mirror of https://github.com/M66B/NetGuard.git
Native refactoring
This commit is contained in:
M66B
parent
3beb851339
commit
dc0980e87f
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@ -0,0 +1,143 @@
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/*
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This file is part of NetGuard.
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NetGuard 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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NetGuard 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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You should have received a copy of the GNU General Public License
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along with NetGuard. If not, see <http://www.gnu.org/licenses/>.
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Copyright 2015-2016 by Marcel Bokhorst (M66B)
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*/
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#include "netguard.h"
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int check_dhcp(const struct arguments *args, const struct udp_session *u,
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const uint8_t *data, const size_t datalen) {
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// This is untested
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// Android routing of DHCP is erroneous
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log_android(ANDROID_LOG_WARN, "DHCP check");
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if (datalen < sizeof(struct dhcp_packet)) {
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log_android(ANDROID_LOG_WARN, "DHCP packet size %d", datalen);
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return -1;
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}
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const struct dhcp_packet *request = (struct dhcp_packet *) data;
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if (ntohl(request->option_format) != DHCP_OPTION_MAGIC_NUMBER) {
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log_android(ANDROID_LOG_WARN, "DHCP invalid magic %x", request->option_format);
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return -1;
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}
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if (request->htype != 1 || request->hlen != 6) {
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log_android(ANDROID_LOG_WARN, "DHCP unknown hardware htype %d hlen %d",
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request->htype, request->hlen);
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return -1;
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}
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log_android(ANDROID_LOG_WARN, "DHCP opcode", request->opcode);
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// Discover: source 0.0.0.0:68 destination 255.255.255.255:67
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// Offer: source 10.1.10.1:67 destination 255.255.255.255:68
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// Request: source 0.0.0.0:68 destination 255.255.255.255:67
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// Ack: source: 10.1.10.1 destination: 255.255.255.255
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if (request->opcode == 1) { // Discover/request
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struct dhcp_packet *response = calloc(500, 1);
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// Hack
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inet_pton(AF_INET, "10.1.10.1", &u->saddr);
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/*
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Discover:
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DHCP option 53: DHCP Discover
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DHCP option 50: 192.168.1.100 requested
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DHCP option 55: Parameter Request List:
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Request Subnet Mask (1), Router (3), Domain Name (15), Domain Name Server (6)
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Request
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DHCP option 53: DHCP Request
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DHCP option 50: 192.168.1.100 requested
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DHCP option 54: 192.168.1.1 DHCP server.
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*/
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memcpy(response, request, sizeof(struct dhcp_packet));
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response->opcode = (uint8_t) (request->siaddr == 0 ? 2 /* Offer */ : /* Ack */ 4);
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response->secs = 0;
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response->flags = 0;
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memset(&response->ciaddr, 0, sizeof(response->ciaddr));
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inet_pton(AF_INET, "10.1.10.2", &response->yiaddr);
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inet_pton(AF_INET, "10.1.10.1", &response->siaddr);
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memset(&response->giaddr, 0, sizeof(response->giaddr));
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// https://tools.ietf.org/html/rfc2132
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uint8_t *options = (uint8_t *) (response + sizeof(struct dhcp_packet));
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int idx = 0;
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*(options + idx++) = 53; // Message type
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*(options + idx++) = 1;
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*(options + idx++) = (uint8_t) (request->siaddr == 0 ? 2 : 5);
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/*
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1 DHCPDISCOVER
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2 DHCPOFFER
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3 DHCPREQUEST
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4 DHCPDECLINE
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5 DHCPACK
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6 DHCPNAK
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7 DHCPRELEASE
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8 DHCPINFORM
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*/
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*(options + idx++) = 1; // subnet mask
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*(options + idx++) = 4; // IP4 length
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inet_pton(AF_INET, "255.255.255.0", options + idx);
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idx += 4;
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*(options + idx++) = 3; // gateway
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*(options + idx++) = 4; // IP4 length
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inet_pton(AF_INET, "10.1.10.1", options + idx);
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idx += 4;
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*(options + idx++) = 51; // lease time
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*(options + idx++) = 4; // quad
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*((uint32_t *) (options + idx)) = 3600;
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idx += 4;
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*(options + idx++) = 54; // DHCP
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*(options + idx++) = 4; // IP4 length
