From b6574898519ef89d5481ad677347f0630c877561 Mon Sep 17 00:00:00 2001
From: Joel Grunbaum <joelgrun@gmail.com>
Date: Tue, 20 Oct 2020 13:29:13 +0000
Subject: [PATCH] Specify number of serves and hosts, test and sort servers

---
 /dev/null       |   61 ------------
 slist.c         |  137 +++++++++++++++++++++++++++
 Makefile        |    4 
 main.c          |   91 ++++++++++--------
 include/slist.h |    2 
 5 files changed, 191 insertions(+), 104 deletions(-)

diff --git a/Makefile b/Makefile
index d0e275b..c67c988 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CC=gcc
-_OBJ=main.o dns.o servers.o
-_DEPS=dns.h servers.h
+_OBJ=main.o dns.o slist.o
+_DEPS=dns.h servers.h slist.h
 IDIR=include
 CFLAGS=-I$(IDIR) -Wall -g
 ODIR=obj
diff --git a/include/slist.h b/include/slist.h
index fc12640..2533c33 100644
--- a/include/slist.h
+++ b/include/slist.h
@@ -15,3 +15,5 @@
 int free_hosts_list(struct hosts_list **head);
 int add_dns_server(struct dns_list **head, char *server);
 int free_dns_list(struct dns_list **head);
+int sort_servers(struct dns_list **headRef);
+int print_servers(struct dns_list *head);
diff --git a/main.c b/main.c
index 009234a..3db7eee 100644
--- a/main.c
+++ b/main.c
@@ -9,78 +9,87 @@
 
 #define NUM_TESTS 10
 
-struct timespec test_server(char *dns_addr, struct hosts_list *hosts);
+int test_dns(struct dns_list *dnss, struct hosts_list *hosts, int num_hosts, int num_tests);
+struct timespec test_server(struct dns_list *dns, struct hosts_list *hosts, int num_hosts, int num_tests);
 
 int main(int argc, char** argv)
 {
-	int option, type = T_A;
-	char* server = "1.1.1.1", *hostname = "google.com";
+	int option, num_hosts = 0, added_hosts = 0, num_tests = NUM_TESTS;
 	struct hosts_list *servers_hosts = NULL;
 	struct dns_list *servers_dns = NULL;
-	while((option = getopt(argc, argv, "s:h:t:")) != -1) {
+	while((option = getopt(argc, argv, "s:h:t:n:")) != -1) {
 		switch (option) {
 		case 's': //server to use
 			add_dns_server(&servers_dns, optarg);
 			break;
 		case 'h': //hostname to search
 			add_hosts_server(&servers_hosts, optarg);
+			added_hosts++;
 			break;
-		case 't':
-			if (!strcmp(optarg, "A")) {
-				type = T_A;
-			} else if (!strcmp(optarg, "AAAA")) {
-				type = T_AAAA;
-			} else if (!strcmp(optarg, "NS")) {
-				type = T_NS;
-			} else if (!strcmp(optarg, "CNAME")) {
-				type = T_CNAME;
-			} else if (!strcmp(optarg, "SOA")) {
-				type = T_SOA;
-			} else if (!strcmp(optarg, "PTR")) {
-				type = T_PTR;
-			} else if (!strcmp(optarg, "MX")) {
-				type = T_MX;
-			} else if (!strcmp(optarg, "TXT")) {
-				type = T_TXT;
-			} else {
-				printf("Error: %s is not a valid DNS record type\n", optarg);
-				free_hosts_list(&servers_hosts);
-				free_dns_list(&servers_dns);
-				exit(1);
-			}
+		case 't': //set number of hosts to test
+			num_hosts = atoi(optarg);
+			break;
+		case 'n': //number of tests to perform
+			num_tests = atoi(optarg);
 			break;
 		case '?':
 		default:
 			printf("Error: invalid option -%c\n", optopt);
+			free_dns_list(&servers_dns);
+			free_hosts_list(&servers_hosts);
 			exit(1);
 		}
 	}
-	struct timespec total;
-	total = test_server(server, servers_hosts);
-	printf("Test took %ld.%09lds\n", total.tv_sec, total.tv_nsec);
+	if (num_hosts == 0 || num_hosts > NUM_HOSTNAMES+added_hosts) {
+		num_hosts = NUM_HOSTNAMES + added_hosts;
+	}
+	for (int i = added_hosts; i < num_hosts; i++) {
+		add_hosts_server(&servers_hosts, HOSTNAMES[i-added_hosts]);
+	}
+	for (int i = 0; i < NUM_DNS; i++) {
+		add_dns_server(&servers_dns, DNS_SERVERS[i]);
+	}
+	test_dns(servers_dns, servers_hosts, num_hosts, num_tests);
+	sort_servers(&servers_dns);
+	print_servers(servers_dns);
 	free_dns_list(&servers_dns);
 	free_hosts_list(&servers_hosts);
 	return 0;
 }
 
