ofp-util: Don't return static data in ofputil_packet_in_reason_to_string().

Returning a static data buffer makes code more brittle and definitely
not thread-safe, so this commit switches to using a caller-provided
buffer instead.

Signed-off-by: Ben Pfaff <blp@nicira.com>

diff --git a/lib/ofp-actions.c b/lib/ofp-actions.c
index 58d0098..c9e000f 100644 (file)
--- a/lib/ofp-actions.c
+++ b/lib/ofp-actions.c
@@ -2090,8 +2090,11 @@ ofpact_format(const struct ofpact *a, struct ds *s)
 
             ds_put_cstr(s, "controller(");
             if (reason != OFPR_ACTION) {
+                char reasonbuf[OFPUTIL_PACKET_IN_REASON_BUFSIZE];
+
                 ds_put_format(s, "reason=%s,",
-                              ofputil_packet_in_reason_to_string(reason));
+                              ofputil_packet_in_reason_to_string(
+                                  reason, reasonbuf, sizeof reasonbuf));
             }
             if (controller->max_len != UINT16_MAX) {
                 ds_put_format(s, "max_len=%"PRIu16",", controller->max_len);

diff --git a/lib/ofp-print.c b/lib/ofp-print.c
index 0a9917a..9471385 100644 (file)
--- a/lib/ofp-print.c
+++ b/lib/ofp-print.c
@@ -86,6 +86,7 @@ static void
 ofp_print_packet_in(struct ds *string, const struct ofp_header *oh,
                     int verbosity)
 {
+    char reasonbuf[OFPUTIL_PACKET_IN_REASON_BUFSIZE];
     struct ofputil_packet_in pin;
     int error;
     int i;
@@ -130,7 +131,8 @@ ofp_print_packet_in(struct ds *string, const struct ofp_header *oh,
     }
 
     ds_put_format(string, " (via %s)",
-                  ofputil_packet_in_reason_to_string(pin.reason));
+                  ofputil_packet_in_reason_to_string(pin.reason, reasonbuf,
+                                                     sizeof reasonbuf));
 
     ds_put_format(string, " data_len=%zu", pin.packet_len);
     if (pin.buffer_id == UINT32_MAX) {
@@ -1661,8 +1663,12 @@ ofp_print_nxt_set_async_config(struct ds *string,
         ds_put_cstr(string, "       PACKET_IN:");
         for (j = 0; j < 32; j++) {
             if (nac->packet_in_mask[i] & htonl(1u << j)) {
-                ds_put_format(string, " %s",
-                              ofputil_packet_in_reason_to_string(j));
+                char reasonbuf[OFPUTIL_PACKET_IN_REASON_BUFSIZE];
+                const char *reason;
+
+                reason = ofputil_packet_in_reason_to_string(j, reasonbuf,
+                                                            sizeof reasonbuf);
+                ds_put_format(string, " %s", reason);
             }
         }
         if (!nac->packet_in_mask[i]) {

diff --git a/lib/ofp-util.c b/lib/ofp-util.c
index cc2dc36..26da477 100644 (file)
--- a/lib/ofp-util.c
+++ b/lib/ofp-util.c
@@ -2656,11 +2656,13 @@ ofputil_encode_packet_in(const struct ofputil_packet_in *pin,
     return packet;
 }
 
+/* Returns a string form of 'reason'.  The return value is either a statically
+ * allocated constant string or the 'bufsize'-byte buffer 'reasonbuf'.
+ * 'bufsize' should be at least OFPUTIL_PACKET_IN_REASON_BUFSIZE. */
 const char *
-ofputil_packet_in_reason_to_string(enum ofp_packet_in_reason reason)
+ofputil_packet_in_reason_to_string(enum ofp_packet_in_reason reason,
+                                   char *reasonbuf, size_t bufsize)
 {
-    static char s[INT_STRLEN(int) + 1];
-
     switch (reason) {
     case OFPR_NO_MATCH:
         return "no_match";
@@ -2671,8 +2673,8 @@ ofputil_packet_in_reason_to_string(enum ofp_packet_in_reason reason)
 
     case OFPR_N_REASONS:
     default:
-        sprintf(s, "%d", (int) reason);
-        return s;
+        snprintf(reasonbuf, bufsize, "%d", (int) reason);
+        return reasonbuf;
     }
 }
 
@@ -2683,7 +2685,12 @@ ofputil_packet_in_reason_from_string(const char *s,
     int i;
 
     for (i = 0; i < OFPR_N_REASONS; i++) {
-        if (!strcasecmp(s, ofputil_packet_in_reason_to_string(i))) {
+        char reasonbuf[OFPUTIL_PACKET_IN_REASON_BUFSIZE];
+        const char *reason_s;
+
+        reason_s = ofputil_packet_in_reason_to_string(i, reasonbuf,
+                                                      sizeof reasonbuf);
+        if (!strcasecmp(s, reason_s)) {
             *reason = i;
             return true;
         }

diff --git a/lib/ofp-util.h b/lib/ofp-util.h
index 010c34d..1c8d6cd 100644 (file)
--- a/lib/ofp-util.h
+++ b/lib/ofp-util.h
@@ -27,6 +27,7 @@
 #include "netdev.h"
 #include "openflow/nicira-ext.h"
 #include "openvswitch/types.h"
+#include "type-props.h"
 
 struct ofpbuf;
 
@@ -334,7 +335,10 @@ struct ofpbuf *ofputil_encode_packet_in(const struct ofputil_packet_in *,
                                         enum ofputil_protocol protocol,
                                         enum nx_packet_in_format);
 
-const char *ofputil_packet_in_reason_to_string(enum ofp_packet_in_reason);
+enum { OFPUTIL_PACKET_IN_REASON_BUFSIZE = INT_STRLEN(int) + 1 };
+const char *ofputil_packet_in_reason_to_string(enum ofp_packet_in_reason,
+                                               char *reasonbuf,
+                                               size_t bufsize);
 bool ofputil_packet_in_reason_from_string(const char *,
                                           enum ofp_packet_in_reason *);