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VILLASnode/lib/api.c

247 lines
5.2 KiB
C

/** REST-API-releated functions.
*
* @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
* @copyright 2017, Institute for Automation of Complex Power Systems, EONERC
*********************************************************************************/
#include <libwebsockets.h>
#include "plugin.h"
#include "api.h"
#include "log.h"
#include "config.h"
static int parse_request(struct api_buffer *b, json_t **req)
{
json_error_t e;
if (b->len <= 0)
return -1;
*req = json_loadb(b->buf, b->len, JSON_DISABLE_EOF_CHECK, &e);
if (!*req)
return -1;
if (e.position < b->len) {
void *dst = (void *) b->buf;
void *src = (void *) (b->buf + e.position);
memmove(dst, src, b->len - e.position);
b->len -= e.position;
}
return 1;
}
#if JANSSON_VERSION_HEX < 0x020A00
size_t json_dumpb(const json_t *json, char *buffer, size_t size, size_t flags)
{
char *str;
size_t len;
str = json_dumps(json, flags);
if (!str)
return 0;
len = strlen(str) - 1; // not \0 terminated
if (buffer && len <= size)
memcpy(buffer, str, len);
//free(str);
return len;
}
#endif
static int unparse_response(struct api_buffer *b, json_t *res)
{
size_t len;
retry: len = json_dumpb(res, b->buf + b->len, b->size - b->len, 0);
if (len > b->size - b->len) {
b->buf = realloc(b->buf, b->len + len);
b->len += len;
goto retry;
}
return 0;
}
int api_session_run_command(struct api_session *s, json_t *req, json_t **resp)
{
int ret;
const char *rstr;
struct plugin *p;
json_t *args;
ret = json_unpack(req, "{ s: s, s: o }",
"command", &rstr,
"arguments", &args);
if (ret)
*resp = json_pack("{ s: s, s: d }",
"error", "invalid request",
"code", -1);
p = plugin_lookup(PLUGIN_TYPE_API, rstr);
if (!p)
*resp = json_pack("{ s: s, s: d, s: s }",
"error", "command not found",
"code", -2,
"command", rstr);
debug(LOG_API, "Running API request: %s with arguments: %s", p->name, json_dumps(args, 0));
ret = p->api.cb(&p->api, args, resp, s);
if (ret)
*resp = json_pack("{ s: s, s: d }",
"error", "command failed",
"code", ret);
debug(LOG_API, "API request completed with code: %d and output: %s", ret, json_dumps(*resp, 0));
return 0;
}
int api_protocol_cb(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len)
{
int ret;
struct api_session *s = (struct api_session *) user;
switch (reason) {
case LWS_CALLBACK_ESTABLISHED: {
struct web *w = (struct web *) lws_context_user(lws_get_context(wsi));
api_session_init(s, w->api, API_MODE_WS);
break;
}
case LWS_CALLBACK_HTTP: {
struct web *w = (struct web *) lws_context_user(lws_get_context(wsi));
char *uri = (char *) in;
/* Parse request URI */
ret = sscanf(uri, "/api/v%d", (int *) &s->version);
if (ret != 1)
return -1;
debug(LOG_API, "New REST API session initiated: version = %d", s->version);
api_session_init(s, w->api, API_MODE_HTTP);
/* Prepare HTTP response header */
s->response.headers.len = 1 + asprintf(&s->response.headers.buf,
"HTTP/1.1 200 OK\r\n"
"Content-type: application/json\r\n"
"User-agent: " USER_AGENT
"\r\n"
);
/* book us a LWS_CALLBACK_HTTP_WRITEABLE callback */
lws_callback_on_writable(wsi);
break;
}
case LWS_CALLBACK_CLIENT_RECEIVE:
case LWS_CALLBACK_RECEIVE:
case LWS_CALLBACK_HTTP_BODY: {
char *newbuf;
newbuf = realloc(s->request.body.buf, s->request.body.len + len);
s->request.body.buf = memcpy(newbuf + s->request.body.len, in, len);
s->request.body.len += len;
json_t *req, *resp;
while (parse_request(&s->request.body, &req) == 1) {
api_session_run_command(s, req, &resp);
unparse_response(&s->response.body, resp);
debug(LOG_WEB, "Sending response: %s len=%zu", s->response.body.buf, s->response.body.len);
lws_callback_on_writable(wsi);
}
break;
}
case LWS_CALLBACK_HTTP_BODY_COMPLETION:
s->completed = true;
break;
case LWS_CALLBACK_SERVER_WRITEABLE:
case LWS_CALLBACK_HTTP_WRITEABLE: {
int sent;
if (s->mode == API_MODE_HTTP && s->response.headers.len > 0) {
sent = lws_write(wsi, s->response.headers.buf, s->response.headers.len, LWS_WRITE_HTTP_HEADERS);
if (sent > 0) {
memmove(s->response.headers.buf, s->response.headers.buf + sent, sent);
s->response.headers.len -= sent;
}
}
else if (s->response.body.len > 0) {
sent = lws_write(wsi, s->response.body.buf, s->response.body.len, LWS_WRITE_HTTP);
if (sent > 0) {
memmove(s->response.body.buf, s->response.body.buf + sent, sent);
s->response.body.len -= sent;
}
}
if (s->completed && s->response.body.len == 0)
return -1;
break;
}
default:
return 0;
}
return 0;
}
int api_init(struct api *a, struct cfg *cfg)
{
list_init(&a->sessions);
a->cfg = cfg;
return 0;
}
int api_destroy(struct api *a)
{
return 0;
}
int api_deinit(struct api *a)
{
list_destroy(&a->sessions, (dtor_cb_t) api_session_destroy, false);
return 0;
}
int api_session_init(struct api_session *s, struct api *a, enum api_mode m)
{
s->mode = m;
s->api = a;
s->completed = false;
s->request.body =
s->response.body =
s->response.headers = (struct api_buffer) { 0 };
return 0;
}
int api_session_destroy(struct api_session *s)
{
return 0;
}