Fully implement sending
This commit is contained in:
Juhani Krekelä
parent
dab1565f31
commit
e7024d853b
115
ethermess.c
115
ethermess.c
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@ -24,6 +24,9 @@
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#define EM_PROTOCOL_VERSION 0
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#define EM_MESSAGE_MAX_LENGTH (1500 - 2 - 2 - 2)
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#define EM_STATUS_BROADCAST_TIME (5 * 60 * 1000 + 1000 * random_byte() / 64)
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#define EM_RETRANSMIT_TIME (1000 + random_byte() * 2)
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#define EM_MAX_RETRANSMIT 5
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#define EMT_SPEAK_VERSION 0
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#define EMT_STATUS_REQUEST 1
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@ -53,12 +56,14 @@ unsigned char own_nick[256];
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unsigned char own_nick_length = 0;
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struct timespec next_status_broadcast;
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enum message_send_states {IDLE, QUEUED, SENDING};
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enum message_send_states {IDLE, QUEUED, WAITING_MSGID, SENDING, WAITING_ACK};
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enum message_send_states own_message_send_state = IDLE;
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unsigned char own_message_destination_mac[6];
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unsigned char own_message[EM_MESSAGE_MAX_LENGTH];
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size_t own_message_length = 0;
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uint16_t own_message_msgid = 0;
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unsigned char retransmission_count = 0;
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struct timespec next_retransmission;
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struct msgid_cache_entry {
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unsigned char other_mac[6];
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@ -126,7 +131,7 @@ struct timespec ms_in_future(intmax_t ms) {
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#endif
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ts.tv_nsec += (ms % 1000) * 1000 * 1000;
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if (ts.tv_nsec >= 1000 * 1000 * 1000) {
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ts.tv_sec += -1;
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ts.tv_sec += 1;
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ts.tv_nsec -= 1000 * 1000 * 1000;
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}
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@ -447,8 +452,18 @@ void handle_msgid(const unsigned char source_mac[6], const unsigned char *data,
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cache_index = msgid_cache_add(source_mac);
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}
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msgid_cache[cache_index].next_send = msgid;
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msgid_cache[cache_index].know_send = true;
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if (msgid_cache[cache_index].know_send) {
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// There is sth in the cache, test whether we should update it
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uint16_t diff = msgid - msgid_cache[cache_index].next_send;
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if (diff < 0x8000) {
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// See the description in handle_message for what is going on
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msgid_cache[cache_index].next_send = msgid;
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}
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} else {
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// Nothing in the cache
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msgid_cache[cache_index].next_send = msgid;
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msgid_cache[cache_index].know_send = true;
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}
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char mac[18];
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format_mac(source_mac, mac);
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@ -505,7 +520,8 @@ void handle_message(const unsigned char source_mac[6], const unsigned char *data
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msgid_cache[cache_index].know_receive = true;
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}
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if (msgid_cache[cache_index].next_receive - msgid < 0x8000) {
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uint16_t diff = msgid - msgid_cache[cache_index].next_receive;
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if (diff < 0x8000) {
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// The msgid counter can wrap around, so a simple larger than
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// comparison will not work. Instead, we look at the distance
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// between the message's msgid and the one we're expecting to
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@ -571,7 +587,7 @@ void handle_ack(const unsigned char source_mac[6], const unsigned char *data, si
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err(1, "printf");
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}
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if (own_message_send_state == SENDING && msgid == own_message_msgid) {
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if (own_message_send_state == WAITING_ACK && msgid == own_message_msgid) {
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own_message_send_state = IDLE;
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}
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}
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@ -669,6 +685,8 @@ void eventloop(void) {
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pollfds[1].events = POLLIN;
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while (running) {
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int retransmit_wait_ms = INT_MAX;
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// (Attempt) to process a message send
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if (own_message_send_state == QUEUED) {
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// We need to have the correct msgid to be able to send
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@ -677,8 +695,11 @@ void eventloop(void) {
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if (cache_index == -1 || !msgid_cache[cache_index].know_send) {
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// We don't know what the msgid should be
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// -> ask the other side
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// TODO: Implement a timer
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send_msgid_request(own_message_destination_mac);
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// Wait around 1 to 1.5s before asking again
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next_retransmission = ms_in_future(EM_RETRANSMIT_TIME);
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retransmission_count = 0;
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own_message_send_state = WAITING_MSGID;
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} else {
