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// SPDX-FileCopyrightText: 2024 Lizzy Fleckenstein <lizzy@vlhl.dev>
//
// SPDX-License-Identifier: AGPL-3.0-or-later
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <poll.h>
#include <errno.h>
#include "peer.h"
void peer_init(peer *p, int socket)
{
p->socket = socket;
p->disco = false;
p->in.header = true;
p->in.len = 0;
p->in.promised = 0;
p->in.buffer = malloc(PEER_INBUFFER_SIZE);
p->out.cursor = 0;
p->out.avail = 0;
p->out.buffer = malloc(PEER_OUTBUFFER_SIZE);
}
void peer_free(peer *p)
{
close(p->socket);
free(p->in.buffer);
free(p->out.buffer);
}
// in
static void next_in(peer *p, bool header, size_t len)
{
p->in.header = header;
p->in.len = 0;
p->in.buffer = malloc(p->in.promised = len);
}
static bool peer_in_ready(peer *p)
{
ssize_t got = read(p->socket, p->in.buffer + p->in.len, p->in.promised - p->in.len);
if (got < 0) {
switch (errno) {
case ECONNRESET:
p->disco = true;
return true;
case EINTR:
return peer_in_ready(p); // retry
default:
perror("read");
return false;
}
}
p->in.len += got;
if (p->in.len == p->in.promised && p->in.len != 0) {
if (!p->in.header)
return true;
size_t len = *(pkt_header *) p->in.buffer;
if (len > PEER_INBUFFER_SIZE)
// TODO: figure out what to do if packet too large (disconnect?)
next_in(p, true, sizeof(pkt_header));
else
next_in(p, false, len);
}
return false;
}
// out
static void send_raw(peer *p, void *data, size_t len)
{
memcpy(p->out.buffer + p->out.cursor + p->out.avail, data, len);
p->out.avail += len;
}
static bool out_space(peer *p, size_t len)
{
if (len + p->out.avail > PEER_OUTBUFFER_SIZE)
return false;
if (p->out.cursor + p->out.avail + len > PEER_OUTBUFFER_SIZE) {
memmove(p->out.buffer, p->out.buffer + p->out.cursor, p->out.avail);
p->out.cursor = 0;
}
return true;
}
bool peer_send(peer *p, void *data, size_t len)
{
if (len > PEER_INBUFFER_SIZE)
return false;
pkt_header hdr = (pkt_header) len;
if (!out_space(p, sizeof hdr + len))
return false;
send_raw(p, &hdr, sizeof hdr);
send_raw(p, data, len);
return true;
}
static bool peer_out_ready(peer *p)
{
ssize_t written = write(p->socket, p->out.buffer + p->out.cursor, p->out.avail);
if (written < 0) {
switch (errno) {
case ECONNRESET:
p->disco = true;
return true;
case EINTR:
return peer_out_ready(p);
default:
perror("write");
return false;
}
}
p->out.avail -= written;
if (p->out.avail == 0)
p->out.cursor = 0;
return false;
}
// poll
struct pollfd peer_prepare(peer *p)
{
struct pollfd pfd = {0};
pfd.fd = p->socket;
if (p->in.len == p->in.promised)
next_in(p, true, sizeof(pkt_header));
pfd.events = POLLIN | (p->out.avail ? POLLOUT : 0);
return pfd;
}
bool peer_ready(peer *p, struct pollfd pfd)
{
bool x = false;
if (pfd.revents & (POLLHUP | POLLERR))
p->disco = true;
if (pfd.revents & POLLIN)
x = x || peer_in_ready(p);
if (pfd.revents & POLLOUT)
x = x || peer_out_ready(p);
return x;
}
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