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Look up external IP via DNS instead of HTTP
Use myip.opendns.com via their resolver. The code is now TCP free again :)
This commit is contained in:
parent
e8a4c66719
commit
2032b44949
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@ -13,11 +13,11 @@ master:
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- README converted to markdown by Nicolas Braud-Santoni.
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- Linux: use pkg-config for systemd support flags.
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Patch by Jason A. Donenfeld.
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- Change external IP webservice to ipify.org
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- Add support for IPv6 in the server.
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Raw mode will be with same protocol as used for login.
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Traffic inside tunnel is still IPv4.
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- Update android build to support 5.0 (Lollipop) and newer.
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- Change external IP lookup to using myip.opendns.com via DNS.
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2014-06-16: 0.7.0 "Kryoptonite"
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- Partial IPv6 support (#107)
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@ -286,7 +286,7 @@ You must make sure the dns requests are forwarded to this port yourself.
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.B -n auto|external_ip
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The IP address to return in NS responses. Default is to return the address used
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as destination in the query.
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If external_ip is 'auto', iodined will use ipify.org web service to
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If external_ip is 'auto', iodined will use the opendns.com DNS service to
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retrieve the external IP of the host and use that for NS responses.
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.TP
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.B -b dnsport
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27
src/dns.c
27
src/dns.c
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@ -492,12 +492,27 @@ int dns_decode(char *buf, size_t buflen, struct query *q, qr_t qr, char *packet,
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readlong(packet, &data, &ttl);
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readshort(packet, &data, &rlen);
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memset(name, 0, sizeof(name));
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readname(packet, packetlen, &data, name, sizeof(name) - 1);
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name[sizeof(name)-1] = '\0';
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strncpy(buf, name, buflen);
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buf[buflen - 1] = '\0';
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rv = strlen(buf);
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if (type == T_CNAME) {
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/* For tunnels, query type A has CNAME type answer */
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memset(name, 0, sizeof(name));
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readname(packet, packetlen, &data, name, sizeof(name) - 1);
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name[sizeof(name)-1] = '\0';
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strncpy(buf, name, buflen);
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buf[buflen - 1] = '\0';
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rv = strlen(buf);
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}
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if (type == T_A) {
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/* Answer type A includes only 4 bytes.
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Not used for tunneling. */
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rv = MIN(rlen, sizeof(rdata));
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rv = readdata(packet, &data, rdata, rv);
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if (rv >= 2 && buf) {
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rv = MIN(rv, buflen);
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memcpy(buf, rdata, rv);
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} else {
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rv = 0;
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}
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}
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}
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else if ((type == T_MX || type == T_SRV) && buf) {
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/* We support 250 records, 250*(255+header) ~= 64kB.
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@ -123,57 +123,57 @@ get_dns_fd(struct dnsfd *fds, struct sockaddr_storage *addr)
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return fds->v4fd;
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}
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/* Ask ipify.org webservice to get external ip */
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/* Ask opendns.com DNS service for external ip */
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static int
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get_external_ip(struct in_addr *ip)
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{
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int sock;
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struct addrinfo *addr;
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static const char target[] = "myip.opendns.com";
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struct query query;
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int attempt;
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int res;
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const char *getstr = "GET / HTTP/1.0\r\n"
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/* HTTP 1.0 to avoid chunked transfer coding */
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"Host: api.ipify.org\r\n\r\n";
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char buf[512];
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char *b;
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int len;
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int fd;
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int out_len = 0;
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memset(&query, 0, sizeof(query));
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res = getaddrinfo("api.ipify.org", "80", NULL, &addr);
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query.type = T_A;
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res = get_addr("resolver1.opendns.com", 53, AF_INET, 0, &query.destination);
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if (res < 0) return 1;
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query.dest_len = res;
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sock = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
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if (sock < 0) {
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freeaddrinfo(addr);
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return 2;
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fd = open_dns_from_host(NULL, 0, AF_INET, AI_PASSIVE);
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if (fd < 0) return 2;
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for (attempt = 0; attempt < 3; attempt++) {
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char buf[64*1024];
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int buflen;
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fd_set fds;
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struct timeval tv;
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if (attempt) fprintf(stderr, "Retrying external IP lookup\n");
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query.id = rand();
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buflen = sizeof(buf);
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buflen = dns_encode(buf, buflen, &query, QR_QUERY, target, strlen(target));
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if (buflen < 0) continue;
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sendto(fd, buf, buflen, 0, (struct sockaddr*)&query.destination, query.dest_len);
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tv.tv_sec = 1 + attempt;
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tv.tv_usec = 0;
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FD_ZERO(&fds);
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FD_SET(fd, &fds);
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res = select(fd + 1, &fds, NULL, NULL, &tv);
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if (res > 0) {
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buflen = sizeof(buf);
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buflen = recv(fd, buf, buflen, 0);
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if (buflen > 0) {
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out_len = dns_decode((char *)ip, sizeof(struct in_addr), &query, QR_ANSWER, buf, buflen);
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if (out_len > 0) break;
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}
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}
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}
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res = connect(sock, addr->ai_addr, addr->ai_addrlen);
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freeaddrinfo(addr);
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if (res < 0) return 3;
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res = write(sock, getstr, strlen(getstr));
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if (res != strlen(getstr)) return 4;
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/* Zero buf before receiving, leave at least one zero at the end */
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memset(buf, 0, sizeof(buf));
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res = read(sock, buf, sizeof(buf) - 1);
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if (res < 0) return 5;
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len = res;
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res = close(sock);
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if (res < 0) return 6;
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b = buf;
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while (len > 9) {
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/* Look for split between headers and data */
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if (strncmp("\r\n\r\n", b, 4) == 0) break;
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b++;
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len--;
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}
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if (len < 10) return 7;
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b += 4;
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res = inet_aton(b, ip);
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return (res == 0);
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close_dns(fd);
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return (out_len != sizeof(struct in_addr));
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}
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static void
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@ -2616,7 +2616,7 @@ main(int argc, char **argv)
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struct in_addr extip;
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int res = get_external_ip(&extip);
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if (res) {
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fprintf(stderr, "Failed to get external IP via web service.\n");
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fprintf(stderr, "Failed to get external IP via DNS query.\n");
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exit(3);
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}
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ns_ip = extip.s_addr;
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