#include <sys/socket.h>
#include <netinet/in.h>
+#include <netinet/tcp.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <stdint.h>
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()
+ 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)
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);
timeout = 1000*conf->timeout;
attempts = conf->attempts;
- nns = conf->nns;
for (nns=0; nns<conf->nns; nns++) {
const struct address *iplit = &conf->ns[nns];
if (iplit->family == AF_INET) {
}
/* Get local address and open/bind a socket */
- sa.sin.sin_family = family;
fd = socket(family, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
/* Handle case where system lacks IPv6 support */
if (fd < 0 && family == AF_INET6 && errno == EAFNOSUPPORT) {
+ for (i=0; i<nns && conf->ns[nns].family == AF_INET6; i++);
+ if (i==nns) {
+ pthread_setcancelstate(cs, 0);
+ return -1;
+ }
fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
family = AF_INET;
+ sl = sizeof sa.sin;
+ }
+ sa.sin.sin_family = family;
+ if (fd < 0 || bind(fd, (void *)&sa, sl) < 0) {
+ if (fd >= 0) close(fd);
+ pthread_setcancelstate(cs, 0);
+ return -1;
}
- if (fd < 0 || bind(fd, (void *)&sa, sl) < 0) return -1;
/* Past this point, there are no errors. Each individual query will
* 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 */
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++)
}
/* 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 */
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;
}
projects / musl / blobdiff