update server code #75

This commit is contained in:
J. A. Bezemer 2009-09-20 15:11:16 +00:00 committed by Erik Ekman
parent 55cfed9956
commit 40167437d3

View File

@ -68,6 +68,7 @@ static int running = 1;
static char *topdomain;
static char password[33];
static struct encoder *b32;
static struct encoder *b64;
static int created_users;
static int check_ip;
@ -85,7 +86,7 @@ static char *__progname;
#endif
static int read_dns(int, int, struct query *);
static void write_dns(int, struct query *, char *, int);
static void write_dns(int, struct query *, char *, int, char);
static void handle_full_packet(int, int);
static void
@ -119,7 +120,7 @@ check_user_and_ip(int userid, struct query *q)
if (userid < 0 || userid >= created_users ) {
return 1;
}
if (!users[userid].active) {
if (!users[userid].active || users[userid].disabled) {
return 1;
}
if (users[userid].last_pkt + 60 < time(NULL)) {
@ -225,7 +226,7 @@ send_version_response(int fd, version_ack_t ack, uint32_t payload, int userid, s
out[7] = ((payload) & 0xff);
out[8] = userid & 0xff;
write_dns(fd, q, out, sizeof(out));
write_dns(fd, q, out, sizeof(out), users[userid].downenc);
}
static void
@ -270,7 +271,7 @@ send_chunk(int dns_fd, int userid) {
users[userid].outpacket.seqno & 7, users[userid].outpacket.fragment & 15,
last, users[userid].outpacket.offset, datalen, users[userid].outpacket.len, userid);
}
write_dns(dns_fd, &users[userid].q, pkt, datalen + 2);
write_dns(dns_fd, &users[userid].q, pkt, datalen + 2, users[userid].downenc);
users[userid].q.id = 0;
if (users[userid].outpacket.len > 0 &&
@ -360,10 +361,21 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
memcpy(&(users[userid].q), q, sizeof(struct query));
users[userid].encoder = get_base32_encoder();
users[userid].downenc = 'T';
send_version_response(dns_fd, VERSION_ACK, users[userid].seed, userid, q);
syslog(LOG_INFO, "accepted version for user #%d from %s",
userid, inet_ntoa(tempin->sin_addr));
users[userid].q.id = 0;
users[userid].outpacket.len = 0;
users[userid].outpacket.offset = 0;
users[userid].outpacket.sentlen = 0;
users[userid].outpacket.seqno = 0;
users[userid].outpacket.fragment = 0;
users[userid].inpacket.len = 0;
users[userid].inpacket.offset = 0;
users[userid].inpacket.seqno = 0;
users[userid].inpacket.fragment = 0;
users[userid].fragsize = 100; /* very safe */
} else {
/* No space for another user */
send_version_response(dns_fd, VERSION_FULL, created_users, 0, q);
@ -382,7 +394,7 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
userid = unpacked[0];
if (check_user_and_ip(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
write_dns(dns_fd, q, "BADIP", 5, 'T');
syslog(LOG_WARNING, "dropped login request from user #%d from unexpected source %s",
userid, inet_ntoa(((struct sockaddr_in *) &q->from)->sin_addr));
return;
@ -401,14 +413,14 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
read = snprintf(out, sizeof(out), "%s-%s-%d-%d",
tmp[0], tmp[1], my_mtu, netmask);
write_dns(dns_fd, q, out, read);
write_dns(dns_fd, q, out, read, users[userid].downenc);
q->id = 0;
syslog(LOG_NOTICE, "accepted password from user #%d, given IP %s", userid, tmp[1]);
free(tmp[1]);
free(tmp[0]);
} else {
write_dns(dns_fd, q, "LNAK", 4);
write_dns(dns_fd, q, "LNAK", 4, 'T');
syslog(LOG_WARNING, "rejected login request from user #%d from %s, bad password",
userid, inet_ntoa(((struct sockaddr_in *) &q->from)->sin_addr));
}
@ -422,7 +434,7 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
userid = b32_8to5(in[1]);
if (check_user_and_ip(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
write_dns(dns_fd, q, "BADIP", 5, 'T');
return; /* illegal id */
}
@ -440,25 +452,26 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
reply[2] = (addr >> 16) & 0xFF;
reply[3] = (addr >> 8) & 0xFF;
reply[4] = (addr >> 0) & 0xFF;
write_dns(dns_fd, q, reply, sizeof(reply));
