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linux: deduplicate esp receive logic in esptun

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Unify the two similar serial receive loops.
(as a bonus we'll no longer lose packets that come in through the ESP during
esp_tx_packet)
This commit is contained in:
Wladimir J. van der Laan 2020-02-22 11:17:06 +00:00
parent d9750dcf73
commit 885357f22f
1 changed files with 39 additions and 66 deletions
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105
linux/esptun.c
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@ -41,6 +41,8 @@ uint8_t esp_buffer[ESP_BUFSIZE];
uint8_t tap_buffer[TAP_BUFSIZE];
size_t tap2net;
size_t net2tap;
int esp_fd = -1;
int tun_fd = -1;
/**
* Prints debugging.
@ -342,8 +344,15 @@ static bool is_prefix(const uint8_t *esp_buffer, size_t len, const uint8_t *pref
return true;
}
/** Send a packet to tun interface. */
static void tun_tx_packet(int fd, const uint8_t *esp_buffer, size_t size) {
if (write(fd, esp_buffer, size) <= 0) {
log_info(WARNING, "warning: error writing to tun: %s\n", strerror(errno));
}
}
/** Get OK/FAIL status after running a command on the ESP. */
static bool esp_read_responses(int fd)
static bool esp_read_responses(int fd, bool early_terminate)
{
/** TODO handle timeouts. */
size_t end = 0;
@ -354,10 +363,12 @@ static bool esp_read_responses(int fd)
exit(1);
}
end += n;
size_t ptr = 0;
while (ptr < end) {
const uint8_t *resp = &esp_buffer[ptr];
size_t len = esp_response_is_complete(resp, end - ptr, NULL);
struct packet_info pkt_info;
size_t len = esp_response_is_complete(resp, end - ptr, &pkt_info);
if (len) {
log_debug("<-: ");
debug_response(resp, len);
@ -379,6 +390,12 @@ static bool esp_read_responses(int fd)
if (is_prefix(resp, len, S("WIFI "))) {
log_info(INFO2, " %.*s\n", len - 2, resp);
}
/* Did we receive a packet? */
if (is_prefix(resp, len, pktprefix, sizeof(pktprefix)) && tun_fd != -1) {
log_debug("NET2TUN %lu: Read %d bytes from the esp interface\n", net2tap, pkt_info.payload_len);
net2tap++;
tun_tx_packet(tun_fd, pkt_info.payload, pkt_info.payload_len);
}
/* On non-final response, keep reading. */
} else {
@ -394,6 +411,10 @@ static bool esp_read_responses(int fd)
/* Remove processed responses from esp_buffer by shifting bytes. */
memmove(esp_buffer, &esp_buffer[ptr], end - ptr);
end -= ptr;
if (early_terminate && end == 0) {
/* All responses processed, back to select so that packets from tun get a chance. */
return true;
}
}
}
@ -402,16 +423,9 @@ static void esp_tx_packet(int fd, const uint8_t *esp_buffer, size_t size) {
write_all(fd, S("AT+CIPSEND="));
write_uint(fd, size);
write_all(fd, S("\r\n"));
if (esp_read_responses(fd)) {
if (esp_read_responses(fd, false)) {
write_all(fd, esp_buffer, size);
esp_read_responses(fd);
}
}
/** Send a packet to tun interface. */
static void tun_tx_packet(int fd, const uint8_t *esp_buffer, size_t size) {
if (write(fd, esp_buffer, size) <= 0) {
log_info(WARNING, "warning: error writing to tun: %s\n", strerror(errno));
esp_read_responses(fd, false);
}
}
@ -429,7 +443,7 @@ int main(int argc, char **argv)
const char *host = argv[5];
int port = atoi(argv[6]);
int esp_fd = open(portname, O_RDWR | O_NOCTTY | O_SYNC);
esp_fd = open(portname, O_RDWR | O_NOCTTY | O_SYNC);
if (esp_fd < 0) {
my_err("Error opening %s: %s", portname, strerror(errno));
}
@ -438,7 +452,6 @@ int main(int argc, char **argv)
setup_uart(esp_fd, 115200);
/* initialize tun/tap interface */
int tun_fd;
if ((tun_fd = tun_alloc(if_name, IFF_TUN | IFF_NO_PI)) < 0) {
my_err("Error connecting to tun interface %s!\n", if_name);
