adapt res_msend DNS query core for working with multiple sockets

this is groundwork for TCP fallback support, but does not itself
change behavior in any way.

diff --git a/src/network/res_msend.c b/src/network/res_msend.c
index 9adaea1..98e6d8a 100644 (file)
--- a/src/network/res_msend.c
+++ b/src/network/res_msend.c
@@ -16,7 +16,9 @@
 
 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()
@@ -44,7 +46,7 @@ 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];
        unsigned long t0, t1, t2;
 
        pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
@@ -92,7 +94,12 @@ 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 */
@@ -112,8 +119,6 @@ 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();
@@ -133,7 +138,7 @@ 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,
                  (void *)&sa, (socklen_t[1]){sl})) >= 0) {