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#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <pthread.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <sys/signalfd.h>
#include <unistd.h>
#include <cJSON.h>
#include <curl/curl.h>
#include <init.h>
#include <log.h>
#include <subsys.h>
extern int http_get(char *url);
extern void ws_handle_event(cJSON *event);
extern void ws_send_heartbeat();
CURL *ws_handle;
char *gateway_url;
int net_subsystem(void)
{
print(LOG_INFO "net: starting net subsystem");
if(!gateway_url)
panic("net: gateway url invalid");
/* Initialise CURL */
ws_handle = curl_easy_init();
curl_easy_setopt(ws_handle, CURLOPT_URL, gateway_url);
curl_easy_setopt(ws_handle, CURLOPT_CONNECT_ONLY, 2L);
print(LOG_INFO "net: opening ws");
CURLcode ret = curl_easy_perform(ws_handle);
if(ret > 0)
panic("net: cannot open websocket (curl errno %d)", ret);
int ws_sockfd;
if((ret = curl_easy_getinfo(ws_handle,
CURLINFO_ACTIVESOCKET, &ws_sockfd)) != CURLE_OK)
panic("net: curl cannot get active socket (errno %d)", ret);
/* Block ALRM */
sigset_t *set = malloc(sizeof(sigset_t));
sigaddset(set, SIGALRM);
sigprocmask(SIG_BLOCK, set, NULL);
int alrmfd = signalfd(-1, set, 0);
free(set);
/* Prepare poll */
struct pollfd pollarray[2] = {
{
.fd = ws_sockfd,
.events = POLLIN,
.revents = POLLIN
},
{
.fd = alrmfd,
.events = POLLIN,
.revents = 0
}
};
struct pollfd *sockpoll = &(pollarray[0]);
struct pollfd *alrmpoll = &(pollarray[1]);
/* Misc. variables */
char *inbuf = malloc(1<<16 * sizeof(char));
size_t rlen;
const struct curl_ws_frame *meta;
errno = 0;
do {
if((sockpoll->revents & POLLIN) == POLLIN) {
ret = curl_ws_recv(ws_handle, inbuf, 1<<16, &rlen, &meta);
/* sometimes only SSL information gets sent through, so no actual
data is received. curl uses NONBLOCK internally so it lets us
know if there is no more data remaining */
if(ret == CURLE_AGAIN)
continue;
if(ret != CURLE_OK) {
print(LOG_ERR "net: encountered curl error while reading "
"socket (curl errno %d)", ret);
break;
}
/* TODO: partial frames */
if((meta->offset | meta->bytesleft) > 0) {
print(LOG_ERR "net: dropped partial frame");
continue;
}
cJSON *event = cJSON_ParseWithLength(inbuf, rlen);
if(!event) {
print(LOG_ERR "net: dropped malformed frame");
continue;
}
ws_handle_event(event);
cJSON_Delete(event);
} else if((sockpoll->revents &
(POLLRDHUP | POLLERR | POLLHUP | POLLNVAL)) > 0) {
print(LOG_ERR "net: encountered error on socket (revents %d)",
sockpoll->revents);
break;
}
if((alrmpoll->revents & POLLIN) == POLLIN) {
struct signalfd_siginfo siginfo;
read(alrmfd, &siginfo, sizeof(struct signalfd_siginfo));
ws_send_heartbeat();
}
} while(poll(pollarray, 2, -1) >= 0);
if(errno > 0) {
print(LOG_ERR "net: error encountered while polling"
" (errno %d)", errno);
}
free(inbuf);
curl_easy_cleanup(ws_handle);
panic("net: websocket closed unexpectedly");
return 0;
}
void net_get_gateway_url()
{
/* determine if websockets are supported */
curl_version_info_data *curl_version =
curl_version_info(CURLVERSION_NOW);
const char * const* curl_protocols = curl_version->protocols;
int wss_supported = 0;
for(int i = 0; curl_protocols[i]; ++i) {
if(strcmp(curl_protocols[i], "wss") == 0) {
wss_supported = 1;
break;
}
}
if(!wss_supported)
panic("net: wss not supported by libcurl");
/* fetch preferred url from discord */
int fd = http_get("https://discord.com/api/gateway/bot");
if(fd < 0) {
print(LOG_ERR "net: failed to get gateway url (error %d)", -fd);
goto assume;
}
char buf[512];
int buf_length = read(fd, buf, 512);
close(fd);
cJSON *gateway_info = cJSON_ParseWithLength(buf, buf_length);
cJSON *gateway_url_json =
cJSON_GetObjectItemCaseSensitive(gateway_info, "url");
if(!cJSON_IsString(gateway_url_json) ||
gateway_url_json->valuestring == NULL) {
print(LOG_ERR "net: cannot get gateway url from api "
"(token invalid?)");
cJSON_Delete(gateway_info);
goto assume;
}
/* curl requires websocket secure URLs to begin with WSS instead
of wss, so we fix up the received url for curl */
gateway_url = calloc(strlen(gateway_url_json->valuestring) + 1,
sizeof(char));
strcpy(gateway_url, gateway_url_json->valuestring);
gateway_url[0] = 'W';
gateway_url[1] = 'S';
gateway_url[2] = 'S';
print(LOG_DEBUG "net: using gateway url %s", gateway_url);
cJSON_Delete(gateway_info);
return;
assume:
print(LOG_DEBUG "net: assuming gateway url WSS://gateway.discord.gg");
gateway_url = calloc(strlen("WSS://gateway.discord.gg") + 1,
sizeof(char));
strcpy(gateway_url, "WSS://gateway.discord.gg");
return;
}
l1_initcall(net_get_gateway_url);
void net_initcall()
{
start_subsystem(net_subsystem);
}
l2_initcall(net_initcall);
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