}
@ -447,17 +460,17 @@ int main(int argc, char **argv)
log_info(INFO1, "Initializing device\n");
write_all(esp_fd, S("ATE0\r\n"));
if (!esp_read_responses(esp_fd)) {
if (!esp_read_responses(esp_fd, false)) {
my_err("Could not disable echo");
}
write_all(esp_fd, S("AT+CWMODE_CUR=1\r\n"));
if (!esp_read_responses(esp_fd)) {
if (!esp_read_responses(esp_fd, false)) {
my_err("Could not switch to station mode");
}
write_all(esp_fd, S("AT+CIPMUX=0\r\n"));
if (!esp_read_responses(esp_fd)) {
if (!esp_read_responses(esp_fd, false)) {
my_err("Could not switch to single-connection mode");
}
@ -465,13 +478,13 @@ int main(int argc, char **argv)
write_all(esp_fd, S("AT+UART_CUR="));
write_uint(esp_fd, BAUDRATE);
write_all(esp_fd, S(",8,1,0,0\r\n"));
if (!esp_read_responses(esp_fd)) {
if (!esp_read_responses(esp_fd, false)) {
my_err("Could not set faster baudrate");
}
setup_uart(esp_fd, BAUDRATE);
write_all(esp_fd, S("AT\r\n"));
if (!esp_read_responses(esp_fd)) {
if (!esp_read_responses(esp_fd, false)) {
my_err("AT test unsuccesful: new baudrate unstable?");
}
@ -481,12 +494,12 @@ int main(int argc, char **argv)
write_all(esp_fd, S("\",\""));
write_esc(esp_fd, passwd, strlen(passwd));
write_all(esp_fd, S("\"\r\n"));
if (!esp_read_responses(esp_fd)) {
if (!esp_read_responses(esp_fd, false)) {
my_err("Could not connect to AP");
}
write_all(esp_fd, S("AT+CIPSTA_CUR?\r\n"));
if (!esp_read_responses(esp_fd)) {
if (!esp_read_responses(esp_fd, false)) {
my_err("Could not query IP");
}
@ -498,7 +511,7 @@ int main(int argc, char **argv)
write_all(esp_fd, S(","));
write_uint(esp_fd, port); /* local port is same as remote port for now */
write_all(esp_fd, S("\r\n"));
if (!esp_read_responses(esp_fd)) {
if (!esp_read_responses(esp_fd, false)) {
my_err("Could not open UDP connection");
}
@ -508,7 +521,7 @@ int main(int argc, char **argv)
if (daemon(0, 0) < 0) {
my_err("Could not go to background\n");
}
debug = 0; /* no use to log anything after this */
debug = false; /* no use to log anything after this */
struct pollfd fds[2] = {
{esp_fd, POLLIN, 0},
@ -526,50 +539,10 @@ int main(int argc, char **argv)
/* Handle input from UART */
if (fds[0].revents & POLLIN) {
/* Read all available responses entirely */
size_t end = 0;
while (true) {
ssize_t n = read(esp_fd, &esp_buffer[end], ESP_BUFSIZE - end);
if (n <= 0) {
perror("Reading from UART");
exit(1);
}
end += n;
size_t ptr = 0;
while (ptr < end) {
const uint8_t *resp = &esp_buffer[ptr];
struct packet_info pkt_info;
size_t len = esp_response_is_complete(resp, end - ptr, &pkt_info);
if (len) {
log_debug("<-: ");
debug_response(resp, len);
log_debug("\n");
if (is_prefix(resp, len, pktprefix, sizeof(pktprefix))) {
/* Received UDP packet. */
log_debug("NET2TUN %lu: Read %d bytes from the esp interface\n", net2tap, pkt_info.payload_len);
net2tap++;
tun_tx_packet(tun_fd, pkt_info.payload, pkt_info.payload_len);
}
} else {
if (end == ESP_BUFSIZE) {
/* Buffer full but command wasn't complete - this isn't good,
* exit to prevent looping forever. */
my_err("Buffer full with unterminated command");
}
break;
}
ptr += len;
}
/* Remove processed responses from esp_buffer */
memmove(esp_buffer, &esp_buffer[ptr], end - ptr);
end -= ptr;
if (!end) {
/* All responses processed, back to select. */
break;
}
}
/* Read all data available from the UART, before processing data from TUN, to make sure we don't miss any.
* TODO: There can still be data loss at high baudrates, unfortunately, this needs logic to re-sync with the device in this case.
*/
esp_read_responses(esp_fd, true);
}
// Handle input from TUN