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osmo-cbc
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initial checkin of cbsp_server.c

This commit is contained in:
Harald Welte 2019-05-05 14:24:43 +02:00
commit 6c8bf25d11
1 changed files with 233 additions and 0 deletions
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src/cbsp_server.c Normal file
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#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/select.h>
#include <osmocom/core/msgb.h>
#include <osmocom/gsm/cbsp.h>
#include <osmocom/netif/stream.h>
/* a CBC server */
struct osmo_cbsp_cbc {
/* libosmo-netif stream server */
struct osmo_stream_srv_link *link;
/* BSCs / clients connected to this CBC */
struct llist_head clients;
};
/* a single (remote) client connected to the (local) CBC server */
struct osmo_cbsp_cbc_client {
/* entry in osmo_cbsp_cbc.clients */
struct llist_head list;
/* stream server connection for this client */
struct osmo_stream_srv *conn;
/* partially received CBSP message (rx completion pending) */
struct msgb *rx_msg;
/* receive call-back; called for every received message */
int (*rx_cb)(struct osmo_cbsp_cbc_client *client, struct osmo_cbsp_decoded *dec);
};
#if 0
struct osmo_cbsp_bsc {
/* libosmo-netif stream client */
struct osmo_stream_cli *stream;
};
#endif
/*! Read one CBSP message from socket fd or store part if still not fully received.
* \param[in] fd The fd for the socket to read from.
* \param[out] rmsg internally allocated msgb containing a fully received CBSP message.
* \param[inout] tmp_msg internally allocated msgb caching data for not yet fully received message.
*
* Function is designed just like ipa_msg_recv_buffered()
*/
int osmo_cbsp_recv_buffered(int fd, struct msgb **rmsg, struct msgb **tmp_msg)
{
struct msgb *msg = tmp_msg ? *tmp_msg : NULL;
struct cbsp_header *h;
int len, rc;
int needed;
if (!msg) {
msg = osmo_cbsp_msgb_alloc(__func__);
if (!msg) {
return -ENOMEM;
goto discard_msg;
}
msg->l1h = msg->tail;
}
if (msg->l2h == NULL) {
/* first read the [missing part of the] header */
needed = sizeof(*h) - msg->len;
rc = recv(fd, msg->tail, needed, 0);
if (rc == 0)
goto discard_msg;
else if (rc < 0) {
if (errno == EAGAIN || errno == EINTR)
rc = 0;
else {
rc = -errno;
goto discard_msg;
}
}
msgb_put(msg, rc);
if (rc < needed) {
if (msg->len == 0) {
rc = -EAGAIN;
goto discard_msg;
}
if (!tmp_msg) {
rc = -EIO;
goto discard_msg;
}
*tmp_msg = msg;
return -EAGAIN;
}
msg->l2h = msg->tail;
}
/* then read the length as specified in the header */
len = h->len[0] << 16 | h->len[1] << 8 | h->len[0];
needed = len - msgb_l2len(msg);
if (needed > 0) {
rc = recv(fd, msg->tail, needed, 0);
if (rc == 0)
goto discard_msg;
else if (rc < 0) {
if (errno == EAGAIN || errno == EINTR)
rc = 0;
else {
rc = -errno;
goto discard_msg;
}
}
msgb_put(msg, rc);
/* still not all of payload received? */
if (rc < needed) {
if (!tmp_msg) {
rc = -EIO;
goto discard_msg;
}
*tmp_msg = msg;
return -EAGAIN;
}
}
/* else: complete message received */
rc = msgb_l2len(msg);
if (rc == 0) {
/* drop empty message */
rc = -EAGAIN;
goto discard_msg;
}
if (tmp_msg)
*tmp_msg = NULL;
*rmsg = msg;
return rc;
discard_msg:
if (tmp_msg)
*tmp_msg = NULL;
msgb_free(msg);
return rc;
}
/* data from BSC has arrived at CBC */
static int cbsp_cbc_read_cb(struct osmo_stream_srv *conn)
{
struct osmo_cbsp_cbc_client *client = osmo_stream_srv_get_data(conn);
struct osmo_fd *ofd = osmo_stream_srv_get_ofd(conn);
struct osmo_cbsp_decoded *decoded;
struct msgb *msg = NULL;
int rc;
/* message de-segmentation */
rc = osmo_cbsp_recv_buffered(ofd->fd, &msg, &client->rx_msg);
if (rc <= 0) {
if (rc == -EAGAIN || rc == -EINTR) {
/* more data needs to be read */
return 0;
} else if (rc == -EPIPE || rc == -ECONNRESET) {
/* lost connection with server */
} else if (rc == 0) {
/* connection closed with server */
}
/* destroy connection */
return -EBADF;
}
OSMO_ASSERT(msg);
/* decode + dispatch message */
decoded = osmo_cbsp_decode(client, msg);
msgb_free(msg);
if (decoded)
client->rx_cb(client, decoded);
return 0;
}
/* connection from BSC to CBC has been closed */
static int cbsp_cbc_closed_cb(struct osmo_stream_srv *conn)
{
struct osmo_cbsp_cbc_client *client = osmo_stream_srv_get_data(conn);
llist_del(&client->list);
talloc_free(client);
return 0;
}
/* new connection from BSC has arrived at CBC */
static int cbsp_cbc_accept_cb(struct osmo_stream_srv_link *link, int fd)
{
struct osmo_cbsp_cbc *cbc = osmo_stream_srv_link_get_data(link);
struct osmo_cbsp_cbc_client *client = talloc_zero(cbc, struct osmo_cbsp_cbc_client);
OSMO_ASSERT(client);
client->conn = osmo_stream_srv_create(link, link, fd, cbsp_cbc_read_cb, cbsp_cbc_closed_cb, client);
if (!client->conn) {
talloc_free(client);
return -1;
}
llist_add_tail(&client->list, &cbc->clients);
return 0;
}
void cbsp_cbc_client_tx(struct osmo_cbsp_cbc_client *client, struct osmo_cbsp_decoded *cbsp)
{
struct msgb *msg = osmo_cbsp_encode(cbsp);
talloc_free(cbsp);
if (!msg) {
/* FIXME */
return;
}
osmo_stream_srv_send(client->conn, msg);
}
/* initialize the CBC-side CBSP server */
struct osmo_cbsp_cbc *cbsp_cbc_create(void *ctx)
{
struct osmo_cbsp_cbc *cbc = talloc_zero(ctx, struct osmo_cbsp_cbc);
int rc;
OSMO_ASSERT(cbc);
INIT_LLIST_HEAD(&cbc->clients);
cbc->link = osmo_stream_srv_link_create(cbc);
osmo_stream_srv_link_set_data(cbc->link, cbc);
osmo_stream_srv_link_set_nodelay(cbc->link, true);
osmo_stream_srv_link_set_port(cbc->link, 48049);
osmo_stream_srv_link_set_accept_cb(cbc->link, cbsp_cbc_accept_cb);
rc = osmo_stream_srv_link_open(cbc->link);
OSMO_ASSERT(rc == 0);
return cbc;
}