mirror of
https://code.semirocket.science/wrapsix
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Synthesing AAAA records from A ones
Leaving all other types of records to be 'just processed' Running in an infinite loop
This commit is contained in:
Michal Zima
parent
8968ffedb3
commit
e7046c4ea3
204
src/dnsproxy.c
204
src/dnsproxy.c
@ -1,6 +1,6 @@
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/*
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* WrapSix
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* Copyright (C) 2008-2009 Michal Zima <xhire@mujmalysvet.cz>
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* Copyright (C) 2008-2010 Michal Zima <xhire@mujmalysvet.cz>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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@ -46,6 +46,7 @@ struct s_dns_answer {
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#define IP "::2"
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#define RESOLVER "::1"
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#define PORT 53
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#define PREFIX "::"
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unsigned short id = 0;
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@ -283,10 +284,18 @@ int main(int argc, char **argv)
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struct sockaddr_in6 sock_addr,
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client_sock_addr;
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int resolver_sock;
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struct sockaddr_in6 resolver_sock_addr;
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struct s_dns_header *dns, *dns_answer;
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unsigned short qtype, qclass;
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struct s_dns_answer *answers;
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struct in6_addr ipv6_prefix;
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/* initialization */
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inet_pton(AF_INET6, PREFIX, &ipv6_prefix);
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/* create the socket */
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if ((sock = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
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fprintf(stderr, "[Error] Unable to create UDP socket\n");
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@ -304,69 +313,160 @@ int main(int argc, char **argv)
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return 1;
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}
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/* fetch a request */
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udp_receive(&sock, &client_sock_addr, (char *) &buffer, &length);
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for (;;) {
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/* fetch a request */
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udp_receive(&sock, &client_sock_addr, (char *) &buffer, &length);
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/* process the request */
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dns = (struct s_dns_header *) &buffer;
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/* TODO: there could be more than one question */
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offset = sizeof(struct s_dns_header);
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while (buffer[offset] != 0x0) {
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offset += buffer[offset] + 1;
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}
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memcpy(&qtype, &buffer[offset + 1], 2);
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memcpy(&qclass, &buffer[offset + 3], 2);
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qtype = htons(qtype);
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qclass = htons(qclass);
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/* process the request */
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dns = (struct s_dns_header *) &buffer;
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/* TODO: there could be more than one question */
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offset = sizeof(struct s_dns_header);
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while (buffer[offset] != 0x0) {
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offset += buffer[offset] + 1;
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}
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memcpy(&qtype, &buffer[offset + 1], 2);
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memcpy(&qclass, &buffer[offset + 3], 2);
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qtype = htons(qtype);
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qclass = htons(qclass);
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/* this is AAAA request */
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if (qclass == 0x1 && qtype == 0x1c) {
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answers = NULL;
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/* first look up if some AAAA exists */
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if (lookup(0x1c, &buffer[sizeof(struct s_dns_header)], &answers, &answer_count) == 0) {
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/* send back an answer */
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dns_answer = (struct s_dns_header *) &buffer_answer;
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dns_answer->id = dns->id;
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dns_answer->flags = htons(0x8180);
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dns_answer->question = htons(1);
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dns_answer->answer = htons(answer_count);
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dns_answer->auth = 0;
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dns_answer->add = 0;
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/* this is AAAA request */
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if (qclass == 0x1 && qtype == 0x1c) {
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answers = NULL;
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/* first look up if some AAAA exists */
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if (lookup(0x1c, &buffer[sizeof(struct s_dns_header)], &answers, &answer_count) == 0) {
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/* send back an answer */
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dns_answer = (struct s_dns_header *) &buffer_answer;
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dns_answer->id = dns->id;
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dns_answer->flags = htons(0x8180);
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dns_answer->question = htons(1);
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dns_answer->answer = htons(answer_count);
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dns_answer->auth = 0;
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dns_answer->add = 0;
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/* copy question section */
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i = offset - sizeof(struct s_dns_header) + 5;
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memcpy(&buffer_answer[sizeof(struct s_dns_header)], &buffer[sizeof(struct s_dns_header)], i);
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/* copy question section */
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i = offset - sizeof(struct s_dns_header) + 5;
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memcpy(&buffer_answer[sizeof(struct s_dns_header)], &buffer[sizeof(struct s_dns_header)], i);
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/* construct answer section */
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i = offset + 5;
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for (j = 0; j < answer_count; j++) {
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/* copy fqdn */
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memcpy(&buffer_answer[i], answers[j].fqdn, answers[j].dnlength);
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i += answers[j].dnlength;
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/* construct answer section */
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i = offset + 5;
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for (j = 0; j < answer_count; j++) {
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/* copy fqdn */
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memcpy(&buffer_answer[i], answers[j].fqdn, answers[j].dnlength);
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i += answers[j].dnlength;
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/* copy type, class and ttl */
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memcpy(&buffer_answer[i], &(answers[j].type), 2 * sizeof(unsigned short) + sizeof(unsigned int));
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i += 2 * sizeof(unsigned short) + sizeof(unsigned int);
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/* copy type, class and ttl */
