diff options
| -rw-r--r-- | src/or/dns.c | 70 |
1 files changed, 47 insertions, 23 deletions
diff --git a/src/or/dns.c b/src/or/dns.c index 1f62414ab..3112de3ac 100644 --- a/src/or/dns.c +++ b/src/or/dns.c @@ -16,16 +16,13 @@ #define MIN_DNSWORKERS 3 #define MAX_IDLE_DNSWORKERS 10 +#define DNS_RESOLVE_FAILED_TRANSIENT 1 +#define DNS_RESOLVE_FAILED_PERMANENT 2 +#define DNS_RESOLVE_SUCCEEDED 3 + int num_dnsworkers=0; int num_dnsworkers_busy=0; -static void purge_expired_resolves(uint32_t now); -static int assign_to_dnsworker(connection_t *exitconn); -static void dns_found_answer(char *address, uint32_t addr); -int dnsworker_main(void *data); -static int spawn_dnsworker(void); -static void spawn_enough_dnsworkers(void); - struct pending_connection_t { struct connection_t *conn; struct pending_connection_t *next; @@ -44,6 +41,14 @@ struct cached_resolve { struct cached_resolve *next; }; +static void purge_expired_resolves(uint32_t now); +static int assign_to_dnsworker(connection_t *exitconn); +static void dns_purge_resolve(struct cached_resolve *resolve); +static void dns_found_answer(char *address, uint32_t addr, char outcome); +int dnsworker_main(void *data); +static int spawn_dnsworker(void); +static void spawn_enough_dnsworkers(void); + static SPLAY_HEAD(cache_tree, cached_resolve) cache_root; static int compare_cached_resolves(struct cached_resolve *a, @@ -238,7 +243,7 @@ void connection_dns_remove(connection_t *conn) void dns_cancel_pending_resolve(char *address) { struct pending_connection_t *pend; struct cached_resolve search; - struct cached_resolve *resolve, *tmp; + struct cached_resolve *resolve; connection_t *pendconn; strncpy(search.address, address, MAX_ADDRESSLEN); @@ -266,6 +271,12 @@ void dns_cancel_pending_resolve(char *address) { tor_free(pend); } + dns_purge_resolve(resolve); +} + +static void dns_purge_resolve(struct cached_resolve *resolve) { + struct cached_resolve *tmp; + /* remove resolve from the linked list */ if(resolve == oldest_cached_resolve) { oldest_cached_resolve = resolve->next; @@ -287,7 +298,7 @@ void dns_cancel_pending_resolve(char *address) { tor_free(resolve); } -static void dns_found_answer(char *address, uint32_t addr) { +static void dns_found_answer(char *address, uint32_t addr, char outcome) { struct pending_connection_t *pend; struct cached_resolve search; struct cached_resolve *resolve; @@ -316,7 +327,7 @@ static void dns_found_answer(char *address, uint32_t addr) { /* assert(resolve->state == CACHE_STATE_PENDING); */ resolve->addr = ntohl(addr); - if(resolve->addr) + if(outcome == DNS_RESOLVE_SUCCEEDED) resolve->state = CACHE_STATE_VALID; else resolve->state = CACHE_STATE_FAILED; @@ -337,6 +348,10 @@ static void dns_found_answer(char *address, uint32_t addr) { resolve->pending_connections = pend->next; tor_free(pend); } + + if(outcome == DNS_RESOLVE_FAILED_TRANSIENT) { /* remove from cache */ + dns_purge_resolve(resolve); + } } /******************************************************************/ @@ -348,6 +363,7 @@ int connection_dns_finished_flushing(connection_t *conn) { } int connection_dns_process_inbuf(connection_t *conn) { + char answer[5]; uint32_t addr; assert(conn && conn->type == CONN_TYPE_DNSWORKER); @@ -364,16 +380,19 @@ int connection_dns_process_inbuf(connection_t *conn) { } assert(conn->state == DNSWORKER_STATE_BUSY); - if(buf_datalen(conn->inbuf) < 4) /* entire answer available? */ + if(buf_datalen(conn->inbuf) < 5) /* entire answer available? */ return 0; /* not yet */ - assert(buf_datalen(conn->inbuf) == 4); + assert(buf_datalen(conn->inbuf) == 5); - connection_fetch_from_buf((char*)&addr,sizeof(addr),conn); + connection_fetch_from_buf(answer,sizeof(answer),conn); + addr = *(uint32_t*)(answer+1); log_fn(LOG_DEBUG, "DNSWorker (fd %d) returned answer for '%s'", conn->s, conn->address); - dns_found_answer(conn->address, addr); + assert(answer[0] >= DNS_RESOLVE_FAILED_TRANSIENT); + assert(answer[0] <= DNS_RESOLVE_SUCCEEDED); + dns_found_answer(conn->address, addr, answer[0]); tor_free(conn->address); conn->address = tor_strdup("<idle>"); @@ -386,6 +405,7 @@ int connection_dns_process_inbuf(connection_t *conn) { int dnsworker_main(void *data) { char address[MAX_ADDRESSLEN]; unsigned char address_len; + char answer[5]; struct hostent *rent; int *fdarray = data; int fd; @@ -398,7 +418,6 @@ int dnsworker_main(void *data) { for(;;) { if(recv(fd, &address_len, 1, 0) != 1) { -// log_fn(LOG_INFO,"read length failed. Child exiting."); log_fn(LOG_INFO,"dnsworker exiting because tor process died."); spawn_exit(); } @@ -412,19 +431,24 @@ int dnsworker_main(void *data) { rent = gethostbyname(address); if (!rent) { - log_fn(LOG_INFO,"Could not resolve dest addr %s. Returning nulls.",address); - if(write_all(fd, "\0\0\0\0", 4, 1) != 4) { - log_fn(LOG_ERR,"writing nulls failed. Child exiting."); - spawn_exit(); + if(h_errno == TRY_AGAIN) { /* transient error -- don't cache it */ + log_fn(LOG_INFO,"Could not resolve dest addr %s (transient).",address); + answer[0] = DNS_RESOLVE_FAILED_TRANSIENT; + } else { /* permanent error, can be cached */ + log_fn(LOG_INFO,"Could not resolve dest addr %s (permanent).",address); + answer[0] = DNS_RESOLVE_FAILED_PERMANENT; } + memset(answer+1,0,4); } else { assert(rent->h_length == 4); /* break to remind us if we move away from ipv4 */ - if(write_all(fd, rent->h_addr, 4, 1) != 4) { - log_fn(LOG_INFO,"writing answer failed. Child exiting."); - spawn_exit(); - } + answer[0] = DNS_RESOLVE_SUCCEEDED; + memcpy(answer+1, rent->h_addr, 4); log_fn(LOG_INFO,"Resolved address '%s'.",address); } + if(write_all(fd, answer, 5, 1) != 5) { + log_fn(LOG_ERR,"writing answer failed. Child exiting."); + spawn_exit(); + } } return 0; /* windows wants this function to return an int */ } |