AF_INET, AF_INET6 or AF_UNSPEC for either
	* @src: the start of the address string
	* @port: the start of the port string (or NULL for none)
	* @addr: output socket address
	*
	* Return zero on success, return errno when any error occurs.
	*/
	int inet_pton_with_scope(struct net *net, __kernel_sa_family_t af,
	const char src, const char port, struct sockaddr_storage *addr)
	{
	u16 port_num;
	int ret = -EINVAL;

	if (port) {
	if (kstrtou16(port, 0, &port_num))
	return -EINVAL;
	} else {
	port_num = 0;
	}

	switch (af) {
	case AF_INET:
	ret = inet4_pton(src, port_num, addr);
	break;
	case AF_INET6:
	ret = inet6_pton(net, src, port_num, addr);
	break;
	case AF_UNSPEC:
	ret = inet4_pton(src, port_num, addr);
	if (ret)
	ret = inet6_pton(net, src, port_num, addr);
	break;
	default:
	pr_err("unexpected address family %d\n", af);
	};

	return ret;
	}
	EXPORT_SYMBOL(inet_pton_with_scope);

	void inet_proto_csum_replace4(__sum16 sum, struct sk_buff skb,
	__be32 from, __be32 to, bool pseudohdr)
	{
	if (skb->ip_summed != CHECKSUM_PARTIAL) {
	csum_replace4(sum, from, to);
	if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
	skb->csum = ~csum_add(csum_sub(~(skb->csum),
	(__force __wsum)from),
	(__force __wsum)to);
	} else if (pseudohdr)
	sum = ~csum_fold(csum_add(csum_sub(csum_unfold(sum),
	(__force __wsum)from),
	(__force __wsum)to));
	}
	EXPORT_SYMBOL(inet_proto_csum_replace4);

	/**
	* inet_proto_csum_replace16 - update layer 4 header checksum field
	* @sum: Layer 4 header checksum field
	* @skb: sk_buff for the packet
	* @from: old IPv6 address
	* @to: new IPv6 address
	* @pseudohdr: True if layer 4 header checksum includes pseudoheader
	*
	* Update layer 4 header as per the update in IPv6 src/dst address.
	*
	* There is no need to update skb->csum in this function, because update in two
	* fields a.) IPv6 src/dst address and b.) L4 header checksum cancels each other
	* for skb->csum calculation. Whereas inet_proto_csum_replace4 function needs to
	* update skb->csum, because update in 3 fields a.) IPv4 src/dst address,
	* b.) IPv4 Header checksum and c.) L4 header checksum results in same diff as
	* L4 Header checksum for skb->csum calculation.
	*/
	void inet_proto_csum_replace16(__sum16 sum, struct sk_buff skb,
	const __be32 from, const __be32 to,
	bool pseudohdr)
	{
	__be32 diff[] = {
	~from[0], ~from[1], ~from[2], ~from[3],
	to[0], to[1], to[2], to[3],
	};
	if (skb->ip_summed != CHECKSUM_PARTIAL) {
	*sum = csum_fold(csum_partial(diff, sizeof(diff),
	~csum_unfold(*sum)));
	} else if (pseudohdr)
	*sum = ~csum_fold(csum_partial(diff, sizeof(diff),
	csum_unfold(*sum)));
	}
	EXPORT_SYMBOL(inet_proto_csum_replace16);

	void inet_proto_csum_replace_by_diff(__sum16 sum, struct sk_buff skb,
	__wsum diff, bool pseudohdr)
	{
	if (skb->ip_summed != CHECKSUM_PARTIAL) {
	sum = csum_fold(csum_add(diff, ~csum_unfold(sum)));
	if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
	skb->csum = ~csum_add(diff, ~skb->csum);
	} else if (pseudohdr) {
	sum = ~csum_fold(csum_add(diff, csum_unfold(sum)));
	}
	}
	EXPORT_SYMBOL(inet_proto_csum_replace_by_diff);