1 files changed, 159 insertions, 143 deletions

diff --git a/main.c b/main.c
index 58fe58e..41b18dc 100644
--- a/main.c
+++ b/main.c
@@ -9,14 +9,15 @@
 #include <sys/stat.h> /* open(2) */
 #include <fcntl.h>
 #include <errno.h> /* errno(3) */
-#include <arpa/inet.h> /* byteorder(3) */
+#include <arpa/inet.h> /* htons(3) */
 #include <netdb.h> /* getaddrinfo(3) */
 #include <stdlib.h> /* atoi(3) */
 #include <string.h> /* strchr(3) */
 #include <time.h> /* clock_gettime(2) */
 #include <signal.h> /* signal(2) */
-#include <sys/prctl.h> /* prctl(2) */
-#include <sys/wait.h> /* waitpid(2) */
+/* #include <sys/prctl.h> */ /* prctl(2) */
+/* #include <sys/wait.h> */ /* waitpid(2) */
+#include <poll.h> /* poll(2) */
 #include "domain2name.c"
 #include "host.c"
 #define MIN(a,b) ((a) < (b) ? (a) : (b))
@@ -45,7 +46,7 @@
 /* DNS PACKET: HEADER QUESTION ANSWER AUTHORITY ADDITIONAL 	datatracker.ietf.org/doc/html/rfc1035
 DEFINITIONS: (those appear somewhere in the packet, packet does not start with definitions!)
 	LABLEN	 8 bits: first two bits zero, then 6 bits length of label
-	POINTER	 8 bits: first two bits one, then 6 bits as offset from first byte of packet
+	POINTER	16 bits: first two bits one, then 14 bits as offset from first byte of packet
 	STRING	a single byte for defining length (0-256 - all eight bits) and then string of chars
 	DOMAIN	 i.) one or more LABLEN followed by ASCII label (no dots) end with either LABLEN 0
 		or a POINTER that points to some LABLEN somewhere else in the packet		-OR-:
@@ -72,6 +73,7 @@ ANSWER:
 	NAME	DOMAIN
 	TYPE	same as QTYPE
 	CLASS	same description as QCLASS, except class 255 ANY is not allowed here
+	TTL	32 bits: unsigned intager of seconds. for this period the record is valid.
 	RDLEN	16 bits: length of RDATA field - this is a number 0-65536, no two zero bits
 	RDATA	A: 4 bytes IP address		NS: DOMAIN	CNAME: DOMAIN
 		SOA: NAME-ns1 NAME-email 32b-serial 32b-refresh 32b-retry 32b-expire 32b-nxdomainttl
@@ -82,12 +84,12 @@ ANSWER:
 GLOBAL HEADER:	24 bytes
 	MAGIC	32 bits: 0xA1B2C3D4 timestamp is s and micros	0xA1B23C4D timestamp is s and nanos
 	MAJOR	16 bits: version	2 https://tools.ietf.org/id/draft-gharris-opsawg-pcap-00.html
-	MINOR	16 bits: version	4 _/	  /-------------------------------------------------\
-	RESERV1	32 bits: unused and set to 0	 < http://en.wikipedia.org/wiki/Frame_check_sequence|
-	RESERV2 32 bits: unused and set to 0	  \--------------------------------------------\  ^ |
-	SNAPLEN	32 bits: larger or equal to size of largest capture of a single packet		|/ \|
-	FCS	 4 bits: if last bit is 1, first 3 tell nr of bytes of FCS appended to every packet/
-	LINKTYP	28 bits: pkt type //tcpdump.org/linktypes.html	101 IPv4/v6	1 ether		|   |
+	MINOR	16 bits: version	4 	/-----------------------------------------------\
+	RESERV1	32 bits: unused and set to 0	| //en.wikipedia.org/wiki/Frame_check_sequence	|
+	RESERV2 32 bits: unused and set to 0	\--------------------------------------------\	|
+	SNAPLEN	32 bits: larger or equal to size of largest capture of a single packet		|