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inet_pton(AF_INET, "10.1.10.1", options + idx);
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idx += 4;
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*(options + idx++) = 6; // DNS
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*(options + idx++) = 4; // IP4 length
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inet_pton(AF_INET, "8.8.8.8", options + idx);
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idx += 4;
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*(options + idx++) = 255; // End
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/*
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DHCP option 53: DHCP Offer
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DHCP option 1: 255.255.255.0 subnet mask
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DHCP option 3: 192.168.1.1 router
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DHCP option 51: 86400s (1 day) IP address lease time
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DHCP option 54: 192.168.1.1 DHCP server
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DHCP option 6: DNS servers 9.7.10.15
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*/
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write_udp(args, u, (uint8_t *) response, 500);
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free(response);
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}
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return 0;
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}
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@ -0,0 +1,252 @@
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/*
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This file is part of NetGuard.
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NetGuard 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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NetGuard 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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You should have received a copy of the GNU General Public License
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along with NetGuard. If not, see <http://www.gnu.org/licenses/>.
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Copyright 2015-2016 by Marcel Bokhorst (M66B)
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*/
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#include "netguard.h"
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int32_t get_qname(const uint8_t *data, const size_t datalen, uint16_t off, char *qname) {
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*qname = 0;
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uint16_t c = 0;
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uint8_t noff = 0;
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uint16_t ptr = off;
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uint8_t len = *(data + ptr);
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uint8_t parts = 0;
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while (len && parts < 10) {
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parts++;
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if (len & 0xC0) {
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ptr = (uint16_t) ((len & 0x3F) * 256 + *(data + ptr + 1));
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len = *(data + ptr);
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log_android(ANDROID_LOG_DEBUG, "DNS qname compression ptr %d len %d", ptr, len);
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if (!c) {
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c = 1;
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off += 2;
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}
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}
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else if (ptr + 1 + len <= datalen) {
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memcpy(qname + noff, data + ptr + 1, len);
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*(qname + noff + len) = '.';
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noff += (len + 1);
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ptr += (len + 1);
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len = *(data + ptr);
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}
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else
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break;
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}
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ptr++;
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if (len > 0 || noff == 0) {
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log_android(ANDROID_LOG_ERROR, "DNS qname invalid len %d noff %d part %d", len, noff,
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parts);
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return -1;
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}
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*(qname + noff - 1) = 0;
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return (c ? off : ptr);
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}
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void parse_dns_response(const struct arguments *args, const uint8_t *data, const size_t datalen) {
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if (datalen < sizeof(struct dns_header) + 1) {
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log_android(ANDROID_LOG_WARN, "DNS response length %d", datalen);
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return;
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}
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// Check if standard DNS query
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// TODO multiple qnames
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const struct dns_header *dns = (struct dns_header *) data;
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int qcount = ntohs(dns->q_count);
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int acount = ntohs(dns->ans_count);
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if (dns->qr == 1 && dns->opcode == 0 && qcount > 0 && acount > 0) {
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log_android(ANDROID_LOG_DEBUG, "DNS response qcount %d acount %d", qcount, acount);
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if (qcount > 1)
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log_android(ANDROID_LOG_WARN, "DNS response qcount %d acount %d", qcount, acount);
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// http://tools.ietf.org/html/rfc1035
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char qname[DNS_QNAME_MAX + 1];
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char name[DNS_QNAME_MAX + 1];
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int32_t off = sizeof(struct dns_header);
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for (int q = 0; q < qcount; q++) {
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off = get_qname(data, datalen, (uint16_t) off, name);
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if (off > 0 && off + 4 <= datalen) {
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uint16_t qtype = ntohs(*((uint16_t *) (data + off)));
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uint16_t qclass = ntohs(*((uint16_t *) (data + off + 2)));
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log_android(ANDROID_LOG_DEBUG,
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"DNS question %d qtype %d qclass %d qname %s",
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q, qtype, qclass, name);
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off += 4;
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// TODO multiple qnames?
