From eee8db5cf32e62d4842355ac9d77d756416696d9 Mon Sep 17 00:00:00 2001 From: Sergey Matveev Date: Thu, 10 Nov 2022 17:11:19 +0300 Subject: [PATCH] Debug with IP addresses --- CHANGES | 1 + dht-bootstrap.c | 1696 +++++++++++++++++++++++------------------------ 2 files changed, 828 insertions(+), 869 deletions(-) diff --git a/CHANGES b/CHANGES index 69f5564..e8a770d 100644 --- a/CHANGES +++ b/CHANGES @@ -5,6 +5,7 @@ * arc4random instead of /dev/urandom reading * Some simple hardening * Keep statistics in process title (BSD) + * Debug with IP addresses 20 November 2011: dht-bootstrap-0.2 diff --git a/dht-bootstrap.c b/dht-bootstrap.c index 07ac332..2627d82 100644 --- a/dht-bootstrap.c +++ b/dht-bootstrap.c @@ -26,7 +26,6 @@ THE SOFTWARE. #include #include #include -#include #include #include #include @@ -37,51 +36,6 @@ THE SOFTWARE. #define MIN(x, y) ((x) <= (y) ? (x) : (y)) -#ifdef __linux__ -// clang-format off -void setproctitle_fast(const char *_fmt, ...) {} -// clang-format on -#endif - -static int -send_ping(struct sockaddr *sa, int salen, const unsigned char *tid, int tid_len); -static int -send_pong(struct sockaddr *sa, int salen, const unsigned char *tid, int tid_len); -static int -send_find_node( - struct sockaddr *sa, - int salen, - const unsigned char *tid, - int tid_len, - const unsigned char *target, - int want); -static int -send_nodes( - struct sockaddr *sa, - int salen, - const unsigned char *tid, - int tid_len, - const unsigned char *nodes, - int nodes_len, - const unsigned char *nodes6, - int nodes6_len); -static int -send_random_nodes( - struct sockaddr *sa, - int salen, - const unsigned char *tid, - int tid_len, - const unsigned char *id, - int want); -static int -send_error( - struct sockaddr *sa, - int salen, - unsigned char *tid, - int tid_len, - int code, - const char *message); - #define ERROR 0 #define REPLY 1 #define PING 2 @@ -92,34 +46,11 @@ send_error( #define WANT4 1 #define WANT6 2 -static int -parse_message( - const unsigned char *buf, - int buflen, - unsigned char *tid_return, - int *tid_len, - unsigned char *id_return, - unsigned char *info_hash_return, - unsigned char *target_return, - unsigned short *port_return, - unsigned char *token_return, - int *token_len, - unsigned char *nodes_return, - int *nodes_len, - unsigned char *nodes6_return, - int *nodes6_len, - unsigned char *values_return, - int *values_len, - unsigned char *values6_return, - int *values6_len, - int *want_return); - static const unsigned char zeroes[20] = {0}; static const unsigned char v4prefix[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF, 0, 0, 0, 0}; static unsigned char myid[20]; -static int have_v = 0; static unsigned char my_v[9]; static int dht_socket = -1; @@ -145,618 +76,482 @@ static struct circular_list v4_new, v6_new, v4_confirmed, v6_confirmed; static time_t token_bucket_time; static int token_bucket_tokens; -static FILE *dht_debug = NULL; +static int verbose = 1; -static void -debugf(const char *format, ...) -{ - if (dht_debug == NULL) - return; - va_list args; - va_start(args, format); - vfprintf(dht_debug, format, args); - va_end(args); - fflush(dht_debug); -} +// ------------------------ >8 ------------------------ -static int -is_martian(struct sockaddr *sa) +static const char * +getAddr(const struct sockaddr *sa, const size_t saLen) { - switch (sa->sa_family) { - case AF_INET: { - struct sockaddr_in *sin = (struct sockaddr_in *)sa; - const unsigned char *address = (const unsigned char *)&sin->sin_addr; - return sin->sin_port == 0 || (address[0] == 0) || (address[0] == 127) || - ((address[0] & 0xE0) == 0xE0); - } - case AF_INET6: { - struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa; - const unsigned char *address = (const unsigned char *)&sin6->sin6_addr; - return sin6->sin6_port == 0 || (address[0] == 0xFF) || - (address[0] == 0xFE && (address[1] & 0xC0) == 0x80) || - (memcmp(address, zeroes, 15) == 0 && - (address[15] == 0 || address[15] == 1)) || - (memcmp(address, v4prefix, 12) == 0); - } - - default: - return 0; + static char host[NI_MAXHOST]; + static char port[NI_MAXSERV]; + static char addr[64]; + int rc = getnameinfo( + sa, + saLen, + host, + sizeof host, + port, + sizeof port, + NI_NUMERICHOST | NI_NUMERICSERV); + if (rc != 0) { + fprintf(stderr, "getnameinfo: %s\n", gai_strerror(rc)); + return NULL; } + snprintf(addr, sizeof addr, "[%s]:%s", host, port); + return addr; } -/* Forget about the ``XOR-metric''. An id is just a path from the - root of the tree, so bits are numbered from the start. */ - -static inline int -id_cmp(const unsigned char *restrict id1, const unsigned char *restrict id2) -{ - /* Memcmp is guaranteed to perform an unsigned comparison. */ - return memcmp(id1, id2, 20); -} - -/* Our transaction-ids are 4-bytes long, with the first two bytes identi- - fying the kind of request, and the remaining two a sequence number in - host order. */ - -static void -make_tid(unsigned char *tid_return, const char *prefix, unsigned short seqno) -{ - tid_return[0] = prefix[0] & 0xFF; - tid_return[1] = prefix[1] & 0xFF; - memcpy(tid_return + 2, &seqno, 2); -} - -static int -tid_match(const unsigned char *tid, const char *prefix, unsigned short *seqno_return) -{ - if (tid[0] == (prefix[0] & 0xFF) && tid[1] == (prefix[1] & 0xFF)) { - if (seqno_return) - memcpy(seqno_return, tid + 2, 2); - return 1; - } else - return 0; -} - -static inline int -circular(int from, int to) -{ - int x = to - from; - if (x < 0) - return x + CIRCULAR_LIST_SIZE; - return x; -} - -static int -list_elements(struct circular_list *list) -{ - return circular(list->head, list->tail); -} - -static int -list_empty(struct circular_list *list) -{ - return list_elements(list) == 0; -} - -static int -list_free(struct circular_list *list) -{ - return circular(list->tail + 1, list->head); -} - -static int -list_pop(struct