1 files changed, 65 insertions, 0 deletions

diff --git a/src/ot_scan.c b/src/ot_scan.c
new file mode 100644
index 0000000..3b8e87c
--- /dev/null
+++ b/src/ot_scan.c
@@ -0,0 +1,65 @@
+/* This software was written by Dirk Engling <erdgeist@erdgeist.org>
+   It is considered beerware. Prost. Skol. Cheers or whatever. */
+
+/* System */
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/* Opentracker */
+#include "ot_scan.h"
+
+size_t scan_uint(const char *src, uint64_t *dest, uint64_t max) {
+  unsigned long long value;
+  char              *end;
+
+  if (*src < '0' || *src > '9')
+    return 0;
+
+  errno = 0;
+  value = strtoull(src, &end, 10);
+
+  if (errno == ERANGE || value > (unsigned long long)max)
+    return 0;
+
+  *dest = (uint64_t)value;
+  return (size_t)(end - src);
+}
+
+size_t scan_uint_bencode(const char *src, uint64_t *dest, uint64_t max) {
+  uint64_t value;
+  size_t   consumed = scan_uint(src, &value, max);
+
+  /* bencode writes no leading zeros, so anything longer than a single digit
+     must not begin with one. */
+  if (consumed > 1 && *src == '0')
+    return 0;
+
+  if (consumed)
+    *dest = value;
+
+  return consumed;
+}
+
+int scan_int(const char *src, size_t len, int64_t *dest) {
+  int64_t value  = 0;
+  int     negate = 0;
+
+  if (len && *src == '-')
+    --len, ++src, negate = 1;
+  if (!len)
+    return -1;
+
+  while (len--) {
+    if (*src < '0' || *src > '9')
+      return -1;
+    /* A twenty character field of nines does not fit, and silently wrapping
+       would magically heal a nonsense announce */
+    if (value > (INT64_MAX - (*src - '0')) / 10)
+      return -1;
+    value = 10 * value + (*src++ - '0');
+  }
+
+  *dest = negate ? -value : value;
+  return 0;
+}