openvswitch/lib/ofpbuf.h

/*
 * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef OFPBUF_H
#define OFPBUF_H 1

#include <stddef.h>
#include <stdint.h>
#include "list.h"
#include "packets.h"
#include "util.h"
#include "netdev-dpdk.h"

#ifdef  __cplusplus
extern "C" {
#endif

enum OVS_PACKED_ENUM ofpbuf_source {
    OFPBUF_MALLOC,              /* Obtained via malloc(). */
    OFPBUF_STACK,               /* Un-movable stack space or static buffer. */
    OFPBUF_STUB,                /* Starts on stack, may expand into heap. */
    OFPBUF_DPDK,                /* buffer data is from DPDK allocated memory.
                                   ref to build_ofpbuf() in netdev-dpdk. */
};

/* Buffer for holding arbitrary data.  An ofpbuf is automatically reallocated
 * as necessary if it grows too large for the available memory.
 *
 * 'frame' and offset conventions:
 *
 * Network frames (aka "packets"): 'frame' MUST be set to the start of the
 *    packet, layer offsets MAY be set as appropriate for the packet.
 *    Additionally, we assume in many places that the 'frame' and 'data' are
 *    the same for packets.
 *
 * OpenFlow messages: 'frame' points to the start of the OpenFlow
 *    header, while 'l3_ofs' is the length of the OpenFlow header.
 *    When parsing, the 'data' will move past these, as data is being
 *    pulled from the OpenFlow message.
 *
 * Actions: When encoding OVS action lists, the 'frame' is used
 *    as a pointer to the beginning of the current action (see ofpact_put()).
 *
 * rconn: Reuses 'frame' as a private pointer while queuing.
 */
struct ofpbuf {
#ifdef DPDK_NETDEV
    struct rte_mbuf mbuf;       /* DPDK mbuf */
#else
    void *base_;                 /* First byte of allocated space. */
    void *data_;                 /* First byte actually in use. */
    uint32_t size_;              /* Number of bytes in use. */
#endif
    uint32_t allocated;         /* Number of bytes allocated. */

    void *frame;                /* Packet frame start, or NULL. */
    enum ofpbuf_source source;  /* Source of memory allocated as 'base'. */
    uint8_t l2_pad_size;        /* Detected l2 padding size.
                                 * Padding is non-pullable. */
    uint16_t l2_5_ofs;          /* MPLS label stack offset from 'frame', or
                                 * UINT16_MAX */
    uint16_t l3_ofs;            /* Network-level header offset from 'frame',
                                   or UINT16_MAX. */
    uint16_t l4_ofs;            /* Transport-level header offset from 'frame',
                                   or UINT16_MAX. */
    struct ovs_list list_node;  /* Private list element for use by owner. */
};

static inline void * ofpbuf_data(const struct ofpbuf *);
static inline void ofpbuf_set_data(struct ofpbuf *, void *);
static inline void * ofpbuf_base(const struct ofpbuf *);
static inline void ofpbuf_set_base(struct ofpbuf *, void *);

static inline uint32_t ofpbuf_size(const struct ofpbuf *);
static inline void ofpbuf_set_size(struct ofpbuf *, uint32_t);

void * ofpbuf_resize_l2(struct ofpbuf *, int increment);
void * ofpbuf_resize_l2_5(struct ofpbuf *, int increment);
static inline void * ofpbuf_l2(const struct ofpbuf *);
static inline void ofpbuf_set_frame(struct ofpbuf *, void *);
static inline uint8_t ofpbuf_l2_pad_size(const struct ofpbuf *);
static inline void ofpbuf_set_l2_pad_size(struct ofpbuf *, uint8_t);
static inline void * ofpbuf_l2_5(const struct ofpbuf *);
static inline void ofpbuf_set_l2_5(struct ofpbuf *, void *);
static inline void * ofpbuf_l3(const struct ofpbuf *);
static inline void ofpbuf_set_l3(struct ofpbuf *, void *);
static inline void * ofpbuf_l4(const struct ofpbuf *);
static inline void ofpbuf_set_l4(struct ofpbuf *, void *);
static inline size_t ofpbuf_l4_size(const struct ofpbuf *);
static inline const void *ofpbuf_get_tcp_payload(const struct ofpbuf *);
static inline const void *ofpbuf_get_udp_payload(const struct ofpbuf *);
static inline const void *ofpbuf_get_sctp_payload(const struct ofpbuf *);
static inline const void *ofpbuf_get_icmp_payload(const struct ofpbuf *);

void ofpbuf_use(struct ofpbuf *, void *, size_t);
void ofpbuf_use_stack(struct ofpbuf *, void *, size_t);
void ofpbuf_use_stub(struct ofpbuf *, void *, size_t);
void ofpbuf_use_const(struct ofpbuf *, const void *, size_t);