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if (q == 0)
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strcpy(qname, name);
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}
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else {
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log_android(ANDROID_LOG_WARN,
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"DNS response Q invalid off %d datalen %d",
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off, datalen);
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return;
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}
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}
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for (int a = 0; a < acount; a++) {
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off = get_qname(data, datalen, (uint16_t) off, name);
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if (off > 0 && off + 10 <= datalen) {
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uint16_t qtype = ntohs(*((uint16_t *) (data + off)));
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uint16_t qclass = ntohs(*((uint16_t *) (data + off + 2)));
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uint32_t ttl = ntohl(*((uint32_t *) (data + off + 4)));
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uint16_t rdlength = ntohs(*((uint16_t *) (data + off + 8)));
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off += 10;
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if (off + rdlength <= datalen) {
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if (qclass == DNS_QCLASS_IN &&
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(qtype == DNS_QTYPE_A || qtype == DNS_QTYPE_AAAA)) {
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char rd[INET6_ADDRSTRLEN + 1];
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if (qtype == DNS_QTYPE_A)
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inet_ntop(AF_INET, data + off, rd, sizeof(rd));
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else if (qclass == DNS_QCLASS_IN && qtype == DNS_QTYPE_AAAA)
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inet_ntop(AF_INET6, data + off, rd, sizeof(rd));
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dns_resolved(args, qname, name, rd, ttl);
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log_android(ANDROID_LOG_DEBUG,
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"DNS answer %d qname %s qtype %d ttl %d data %s",
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a, name, qtype, ttl, rd);
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} else
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log_android(ANDROID_LOG_DEBUG,
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"DNS answer %d qname %s qclass %d qtype %d ttl %d length %d",
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a, name, qclass, qtype, ttl, rdlength);
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off += rdlength;
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}
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else {
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log_android(ANDROID_LOG_WARN,
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"DNS response A invalid off %d rdlength %d datalen %d",
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off, rdlength, datalen);
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return;
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}
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}
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else {
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log_android(ANDROID_LOG_WARN,
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"DNS response A invalid off %d datalen %d",
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off, datalen);
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return;
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}
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}
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}
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else if (acount > 0)
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log_android(ANDROID_LOG_WARN,
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"DNS response qr %d opcode %d qcount %d acount %d",
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dns->qr, dns->opcode, qcount, acount);
