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authorLaurent Bercot <ska-skaware@skarnet.org>2014-12-10 03:05:47 +0000
committerLaurent Bercot <ska-skaware@skarnet.org>2014-12-10 03:05:47 +0000
commit416ef5e2bf59bb2e45066a1d5d91ac677c0f48e5 (patch)
tree1c746d673dcec7a8488c6ac51db8245411034376 /src/libs6dns/s6dns_engine.c
downloads6-dns-416ef5e2bf59bb2e45066a1d5d91ac677c0f48e5.tar.xz
Initial commit
Diffstat (limited to 'src/libs6dns/s6dns_engine.c')
-rw-r--r--src/libs6dns/s6dns_engine.c372
1 files changed, 372 insertions, 0 deletions
diff --git a/src/libs6dns/s6dns_engine.c b/src/libs6dns/s6dns_engine.c
new file mode 100644
index 0000000..4145ef7
--- /dev/null
+++ b/src/libs6dns/s6dns_engine.c
@@ -0,0 +1,372 @@
+/* ISC license. */
+
+#include <errno.h>
+#include <skalibs/uint16.h>
+#include <skalibs/uint32.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/error.h>
+#include <skalibs/tai.h>
+#include <skalibs/stralloc.h>
+#include <skalibs/mininetstring.h>
+#include <skalibs/socket.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/ip46.h>
+#include <skalibs/random.h>
+#include <s6-dns/s6dns-constants.h>
+#include <s6-dns/s6dns-message-internal.h>
+#include <s6-dns/s6dns-message.h>
+#include <s6-dns/s6dns-engine.h>
+
+
+ /* Utility functions */
+
+static inline int qdomain_diff (char const *s1, unsigned int n1, char const *s2, unsigned int n2)
+{
+ return (n1 < n2) ? -1 : (n1 > n2) ? 1 : case_diffb(s1, n1, s2) ;
+}
+
+static int relevant (char const *q, unsigned int qlen, char const *ans, unsigned int anslen, int strict)
+{
+ {
+ s6dns_message_header_t h ;
+ uint16 id ;
+ s6dns_message_header_unpack(ans, &h) ;
+ if (!h.qr || h.opcode || h.z || (h.counts.qd != 1)) return 0 ;
+ if (h.rd != (q[2] & 1)) return 0 ;
+ if (strict && !h.aa && !(q[2] & 1)) return 0 ;
+ uint16_unpack_big(q, &id) ;
+ if (id != h.id) return 0 ;
+ }
+ {
+ char buf[255] ;
+ unsigned int pos = 12 ;
+ unsigned int n = s6dns_message_get_domain_internal(buf, 255, ans, anslen, &pos) ;
+ if (!n) return -1 ;
+ if (pos + 4 > anslen) return (errno = EPROTO, -1) ;
+ if (qdomain_diff(buf, n, q + 12, qlen - 16)) return 0 ;
+ if (byte_diff(q + qlen - 4, 4, ans + pos)) return 0 ;
+ }
+ return 1 ;
+}
+
+
+ /* Network core functions: transport-dependent */
+
+#ifdef SKALIBS_IPV6_ENABLED
+# define socketbind46(fd, ip, port, flag) ((flag) ? socket_bind6(fd, ip, port) : socket_bind4(fd, ip, port))
+# define socketudp46(flag) ((flag) ? socket_udp6() : socket_udp4())
+# define sockettcp46(flag) ((flag) ? socket_tcp6() : socket_tcp4())
+# define socketconnect46(fd, ip, port, flag) ((flag) ? socket_connect6(fd, ip, port) : socket_connect4(fd, ip, port))
+# define S6DNS_ENGINE_LOCAL0 IP6_ANY
+#else
+# define socketbind46(fd, ip, port, flag) ((void)(flag), socket_bind4(fd, ip, port))
+# define socketudp46(flag) socket_udp4()
+# define sockettcp46(flag) socket_tcp4()
+# define socketconnect46(fd, ip, port, flag) socket_connect4(fd, ip, port)
+# define S6DNS_ENGINE_LOCAL0 "\0\0\0"
+#endif
+
+static int randombind (int fd, int flag)
+{
+ register unsigned int i = 0 ;
+ for (; i < 10 ; i++)
+ if (socketbind46(fd, S6DNS_ENGINE_LOCAL0, 1025 + badrandom_int(64510), flag) >= 0) return 1 ;
