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IPC: daemon: add batch-mode support #185

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merged 1 commit into from
Oct 4, 2022
Merged

IPC: daemon: add batch-mode support #185

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154 changes: 103 additions & 51 deletions src/ipc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -43,32 +43,73 @@ extern char *ident;
static struct sockaddr_un sun;
static int ipc_socket = -1;

/* max word count in one command:
* smcroutectl add in1 source group out1 out2 .. out32
*/
#define CMD_MAX_WORDS (MAXVIFS + 3)


/* Receive command from the smcroutectl */
static void ipc_read(int sd)
{
/* since command len must be limited by the max number of oifs
preallocate ipc_msg only once in advance */
char msg_buf[sizeof(struct ipc_msg) + CMD_MAX_WORDS * sizeof(char *)];
char buf[MX_CMDPKT_SZ];
struct ipc_msg *msg;
const char* buf_ptr;
ssize_t rx = 0, rx_curr;
int first_call = 1;

memset(buf, 0, sizeof(buf));
msg = (struct ipc_msg *)ipc_receive(sd, buf, sizeof(buf));
if (!msg) {
/* Skip logging client disconnects */
if (errno != ECONNRESET)
smclog(LOG_WARNING, "Failed receiving IPC message from client: %s", strerror(errno));
return;
}

if (msg_do(sd, msg)) {
if (EINVAL == errno)
smclog(LOG_WARNING, "Unknown or malformed IPC message '%c' from client.", msg->cmd);
errno = 0;
ipc_send(sd, log_message, strlen(log_message) + 1);
} else {
ipc_send(sd, "", 1);
}
/* since client message would be big enough and couldn't fit into buffer
we have to make multiple iterations to receive all data */
while(1) {
rx_curr = ipc_receive(sd, buf + rx, sizeof(buf) - rx, first_call);
first_call = 0;
if(rx_curr <= 0) {
if (errno == EAGAIN)
return; /* no more data from client */
/* Skip logging client disconnects */
else if (errno != ECONNRESET)
smclog(LOG_WARNING, "Failed receiving IPC message from client: %s", strerror(errno));
return;
}

rx += rx_curr;

free(msg);
/* Make sure to always have at least one NUL, for strlen() */
buf[rx] = 0;

buf_ptr = buf;
while(rx > 0) {
struct ipc_msg* msg = (struct ipc_msg*)msg_buf;
/* extract one command at a time */
if (ipc_parse(buf_ptr, rx, msg)) {
if (EAGAIN == errno) {
/* need more data from client?
move last unused bytes (if any) to the begging of the buffer
and lets try to receive more data */
memmove(buf, buf_ptr, rx);
break;
}
smclog(LOG_WARNING, "Failed to parse IPC message from client: %s", strerror(errno));
return;
}

if (msg_do(sd, msg)) {
if (EINVAL == errno)
smclog(LOG_WARNING, "Unknown or malformed IPC message '%c' from client.", msg->cmd);
errno = 0;
ipc_send(sd, log_message, strlen(log_message) + 1);
} else {
ipc_send(sd, "", 1);
}
/* shift to the next command if any and reduce remaining bytes in buffer */
buf_ptr += msg->len;
rx -= msg->len;
}
}
}

static void ipc_accept(int sd, void *arg)
Expand Down Expand Up @@ -149,7 +190,7 @@ void ipc_exit(void)
* Returns:
* Number of bytes successfully sent, or -1 with @errno on failure.
*/
int ipc_send(int sd, char *buf, size_t len)
int ipc_send(int sd, const char *buf, size_t len)
{
if (write(sd, buf, len) != (ssize_t)len)
return -1;
Expand All @@ -162,68 +203,79 @@ int ipc_send(int sd, char *buf, size_t len)
* @sd: Client socket from ipc_accept()
* @buf: Buffer for message
* @len: Size of @buf in bytes
* @first_call: non-zero set on first read after accept, 0 - subsequent calls
*
* Reads a message from the IPC socket and stores in @buf, respecting
* Reads a message(s) from the IPC socket and stores in @buf, respecting
* the size @len. Connects and resets connection as necessary.
*
* Returns:
* Pointer to a successfuly read command packet in @buf, or %NULL on error.
* Size of a successfuly read command packet in @buf, or 0 on error.
*/
void *ipc_receive(int sd, char *buf, size_t len)
ssize_t ipc_receive(int sd, char *buf, size_t len, int first_call)
{
ssize_t sz;
/* since we can call this multiple times during receive of multipart
command lets pass `don't wait` flag to not block forever
when client finish transmission */
int flags = first_call ? 0 : MSG_DONTWAIT;

sz = recv(sd, buf, len - 1, 0);
if (sz <= 0) {
if (!sz)
errno = ECONNRESET;
return NULL;
}
sz = recv(sd, buf, len - 1, flags);
if (!sz)
errno = ECONNRESET;

/* successful read */
if ((size_t)sz >= sizeof(struct ipc_msg)) {
struct ipc_msg *msg = (struct ipc_msg *)buf;
return sz;
}

/* Make sure to always have at least one NUL, for strlen() */
buf[sz] = 0;
/**
* ipc_server_parse - Parse IPC message(s) from client
* @buf: Buffer of message(s)
* @sz: Size of @buf in bytes
* @msg_buf: Preallocated ipc_msg
*
* Parse message(s) from the IPC socket, respecting
* the size @sz.
*
* Returns:
* POSIX OK(0) on a successfuly read command in @buf, or non-zero on error.
*/
int ipc_parse(const char *buf, size_t sz, void* msg_buf)
{
struct ipc_msg* msg;

if ((size_t)sz == msg->len) {
/* successful read */
if (sz >= sizeof(struct ipc_msg)) {
memcpy(msg_buf, buf, sizeof(struct ipc_msg));
msg = (struct ipc_msg*)msg_buf;
/* enough bytes to extract just one message? */
if (sz >= msg->len) {
size_t i, count;
char *ptr;
/* We are not going to modify anything here */
const char *ptr;

/* Upper bound: smcroutectl add in1 source group out1 out2 .. out32 */
count = msg->count;
if (count > (MAXVIFS + 3)) {
if (count > CMD_MAX_WORDS) {
errno = EINVAL;
return NULL;
return 1;
}

msg = malloc(sizeof(struct ipc_msg) + msg->count * sizeof(char *));
if (!msg)
return NULL;

memcpy(msg, buf, sizeof(struct ipc_msg));

ptr = buf + offsetof(struct ipc_msg, argv);
for (i = 0; i < count; i++) {
/* Verify ptr, attacker may set too large msg->count */
if (ptr >= (buf + len)) {
free(msg);
if (ptr >= (buf + msg->len)) {
errno = EBADMSG;
return NULL;
return 1;
}

msg->argv[i] = ptr;
msg->argv[i] = (char*)ptr;
ptr += strlen(ptr) + 1;
}
msg->count = count;

return msg;
return 0;
}
}

/* we've parsed all commands or not enough bytes to parse next */
errno = EAGAIN;
return NULL;
return 1;
}

/**
Expand Down
5 changes: 3 additions & 2 deletions src/ipc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,9 @@
int ipc_init (char *path);
void ipc_exit (void);

int ipc_send (int sd, char *buf, size_t len);
void *ipc_receive (int sd, char *buf, size_t len);
int ipc_send (int sd, const char *buf, size_t len);
ssize_t ipc_receive(int sd, char *buf, size_t len, int first_call);
int ipc_parse (const char *buf, size_t sz, void *msg_buf);

#endif /* SMCROUTE_IPC_H_ */

Expand Down