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}
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int get_dns_query(const struct arguments *args, const struct udp_session *u,
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const uint8_t *data, const size_t datalen,
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uint16_t *qtype, uint16_t *qclass, char *qname) {
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if (datalen < sizeof(struct dns_header) + 1) {
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log_android(ANDROID_LOG_WARN, "DNS query length %d", datalen);
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return -1;
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}
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// Check if standard DNS query
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// TODO multiple qnames
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const struct dns_header *dns = (struct dns_header *) data;
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int qcount = ntohs(dns->q_count);
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if (dns->qr == 0 && dns->opcode == 0 && qcount > 0) {
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if (qcount > 1)
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log_android(ANDROID_LOG_WARN, "DNS query qcount %d", qcount);
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// http://tools.ietf.org/html/rfc1035
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int off = get_qname(data, datalen, sizeof(struct dns_header), qname);
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if (off > 0 && off + 4 == datalen) {
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*qtype = ntohs(*((uint16_t *) (data + off)));
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*qclass = ntohs(*((uint16_t *) (data + off + 2)));
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return 0;
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}
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else
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log_android(ANDROID_LOG_WARN, "DNS query invalid off %d datalen %d", off, datalen);
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}
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return -1;
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}
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int check_domain(const struct arguments *args, const struct udp_session *u,
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const uint8_t *data, const size_t datalen,
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uint16_t qclass, uint16_t qtype, const char *name) {
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if (qclass == DNS_QCLASS_IN &&
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(qtype == DNS_QTYPE_A || qtype == DNS_QTYPE_AAAA) &&
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is_domain_blocked(args, name)) {
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log_android(ANDROID_LOG_INFO, "DNS query type %d name %s blocked", qtype, name);
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// Build response
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size_t rlen = datalen + sizeof(struct dns_rr) + (qtype == DNS_QTYPE_A ? 4 : 16);
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uint8_t *response = malloc(rlen);
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// Copy header & query
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memcpy(response, data, datalen);
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// Modify copied header
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struct dns_header *rh = (struct dns_header *) response;
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rh->qr = 1;
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rh->aa = 0;
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rh->tc = 0;
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rh->rd = 0;
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rh->ra = 0;
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rh->z = 0;
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rh->ad = 0;
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rh->cd = 0;
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rh->rcode = 0;
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rh->ans_count = htons(1);
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rh->auth_count = 0;
