fixes #686 strtoull() not present on Windows

This both makes new functions available to the core,
and addresses a bug which would have prevented building the
ZeroTier transport on Windows.

3 files changed, 77 insertions, 3 deletions

diff --git a/src/core/strs.c b/src/core/strs.c
index 98c1a5fa..ed403a3b 100644
--- a/src/core/strs.c
+++ b/src/core/strs.c
@@ -202,3 +202,77 @@ nni_asprintf(char **sp, const char *fmt, ...)
 	*sp = s;
 	return (0);
 }
+
+int
+nni_strtou64(const char *s, uint64_t *u)
+{
+	uint64_t v = 0;
+
+	// Arguably we could use strtoull, but Windows doesn't conform
+	// to C99, and so lacks it.
+
+	if ((s == NULL) || (*s == '\0')) {
+		// Require a non-empty string.
+		return (NNG_EINVAL);
+	}
+	while (*s) {
+		uint64_t last = v;
+		if (isdigit(*s)) {
+			v *= 10;
+			v += (*s - '0');
+		} else {
+			return (NNG_EINVAL);
+		}
+		if (v < last) {
+			// Overflow!
+			return (NNG_EINVAL);
+		}
+		s++;
+	}
+	*u = v;
+	return (0);
+}
+
+int
+nni_strtox64(const char *s, uint64_t *u)
+{
+	uint64_t v = 0;
+
+	// Arguably we could use strtoull, but Windows doesn't conform
+	// to C99, and so lacks it.
+
+	if (s == NULL) {
+		return (NNG_EINVAL);
+	}
+	// Skip over 0x if present.
+	if ((s[0] == '0') && ((s[1] == 'x') || (s[1] == 'X'))) {
+		s += 2;
+	}
+	if (*s == '\0') {
+		// Require a non-empty string.
+		return (NNG_EINVAL);
+	}
+
+	while (*s) {
+		uint64_t last = v;
+		if (isdigit(*s)) {
+			v *= 16;
+			v += (*s - '0');
+		} else if ((*s >= 'a') && (*s <= 'f')) {
+			v *= 16;
+			v += (*s - 'a') + 10;
+		} else if ((*s >= 'A') && (*s <= 'F')) {
+			v *= 16;
+			v += (*s - 'A') + 10;
+		} else {
+			return (NNG_EINVAL);
+		}
+		if (v < last) {
+			// Overflow!
+			return (NNG_EINVAL);
+		}
+		s++;
+	}
+	*u = v;
+	return (0);
+}
diff --git a/src/core/strs.h b/src/core/strs.h
index d4851ecf..4ed1fb57 100644
--- a/src/core/strs.h
+++ b/src/core/strs.h
@@ -22,5 +22,7 @@ extern char * nni_strcasestr(const char *, const char *);
 extern int    nni_strncasecmp(const char *, const char *, size_t);
 extern int    nni_strcasecmp(const char *, const char *);
 extern int    nni_asprintf(char **, const char *, ...);
+extern int    nni_strtou64(const char *, uint64_t *); // parses decimal
+extern int    nni_strtox64(const char *, uint64_t *); // parses hex
 
 #endif // CORE_STRS_H
diff --git a/src/transport/zerotier/zerotier.c b/src/transport/zerotier/zerotier.c
index 0b0303d9..95fedc0d 100644
--- a/src/transport/zerotier/zerotier.c
+++ b/src/transport/zerotier/zerotier.c
@@ -1529,14 +1529,12 @@ zt_walk_moons(const char *path, void *arg)
 {
 	zt_node *   ztn = arg;
 	const char *bn  = nni_file_basename(path);
-	char *      ep;
 	uint64_t    moonid;
 
 	if (strncmp(bn, "moon.", 5) != 0) {
 		return (NNI_FILE_WALK_CONTINUE);
 	}
-	moonid = strtoull(bn + 5, &ep, 16);
-	if (*ep == '\0') {
+	if (nni_strtox64(bn + 5, &moonid) == 0) {
 		ZT_Node_orbit(ztn->zn_znode, NULL, moonid, 0);
 	}
 	return (NNI_FILE_WALK_CONTINUE);