+	FCS	 4 bits: if last bit is 1, first 3 tell nr of bytes of FCS appended to every packet
+	LINKTYP	28 bits: pkt type //tcpdump.org/linktypes.html	101 IPv4/v6	1 ether
 PACKET HEADER:	16 bytes
 	SECONDS	32 bits: UNIX timestamp
 	SUBSECS 32 bits: nanoseconds elapsed since the second, can also be microseconds - see MAGIC
@@ -220,6 +222,17 @@ struct header {
 	uint16_t arcount		__attribute__((packed));
 	char data[];			/* ignored for char[] */
 } __attribute__((packed));
+struct rr { /* name is omitted, first byte of struct is first byte of type */
+	uint16_t type			__attribute__((packed));
+	uint16_t class			__attribute__((packed));
+	uint32_t ttl			__attribute__((packed));
+	uint16_t len			__attribute__((packed));
+	char data[];			/* ignored for char[] */
+} __attribute__((packed));
+struct question {
+	uint16_t type			__attribute__((packed));
+	uint16_t class			__attribute__((packed));
+} __attribute__((packed));
 int logudp (int o /* fd */, struct sockaddr_in s, struct sockaddr_in d, char * u, size_t l /* d */) {
 	if (o == -1)
 		return -1;
@@ -263,7 +276,7 @@ int logudp (int o /* fd */, struct sockaddr_in s, struct sockaddr_in d, char * u
 	}
 	return LOGUDP_L;
 }
-struct in_addr parse_a (const char * u /* >=512B */, const char * d, int l, int n) {
+struct in_addr parse_a (const char * u, int s /* buffer size of u */, const char * d, int l, int n) {
 	struct in_addr r = {	/* this uses heap and does not fix heap if realloc failed. */
 		.s_addr = 0	/* returns 0.0.0.0 in case of error or if no more results for n. */
 	};
@@ -273,59 +286,59 @@ struct in_addr parse_a (const char * u /* >=512B */, const char * d, int l, int
 	char * ž = alloca(y);
 	if (normalizedomain(ž, d, l) < 0)
 		return r;
-	int š = ntohs(((const struct header *) u)->ancount);
+	const struct header * h = (const struct header *) u;
+	int q = ntohs(h->qdcount);
+	int a = ntohs(h->ancount+h->nscount+h->arcount);
 	char * o = NULL;
 	const char * c = u+sizeof(struct header);
-	while (š--) {					/* there's got to be a cleaner way of	*/
-		int č = name2domain_len(u, c);		/* doing this ... someone please review	*/
-		if (č < 0)				/* all those functions and PLEASE run	*/
-			goto r;				/* this program AS UNPRIVILEDGED AS	*/
-		if (!(o = realloc(o, č)))		/* POSSIBLE!				*/
+	while (q--) {
+		int č = name2domain_len(u, s, c);
+		if (č < 0)
+			goto r;
+		if (!(o = realloc(o, č)))
+			goto r;
+		if (!(c = name2domain(o, u, s, c)))
 			goto r;
-		if (!(c = name2domain(o, u, c)))
+		struct question * ć = (struct question *) (c+1);
+		if ((c += sizeof(*ć)+1) >= u+512)
 			goto r;
-		if (c+11 >= u+512)
+	} /* we skip over any questions */
+	while (a--) {
+		int č = name2domain_len(u, s, c);
+		if (č < 0)
+			goto r;
+		if (!(o = realloc(o, č)))
+			goto r;
+		if (!(c = name2domain(o, u, s, c)))
+			goto r;
+		struct rr * ć = (struct rr *) (c+1);
+		if (c+sizeof(*ć) >= u+512)
+			goto r;
+		if ((c += ntohs(ć->len)+sizeof(*ć)+1) >= u+512)
 			goto r;
 		if (y != č)
-			goto c;
+			continue;
 		if (memcmp(o, ž, y))
-			goto c;