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rh->add_count = 0;
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// Build answer
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struct dns_rr *answer = (struct dns_rr *) (response + datalen);
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answer->qname_ptr = htons(sizeof(struct dns_header) | 0xC000);
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answer->qtype = htons(qtype);
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answer->qclass = htons(qclass);
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answer->ttl = htonl(DNS_TTL);
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answer->rdlength = htons(qtype == DNS_QTYPE_A ? 4 : 16);
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// Add answer address
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uint8_t *addr = response + datalen + sizeof(struct dns_rr);
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if (qtype == DNS_QTYPE_A)
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inet_pton(AF_INET, "127.0.0.1", addr);
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else
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inet_pton(AF_INET6, "::1", addr);
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// Experiment
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rlen = datalen;
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rh->rcode = 3; // NXDOMAIN
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rh->ans_count = 0;
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// Send response
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if (write_udp(args, u, response, rlen) < 0)
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log_android(ANDROID_LOG_WARN, "UDP DNS write error %d: %s", errno, strerror(errno));
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free(response);
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return 1;
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}
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return 0;
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}
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@ -190,144 +190,6 @@ void check_udp_sockets(const struct arguments *args, fd_set *rfds, fd_set *wfds,
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}
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}
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int32_t get_qname(const uint8_t *data, const size_t datalen, uint16_t off, char *qname) {
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*qname = 0;
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uint16_t c = 0;
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uint8_t noff = 0;
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uint16_t ptr = off;
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uint8_t len = *(data + ptr);
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uint8_t parts = 0;
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while (len && parts < 10) {
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parts++;
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if (len & 0xC0) {
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ptr = (uint16_t) ((len & 0x3F) * 256 + *(data + ptr + 1));
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len = *(data + ptr);
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log_android(ANDROID_LOG_DEBUG, "DNS qname compression ptr %d len %d", ptr, len);
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if (!c) {
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c = 1;
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off += 2;
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}
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||||
}
|
||||
else if (ptr + 1 + len <= datalen) {
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memcpy(qname + noff, data + ptr + 1, len);
|
||||
*(qname + noff + len) = '.';
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noff += (len + 1);
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|
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ptr += (len + 1);
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len = *(data + ptr);
|
||||
}
|
||||
else
|
||||
break;
|
||||
}
|
||||
ptr++;
|
||||
|
||||
if (len > 0 || noff == 0) {
|
||||
log_android(ANDROID_LOG_ERROR, "DNS qname invalid len %d noff %d part %d", len, noff,
|
||||
parts);
|
||||
return -1;