+ return (socketbind46(fd, S6DNS_ENGINE_LOCAL0, 0, flag) >= 0) ;
+}
+
+static int thisudp (s6dns_engine_t *dt, tain_t const *stamp)
+{
+ for (;; dt->curserver++)
+ {
+ if (dt->curserver >= S6DNS_MAX_SERVERS)
+ {
+ dt->curserver = 0 ;
+ if (++dt->protostate >= 4) return -1 ;
+ }
+ if (byte_diff(s6dns_ip46list_ip(&dt->servers, dt->curserver), SKALIBS_IP_SIZE, S6DNS_ENGINE_LOCAL0)) break ;
+ }
+ if (badrandom_string(dt->sa.s + 2, 2) < 2) return 0 ; /* random query id */
+ dt->fd = socketudp46(s6dns_ip46list_is6(&dt->servers, dt->curserver)) ;
+ if (dt->fd < 0) return 0 ;
+ if (!randombind(dt->fd, s6dns_ip46list_is6(&dt->servers, dt->curserver))) goto err ; /* random source port */
+ if ((socketconnect46(dt->fd, s6dns_ip46list_ip(&dt->servers, dt->curserver), 53, s6dns_ip46list_is6(&dt->servers, dt->curserver)) < 0)
+ && (errno != EINPROGRESS)) goto err ;
+ tain_add(&dt->localdeadline, stamp, &tain_infinite_relative) ;
+ dt->flagreading = 0 ;
+ dt->flagwriting = 1 ;
+ if (dt->debughook && dt->debughook->pre_send) (*dt->debughook->pre_send)(dt, dt->debughook->external) ;
+ return 1 ;
+ err:
+ {
+ register int e = errno ;
+ fd_close(dt->fd) ; dt->fd = -1 ;
+ errno = e ;
+ }
+ return 0 ;
+}
+
+static int thistcp (s6dns_engine_t *dt, tain_t const *stamp)
+{
+ for (; dt->curserver < S6DNS_MAX_SERVERS ; dt->curserver++)
+ if (byte_diff(s6dns_ip46list_ip(&dt->servers, dt->curserver), SKALIBS_IP_SIZE, S6DNS_ENGINE_LOCAL0)) break ;
+ if (dt->curserver >= S6DNS_MAX_SERVERS) return -1 ;
+ if (badrandom_string(dt->sa.s + 2, 2) < 2) return 0 ; /* random query id */
+ dt->fd = sockettcp46(s6dns_ip46list_is6(&dt->servers, dt->curserver)) ;
+ if (dt->fd < 0) return 0 ;
+ if (!randombind(dt->fd, s6dns_ip46list_is6(&dt->servers, dt->curserver))) goto err ; /* random source port */
+ if ((socketconnect46(dt->fd, s6dns_ip46list_ip(&dt->servers, dt->curserver), 53, s6dns_ip46list_is6(&dt->servers, dt->curserver)) < 0)
+ && (errno != EINPROGRESS)) goto err ;
+ tain_addsec(&dt->localdeadline, stamp, 10) ;
+ dt->protostate = 0 ;
+ dt->flagtcp = dt->flagconnecting = dt->flagwriting = 1 ;
+ dt->flagreading = 0 ;
+ if (dt->debughook && dt->debughook->pre_send) (*dt->debughook->pre_send)(dt, dt->debughook->external) ;
+ return 1 ;
+ err:
+ {
+ register int e = errno ;
+ fd_close(dt->fd) ; dt->fd = -1 ;
+ errno = e ;
+ }
+ return 0 ;
+}
+
+
+ /* all the rest is transport-agnostic */
+
+static int s6dns_engine_prepare (s6dns_engine_t *dt, tain_t const *stamp, int istcp)
+{
+ for (;; dt->curserver++)
+ switch (istcp ? thistcp(dt, stamp) : thisudp(dt, stamp))
+ {
+ case -1 : return (errno = ENETUNREACH, 0) ;
+ case 0 : break ;
+ case 1 : return 1 ;
+ default : return (errno = EDOM, 0) ; /* can't happen */
+ }
+}
+
+static void prepare_next (s6dns_engine_t *dt, tain_t const *stamp, int istcp)
+{
+ if (!error_isagain(errno))
+ {
+ fd_close(dt->fd) ;
+ dt->curserver++ ;
+ if (s6dns_engine_prepare(dt, stamp, istcp)) errno = EAGAIN ;
+ }
+}
+
+static int s6dns_engine_write_udp (s6dns_engine_t *dt, tain_t const *stamp)
+{
+ static unsigned int const s6dns_engine_udp_timeouts[4] = { 1, 3, 11, 45 } ;
+ if (fd_send(dt->fd, dt->sa.s + 2, dt->querylen - 2, 0) < (int)(dt->querylen - 2))
+ return (prepare_next(dt, stamp, 0), 0) ;
