krb5 commit: Simplify sendto_kdc exception handling
Greg Hudson
ghudson at MIT.EDU
Fri Apr 12 14:29:11 EDT 2013
https://github.com/krb5/krb5/commit/6e2a5464d5900eebfa84aaf8255645edeada3311
commit 6e2a5464d5900eebfa84aaf8255645edeada3311
Author: Greg Hudson <ghudson at mit.edu>
Date: Fri Apr 12 14:25:51 2013 -0400
Simplify sendto_kdc exception handling
src/lib/krb5/os/sendto_kdc.c | 108 ++++++++++--------------------------------
1 files changed, 25 insertions(+), 83 deletions(-)
diff --git a/src/lib/krb5/os/sendto_kdc.c b/src/lib/krb5/os/sendto_kdc.c
index e476a2c..3e4ec7e 100644
--- a/src/lib/krb5/os/sendto_kdc.c
+++ b/src/lib/krb5/os/sendto_kdc.c
@@ -88,7 +88,6 @@ struct incoming_krb5_message {
struct conn_state {
SOCKET fd;
- krb5_error_code err;
enum conn_states state;
unsigned int is_udp : 1;
int (*service)(krb5_context context, struct conn_state *,
@@ -459,7 +458,6 @@ add_connection(struct conn_state **conns, struct addrinfo *ai,
if (state == NULL)
return ENOMEM;
state->state = INITIALIZING;
- state->err = 0;
state->x.out.sgp = state->x.out.sgbuf;
state->addr.type = ai->ai_socktype;
state->addr.family = ai->ai_family;
@@ -622,10 +620,8 @@ start_connection(krb5_context context, struct conn_state *state,
static const struct linger lopt = { 0, 0 };
fd = socket(state->addr.family, state->addr.type, 0);
- if (fd == INVALID_SOCKET) {
- state->err = SOCKET_ERRNO;
+ if (fd == INVALID_SOCKET)
return -1; /* try other hosts */
- }
set_cloexec_fd(fd);
/* Make it non-blocking. */
ioctlsocket(fd, FIONBIO, (const void *) &one);
@@ -646,7 +642,6 @@ start_connection(krb5_context context, struct conn_state *state,
state->fd = fd;
} else {
(void) closesocket(fd);
- state->err = SOCKET_ERRNO;
state->state = FAILED;
return -2;
}
@@ -670,7 +665,6 @@ start_connection(krb5_context context, struct conn_state *state,
&state->callback_buffer);
if (e != 0) {
(void) closesocket(fd);
- state->err = e;
state->fd = INVALID_SOCKET;
state->state = FAILED;
return -3;
@@ -754,13 +748,12 @@ maybe_send(krb5_context context, struct conn_state *conn,
}
static void
-kill_conn(struct conn_state *conn, struct select_state *selstate, int err)
+kill_conn(struct conn_state *conn, struct select_state *selstate)
{
cm_remove_fd(selstate, conn->fd);
closesocket(conn->fd);
conn->fd = INVALID_SOCKET;
conn->state = FAILED;
- conn->err = err;
}
/* Check socket for error. */
@@ -781,46 +774,23 @@ get_so_error(int fd)
return sockerr;
}
-/* Return nonzero only if we're finished and the caller should exit
- its loop. This happens in two cases: We have a complete message,
- or the socket has closed and no others are open. */
-
+/* Process events on a TCP socket. Return 1 if we get a complete reply. */
static int
service_tcp_fd(krb5_context context, struct conn_state *conn,
struct select_state *selstate, int ssflags)
{
int e = 0;
ssize_t nwritten, nread;
+ SOCKET_WRITEV_TEMP tmp;
- if (!(ssflags & (SSF_READ|SSF_WRITE|SSF_EXCEPTION)))
- abort();
- switch (conn->state) {
- SOCKET_WRITEV_TEMP tmp;
+ /* Check for a socket exception or readable data before we expect it. */
+ if (ssflags & SSF_EXCEPTION ||
+ ((ssflags & SSF_READ) && conn->state != READING))
+ goto kill_conn;
+ switch (conn->state) {
case CONNECTING:
- if (ssflags & SSF_READ) {
- /* Bad -- the KDC shouldn't be sending to us first. */
- e = EINVAL /* ?? */;
- kill_conn:
- TRACE_SENDTO_KDC_TCP_DISCONNECT(context, &conn->addr);
- kill_conn(conn, selstate, e);
- return e == 0;
- }
- if (ssflags & SSF_EXCEPTION) {
- handle_exception:
- e = get_so_error(conn->fd);
- goto kill_conn;
- }
-
- /*
- * Connect finished -- but did it succeed or fail?
- * UNIX sets can_write if failed.
- * Call getsockopt to see if error pending.
- *
- * (For most UNIX systems it works to just try writing the
- * first time and detect an error. But Bill Dodd at IBM
- * reports that some version of AIX, SIGPIPE can result.)
