// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *      Generic address resolution 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>
 */

#include <linux/module.h>
#include <linux/hex.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;
        size_t 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;
        size_t 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);

bool inet_addr_is_any(struct sockaddr_storage *addr)
{
        if (addr->ss_family == AF_INET6) {
                struct sockaddr_in6 *in6 = (struct sockaddr_in6 *)addr;
                const struct sockaddr_in6 in6_any =
                        { .sin6_addr = IN6ADDR_ANY_INIT };

                if (!memcmp(in6->sin6_addr.s6_addr,
                            in6_any.sin6_addr.s6_addr, 16))
                        return true;
        } else if (addr->ss_family == AF_INET) {
                struct sockaddr_in *in = (struct sockaddr_in *)addr;

                if (in->sin_addr.s_addr == htonl(INADDR_ANY))
                        return true;
        } else {
                pr_warn("unexpected address family %u\n", addr->ss_family);
        }

        return false;
}
EXPORT_SYMBOL(inet_addr_is_any);

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, bool ipv6)
{
        if (skb->ip_summed != CHECKSUM_PARTIAL) {
                csum_replace_by_diff(sum, diff);
                if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr && !ipv6)
                        skb->csum = ~csum_sub(diff, skb->csum);
        } else if (pseudohdr) {
                *sum = ~csum_fold(csum_add(diff, csum_unfold(*sum)));
        }
}
EXPORT_SYMBOL(inet_proto_csum_replace_by_diff);