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}
|
||||
|
||||
*(qname + noff - 1) = 0;
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||||
|
||||
return (c ? off : ptr);
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||||
}
|
||||
|
||||
void parse_dns_response(const struct arguments *args, const uint8_t *data, const size_t datalen) {
|
||||
if (datalen < sizeof(struct dns_header) + 1) {
|
||||
log_android(ANDROID_LOG_WARN, "DNS response length %d", datalen);
|
||||
return;
|
||||
}
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||||
|
||||
// Check if standard DNS query
|
||||
// TODO multiple qnames
|
||||
const struct dns_header *dns = (struct dns_header *) data;
|
||||
int qcount = ntohs(dns->q_count);
|
||||
int acount = ntohs(dns->ans_count);
|
||||
if (dns->qr == 1 && dns->opcode == 0 && qcount > 0 && acount > 0) {
|
||||
log_android(ANDROID_LOG_DEBUG, "DNS response qcount %d acount %d", qcount, acount);
|
||||
if (qcount > 1)
|
||||
log_android(ANDROID_LOG_WARN, "DNS response qcount %d acount %d", qcount, acount);
|
||||
|
||||
// http://tools.ietf.org/html/rfc1035
|
||||
char qname[DNS_QNAME_MAX + 1];
|
||||
|
||||
char name[DNS_QNAME_MAX + 1];
|
||||
int32_t off = sizeof(struct dns_header);
|
||||
for (int q = 0; q < qcount; q++) {
|
||||
off = get_qname(data, datalen, (uint16_t) off, name);
|
||||
if (off > 0 && off + 4 <= datalen) {
|
||||
uint16_t qtype = ntohs(*((uint16_t *) (data + off)));
|
||||
uint16_t qclass = ntohs(*((uint16_t *) (data + off + 2)));
|
||||
log_android(ANDROID_LOG_DEBUG,
|
||||
"DNS question %d qtype %d qclass %d qname %s",
|
||||
q, qtype, qclass, name);
|
||||
off += 4;
|
||||
|
||||
// TODO multiple qnames?
|
||||
if (q == 0)
|
||||
strcpy(qname, name);
|
||||
}
|
||||
else {
|
||||
log_android(ANDROID_LOG_WARN,
|
||||
"DNS response Q invalid off %d datalen %d",
|
||||
off, datalen);
|
||||
return;
|
||||
}
|
||||
}
|
||||
|
||||
for (int a = 0; a < acount; a++) {
|
||||
off = get_qname(data, datalen, (uint16_t) off, name);
|
||||
if (off > 0 && off + 10 <= datalen) {
|
||||
uint16_t qtype = ntohs(*((uint16_t *) (data + off)));
|
||||
uint16_t qclass = ntohs(*((uint16_t *) (data + off + 2)));
|
||||
uint32_t ttl = ntohl(*((uint32_t *) (data + off + 4)));
|
||||
uint16_t rdlength = ntohs(*((uint16_t *) (data + off + 8)));
|
||||
off += 10;
|
||||
|
||||
if (off + rdlength <= datalen) {
|
||||
if (qclass == DNS_QCLASS_IN &&
|
||||
(qtype == DNS_QTYPE_A || qtype == DNS_QTYPE_AAAA)) {
|
||||
|
||||
char rd[INET6_ADDRSTRLEN + 1];
|
||||
if (qtype == DNS_QTYPE_A)
|
||||
inet_ntop(AF_INET, data + off, rd, sizeof(rd));
|
||||
else if (qclass == DNS_QCLASS_IN && qtype == DNS_QTYPE_AAAA)
|
||||
inet_ntop(AF_INET6, data + off, rd, sizeof(rd));
|
||||
|
||||
dns_resolved(args, qname, name, rd, ttl);
|
||||
log_android(ANDROID_LOG_DEBUG,
|
||||
"DNS answer %d qname %s qtype %d ttl %d data %s",
|
||||
a, name, qtype, ttl, rd);
|
||||
|
||||
} else
|
||||
log_android(ANDROID_LOG_DEBUG,
|
||||
"DNS answer %d qname %s qclass %d qtype %d ttl %d length %d",
|
||||
a, name, qclass, qtype, ttl, rdlength);
|
||||
|
||||
off += rdlength;
|
||||
}
|
||||
else {
|
||||
log_android(ANDROID_LOG_WARN,
|
||||
"DNS response A invalid off %d rdlength %d datalen %d",
|
||||
off, rdlength, datalen);
|
||||
return;
|
||||
}
|
||||
}
|
||||
else {
|
||||
log_android(ANDROID_LOG_WARN,
|
||||
"DNS response A invalid off %d datalen %d",
|
||||
off, datalen);
|
||||
return;
|
||||
}
|
||||
}
|
||||
}
|
||||
else if (acount > 0)
|
||||
log_android(ANDROID_LOG_WARN,
|
||||
"DNS response qr %d opcode %d qcount %d acount %d",
|
||||
dns->qr, dns->opcode, qcount, acount);
|
||||
}
|
||||
|
||||
int has_udp_session(const struct arguments *args, const uint8_t *pkt, const uint8_t *payload) {
|
||||
// Get headers
|
||||
const uint8_t version = (*pkt) >> 4;
|
||||
|
|
@ -558,223 +420,6 @@ jboolean handle_udp(const struct arguments *args,
|
|||
return 1;
|
||||
}
|
||||
|
||||
int get_dns_query(const struct arguments *args, const struct udp_session *u,
|
||||
const uint8_t *data, const size_t datalen,
|
||||
uint16_t *qtype, uint16_t *qclass, char *qname) {
|
||||
if (datalen < sizeof(struct dns_header) + 1) {
|
||||
log_android(ANDROID_LOG_WARN, "DNS query length %d", datalen);
|
||||
return -1;
|
||||
}
|
||||
|
||||
// Check if standard DNS query
|
||||
// TODO multiple qnames
|
||||
const struct dns_header *dns = (struct dns_header *) data;
|
||||
int qcount = ntohs(dns->q_count);