void ofpbuf_init_dpdk(struct ofpbuf *b, size_t allocated);

void ofpbuf_init(struct ofpbuf *, size_t);
void ofpbuf_uninit(struct ofpbuf *);
static inline void *ofpbuf_get_uninit_pointer(struct ofpbuf *);
void ofpbuf_reinit(struct ofpbuf *, size_t);

struct ofpbuf *ofpbuf_new(size_t);
struct ofpbuf *ofpbuf_new_with_headroom(size_t, size_t headroom);
struct ofpbuf *ofpbuf_clone(const struct ofpbuf *);
struct ofpbuf *ofpbuf_clone_with_headroom(const struct ofpbuf *,
                                          size_t headroom);
struct ofpbuf *ofpbuf_clone_data(const void *, size_t);
struct ofpbuf *ofpbuf_clone_data_with_headroom(const void *, size_t,
                                               size_t headroom);
static inline void ofpbuf_delete(struct ofpbuf *);

static inline void *ofpbuf_at(const struct ofpbuf *, size_t offset,
                              size_t size);
static inline void *ofpbuf_at_assert(const struct ofpbuf *, size_t offset,
                                     size_t size);
static inline void *ofpbuf_tail(const struct ofpbuf *);
static inline void *ofpbuf_end(const struct ofpbuf *);

void *ofpbuf_put_uninit(struct ofpbuf *, size_t);
void *ofpbuf_put_zeros(struct ofpbuf *, size_t);
void *ofpbuf_put(struct ofpbuf *, const void *, size_t);
char *ofpbuf_put_hex(struct ofpbuf *, const char *s, size_t *n);
void ofpbuf_reserve(struct ofpbuf *, size_t);
void ofpbuf_reserve_with_tailroom(struct ofpbuf *b, size_t headroom,
                                  size_t tailroom);
void *ofpbuf_push_uninit(struct ofpbuf *b, size_t);
void *ofpbuf_push_zeros(struct ofpbuf *, size_t);
void *ofpbuf_push(struct ofpbuf *b, const void *, size_t);

static inline size_t ofpbuf_headroom(const struct ofpbuf *);
static inline size_t ofpbuf_tailroom(const struct ofpbuf *);
void ofpbuf_prealloc_headroom(struct ofpbuf *, size_t);
void ofpbuf_prealloc_tailroom(struct ofpbuf *, size_t);
void ofpbuf_trim(struct ofpbuf *);
void ofpbuf_padto(struct ofpbuf *, size_t);
void ofpbuf_shift(struct ofpbuf *, int);

static inline void ofpbuf_clear(struct ofpbuf *);
static inline void *ofpbuf_pull(struct ofpbuf *, size_t);
static inline void *ofpbuf_try_pull(struct ofpbuf *, size_t);

void *ofpbuf_steal_data(struct ofpbuf *);

char *ofpbuf_to_string(const struct ofpbuf *, size_t maxbytes);
static inline struct ofpbuf *ofpbuf_from_list(const struct ovs_list *);
void ofpbuf_list_delete(struct ovs_list *);
static inline bool ofpbuf_equal(const struct ofpbuf *, const struct ofpbuf *);


/* Returns a pointer that may be passed to free() to accomplish the same thing
 * as ofpbuf_uninit(b).  The return value is a null pointer if ofpbuf_uninit()
 * would not free any memory. */
static inline void *ofpbuf_get_uninit_pointer(struct ofpbuf *b)
{
    /* XXX: If 'source' is OFPBUF_DPDK memory gets leaked! */
    return b && b->source == OFPBUF_MALLOC ? ofpbuf_base(b) : NULL;
}

/* Frees memory that 'b' points to, as well as 'b' itself. */
static inline void ofpbuf_delete(struct ofpbuf *b)
{
    if (b) {
        if (b->source == OFPBUF_DPDK) {
            /* If this ofpbuf was allocated by DPDK it must have been
             * created as a dpif_packet */
            free_dpdk_buf((struct dpif_packet*) b);
            return;
        }

        ofpbuf_uninit(b);
        free(b);
    }
}

/* If 'b' contains at least 'offset + size' bytes of data, returns a pointer to
 * byte 'offset'.  Otherwise, returns a null pointer. */
static inline void *ofpbuf_at(const struct ofpbuf *b, size_t offset,
                              size_t size)
{
    return offset + size <= ofpbuf_size(b) ? (char *) ofpbuf_data(b) + offset : NULL;
}