write_dns(dns_fd, q, reply, sizeof(reply), 'T');
} else if(in[0] == 'Z' || in[0] == 'z') {
/* Check for case conservation and chars not allowed according to RFC */
/* Reply with received hostname as data */
write_dns(dns_fd, q, in, domain_len);
/* No userid here, reply with lowest-grade downenc */
write_dns(dns_fd, q, in, domain_len, 'T');
return;
} else if(in[0] == 'S' || in[0] == 's') {
int codec;
struct encoder *enc;
if (domain_len < 3) { /* len at least 3, example: "S15" */
write_dns(dns_fd, q, "BADLEN", 6);
write_dns(dns_fd, q, "BADLEN", 6, 'T');
return;
}
userid = b32_8to5(in[1]);
if (check_user_and_ip(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
write_dns(dns_fd, q, "BADIP", 5, 'T');
return; /* illegal id */
}
@ -468,15 +481,49 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
case 5: /* 5 bits per byte = base32 */
enc = get_base32_encoder();
user_switch_codec(userid, enc);
write_dns(dns_fd, q, enc->name, strlen(enc->name));
write_dns(dns_fd, q, enc->name, strlen(enc->name), users[userid].downenc);
break;
case 6: /* 6 bits per byte = base64 */
enc = get_base64_encoder();
user_switch_codec(userid, enc);
write_dns(dns_fd, q, enc->name, strlen(enc->name));
write_dns(dns_fd, q, enc->name, strlen(enc->name), users[userid].downenc);
break;
default:
write_dns(dns_fd, q, "BADCODEC", 8);
write_dns(dns_fd, q, "BADCODEC", 8, users[userid].downenc);
break;
}
return;
} else if(in[0] == 'O' || in[0] == 'o') {
if (domain_len != 4) { /* len = 4, example: "O1T." */
write_dns(dns_fd, q, "BADLEN", 6, 'T');
return;
}
userid = b32_8to5(in[1]);
if (check_user_and_ip(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5, 'T');
return; /* illegal id */
}
switch (in[2]) {
case 'T':
case 't':
users[userid].downenc = 'T';
write_dns(dns_fd, q, "Base32", 6, users[userid].downenc);
break;
case 'S':
case 's':
users[userid].downenc = 'S';
write_dns(dns_fd, q, "Base64", 6, users[userid].downenc);
break;
case 'R':
case 'r':
users[userid].downenc = 'R';
write_dns(dns_fd, q, "Raw", 3, users[userid].downenc);
break;
default:
write_dns(dns_fd, q, "BADCODEC", 8, users[userid].downenc);
break;
}
return;
@ -486,20 +533,26 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
/* Downstream fragsize probe packet */
userid = (b32_8to5(in[1]) >> 1) & 15;
if (check_user_and_ip(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
write_dns(dns_fd, q, "BADIP", 5, 'T');
return; /* illegal id */
}
req_frag_size = ((b32_8to5(in[1]) & 1) << 10) | ((b32_8to5(in[2]) & 31) << 5) | (b32_8to5(in[3]) & 31);
if (req_frag_size < 2 || req_frag_size > 2047) {
write_dns(dns_fd, q, "BADFRAG", 7);
write_dns(dns_fd, q, "BADFRAG", 7, users[userid].downenc);
} else {
char buf[2048];
int i;
unsigned int v = (unsigned int) rand();
memset(buf, 0, sizeof(buf));
buf[0] = (req_frag_size >> 8) & 0xff;
buf[1] = req_frag_size & 0xff;
write_dns(dns_fd, q, buf, req_frag_size);
/* make checkable pseudo-random sequence */
buf[2] = 107;
for (i = 3; i < 2048; i++, v += 107)
buf[i] = (char) (v & 0xff);
write_dns(dns_fd, q, buf, req_frag_size, users[userid].downenc);
}
return;
} else if(in[0] == 'N' || in[0] == 'n') {
@ -509,16 +562,16 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
/* Downstream fragsize packet */
userid = unpacked[0];
if (check_user_and_ip(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
write_dns(dns_fd, q, "BADIP", 5, 'T');
return; /* illegal id */
}
max_frag_size = ((unpacked[1] & 0xff) << 8) | (unpacked[2] & 0xff);
if (max_frag_size < 2) {
write_dns(dns_fd, q, "BADFRAG", 7);
write_dns(dns_fd, q, "BADFRAG", 7, users[userid].downenc);
} else {
users[userid].fragsize = max_frag_size;
write_dns(dns_fd, q, &unpacked[1], 2);
write_dns(dns_fd, q, &unpacked[1], 2, users[userid].downenc);
}
return;
} else if(in[0] == 'P' || in[0] == 'p') {
@ -529,7 +582,7 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
