X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fnetwork%2Fres_msend.c;h=1e76886aa12277668a9979fadeb4a79b5cd76697;hb=51d4669fb97782f6a66606da852b5afd49a08001;hp=9adaea13b950fc34f95fc09353b1f867da6b7ed3;hpb=a636fd630f70da01665c5cfaf01b8a657ef6c2fe;p=musl

diff --git a/src/network/res_msend.c b/src/network/res_msend.c
index 9adaea13..1e76886a 100644
--- a/src/network/res_msend.c
+++ b/src/network/res_msend.c
@@ -1,5 +1,6 @@
 #include <sys/socket.h>
 #include <netinet/in.h>
+#include <netinet/tcp.h>
 #include <netdb.h>
 #include <arpa/inet.h>
 #include <stdint.h>
@@ -16,7 +17,9 @@
 
 static void cleanup(void *p)
 {
-	__syscall(SYS_close, (intptr_t)p);
+	struct pollfd *pfd = p;
+	for (int i=0; pfd[i].fd >= -1; i++)
+		if (pfd[i].fd >= 0) __syscall(SYS_close, pfd[i].fd);
 }
 
 static unsigned long mtime()
@@ -27,6 +30,51 @@ static unsigned long mtime()
 		+ ts.tv_nsec / 1000000;
 }
 
+static int start_tcp(struct pollfd *pfd, int family, const void *sa, socklen_t sl, const unsigned char *q, int ql)
+{
+	struct msghdr mh = {
+		.msg_name = (void *)sa,
+		.msg_namelen = sl,
+		.msg_iovlen = 2,
+		.msg_iov = (struct iovec [2]){
+			{ .iov_base = (uint8_t[]){ ql>>8, ql }, .iov_len = 2 },
+			{ .iov_base = (void *)q, .iov_len = ql } }
+	};
+	int r;
+	int fd = socket(family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+	pfd->fd = fd;
+	pfd->events = POLLOUT;
+	if (!setsockopt(fd, IPPROTO_TCP, TCP_FASTOPEN_CONNECT,
+	    &(int){1}, sizeof(int))) {
+		r = sendmsg(fd, &mh, MSG_FASTOPEN|MSG_NOSIGNAL);
+		if (r == ql+2) pfd->events = POLLIN;
+		if (r >= 0) return r;
+		if (errno == EINPROGRESS) return 0;
+	}
+	r = connect(fd, sa, sl);
+	if (!r || errno == EINPROGRESS) return 0;
+	close(fd);
+	pfd->fd = -1;
+	return -1;
+}
+
+static void step_mh(struct msghdr *mh, size_t n)
+{
+	/* Adjust iovec in msghdr to skip first n bytes. */
+	while (mh->msg_iovlen && n >= mh->msg_iov->iov_len) {
+		n -= mh->msg_iov->iov_len;
+		mh->msg_iov++;
+		mh->msg_iovlen--;
+	}
+	if (!mh->msg_iovlen) return;
+	mh->msg_iov->iov_base = (char *)mh->msg_iov->iov_base + n;
+	mh->msg_iov->iov_len -= n;
+}
+
+/* Internal contract for __res_msend[_rc]: asize must be >=512, nqueries
+ * must be sufficiently small to be safe as VLA size. In practice it's
+ * either 1 or 2, anyway. */
+
 int __res_msend_rc(int nqueries, const unsigned char *const *queries,
 	const int *qlens, unsigned char *const *answers, int *alens, int asize,
 	const struct resolvconf *conf)
@@ -44,7 +92,10 @@ int __res_msend_rc(int nqueries, const unsigned char *const *queries,
 	int next;
 	int i, j;
 	int cs;
-	struct pollfd pfd;
+	struct pollfd pfd[nqueries+2];
+	int qpos[nqueries], apos[nqueries];
+	unsigned char alen_buf[nqueries][2];
+	int r;
 	unsigned long t0, t1, t2;
 
 	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
@@ -92,7 +143,12 @@ int __res_msend_rc(int nqueries, const unsigned char *const *queries,
 	 * yield either no reply (indicated by zero length) or an answer
 	 * packet which is up to the caller to interpret. */
 
-	pthread_cleanup_push(cleanup, (void *)(intptr_t)fd);
+	for (i=0; i<nqueries; i++) pfd[i].fd = -1;
+	pfd[nqueries].fd = fd;
+	pfd[nqueries].events = POLLIN;
+	pfd[nqueries+1].fd = -2;
+
+	pthread_cleanup_push(cleanup, pfd);
 	pthread_setcancelstate(cs, 0);
 