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// It is in the cache
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own_message_msgid = msgid_cache[cache_index].next_send++;
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@ -686,18 +707,82 @@ void eventloop(void) {
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}
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}
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if (own_message_send_state == SENDING) {
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send_message();
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if (own_message_send_state == WAITING_MSGID) {
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ssize_t cache_index = msgid_cache_lookup(own_message_destination_mac);
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if (cache_index == -1 || !msgid_cache[cache_index].know_send) {
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// Still no msgid
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retransmit_wait_ms = wait_ms_until(next_retransmission);
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if (retransmit_wait_ms == 0 && retransmission_count < EM_MAX_RETRANSMIT) {
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// Time to resend
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send_msgid_request(own_message_destination_mac);
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// Wait around 1 to 1.5s before asking again
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next_retransmission = ms_in_future(EM_RETRANSMIT_TIME);
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retransmission_count++;
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} else if (retransmit_wait_ms == 0 && retransmission_count >= EM_MAX_RETRANSMIT) {
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// Time to give up
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own_message_send_state = IDLE;
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if (printf("Could not get msgid for message\n") == -1) {
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err(1, "printf");
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}
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if (fflush(stdout) == EOF) {
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err(1, "fflush");
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}
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}
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} else {
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// Found msgid
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own_message_msgid = msgid_cache[cache_index].next_send++;
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own_message_send_state = SENDING;
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}
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}
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// Figure out how many ms to wait
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int wait_ms = wait_ms_until(next_status_broadcast);
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if (wait_ms == 0) {
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if (own_message_send_state == SENDING) {
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send_message();
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// Wait around 1 to 1.5 before sending again
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next_retransmission = ms_in_future(EM_RETRANSMIT_TIME);
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retransmission_count = 0;
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own_message_send_state = WAITING_ACK;
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}
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if (own_message_send_state == WAITING_ACK) {
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retransmit_wait_ms = wait_ms_until(next_retransmission);
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if (retransmit_wait_ms == 0 && retransmission_count < EM_MAX_RETRANSMIT) {
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// Time to resend
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send_message();
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// Wait around 1 to 1.5 before sending again
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next_retransmission = ms_in_future(EM_RETRANSMIT_TIME);
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retransmission_count++;
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} else if (retransmit_wait_ms == 0 && retransmission_count >= EM_MAX_RETRANSMIT) {
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// Time to give up
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own_message_send_state = IDLE;
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if (printf("Could not send message %" PRIu16 "\n", own_message_msgid) == -1) {
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err(1, "printf");
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}
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if (fflush(stdout) == EOF) {
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err(1, "fflush");
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}
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}
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}
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// Process status broadcasting
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int status_broadcast_wait_ms = wait_ms_until(next_status_broadcast);
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if (status_broadcast_wait_ms == 0) {
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// The time has come to send the status broadcast
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send_status(broadcast_mac);
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// Do next one in about 5 minutes
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next_status_broadcast = ms_in_future(5 * 60 * 1000 + 1000 * random_byte() / 64);
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wait_ms = wait_ms_until(next_status_broadcast);
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next_status_broadcast = ms_in_future(EM_STATUS_BROADCAST_TIME);
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}
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// Figure out how many ms to wait
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int wait_ms;
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if (retransmit_wait_ms < status_broadcast_wait_ms) {
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wait_ms = retransmit_wait_ms;
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} else {
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wait_ms = status_broadcast_wait_ms;
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}
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int ready = poll(pollfds, sizeof(pollfds) / sizeof(*pollfds), wait_ms);
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@ -802,7 +887,7 @@ int main(int argc, char **argv) {
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send_status(broadcast_mac);
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// Schedule next broadcast of our status about 5 min in the future
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next_status_broadcast = ms_in_future(5 * 60 * 1000 + 1000 * random_byte() / 64);
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next_status_broadcast = ms_in_future(EM_STATUS_BROADCAST_TIME);
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// Request status from everyone, so that we can get an idea of who is on the network
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send_status_request(broadcast_mac);
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