added ares_process_fd() to allow applications to ask for processing on
specific sockets and thus avoiding select() and associated functions/macros. This function will be used by upcoming libcurl releases for this very reason. It also made me export the ares_socket_t type in the public ares.h header file, since ares_process_fd() uses that type for two of the arguments.
This commit is contained in:
Daniel Stenberg
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Коммит
670273968c
10
ares/CHANGES
10
ares/CHANGES
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@ -1,6 +1,16 @@
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Changelog for the c-ares project
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* May 30 2007
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- Daniel S added ares_process_fd() to allow applications to ask for processing
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on specific sockets and thus avoiding select() and associated
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functions/macros. This function will be used by upcoming libcurl releases
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for this very reason. It also made me export the ares_socket_t type in the
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public ares.h header file, since ares_process_fd() uses that type for two of
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the arguments.
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* May 25 2007
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- Ravi Pratap fixed a flaw in the init_by_resolv_conf() function for windows
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that could cause it to return a bad return code.
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18
ares/ares.h
18
ares/ares.h
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@ -136,6 +136,22 @@ extern "C" {
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#define ARES_GETSOCK_WRITABLE(bits,num) (bits & (1 << ((num) + \
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ARES_GETSOCK_MAXNUM)))
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/*
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* Typedef our socket type
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*/
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#ifndef ares_socket_typedef
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#ifdef WIN32
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typedef SOCKET ares_socket_t;
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#define ARES_SOCKET_BAD INVALID_SOCKET
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#else
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typedef int ares_socket_t;
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#define ARES_SOCKET_BAD -1
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#endif
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#define ares_socket_typedef
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#endif /* ares_socket_typedef */
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#ifdef WIN32
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typedef void (*ares_sock_state_cb)(void *data,
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SOCKET socket,
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@ -200,6 +216,8 @@ int ares_getsock(ares_channel channel, int *socks, int numsocks);
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struct timeval *ares_timeout(ares_channel channel, struct timeval *maxtv,
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struct timeval *tv);
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void ares_process(ares_channel channel, fd_set *read_fds, fd_set *write_fds);
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void ares_process_fd(ares_channel channel, ares_socket_t read_fd,
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ares_socket_t write_fd);
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int ares_mkquery(const char *name, int dnsclass, int type, unsigned short id,
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int rd, unsigned char **buf, int *buflen);
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@ -24,16 +24,16 @@ ares_process \- Process events for name resolution
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.B void ares_process(ares_channel \fIchannel\fP, fd_set *\fIread_fds\fP,
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.B fd_set *\fIwrite_fds\fP)
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.fi
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.PP
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.B void ares_process_fd(ares_channel \fIchannel\fP,
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.B ares_socket_t \fIread_fd\fP,
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.B ares_socket_t \fIwrite_fd\fP)
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.fi
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.SH DESCRIPTION
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The
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.B ares_process
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function handles input/output events and timeouts associated with
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queries pending on the name service channel identified by
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The \fBares_process(3)\fP function handles input/output events and timeouts
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associated with queries pending on the name service channel identified by
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.IR channel .
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The file descriptor sets pointed to by
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.I read_fds
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and
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.I write_fds
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The file descriptor sets pointed to by \fIread_fds\fP and \fIwrite_fds\fP
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should have file descriptors set in them according to whether the file
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descriptors specified by \fIares_fds(3)\fP are ready for reading and writing.
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(The easiest way to determine this information is to invoke
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@ -44,6 +44,11 @@ The
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.B ares_process
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function will invoke callbacks for pending queries if they complete
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successfully or fail.
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\fBares_process_fd(3)\fP works the same way but acts and operates only on the
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specific file descriptors (sockets) you pass in to the function. Use
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ARES_SOCKET_BAD for "no action". This function is of course provided to allow
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users of c-ares to void select() in their applications and within c-ares.
