Add validate-ip-address

Author: anvouk

CMakeLists.txt

@@ -5,3 +5,4 @@ add_subdirectory(letter-comb)
 add_subdirectory(lgc)
 add_subdirectory(parentheses)
 add_subdirectory(remove-duplicates-from-sorted)
+add_subdirectory(validate-ip)

validate-ip/CMakeLists.txt

@@ -0,0 +1,3 @@
+set(CMAKE_C_STANDARD 99)
+
+add_executable(validate-ip main.c)

validate-ip/main.c

@@ -0,0 +1,177 @@
+#include <ctype.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+/**
+ * Convert a string to an uint8 or return error.
+ * @note Does not check if input string is made only of valid numbers but checks
+ * for leading zeros, which are treated as an error.
+ * @param str Valid number as string.
+ * @return -1 on error, a num castable to uint8 otherwise.
+ */
+static int strtou8(const char *str)
+{
+    if (strlen(str) == 0) {
+        return -1;
+    }
+    // no leading zeros are allowed.
+    if (*str == '0' && *(str + 1) != '\0') {
+        return -1;
+    }
+
+    char len = (char)strlen(str);
+    int res = 0;
+    int pos = 1;
+    for (int i = 0; i < len - 1; ++i) {
+        pos *= 10;
+    }
+    for (const char *c = str; *c != '\0'; ++c, pos /= 10) {
+        res += (*c - '0') * pos;
+    }
+    if (res < 0 || res > 255) {
+        return -1;
+    }
+    return res;
+}
+
+static bool validateIpv4(const char *queryIP)
+{
+    char ip[4][4] = { 0 };
+    char ip_num_idx = 0;
+    char ip_num_str_idx = 0;
+    for (const char *c = queryIP; *c != '\0'; ++c) {
+        if (*c == '.') {
+            ++ip_num_idx;
+            ip_num_str_idx = 0;
+
+            // too many dots: invalid ipv4
+            if (ip_num_idx > 3) {
+                return false;
+            }
+            continue;
+        }
+        // not a digit other than dots: invalid ipv4
+        if (!isdigit(*c)) {
+            return false;
+        }
+
+        // u8 biggest char count is (255): invalid ipv4 otherwise.
+        if (ip_num_str_idx >= 3) {
+            return false;
+        }
+
+        ip[ip_num_idx][ip_num_str_idx++] = *c;
+    }
+
+    for (char i = 0; i < 4; ++i) {
+        if (strtou8(ip[i]) == -1) {
+            return false;
+        }
+    }
+    return true;
+}
+
+static bool isHex(char ch)
+{
+    if (isdigit(ch)) {
+        return true;
+    }
+
+    switch (ch) {
+    case 'a':
+    case 'b':
+    case 'c':
+    case 'd':
+    case 'e':
+    case 'f':
+    case 'A':
+    case 'B':
+    case 'C':
+    case 'D':
+    case 'E':
+    case 'F':
+        return true;
+    default:
+        return false;
+    }
+}
+
+static bool validateIpv6(const char *queryIP)
+{
+    char ip[8][5] = { 0 };
+    char ip_num_idx = 0;
+    char ip_num_str_idx = 0;
+    for (const char *c = queryIP; *c != '\0'; ++c) {
+        if (*c == ':') {
+            ++ip_num_idx;
+            ip_num_str_idx = 0;
+
+            // too many dots: invalid ipv6
+            if (ip_num_idx > 7) {
+                return false;
+            }
+            continue;
+        }
+        // not a digit other than dots: invalid ipv4
+        if (!isHex(*c)) {
+            return false;
+        }
+
+        // too many chars for num: invalid ipv4 otherwise.
+        if (ip_num_str_idx >= 4) {
+            return false;
+        }
+
+        ip[ip_num_idx][ip_num_str_idx++] = *c;
+    }
+
+    for (char i = 0; i < 8; ++i) {
+        if (strlen(ip[i]) < 1) {
+            return false;
+        }
+    }
+    return true;
+}
+
+char *validIPAddress(char *queryIP)
+{
+    for (char *c = queryIP; *c != '\0'; ++c) {
+        switch (*c) {
+        case '.':
+            if (validateIpv4(queryIP)) {
+                return "IPv4";
+            }
+            return "Neither";
+        case ':':
+            if (validateIpv6(queryIP)) {
+                return "IPv6";
+            }
+            return "Neither";
+        }
+    }
+    return "Neither";
+}
+
+static void test(const char *ip)
+{
+    printf("ip: %-40s | res: %s\n", ip, validIPAddress(ip));
+}
+
+/* https://leetcode.com/problems/validate-ip-address/ */
+int main(void)
+{
+    test("1.0.1.");
+    test("192.168.30.0");
+    test("192.168.01.1");
+    test("192.168.01.");
+    test("0.168.30.1");
+    test("192.101.30.1");
+    test("192.1013.30.1");
+    test("192.101.30.1422");
+    test("192.101..142");
+
+    test("2001:0db8:85a3:0:0:8A2E:0370:7334");
+    test("2001:0db8:85a3::0:8A2E:0370:7334");
+    return 0;
+}