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use bool type and do some minor changes
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@mwarning
mwarning committed Nov 8, 2023
1 parent 2a47791 commit 81cc8c5
Showing 1 changed file with 51 additions and 45 deletions.
96 changes: 51 additions & 45 deletions main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -8,9 +8,10 @@
#include <malloc.h>
#include <errno.h>
#include <string.h>
#include <stdbool.h>
#include <stdint.h>

#define BUF_SIZE 1500
#define BUFFER_SIZE 1500
#define MIN(x, y) ((x) <= (y) ? (x) : (y))


Expand Down Expand Up @@ -154,20 +155,20 @@ struct Message {
struct ResourceRecord *additionals;
};

int get_A_Record(uint8_t addr[4], const char domain_name[])
bool get_A_Record(uint8_t addr[4], const char domain_name[])
{
if (strcmp("foo.bar.com", domain_name) == 0) {
addr[0] = 192;
addr[1] = 168;
addr[2] = 1;
addr[3] = 1;
return 0;
return true;
} else {
return -1;
return false;
}
}

int get_AAAA_Record(uint8_t addr[16], const char domain_name[])
bool get_AAAA_Record(uint8_t addr[16], const char domain_name[])
{
if (strcmp("foo.bar.com", domain_name) == 0) {
addr[0] = 0xfe;
Expand All @@ -186,9 +187,9 @@ int get_AAAA_Record(uint8_t addr[16], const char domain_name[])
addr[13] = 0x00;
addr[14] = 0x00;
addr[15] = 0x01;
return 0;
return true;
} else {
return -1;
return false;
}
}

Expand All @@ -210,7 +211,7 @@ void print_hex(uint8_t *buf, size_t len)
{
int i;
printf("%zu bytes:\n", len);
for (i = 0; i < len; ++i)
for (i = 0; i < len; i += 1)
printf("%02x ", buf[i]);
printf("\n");
}
Expand All @@ -232,15 +233,15 @@ void print_resource_record(struct ResourceRecord *rr)
case A_Resource_RecordType:
printf("Address Resource Record { address ");

for (i = 0; i < 4; ++i)
for (i = 0; i < 4; i += 1)
printf("%s%u", (i ? "." : ""), rd->a_record.addr[i]);

printf(" }");
break;
case AAAA_Resource_RecordType:
printf("AAAA Resource Record { address ");

for (i = 0; i < 16; ++i)
for (i = 0; i < 16; i += 1)
printf("%s%02x", (i ? ":" : ""), rd->aaaa_record.addr[i]);

printf(" }");
Expand Down Expand Up @@ -415,20 +416,20 @@ void encode_header(struct Message *msg, uint8_t **buffer)
put16bits(buffer, msg->arCount);
}

int decode_msg(struct Message *msg, const uint8_t *buffer, int size)
bool decode_msg(struct Message *msg, const uint8_t *buffer, size_t size)
{
int i;

decode_header(msg, &buffer);

if (msg->anCount != 0 || msg->nsCount != 0) {
printf("Only questions expected!\n");
return -1;
return false;
}

// parse questions
uint32_t qcount = msg->qdCount;
for (i = 0; i < qcount; ++i) {
for (i = 0; i < qcount; i += 1) {
struct Question *q = malloc(sizeof(struct Question));

q->qName = decode_domain_name(&buffer, size);
Expand All @@ -437,7 +438,7 @@ int decode_msg(struct Message *msg, const uint8_t *buffer, int size)

if (q->qName == NULL) {
printf("Failed to decode domain name!\n");
return -1;
return false;
}

// prepend question to questions list
Expand All @@ -447,7 +448,7 @@ int decode_msg(struct Message *msg, const uint8_t *buffer, int size)

// We do not expect any resource records to parse here.

return 0;
return true;
}

// For every question in the message add a appropiate resource record
Expand All @@ -457,7 +458,6 @@ void resolve_query(struct Message *msg)
struct ResourceRecord *beg;
struct ResourceRecord *rr;
struct Question *q;
int rc;