+ tain_addsec(&dt->localdeadline, stamp, s6dns_engine_udp_timeouts[dt->protostate]) ;
+ dt->flagwriting = 0 ;
+ dt->flagreading = 1 ;
+ if (dt->debughook && dt->debughook->post_send) (*dt->debughook->post_send)(dt, dt->debughook->external) ;
+ return (errno = EAGAIN, 1) ;
+}
+
+static int s6dns_engine_write_tcp (s6dns_engine_t *dt, tain_t const *stamp)
+{
+ unsigned int r ;
+ r = allwrite(dt->fd, dt->sa.s + dt->protostate, dt->querylen - dt->protostate) ;
+ dt->protostate += r ;
+ if (r) dt->flagconnecting = 0 ;
+ if (dt->protostate < dt->sa.len)
+ {
+ if ((errno == ECONNRESET) && dt->flagconnecting) errno = EAGAIN ;
+ prepare_next(dt, stamp, 1) ;
+ return 0 ;
+ }
+ dt->protostate = 0 ;
+ tain_addsec(&dt->localdeadline, stamp, 10) ;
+ dt->flagwriting = 0 ;
+ dt->flagreading = 1 ;
+ if (dt->debughook && dt->debughook->post_send) (*dt->debughook->post_send)(dt, dt->debughook->external) ;
+ return (errno = EAGAIN, 1) ;
+}
+
+static int s6dns_engine_read_udp (s6dns_engine_t *dt, tain_t const *stamp)
+{
+ s6dns_message_header_t h ;
+ char buf[513] ;
+ register int r = fd_recv(dt->fd, buf, 513, 0) ;
+ if (r < 0) return (prepare_next(dt, stamp, 0), 0) ;
+ if ((r > 512) || (r < 12)) return (errno = EAGAIN, 0) ;
+ switch (relevant(dt->sa.s + 2, dt->querylen - 2, buf, r, dt->flagstrict))
+ {
+ case -1 : if (!dt->flagstrict) prepare_next(dt, stamp, 0) ; return 0 ;
+ case 0 : return (errno = EAGAIN, 0) ;
+ case 1 : break ;
+ default : return (errno = EDOM, 0) ; /* can't happen */
+ }
+ if (dt->debughook && dt->debughook->post_recv)
+ {
+ if (!stralloc_catb(&dt->sa, buf, r)) return 0 ;
+ (*dt->debughook->post_recv)(dt, dt->debughook->external) ;
+ dt->sa.len = dt->querylen ;
+ }
+ s6dns_message_header_unpack(buf, &h) ;
+ if (h.tc)
+ {
+ fd_close(dt->fd) ;
+ dt->curserver = 0 ;
+ dt->protostate = 0 ;
+ if (s6dns_engine_prepare(dt, stamp, 1)) errno = EAGAIN ;
+ return 0 ;
+ }
+ switch (h.rcode)
+ {
+ case 0 : case 3 : break ; /* normal operation */
+ case 1 : case 4 : case 5 :
+ byte_zero(s6dns_ip46list_ip(&dt->servers, dt->curserver), SKALIBS_IP_SIZE) ; /* do not query it again */
+ default : prepare_next(dt, stamp, 0) ; return 0 ;
+ }
+ if (!stralloc_copyb(&dt->sa, buf, r))
+ {
+ register int e = errno ;
+ fd_close(dt->fd) ; dt->fd = -1 ;
+ errno = e ;
+ return 0 ;
+ }
+ dt->querylen = 0 ;
+ fd_close(dt->fd) ; dt->fd = -1 ;
+ dt->flagreading = 0 ;
+ return 1 ;
+}
+
+static int s6dns_engine_read_tcp (s6dns_engine_t *dt, tain_t const *stamp)
+{
+ register int r = sanitize_read(mininetstring_read(dt->fd, &dt->sa, &dt->protostate)) ;
+ if (r < 0) return (prepare_next(dt, stamp, 1), 0) ;
+ else if (!r) return (errno = EAGAIN, 0) ;
+ else if ((dt->sa.len - dt->querylen) < 12)
+ {
+ errno = EPROTO ;
+ goto badanswer ;
+ }
+ else
+ {
+ s6dns_message_header_t h ;
+ switch (relevant(dt->sa.s + 2, dt->querylen - 2, dt->sa.s + dt->querylen, dt->sa.len - dt->querylen, dt->flagstrict))
+ {
+ case -1 : if (dt->flagstrict) { dt->sa.len = dt->querylen ; return 0 ; }
+ case 0 : goto badanswer ;
+ case 1 : break ;
+ default : dt->sa.len = dt->querylen ; return (errno = EDOM, 0) ; /* can't happen */
+ }
+ if (dt->debughook && dt->debughook->post_recv) (*dt->debughook->post_recv)(dt, dt->debughook->external) ;
