Functionality only possible if recvfrom() is available.
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5ca692fc89
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2a6148716c
@ -429,8 +429,10 @@ static void read_udp_packets(ares_channel channel, fd_set *read_fds,
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int i;
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ssize_t count;
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unsigned char buf[PACKETSZ + 1];
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#ifdef HAVE_RECVFROM
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struct sockaddr_in from;
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socklen_t fromlen;
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#endif
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if(!read_fds && (read_fd == ARES_SOCKET_BAD))
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/* no possible action */
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@ -464,23 +466,24 @@ static void read_udp_packets(ares_channel channel, fd_set *read_fds,
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/* To reduce event loop overhead, read and process as many
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* packets as we can. */
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do {
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/* Must memset 'from' to 0 as recvfrom() on some systems may
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* not use 'from' at all if it doesn't support receiving the
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* source address of the response */
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memset(&from, 0, sizeof(from));
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#ifdef HAVE_RECVFROM
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fromlen = sizeof(from);
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count = (ssize_t)recvfrom(server->udp_socket, (void *)buf, sizeof(buf),
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0, (struct sockaddr *)&from, &fromlen);
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#else
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count = sread(server->udp_socket, buf, sizeof(buf));
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#endif
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if (count == -1 && try_again(SOCKERRNO))
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continue;
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else if (count <= 0)
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handle_error(channel, i, now);
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else if (fromlen && from.sin_addr.s_addr != 0 &&
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from.sin_addr.s_addr != server->addr.s_addr)
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#ifdef HAVE_RECVFROM
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else if (from.sin_addr.s_addr != server->addr.s_addr)
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/* Address response came from did not match the address
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* we sent the request to. Someone may be attempting
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* to perform a cache poisoning attack */
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break;
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#endif
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else
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process_answer(channel, buf, (int)count, i, 0, now);
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} while (count > 0);
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