circular_list *list, struct sockaddr_storage *ss, socklen_t *sslen) -{ - if (list->head == list->tail) - return 0; - - memcpy(ss, &list->nodes[list->head].ss, list->nodes[list->head].sslen); - *sslen = list->nodes[list->head].sslen; - list->head = (list->head + 1) % CIRCULAR_LIST_SIZE; - return 1; -} - -static int -list_random( - struct circular_list *list, - unsigned char *id, - struct sockaddr_storage *ss, - socklen_t *sslen) -{ - int n; - if (list->head == list->tail) - return 0; - - n = random() % (list->tail - list->head); - n = (list->head + n) % CIRCULAR_LIST_SIZE; - - if (id) - memcpy(id, &list->nodes[n].id, 20); - memcpy(ss, &list->nodes[n].ss, list->nodes[n].sslen); - *sslen = list->nodes[n].sslen; - return 1; -} - -/* We just learnt about a node, not necessarily a new one. Confirm is 1 if - the node sent a message, 2 if it sent us a reply. */ - static int -new_node(unsigned char *id, struct sockaddr *sa, socklen_t salen, int confirm) +parse_message( + const unsigned char *buf, + int buflen, + unsigned char *tid_return, + int *tid_len, + unsigned char *id_return, + unsigned char *info_hash_return, + unsigned char *target_return, + unsigned short *port_return, + unsigned char *token_return, + int *token_len, + unsigned char *nodes_return, + int *nodes_len, + unsigned char *nodes6_return, + int *nodes6_len, + unsigned char *values_return, + int *values_len, + unsigned char *values6_return, + int *values6_len, + int *want_return, + const struct sockaddr *sa, + const size_t saLen) { - struct circular_list *list; - int i; - - if (sa->sa_family == AF_INET) - list = confirm >= 2 ? &v4_confirmed : &v4_new; - else if (sa->sa_family == AF_INET6) - list = confirm >= 2 ? &v6_confirmed : &v6_new; - else - abort(); - - /* A node that sends us a request is most probably bootstrapping. - We want to avoid getting our tables full of very young nodes -- only - include such a node if we have plenty of space. */ - - if (confirm == 1 && list_free(list) < 32) - return 0; + const unsigned char *p; - for (i = list->head; i != list->tail; i = (i + 1) % CIRCULAR_LIST_SIZE) { - struct node *n = &list->nodes[i]; - if (n->sslen == salen && memcmp(&n->ss, sa, salen) == 0) - return 0; + /* This code will happily crash if the buffer is not NUL-terminated. */ + if (buf[buflen] != '\0') { + if (verbose) + printf("%s : parse_message with unterminated buffer\n", getAddr(sa, saLen)); + return -1; } - memcpy(&list->nodes[list->tail].id, id, 160); - memcpy(&list->nodes[list->tail].ss, sa, salen); - list->nodes[list->tail].sslen = salen; - list->tail = (list->tail + 1) % CIRCULAR_LIST_SIZE; - if (list->head == list->tail) - list->head = (list->head + 1) % CIRCULAR_LIST_SIZE; - - return 1; -} +#define CHECK(ptr, len) \ + if (((unsigned char *)ptr) + (len) > (buf) + (buflen)) \ + goto overflow; -static int -token_bucket(void) -{ - time_t now = time(NULL); - if (token_bucket_tokens == 0) { - token_bucket_tokens = - MIN(MAX_TOKEN_BUCKET_TOKENS, 4 * (now - token_bucket_time)); - token_bucket_time = now; + if (tid_return) { + p = memmem(buf, buflen, "1:t", 3); + if (p) { + long l; + char *q; + l = strtol((char *)p + 3, &q, 10); + if (q && *q == ':' && l > 0 && l < *tid_len) { + CHECK(q + 1, l); + memcpy(tid_return, q + 1, l); + *tid_len = l; + } else + *tid_len = 0; + } } - - if (token_bucket_tokens == 0) - return 0; - - token_bucket_tokens--; - return 1; -} - -static int -send_request(struct circular_list *list, int dopop, int doping, int want) -{ - unsigned char ttid[4]; - struct sockaddr_storage ss; - socklen_t sslen; - int rc; - - if (list_empty(list)) - return 0; - - if (dopop) { - rc = list_pop(list, &ss, &sslen); - if (rc == 0) - return 0; - } else { - rc = list_random(list, NULL, &ss, &sslen); - if (rc == 0) - return 0; + if (id_return) { + p = memmem(buf, buflen, "2:id20:", 7); + if (p) { + CHECK(p + 7, 20); + memcpy(id_return, p + 7, 20); + } else { + memset(id_return, 0, 20); + } } - - if (doping) { - make_tid(ttid, "pn", 0); - debugf("Sending ping.\n"); - return send_ping((struct sockaddr *)&ss, sslen, ttid, 4); - } else { - unsigned char id[20]; - arc4random_buf(id, sizeof id); - make_tid(ttid, "fn", 0); - debugf("Sending find_node.\n"); - return send_find_node((struct sockaddr *)&ss, sslen, ttid, 4, id, want); + if (info_hash_return) { + p = memmem(buf, buflen, "9:info_hash20:", 14); + if (p) { + CHECK(p + 14, 20); + memcpy(info_hash_return, p + 14, 20); + } else { + memset(info_hash_return, 0, 20); + } } -} - -static int -newSock(const char *host, const char *port) -{ - struct addrinfo hints; - memset(&hints, 0, sizeof(hints)); - hints.ai_family = AF_UNSPEC; - hints.ai_socktype = SOCK_DGRAM; - struct addrinfo *res = NULL; - int rc = getaddrinfo(host, port, &hints, &res); - if (rc != 0) - err(EXIT_FAILURE, "getaddrinfo: %s\n", gai_strerror(rc)); - int sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol); - if (sock == -1) - err(EXIT_FAILURE, "socket()"); - if (bind(sock, res->ai_addr, res->ai_addrlen) != 0) - err(EXIT_FAILURE, "bind()"); - rc = fcntl(sock, F_GETFL, 0); - if (rc < 0) - err(EXIT_FAILURE, "F_GETFL"); - rc = fcntl(sock, F_SETFL, (rc | O_NONBLOCK)); - if (rc < 0) - err(EXIT_FAILURE, "F_SETFL"); - freeaddrinfo(res); - return sock; -} - -static void -rlimited(int res) -{ - struct rlimit r; - r.rlim_cur = 0; - r.rlim_max = 0; - if (setrlimit(res, &r) == -1) { - err(EXIT_FAILURE, "can not setrlimit()"); + if (port_return) { + p = memmem(buf, buflen, "porti", 5); + if (p) { + long l; + char *q; + l = strtol((char *)p + 5, &q, 10); + if (q && *q == 'e' && l > 0 && l < 0x10000) + *port_return = l; + else + *port_return = 0; + } else + *port_return = 0; } -} - -int -main(int argc, char **argv) -{ - errno = 0; - int quiet = 0; - char *ipv4addr = NULL; - char *ipv6addr = NULL; - int opt = 0; - - while (1) { - opt = getopt(argc, argv, "q4:6:"); - if (opt < 0) - break; - - switch (opt) { - case 'q': - quiet = 1; - break; - case '4': - ipv4addr = strdup(optarg); - break; - case '6': - ipv6addr = strdup(optarg); - break; - default: - goto usage; + if (target_return) { + p = memmem(buf, buflen, "6:target20:", 11); + if (p) { + CHECK(p + 11, 20); + memcpy(target_return, p + 11, 20); + } else { + memset(target_return, 0, 20); } } - - int i = optind; - - if (argc < i + 1) - goto usage; - - const char *ourPort = strdup(argv[i++]); - if (ipv4addr != NULL) { - dht_socket = newSock(ipv4addr, ourPort); - } - if (ipv6addr != NULL) { - dht_socket6 = newSock(ipv6addr, ourPort); + if (token_return) { + p = memmem(buf, buflen, "5:token", 7); + if (p) { + long l; + char *q; + l = strtol((char *)p + 7, &q, 10); + if (q && *q == ':' && l > 0 && l < *token_len) { + CHECK(q + 1, l); + memcpy(token_return, q + 1, l); + *token_len = l; + } else + *token_len = 0; + } else + *token_len = 0; } - arc4random_buf(myid, sizeof myid); - - memcpy(my_v, "1:v4:JB\0\0", 9); - have_v = 1; - - if (!quiet) - dht_debug = stdout; - - int rc = 0; - unsigned char ttid[4]; - - while (i < argc) { - struct addrinfo hints, *info, *infop; - memset(&hints, 0, sizeof(hints)); - hints.ai_socktype = SOCK_DGRAM; - hints.ai_family = 0; - if (dht_socket < 0) - hints.ai_family = AF_INET6; - else if (dht_socket6 < 0) - hints.ai_family |= AF_INET; - rc = getaddrinfo(argv[i], argv[i + 1], &hints, &info); - if (rc != 0) - err(EXIT_FAILURE, "getaddrinfo: %s\n", gai_strerror(rc)); + if (nodes_len) { + p = memmem(buf, buflen, "5:nodes", 7); + if (p) { + long l; + char *q; + l = strtol((char *)p + 7, &q, 10); + if (q && *q == ':' && l > 0 && l < *nodes_len) { + CHECK(q + 1, l); + memcpy(nodes_return, q + 1, l); + *nodes_len = l; + } else + *nodes_len = 0; + } else + *nodes_len = 0; + } - i++; - if (i >= argc) - goto usage; + if (nodes6_len) { + p = memmem(buf, buflen, "6:nodes6", 8); + if (p) { + long l; + char *q; + l = strtol((char *)p + 8, &q, 10); + if (q && *q == ':' && l > 0 && l < *nodes6_len) { + CHECK(q + 1, l); + memcpy(nodes6_return, q + 1, l); + *nodes6_len = l; + } else + *nodes6_len = 0; + } else + *nodes6_len = 0; + } - infop = info; - while (infop) { - make_tid(ttid, "pn", 0); - debugf("Sending ping.\n"); - send_ping(infop->ai_addr, infop->ai_addrlen, ttid, 4); - infop = infop->ai_next; + if (values_len || values6_len) { + p = memmem(buf, buflen, "6:valuesl", 9); + if (p) { + int i = p - buf + 9; + int j = 0, j6 = 0; + while (1) { + long l; + char *q; + l = strtol((char *)buf + i, &q, 10); + if (q && *q == ':' && l > 0) { + CHECK(q + 1, l); + if (l == 6) { + if (j + l > *values_len) + continue; + i = q + 1 + l - (char *)buf; + memcpy((char *)values_return + j, q + 1, l); + j += l; + } else if (l == 18) { + if (j6 + l > *values6_len) + continue; + i = q + 1 + l - (char *)buf; + memcpy((char *)values6_return + j6, q + 1, l); + j6 += l; + } else { + if (verbose) + printf( + "%s : received weird value: %d bytes\n", + getAddr(sa, saLen), + (int)l); + i = q + 1 + l - (char *)buf; + } + } else { + break; + } + } + if (i >= buflen || buf[i] != 'e') + if (verbose) + printf("%s : unexpected end for values\n", getAddr(sa, saLen)); + if (values_len) + *values_len = j; + if (values6_len) + *values6_len = j6; + } else { + *values_len = 0; + *values6_len = 0; } - freeaddrinfo(info); + } - i++; + if (want_return) { + p = memmem(buf, buflen, "4:wantl", 7); + if (p) { + int i = p - buf + 7; + *want_return = 0; + while (buf[i] > '0' && buf[i] <= '9' && buf[i + 1] == ':' && + i + 2 + buf[i] - '0' < buflen) { + CHECK(buf + i + 2, buf[i] - '0'); + if (buf[i] == '2' && memcmp(buf + i + 2, "n4", 2) == 0) + *want_return |= WANT4; + else if (buf[i] == '2' && memcmp(buf + i + 2, "n6", 2) == 0) + *want_return |= WANT6; + else if (verbose) + printf( + "%s : unexpected want flag: %c\n", getAddr(sa, saLen), buf[i]); + i += 2 + buf[i] - '0'; + } + if (i >= buflen || buf[i] != 'e') + if (verbose) + printf("%s : unexpected end for want\n", getAddr(sa, saLen)); + } else { + *want_return = -1; + } } - token_bucket_time = time(NULL); - token_bucket_tokens = MAX_TOKEN_BUCKET_TOKENS; - int send4 = 0; - struct pollfd fds[2]; - fds[0].fd = dht_socket; - fds[0].events = POLLIN; - fds[1].fd = dht_socket6; - fds[1].events = POLLIN; +#undef CHECK - close(STDIN_FILENO); - if (quiet) - close(STDOUT_FILENO); - rlimited(RLIMIT_NPROC); - rlimited(RLIMIT_FSIZE); -#if __FreeBSD__ - rlimited(RLIMIT_NOFILE); -#endif // __FreeBSD__ + if (memmem(buf, buflen, "1:y1:r", 6)) + return REPLY; + if (memmem(buf, buflen, "1:y1:e", 6)) + return ERROR; + if (!memmem(buf, buflen, "1:y1:q", 6)) + return -1; + if (memmem(buf, buflen, "1:q4:ping", 9)) + return PING; + if (memmem(buf, buflen, "1:q9:find_node", 14)) + return FIND_NODE; + if (memmem(buf, buflen, "1:q9:get_peers", 14)) + return GET_PEERS; + if (memmem(buf, buflen, "1:q13:announce_peer", 19)) + return ANNOUNCE_PEER; + return -1; - while (1) { - int tv_sec = 0; - if ((dht_socket >= 0 && list_elements(&v4_confirmed) <= 16) || - (dht_socket6 >= 0 && list_elements(&v6_confirmed) <= 16)) - tv_sec = 0; - else - tv_sec = random() % 30; - int tv_msec = random() % 1000; +overflow: + if (verbose) + printf(": truncated message\n"); + return -1; +} - setproctitle_fast( - "%d+%d %d+%d", - list_elements(&v4_confirmed), - list_elements(&v6_confirmed), - list_elements(&v4_new), - list_elements(&v6_new)); +#undef CHECK +#undef INC +#undef COPY +#undef ADD_V - rc = poll(fds, 2, tv_sec * 1000 + tv_msec); - if (rc < 0) { - perror("poll"); - sleep(1); - } +/* We could use a proper bencoding printer and parser, but the format of + DHT messages is fairly stylised, so this seemed simpler. */ - if (rc > 0) { - int message; - unsigned char tid[16], id[20], info_hash[20], target[20]; - unsigned char buf[1536], nodes[256], nodes6[1024], token[128]; - int tid_len = 