+ s6dns_message_header_unpack(dt->sa.s + dt->querylen, &h) ;
+ if (h.tc) goto badanswer ;
+ switch (h.rcode)
+ {
+ case 0 : case 3 : break ; /* normal operation */
+ case 1 : case 4 : case 5 :
+ byte_zero(s6dns_ip46list_ip(&dt->servers, dt->curserver), SKALIBS_IP_SIZE) ; /* do not query it again */
+ default : goto badanswer ;
+ }
+ fd_close(dt->fd) ; dt->fd = -1 ;
+ dt->flagreading = 0 ;
+ return 1 ;
+ }
+ badanswer:
+ dt->sa.len = dt->querylen ;
+ prepare_next(dt, stamp, 1) ;
+ return 0 ;
+}
+
+
+void s6dns_engine_recycle (s6dns_engine_t *dt)
+{
+ dt->sa.len = 0 ;
+ dt->querylen = 0 ;
+ byte_zero(&dt->servers, sizeof(s6dns_ip46list_t)) ;
+ if (dt->fd >= 0)
+ {
+ register int e = errno ;
+ fd_close(dt->fd) ;
+ dt->fd = -1 ;
+ errno = e ;
+ }
+ dt->status = ECONNABORTED ;
+ dt->flagstrict = dt->flagtcp = dt->flagconnecting = dt->flagreading = dt->flagwriting = 0 ;
+}
+
+int s6dns_engine_timeout (s6dns_engine_t *dt, tain_t const *stamp)
+{
+ if (!error_isagain(dt->status)) return (errno = EINVAL, -1) ;
+ else if (tain_less(&dt->deadline, stamp)) goto yes ;
+ else if (!tain_less(&dt->localdeadline, stamp)) return 0 ;
+ else if (dt->flagwriting) goto yes ;
+ else if (!dt->flagreading) return 0 ;
+ fd_close(dt->fd) ;
+ dt->curserver++ ;
+ if (!s6dns_engine_prepare(dt, stamp, dt->flagtcp))
+ {
+ s6dns_engine_recycle(dt) ;
+ dt->status = errno ;
+ return -1 ;
+ }
+ return 0 ;
+ yes:
+ s6dns_engine_recycle(dt) ;
+ dt->status = ETIMEDOUT ;
+ return 1 ;
+}
+
+int s6dns_engine_event (s6dns_engine_t *dt, tain_t const *stamp)
+{
+ if (!error_isagain(dt->status)) return (errno = EINVAL, -1) ;
+ if (dt->flagwriting)
+ dt->flagtcp ? s6dns_engine_write_tcp(dt, stamp) : s6dns_engine_write_udp(dt, stamp) ;
+ else if (dt->flagreading)
+ {
+ if ((dt->flagtcp) ? s6dns_engine_read_tcp(dt, stamp) : s6dns_engine_read_udp(dt, stamp))
+ {
+ dt->status = 0 ;
+ return 1 ;
+ }
+ }
+ else return (errno = EINVAL, -1) ;
+ if (error_isagain(errno)) return 0 ;
+ s6dns_engine_recycle(dt) ;
+ dt->status = errno ;
+ return -1 ;
+}
+
+int s6dns_engine_init_r (s6dns_engine_t *dt, s6dns_ip46list_t const *servers, uint32 options, char const *q, unsigned int qlen, uint16 qtype, s6dns_debughook_t const *dbh, tain_t const *deadline, tain_t const *stamp)
+{
+ s6dns_message_header_t h = S6DNS_MESSAGE_HEADER_ZERO ;
+ if (!stralloc_ready(&dt->sa, qlen + 18)) return 0 ;
+ dt->deadline = *deadline ;
+ dt->localdeadline = *stamp ;
+ dt->querylen = qlen + 18 ;
+ dt->sa.len = dt->querylen ;
+ dt->servers = *servers ;
+ dt->debughook = dbh ;
+ dt->status = EAGAIN ;
+ dt->flagconnecting = dt->flagreading = dt->flagwriting = 0 ;
+ dt->flagstrict = !!(options & S6DNS_O_STRICT) ;
+ h.rd = !!(options & S6DNS_O_RECURSIVE) ;
+ h.counts.qd = 1 ;
+ uint16_pack_big(dt->sa.s, qlen + 16) ;
+ s6dns_message_header_pack(dt->sa.s + 2, &h) ;
+ byte_copy(dt->sa.s + 14, qlen, q) ;
+ uint16_pack_big(dt->sa.s + 14 + qlen, qtype) ;
+ uint16_pack_big(dt->sa.s + 16 + qlen, S6DNS_C_IN) ;
+ if (qlen > 496) dt->flagtcp = 1 ;
+ else
+ {
+ dt->flagtcp = 0 ;
+ dt->protostate = h.rd ;
+ }
+ if (!s6dns_engine_prepare(dt, stamp, dt->flagtcp))
+ {
+ s6dns_engine_recycle(dt) ;
+ return 0 ;
+ }
+ return 1 ;
+}