- */
+ /* Check whether the connection succeeded. */
e = get_so_error(conn->fd);
if (e) {
TRACE_SENDTO_KDC_TCP_ERROR_CONNECT(context, &conn->addr, e);
@@ -828,27 +798,18 @@ service_tcp_fd(krb5_context context, struct conn_state *conn,
}
conn->state = WRITING;
+ /* Record this connection's timeout for service_fds. */
if (get_curtime_ms(&conn->endtime) == 0)
conn->endtime += 10000;
- goto try_writing;
-
+ /* Fall through. */
case WRITING:
- if (ssflags & SSF_READ) {
- e = E2BIG;
- /* Bad -- the KDC shouldn't be sending anything yet. */
- goto kill_conn;
- }
- if (ssflags & SSF_EXCEPTION)
- goto handle_exception;
-
- try_writing:
TRACE_SENDTO_KDC_TCP_SEND(context, &conn->addr);
nwritten = SOCKET_WRITEV(conn->fd, conn->x.out.sgp,
conn->x.out.sg_count, tmp);
if (nwritten < 0) {
- e = SOCKET_ERRNO;
- TRACE_SENDTO_KDC_TCP_ERROR_SEND(context, &conn->addr, e);
+ TRACE_SENDTO_KDC_TCP_ERROR_SEND(context, &conn->addr,
+ SOCKET_ERRNO);
goto kill_conn;
}
while (nwritten) {
@@ -860,19 +821,11 @@ service_tcp_fd(krb5_context context, struct conn_state *conn,
nwritten -= SG_LEN(sgp);
conn->x.out.sgp++;
conn->x.out.sg_count--;
- if (conn->x.out.sg_count == 0 && nwritten != 0)
- /* Wrote more than we wanted to? */
- abort();
}
}
if (conn->x.out.sg_count == 0) {
- /* Done writing, switch to reading. */
- /* Don't call shutdown at this point because
- * some implementations cannot deal with half-closed connections.*/
+ /* Done writing, switch to reading. */
cm_unset_write(selstate, conn->fd);
- /* Q: How do we detect failures to send the remaining data
- to the remote side, since we're in non-blocking mode?
- Will we always get errors on the reading side? */
conn->state = READING;
conn->x.in.bufsizebytes_read = 0;
conn->x.in.bufsize = 0;
@@ -883,30 +836,18 @@ service_tcp_fd(krb5_context context, struct conn_state *conn,
return 0;
case READING:
- if (ssflags & SSF_EXCEPTION) {
- if (conn->x.in.buf) {
- free(conn->x.in.buf);
- conn->x.in.buf = 0;
- }
- goto handle_exception;
- }
-
if (conn->x.in.bufsizebytes_read == 4) {
/* Reading data. */
nread = SOCKET_READ(conn->fd, conn->x.in.pos, conn->x.in.n_left);
if (nread <= 0) {
e = nread ? SOCKET_ERRNO : ECONNRESET;
- free(conn->x.in.buf);
- conn->x.in.buf = 0;
TRACE_SENDTO_KDC_TCP_ERROR_RECV(context, &conn->addr, e);
goto kill_conn;
}
conn->x.in.n_left -= nread;
conn->x.in.pos += nread;
- if (conn->x.in.n_left <= 0) {
- /* We win! */
+ if (conn->x.in.n_left <= 0)
return 1;
- }
} else {
/* Reading length. */
nread = SOCKET_READ(conn->fd,
@@ -921,17 +862,12 @@ service_tcp_fd(krb5_context context, struct conn_state *conn,
if (conn->x.in.bufsizebytes_read == 4) {
unsigned long len = load_32_be (conn->x.in.bufsizebytes);
/* Arbitrary 1M cap. */
- if (len > 1 * 1024 * 1024) {
- e = E2BIG;
+ if (len > 1 * 1024 * 1024)
goto kill_conn;
- }
conn->x.in.bufsize = conn->x.in.n_left = len;
conn->x.in.buf = conn->x.in.pos = malloc(len);
- if (conn->x.in.buf == 0) {
- /* allocation failure */
- e = ENOMEM;
+ if (conn->x.in.buf == 0)
goto kill_conn;
- }
}
}
break;
@@ -940,8 +876,14 @@ service_tcp_fd(krb5_context context, struct conn_state *conn,
abort();
}
return 0;
+
+kill_conn:
+ TRACE_SENDTO_KDC_TCP_DISCONNECT(context, &conn->addr);
+ kill_conn(conn, selstate);
+ return 0;
}
+/* Process events on a UDP socket. Return 1 if we get a reply. */
static int
service_udp_fd(krb5_context context, struct conn_state *conn,
struct select_state *selstate, int ssflags)
@@ -956,7 +898,7 @@ service_udp_fd(krb5_context context, struct conn_state *conn,
nread = recv(conn->fd, conn->x.in.buf, conn->x.in.bufsize, 0);
if (nread < 0) {
TRACE_SENDTO_KDC_UDP_ERROR_RECV(context, &conn->addr, SOCKET_ERRNO);
- kill_conn(conn, selstate, SOCKET_ERRNO);
+ kill_conn(conn, selstate);
return 0;
}
conn->x.in.pos = conn->x.in.buf + nread;
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