16, token_len = 128; - int nodes_len = 256, nodes6_len = 1024; - unsigned short port; - unsigned char values[2048], values6[2048]; - int values_len = 2048, values6_len = 2048; - int want; - struct sockaddr_storage source_storage; - struct sockaddr *source = (struct sockaddr *)&source_storage; - socklen_t sourcelen = sizeof(source_storage); - if (fds[0].revents != 0) { - if ((fds[0].revents & (POLLERR | POLLNVAL)) > 0) { - fprintf(stderr, "error in fds[0]"); - rc = -1; - } else { - rc = recvfrom(dht_socket, buf, 1536, 0, source, &sourcelen); - } - } else if (fds[1].revents != 0) { - if ((fds[1].revents & (POLLERR | POLLNVAL)) > 0) { - fprintf(stderr, "error in fds[1]"); - rc = -1; - } else { - rc = recvfrom(dht_socket6, buf, 1536, 0, source, &sourcelen); - } - } +#define CHECK(offset, delta, size) \ + if (delta < 0 || offset + delta > size) \ + goto fail - if (rc < 0 || sourcelen > sizeof(struct sockaddr_storage)) - goto dontread; +#define INC(offset, delta, size) \ + CHECK(offset, delta, size); \ + offset += delta - if (is_martian(source)) - goto dontread; +#define COPY(buf, offset, src, delta, size) \ + CHECK(offset, delta, size); \ + memcpy(buf + offset, src, delta); \ + offset += delta; - /* There's a bug in parse_message -- it will happily overflow the - buffer if it's not NUL-terminated. For now, put a NUL at the - end of buffers. */ +#define ADD_V(buf, offset, size) COPY(buf, offset, my_v, (sizeof my_v), size) - if (rc < 1536) { - buf[rc] = '\0'; - } else { - debugf("Overlong message.\n"); - goto dontread; - } +static int +is_martian(struct sockaddr *sa) +{ + switch (sa->sa_family) { + case AF_INET: { + struct sockaddr_in *sin = (struct sockaddr_in *)sa; + const unsigned char *address = (const unsigned char *)&sin->sin_addr; + return sin->sin_port == 0 || (address[0] == 0) || (address[0] == 127) || + ((address[0] & 0xE0) == 0xE0); + } + case AF_INET6: { + struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa; + const unsigned char *address = (const unsigned char *)&sin6->sin6_addr; + return sin6->sin6_port == 0 || (address[0] == 0xFF) || + (address[0] == 0xFE && (address[1] & 0xC0) == 0x80) || + (memcmp(address, zeroes, 15) == 0 && + (address[15] == 0 || address[15] == 1)) || + (memcmp(address, v4prefix, 12) == 0); + } - message = parse_message( - buf, - rc, - tid, - &tid_len, - id, - info_hash, - target, - &port, - token, - &token_len, - nodes, - &nodes_len, - nodes6, - &nodes6_len, - values, - &values_len, - values6, - &values6_len, - &want); + default: + return 0; + } +} - if (id_cmp(id, myid) == 0) { - debugf("Received message from self.\n"); - goto dontread; - } +/* Forget about the ``XOR-metric''. An id is just a path from the + root of the tree, so bits are numbered from the start. */ - if (message > REPLY) { - /* Rate limit requests. */ - if (!token_bucket()) { - debugf("Dropping request due to rate limiting.\n"); - goto dontread; - } - } +static inline int +id_cmp(const unsigned char *restrict id1, const unsigned char *restrict id2) +{ + /* Memcmp is guaranteed to perform an unsigned comparison. */ + return memcmp(id1, id2, 20); +} - switch (message) { - case REPLY: - if (tid_len != 4) { - debugf("Broken node truncates transaction ids.\n"); - goto dontread; - } - if (tid_match(tid, "pn", NULL)) { - debugf("Pong!\n"); - new_node(id, source, sourcelen, 2); - } else if (tid_match(tid, "fn", NULL)) { - debugf("Nodes found!\n"); - if (nodes_len % 26 != 0 || nodes6_len % 38 != 0) { - debugf("Unexpected length for node info!\n"); - } else { - new_node(id, source, sourcelen, 2); - for (i = 0; i < nodes_len / 26; i++) { - unsigned char *ni = nodes + i * 26; - struct sockaddr_in sin; - if (id_cmp(ni, myid) == 0) - continue; - memset(&sin, 0, sizeof(sin)); - sin.sin_family = AF_INET; - memcpy(&sin.sin_addr, ni + 20, 4); - memcpy(&sin.sin_port, ni + 24, 2); - new_node(ni, (struct sockaddr *)&sin, sizeof(sin), 0); - } - for (i = 0; i < nodes6_len / 38; i++) { - unsigned char *ni = nodes6 + i * 38; - struct sockaddr_in6 sin6; - if (id_cmp(ni, myid) == 0) - continue; - memset(&sin6, 0, sizeof(sin6)); - sin6.sin6_family = AF_INET6; - memcpy(&sin6.sin6_addr, ni + 20, 16); - memcpy(&sin6.sin6_port, ni + 36, 2); - new_node(ni, (struct sockaddr *)&sin6, sizeof(sin6), 0); - } - } - } else { - debugf("Unexpected reply!\n"); - goto dontread; - } - break; - case PING: - debugf("Ping (%d)!\n", tid_len); - new_node(id, source, sourcelen, 1); - debugf("Sending pong.\n"); - send_pong(source, sourcelen, tid, tid_len); - break; +/* Our transaction-ids are 4-bytes long, with the first two bytes identi- + fying the kind of request, and the remaining two a sequence number in + host order. */ + +static void +make_tid(unsigned char *tid_return, const char *prefix, unsigned short seqno) +{ + tid_return[0] = prefix[0] & 0xFF; + tid_return[1] = prefix[1] & 0xFF; + memcpy(tid_return + 2, &seqno, 2); +} + +static int +tid_match(const unsigned char *tid, const char *prefix, unsigned short *seqno_return) +{ + if (tid[0] == (prefix[0] & 0xFF) && tid[1] == (prefix[1] & 0xFF)) { + if (seqno_return) + memcpy(seqno_return, tid + 2, 2); + return 1; + } else + return 0; +} - case FIND_NODE: - case GET_PEERS: - if (message == FIND_NODE) - debugf("Find node!\n"); - else - debugf("Get peers!\n"); - new_node(id, source, sourcelen, 1); - debugf("Sending nodes (%d).\n", want); - send_random_nodes(source, sourcelen, tid, tid_len, target, want); - break; - case ANNOUNCE_PEER: - debugf("Announce peer!