Ben Pfaff
60a87c9b00
We want to allow multiple OpenFlow connections to a switch, so that dpctl and other management tools can also connect to a switch that is connecte to the controller. These tools will want to fetch the information in the data_hello message, but currently this can only be done by sending a control_hello message, which changes the switch configuration state. So breaking the hello messages up into multiple different messages, only some of which affect configuration state, cures the problem. Also, clean up the kernel datapath a bit, by adding helper functions for allocating and resizing Generic Netlink messages that encapsulate OpenFlow messages.
243 lines
6.8 KiB
C
243 lines
6.8 KiB
C
/* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
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* Junior University
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*
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* We are making the OpenFlow specification and associated documentation
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* (Software) available for public use and benefit with the expectation
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* that others will use, modify and enhance the Software and contribute
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* those enhancements back to the community. However, since we would
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* like to make the Software available for broadest use, with as few
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* restrictions as possible permission is hereby granted, free of
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* charge, to any person obtaining a copy of this Software to deal in
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* the Software under the copyrights without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* The name and trademarks of copyright holder(s) may NOT be used in
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* advertising or publicity pertaining to the Software or any
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* derivatives without specific, written prior permission.
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*/
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#include "buffer.h"
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#include <assert.h>
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#include <stdlib.h>
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#include <string.h>
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#include "util.h"
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/* Initializes 'b' as an empty buffer that contains the 'allocated' bytes of
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* memory starting at 'base'.
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*
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* 'base' should ordinarily be the first byte of a region obtained from
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* malloc(), but in circumstances where it can be guaranteed that 'b' will
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* never need to be expanded or freed, it can be a pointer into arbitrary
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* memory. */
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void
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buffer_use(struct buffer *b, void *base, size_t allocated)
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{
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b->base = b->data = base;
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b->allocated = allocated;
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b->size = 0;
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b->l2 = b->l3 = b->l4 = NULL;
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b->next = NULL;
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}
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/* Initializes 'b' as a buffer with an initial capacity of 'size' bytes. */
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void
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buffer_init(struct buffer *b, size_t size)
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{
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buffer_use(b, size ? xmalloc(size) : NULL, size);
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}
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/* Frees memory that 'b' points to. */
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void
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buffer_uninit(struct buffer *b)
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{
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if (b) {
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free(b->base);
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}
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}
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/* Frees memory that 'b' points to and allocates a new buffer */
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void
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buffer_reinit(struct buffer *b, size_t size)
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{
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buffer_uninit(b);
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buffer_init(b, size);
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}
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/* Creates and returns a new buffer with an initial capacity of 'size'
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* bytes. */
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struct buffer *
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buffer_new(size_t size)
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{
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struct buffer *b = xmalloc(sizeof *b);
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buffer_init(b, size);
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return b;
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}
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struct buffer *
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buffer_clone(const struct buffer *buffer)
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{
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/* FIXME: reference counting. */
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struct buffer *b = buffer_new(buffer->size);
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buffer_put(b, buffer->data, buffer->size);
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return b;
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}
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/* Frees memory that 'b' points to, as well as 'b' itself. */
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void
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buffer_delete(struct buffer *b)
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{
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if (b) {
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buffer_uninit(b);
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free(b);
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}
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}
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/* Returns the number of bytes of headroom in 'b', that is, the number of bytes
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* of unused space in buffer 'b' before the data that is in use. (Most
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* commonly, the data in a buffer is at its beginning, and thus the buffer's
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* headroom is 0.) */
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size_t
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buffer_headroom(struct buffer *b)
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{
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return b->data - b->base;
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}
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/* Returns the number of bytes that may be appended to the tail end of buffer
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* 'b' before the buffer must be reallocated. */
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size_t
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buffer_tailroom(struct buffer *b)
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{
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return buffer_end(b) - buffer_tail(b);
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}
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/* Ensures that 'b' has room for at least 'size' bytes at its tail end,
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* reallocating and copying its data if necessary. */
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void
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buffer_reserve_tailroom(struct buffer *b, size_t size)
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{
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if (size > buffer_tailroom(b)) {
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size_t new_allocated = b->allocated + MAX(size, 64);
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void *new_base = xmalloc(new_allocated);
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uintptr_t base_delta = new_base - b->base;
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memcpy(new_base, b->base, b->allocated);
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free(b->base);
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b->base = new_base;
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b->allocated = new_allocated;
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b->data += base_delta;
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if (b->l2) {
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b->l2 += base_delta;
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}
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if (b->l3) {
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b->l3 += base_delta;
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}
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if (b->l4) {
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b->l4 += base_delta;
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}
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}
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}
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void
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buffer_reserve_headroom(struct buffer *b, size_t size)
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{
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assert(size <= buffer_headroom(b));
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}
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/* Appends 'size' bytes of data to the tail end of 'b', reallocating and
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* copying its data if necessary. Returns a pointer to the first byte of the
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* new data, which is left uninitialized. */
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void *
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buffer_put_uninit(struct buffer *b, size_t size)
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{
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void *p;
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buffer_reserve_tailroom(b, size);
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p = buffer_tail(b);
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b->size += size;
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return p;
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}
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/* Appends the 'size' bytes of data in 'p' to the tail end of 'b'. Data in 'b'
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* is reallocated and copied if necessary. Returns a pointer to the first
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* byte of the data's location in the buffer. */
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void *
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buffer_put(struct buffer *b, const void *p, size_t size)
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{
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void *dst = buffer_put_uninit(b, size);
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memcpy(dst, p, size);
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return dst;
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}
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void *
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buffer_push_uninit(struct buffer *b, size_t size)
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{
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buffer_reserve_headroom(b, size);
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b->data -= size;
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b->size += size;
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return b->data;
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}
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/* If 'b' contains at least 'offset + size' bytes of data, returns a pointer to
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* byte 'offset'. Otherwise, returns a null pointers. */
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void *
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buffer_at(const struct buffer *b, size_t offset, size_t size)
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{
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return offset + size <= b->size ? (char *) b->data + offset : NULL;
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}
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/* Returns a pointer to byte 'offset' in 'b', which must contain at least
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* 'offset + size' bytes of data. */
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void *
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buffer_at_assert(const struct buffer *b, size_t offset, size_t size)
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{
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assert(offset + size <= b->size);
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return ((char *) b->data) + offset;
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}
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/* Returns the byte following the last byte of data in use in 'b'. */
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void *
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buffer_tail(const struct buffer *b)
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{
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return (char *) b->data + b->size;
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}
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/* Returns the byte following the last byte allocated for use (but not
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* necessarily in use) by 'b'. */
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void *
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buffer_end(const struct buffer *b)
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{
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return (char *) b->base + b->allocated;
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}
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/* Clears any data from 'b'. */
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void
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buffer_clear(struct buffer *b)
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{
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b->data = b->base;
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b->size = 0;
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}
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/* Removes 'size' bytes from the head end of 'b', which must contain at least
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* 'size' bytes of data. */
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void
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buffer_pull(struct buffer *b, size_t size)
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{
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assert(b->size >= size);
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b->data += size;
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b->size -= size;
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}
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