mirror of
https://code.semirocket.science/wrapsix
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Dropped deprecated dnsproxy
This commit is contained in:
xHire
parent
148b644a70
commit
2f11edb447
477
src/dnsproxy.c
477
src/dnsproxy.c
@ -1,477 +0,0 @@
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/*
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* WrapSix
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* Copyright (C) 2008-2010 xHire <xhire@wrapsix.org>
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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 General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <netinet/in.h>
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#include <arpa/inet.h> /* inet_pton */
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#include <unistd.h> /* close */
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#include <string.h> /* memcpy */
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#include <stdlib.h> /* malloc */
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struct s_dns_header {
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unsigned short id; /* 16 b; identifier of a request */
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unsigned short flags; /* 16 b */
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unsigned short question; /* 16 b; num of data in question sec */
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unsigned short answer; /* 16 b; num of RRs in answer sec */
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unsigned short auth; /* 16 b; num of RRs in authority sec */
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unsigned short add; /* 16 b; num of RRs in additional sec */
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} __attribute__ ((__packed__));
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struct s_dns_answer {
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char *fqdn; /* domain name of the record */
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unsigned short dnlength; /* length of the domain name */
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unsigned short type; /* 16 b; RR type code */
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unsigned short class; /* 16 b; class of the data in rdata */
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unsigned int ttl; /* 32 b; RR caching interval */
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unsigned short rdlength; /* 16 b; length of the rdata section */
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char *rdata; /* describes the resource */
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} __attribute__ ((__packed__));
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#define BUFFER_SIZE 512 /* maximum of a DNS packet */
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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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int resolver_connect(int *sock, struct sockaddr_in6 *sock_addr);
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int udp_receive(int *sock, struct sockaddr_in6 *sock_addr, char *buffer, int *length);
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int udp_send(int *sock, struct sockaddr_in6 *sock_addr, char *data, int length);
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int lookup(unsigned short qtype, char *data, struct s_dns_answer **answer, unsigned short *answer_count);
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int get_fqdn(char *fqdn, char *data, unsigned short *length);
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int resolver_connect(int *sock, struct sockaddr_in6 *sock_addr)
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{
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int tmp_sock;
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struct sockaddr_in6 tmp_sock_addr;
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char resolver[] = RESOLVER;
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/* create a socket */
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if ((tmp_sock = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
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fprintf(stderr, "[Error] Unable to create UDP socket for outgoing connections\n");
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return 1;
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}
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/* setup the socket */
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tmp_sock_addr.sin6_family = AF_INET6;
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tmp_sock_addr.sin6_port = htons(PORT);
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inet_pton(AF_INET6, (char *) &resolver, &(tmp_sock_addr.sin6_addr));
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/* return correct data */
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memcpy(sock, &tmp_sock, sizeof(int));
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memcpy(sock_addr, &tmp_sock_addr, sizeof(struct sockaddr_in6));
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return 0;
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}
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int udp_receive(int *sock, struct sockaddr_in6 *sock_addr, char *buffer, int *length)
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{
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int tmp_length;
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int addrlen;
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addrlen = sizeof(struct sockaddr_in6);
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if ((tmp_length = recvfrom(*sock, buffer, BUFFER_SIZE, 0, (struct sockaddr *) sock_addr, (socklen_t *) &addrlen)) == -1) {
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char str_ip[128];
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inet_ntop(AF_INET6, &(sock_addr->sin6_addr), (char *) &str_ip, 128);
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fprintf(stderr, "[Error] Unable to read from UDP socket [%s]:%d\n", str_ip, PORT);
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return 1;
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}
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memcpy(length, &tmp_length, sizeof(int));
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return 0;
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}
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int udp_send(int *sock, struct sockaddr_in6 *sock_addr, char *data, int length)
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{
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int addrlen;
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addrlen = sizeof(struct sockaddr_in6);
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if (sendto(*sock, data, length, 0, (struct sockaddr *) sock_addr, addrlen) != length) {
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char str_ip[128];
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inet_ntop(AF_INET6, &(sock_addr->sin6_addr), (char *) &str_ip, 128);
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fprintf(stderr, "[Error] Unable to write to UDP socket [%s]:%d\n", str_ip, PORT);
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return 1;
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}
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return 0;
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}
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int lookup(unsigned short qtype, char *data, struct s_dns_answer **answer, unsigned short *answer_count)
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{
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int i, j;
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unsigned short length;
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unsigned short qclass;
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int resolver_sock;
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struct sockaddr_in6 resolver_sock_addr;
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char buffer[BUFFER_SIZE];
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struct s_dns_header *header;
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struct s_dns_answer *answers;
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header = (struct s_dns_header *) &buffer;
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/* create the request */
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header->id = htons(++id);
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header->flags = htons(0x0100); /* recursion desired */
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header->question = htons(1);
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header->answer = 0;
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header->auth = 0;
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header->add = 0;
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/* copy the fqdn from 'data' */
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for (i = sizeof(struct s_dns_header), length = i, j = 0;; i++, j++) {
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buffer[i] = data[j];
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if (length == i) {
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length += buffer[i] + 1;
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if (buffer[i] == 0x0) {
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break;
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}
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}
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}
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/* set the rest fields of the question section */
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qtype = htons(qtype);
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qclass = htons(0x1);
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memcpy(&buffer[i + 1], &qtype, 2);