\n"); - send_error( - source, - sourcelen, - tid, - tid_len, - 203, - "This node doesn't accept announces"); - break; - } - } +static inline int +circular(int from, int to) +{ + int x = to - from; + if (x < 0) + return x + CIRCULAR_LIST_SIZE; + return x; +} - dontread: +static int +list_elements(struct circular_list *list) +{ + return circular(list->head, list->tail); +} - /* We need to be careful to avoid a positive feedback loop. Make - sure we send at most one packet each time through the select - loop. */ +static int +list_empty(struct circular_list *list) +{ + return list_elements(list) == 0; +} - if (dht_socket6 < 0) - send4 = 1; - else if (dht_socket < 0) - send4 = 0; - else - send4 = random() % 2; +static int +list_free(struct circular_list *list) +{ + return circular(list->tail + 1, list->head); +} - if (send4) { - int want = dht_socket6 >= 0 && list_free(&v6_new) > 8 ? (WANT4 | WANT6) : 0; - if (!list_empty(&v4_new)) - send_request(&v4_new, 1, list_free(&v4_new) < 8, want); - else if (!list_empty(&v4_confirmed)) - send_request(&v4_confirmed, 0, 0, want); - } else { - int want = dht_socket >= 0 && list_free(&v4_new) > 8 ? (WANT4 | WANT6) : 0; - if (!list_empty(&v6_new)) - send_request(&v6_new, 1, list_free(&v6_new) < 8, want); - else if (!list_empty(&v6_confirmed)) - send_request(&v6_confirmed, 0, 0, want); - } - } +static int +list_pop(struct circular_list *list, struct sockaddr_storage *ss, socklen_t *sslen) +{ + if (list->head == list->tail) + return 0; -usage: - fprintf(stderr, "dht-bootstrap [-q] [-4 ADDR4] [-6 ADDR6] port [node port...]\n"); - exit(EXIT_FAILURE); + memcpy(ss, &list->nodes[list->head].ss, list->nodes[list->head].sslen); + *sslen = list->nodes[list->head].sslen; + list->head = (list->head + 1) % CIRCULAR_LIST_SIZE; + return 1; } -/* We could use a proper bencoding printer and parser, but the format of - DHT messages is fairly stylised, so this seemed simpler. */ +static int +list_random( + struct circular_list *list, + unsigned char *id, + struct sockaddr_storage *ss, + socklen_t *sslen) +{ + if (list->head == list->tail) + return 0; -#define CHECK(offset, delta, size) \ - if (delta < 0 || offset + delta > size) \ - goto fail + int n = random() % (list->tail - list->head); + n = (list->head + n) % CIRCULAR_LIST_SIZE; -#define INC(offset, delta, size) \ - CHECK(offset, delta, size); \ - offset += delta + if (id) + memcpy(id, &list->nodes[n].id, 20); + memcpy(ss, &list->nodes[n].ss, list->nodes[n].sslen); + *sslen = list->nodes[n].sslen; + return 1; +} -#define COPY(buf, offset, src, delta, size) \ - CHECK(offset, delta, size); \ - memcpy(buf + offset, src, delta); \ - offset += delta; +/* We just learnt about a node, not necessarily a new one. Confirm is 1 if + the node sent a message, 2 if it sent us a reply. */ + +static int +new_node(unsigned char *id, struct sockaddr *sa, socklen_t salen, int confirm) +{ + struct circular_list *list; + if (sa->sa_family == AF_INET) + list = confirm >= 2 ? &v4_confirmed : &v4_new; + else if (sa->sa_family == AF_INET6) + list = confirm >= 2 ? &v6_confirmed : &v6_new; + else + abort(); + + /* A node that sends us a request is most probably bootstrapping. + We want to avoid getting our tables full of very young nodes -- only + include such a node if we have plenty of space. */ + + if (confirm == 1 && list_free(list) < 32) + return 0; -#define ADD_V(buf, offset, size) \ - if (have_v) { \ - COPY(buf, offset, my_v, sizeof(my_v), size); \ + for (int i = list->head; i != list->tail; i = (i + 1) % CIRCULAR_LIST_SIZE) { + struct node *n = &list->nodes[i]; + if (n->sslen == salen && memcmp(&n->ss, sa, salen) == 0) + return 0; } + memcpy(&list->nodes[list->tail].id, id, 160); + memcpy(&list->nodes[list->tail].ss, sa, salen); + list->nodes[list->tail].sslen = salen; + list->tail = (list->tail + 1) % CIRCULAR_LIST_SIZE; + if (list->head == list->tail) + list->head = (list->head + 1) % CIRCULAR_LIST_SIZE; + if (verbose) + printf("%s : new node\n", getAddr(sa, salen)); + + return 1; +} + static int -dht_send(const void *buf, size_t len, int flags, const struct sockaddr *sa, int salen) +token_bucket(void) { - int s; + time_t now = time(NULL); + if (token_bucket_tokens == 0) { + token_bucket_tokens = + MIN(MAX_TOKEN_BUCKET_TOKENS, 4 * (now - token_bucket_time)); + token_bucket_time = now; + } + if (token_bucket_tokens == 0) + return 0; + token_bucket_tokens--; + return 1; +} +static int +dht_send(const void *buf, size_t len, int flags, const struct sockaddr *sa, int salen) +{ if (salen == 0) abort(); - + int s; if (sa->sa_family == AF_INET) s = dht_socket; else if (sa->sa_family == AF_INET6) s = dht_socket6; else s = -1; - if (s < 0) { errno = EAFNOSUPPORT; return -1; } - return sendto(s, buf, len, flags, sa, salen); } -int +static int send_ping(struct sockaddr *sa, int salen, const unsigned char *tid, int tid_len) { char buf[512]; @@ -770,6 +565,8 @@ send_ping(struct sockaddr *sa, int salen, const unsigned char *tid, int tid_len) ADD_V(buf, i, 512); rc = snprintf(buf + i, 512 - i, "1:y1:qe"); INC(i, rc, 512); + if (verbose) + printf("%s <- PING\n", getAddr(sa, salen)); return dht_send(buf, i, 0, sa, salen); fail: @@ -777,12 +574,12 @@ fail: return -1; } -int +static int send_pong(struct sockaddr *sa, int salen, const unsigned char *tid, int tid_len) { char buf[512]; - int i = 0, rc; - rc = snprintf(buf + i, 512 - i, "d1:rd2:id20:"); + int i = 0; + int rc = snprintf(buf + i, 512 - i, "d1:rd2:id20:"); INC(i, rc, 512); COPY(buf, i, myid, 20, 512); rc = snprintf(buf + i, 512 - i, "e1:t%d:", tid_len); @@ -791,6 +588,8 @@ send_pong(struct sockaddr *sa, int salen, const unsigned char *tid, int tid_len) ADD_V(buf, i, 512); rc = snprintf(buf + i, 512 - i, "1:y1:re"); INC(i, rc, 512); + if (verbose) + printf("%s <- PONG\n", getAddr(sa, salen)); return dht_send(buf, i, 0, sa, salen); fail: @@ -798,7 +597,7 @@ fail: return -1; } -int +static int send_find_node( struct sockaddr *sa, int salen, @@ -807,37 +606,107 @@ send_find_node( const unsigned char *target, int want) { - char buf[512]; - int i = 0, rc; - rc = snprintf(buf + i, 512 - i, "d1:ad2:id20:"); - INC(i, rc, 512); - COPY(buf, i, myid, 20, 512); - rc = snprintf(buf + i, 512 - i, "6:target20:"); - INC(i, rc, 