// leave most values intact for response
msg->qr = 1; // this is a response
Expand Down Expand Up @@ -490,27 +490,22 @@ void resolve_query(struct Message *msg)
switch (q->qType) {
case A_Resource_RecordType:
rr->rd_length = 4;
rc = get_A_Record(rr->rd_data.a_record.addr, q->qName);
if (rc < 0)
{
if (!get_A_Record(rr->rd_data.a_record.addr, q->qName)) {
free(rr->name);
free(rr);
goto next;
}
break;
case AAAA_Resource_RecordType:
rr->rd_length = 16;
rc = get_AAAA_Record(rr->rd_data.aaaa_record.addr, q->qName);
if (rc < 0)
{
if (!get_AAAA_Record(rr->rd_data.aaaa_record.addr, q->qName)) {
free(rr->name);
free(rr);
goto next;
}
break;
case TXT_Resource_RecordType:
rc = get_TXT_Record(&(rr->rd_data.txt_record.txt_data), q->qName);
if (rc < 0) {
if (!get_TXT_Record(&(rr->rd_data.txt_record.txt_data), q->qName)) {
free(rr->name);
free(rr);
goto next;
Expand Down Expand Up @@ -549,10 +544,11 @@ void resolve_query(struct Message *msg)
}
}

/* @return 0 upon failure, 1 upon success */
int encode_resource_records(struct ResourceRecord *rr, uint8_t **buffer)
/* @return false upon failure, true upon success */
bool encode_resource_records(struct ResourceRecord *rr, uint8_t **buffer)
{
int i;

while (rr) {
// Answer questions by attaching resource sections.
encode_domain_name(buffer, rr->name);
Expand All @@ -563,11 +559,11 @@ int encode_resource_records(struct ResourceRecord *rr, uint8_t **buffer)

switch (rr->type) {
case A_Resource_RecordType:
for (i = 0; i < 4; ++i)
for (i = 0; i < 4; i += 1)
put8bits(buffer, rr->rd_data.a_record.addr[i]);
break;
case AAAA_Resource_RecordType:
for (i = 0; i < 16; ++i)
for (i = 0; i < 16; i += 1)
put8bits(buffer, rr->rd_data.aaaa_record.addr[i]);
break;
case TXT_Resource_RecordType:
Expand All @@ -577,24 +573,21 @@ int encode_resource_records(struct ResourceRecord *rr, uint8_t **buffer)
break;
default:
fprintf(stderr, "Unknown type %u. => Ignore resource record.\n", rr->type);
return 1;
return false;
}

rr = rr->next;
}

return 0;
return true;
}

/* @return 0 upon failure, 1 upon success */
int encode_msg(struct Message *msg, uint8_t **buffer)
/* @return false upon failure, true upon success */
bool encode_msg(struct Message *msg, uint8_t **buffer)
{
struct Question *q;
int rc;

encode_header(msg, buffer);

q = msg->questions;
struct Question *q = msg->questions;
while (q) {
encode_domain_name(buffer, q->qName);
put16bits(buffer, q->qType);
Expand All @@ -603,12 +596,19 @@ int encode_msg(struct Message *msg, uint8_t **buffer)
q = q->next;
}

rc = 0;
rc |= encode_resource_records(msg->answers, buffer);
rc |= encode_resource_records(msg->authorities, buffer);
rc |= encode_resource_records(msg->additionals, buffer);
if (!encode_resource_records(msg->answers, buffer)) {
return false;
}

return rc;
if (!encode_resource_records(msg->authorities, buffer)) {
return false;
}

if (!encode_resource_records(msg->additionals, buffer)) {
return false;
}

return true;
}

void free_resource_records(struct ResourceRecord *rr)
Expand Down Expand Up @@ -638,7 +638,7 @@ void free_questions(struct Question *qq)
int main()
{
// buffer for input/output binary packet
uint8_t buffer[BUF_SIZE];
uint8_t buffer[BUFFER_SIZE];
struct sockaddr_in client_addr;
socklen_t addr_len = sizeof(struct sockaddr_in);
struct sockaddr_in addr;
Expand Down Expand Up @@ -675,7 +675,13 @@ int main()
/* Receive DNS query */
nbytes = recvfrom(sock, buffer, sizeof(buffer), 0, (struct sockaddr *) &client_addr, &addr_len);

if (decode_msg(&msg, buffer, nbytes) != 0) {
/* failed to read query */
if (nbytes < 0) {
continue;
}

/* Try to decode query */
if (!decode_msg(&msg, buffer, nbytes)) {
continue;
}

Expand All @@ -689,12 +695,12 @@ int main()
print_message(&msg);

uint8_t *p = buffer;
if (encode_msg(&msg, &p) != 0) {
if (!encode_msg(&msg, &p)) {
continue;
}

/* Send DNS response */
int buflen = p - buffer;
size_t buflen = p - buffer;
sendto(sock, buffer, buflen, 0, (struct sockaddr*) &client_addr, addr_len);
}
}

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