-struct timespec test_server(char* dns_addr, struct hosts_list *hosts)
+int test_dns(struct dns_list *dnss, struct hosts_list *hosts, int num_hosts, int num_tests)
 {
-	struct timespec total;
-	total.tv_sec = 0; total.tv_nsec = 0;
-	for (int i = 0; i < NUM_TESTS; i++) {
+	struct dns_list *curr = dnss;
+	while (curr) {
+		test_server(curr, hosts, num_hosts, num_tests);
+		curr = curr->next;
+	}
+	return 0;
+}
+
+struct timespec test_server(struct dns_list *dns, struct hosts_list *hosts, int num_hosts, int num_tests)
+{
+	unsigned long long avg_nsec = 0;
+	dns->time.tv_sec = 0; dns->time.tv_nsec = 0;
+	for (int i = 0; i < num_tests; i++) {
 		struct hosts_list *curr = hosts;
 		while (curr) {
 			struct timespec run;
 			unsigned char buf[65536];
-			run = resolve(buf, curr->server, dns_addr, T_A);
-			total.tv_sec += run.tv_sec;
-			total.tv_nsec += run.tv_nsec;
-			if (total.tv_nsec >= 1000000000) {
-				total.tv_sec += 1;
-				total.tv_nsec -= 1000000000;
+			run = resolve(buf, curr->server, dns->server, T_A);
+			if (run.tv_sec == -1)
+				continue;
+			dns->time.tv_sec += run.tv_sec;
+			dns->time.tv_nsec += run.tv_nsec;
+			if (dns->time.tv_nsec >= 1000000000) {
+				dns->time.tv_sec += 1;
+				dns->time.tv_nsec -= 1000000000;
 			}
 			curr = curr->next;
 		}
 	}
-	return total;
+	avg_nsec = 1000000000*(dns->time.tv_sec%(num_hosts*num_tests))+dns->time.tv_nsec;
+	dns->time.tv_sec = dns->time.tv_sec/(num_hosts*num_tests);
+	dns->time.tv_nsec = avg_nsec/(num_hosts*num_tests);
+	return dns->time;
 }
diff --git a/servers.c b/servers.c
deleted file mode 100644
index 3e2d918..0000000
--- a/servers.c
+++ /dev/null
@@ -1,61 +0,0 @@
-#include <stdlib.h>
-#include "slist.h"
-
-int add_hosts_server(struct hosts_list **head, char *server)
-{
-	 struct hosts_list *end;
-	 if (!(*head)) {
-		  *head = malloc(sizeof(struct hosts_list));
-		  end = *head;
-	 } else {
-		  end = *head;
-		  while (end->next)
-			   end = end->next;
-		  end->next = malloc(sizeof(struct hosts_list));
-		  end = end->next;
-	 }
-	 end->next = NULL;
-	 end->server = server;
-	 return 0;
-}
-
-int free_hosts_list(struct hosts_list **head)
-{
-	 struct hosts_list *temp;
-	 while (*head) {
-		  temp = (*head)->next;
-		  free(*head);
-		  *head = temp;
-	 }
-	 return 0;
-}
-
-int add_dns_server(struct dns_list **head, char* server)
-{
-	 struct dns_list *end;
-	 if (!(*head)) {
-		  *head = malloc(sizeof(struct dns_list));
-		  end = *head;
-	 } else {
-		  end = *head;
-		  while (end->next)
-			   end = end->next;
-		  end->next = malloc(sizeof(struct dns_list));
-		  end = end->next;
-	 }
-	 end->next = NULL;
-	 end->server = server;
-	 end->time.tv_nsec = 0; end->time.tv_sec = 0;
-	 return 0;
-}
-
-int free_dns_list(struct dns_list **head)
-{
-	 struct dns_list *temp;
-	 while (*head) {
-		  temp = (*head)->next;
-		  free(*head);
-		  *head = temp;
-	 }
-	 return 0;
-}
diff --git a/slist.c b/slist.c
new file mode 100644
index 0000000..7aa0413