512); - COPY(buf, i, target, 20, 512); - if (want > 0) { - rc = snprintf( - buf + i, - 512 - i, - "4:wantl%s%se", - (want & WANT4) ? "2:n4" : "", - (want & WANT6) ? "2:n6" : ""); - INC(i, rc, 512); + char buf[512]; + int i = 0; + int rc = snprintf(buf + i, 512 - i, "d1:ad2:id20:"); + INC(i, rc, 512); + COPY(buf, i, myid, 20, 512); + rc = snprintf(buf + i, 512 - i, "6:target20:"); + INC(i, rc, 512); + COPY(buf, i, target, 20, 512); + if (want > 0) { + rc = snprintf( + buf + i, + 512 - i, + "4:wantl%s%se", + (want & WANT4) ? "2:n4" : "", + (want & WANT6) ? "2:n6" : ""); + INC(i, rc, 512); + } + rc = snprintf(buf + i, 512 - i, "e1:q9:find_node1:t%d:", tid_len); + INC(i, rc, 512); + COPY(buf, i, tid, tid_len, 512); + ADD_V(buf, i, 512); + rc = snprintf(buf + i, 512 - i, "1:y1:qe"); + INC(i, rc, 512); + if (verbose) + printf("%s <- FIND_NODE\n", getAddr(sa, salen)); + return dht_send(buf, i, 0, sa, salen); + +fail: + errno = ENOSPC; + return -1; +} + +static int +send_request(struct circular_list *list, int dopop, int doping, int want) +{ + if (list_empty(list)) + return 0; + + struct sockaddr_storage ss; + socklen_t sslen; + int rc; + if (dopop) { + rc = list_pop(list, &ss, &sslen); + if (rc == 0) + return 0; + } else { + rc = list_random(list, NULL, &ss, &sslen); + if (rc == 0) + return 0; + } + + unsigned char ttid[4]; + if (doping) { + make_tid(ttid, "pn", 0); + return send_ping((struct sockaddr *)&ss, sslen, ttid, 4); + } else { + unsigned char id[20]; + arc4random_buf(id, sizeof id); + make_tid(ttid, "fn", 0); + return send_find_node((struct sockaddr *)&ss, sslen, ttid, 4, id, want); + } +} + +static int +newSock(const char *host, const char *port) +{ + struct addrinfo hints; + memset(&hints, 0, sizeof(hints)); + hints.ai_family = AF_UNSPEC; + hints.ai_socktype = SOCK_DGRAM; + struct addrinfo *res = NULL; + int rc = getaddrinfo(host, port, &hints, &res); + if (rc != 0) + err(EXIT_FAILURE, "getaddrinfo: %s\n", gai_strerror(rc)); + int sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol); + if (sock == -1) + err(EXIT_FAILURE, "socket()"); + if (bind(sock, res->ai_addr, res->ai_addrlen) != 0) + err(EXIT_FAILURE, "bind()"); + rc = fcntl(sock, F_GETFL, 0); + if (rc < 0) + err(EXIT_FAILURE, "F_GETFL"); + rc = fcntl(sock, F_SETFL, (rc | O_NONBLOCK)); + if (rc < 0) + err(EXIT_FAILURE, "F_SETFL"); + freeaddrinfo(res); + return sock; +} + +static void +rlimited(int res) +{ + struct rlimit r; + r.rlim_cur = 0; + r.rlim_max = 0; + if (setrlimit(res, &r) == -1) { + err(EXIT_FAILURE, "can not setrlimit()"); } - rc = snprintf(buf + i, 512 - i, "e1:q9:find_node1:t%d:", tid_len); - INC(i, rc, 512); - COPY(buf, i, tid, tid_len, 512); - ADD_V(buf, i, 512); - rc = snprintf(buf + i, 512 - i, "1:y1:qe"); - INC(i, rc, 512); - return dht_send(buf, i, 0, sa, salen); - -fail: - errno = ENOSPC; - return -1; } -int +static int send_nodes( struct sockaddr *sa, int salen, @@ -849,9 +718,8 @@ send_nodes( int nodes6_len) { char buf[2048]; - int i = 0, rc; - - rc = snprintf(buf + i, 2048 - i, "d1:rd2:id20:"); + int i = 0; + int rc = snprintf(buf + i, 2048 - i, "d1:rd2:id20:"); INC(i, rc, 2048); COPY(buf, i, myid, 20, 2048); if (nodes_len > 0) { @@ -864,14 +732,12 @@ send_nodes( INC(i, rc, 2048); COPY(buf, i, nodes6, nodes6_len, 2048); } - rc = snprintf(buf + i, 2048 - i, "e1:t%d:", tid_len); INC(i, rc, 2048); COPY(buf, i, tid, tid_len, 2048); ADD_V(buf, i, 2048); rc = snprintf(buf + i, 2048 - i, "1:y1:re"); INC(i, rc, 2048); - return dht_send(buf, i, 0, sa, salen); fail: @@ -883,12 +749,6 @@ static int buffer_random_nodes(int af, unsigned char *nodes) { struct circular_list *list; - struct sockaddr_storage ss; - socklen_t sslen; - unsigned char id[20]; - int n; - int rc; - switch (af) { case AF_INET: list = &v4_confirmed; @@ -900,7 +760,11 @@ buffer_random_nodes(int af, unsigned char *nodes) abort(); } - n = 0; + struct sockaddr_storage ss; + socklen_t sslen; + unsigned char id[20]; + int rc; + int n = 0; while (n < 8) { rc = list_random(list, id, &ss, &sslen); if (rc < 1) @@ -929,28 +793,26 @@ buffer_random_nodes(int af, unsigned char *nodes) return n; } -int +static int send_random_nodes( struct sockaddr *sa, int salen, const unsigned char *tid, int tid_len, - const unsigned char *id, int want) { unsigned char nodes[8 * 26]; unsigned char nodes6[8 * 38]; - int numnodes = 0, numnodes6 = 0; - + int numnodes = 0; + int numnodes6 = 0; if (want < 0) want = sa->sa_family == AF_INET ? WANT4 : WANT6; - if ((want & WANT4)) numnodes = buffer_random_nodes(AF_INET, nodes); - if ((want & WANT6)) numnodes6 = buffer_random_nodes(AF_INET6, nodes6); - + if (verbose) + printf("%s <- NODES (%d+%d)\n", getAddr(sa, salen), numnodes, numnodes6); return send_nodes( sa, salen, tid, tid_len, nodes, numnodes * 26, nodes6, numnodes6 * 38); } @@ -965,9 +827,8 @@ send_error( const char *message) { char buf[512]; - int i = 0, rc; - - rc = snprintf(buf + i, 512 - i, "d1:eli%de%d:", code, (int)strlen(message)); + int i = 0; + int rc = snprintf(buf + i, 512 - i, "d1:eli%de%d:", code, (int)strlen(message)); INC(i, rc, 512); COPY(buf, i, message, (int)strlen(message), 512); rc = snprintf(buf + i, 512 - i, "e1:t%d:", tid_len); @@ -983,232 +844,329 @@ fail: return -1; } -#undef CHECK -#undef INC -#undef COPY -#undef ADD_V - -static int -parse_message( - const unsigned char *buf, - int buflen, - unsigned char *tid_return, - int *tid_len, - unsigned char *id_return, - unsigned char *info_hash_return, - unsigned char *target_return, - unsigned short *port_return, - unsigned char *token_return, - int *token_len, - unsigned char *nodes_return, - int *nodes_len, - unsigned char *nodes6_return, - int *nodes6_len, - unsigned char *values_return, - int *values_len, - unsigned char *values6_return, - int *values6_len, - int *want_return) +int +main(int argc, char **argv) { - const unsigned char *p; - - /* This code will happily crash if the buffer is not NUL-terminated. */ - if (buf[buflen] != '\0') { - debugf("Eek! parse_message with unterminated buffer.