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memcpy(&buffer_answer[i], &(answers[j].type), 2 * sizeof(unsigned short) + sizeof(unsigned int));
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i += 2 * sizeof(unsigned short) + sizeof(unsigned int);
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/* copy rdlength */
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k = htons(answers[j].rdlength);
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memcpy(&buffer_answer[i], &k, sizeof(unsigned short));
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i += sizeof(unsigned short);
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/* copy rdlength */
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k = htons(answers[j].rdlength);
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memcpy(&buffer_answer[i], &k, sizeof(unsigned short));
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i += sizeof(unsigned short);
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/* copy rdata */
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memcpy(&buffer_answer[i], answers[j].rdata, answers[j].rdlength);
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i += answers[j].rdlength;
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/* copy rdata */
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memcpy(&buffer_answer[i], answers[j].rdata, answers[j].rdlength);
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i += answers[j].rdlength;
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/* memory clean-up */
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free(answers[j].fqdn);
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free(answers[j].rdata);
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}
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/* send it */
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udp_send(&sock, &client_sock_addr, (char *) &buffer_answer, i);
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/* memory clean-up */
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free(answers[j].fqdn);
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free(answers[j].rdata);
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free(answers);
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/* second look up if some A exists & transform it */
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} else if (lookup(0x1, &buffer[sizeof(struct s_dns_header)], &answers, &answer_count) == 0) {
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/* send back an answer */
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dns_answer = (struct s_dns_header *) &buffer_answer;
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dns_answer->id = dns->id;
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dns_answer->flags = htons(0x8180);
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dns_answer->question = htons(1);
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dns_answer->answer = htons(answer_count);
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dns_answer->auth = 0;
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dns_answer->add = 0;
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/* copy question section */
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i = offset - sizeof(struct s_dns_header) + 5;
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memcpy(&buffer_answer[sizeof(struct s_dns_header)], &buffer[sizeof(struct s_dns_header)], i);
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/* construct answer section */
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i = offset + 5;
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for (j = 0; j < answer_count; j++) {
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/* copy fqdn */
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memcpy(&buffer_answer[i], answers[j].fqdn, answers[j].dnlength);
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i += answers[j].dnlength;
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/* set type */
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k = htons(0x1c);
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memcpy(&buffer_answer[i], &k, sizeof(unsigned short));
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i += sizeof(unsigned short);
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/* copy class and ttl */
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memcpy(&buffer_answer[i], &(answers[j].class), sizeof(unsigned short) + sizeof(unsigned int));
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i += sizeof(unsigned short) + sizeof(unsigned int);
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/* set rdlength */
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k = htons(sizeof(ipv6_prefix));
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memcpy(&buffer_answer[i], &k, sizeof(unsigned short));
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i += sizeof(unsigned short);
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/* copy IPv6 prefix */
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memcpy(&buffer_answer[i], &ipv6_prefix, sizeof(ipv6_prefix) - answers[j].rdlength);
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i += sizeof(ipv6_prefix) - answers[j].rdlength;
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/* copy IPv4 address */
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memcpy(&buffer_answer[i], answers[j].rdata, answers[j].rdlength);
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i += answers[j].rdlength;
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/* memory clean-up */
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free(answers[j].fqdn);
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free(answers[j].rdata);
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}
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/* send it */
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udp_send(&sock, &client_sock_addr, (char *) &buffer_answer, i);
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/* memory clean-up */
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free(answers);
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/* third say we have no clue about the fqdn */
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} else {
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/* send back an answer */
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dns_answer = (struct s_dns_header *) &buffer_answer;
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dns_answer->id = dns->id;
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dns_answer->flags = htons(0x8183);
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dns_answer->question = htons(1);
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dns_answer->answer = 0;
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dns_answer->auth = 0;
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dns_answer->add = 0;
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/* copy question section */
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i = offset - sizeof(struct s_dns_header) + 5;
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memcpy(&buffer_answer[sizeof(struct s_dns_header)], &buffer[sizeof(struct s_dns_header)], i);
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i += sizeof(struct s_dns_header);
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/* send it */
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udp_send(&sock, &client_sock_addr, (char *) &buffer_answer, i);
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}
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/* this is other than AAAA request -> just proxy it */
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} else {
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/* create a connection socket */
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resolver_connect(&resolver_sock, &resolver_sock_addr);
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/* send it */
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udp_send(&sock, &client_sock_addr, (char *) &buffer_answer, i);
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/* send the request */
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udp_send(&resolver_sock, &resolver_sock_addr, (char *) &buffer, length);
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/* memory clean-up */
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free(answers);
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/* fetch the answer */
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udp_receive(&resolver_sock, &resolver_sock_addr, (char *) &buffer, (int *) &length);
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/* close the socket */
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close(resolver_sock);
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/* forward the answer to the client */
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udp_send(&sock, &client_sock_addr, (char *) &buffer, length);
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}
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}
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