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memcpy(&buffer[i + 3], &qclass, 2);
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/* create a connection socket */
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resolver_connect(&resolver_sock, &resolver_sock_addr);
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/* send the request */
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udp_send(&resolver_sock, &resolver_sock_addr, (char *) &buffer, i + 5);
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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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/* process the answer */
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header = (struct s_dns_header *) &buffer;
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header->answer = htons(header->answer);
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if (htons(header->id) == id && header->answer > 0) {
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if ((answers = (struct s_dns_answer *) malloc(header->answer * sizeof(struct s_dns_answer))) == NULL) {
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fprintf(stderr, "[Error] Lack of free memory\n");
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return 1;
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}
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/* save the count of the answers */
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memcpy(answer_count, &header->answer, sizeof(unsigned short));
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/* first go over the question section */
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j = sizeof(struct s_dns_header);
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if (htons(header->question) > 0) {
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while (buffer[j] != 0x0) {
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j += buffer[j] + 1;
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}
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/* set the position of answer section */
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j += 5;
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}
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/* go through all answers and process them */
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for (i = 0; i < header->answer; i++) {
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/* is the answer compressed? save the fqdn in both cases */
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if (buffer[j] & 0xc0) {
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get_fqdn((char *) &(answers[i].fqdn), &buffer[(int) buffer[j + 1]], &(answers[i].dnlength));
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j += 2;
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} else {
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get_fqdn((char *) &(answers[i].fqdn), &buffer[j], &(answers[i].dnlength));
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j += answers[i].dnlength;
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}
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/* save the rest of the answer */
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memcpy(&(answers[i].type), &buffer[j], 2);
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memcpy(&(answers[i].class), &buffer[j + 2], 2);
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memcpy(&(answers[i].ttl), &buffer[j + 4], 4);
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memcpy(&(answers[i].rdlength), &buffer[j + 8], 2);
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answers[i].rdlength = htons(answers[i].rdlength);
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if ((answers[i].rdata = (char *) malloc(answers[i].rdlength)) == NULL) {
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fprintf(stderr, "[Error] Lack of free memory\n");
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return 1;
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}
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memcpy(answers[i].rdata, &buffer[j + 10], answers[i].rdlength);
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j += 10 + answers[i].rdlength;
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}
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/* return address of array of answers */
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memcpy(answer, &answers, sizeof(struct s_dns_answer *));
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} else {
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return 1;
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}
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return 0;
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}
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int get_fqdn(char *fqdn, char *data, unsigned short *length)
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{
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unsigned short i, offset;
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char buffer[BUFFER_SIZE];
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char *tmp;
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offset = 0;
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/* read the fqdn and save it into the buffer */
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for (i = 0; data[i] != 0x0; i++) {
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buffer[i] = data[i];
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if (i == offset) {
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offset += data[i] + 1;
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}
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}
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/* don't forget to add the ending octet */
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buffer[offset] = 0x0;
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offset++;
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/* create a storage to save the fqdn */
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if ((tmp = (char *) malloc(offset)) == NULL) {
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fprintf(stderr, "[Error] Lack of free memory\n");
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return 1;
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}
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/* save length of the fqdn */
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memcpy(length, &offset, sizeof(unsigned short));
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/* save the fqdn */
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memcpy(tmp, &buffer, *length);
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/* save the address of the storage of the fqdn */
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memcpy(fqdn, &tmp, sizeof(char *));
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return 0;
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}
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int main(int argc, char **argv)
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{
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int i, j;
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int length, offset;
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unsigned short k;
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unsigned short answer_count;
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char ip[] = IP;
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char buffer[BUFFER_SIZE];
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char buffer_answer[BUFFER_SIZE];
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int sock;
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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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return 1;
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}
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/* setup the socket */
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sock_addr.sin6_family = AF_INET6;
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sock_addr.sin6_port = htons(PORT);
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inet_pton(AF_INET6, (char *) &ip, &(sock_addr.sin6_addr));
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/* bind the socket to address and port */
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if (bind(sock, (struct sockaddr *) &(sock_addr), sizeof(sock_addr)) == -1) {
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fprintf(stderr, "[Error] Unable to bind UDP socket to %s:%d\n", IP, PORT);
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return 1;
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}
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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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/* 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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/* 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 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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/* 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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/* 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 the request */
|
||||
udp_send(&resolver_sock, &resolver_sock_addr, (char *) &buffer, length);
|
||||
|
||||
/* fetch the answer */
|
||||
udp_receive(&resolver_sock, &resolver_sock_addr, (char *) &buffer, (int *) &length);
|
||||
|
||||
/* close the socket */
|
||||
close(resolver_sock);
|
||||
|
||||
|
||||
/* forward the answer to the client */
|
||||
udp_send(&sock, &client_sock_addr, (char *) &buffer, length);
|
||||
}
|
||||
}
|
||||
|
||||
/* final clean-up */
|
||||
close(sock);
|
||||
|
||||
return 0;
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user