--- /dev/null
+++ b/slist.c
@@ -0,0 +1,137 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "slist.h"
+
+void split(struct dns_list *head, struct dns_list **a, struct dns_list **b);
+struct dns_list *merge(struct dns_list *a, struct dns_list *b);
+int comp_times(struct timespec a, struct timespec b);
+
+int add_hosts_server(struct hosts_list **head, char *server)
+{
+	 struct hosts_list *end;
+	 if (!(*head)) {
+		  *head = malloc(sizeof(struct hosts_list));
+		  end = *head;
+	 } else {
+		  end = *head;
+		  while (end->next)
+			   end = end->next;
+		  end->next = malloc(sizeof(struct hosts_list));
+		  end = end->next;
+	 }
+	 end->next = NULL;
+	 end->server = server;
+	 return 0;
+}
+
+int free_hosts_list(struct hosts_list **head)
+{
+	 struct hosts_list *temp;
+	 while (*head) {
+		  temp = (*head)->next;
+		  free(*head);
+		  *head = temp;
+	 }
+	 return 0;
+}
+
+int add_dns_server(struct dns_list **head, char* server)
+{
+	 struct dns_list *end;
+	 if (!(*head)) {
+		  *head = malloc(sizeof(struct dns_list));
+		  end = *head;
+	 } else {
+		  end = *head;
+		  while (end->next)
+			   end = end->next;
+		  end->next = malloc(sizeof(struct dns_list));
+		  end = end->next;
+	 }
+	 end->next = NULL;
+	 end->server = server;
+	 end->time.tv_nsec = 0; end->time.tv_sec = 0;
+	 return 0;
+}
+
+int free_dns_list(struct dns_list **head)
+{
+	 struct dns_list *temp;
+	 while (*head) {
+		  temp = (*head)->next;
+		  free(*head);
+		  *head = temp;
+	 }
+	 return 0;
+}
+
+int sort_servers(struct dns_list **headRef)
+{
+	struct dns_list *head = *headRef;
+	struct dns_list *a, *b;
+	if (!head || !(head->next)) { //Empty list or containing one element
+		return 0;
+	}
+	split(head, &a, &b);
+	sort_servers(&a);
+	sort_servers(&b);
+	*headRef = merge(a, b);
+	return 0;
+}
+
+void split(struct dns_list *head, struct dns_list **a, struct dns_list **b)
+{
+	struct dns_list *fast = head->next, *slow = head;
+	while(fast) {
+		fast = fast->next;
+		if (fast) {
+			slow = slow->next;
+			fast = fast->next;
+		}
+	}
+	*a = head;
+	*b = slow->next;
+	slow->next = NULL;
+}
+
+struct dns_list *merge(struct dns_list *a, struct dns_list *b)
+{
+	struct dns_list *out = NULL;
+	int comp;
+	if (!a)
+		return b;
+	if (!b)
+		return a;
+
+	if (comp_times(a->time, b->time) > 0) {
+		out = b;
+		out->next = merge(a, b->next);
+	} else {
+		out = a;
+		out->next = merge(a->next, b);
+	}
+	return out;
+}
+
+int comp_times(struct timespec a, struct timespec b)
+{
+	if (a.tv_sec == b.tv_sec) {
+		if (a.tv_nsec >= b.tv_nsec)
+			return 1;
+		else
+			return -1;
+	} else if (a.tv_sec > b.tv_sec) {
+		return 1;
+	} else
+		return -1;
+}
+
+int print_servers(struct dns_list *head)
+{
+	printf("%-20s | %s\n", "Server", "Time");
+	while (head) {
+		printf("%-20s | %ld.%09ld\n", head->server, head->time.tv_sec, head->time.tv_nsec);
+		head = head->next;
+	}
+	return 0;
+}

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