\n"); - return -1; - } + errno = 0; + char *ipv4addr = NULL; + char *ipv6addr = NULL; + int opt = 0; -#define CHECK(ptr, len) \ - if (((unsigned char *)ptr) + (len) > (buf) + (buflen)) \ - goto overflow; + while (1) { + opt = getopt(argc, argv, "q4:6:"); + if (opt < 0) + break; - if (tid_return) { - p = memmem(buf, buflen, "1:t", 3); - if (p) { - long l; - char *q; - l = strtol((char *)p + 3, &q, 10); - if (q && *q == ':' && l > 0 && l < *tid_len) { - CHECK(q + 1, l); - memcpy(tid_return, q + 1, l); - *tid_len = l; - } else - *tid_len = 0; - } - } - if (id_return) { - p = memmem(buf, buflen, "2:id20:", 7); - if (p) { - CHECK(p + 7, 20); - memcpy(id_return, p + 7, 20); - } else { - memset(id_return, 0, 20); + switch (opt) { + case 'q': + verbose = 0; + break; + case '4': + ipv4addr = strdup(optarg); + break; + case '6': + ipv6addr = strdup(optarg); + break; + default: + goto usage; } } - if (info_hash_return) { - p = memmem(buf, buflen, "9:info_hash20:", 14); - if (p) { - CHECK(p + 14, 20); - memcpy(info_hash_return, p + 14, 20); - } else { - memset(info_hash_return, 0, 20); - } + + int i = optind; + + if (argc < i + 1) + goto usage; + + const char *ourPort = strdup(argv[i++]); + if (ipv4addr != NULL) { + dht_socket = newSock(ipv4addr, ourPort); } - if (port_return) { - p = memmem(buf, buflen, "porti", 5); - if (p) { - long l; - char *q; - l = strtol((char *)p + 5, &q, 10); - if (q && *q == 'e' && l > 0 && l < 0x10000) - *port_return = l; - else - *port_return = 0; - } else - *port_return = 0; + if (ipv6addr != NULL) { + dht_socket6 = newSock(ipv6addr, ourPort); } - if (target_return) { - p = memmem(buf, buflen, "6:target20:", 11); - if (p) { - CHECK(p + 11, 20); - memcpy(target_return, p + 11, 20); - } else { - memset(target_return, 0, 20); + + arc4random_buf(myid, sizeof myid); + memcpy(my_v, "1:v4:JB\0\0", 9); + + int rc = 0; + unsigned char ttid[4]; + + while (i < argc) { + struct addrinfo hints, *info, *infop; + memset(&hints, 0, sizeof(hints)); + hints.ai_socktype = SOCK_DGRAM; + hints.ai_family = 0; + if (dht_socket < 0) + hints.ai_family = AF_INET6; + else if (dht_socket6 < 0) + hints.ai_family |= AF_INET; + rc = getaddrinfo(argv[i], argv[i + 1], &hints, &info); + if (rc != 0) + err(EXIT_FAILURE, "getaddrinfo: %s\n", gai_strerror(rc)); + + i++; + if (i >= argc) + goto usage; + + infop = info; + while (infop) { + make_tid(ttid, "pn", 0); + send_ping(infop->ai_addr, infop->ai_addrlen, ttid, 4); + infop = infop->ai_next; } + freeaddrinfo(info); + + i++; } - if (token_return) { - p = memmem(buf, buflen, "5:token", 7); - if (p) { - long l; - char *q; - l = strtol((char *)p + 7, &q, 10); - if (q && *q == ':' && l > 0 && l < *token_len) { - CHECK(q + 1, l); - memcpy(token_return, q + 1, l); - *token_len = l; - } else - *token_len = 0; - } else - *token_len = 0; - } - if (nodes_len) { - p = memmem(buf, buflen, "5:nodes", 7); - if (p) { - long l; - char *q; - l = strtol((char *)p + 7, &q, 10); - if (q && *q == ':' && l > 0 && l < *nodes_len) { - CHECK(q + 1, l); - memcpy(nodes_return, q + 1, l); - *nodes_len = l; - } else - *nodes_len = 0; - } else - *nodes_len = 0; - } + token_bucket_time = time(NULL); + token_bucket_tokens = MAX_TOKEN_BUCKET_TOKENS; + int send4 = 0; + struct pollfd fds[2]; + fds[0].fd = dht_socket; + fds[0].events = POLLIN; + fds[1].fd = dht_socket6; + fds[1].events = POLLIN; + + close(STDIN_FILENO); + if (!verbose) + close(STDOUT_FILENO); + rlimited(RLIMIT_NPROC); + rlimited(RLIMIT_FSIZE); +#if __FreeBSD__ + rlimited(RLIMIT_NOFILE); +#endif // __FreeBSD__ + + while (1) { + int tv_sec = 0; + if ((dht_socket >= 0 && list_elements(&v4_confirmed) <= 16) || + (dht_socket6 >= 0 && list_elements(&v6_confirmed) <= 16)) + tv_sec = 0; + else + tv_sec = random() % 30; + int tv_msec = random() % 1000; + +#ifndef __linux__ + setproctitle_fast( + "%d+%d %d+%d", + list_elements(&v4_confirmed), + list_elements(&v6_confirmed), + list_elements(&v4_new), + list_elements(&v6_new)); +#endif // __linux__ + + rc = poll(fds, 2, tv_sec * 1000 + tv_msec); + if (rc < 0) { + perror("poll"); + sleep(1); + } + + if (rc > 0) { + int message; + unsigned char tid[16], id[20], info_hash[20], target[20]; + unsigned char buf[1536], nodes[256], nodes6[1024], token[128]; + int tid_len = 16, token_len = 128; + int nodes_len = 256, nodes6_len = 1024; + unsigned short port; + unsigned char values[2048], values6[2048]; + int values_len = 2048, values6_len = 2048; + int want; + struct sockaddr_storage source_storage; + struct sockaddr *source = (struct sockaddr *)&source_storage; + socklen_t sourcelen = sizeof(source_storage); + if (fds[0].revents != 0) { + if ((fds[0].revents & (POLLERR | POLLNVAL)) > 0) { + fprintf(stderr, "error in fds[0]"); + rc = -1; + } else { + rc = recvfrom(dht_socket, buf, 1536, 0, source, &sourcelen); + } + } else if (fds[1].revents != 0) { + if ((fds[1].revents & (POLLERR | POLLNVAL)) > 0) { + fprintf(stderr, "error in fds[1]"); + rc = -1; + } else { + rc = recvfrom(dht_socket6, buf, 1536, 0, source, &sourcelen); + } + } - if (nodes6_len) { - p = memmem(buf, buflen, "6:nodes6", 8); - if (p) { - long l; - char *q; - l = strtol((char *)p + 8, &q, 10); - if (q && *q == ':' && l > 0 && l < *nodes6_len) { - CHECK(q + 1, l); - memcpy(nodes6_return, q + 1, l); - *nodes6_len = l; - } else - *nodes6_len = 0; - } else - *nodes6_len = 0; - } + if (rc < 0 || sourcelen > sizeof(struct sockaddr_storage)) + goto dontread; - if (values_len || values6_len) { - p = memmem(buf, buflen, "6:valuesl", 9); - if (p) { - int i = p - buf + 9; - int j = 0, j6 = 0; - while (1) { - long l; - char *q; - l = strtol((char *)buf + i, &q, 10); - if (q && *q == ':' && l > 0) { - CHECK(q + 1, l); - if (l == 6) { - if (j + l > *values_len) - continue; - i = q + 1 + l - (char *)buf; - memcpy((char *)values_return + j, q + 1, l); - j += l; - } else if (l == 18) { - if (j6 + l > *values6_len) - continue; - i = q + 1 + l - (char *)buf; - memcpy((char *)values6_return + j6, q + 1, l); - j6 += l; + if (is_martian(source)) + goto dontread; + + /* There's a bug in parse_message -- it will happily overflow the + buffer if it's not NUL-terminated. For now, put a NUL at the + end of buffers. */ + + if (rc < 1536) { + buf[rc] = '\0'; + } else { + if (verbose) + printf("%s : overlong message\n", getAddr(source, sourcelen)); + goto dontread; + } + + message = parse_message( + buf, + rc, + tid, + &tid_len, + id, + info_hash, + target, + &port, + token, + &token_len, + nodes, + &nodes_len, + nodes6, + &nodes6_len, + values, + &values_len, + values6, + &values6_len, + &want, + source, + sourcelen); + + if (id_cmp(id, myid) == 0) { + if (verbose) + printf( + "%s : received message from self\n", + getAddr(source, sourcelen)); + goto dontread; + } + + if (message > REPLY) { + /* Rate limit requests. */ + if (!token_bucket()) { + if (verbose) + printf( + "%s : dropping request due to rate limiting.\n", + getAddr(source, sourcelen)); + goto dontread; + } + } + + switch (message) { + case REPLY: + if (tid_len != 4) { + if (verbose) + printf( + "%s : broken node truncates transaction ids\n", + getAddr(source, sourcelen)); + goto dontread; + } + if (tid_match(tid, "pn", NULL)) { + if (verbose) + printf("%s -> PONG\n", getAddr(source, sourcelen)); + new_node(id, source, sourcelen, 2); + } else if (tid_match(tid, "fn", NULL)) { + if (verbose) + printf( + "%s -> NODES (%d+%d)\n", + getAddr(source, sourcelen), + nodes_len / 26, + nodes6_len / 38); + if (nodes_len % 26 != 0 || nodes6_len % 38 != 0) { + if (verbose) + printf( + "%s : unexpected length for node info\n", + getAddr(source, sourcelen)); } else { - debugf("Received weird value -- %d bytes.\n", (int)l); - i = q + 1 + l - (char *)buf; + new_node(id, source, sourcelen, 2); + for (i = 0; i < nodes_len / 26; i++) { + unsigned char *ni = nodes + i * 26; + struct sockaddr_in sin; + if (id_cmp(ni, myid) == 0) + continue; + memset(&sin, 0, sizeof(sin)); + sin.sin_family = AF_INET; + memcpy(&sin.sin_addr, ni + 20, 4); + memcpy(&sin.sin_port, ni + 24, 2); + new_node(ni, (struct sockaddr *)&sin, sizeof(sin), 0); + } + for (i = 0; i < nodes6_len / 38; i++) { + unsigned char *ni = nodes6 + i * 38; + struct sockaddr_in6 sin6; + if (id_cmp(ni, myid) == 0) + continue; + memset(&sin6, 0, sizeof(sin6)); + sin6.sin6_family = AF_INET6; + memcpy(&sin6.sin6_addr, ni + 20, 16); + memcpy(&sin6.sin6_port, ni + 36, 2); + new_node(ni, (struct sockaddr *)&sin6, sizeof(sin6), 0); + } } } else { - break; + if (verbose) + printf("%s : unexpected reply\n", getAddr(source, sourcelen)); + goto dontread; + } + break; + case PING: + if (verbose) + printf("%s -> PING (%d)\n", getAddr(source, sourcelen), tid_len); + new_node(id, source, sourcelen, 1); + send_pong(source, sourcelen, tid, tid_len); + break; + + case FIND_NODE: + case GET_PEERS: + if (verbose) { + if (message == FIND_NODE) + printf("%s -> FIND_NODE\n", getAddr(source, sourcelen)); + else + printf("%s -> GET_PEERS\n", getAddr(source, sourcelen)); } + new_node(id, source, sourcelen, 1); + send_random_nodes(source, sourcelen, tid, tid_len, want); + break; + case ANNOUNCE_PEER: + if (verbose) + printf("%s -> ANNOUNCE_PEER\n", getAddr(source, sourcelen)); + send_error( + source, + sourcelen, + tid, + tid_len, + 203, + "This node doesn't accept announces"); + break; } - if (i >= buflen || buf[i] != 'e') - debugf("eek... unexpected end for values.\n"); - if (values_len) - *values_len = j; - if (values6_len) - *values6_len = j6; - } else { - *values_len = 0; - *values6_len = 0; } - } - if (want_return) { - p = memmem(buf, buflen, "4:wantl", 7); - if (p) { - int i = p - buf + 7; - *want_return = 0; - while (buf[i] > '0' && buf[i] <= '9' && buf[i + 1] == ':' && - i + 2 + buf[i] - '0' < buflen) { - CHECK(buf + i + 2, buf[i] - '0'); - if (buf[i] == '2' && memcmp(buf + i + 2, "n4", 2) == 0) - *want_return |= WANT4; - else if (buf[i] == '2' && memcmp(buf + i + 2, "n6", 2) == 0) - *want_return |= WANT6; - else - debugf("eek... unexpected want flag (%c)\n", buf[i]); - i += 2 + buf[i] - '0'; - } - if (i >= buflen || buf[i] != 'e') - debugf("eek... unexpected end for want.\n"); + dontread: + + /* We need to be careful to avoid a positive feedback loop. Make + sure we send at most one packet each time through the select + loop. */ + + if (dht_socket6 < 0) + send4 = 1; + else if (dht_socket < 0) + send4 = 0; + else + send4 = random() % 2; + + if (send4) { + int want = dht_socket6 >= 0 && list_free(&v6_new) > 8 ? (WANT4 | WANT6) : 0; + if (!list_empty(&v4_new)) + send_request(&v4_new, 1, list_free(&v4_new) < 8, want); + else if (!list_empty(&v4_confirmed)) + send_request(&v4_confirmed, 0, 0, want); } else { - *want_return = -1; + int want = dht_socket >= 0 && list_free(&v4_new) > 8 ? (WANT4 | WANT6) : 0; + if (!list_empty(&v6_new)) + send_request(&v6_new, 1, list_free(&v6_new) < 8, want); + else if (!list_empty(&v6_confirmed)) + send_request(&v6_confirmed, 0, 0, want); } } -#undef CHECK - - if (memmem(buf, buflen, "1:y1:r", 6)) - return REPLY; - if (memmem(buf, buflen, "1:y1:e", 6)) - return ERROR; - if (!memmem(buf, buflen, "1:y1:q", 6)) - return -1; - if (memmem(buf, buflen, "1:q4:ping", 9)) - return PING; - if (memmem(buf, buflen, "1:q9:find_node", 14)) - return FIND_NODE; - if (memmem(buf, buflen, "1:q9:get_peers", 14)) - return GET_PEERS; - if (memmem(buf, buflen, "1:q13:announce_peer", 19)) - return ANNOUNCE_PEER; - return -1; - -overflow: - debugf("Truncated message.\n"); - return -1; +usage: + fprintf(stderr, "dht-bootstrap [-q] [-4 ADDR4] [-6 ADDR6] port [node port...]\n"); + exit(EXIT_FAILURE); } -- 2.44.0