 	/* Convert any IPv4 addresses in a mixed environment to v4-mapped */
@@ -112,14 +168,17 @@ int __res_msend_rc(int nqueries, const unsigned char *const *queries,
 
 	memset(alens, 0, sizeof *alens * nqueries);
 
-	pfd.fd = fd;
-	pfd.events = POLLIN;
 	retry_interval = timeout / attempts;
 	next = 0;
 	t0 = t2 = mtime();
 	t1 = t2 - retry_interval;
 
 	for (; t2-t0 < timeout; t2=mtime()) {
+		/* This is the loop exit condition: that all queries
+		 * have an accepted answer. */
+		for (i=0; i<nqueries && alens[i]>0; i++);
+		if (i==nqueries) break;
+
 		if (t2-t1 >= retry_interval) {
 			/* Query all configured namservers in parallel */
 			for (i=0; i<nqueries; i++)
@@ -133,9 +192,10 @@ int __res_msend_rc(int nqueries, const unsigned char *const *queries,
 		}
 
 		/* Wait for a response, or until time to retry */
-		if (poll(&pfd, 1, t1+retry_interval-t2) <= 0) continue;
+		if (poll(pfd, nqueries+1, t1+retry_interval-t2) <= 0) continue;
 
-		while ((rlen = recvfrom(fd, answers[next], asize, 0,
+		while (next < nqueries &&
+		  (rlen = recvfrom(fd, answers[next], asize, 0,
 		  (void *)&sa, (socklen_t[1]){sl})) >= 0) {
 
 			/* Ignore non-identifiable packets */
@@ -176,12 +236,72 @@ int __res_msend_rc(int nqueries, const unsigned char *const *queries,
 			else
 				memcpy(answers[i], answers[next], rlen);
 
-			if (next == nqueries) goto out;
+			/* Ignore further UDP if all slots full or TCP-mode */
+			if (next == nqueries) pfd[nqueries].events = 0;
+
+			/* If answer is truncated (TC bit), fallback to TCP */
+			if (answers[i][2] & 2) {
+				alens[i] = -1;
+				pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, 0);
+				r = start_tcp(pfd+i, family, ns+j, sl, queries[i], qlens[i]);
+				pthread_setcancelstate(cs, 0);
+				if (r >= 0) {
+					qpos[i] = r;
+					apos[i] = 0;
+				}
+				continue;
+			}
+		}
+
+		for (i=0; i<nqueries; i++) if (pfd[i].revents & POLLOUT) {
+			struct msghdr mh = {
+				.msg_iovlen = 2,
+				.msg_iov = (struct iovec [2]){
+					{ .iov_base = (uint8_t[]){ qlens[i]>>8, qlens[i] }, .iov_len = 2 },
+					{ .iov_base = (void *)queries[i], .iov_len = qlens[i] } }
+			};
+			step_mh(&mh, qpos[i]);
+			r = sendmsg(pfd[i].fd, &mh, MSG_NOSIGNAL);
+			if (r < 0) goto out;
+			qpos[i] += r;
+			if (qpos[i] == qlens[i]+2)
+				pfd[i].events = POLLIN;
+		}
+
+		for (i=0; i<nqueries; i++) if (pfd[i].revents & POLLIN) {
+			struct msghdr mh = {
+				.msg_iovlen = 2,
+				.msg_iov = (struct iovec [2]){
+					{ .iov_base = alen_buf[i], .iov_len = 2 },
+					{ .iov_base = answers[i], .iov_len = asize } }
+			};
+			step_mh(&mh, apos[i]);
+			r = recvmsg(pfd[i].fd, &mh, 0);
+			if (r < 0) goto out;
+			apos[i] += r;
+			if (apos[i] < 2) continue;
+			int alen = alen_buf[i][0]*256 + alen_buf[i][1];
+			if (alen < 13) goto out;
+			if (apos[i] < alen+2 && apos[i] < asize+2)
+				continue;
+			int rcode = answers[i][3] & 15;
+			if (rcode != 0 && rcode != 3)
+				goto out;
+
+			/* Storing the length here commits the accepted answer.
+			 * Immediately close TCP socket so as not to consume
+			 * resources we no longer need. */
+			alens[i] = alen;
+			__syscall(SYS_close, pfd[i].fd);
+			pfd[i].fd = -1;
 		}
 	}
 out:
 	pthread_cleanup_pop(1);
 
+	/* Disregard any incomplete TCP results */
+	for (i=0; i<nqueries; i++) if (alens[i]<0) alens[i] = 0;
+
 	return 0;
 }