Add C source file

5 years ago · 8a1893a7f9
parent 7a85d6546b
commit 8a1893a7f9
1 changed files with 258 additions and 0 deletions
--- a/subnetting.c
+++ b/subnetting.c
@ -0,0 +1,258 @@
+#include <stdio.h>
+#include <math.h>
+#include <string.h>
+#include <stdbool.h>
+
+enum NetworkClass {CLASS_A, CLASS_B, CLASS_C};
+
+// This section of code consitutes a more Java-like version of finding a preix
+// A C programmer is more likely to simply do the binary math.
+const unsigned int prefix_map[9] = {0, 128, 192, 224, 240, 248, 252, 254, 255};
+const int usable_hosts_map[9] = {254, 126, 62, 30, 14, 6, 2, 0, 0};
+const int subnet_multiplyer[4] = {0, 8, 16, 24};
+
+unsigned int* subnet_to_octet_array(unsigned int octets[4], char subnet_mask[16]){
+	sscanf(subnet_mask, "%u.%u.%u.%u", &octets[0], &octets[1], &octets[2], &octets[3]);
+	return octets;
+}
+
+int mask_to_prefix(char mask[16]){
+	unsigned int octet[4];
+	int pref = 0;
+	subnet_to_octet_array(octet, mask);
+	for (int i = 0; i < 4; ++i){
+		for (int j = 0; j < 9; ++j){
+			if (octet[i] == prefix_map[j]){
+				pref += j;
+				break;
+			}
+		}
+	}
+	return pref;
+}
+
+char* prefix_to_mask(char subnet_mask[16], unsigned int prefix){
+	unsigned int octets[5];
+	for (int i = 0; i < 5; ++i){
+		for (int j = 8; j >= 0; --j){
+			if (prefix >= j){
+				prefix -= j;
+				octets[i] = prefix_map[j];
+				break;
+			}
+		}
+	}
+	sprintf(subnet_mask, "%u.%u.%u.%u", octets[0], octets[1], octets[2], octets[3]);
+	return subnet_mask;
+}
+
+int hosts_for_prefix(int prefix){
+	return (int)pow(2.0, (double)(32-prefix));
+}
+
+int subnets_for_prefix(int prefix){
+	return (int)pow(2.0, (double)(prefix%8));
+}
+
+void ui_to_octets(char addr[16], unsigned int subnet_mask){
+	int octets[4];
+	octets[0] = (subnet_mask >> 24) & 0xFF;
+	octets[1] = (subnet_mask >> 16) & 0xFF;
+	octets[2] = (subnet_mask >> 8) & 0xFF;
+	octets[3] = subnet_mask & 0xFF;
+	sprintf(addr, "%d.%d.%d.%d", octets[0], octets[1], octets[2], octets[3]);
+}	
+
+int prefix_for_hosts(int hosts_required){
+	for (int i = 32; i >= 0; --i){
+		if (hosts_for_prefix(i)-2 >= hosts_required){
+			return i;
+		}
+	}
+	return -1;
+}
+
+char* octet_array_to_string(char subnet_mask[16], char octets[4]){
+	sprintf(subnet_mask, "%d.%d.%d.%d", octets[0], octets[1], octets[2], octets[3]);
+	return subnet_mask;
+}
+
+int network_type_based_on_subnet(int subnet_arr[4]){
+	if (subnet_arr[0] != 255){
+		return -1;
+	} else if (subnet_arr[1] != 255){
+		return CLASS_A;
+	} else if (subnet_arr[2] != 255){
+		return CLASS_B;
+	} else if (subnet_arr[3] != 255){
+		return CLASS_C;
+	} else {
+		return -1;
+	}
+}
+
+char network_class(int subnet_arr[4]){
+	if (subnet_arr[0] != 255){
+		return '?';
+	} else if (subnet_arr[1] != 255){
+		return 'A';
+	} else if (subnet_arr[2] != 255){
+		return 'B';
+	} else if (subnet_arr[3] != 255){
+		return 'C';
+	} else {
+		return '?';
+	}
+}
+
+unsigned int octets_to_ui(char octets[16]){
+	int so_s[4];
+	unsigned int rv;
+	sscanf(octets, "%d.%d.%d.%d", &so_s[0], &so_s[1], &so_s[2], &so_s[3]);
+	rv = (so_s[0] << 24) | (so_s[1] << 16) | (so_s[2] << 8) | (so_s[3]);
+	return rv;
+}
+
+unsigned int bdr_addr(unsigned int ip, unsigned int subnet){
+	return ip | ~subnet;
+}
+unsigned int net_addr(unsigned int ip, unsigned int subnet){
+	return ip & subnet;
+}
+
+char* network_address(char result[16], char ip[16], char subnet[16]){
+	unsigned int num = octets_to_ui(ip) & octets_to_ui(subnet);
+	ui_to_octets(result, num);
+	return result;
+}
+char* broadcast_address(char result[16], char ip[16], char subnet[16]){
+	unsigned int bdr_add = octets_to_ui(ip) | ~octets_to_ui(subnet);
+	ui_to_octets(result, bdr_add);
+	return result;
+}
+
+
+char* usable_host_addresses(char result[33], char ip[16], char subnet[16]){
+	char slow_addrs[16];
+	char shigh_addrs[16];
+	unsigned int low_addr = net_addr(octets_to_ui(ip), octets_to_ui(subnet));
+	unsigned int high_addr = bdr_addr(octets_to_ui(ip), octets_to_ui(subnet));
+
+	++low_addr;
+	--high_addr;
+
+	ui_to_octets(slow_addrs, low_addr);