-		if (ntohs(*(uint16_t *) c+1) != A)
-			goto c;
-		if (ntohs(*(uint16_t *) c+3) != In)
-			goto c;
-		if (ntohs(*(uint16_t *) c+5) != 4)	/* this is actually a malformed packet, */
-			goto c;				/* A resource record must be four bytes */
+			continue;
+		if (ntohs(ć->type) != A)
+			continue;
+		if (ntohs(ć->class) != In)
+			continue;
+		if (ntohs(ć->len) != 4)			/* this is actually a malformed packet, */
+			continue;			/* A resource record must be four bytes */
 		if (n--)
-			goto c;
-		r.s_addr = *(in_addr_t *) c+7;
+			continue;
+		r.s_addr = *(in_addr_t *) (ć->data);
 		goto r;
-c:
-		c += ntohs(*(uint16_t *) c+5)+7;
-		if (c >= u+512)
-			goto r;
-		continue;
-	}
+	} /* we scroll over answers now and treat all three types the same, waiting for our A */
 r:
 	free(o);
 	return r;
 } /* returns nth IP of A record for domain d of length l in response packet u or 0.0.0.0 for err */
 int finish = 0;
-int c = -1; /* child process */
 void handler () {
-	if (++finish >= 3) {
-		if (c != -1)
-			kill(c, SIGHUP);
+	if (++finish >= 3)
 		exit(1);
-	}
-}
-struct timespec lp = { /* last packet */
-	.tv_sec = 0
-};
-void child_handler () {
-	if (clock_gettime(CLOCK_MONOTONIC, &lp) == -1)
-		perror("clock_gettime(CLOCK_MONOTONIC, &lp)");
-	fprintf(stderr, "recv child received signal\n");
 }
 int main (int argc, char ** argv) {
 	int r = 2;
@@ -369,7 +382,7 @@ int main (int argc, char ** argv) {
 			case 'o':
 				if ((o = open(optarg, O_CREAT | O_TRUNC | O_WRONLY, 00664)) == -1) {
 					perror("open(optarg, O_CREAT | O_TRUNC | O_WRONLY)");
-					r = 3;
+					r = 1;
 					goto r;
 				}
 				struct pcap_global g = {
@@ -383,7 +396,7 @@ int main (int argc, char ** argv) {
 				};
 				if (write(o, &g, sizeof g) == -1) {
 					perror("write(o, &g, sizeof g)");
-					r = 4;
+					r = 2;
 					goto r;
 				}
 				break;
@@ -399,7 +412,7 @@ int main (int argc, char ** argv) {
 			case -1:
 				if (!(l = argc-optind)) {
 					fprintf(stderr, "specify targets to scan :: " HELP, argv[0]);
-					r = 5;
+					r = 3;
 					goto r;
 				}
 				n = alloca(l*sizeof *n);
@@ -410,14 +423,14 @@ int main (int argc, char ** argv) {
 				goto o;
 			case '?':
 				fprintf(stderr, "unknown option :: " HELP, argv[0]);
-				r = 6;
+				r = 4;
 				goto r;
 			case ':':
 				fprintf(stderr, "missing option argument :: " HELP, argv[0]);
-				r = 7;
+				r = 5;
 				goto r;
 			default:
-				r = 8;
+				r = 6;
 				goto r;
 		}
 	}
@@ -427,88 +440,34 @@ o:
 		fprintf(stderr, "resolving %s ... ", d);
 		if ((e = resolve(d, &a.s_addr))) {
 			fprintf(stderr, "failed: %s\n", gai_strerror(e));
-			r = 9;
+			r = 7;
 			goto r;
 		}
 		fprintf(stderr, " %s\n", inet_ntoa(a));
 	}
 	if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
 		perror("socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)");
-		r = 10;
+		r = 8;
 		goto r;
 	}
 	if (bind(s, (struct sockaddr *) &b, sizeof(struct sockaddr))) {
 		perror("bind(s, (struct sokaddr *) &b, sizeof(struct sockaddr))");
-		r = 11;
-		goto r;
-	}
-	if ((c = fork()) == -1) {
-		perror("fork()");
