/*
* moves data from one fd to other
*
* returns number of bytes copied if success
* returns 0 (FD_CNXCLOSED) if incoming socket closed
* returns FD_NODATA if no data was available
* returns FD_STALLED if data was read, could not be written, and has been
* stored in temporary buffer.
*/
int fd2fd(struct queue *target_q, struct queue *from_q)
{
char buffer[BUFSIZ];
int target, from, size_r, size_w;
target = target_q->fd;
from = from_q->fd;
size_r = read(from, buffer, sizeof(buffer));
if (size_r == -1) {
switch (errno) {
case EAGAIN:
if (verbose)
fprintf(stderr, "reading 0 from %d\n", from);
return FD_NODATA;
case ECONNRESET:
case EPIPE:
return FD_CNXCLOSED;
}
}
CHECK_RES_RETURN(size_r, "read");
if (size_r == 0)
return FD_CNXCLOSED;
size_w = write(target, buffer, size_r);
/* process -1 when we know how to deal with it */
if (size_w == -1) {
switch (errno) {
case EAGAIN:
/* write blocked: Defer data */
defer_write(target_q, buffer, size_r);
return FD_STALLED;
case ECONNRESET:
case EPIPE:
/* remove end closed -- drop the connection */
return FD_CNXCLOSED;
}
} else if (size_w < size_r) {
/* incomplete write -- defer the rest of the data */
defer_write(target_q, buffer + size_w, size_r - size_w);
return FD_STALLED;
}
CHECK_RES_RETURN(size_w, "write");
return size_w;
}
/*
* Read the beginning of data coming from the client connection and check if
* it's a known protocol.
* Return PROBE_AGAIN if not enough data, or PROBE_MATCH if it succeeded in
* which case cnx->proto is set to the appropriate protocol.
*/
int probe_client_protocol(struct connection *cnx)
{
char buffer[BUFSIZ];
struct proto *p;
int n;
n = read(cnx->q[0].fd, buffer, sizeof(buffer));
/* It's possible that read() returns an error, e.g. if the client
* disconnected between the previous call to select() and now. If that
* happens, we just connect to the default protocol so the caller of this
* function does not have to deal with a specific failure condition (the
* connection will just fail later normally). */
if (n > 0) {
int res = PROBE_NEXT;
defer_write(&cnx->q[1], buffer, n);
for (p = cnx->proto; p && res == PROBE_NEXT; p = p->next) {
if (! p->probe) continue;
if (verbose) fprintf(stderr, "probing for %s\n", p->description);
cnx->proto = p;
res = p->probe(cnx->q[1].begin_deferred_data, cnx->q[1].deferred_data_size, p);
}
if (res != PROBE_NEXT)
return res;
}
if (verbose)
fprintf(stderr,
"all probes failed, connecting to first protocol: %s\n",
protocols->description);
/* If none worked, return the first one affected (that's completely
* arbitrary) */
cnx->proto = protocols;
return PROBE_MATCH;
}
