diff --git a/.ci_scripts/install_packages.sh b/.ci_scripts/install_packages.sh
index a7b016c806e62a7b608fe356c795bbafb80ec2ae..18e55e3e3245dcf10221727a137d67d0ed9b8b84 100755
--- a/.ci_scripts/install_packages.sh
+++ b/.ci_scripts/install_packages.sh
@@ -1,4 +1,4 @@
#!/bin/bash
-apt update
-apt install -y gcc make cmake libcunit1 libcunit1-dev net-tools valgrind cppcheck
+apt-get update
+DEBIAN_FRONTEND=noninteractive apt-get install -y gcc make cmake libcunit1 libcunit1-dev net-tools valgrind cppcheck
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 73dbda5c19bcf5ca45f42976791e6c6688cc90a4..1fe705ee63da0590b55f28e30d6f29cf4c9b2d25 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -31,4 +31,6 @@ set(PARSERS header dns dhcp http igmp ssdp coap)
# Subdirectories containing code
add_subdirectory(src)
-add_subdirectory(test)
+IF( NOT OPENWRT_CROSSCOMPILING )
+ add_subdirectory(test)
+ENDIF()
diff --git a/include/dns.h b/include/dns.h
index 7b6975ea1b8835199ff93868ab879542929b9efd..d28d8dcf1df3551fdbc47f5c7481111a35a18a2d 100644
--- a/include/dns.h
+++ b/include/dns.h
@@ -1,5 +1,6 @@
/**
- * @file include/dns.h
+ * @file include/parsers/dns.h
+ * @author François De Keersmaeker (francois.dekeersmaeker@uclouvain.be)
* @brief DNS message parser
* @date 2022-09-09
*
@@ -15,6 +16,11 @@
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
#include <arpa/inet.h>
#include "packet_utils.h"
#include "dns_map.h"
@@ -71,7 +77,7 @@ typedef struct dns_header {
*/
typedef struct dns_question {
char *qname;
- dns_rr_type_t qtype;
+ uint16_t qtype;
uint16_t qclass;
} dns_question_t;
@@ -89,7 +95,7 @@ typedef union {
*/
typedef struct dns_resource_record {
char *name;
- dns_rr_type_t rtype;
+ uint16_t rtype;
uint16_t rclass;
uint32_t ttl;
uint16_t rdlength;
@@ -187,10 +193,10 @@ dns_question_t* dns_get_question(dns_question_t *questions, uint16_t qdcount, ch
/**
* @brief Retrieve the IP addresses corresponding to a given domain name in a DNS Answers list.
- *
+ *
* Searches a DNS Answer list for a specific domain name and returns the corresponding IP address.
* Processes each Answer recursively if the Answer Type is a CNAME.
- *
+ *
* @param answers DNS Answers list to search in
* @param ancount number of Answers in the list
* @param domain_name domain name to search for
@@ -199,6 +205,37 @@ dns_question_t* dns_get_question(dns_question_t *questions, uint16_t qdcount, ch
ip_list_t dns_get_ip_from_name(dns_resource_record_t *answers, uint16_t ancount, char *domain_name);
+///// COMMUNICATE /////
+
+/**
+ * @brief Convert domain name to message format.
+ *
+ * @param dst converted domain name
+ * @param src domain name to convert
+ */
+void dns_convert_qname(char *dst, char *src, uint16_t len);
+
+/**
+ * @brief Send a DNS query for the given domain name.
+ *
+ * @param qname domain name to query for
+ * @param sockfd socket file descriptor
+ * @param server_addr DNS server IPv4 address
+ * @return 0 if the query was sent successfully, -1 otherwise
+ */
+int dns_send_query(char *qname, int sockfd, struct sockaddr_in *server_addr);
+
+/**
+ * @brief Receive a DNS response.
