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This commit is contained in:
Francesco Cozzuto
2023-04-21 09:46:44 +02:00
parent 092ba2d1ad
commit 43ee04a2db
9 changed files with 510 additions and 47 deletions
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src/tcp.c
+83 -32
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@@ -10,12 +10,6 @@
#define TCP_DEBUG_LOG(...)
#endif
static int tcp_send(tcp_state_t *tcp_state, ip_address_t ip,
const void *src, size_t len)
{
return tcp_state->callbacks.send(tcp_state->callbacks.data, ip, src, len);
}
void tcp_init(tcp_state_t *tcp_state, ip_address_t ip, tcp_callbacks_t callbacks)
{
tcp_state->ip = ip;
@@ -47,6 +41,10 @@ void tcp_seconds_passed(tcp_state_t *state, size_t seconds)
(void) seconds;
}
typedef enum {
TCP_CONNECTION_
} tcp_connection_state;
static tcp_connection_t*
connection_create_waiting_for_ack(tcp_listener_t *listener,
uint32_t seq_no, uint32_t ack_no,
@@ -133,7 +131,9 @@ static tcp_connection_t *find_connection(tcp_connection_t *list, ip_address_t pe
return NULL;
}
static connection_state_t find_connection_associated_to(tcp_listener_t *listener, ip_address_t peer_ip, uint16_t peer_port, tcp_connection_t **connection)
static connection_state_t
find_connection_associated_to(tcp_listener_t *listener, ip_address_t peer_ip,
uint16_t peer_port, tcp_connection_t **connection)
{
tcp_connection_t *connection2 = find_connection(listener->connections, peer_ip, peer_port);
if (connection2) {
@@ -175,25 +175,21 @@ typedef struct {
} tcp_pseudoheader_t;
static uint16_t
calculate_checksum_tcp(const void *a, const void *b,
size_t a_len, size_t b_len)
calculate_checksum(const slice_list_t *slices, size_t num_slices)
{
assert((a_len & 1) == 0
&& (b_len & 1) == 0);
const uint16_t *a2 = a;
const uint16_t *b2 = b;
uint32_t sum = 0xffff;
for (size_t i = 0; i < a_len/2; i++) {
sum += ntohs(a2[i]);
if (sum > 0xffff)
sum -= 0xffff;
}
for (size_t i = 0; i < b_len/2; i++) {
sum += ntohs(b2[i]);
if (sum > 0xffff)
sum -= 0xffff;
for (size_t slice_idx = 0; slice_idx < num_slices; slice_idx++) {
assert((slices[slice_idx].len & 1) == 0);
const uint16_t *src = slices[slice_idx].src;
const size_t len = slices[slice_idx].len;
for (size_t i = 0; i < len/2; i++) {
sum += ntohs(src[i]);
if (sum > 0xffff)
sum -= 0xffff;
}
}
return htons(~sum);
@@ -252,7 +248,7 @@ static void emit_segment(tcp_connection_t *connection, bool ack, bool syn, size_
//if (payload_being_sent > 0)
// seq_no++;
connection->out_header = (tcp_segment_t) {
tcp_segment_t header = {
.src_port = htons(listener->port),
.dst_port = htons(connection->peer_port),
.flags = flags,
@@ -273,10 +269,17 @@ static void emit_segment(tcp_connection_t *connection, bool ack, bool syn, size_
.tcp_length = htons(total_segment_size),
};
connection->out_header.checksum = calculate_checksum_tcp(&pseudo_header, &connection->out_header, sizeof(pseudo_header), total_segment_size);
header.checksum = calculate_checksum((slice_list_t[]) {
{&pseudo_header, sizeof(tcp_pseudoheader_t)},
{&header, sizeof(tcp_segment_t)},
{connection->out_buffer, connection->snd_wnd},
}, 3);
int result = state->callbacks.send(state->callbacks.data, connection->peer_ip, (slice_list_t[]) {
{&header, sizeof(tcp_segment_t)},
{connection->out_buffer, payload_being_sent},
}, 2);
int result = tcp_send(state, connection->peer_ip, &connection->out_header, total_segment_size);
if (result < 0) {
// It wasn't possible to send out bytes. We'll try again later!
} else {
@@ -449,6 +452,7 @@ tcp_listener_create(tcp_state_t *state, uint16_t port, void *callback_data,
listener->port = port;
listener->connections = NULL;
listener->connections_waiting_for_ack = NULL;
listener->connections_waiting_for_fin = NULL;
listener->connections_waiting_for_accept_head = NULL;
listener->connections_waiting_for_accept_tail = NULL;
listener->callback_data = callback_data;
@@ -533,13 +537,18 @@ void tcp_connection_destroy(tcp_connection_t *connection)
// NOTE: This can only be called when the
// connection was accepted.
// Make sure the connection was first finished
// by being moved from the idle list to the
// waiting-for-fin list.
tcp_connection_finish(connection);
tcp_listener_t *listener = connection->listener;
// Pop connection from the idle connection list
// Pop connection from the waiting-for-fin list
if (connection->prev)
connection->prev->next = connection->next;
else
listener->connections = connection->next;
listener->connections_waiting_for_fin = connection->next;
// Push it into the free connection list
tcp_state_t *state = listener->state;
@@ -583,7 +592,49 @@ append_to_output_buffer(tcp_connection_t *connection,
size_t tcp_connection_send(tcp_connection_t *connection, const void *src, size_t len)
{
size_t num = append_to_output_buffer(connection, src, len);
emit_segment(connection, false, false, SIZE_MAX);
size_t num;
if (connection->read_only)
num = 0;
else {
num = append_to_output_buffer(connection, src, len);
emit_segment(connection, false, false, SIZE_MAX);
}
return num;
}
void tcp_connection_finish(tcp_connection_t *connection)
{
if (!connection->read_only) {
// Move connection from idle list to
// waiting-for-fin list
tcp_listener_t *listener = connection->listener;
// Pop it from the idle list
{
if (connection->prev)
connection->prev->next = connection->next;
else
listener->connections = connection->next;
if (connection->next)
connection->next->prev = connection->prev;
connection->prev = NULL;
connection->next = NULL;
}
#warning "The FIN segment should be sent here"
// Push it to the waiting-for-fin list
{
connection->prev = NULL;
connection->next = listener->connections_waiting_for_fin;
listener->connections_waiting_for_fin = connection;
}
// Now mark the connection as read-only
connection->read_only = true;
}
}