-		r = 12;
+		r = 9;
 		goto r;
 	}
-	if (!c) {
-		signal(SIGINT, child_handler);
-		signal(SIGTERM, child_handler);
-		while (1) {
-			char u[512]; /* max dns packet */
-			struct sockaddr_in f;
-			socklen_t č = sizeof f;
-			int š;
-			if ((š = recvfrom(s, u, 512, lp.tv_sec ? MSG_DONTWAIT : 0,
-						(struct sockaddr *) &f, &č)) == -1) {
-				if (errno != EWOULDBLOCK) {
-					perror("recvfrom(s, u, 512, lp.tv_sec ? MSG_DONTWAIT : 0...");
-					return 1;
-				}
-				struct timespec z;
-				if (clock_gettime(CLOCK_MONOTONIC, &z) == -1) {
-					perror("clock_gettime(CLOCK_MONOTONIC, &z)");
-					return 2;
-				}
-				if ((z.tv_sec*1000000 + z.tv_nsec/1000)
-						- (lp.tv_sec*1000000 + lp.tv_nsec/1000) > w) {
-					fprintf(stderr, "no more packets are received. timeout.\n");
-					return 0;
-				}
-				continue;
-			}
-			if (lp.tv_sec)
-				if (clock_gettime(CLOCK_MONOTONIC, &lp) == -1) {
-					perror("clock_gettime(CLOCK_MONOTONIC, &lp)");
-					return 2;
-				}
-			int ž;
-			if ((ž = logudp(o, f, b, u, š)) < -1) {
-				fprintf(stderr, "logudp(o, f, b, u, š) == %d\n", ž);
-				return 3;
-			}
-			fprintf(stderr, "received response from %s\n", inet_ntoa(f.sin_addr));
-		} /* TODO: parse the response with parse_a etc above this line (: */
-		return 0;
-	}
+	struct timespec lp = { /* last packet */
+		.tv_sec = 0
+	};
 	while (!finish) {
 		if (!(h = host(n[i], ++j)).s_addr) {
 			if (++i >= l) {
-				int s;
 				fprintf(stderr, "finished sending, waiting for last replies\n");
-				if (kill(c, SIGINT) == -1) { /* child waits */
-					perror("kill(c, SIGINT)");
-					r = 13;
-					goto r;
-				}
-				c = -1;
-				if (wait(&s) == -1) {
-					perror("wait(&s)");
-					r = 14;
-					goto r;
-				}
-				if (WIFEXITED(s) && !WEXITSTATUS(s)) {
-					r = 0;
+				if (clock_gettime(CLOCK_MONOTONIC, &lp) == -1) {
+					perror("clock_gettime(CLOCK_MONOTONIC, &z)");
+					r = 10;
 					goto r;
 				}
-				r = 15;
-				goto r;
+				goto i;
 			}
 			else
 				h = host(n[i], (j = 0));
@@ -527,12 +486,16 @@ o:
 			.arcount = 0
 		};
 		int v = domain2name_len(d, strlen(d));
+#define L (sizeof h + v + 2*2)
 		if (v < 0) {
-			r = 16;
+			r = 11;
 			goto r;
 		}
-#define L (sizeof h + v + 2*2)
-		char * u = alloca(L);
+		if (L > 65535) { /* pebkac, there'll be no error message here */
+			r = 12;
+			goto r;
+		}
+		char u[65535]; /* max udp packet, alloca in a loop would be bad (not scope based) */
 		char * c;
 		uint16_t y = htons(A);
 		uint16_t k = htons(In);
@@ -543,43 +506,96 @@ o:
 		int ž;
 		if ((ž = logudp(o, b, e, u, L)) < -1) {
 			fprintf(stderr, "logudp(o, b, e, u, L) == %d\n", ž);
-			r = 17;
+			r = 13;
 			goto r;
 		}
 		if (sendto(s, u, L, 0, (struct sockaddr *) &e, sizeof(struct sockaddr)) == -1) {
 			perror("sendto(s, u, L, 0, (struct sockaddr *) &e, sizeof(struct sockaddr))");
-			r = 18;
+			r = 14;
 			goto r;
 		}
-		if (usleep(t)) {
-			perror("usleep(t)");
-			r = 19;
+		struct timespec z;
+i:
+		if (clock_gettime(CLOCK_MONOTONIC, &z) == -1) {
+			perror("clock_gettime(CLOCK_MONOTONIC, &z)");
