From 6543fecd7b45cc0232aa4148d0a7be125f4c49ea Mon Sep 17 00:00:00 2001
From: "Anna (navi) Figueiredo Gomes" <navi@vlhl.dev>
Date: Mon, 17 Jun 2024 00:03:18 +0200
Subject: *: restructure into subdirectoires and add REUSE

---
 src/peer.c | 156 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 src/peer.c

(limited to 'src/peer.c')

diff --git a/src/peer.c b/src/peer.c
new file mode 100644
index 0000000..f719622
--- /dev/null
+++ b/src/peer.c
@@ -0,0 +1,156 @@
+// 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, uint8_t *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, uint8_t *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, (uint8_t *) &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
+
+short peer_prepare(peer *p)
+{
+	if (p->in.len == p->in.promised)
+		next_in(p, true, sizeof(pkt_header));
+
+	return POLLIN | (p->out.avail ? POLLOUT : 0);
+}
+
+bool peer_ready(peer *p, short revents)
+{
+	bool x = false;
+
+	if (revents & POLLIN)
+		x = x || peer_in_ready(p);
+	if (revents & POLLOUT)
+		x = x || peer_out_ready(p);
+
+	return x;
+}
-- 
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