|
||||
if (dns->qr == 0 && dns->opcode == 0 && qcount > 0) {
|
||||
if (qcount > 1)
|
||||
log_android(ANDROID_LOG_WARN, "DNS query qcount %d", qcount);
|
||||
|
||||
// http://tools.ietf.org/html/rfc1035
|
||||
int off = get_qname(data, datalen, sizeof(struct dns_header), qname);
|
||||
if (off > 0 && off + 4 == datalen) {
|
||||
*qtype = ntohs(*((uint16_t *) (data + off)));
|
||||
*qclass = ntohs(*((uint16_t *) (data + off + 2)));
|
||||
return 0;
|
||||
}
|
||||
else
|
||||
log_android(ANDROID_LOG_WARN, "DNS query invalid off %d datalen %d", off, datalen);
|
||||
}
|
||||
|
||||
return -1;
|
||||
}
|
||||
|
||||
int check_domain(const struct arguments *args, const struct udp_session *u,
|
||||
const uint8_t *data, const size_t datalen,
|
||||
uint16_t qclass, uint16_t qtype, const char *name) {
|
||||
|
||||
if (qclass == DNS_QCLASS_IN &&
|
||||
(qtype == DNS_QTYPE_A || qtype == DNS_QTYPE_AAAA) &&
|
||||
is_domain_blocked(args, name)) {
|
||||
|
||||
log_android(ANDROID_LOG_INFO, "DNS query type %d name %s blocked", qtype, name);
|
||||
|
||||
// Build response
|
||||
size_t rlen = datalen + sizeof(struct dns_rr) + (qtype == DNS_QTYPE_A ? 4 : 16);
|
||||
uint8_t *response = malloc(rlen);
|
||||
|
||||
// Copy header & query
|
||||
memcpy(response, data, datalen);
|
||||
|
||||
// Modify copied header
|
||||
struct dns_header *rh = (struct dns_header *) response;
|
||||
rh->qr = 1;
|
||||
rh->aa = 0;
|
||||
rh->tc = 0;
|
||||
rh->rd = 0;
|
||||
rh->ra = 0;
|
||||
rh->z = 0;
|
||||
rh->ad = 0;
|
||||
rh->cd = 0;
|
||||
rh->rcode = 0;
|
||||
rh->ans_count = htons(1);
|
||||
rh->auth_count = 0;
|
||||
rh->add_count = 0;
|
||||
|
||||
// Build answer
|
||||
struct dns_rr *answer = (struct dns_rr *) (response + datalen);
|
||||
answer->qname_ptr = htons(sizeof(struct dns_header) | 0xC000);
|
||||
answer->qtype = htons(qtype);
|
||||
answer->qclass = htons(qclass);
|
||||
answer->ttl = htonl(DNS_TTL);
|
||||
answer->rdlength = htons(qtype == DNS_QTYPE_A ? 4 : 16);
|
||||
|
||||
// Add answer address
|
||||
uint8_t *addr = response + datalen + sizeof(struct dns_rr);
|
||||
if (qtype == DNS_QTYPE_A)
|
||||
inet_pton(AF_INET, "127.0.0.1", addr);
|
||||
else
|
||||
inet_pton(AF_INET6, "::1", addr);
|
||||
|
||||
// Experiment
|
||||
rlen = datalen;
|
||||
rh->rcode = 3; // NXDOMAIN
|
||||
rh->ans_count = 0;
|
||||
|
||||
// Send response
|
||||
if (write_udp(args, u, response, rlen) < 0)
|
||||
log_android(ANDROID_LOG_WARN, "UDP DNS write error %d: %s", errno, strerror(errno));
|
||||
|
||||
free(response);
|
||||
|
||||
return 1;
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
int check_dhcp(const struct arguments *args, const struct udp_session *u,
|
||||
const uint8_t *data, const size_t datalen) {
|
||||
|
||||
// This is untested
|
||||
// Android routing of DHCP is erroneous
|
||||
|
||||
log_android(ANDROID_LOG_WARN, "DHCP check");
|
||||
|
||||
if (datalen < sizeof(struct dhcp_packet)) {
|
||||
log_android(ANDROID_LOG_WARN, "DHCP packet size %d", datalen);
|
||||
return -1;
|
||||
}
|
||||
|
||||
const struct dhcp_packet *request = (struct dhcp_packet *) data;
|
||||
|
||||
if (ntohl(request->option_format) != DHCP_OPTION_MAGIC_NUMBER) {
|
||||
log_android(ANDROID_LOG_WARN, "DHCP invalid magic %x", request->option_format);
|
||||
return -1;
|
||||
}
|
||||
|
||||
if (request->htype != 1 || request->hlen != 6) {
|
||||
log_android(ANDROID_LOG_WARN, "DHCP unknown hardware htype %d hlen %d",
|
||||
request->htype, request->hlen);
|
||||
return -1;
|
||||
}
|
||||
|
||||
log_android(ANDROID_LOG_WARN, "DHCP opcode", request->opcode);
|
||||
|
||||
// Discover: source 0.0.0.0:68 destination 255.255.255.255:67
|
||||
// Offer: source 10.1.10.1:67 destination 255.255.255.255:68
|
||||
// Request: source 0.0.0.0:68 destination 255.255.255.255:67
|
||||
// Ack: source: 10.1.10.1 destination: 255.255.255.255
|
||||
|
||||
if (request->opcode == 1) { // Discover/request
|
||||
struct dhcp_packet *response = calloc(500, 1);
|
||||
|
||||
// Hack
|
||||
inet_pton(AF_INET, "10.1.10.1", &u->saddr);
|
||||
|
||||
/*
|
||||
Discover:
|
||||
DHCP option 53: DHCP Discover
|
||||
DHCP option 50: 192.168.1.100 requested
|
||||
DHCP option 55: Parameter Request List:
|
||||
Request Subnet Mask (1), Router (3), Domain Name (15), Domain Name Server (6)
|
||||
|
||||
Request
|
||||
DHCP option 53: DHCP Request
|
||||
DHCP option 50: 192.168.1.100 requested
|
||||
DHCP option 54: 192.168.1.1 DHCP server.
