diff options
author | Rich Felker <dalias@aerifal.cx> | 2011-09-21 23:17:45 -0400 |
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committer | Rich Felker <dalias@aerifal.cx> | 2011-09-21 23:17:45 -0400 |
commit | bf027ca5e0c7bc0b90e84dcbb1d7cbea6ed1e3ef (patch) | |
tree | 09873e1c784b4ac272accec695153bb7f6a2eb6b /src/network/__dns.c | |
parent | 81a5577a860b1d320239a84c84266e4d7045f450 (diff) | |
download | musl-bf027ca5e0c7bc0b90e84dcbb1d7cbea6ed1e3ef.tar.gz |
use poll rather than select in dns lookups (also clock_gettime)
if the file descriptor resource limit has been increased past
FD_SETSIZE, this is actually a security issue; we could write past the
end of the fd_set object. using poll makes it a non-issue, and
simplifies the code at the same time.
also, use clock_gettime instead of gettimeofday, for reduced bloat
and better entropy.
Diffstat (limited to 'src/network/__dns.c')
-rw-r--r-- | src/network/__dns.c | 22 |
1 files changed, 10 insertions, 12 deletions
diff --git a/src/network/__dns.c b/src/network/__dns.c index b3c876f3..a5458b51 100644 --- a/src/network/__dns.c +++ b/src/network/__dns.c @@ -5,8 +5,7 @@ #include <limits.h> #include <string.h> #include <sys/socket.h> -#include <sys/select.h> -#include <sys/time.h> +#include <poll.h> #include <netinet/in.h> #include <time.h> #include <ctype.h> @@ -16,7 +15,7 @@ #include "stdio_impl.h" #define TIMEOUT 5 -#define RETRY 1 +#define RETRY 1000 #define PACKET_MAX 512 #define PTR_MAX (64 + sizeof ".in-addr.arpa") @@ -40,8 +39,8 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt) int got = 0, failed = 0; int errcode = EAI_AGAIN; int i, j; - struct timeval tv; - fd_set fds; + struct timespec ts; + struct pollfd pfd; int id; int cs; @@ -58,8 +57,8 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt) ql = i+4; /* Make a reasonably unpredictable id */ - gettimeofday(&tv, 0); - id = tv.tv_usec + tv.tv_usec/256 & 0xffff; + clock_gettime(CLOCK_REALTIME, &ts); + id = ts.tv_nsec + ts.tv_nsec/65536UL & 0xffff; /* Get nameservers from resolv.conf, fallback to localhost */ f = __fopen_rb_ca("/etc/resolv.conf", &_f, _buf, sizeof _buf); @@ -94,6 +93,9 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt) /* Nonblocking to work around Linux UDP select bug */ fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) | O_NONBLOCK); + pfd.fd = fd; + pfd.events = POLLIN; + /* Loop until we timeout; break early on success */ for (; time(0)-t0 < TIMEOUT; ) { @@ -106,11 +108,7 @@ int __dns_doqueries(unsigned char *dest, const char *name, int *rr, int rrcnt) } /* Wait for a response, or until time to retry */ - FD_ZERO(&fds); - FD_SET(fd, &fds); - tv.tv_sec = RETRY; - tv.tv_usec = 0; - if (select(fd+1, &fds, 0, 0, &tv) <= 0) continue; + if (poll(&pfd, 1, RETRY) <= 0) continue; /* Process any and all replies */ while (got+failed < rrcnt && (rlen = recvfrom(fd, r, 512, 0, |