make dns lookups (and thus getaddrinfo) cancellable

diff --git a/src/network/__dns.c b/src/network/__dns.c
index a5458b5..8cd7d5d 100644 (file)
--- a/src/network/__dns.c
+++ b/src/network/__dns.c
@@ -19,6 +19,11 @@
 #define PACKET_MAX 512
 #define PTR_MAX (64 + sizeof ".in-addr.arpa")
 
+static void cleanup(void *p)
+{
+       close((intptr_t)p);
+}
+
 int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt)
 {
        time_t t0 = time(0);
@@ -44,6 +49,8 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt)
        int id;
        int cs;
 
+       pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
+
        /* Construct query template - RR and ID will be filled later */
        if (strlen(name)-1 >= 254U) return EAI_NONAME;
        q[2] = q[5] = 1;
@@ -81,8 +88,6 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt)
                sl = sizeof sa.sin;
        }
 
-       pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
-
        /* Get local address and open/bind a socket */
        sa.sin.sin_family = family;
        fd = socket(family, SOCK_DGRAM, 0);
@@ -96,6 +101,9 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt)
        pfd.fd = fd;
        pfd.events = POLLIN;
 
+       pthread_cleanup_push(cleanup, (void *)(intptr_t)fd);
+       pthread_setcancelstate(cs, 0);
+
        /* Loop until we timeout; break early on success */
        for (; time(0)-t0 < TIMEOUT; ) {
 
@@ -143,8 +151,7 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt)
                if (got+failed == rrcnt) break;
        }
 out:
-       close(fd);
-       pthread_setcancelstate(cs, 0);
+       pthread_cleanup_pop(1);
 
        /* Return the number of results, or an error code if none */
        if (got) return got;