/* Ping packet, store userid */
userid = unpacked[0];
if (check_user_and_ip(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
write_dns(dns_fd, q, "BADIP", 5, 'T');
return; /* illegal id */
}
@ -564,7 +617,7 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
userid = code;
/* Check user and sending ip number */
if (check_user_and_ip(userid, q) != 0) {
write_dns(dns_fd, q, "BADIP", 5);
write_dns(dns_fd, q, "BADIP", 5, 'T');
} else {
/* Decode data header */
int up_seq = (b32_8to5(in[1]) >> 2) & 7;
@ -637,6 +690,10 @@ handle_ns_request(int dns_fd, struct query *q)
}
len = dns_encode_ns_response(buf, sizeof(buf), q, topdomain);
if (len < 1) {
warnx("dns_encode_ns_response doesn't fit");
return;
}
if (debug >= 2) {
struct sockaddr_in *tempin;
@ -659,6 +716,10 @@ forward_query(int bind_fd, struct query *q)
in_addr_t newaddr;
len = dns_encode(buf, sizeof(buf), q, QR_QUERY, q->name, strlen(q->name));
if (len < 1) {
warnx("dns_encode doesn't fit");
return;
}
/* Store sockaddr for q->id */
memcpy(&(fwq.addr), &(q->from), q->fromlen);
@ -755,8 +816,14 @@ tunnel_dns(int tun_fd, int dns_fd, int bind_fd)
if (inside_topdomain) {
/* This is a query we can handle */
switch (q.type) {
case T_NULL:
case T_CNAME:
case T_A:
case T_MX:
case T_TXT:
/* encoding is "transparent" here */
handle_null_request(tun_fd, dns_fd, &q, domain_len);
break;
case T_NS:
@ -1044,12 +1111,91 @@ read_dns(int fd, int tun_fd, struct query *q) /* FIXME: tun_fd is because of raw
}
static void
write_dns(int fd, struct query *q, char *data, int datalen)
write_dns(int fd, struct query *q, char *data, int datalen, char downenc)
{
char buf[64*1024];
int len;
int len = 0;
len = dns_encode(buf, sizeof(buf), q, QR_ANSWER, data, datalen);
if (q->type == T_CNAME || q->type == T_A || q->type == T_MX) {
static int td1 = 0;
static int td2 = 0;
char cnamebuf[1024]; /* max 255 */
size_t space;
char *b;
/* Make a rotating topdomain to prevent filtering */
td1+=3;
td2+=7;
if (td1>=26) td1-=26;
if (td2>=25) td2-=25;
/* encode data,datalen to CNAME/MX answer */
/* (adapted from build_hostname() in iodine.c) */
space = MIN(0xFF, sizeof(cnamebuf)) - 4 - 2;
/* -1 encoding type, -3 ".xy", -2 for safety */
memset(cnamebuf, 0, sizeof(cnamebuf));
if (downenc == 'S') {
cnamebuf[0] = 'I';
if (!b64->places_dots())
space -= (space / 57); /* space for dots */
b64->encode(cnamebuf+1, &space, data, datalen);
if (!b64->places_dots())
inline_dotify(cnamebuf, sizeof(cnamebuf), 57);
} else {
cnamebuf[0] = 'H';
if (!b32->places_dots())
space -= (space / 57); /* space for dots */
b32->encode(cnamebuf+1, &space, data, datalen);
if (!b32->places_dots())
inline_dotify(cnamebuf, sizeof(cnamebuf), 57);
}
/* Add dot (if it wasn't there already) and topdomain */
b = cnamebuf;
b += strlen(cnamebuf);
if (*b != '.')
*b++ = '.';
*b = 'a' + td1;
b++;
*b = 'a' + td2;
b++;
*b = '\0';
len = dns_encode(buf, sizeof(buf), q, QR_ANSWER, cnamebuf, sizeof(cnamebuf));
}
else if (q->type == T_TXT) {
/* TXT with base32 */
char txtbuf[64*1024];
size_t space = sizeof(txtbuf) - 1;;
memset(txtbuf, 0, sizeof(txtbuf));
if (downenc == 'S') {
txtbuf[0] = 'S'; /* plain base64(Sixty-four) */
len = b64->encode(txtbuf+1, &space, data, datalen);
}
else if (downenc == 'R') {
txtbuf[0] = 'R'; /* Raw binary data */
len = MIN(datalen, sizeof(txtbuf) - 1);
memcpy(txtbuf + 1, data, len);
} else {
txtbuf[0] = 'T'; /* plain base32(Thirty-two) */
len = b32->encode(txtbuf+1, &space, data, datalen);
}
len = dns_encode(buf, sizeof(buf), q, QR_ANSWER, txtbuf, len+1);
} else {
/* Normal NULL-record encode */
len = dns_encode(buf, sizeof(buf), q, QR_ANSWER, data, datalen);
}
if (len < 1) {
warnx("dns_encode doesn't fit");
return;
}
if (debug >= 2) {
struct sockaddr_in *tempin;
@ -1166,6 +1312,7 @@ main(int argc, char **argv)
pidfile = NULL;
b32 = get_base32_encoder();
b64 = get_base64_encoder();
retval = 0;