+ *
+ * @param sockfd socket file descriptor
+ * @param server_addr DNS server IPv4 address
+ * @param dns_message allocated buffer which will be filled with the DNS response message, upon success
+ * @return 0 if DNS response was received successfully, -1 otherwise
+ */
+int dns_receive_response(int sockfd, struct sockaddr_in *server_addr, dns_message_t *dns_message);
+
+
///// DESTROY /////
/**
diff --git a/src/dns.c b/src/dns.c
index 5c3126517eaa2b5b23cf42f513f2fa13a07390cd..3b7c305047bcf4393161ad0e9beec17299dcd1d1 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -1,5 +1,6 @@
/**
- * @file src/dns.c
+ * @file src/parsers/dns.c
+ * @author François De Keersmaeker (francois.dekeersmaeker@uclouvain.be)
* @brief DNS message parser
* @date 2022-09-09
*
@@ -9,6 +10,13 @@
#include "dns.h"
+// DNS message timeout
+#define TIMEOUT 5 // Timeout value, in seconds
+struct timeval timeout = {
+ .tv_sec = TIMEOUT,
+ .tv_usec = 0
+};
+
///// PARSING /////
@@ -191,7 +199,7 @@ dns_resource_record_t* dns_parse_rrs(uint16_t count, uint8_t *data, uint16_t *of
// Parse domain name
(rrs + i)->name = dns_parse_domain_name(data, offset);
// Parse rtype, rclass and TTL
- dns_rr_type_t rtype = ntohs(*((uint16_t *) (data + *offset)));
+ uint16_t rtype = ntohs(*((uint16_t *) (data + *offset)));
(rrs + i)->rtype = rtype;
(rrs + i)->rclass = ntohs(*((uint16_t *) (data + *offset + 2))) & DNS_CLASS_MASK;
(rrs + i)->ttl = ntohl(*((uint32_t *) (data + *offset + 4)));
@@ -199,7 +207,7 @@ dns_resource_record_t* dns_parse_rrs(uint16_t count, uint8_t *data, uint16_t *of
uint16_t rdlength = ntohs(*((uint16_t *) (data + *offset + 8)));
(rrs + i)->rdlength = rdlength;
*offset += 10;
- (rrs + i)->rdata = dns_parse_rdata(rtype, rdlength, data, offset);
+ (rrs + i)->rdata = dns_parse_rdata((dns_rr_type_t) rtype, rdlength, data, offset);
}
return rrs;
}
@@ -326,39 +334,48 @@ dns_question_t* dns_get_question(dns_question_t *questions, uint16_t qdcount, ch
/**
* @brief Retrieve the IP addresses corresponding to a given domain name in a DNS Answers list.
- *
+ *
* Searches a DNS Answer list for a specific domain name and returns the corresponding IP address.
* Processes each Answer recursively if the Answer Type is a CNAME.
- *
+ *
* @param answers DNS Answers list to search in
* @param ancount number of Answers in the list
* @param domain_name domain name to search for
* @return struct ip_list representing the list of corresponding IP addresses
*/
-ip_list_t dns_get_ip_from_name(dns_resource_record_t *answers, uint16_t ancount, char *domain_name) {
+ip_list_t dns_get_ip_from_name(dns_resource_record_t *answers, uint16_t ancount, char *domain_name)
+{
ip_list_t ip_list;
ip_list.ip_count = 0;
ip_list.ip_addresses = NULL;
char *cname = domain_name;
- for (uint16_t i = 0; i < ancount; i++) {
- if (strcmp((answers + i)->name, cname) == 0) {
+ for (uint16_t i = 0; i < ancount; i++)
+ {
+ if (strcmp((answers + i)->name, cname) == 0)
+ {
dns_rr_type_t rtype = (answers + i)->rtype;
if (rtype == A || rtype == AAAA)
{
// Handle IP list length
- if (ip_list.ip_addresses == NULL) {
- ip_list.ip_addresses = (ip_addr_t *) malloc(sizeof(ip_addr_t));
- } else {
+ if (ip_list.ip_addresses == NULL)
+ {
+ ip_list.ip_addresses = (ip_addr_t *)malloc(sizeof(ip_addr_t));
+ }
+ else
+ {
void *realloc_ptr = realloc(ip_list.ip_addresses, (ip_list.ip_count + 1) * sizeof(ip_addr_t));
- if (realloc_ptr == NULL) {
+ if (realloc_ptr == NULL)
+ {
// Handle realloc error
free(ip_list.ip_addresses);
fprintf(stderr, "Error reallocating memory for IP list.\n");
ip_list.ip_count = 0;
ip_list.ip_addresses = NULL;
return ip_list;
- } else {
- ip_list.ip_addresses = (ip_addr_t*) realloc_ptr;
+ }
+ else
+ {
+ ip_list.ip_addresses = (ip_addr_t *)realloc_ptr;
}
}
// Handle IP version and value
@@ -375,6 +392,152 @@ ip_list_t dns_get_ip_from_name(dns_resource_record_t *answers, uint16_t ancount,
}
+///// COMMUNICATE /////
+
+/**
+ * @brief Convert domain name to message format.
