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/**
* @file tcp_netstring.c TCP netstring framing
*
* Copyright (C) 2018 46 Labs LLC
*/
#include <math.h>
#include <string.h>
#include <re_types.h>
#include <re_fmt.h>
#include <re_mem.h>
#include <re_mbuf.h>
#include <re_tcp.h>
#include <re_net.h>
#include "tcp_netstring.h"
#include "netstring/netstring.h"
#define DEBUG_MODULE "tcp_netstring"
#define DEBUG_LEVEL 5
#include <re_dbg.h>
struct netstring {
struct tcp_conn *tc;
struct tcp_helper *th;
struct mbuf *mb;
netstring_frame_h *frameh;
void *arg;
uint64_t n_tx;
uint64_t n_rx;
};
/* responsible for adding the netstring header
- assumes that the sent MBUF contains a complete packet
*/
static bool netstring_send_handler(int *err, struct mbuf *mb, void *arg)
{
struct netstring *netstring = arg;
size_t num_len;
char num_str[32];
if (mb->pos < NETSTRING_HEADER_SIZE) {
DEBUG_WARNING("send: not enough space for netstring header\n");
*err = ENOMEM;
return true;
}
if (mbuf_get_left(mb) > NETSTRING_MAX_SIZE) {
DEBUG_WARNING("send: buffer exceeds max size\n");
*err = EMSGSIZE;
return true;
}
/* Build the netstring. */
if (mbuf_get_left(mb) == 0) {
mb->buf[0] = '0';
mb->buf[1] = ':';
mb->buf[2] = ',';
mb->end += 3;
return false;
}
re_snprintf(num_str, sizeof(num_str), "%zu", mbuf_get_left(mb));
num_len = strlen(num_str);
mb->pos = NETSTRING_HEADER_SIZE - (num_len + 1);
mbuf_write_mem(mb, (uint8_t*) num_str, num_len);
mb->pos = NETSTRING_HEADER_SIZE - (num_len + 1);
mb->buf[mb->pos + num_len] = ':';
mb->buf[mb->end] = ',';
mb->end += 1;
++netstring->n_tx;
return false;
}
static bool netstring_recv_handler(int *errp, struct mbuf *mbx, bool *estab,
void *arg)
{
struct netstring *netstring = arg;
int err = 0;
size_t pos = 0;
(void)estab;
/* handle re-assembly */
if (!netstring->mb) {
netstring->mb = mbuf_alloc(1024);
if (!netstring->mb) {
*errp = ENOMEM;
return true;
}
}
pos = netstring->mb->pos;
netstring->mb->pos = netstring->mb->end;
err = mbuf_write_mem(netstring->mb, mbuf_buf(mbx),
mbuf_get_left(mbx));
if (err)
goto out;
netstring->mb->pos = pos;
/* extract all NETSTRING-frames in the TCP-stream */
for (;;) {
size_t len, end;
struct mbuf mb;
if (mbuf_get_left(netstring->mb) < (3))
break;
err = netstring_read((char*)netstring->mb->buf,
netstring->mb->end,
(char**)&mb.buf, &len);
if (err) {
if (err == NETSTRING_ERROR_TOO_SHORT) {
DEBUG_INFO("receive: %s\n",
netstring_error_str(err));
}
else {
DEBUG_WARNING("receive: %s\n",
netstring_error_str(err));
netstring->mb = mem_deref(netstring->mb);
}
return false;
}
pos = netstring->mb->pos;
end = netstring->mb->end;
netstring->mb->end = pos + len;
++netstring->n_rx;
netstring->frameh(&mb, netstring->arg);
netstring->mb->pos = pos + netstring_buffer_size(len);
netstring->mb->end = end;
if (netstring->mb->pos >= netstring->mb->end) {
netstring->mb = mem_deref(netstring->mb);
break;
}
continue;
}
out:
if (err)
*errp = err;
return true; /* always handled */
}
static void destructor(void *arg)
{
struct netstring *netstring = arg;
mem_deref(netstring->th);
mem_deref(netstring->tc);
mem_deref(netstring->mb);
}
int netstring_insert(struct netstring **netstringp, struct tcp_conn *tc,
int layer, netstring_frame_h *frameh, void *arg)
{
struct netstring *netstring;
int err;
if (!netstringp || !tc || !frameh)
return EINVAL;
netstring = mem_zalloc(sizeof(*netstring), destructor);
if (!netstring)
return ENOMEM;
netstring->tc = mem_ref(tc);
err = tcp_register_helper(&netstring->th, tc, layer, NULL,
netstring_send_handler,
netstring_recv_handler, netstring);
if (err)
goto out;
netstring->frameh = frameh;
netstring->arg = arg;
out:
if (err)
mem_deref(netstring);
else
*netstringp = netstring;
return err;
}
int netstring_debug(struct re_printf *pf, const struct netstring *netstring)
{
if (!netstring)
return 0;
return re_hprintf(pf, "tx=%llu, rx=%llu",
netstring->n_tx, netstring->n_rx);
}
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