+			r = 15;
 			goto r;
 		}
-	}
-	if (finish)
-		kill(c, SIGTERM); /* stop receiving */
-r:
-	if (!r && j != -1) {
-		char * x = alloca(l*31+strlen("SCANNED  \n0"));
-		strcpy(x, "SCANNED ");
-		for (int m = 0; m < (finish ? i : l); m++) {
-			strcat(x, inet_ntoa(n[m].addr));
-			strcat(x, "/");
-			strcat(x, inet_ntoa(n[m].mask));
-			strcat(x, " ");
+		if ((z.tv_sec*1000000 + z.tv_nsec/1000) - (lp.tv_sec*1000000 + lp.tv_nsec/1000) > w
+				&& lp.tv_sec) {
+			fprintf(stderr, "no more packets were received for -w microseconds. done.\n");
+			r = 0;
+			goto r;
+		}
+		struct pollfd q = {
+			.fd = s,
+			.events = POLLIN
+		};
+		int p;
+		if ((p = poll(&q, 1, t/1000 == 0 ? 1 : t/1000)) == -1) {
+			perror("poll(&q, 1, t/1000 == 0 ? 1 : t/1000)");
+			r = 16;
+			goto r;
 		}
-		strcat(x, "\n");
-		write(STDIN_FILENO, x, strlen(x)); /* vsi tele strlen in strcat niso najboljša pot */
+		if (!p) {
+			if (lp.tv_sec)
+				goto i;
+			else
+				continue;
+		}
+		if (q.revents & POLLERR || q.revents & POLLHUP || q.revents & POLLNVAL) {
+			r = 17;
+			goto r;
+		}
+		struct sockaddr_in f;
+		socklen_t č = sizeof f;
+		while (1) {
+			int š;
+			if ((š = recvfrom(s, u, 65535, MSG_DONTWAIT, (struct sockaddr *) &f, &č))
+				       == -1) {
+				if (errno != EWOULDBLOCK) {
+					perror("recvfrom(s, u, 65535, MSG_DONTWAIT, (struct sock...");
+					r = 18;
+					goto r;
+				}
+				break;
+			}
+			if (lp.tv_sec)
+				lp = z; /* this loop ends nearly in an instant */
+			if ((ž = logudp(o, f, b, u, š)) < -1) {
+				fprintf(stderr, "logudp(o, f, b, u, š) == %d\n", ž);
+				return 3;
+			}
+			fprintf(stderr, "received response from %s\n", inet_ntoa(f.sin_addr));
+			ž = 0;
+			struct in_addr i = parse_a(u, 65535, d, strlen(d), ž++);
+			if (i.s_addr == a.s_addr) /* if we go back to multithread, change to write. */
+				printf("WORKING %s\n", inet_ntoa(f.sin_addr));
+			if (i.s_addr && i.s_addr != a.s_addr)
+				printf("LYING %s WITH %s\n", inet_ntoa(f.sin_addr), inet_ntoa(i));
+
+		}
+		if (z.tv_sec)
+			goto i;
 	}
+r:
+	if (!r && j != -1) { /* TODO: tell EXACT packets that were sent before termination. */
+		char * x = alloca(l*31+strlen("SCANNED  \n0"));	/* currently, if scan was */
+		strcpy(x, "SCANNED ");				/* terminated, only networks before */
+		for (int m = 0; m < (finish ? i : l); m++) {	/* network at which scan was */
+			strcat(x, inet_ntoa(n[m].addr));	/* terminated are reported to be */
+			strcat(x, "/");				/* scanned, not mentioning the */
+			strcat(x, inet_ntoa(n[m].mask));	/* part of the last not mentioned */
+			strcat(x, " ");				/* network that was scanned. */
+		}						/* this may lead to statistical */
+		strcat(x, "\n");				/* issues because it would appear */
+		write(STDIN_FILENO, x, strlen(x));		/* as if we received packets from */
+	}							/* hosts we haven't queried yet. */
 	if (s != -1)
 		if (close(s))
 			perror("close(s)");
 	if (o != -1)
 		if (close(o))
 			perror("close(o)");
-	if (c != -1)
-		if (kill(c, SIGKILL) == -1)
-			perror("kill(c, SIGKILL)");
 	return r;
 }