feature: default interface and basic start

.gitignore

@@ -1,2 +1,4 @@
 obj
 ft_nmap
+.cache
+compile_commands.json

Makefile

@@ -4,7 +4,7 @@ CC := gcc
 CFLAGS := -Wall -Wextra -Werror -iquoteinclude -g
 
 LD := $(CC)
-LDFLAGS := 
+LDFLAGS := -lpcap
 
 SRC := $(shell find src -name '*.c')
 OBJ := $(patsubst src/%.c,obj/%.o,$(SRC))

include/dns.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include <netinet/in.h>
+
+int dns_lookup(char *ip_addr, char *hostname, struct sockaddr_in *addr_con);
+int reverse_dns_lookup(char *ip_addr, char *host);

include/error.h

@@ -0,0 +1,3 @@
+#pragma once
+
+int err(char *str);

include/interface.h

@@ -0,0 +1,3 @@
+#pragma once
+
+char *get_interface_name(void);

include/print.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void print_usage(void);

include/scan.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <stdint.h>
+
+typedef enum {
+	SCAN_SYN,
+	SCAN_NULL,
+	SCAN_ACK,
+	SCAN_FIN,
+	SCAN_XMAS,
+	SCAN_UDP,
+	SCAN_TCP,
+} e_scantype;
+
+int routine(const char *ip_addr, e_scantype type, uint16_t min_port,
+            uint16_t max_port);

src/dns.c

@@ -0,0 +1,39 @@
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+
+int dns_lookup(char *ip_addr, char *hostname, struct sockaddr_in *addr_con)
+{
+	struct hostent *host = gethostbyname2(hostname, AF_INET);
+	if (!host) {
+		dprintf(2, "Hostname %s doesn't exist or has invalid format.",
+		        hostname);
+		return -1;
+	}
+	strcpy(ip_addr, inet_ntoa(*(struct in_addr *)host->h_addr));
+	(*addr_con).sin_family = host->h_addrtype;
+	(*addr_con).sin_port = htons(0);
+	(*addr_con).sin_addr.s_addr = *(long *)host->h_addr;
+
+	return 0;
+}
+
+int reverse_dns_lookup(char *ip_addr, char *host)
+{
+	struct sockaddr_in tmp_addr;
+
+	tmp_addr.sin_family = AF_INET;
+	tmp_addr.sin_addr.s_addr = inet_addr(ip_addr);
+	if (getnameinfo((struct sockaddr *)&tmp_addr,
+	                sizeof(struct sockaddr_in), host, NI_MAXHOST, NULL, 0,
+	                NI_NAMEREQD)) {
+		dprintf(2, "Could not resolve reverse lookup of %s\n", ip_addr);
+		return -1;
+	}
+
+	return 0;
+}

src/error.c

@@ -0,0 +1,9 @@
+#include <errno.h>
+#include <stdio.h>
+
+int err(char *str)
+{
+	int err = errno;
+	perror(str);
+	return err;
+}

src/get_interface.c

@@ -0,0 +1,24 @@
+#include <pcap.h>
+#include <string.h>
+
+char *get_interface_name(void)
+{
+	pcap_if_t *alldevs;
+	char errbuf[PCAP_ERRBUF_SIZE];
+
+	if (pcap_findalldevs(&alldevs, errbuf) == -1) {
+		dprintf(2, "Error finding devices: %s\n", errbuf);
+		return NULL;
+	}
+
+	for (pcap_if_t *it = alldevs; it != NULL; it = it->next) {
+		if (!(it->flags & PCAP_IF_LOOPBACK)) {
+			char *name = strdup(it->name);
+			pcap_freealldevs(alldevs);
+			return name;
+		}
+	}
+
+	dprintf(2, "No non-loopback interface found.\n");
+	return NULL;
+}

src/main.c

@@ -1,12 +1,35 @@
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <pcap.h>
 #include <stdio.h>
+#include <stdlib.h>
+
+#include "dns.h"
+#include "print.h"
+#include "scan.h"
 
 int main(int ac, char **av)
 {
-    (void) ac;
+	if (ac < 2) {
-    (void) av;
+		dprintf(2, "Usage: ft_nmap [Scan Type(s)] [Options] {target "
-    printf("%s %s\n",
+		           "specification}\n");
-           "gros gras grand grain d'orge, quand te dégros-gras-grand-grain-d'orgeras-tu ?",
+		print_usage();
-           "Je me dégros-gras-grand-grain-d'orgerai, quand tous les gros gras grains d'orge se seront dégros-gras-grand-grain- d'orgés.");
+		return 0;
+	}
+	// TODO parse arguments
+	(void)av;
 
-    return 0;
+	char ip_addr[INET_ADDRSTRLEN];
+	struct sockaddr_in addr_con;
+	if (dns_lookup(ip_addr, av[1], &addr_con)) {
+		dprintf(2, "ft_nmap: failed to retrieve ip address from %s\n",
+		        av[1]);
+		return 1;
+	}
+	if (routine(ip_addr, SCAN_SYN, 1, 1024) < 0) {
+		dprintf(2, "ft_nmap: failed to scan ports\n");
+		return 1;
+	}
+
+	return 0;
 }

src/print.c

@@ -0,0 +1,6 @@
+#include "print.h"
+
+void print_usage(void)
+{
+	// TODO print options list
+}

src/scan.c

@@ -0,0 +1,26 @@
+#include <netinet/in.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include "error.h"
+#include "interface.h"
+#include "scan.h"
+
+int routine(const char *ip_addr, e_scantype type, uint16_t min_port,
+            uint16_t max_port)
+{
+	int sockfd =
+	    socket(AF_INET, type == SCAN_UDP ? SOCK_DGRAM : SOCK_STREAM, 0);
+	if (sockfd < 0)
+		return err("Failed to create socket");
+
+	char *default_if = get_interface_name();
+	printf("%s\n", default_if);
+
+	(void)ip_addr;
+	for (int port = min_port; port <= max_port; port++) {
+		// scan(ip_addr, type, port);
+	}
+
+	return 0;
+}