/* Returns a pointer to byte 'offset' in 'b', which must contain at least
 * 'offset + size' bytes of data. */
static inline void *ofpbuf_at_assert(const struct ofpbuf *b, size_t offset,
                                     size_t size)
{
    ovs_assert(offset + size <= ofpbuf_size(b));
    return ((char *) ofpbuf_data(b)) + offset;
}

/* Returns a pointer to byte following the last byte of data in use in 'b'. */
static inline void *ofpbuf_tail(const struct ofpbuf *b)
{
    return (char *) ofpbuf_data(b) + ofpbuf_size(b);
}

/* Returns a pointer to byte following the last byte allocated for use (but
 * not necessarily in use) in 'b'. */
static inline void *ofpbuf_end(const struct ofpbuf *b)
{
    return (char *) ofpbuf_base(b) + b->allocated;
}

/* Returns the number of bytes of headroom in 'b', that is, the number of bytes
 * of unused space in ofpbuf 'b' before the data that is in use.  (Most
 * commonly, the data in a ofpbuf is at its beginning, and thus the ofpbuf's
 * headroom is 0.) */
static inline size_t ofpbuf_headroom(const struct ofpbuf *b)
{
    return (char*)ofpbuf_data(b) - (char*)ofpbuf_base(b);
}

/* Returns the number of bytes that may be appended to the tail end of ofpbuf
 * 'b' before the ofpbuf must be reallocated. */
static inline size_t ofpbuf_tailroom(const struct ofpbuf *b)
{
    return (char*)ofpbuf_end(b) - (char*)ofpbuf_tail(b);
}

/* Clears any data from 'b'. */
static inline void ofpbuf_clear(struct ofpbuf *b)
{
    ofpbuf_set_data(b, ofpbuf_base(b));
    ofpbuf_set_size(b, 0);
}

/* Removes 'size' bytes from the head end of 'b', which must contain at least
 * 'size' bytes of data.  Returns the first byte of data removed. */
static inline void *ofpbuf_pull(struct ofpbuf *b, size_t size)
{
    void *data = ofpbuf_data(b);
    ovs_assert(ofpbuf_size(b) - ofpbuf_l2_pad_size(b) >= size);
    ofpbuf_set_data(b, (char*)ofpbuf_data(b) + size);
    ofpbuf_set_size(b, ofpbuf_size(b) - size);
    return data;
}

/* If 'b' has at least 'size' bytes of data, removes that many bytes from the
 * head end of 'b' and returns the first byte removed.  Otherwise, returns a
 * null pointer without modifying 'b'. */
static inline void *ofpbuf_try_pull(struct ofpbuf *b, size_t size)
{
    return ofpbuf_size(b) - ofpbuf_l2_pad_size(b) >= size
        ? ofpbuf_pull(b, size) : NULL;
}

static inline struct ofpbuf *ofpbuf_from_list(const struct ovs_list *list)
{
    return CONTAINER_OF(list, struct ofpbuf, list_node);
}

static inline bool ofpbuf_equal(const struct ofpbuf *a, const struct ofpbuf *b)
{
    return ofpbuf_size(a) == ofpbuf_size(b) &&
           memcmp(ofpbuf_data(a), ofpbuf_data(b), ofpbuf_size(a)) == 0;
}

/* Get the start if the Ethernet frame.  'l3_ofs' marks the end of the l2
 * headers, so return NULL if it is not set. */
static inline void * ofpbuf_l2(const struct ofpbuf *b)
{
    return (b->l3_ofs != UINT16_MAX) ? b->frame : NULL;
}

/* Sets the packet frame start pointer and resets all layer offsets.
 * l3 offset must be set before 'l2' can be retrieved. */
static inline void ofpbuf_set_frame(struct ofpbuf *b, void *packet)
{
    b->frame = packet;
    b->l2_pad_size = 0;
    b->l2_5_ofs = UINT16_MAX;
    b->l3_ofs = UINT16_MAX;
    b->l4_ofs = UINT16_MAX;
}

static inline uint8_t ofpbuf_l2_pad_size(const struct ofpbuf *b)
{
    return b->l2_pad_size;
}

static inline void ofpbuf_set_l2_pad_size(struct ofpbuf *b, uint8_t pad_size)
{
    ovs_assert(pad_size <= ofpbuf_size(b));
    b->l2_pad_size = pad_size;
}

static inline void * ofpbuf_l2_5(const struct ofpbuf *b)
{
    return b->l2_5_ofs != UINT16_MAX ? (char *)b->frame + b->l2_5_ofs : NULL;
}

static inline void ofpbuf_set_l2_5(struct ofpbuf *b, void *l2_5)
{
    b->l2_5_ofs = l2_5 ? (char *)l2_5 - (char *)b->frame : UINT16_MAX;
}

