From ae035800d37ad4602606ff5291b279fe94cc8a6a Mon Sep 17 00:00:00 2001
From: 0x1eef <0x1eef@protonmail.com>
Date: Wed, 20 Sep 2023 05:42:02 -0300
Subject: [PATCH] Add isinetaddr4.c improvements

---
 src/isinetaddr4.c | 58 +++++++++++++++++++----------------------------
 1 file changed, 23 insertions(+), 35 deletions(-)

diff --git a/src/isinetaddr4.c b/src/isinetaddr4.c
index 1945865..0417ba1 100644
--- a/src/isinetaddr4.c
+++ b/src/isinetaddr4.c
@@ -4,66 +4,54 @@
 #include <isinetaddr.h>
 #include <errno.h>
 
-static int in_range(char buf[4], int min, int max);
-static void register_octet(int *octets, char *buf, int *buflen);
-static void register_digit(char digit, int *digits, char *buf, int *buflen);
+static const int  MAX_BUFLEN   = 3;
+static const int  MAX_OCTETS   = 4;
+static const int  MAX_DIGITLEN = 12;
+static const int  MAX_STRLEN   = 16;
+static const char SEP = '.';
+
+static int in_range(char buf[MAX_BUFLEN]);
 
 int
 isinetaddr4(const char *str)
 {
-  char buf[4];
+  char buf[MAX_BUFLEN + 1];
   int digits = 0, octets = 1, buflen = 0;
-  size_t len = (str == NULL ? 0 : strnlen(str, 16));
+  size_t len = (str == NULL ? 0 : strnlen(str, MAX_STRLEN));
 
+  buf[MAX_BUFLEN] = '\0';
   for (size_t l = 0; l < len; l++) {
-    if (str[l] == '.') {
+    if (str[l] == SEP) {
       if (buflen == 0) {
         return 0;
-      } else if (!in_range(buf, 0, 255)) {
+      } else if (!in_range(buf)) {
         return 0;
       } else {
-        register_octet(&octets, buf, &buflen);
+        buflen = 0;
+        bzero(buf, MAX_BUFLEN);
+        octets++;
       }
     } else if (isdigit(str[l])) {
-      if (buflen == 3) {
+      if (buflen == MAX_BUFLEN) {
         return 0;
       } else {
-        register_digit(str[l], &digits, buf, &buflen);
+        buf[buflen++] = str[l];
+        digits++;
       }
     } else {
       return 0;
     }
   }
-  if (octets == 4) {
-    return buflen > 0 && digits <= 12 && in_range(buf, 0, 255);
+  if (octets == MAX_OCTETS) {
+    return digits <= MAX_DIGITLEN && buflen > 0 && in_range(buf);
   } else {
     return 0;
   }
 }
 
 static int
-in_range(char buf[4], int min, int max)
+in_range(char buf[MAX_BUFLEN])
 {
-  char *err;
-  long r;
-  errno = 0;
-  r = strtol(buf, &err, 10);
-  return *err == '\0' && errno == 0 && (r >= min && r <= max);
-}
-
-static void
-register_octet(int *octets, char *buf, int *buflen)
-{
-  *buflen = 0;
-  (*octets)++;
-  bzero(buf, 3);
-  buf[3] = '\0';
-}
-
-static void
-register_digit(char digit, int *digits, char *buf, int *buflen)
-{
-  buf[(*buflen)++] = digit;
-  buf[*buflen] = '\0';
-  (*digits)++;
+  int n = atoi(buf);
+  return n >= 0 && n <= 255;
 }