+	ui_to_octets(shigh_addrs, high_addr);
+	sprintf(result, "%s-%s", slow_addrs, shigh_addrs);
+	return result;
+}
+
+int get_ui_class(unsigned int ip){
+	unsigned int fo = ip >> 24;
+	if (fo >= 1 && fo <= 126){
+		return CLASS_A;
+	} else if (fo >= 128 && fo <= 191){
+		return CLASS_B;
+	} else if (fo >= 192 && fo <= 223){
+		return CLASS_C;
+	}
+	return -1;
+}
+
+int main(){
+	char* mask1 = {"255.255.255.192"};
+	char mask2[16];
+	int prefix, hosts, networks;
+	unsigned int octets[4];
+
+	prefix = mask_to_prefix(mask1);
+	fprintf(stdout, "Prefix of %s is %d\n", mask1, prefix);
+	prefix_to_mask(mask2, prefix);
+	fprintf(stdout, "Subnet of %d is %s\n", prefix, mask2);
+	hosts = hosts_for_prefix(prefix);
+	printf("It can support up to %d hosts.\n", hosts);
+	networks = subnets_for_prefix(prefix);
+	printf("It can support ip to %d subnets.\n", networks);
+	subnet_to_octet_array(octets, mask1);
+	for (int i = 0; i < 4; ++i){
+		printf("\tPt %d: %d\n", i+1, octets[i]);
+	}
+
+	int prefix64,prefix2000;
+	char subnet64[16];
+	char subnet2000[16];
+
+	int subarr64[4];
+	int subarr2000[4];
+
+	prefix64 = prefix_for_hosts(64);
+	prefix2000 = prefix_for_hosts(2000);
+	prefix_to_mask(subnet64, prefix64);
+	prefix_to_mask(subnet2000, prefix2000);
+	subnet_to_octet_array(subarr64, subnet64);
+	subnet_to_octet_array(subarr2000, subnet2000);
+	printf("64 hosts requires a prefix of %d (%s).\n", prefix64, subnet64);
+	printf("2000 hosts requires a prefix of %d (%s).\n", prefix2000, subnet2000);
+	printf("A prefix of %d can support %d hosts.\n", prefix2000, hosts_for_prefix(prefix2000));
+	printf("%s indicates a class %c network.\n", subnet64, network_class(subarr64));
+	printf("%s indicates a class %c network.\n", subnet2000, network_class(subarr2000));
+	
+
+	char* ip1 = {"192.168.16.122"};
+	char* sub1_ip1 = { "255.255.255.240" };
+	char na_ip1[16];
+	char ba_ip1[16];
+	char ra_ip1[33];
+	network_address(na_ip1, ip1, sub1_ip1);
+	broadcast_address(ba_ip1, ip1, sub1_ip1);
+	usable_host_addresses(ra_ip1, ip1, sub1_ip1);
+	printf("%s (%s)'s network address is %s.\n", ip1, sub1_ip1, na_ip1);
+	printf("%s (%s)'s broadcast address is %s.\n", ip1, sub1_ip1, ba_ip1);
+	printf("The host range is %s\n", ra_ip1);
+	char* ip2 = {"172.17.130.222"};
+	char* sub2_ip2 = { "255.255.128.0" };
+	char na_ip2[16];
+	network_address(na_ip2, ip2, sub2_ip2);
+	printf("%s (%s)'s network address is %s.\n", ip2, sub2_ip2, na_ip2);
+
+	// actual program
+	char* print_format = {"%18s | %33s | %18s | %16s | /%2d\n"};
+	int num_of_networks;
+	int hosts_per_network;
+	char file_location[255];
+	FILE* print_file;
+	printf("Where would you like to save these tables? ");
+	scanf("%s", file_location);
+	print_file = fopen(file_location, "w");
+	fprintf(print_file, "---------------------------------------------------------------------------------------------------------------------\n");
+	printf("How many networks do you need? ");
+	scanf("%d", &num_of_networks);
+	char ip[16];
+	unsigned int ui_ip;
+
+	printf("Enter a base IP address to start configuring. (Usually 192.168.x.0, 172.17.x.0, etc...)\nBase IP: ");
+	scanf("%s", ip);
+	ui_ip = octets_to_ui(ip);
+	fprintf(print_file, print_format, "Network Address", "Host Range", "Broadcast Address", "Subnet Mask", 0);
+	for (int i = 0; i < num_of_networks; ++i){
+		int hosts;
+		char subnt_s[16];
+		char broadcast_addr[16];
+		char network_addr[16];
+		char usable_range[33];
+		unsigned int subnt;
+		int this_prefix;
+		printf("How many hosts do you need on this network [%d]? ", i);
+		scanf("%d", &hosts);
+		this_prefix = prefix_for_hosts(hosts);
+		prefix_to_mask(subnt_s, this_prefix);
+		subnt = octets_to_ui(subnt_s);
+		broadcast_address(broadcast_addr, ip, subnt_s);
+		network_address(network_addr, ip, subnt_s);
+		usable_host_addresses(usable_range, ip, subnt_s);
+		fprintf(print_file, print_format, network_addr, usable_range, broadcast_addr, subnt_s, this_prefix);
+		ui_ip = octets_to_ui(broadcast_addr) + 1;	
+		ui_to_octets(ip, ui_ip);
+	}
+	return 0;
+}