chiark / gitweb /
site, transform: per-transform-instance max_start_pad
[secnet.git] / util.c
diff --git a/util.c b/util.c
index de91e1e..cfaefd2 100644 (file)
--- a/util.c
+++ b/util.c
@@ -38,6 +38,7 @@
 #include <sys/wait.h>
 #include "util.h"
 #include "unaligned.h"
+#include "magic.h"
 
 #define MIN_BUFFER_SIZE 64
 #define DEFAULT_BUFFER_SIZE 4096
@@ -246,6 +247,7 @@ void buffer_assert_used(struct buffer_if *buffer, cstring_t file,
 
 void buffer_init(struct buffer_if *buffer, int32_t max_start_pad)
 {
+    assert(max_start_pad<=buffer->len);
     buffer->start=buffer->base+max_start_pad;
     buffer->size=0;
 }
@@ -381,6 +383,38 @@ static list_t *buffer_apply(closure_t *self, struct cloc loc, dict_t *context,
     return new_closure(&st->cl);
 }
 
+void send_nak(const struct comm_addr *dest, uint32_t our_index,
+             uint32_t their_index, uint32_t msgtype,
+             struct buffer_if *buf, const char *logwhy)
+{
+    buffer_init(buf,dest->comm->min_start_pad);
+    buf_append_uint32(buf,their_index);
+    buf_append_uint32(buf,our_index);
+    buf_append_uint32(buf,LABEL_NAK);
+    if (logwhy)
+       Message(M_INFO,"%s: %08"PRIx32"<-%08"PRIx32": %08"PRIx32":"
+               " %s; sending NAK\n",
+               dest->comm->addr_to_string(dest->comm->st,dest),
+               our_index, their_index, msgtype, logwhy);
+    dest->comm->sendmsg(dest->comm->st, buf, dest);
+}
+
+int consttime_memeq(const void *s1in, const void *s2in, size_t n)
+{
+    const uint8_t *s1=s1in, *s2=s2in;
+    register volatile uint8_t accumulator=0;
+
+    while (n-- > 0) {
+       accumulator |= (*s1++ ^ *s2++);
+    }
+    accumulator |= accumulator >> 4; /* constant-time             */
+    accumulator |= accumulator >> 2; /*  boolean canonicalisation */
+    accumulator |= accumulator >> 1;
+    accumulator &= 1;
+    accumulator ^= 1;
+    return accumulator;
+}
+
 void util_module(dict_t *dict)
 {
     add_closure(dict,"sysbuffer",buffer_apply);