+ *
+ * @param dst converted domain name
+ * @param src domain name to convert
+ */
+void dns_convert_qname(char *dst, char *src, uint16_t len) {
+ int lock = 0; // Points to the next index to fill in the output array
+
+ // Start by iterating over each character in the input domain name
+ for (int i = 0; i < len; i++)
+ {
+ int segment_len = 0; // Length of the current segment
+
+ // Count the length of the current segment until we hit a dot or the end of the string
+ while (*(src + i) != '.' && *(src + i) != '\0')
+ {
+ *(dst + lock + 1 + segment_len) = *(src + i);
+ segment_len++;
+ i++;
+ }
+
+ *(dst + lock) = segment_len; // Prefix the segment with its length
+ lock += segment_len + 1; // Move the index past the current segment
+ }
+
+ *(dst + lock) = '\0'; // Null terminate the DNS label format string
+}
+
+/**
+ * @brief Send a DNS query for the given domain name.
+ *
+ * @param qname domain name to query for
+ * @param sockfd socket file descriptor
+ * @param server_addr DNS server IPv4 address
+ */
+int dns_send_query(char *qname, int sockfd, struct sockaddr_in *server_addr) {
+ // Buffer that will contain the message
+ uint16_t qname_len = strlen(qname);
+ uint16_t qname_labels_len = qname_len + sizeof(uint8_t) * 2;
+ uint16_t dns_questions_size = qname_labels_len + sizeof(uint16_t) * 2;
+ uint16_t dns_message_size = DNS_HEADER_SIZE + dns_questions_size;
+ uint8_t *buffer = (uint8_t *) malloc(dns_message_size);
+
+ // Populate DNS Header fields
+ dns_header_t dns_header;
+ dns_header.id = htons((uint16_t) getpid());
+ dns_header.flags = htons((uint16_t) (0b0000000100000000));
+ dns_header.qr = 0; // Query: qr = 0
+ dns_header.qdcount = htons((uint16_t) 1); // Only 1 question
+ dns_header.ancount = 0;
+ dns_header.nscount = 0;
+ dns_header.arcount = 0;
+
+ // Populate DNS Question fields
+ dns_question_t dns_question;
+ dns_question.qname = (char *)malloc(qname_labels_len);
+ dns_convert_qname(dns_question.qname, qname, qname_len);
+ dns_question.qtype = htons((uint16_t) A);
+ dns_question.qclass = htons((uint16_t) 1);
+
+ // Copy all DNS fields
+ memcpy(buffer, &dns_header, sizeof(uint16_t) * 2);
+ memcpy(buffer + sizeof(uint16_t) * 2, &(dns_header.qdcount), sizeof(uint16_t) * 4);
+ memcpy(buffer + DNS_HEADER_SIZE, dns_question.qname, qname_labels_len);
+ memcpy(buffer + DNS_HEADER_SIZE + qname_labels_len, &(dns_question.qtype), sizeof(uint16_t) * 2);
+
+ // Set socket timeout
+ if (setsockopt(sockfd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout)) < 0)
+ {
+ perror("Error setting socket send timeout");
+ // Free memory
+ free(dns_question.qname);
+ free(buffer);
+ return -1;
+ }
+
+ // Send DNS message
+ #ifdef DEBUG
+ printf("Sending DNS query for domain name %s to server %s\n", qname, inet_ntoa(server_addr->sin_addr));
+ #endif /* DEBUG */
+ if (sendto(sockfd, buffer, dns_message_size, 0, (struct sockaddr *)server_addr, sizeof(*server_addr)) < 0)
+ {
+ if (errno == EWOULDBLOCK || errno == EAGAIN)
+ {
+ printf("DNS query for %s timed out.\n", qname);
+ } else {
+ perror("Failed sending DNS query.");
+ }
+ // Free memory
+ free(dns_question.qname);
+ free(buffer);
+ return -1;
+ }
+
+ // DNS query was sent successfully
+ free(dns_question.qname);
+ free(buffer);
+ return 0;
+}
+
+/**
+ * @brief Receive a DNS response.