|
||||
*/
|
||||
|
||||
memcpy(response, request, sizeof(struct dhcp_packet));
|
||||
response->opcode = (uint8_t) (request->siaddr == 0 ? 2 /* Offer */ : /* Ack */ 4);
|
||||
response->secs = 0;
|
||||
response->flags = 0;
|
||||
memset(&response->ciaddr, 0, sizeof(response->ciaddr));
|
||||
inet_pton(AF_INET, "10.1.10.2", &response->yiaddr);
|
||||
inet_pton(AF_INET, "10.1.10.1", &response->siaddr);
|
||||
memset(&response->giaddr, 0, sizeof(response->giaddr));
|
||||
|
||||
// https://tools.ietf.org/html/rfc2132
|
||||
uint8_t *options = (uint8_t *) (response + sizeof(struct dhcp_packet));
|
||||
|
||||
int idx = 0;
|
||||
*(options + idx++) = 53; // Message type
|
||||
*(options + idx++) = 1;
|
||||
*(options + idx++) = (uint8_t) (request->siaddr == 0 ? 2 : 5);
|
||||
/*
|
||||
1 DHCPDISCOVER
|
||||
2 DHCPOFFER
|
||||
3 DHCPREQUEST
|
||||
4 DHCPDECLINE
|
||||
5 DHCPACK
|
||||
6 DHCPNAK
|
||||
7 DHCPRELEASE
|
||||
8 DHCPINFORM
|
||||
*/
|
||||
|
||||
*(options + idx++) = 1; // subnet mask
|
||||
*(options + idx++) = 4; // IP4 length
|
||||
inet_pton(AF_INET, "255.255.255.0", options + idx);
|
||||
idx += 4;
|
||||
|
||||
*(options + idx++) = 3; // gateway
|
||||
*(options + idx++) = 4; // IP4 length
|
||||
inet_pton(AF_INET, "10.1.10.1", options + idx);
|
||||
idx += 4;
|
||||
|
||||
*(options + idx++) = 51; // lease time
|
||||
*(options + idx++) = 4; // quad
|
||||
*((uint32_t *) (options + idx)) = 3600;
|
||||
idx += 4;
|
||||
|
||||
*(options + idx++) = 54; // DHCP
|
||||
*(options + idx++) = 4; // IP4 length
|
||||
inet_pton(AF_INET, "10.1.10.1", options + idx);
|
||||
idx += 4;
|
||||
|
||||
*(options + idx++) = 6; // DNS
|
||||
*(options + idx++) = 4; // IP4 length
|
||||
inet_pton(AF_INET, "8.8.8.8", options + idx);
|
||||
idx += 4;
|
||||
|
||||
*(options + idx++) = 255; // End
|
||||
|
||||
/*
|
||||
DHCP option 53: DHCP Offer
|
||||
DHCP option 1: 255.255.255.0 subnet mask
|
||||
DHCP option 3: 192.168.1.1 router
|
||||
DHCP option 51: 86400s (1 day) IP address lease time
|
||||
DHCP option 54: 192.168.1.1 DHCP server
|
||||
DHCP option 6: DNS servers 9.7.10.15
|
||||
*/
|
||||
|
||||
write_udp(args, u, (uint8_t *) response, 500);
|
||||
|
||||
free(response);
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
int open_udp_socket(const struct arguments *args, const struct udp_session *cur) {
|
||||
int sock;
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue