/*
 * Copyright 2009, Oracle.  All rights reserved.
 *
 * Convert socket addresses to presentation addresses and universal
 * addresses, and vice versa.
 *
 * Universal addresses are introduced by RFC 1833 and further refined by
 * recent RFCs describing NFSv4.  The universal address format is part
 * of the external (network) interface provided by rpcbind version 3
 * and 4, and by NFSv4.  Such an address is a string containing a
 * presentation format IP address followed by a port number in
 * "hibyte.lobyte" format.
 *
 * IPv6 addresses can also include a scope ID, typically denoted by
 * a '%' followed by a device name or a non-negative integer.  Refer to
 * RFC 4291, Section 2.2 for details on IPv6 presentation formats.
 */

#include <net/ipv6.h>
#include <linux/sunrpc/clnt.h>
#include <linux/slab.h>
#include <linux/export.h>

#if IS_ENABLED(CONFIG_IPV6)

static size_t rpc_ntop6_noscopeid(const struct sockaddr *sap,
                                  char *buf, const int buflen)
{
        const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
        const struct in6_addr *addr = &sin6->sin6_addr;

        /*
         * RFC 4291, Section 2.2.2
         *
         * Shorthanded ANY address
         */
        if (ipv6_addr_any(addr))
                return snprintf(buf, buflen, "::");

        /*
         * RFC 4291, Section 2.2.2
         *
         * Shorthanded loopback address
         */
        if (ipv6_addr_loopback(addr))
                return snprintf(buf, buflen, "::1");

        /*
         * RFC 4291, Section 2.2.3
         *
         * Special presentation address format for mapped v4
         * addresses.
         */
        if (ipv6_addr_v4mapped(addr))
                return snprintf(buf, buflen, "::ffff:%pI4",
                                        &addr->s6_addr32[3]);

        /*
         * RFC 4291, Section 2.2.1
         */
        return snprintf(buf, buflen, "%pI6c", addr);
}

static size_t rpc_ntop6(const struct sockaddr *sap,
                        char *buf, const size_t buflen)
{
        const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
        char scopebuf[IPV6_SCOPE_ID_LEN];
        size_t len;
        int rc;

        len = rpc_ntop6_noscopeid(sap, buf, buflen);
        if (unlikely(len == 0))
                return len;

        if (!(ipv6_addr_type(&sin6->sin6_addr) & IPV6_ADDR_LINKLOCAL))
                return len;
        if (sin6->sin6_scope_id == 0)
                return len;

        rc = snprintf(scopebuf, sizeof(scopebuf), "%c%u",
                        IPV6_SCOPE_DELIMITER, sin6->sin6_scope_id);
        if (unlikely((size_t)rc > sizeof(scopebuf)))
                return 0;

        len += rc;
        if (unlikely(len > buflen))
                return 0;

        strcat(buf, scopebuf);
        return len;
}

#else   /* !IS_ENABLED(CONFIG_IPV6) */

static size_t rpc_ntop6_noscopeid(const struct sockaddr *sap,
                                  char *buf, const int buflen)
{
        return 0;
}

static size_t rpc_ntop6(const struct sockaddr *sap,
                        char *buf, const size_t buflen)
{
        return 0;
}

#endif  /* !IS_ENABLED(CONFIG_IPV6) */

static int rpc_ntop4(const struct sockaddr *sap,
                     char *buf, const size_t buflen)
{
        const struct sockaddr_in *sin = (struct sockaddr_in *)sap;

        return snprintf(buf, buflen, "%pI4", &sin->sin_addr);
}

/**
 * rpc_ntop - construct a presentation address in @buf
 * @sap: socket address
 * @buf: construction area
 * @buflen: size of @buf, in bytes
 *
 * Plants a %NUL-terminated string in @buf and returns the length
 * of the string, excluding the %NUL.  Otherwise zero is returned.
 */
size_t rpc_ntop(const struct sockaddr *sap, char *buf, const size_t buflen)
{
        switch (sap->sa_family) {
        case AF_INET:
                return rpc_ntop4(sap, buf, buflen);
        case AF_INET6:
                return rpc_ntop6(sap, buf, buflen);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(rpc_ntop);

static size_t rpc_pton4(const char *buf, const size_t buflen,
                        struct sockaddr *sap, const size_t salen)
{
        struct sockaddr_in *sin = (struct sockaddr_in *)sap;
        u8 *addr = (u8 *)&sin->sin_addr.s_addr;

        if (buflen > INET_ADDRSTRLEN || salen < sizeof(struct sockaddr_in))
                return 0;

        memset(sap, 0, sizeof(struct sockaddr_in));

        if (in4_pton(buf, buflen, addr, '\0', NULL) == 0)
                return 0;

        sin->sin_family = AF_INET;
        return sizeof(struct sockaddr_in);
}

#if IS_ENABLED(CONFIG_IPV6)
static int rpc_parse_scope_id(struct net *net, const char *buf,
                              const size_t buflen, const char *delim,
                              struct sockaddr_in6 *sin6)
{
        char *p;
        size_t len;

        if ((buf + buflen) == delim)
                return 1;

        if (*delim != IPV6_SCOPE_DELIMITER)
                return 0;

        if (!(ipv6_addr_type(&sin6->sin6_addr) & IPV6_ADDR_LINKLOCAL))
                return 0;

        len = (buf + buflen) - delim - 1;
        p = kstrndup(delim + 1, len, GFP_KERNEL);
        if (p) {
                unsigned long scope_id = 0;
                struct net_device *dev;

                dev = dev_get_by_name(net, p);
                if (dev != NULL) {
                        scope_id = dev->ifindex;
                        dev_put(dev);
                } else {
                        if (strict_strtoul(p, 10, &scope_id) == 0) {
                                kfree(p);
                                return 0;
                        }
                }