+ *
+ * @param sockfd socket file descriptor
+ * @param server_addr DNS server IPv4 address
+ * @param dns_message allocated buffer which will be filled with the DNS response message, upon success
+ * @return 0 if DNS response was received successfully, -1 otherwise
+ */
+int dns_receive_response(int sockfd, struct sockaddr_in *server_addr, dns_message_t* dns_message)
+{
+ // Receiving buffer
+ int bufsize = 65536;
+ uint8_t *buffer = (uint8_t *)malloc(bufsize);
+
+ // Set socket timeout
+ if (setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)) < 0)
+ {
+ perror("Error setting socket receive timeout");
+ free(buffer);
+ return -1;
+ }
+
+ // Await response
+ int n = recvfrom(sockfd, (char *)buffer, bufsize, 0, NULL, NULL);
+ if (n < 0)
+ {
+ if (errno == EWOULDBLOCK || errno == EAGAIN)
+ {
+ printf("DNS receive timed out\n");
+ } else {
+ perror("Failed receiving DNS response.");
+ }
+ free(buffer);
+ return -1;
+ }
+
+ // DNS response was received successfully, parse it
+ *dns_message = dns_parse_message(buffer);
+
+ free(buffer);
+ return 0;
+}
+
///// DESTROY /////
/**
@@ -410,7 +573,7 @@ static void dns_free_rrs(dns_resource_record_t *rrs, uint16_t count) {
dns_resource_record_t rr = *(rrs + i);
if (rr.rdlength > 0) {
free(rr.name);
- dns_free_rdata(rr.rdata, rr.rtype);
+ dns_free_rdata(rr.rdata, (dns_rr_type_t) rr.rtype);
}
}
free(rrs);
@@ -539,7 +702,7 @@ void dns_print_rr(char* section_name, dns_resource_record_t rr) {
printf(" Class: %hd\n", rr.rclass);
printf(" TTL [s]: %d\n", rr.ttl);
printf(" Data length: %hd\n", rr.rdlength);
- printf(" RDATA: %s\n", dns_rdata_to_str(rr.rtype, rr.rdlength, rr.rdata));
+ printf(" RDATA: %s\n", dns_rdata_to_str((dns_rr_type_t) rr.rtype, rr.rdlength, rr.rdata));
}
/**
diff --git a/test/dns.c b/test/dns.c
index 80a311155f603c0392d3b612bccd3cb117651ef3..03373a2674a0e6cd0b3b7f3d7266a1f6f31ee8ab 100644
--- a/test/dns.c
+++ b/test/dns.c
@@ -1,5 +1,6 @@
/**
- * @file test/dns.c
+ * @file test/parsers/dns.c
+ * @author François De Keersmaeker (francois.dekeersmaeker@uclouvain.be)
* @brief Unit tests for the DNS parser
* @date 2022-09-09
*
@@ -63,6 +64,27 @@ void compare_rrs(uint16_t count, dns_resource_record_t *actual, dns_resource_rec
}
}
+/**
+ * @brief Unit test for the dns_convert_qname function.
+ */
+void test_dns_convert_qname() {
+ // Test parameters
+ char *qname = "www.google.com";
+ uint8_t qname_len = strlen(qname);
+ char *expected = "\3www\6google\3com";
+ uint8_t converted_len = qname_len + 2;
+
+ // Execute function
+ char *actual = (char*) malloc(converted_len);
+ dns_convert_qname(actual, qname, qname_len);
+
+ // Verify result
+ CU_ASSERT_STRING_EQUAL(actual, expected);
+
+ // Clean up
+ free(actual);
+}
+
/**
* Unit test for the DNS parser.
