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/*
* linux/net/sunrpc/socklib.c
*
* Common socket helper routines for RPC client and server
*
* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
*/
#include <linux/types.h>
#include <linux/pagemap.h>
#include <linux/udp.h>
#include <linux/sunrpc/xdr.h>
/**
* skb_read_bits - copy some data bits from skb to internal buffer
* @desc: sk_buff copy helper
* @to: copy destination
* @len: number of bytes to copy
*
* Possibly called several times to iterate over an sk_buff and copy
* data out of it.
*/
static size_t skb_read_bits(skb_reader_t *desc, void *to, size_t len)
{
if (len > desc->count)
len = desc->count;
if (skb_copy_bits(desc->skb, desc->offset, to, len))
return 0;
desc->count -= len;
desc->offset += len;
return len;
}
/**
* skb_read_and_csum_bits - copy and checksum from skb to buffer
* @desc: sk_buff copy helper
* @to: copy destination
* @len: number of bytes to copy
*
* Same as skb_read_bits, but calculate a checksum at the same time.
*/
static size_t skb_read_and_csum_bits(skb_reader_t *desc, void *to, size_t len)
{
unsigned int csum2, pos;
if (len > desc->count)
len = desc->count;
pos = desc->offset;
csum2 = skb_copy_and_csum_bits(desc->skb, pos, to, len, 0);
desc->csum = csum_block_add(desc->csum, csum2, pos);
desc->count -= len;
desc->offset += len;
return len;
}
/**
* xdr_partial_copy_from_skb - copy data out of an skb
* @xdr: target XDR buffer
* @base: starting offset
* @desc: sk_buff copy helper
* @copy_actor: virtual method for copying data
*
*/
ssize_t xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base, skb_reader_t *desc, skb_read_actor_t copy_actor)
{
struct page **ppage = xdr->pages;
unsigned int len, pglen = xdr->page_len;
ssize_t copied = 0;
int ret;
len = xdr->head[0].iov_len;
if (base < len) {
len -= base;
ret = copy_actor(desc, (char *)xdr->head[0].iov_base + base, len);
copied += ret;
if (ret != len || !desc->count)
goto out;
base = 0;
} else
base -= len;
if (unlikely(pglen == 0))
goto copy_tail;
if (unlikely(base >= pglen)) {
base -= pglen;
goto copy_tail;
}
if (base || xdr->page_base) {
pglen -= base;
base += xdr->page_base;
ppage += base >> PAGE_CACHE_SHIFT;
base &= ~PAGE_CACHE_MASK;
}
do {
char *kaddr;
/* ACL likes to be lazy in allocating pages - ACLs
* are small by default but can get huge. */
if (unlikely(*ppage == NULL)) {
*ppage = alloc_page(GFP_ATOMIC);
if (unlikely(*ppage == NULL)) {
if (copied == 0)
copied = -ENOMEM;
goto out;
}
}
len = PAGE_CACHE_SIZE;
kaddr = kmap_atomic(*ppage, KM_SKB_SUNRPC_DATA);
if (base) {
len -= base;
if (pglen < len)
len = pglen;
ret = copy_actor(desc, kaddr + base, len);
base = 0;
} else {
if (pglen < len)
len = pglen;
ret = copy_actor(desc, kaddr, len);
}
flush_dcache_page(*ppage);
kunmap_atomic(kaddr, KM_SKB_SUNRPC_DATA);
copied += ret;
if (ret != len || !desc->count)
goto out;
ppage++;
} while ((pglen -= len) != 0);
copy_tail:
len = xdr->tail[0].iov_len;
if (base < len)
copied += copy_actor(desc, (char *)xdr->tail[0].iov_base + base, len - base);
out:
return copied;
}
/**
* csum_partial_copy_to_xdr - checksum and copy data
* @xdr: target XDR buffer
* @skb: source skb
*
* We have set things up such that we perform the checksum of the UDP
* packet in parallel with the copies into the RPC client iovec. -DaveM
*/
int csum_partial_copy_to_xdr(struct xdr_buf *xdr, struct sk_buff *skb)
{
skb_reader_t desc;
desc.skb = skb;
desc.offset = sizeof(struct udphdr);
desc.count = skb->len - desc.offset;
if (skb->ip_summed == CHECKSUM_UNNECESSARY)
goto no_checksum;
desc.csum = csum_partial(skb->data, desc.offset, skb->csum);
if (xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_and_csum_bits) < 0)
return -1;
if (desc.offset != skb->len) {
unsigned int csum2;
csum2 = skb_checksum(skb, desc.offset, skb->len - desc.offset, 0);
desc.csum = csum_block_add(desc.csum, csum2, desc.offset);
}
if (desc.count)
return -1;
if ((unsigned short)csum_fold(desc.csum))
return -1;
return 0;
no_checksum:
if (xdr_partial_copy_from_skb(xdr, 0, &desc, skb_read_bits) < 0)
return -1;
if (desc.count)
return -1;
return 0;
}
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