diff options
| -rw-r--r-- | libc/inet/resolv.c | 72 |
1 files changed, 39 insertions, 33 deletions
diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c index ce19c8698..7bc46f227 100644 --- a/libc/inet/resolv.c +++ b/libc/inet/resolv.c @@ -398,6 +398,10 @@ int attribute_hidden __encode_dotted(const char *dotted, unsigned char *dest, in char *c = strchr(dotted, '.'); int l = c ? c - dotted : strlen(dotted); + /* two consecutive dots are not valid */ + if (l == 0) + return -1; + if (l >= (maxlen - used - 1)) return -1; @@ -746,8 +750,9 @@ int attribute_hidden __dns_lookup(const char *name, int type, int nscount, char unsigned retries = 0; unsigned char * packet = malloc(PACKETSZ); char *dns, *lookup = malloc(MAXDNAME); - int variant = -1; + int variant = -1; /* search domain to append, -1 - none */ int local_ns = -1, local_id = -1; + bool ends_with_dot; #ifdef __UCLIBC_HAS_IPV6__ bool v6; struct sockaddr_in6 sa6; @@ -758,11 +763,13 @@ int attribute_hidden __dns_lookup(const char *name, int type, int nscount, char fd = -1; - if (!packet || !lookup || !nscount) + if (!packet || !lookup || !nscount || !name[0]) goto fail; DPRINTF("Looking up type %d answer for '%s'\n", type, name); + ends_with_dot = (name[strlen(name) - 1] == '.'); + /* Mess with globals while under lock */ __UCLIBC_MUTEX_LOCK(mylock); local_ns = static_ns % nscount; @@ -780,12 +787,6 @@ int attribute_hidden __dns_lookup(const char *name, int type, int nscount, char ++local_id; local_id &= 0xffff; h.id = local_id; - __UCLIBC_MUTEX_LOCK(__resolv_lock); - /* this is really __nameserver[] which is a global that - needs to hold __resolv_lock before access!! */ - dns = nsip[local_ns]; - __UCLIBC_MUTEX_UNLOCK(__resolv_lock); - h.qdcount = 1; h.rd = 1; @@ -796,14 +797,23 @@ int attribute_hidden __dns_lookup(const char *name, int type, int nscount, char goto fail; strncpy(lookup, name, MAXDNAME); + __UCLIBC_MUTEX_LOCK(__resolv_lock); + /* nsip is really __nameserver[] which is a global that + needs to hold __resolv_lock before access!! */ + dns = nsip[local_ns]; +/* TODO: all future accesses to 'dns' are guarded by __resolv_lock too. + * Why? We already fetched nsip[local_ns] here, + * future changes to nsip[] by other threads cannot affect us. + * We can use 'dns' without locking. If I'm wrong, + * please explain in comments why locking is needed. */ if (variant >= 0) { - __UCLIBC_MUTEX_LOCK(__resolv_lock); if (variant < __searchdomains) { strncat(lookup, ".", MAXDNAME); strncat(lookup, __searchdomain[variant], MAXDNAME); } - __UCLIBC_MUTEX_UNLOCK(__resolv_lock); } + __UCLIBC_MUTEX_UNLOCK(__resolv_lock); + DPRINTF("lookup name: %s\n", lookup); q.dotted = (char *)lookup; q.qtype = type; @@ -994,19 +1004,18 @@ int attribute_hidden __dns_lookup(const char *name, int type, int nscount, char tryall: /* if there are other nameservers, give them a go, otherwise return with error */ - { - variant = -1; - local_ns = (local_ns + 1) % nscount; - if (local_ns == 0) - retries++; + variant = -1; + local_ns = (local_ns + 1) % nscount; + if (local_ns == 0) + retries++; - continue; - } + continue; again: /* if there are searchdomains, try them or fallback as passed */ - { + if (!ends_with_dot) { int sdomains; + __UCLIBC_MUTEX_LOCK(__resolv_lock); sdomains = __searchdomains; __UCLIBC_MUTEX_UNLOCK(__resolv_lock); @@ -1014,15 +1023,14 @@ int attribute_hidden __dns_lookup(const char *name, int type, int nscount, char if (variant < sdomains - 1) { /* next search */ variant++; - } else { - /* next server, first search */ - local_ns = (local_ns + 1) % nscount; - if (local_ns == 0) - retries++; - - variant = -1; + continue; } } + /* next server, first search */ + local_ns = (local_ns + 1) % nscount; + if (local_ns == 0) + retries++; + variant = -1; } fail: @@ -1267,10 +1275,10 @@ int res_query(const char *dname, int class, int type, __open_nameservers(); if (!dname || class != 1 /* CLASS_IN */) { h_errno = NO_RECOVERY; - return(-1); + return -1; } - memset((char *) &a, '\0', sizeof(a)); + memset(&a, '\0', sizeof(a)); __UCLIBC_MUTEX_LOCK(__resolv_lock); __nameserversXX = __nameservers; @@ -1280,16 +1288,14 @@ int res_query(const char *dname, int class, int type, if (i < 0) { h_errno = TRY_AGAIN; - return(-1); + return -1; } free(a.dotted); - if (a.atype == type) { /* CNAME*/ - int len = MIN(anslen, i); - memcpy(answer, packet, len); - free(packet); - return(len); + if (a.atype == type) { /* CNAME */ + i = MIN(anslen, i); + memcpy(answer, packet, i); } free(packet); return i; |