*/
@@ -130,16 +152,16 @@ void test_dns_xiaomi() {
CU_ASSERT_TRUE(dns_contains_full_domain_name(message.questions, message.header.qdcount, domain_name));
char *suffix = "api.io.mi.com";
CU_ASSERT_TRUE(dns_contains_suffix_domain_name(message.questions, message.header.qdcount, suffix, strlen(suffix)));
- domain_name = "www.example.org";
+ domain_name = "swag.framinem.org";
CU_ASSERT_FALSE(dns_contains_full_domain_name(message.questions, message.header.qdcount, domain_name));
- suffix = "example.org";
+ suffix = "framinem.com";
CU_ASSERT_FALSE(dns_contains_suffix_domain_name(message.questions, message.header.qdcount, suffix, strlen(suffix)));
// Get question from domain name
domain_name = "business.smartcamera.api.io.mi.com";
dns_question_t *question_lookup = dns_get_question(message.questions, message.header.qdcount, domain_name);
CU_ASSERT_PTR_NOT_NULL(question_lookup);
- domain_name = "www.example.org";
+ domain_name = "swag.framinem.org";
question_lookup = dns_get_question(message.questions, message.header.qdcount, domain_name);
CU_ASSERT_PTR_NULL(question_lookup);
@@ -150,7 +172,7 @@ void test_dns_xiaomi() {
CU_ASSERT_EQUAL(ip_list.ip_count, 1);
CU_ASSERT_STRING_EQUAL(ipv4_net_to_str(ip_list.ip_addresses->value.ipv4), ip_address);
free(ip_list.ip_addresses);
- domain_name = "www.example.org";
+ domain_name = "swag.framinem.org";
ip_list = dns_get_ip_from_name(message.answers, message.header.ancount, domain_name);
CU_ASSERT_EQUAL(ip_list.ip_count, 0);
CU_ASSERT_PTR_NULL(ip_list.ip_addresses);
@@ -278,16 +300,16 @@ void test_dns_office() {
CU_ASSERT_TRUE(dns_contains_full_domain_name(message.questions, message.header.qdcount, domain_name));
char* suffix = "office.com";
CU_ASSERT_TRUE(dns_contains_suffix_domain_name(message.questions, message.header.qdcount, suffix, strlen(suffix)));
- domain_name = "www.example.org";
+ domain_name = "swag.framinem.org";
CU_ASSERT_FALSE(dns_contains_full_domain_name(message.questions, message.header.qdcount, domain_name));
- suffix = "example.org";
+ suffix = "framinem.org";
CU_ASSERT_FALSE(dns_contains_suffix_domain_name(message.questions, message.header.qdcount, suffix, strlen(suffix)));
// Get question from domain name
domain_name = "outlook.office.com";
dns_question_t *question_lookup = dns_get_question(message.questions, message.header.qdcount, domain_name);
CU_ASSERT_PTR_NOT_NULL(question_lookup);
- domain_name = "www.example.org";
+ domain_name = "swag.framinem.org";
question_lookup = dns_get_question(message.questions, message.header.qdcount, domain_name);
CU_ASSERT_PTR_NULL(question_lookup);
@@ -305,7 +327,7 @@ void test_dns_office() {
CU_ASSERT_STRING_EQUAL(ipv4_net_to_str((ip_list.ip_addresses + i)->value.ipv4), ip_addresses[i]);
}
free(ip_list.ip_addresses);
- domain_name = "www.example.org";
+ domain_name = "swag.framinem.org";
ip_list = dns_get_ip_from_name(message.answers, message.header.ancount, domain_name);
CU_ASSERT_EQUAL(ip_list.ip_count, 0);
CU_ASSERT_PTR_NULL(ip_list.ip_addresses);
@@ -314,6 +336,39 @@ void test_dns_office() {
dns_free_message(message);
}
+/**
+ * @brief Test the `dns_send_query` and `dns_receive_response` functions.
+ */
+void test_dns_send_receive() {
+ // Initialize
+ int ret;
+ char *domain_name = "www.google.com";
+
+ // Open socket
+ int sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+ CU_ASSERT_TRUE(sockfd > 0);
+
+ // Server address: network gateway
+ struct sockaddr_in server_addr;
+ memset(&server_addr, 0, sizeof(server_addr));
+ server_addr.sin_family = AF_INET;
+ server_addr.sin_port = htons(53);
+ server_addr.sin_addr.s_addr = inet_addr("8.8.8.8");
+
+ // Send query for dummy domain name
+ ret = dns_send_query(domain_name, sockfd, &server_addr);
+ CU_ASSERT_EQUAL(ret, 0);
+
+ // Receive response
+ dns_message_t dns_response;
+ ret = dns_receive_response(sockfd, &server_addr, &dns_response);
+ CU_ASSERT_EQUAL(ret ,0);
+ CU_ASSERT_STRING_EQUAL(dns_response.questions->qname, domain_name);
+
+ // Free memory
+ dns_free_message(dns_response);
+}
+
/**
* Main function for the unit tests.
*/
@@ -325,8 +380,10 @@ int main(int argc, char const *argv[])
printf("Test suite: dns\n");
CU_pSuite suite = CU_add_suite("dns", NULL, NULL);
// Run tests
+ CU_add_test(suite, "dns-convert-qname", test_dns_convert_qname);
CU_add_test(suite, "dns-xiaomi", test_dns_xiaomi);
CU_add_test(suite, "dns-office", test_dns_office);
+ CU_add_test(suite, "dns-send-receive", test_dns_send_receive);
CU_basic_run_tests();
CU_cleanup_registry();
return 0;