                kfree(p);

                sin6->sin6_scope_id = scope_id;
                return 1;
        }

        return 0;
}

static size_t rpc_pton6(struct net *net, const char *buf, const size_t buflen,
                        struct sockaddr *sap, const size_t salen)
{
        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
        u8 *addr = (u8 *)&sin6->sin6_addr.in6_u;
        const char *delim;

        if (buflen > (INET6_ADDRSTRLEN + IPV6_SCOPE_ID_LEN) ||
            salen < sizeof(struct sockaddr_in6))
                return 0;

        memset(sap, 0, sizeof(struct sockaddr_in6));

        if (in6_pton(buf, buflen, addr, IPV6_SCOPE_DELIMITER, &delim) == 0)
                return 0;

        if (!rpc_parse_scope_id(net, buf, buflen, delim, sin6))
                return 0;

        sin6->sin6_family = AF_INET6;
        return sizeof(struct sockaddr_in6);
}
#else
static size_t rpc_pton6(struct net *net, const char *buf, const size_t buflen,
                        struct sockaddr *sap, const size_t salen)
{
        return 0;
}
#endif

/**
 * rpc_pton - Construct a sockaddr in @sap
 * @net: applicable network namespace
 * @buf: C string containing presentation format IP address
 * @buflen: length of presentation address in bytes
 * @sap: buffer into which to plant socket address
 * @salen: size of buffer in bytes
 *
 * Returns the size of the socket address if successful; otherwise
 * zero is returned.
 *
 * Plants a socket address in @sap and returns the size of the
 * socket address, if successful.  Returns zero if an error
 * occurred.
 */
size_t rpc_pton(struct net *net, const char *buf, const size_t buflen,
                struct sockaddr *sap, const size_t salen)
{
        unsigned int i;

        for (i = 0; i < buflen; i++)
                if (buf[i] == ':')
                        return rpc_pton6(net, buf, buflen, sap, salen);
        return rpc_pton4(buf, buflen, sap, salen);
}
EXPORT_SYMBOL_GPL(rpc_pton);

/**
 * rpc_sockaddr2uaddr - Construct a universal address string from @sap.
 * @sap: socket address
 * @gfp_flags: allocation mode
 *
 * Returns a %NUL-terminated string in dynamically allocated memory;
 * otherwise NULL is returned if an error occurred.  Caller must
 * free the returned string.
 */
char *rpc_sockaddr2uaddr(const struct sockaddr *sap, gfp_t gfp_flags)
{
        char portbuf[RPCBIND_MAXUADDRPLEN];
        char addrbuf[RPCBIND_MAXUADDRLEN];
        unsigned short port;

        switch (sap->sa_family) {
        case AF_INET:
                if (rpc_ntop4(sap, addrbuf, sizeof(addrbuf)) == 0)
                        return NULL;
                port = ntohs(((struct sockaddr_in *)sap)->sin_port);
                break;
        case AF_INET6:
                if (rpc_ntop6_noscopeid(sap, addrbuf, sizeof(addrbuf)) == 0)
                        return NULL;
                port = ntohs(((struct sockaddr_in6 *)sap)->sin6_port);
                break;
        default:
                return NULL;
        }

        if (snprintf(portbuf, sizeof(portbuf),
                     ".%u.%u", port >> 8, port & 0xff) > (int)sizeof(portbuf))
                return NULL;

        if (strlcat(addrbuf, portbuf, sizeof(addrbuf)) > sizeof(addrbuf))
                return NULL;

        return kstrdup(addrbuf, gfp_flags);
}

/**
 * rpc_uaddr2sockaddr - convert a universal address to a socket address.
 * @net: applicable network namespace
 * @uaddr: C string containing universal address to convert
 * @uaddr_len: length of universal address string
 * @sap: buffer into which to plant socket address
 * @salen: size of buffer
 *
 * @uaddr does not have to be '\0'-terminated, but strict_strtoul() and
 * rpc_pton() require proper string termination to be successful.
 *
 * Returns the size of the socket address if successful; otherwise
 * zero is returned.
 */
size_t rpc_uaddr2sockaddr(struct net *net, const char *uaddr,
                          const size_t uaddr_len, struct sockaddr *sap,
                          const size_t salen)
{
        char *c, buf[RPCBIND_MAXUADDRLEN + sizeof('\0')];
        unsigned long portlo, porthi;
        unsigned short port;

        if (uaddr_len > RPCBIND_MAXUADDRLEN)
                return 0;

        memcpy(buf, uaddr, uaddr_len);

        buf[uaddr_len] = '\0';
        c = strrchr(buf, '.');
        if (unlikely(c == NULL))
                return 0;
        if (unlikely(strict_strtoul(c + 1, 10, &portlo) != 0))
                return 0;
        if (unlikely(portlo > 255))
                return 0;

        *c = '\0';
        c = strrchr(buf, '.');
        if (unlikely(c == NULL))
                return 0;
        if (unlikely(strict_strtoul(c + 1, 10, &porthi) != 0))
                return 0;
        if (unlikely(porthi > 255))
                return 0;

        port = (unsigned short)((porthi << 8) | portlo);

        *c = '\0';
        if (rpc_pton(net, buf, strlen(buf), sap, salen) == 0)
                return 0;

        switch (sap->sa_family) {
        case AF_INET:
                ((struct sockaddr_in *)sap)->sin_port = htons(port);
                return sizeof(struct sockaddr_in);
        case AF_INET6:
                ((struct sockaddr_in6 *)sap)->sin6_port = htons(port);
                return sizeof(struct sockaddr_in6);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(rpc_uaddr2sockaddr);