static inline void * ofpbuf_l3(const struct ofpbuf *b)
{
    return b->l3_ofs != UINT16_MAX ? (char *)b->frame + b->l3_ofs : NULL;
}

static inline void ofpbuf_set_l3(struct ofpbuf *b, void *l3)
{
    b->l3_ofs = l3 ? (char *)l3 - (char *)b->frame : UINT16_MAX;
}

static inline void * ofpbuf_l4(const struct ofpbuf *b)
{
    return b->l4_ofs != UINT16_MAX ? (char *)b->frame + b->l4_ofs : NULL;
}

static inline void ofpbuf_set_l4(struct ofpbuf *b, void *l4)
{
    b->l4_ofs = l4 ? (char *)l4 - (char *)b->frame : UINT16_MAX;
}

static inline size_t ofpbuf_l4_size(const struct ofpbuf *b)
{
    return b->l4_ofs != UINT16_MAX
        ? (const char *)ofpbuf_tail(b) - (const char *)ofpbuf_l4(b)
        - ofpbuf_l2_pad_size(b)
        : 0;
}

static inline const void *ofpbuf_get_tcp_payload(const struct ofpbuf *b)
{
    size_t l4_size = ofpbuf_l4_size(b);

    if (OVS_LIKELY(l4_size >= TCP_HEADER_LEN)) {
        struct tcp_header *tcp = ofpbuf_l4(b);
        int tcp_len = TCP_OFFSET(tcp->tcp_ctl) * 4;

        if (OVS_LIKELY(tcp_len >= TCP_HEADER_LEN && tcp_len <= l4_size)) {
            return (const char *)tcp + tcp_len;
        }
    }
    return NULL;
}

static inline const void *ofpbuf_get_udp_payload(const struct ofpbuf *b)
{
    return OVS_LIKELY(ofpbuf_l4_size(b) >= UDP_HEADER_LEN)
        ? (const char *)ofpbuf_l4(b) + UDP_HEADER_LEN : NULL;
}

static inline const void *ofpbuf_get_sctp_payload(const struct ofpbuf *b)
{
    return OVS_LIKELY(ofpbuf_l4_size(b) >= SCTP_HEADER_LEN)
        ? (const char *)ofpbuf_l4(b) + SCTP_HEADER_LEN : NULL;
}

static inline const void *ofpbuf_get_icmp_payload(const struct ofpbuf *b)
{
    return OVS_LIKELY(ofpbuf_l4_size(b) >= ICMP_HEADER_LEN)
        ? (const char *)ofpbuf_l4(b) + ICMP_HEADER_LEN : NULL;
}

#ifdef DPDK_NETDEV
BUILD_ASSERT_DECL(offsetof(struct ofpbuf, mbuf) == 0);

static inline void * ofpbuf_data(const struct ofpbuf *b)
{
    return b->mbuf.pkt.data;
}

static inline void ofpbuf_set_data(struct ofpbuf *b, void *d)
{
    b->mbuf.pkt.data = d;
}

static inline void * ofpbuf_base(const struct ofpbuf *b)
{
    return b->mbuf.buf_addr;
}

static inline void ofpbuf_set_base(struct ofpbuf *b, void *d)
{
    b->mbuf.buf_addr = d;
}

static inline uint32_t ofpbuf_size(const struct ofpbuf *b)
{
    return b->mbuf.pkt.pkt_len;
}

static inline void ofpbuf_set_size(struct ofpbuf *b, uint32_t v)
{
    b->mbuf.pkt.data_len = v;    /* Current seg length. */
    b->mbuf.pkt.pkt_len = v;     /* Total length of all segments linked to
                                  * this segment. */
}

#else
static inline void * ofpbuf_data(const struct ofpbuf *b)
{
    return b->data_;
}

static inline void ofpbuf_set_data(struct ofpbuf *b, void *d)
{
    b->data_ = d;
}

static inline void * ofpbuf_base(const struct ofpbuf *b)
{
    return b->base_;
}

static inline void ofpbuf_set_base(struct ofpbuf *b, void *d)
{
    b->base_ = d;
}

static inline uint32_t ofpbuf_size(const struct ofpbuf *b)
{
    return b->size_;
}

static inline void ofpbuf_set_size(struct ofpbuf *b, uint32_t v)
{
    b->size_ = v;
}
#endif

static inline void ofpbuf_reset_packet(struct ofpbuf *b, int off)
{
    ofpbuf_set_size(b, ofpbuf_size(b) - off);
    ofpbuf_set_data(b, (void *) ((unsigned char *) b->frame + off));
    b->frame = NULL;
    b->l2_5_ofs = b->l3_ofs = b->l4_ofs = UINT16_MAX;
}

#ifdef  __cplusplus
}
#endif

#endif /* ofpbuf.h */