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.SS EXAMPLE
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The following code fragment waits for all pending queries on a channel
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to complete:
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@ -56,10 +56,11 @@
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static int try_again(int errnum);
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static void write_tcp_data(ares_channel channel, fd_set *write_fds,
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time_t now);
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static void read_tcp_data(ares_channel channel, fd_set *read_fds, time_t now);
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ares_socket_t write_fd, time_t now);
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static void read_tcp_data(ares_channel channel, fd_set *read_fds,
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ares_socket_t read_fd, time_t now);
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static void read_udp_packets(ares_channel channel, fd_set *read_fds,
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time_t now);
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ares_socket_t read_fd, time_t now);
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static void process_timeouts(ares_channel channel, time_t now);
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static void process_answer(ares_channel channel, unsigned char *abuf,
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int alen, int whichserver, int tcp, int now);
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@ -80,12 +81,30 @@ void ares_process(ares_channel channel, fd_set *read_fds, fd_set *write_fds)
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time_t now;
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time(&now);
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write_tcp_data(channel, write_fds, now);
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read_tcp_data(channel, read_fds, now);
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read_udp_packets(channel, read_fds, now);
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write_tcp_data(channel, write_fds, ARES_SOCKET_BAD, now);
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read_tcp_data(channel, read_fds, ARES_SOCKET_BAD, now);
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read_udp_packets(channel, read_fds, ARES_SOCKET_BAD, now);
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process_timeouts(channel, now);
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}
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/* Something interesting happened on the wire, or there was a timeout.
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* See what's up and respond accordingly.
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*/
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void ares_process_fd(ares_channel channel,
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ares_socket_t read_fd, /* use ARES_SOCKET_BAD or valid
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file descriptors */
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ares_socket_t write_fd)
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{
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time_t now;
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time(&now);
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write_tcp_data(channel, NULL, write_fd, now);
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read_tcp_data(channel, NULL, read_fd, now);
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read_udp_packets(channel, NULL, read_fd, now);
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process_timeouts(channel, now);
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}
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/* Return 1 if the specified error number describes a readiness error, or 0
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* otherwise. This is mostly for HP-UX, which could return EAGAIN or
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* EWOULDBLOCK. See this man page
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@ -114,7 +133,10 @@ static int try_again(int errnum)
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/* If any TCP sockets select true for writing, write out queued data
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* we have for them.
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*/
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static void write_tcp_data(ares_channel channel, fd_set *write_fds, time_t now)
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static void write_tcp_data(ares_channel channel,
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fd_set *write_fds,
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ares_socket_t write_fd,
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time_t now)
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{
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struct server_state *server;
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struct send_request *sendreq;
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@ -124,14 +146,27 @@ static void write_tcp_data(ares_channel channel, fd_set *write_fds, time_t now)
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ssize_t wcount;
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size_t n;
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if(!write_fds && (write_fd == ARES_SOCKET_BAD))
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/* no possible action */
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return;
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for (i = 0; i < channel->nservers; i++)
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{
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/* Make sure server has data to send and is selected in write_fds. */
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/* Make sure server has data to send and is selected in write_fds or
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write_fd. */
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server = &channel->servers[i];
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if (!server->qhead || server->tcp_socket == ARES_SOCKET_BAD
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|| !FD_ISSET(server->tcp_socket, write_fds))
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if (!server->qhead || server->tcp_socket == ARES_SOCKET_BAD)
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continue;
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if(write_fds) {
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if(!FD_ISSET(server->tcp_socket, write_fds))
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continue;
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}
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else {
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if(server->tcp_socket != write_fd)
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continue;
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}
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/* Count the number of send queue items. */
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n = 0;
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for (sendreq = server->qhead; sendreq; sendreq = sendreq->next)
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@ -218,20 +253,33 @@ static void write_tcp_data(ares_channel channel, fd_set *write_fds, time_t now)
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* allocate a buffer if we finish reading the length word, and process
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* a packet if we finish reading one.
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*/
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static void read_tcp_data(ares_channel channel, fd_set *read_fds, time_t now)
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static void read_tcp_data(ares_channel channel, fd_set *read_fds,
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ares_socket_t read_fd, time_t now)
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{
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struct server_state *server;
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int i;
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ssize_t count;
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if(!read_fds && (read_fd == ARES_SOCKET_BAD))
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/* no possible action */
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return;
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for (i = 0; i < channel->nservers; i++)
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{
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/* Make sure the server has a socket and is selected in read_fds. */
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server = &channel->servers[i];
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if (server->tcp_socket == ARES_SOCKET_BAD ||
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!FD_ISSET(server->tcp_socket, read_fds))
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if (server->tcp_socket == ARES_SOCKET_BAD)
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continue;
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if(read_fds) {
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if(!FD_ISSET(server->tcp_socket, read_fds))
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continue;
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}
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else {
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if(server->tcp_socket != read_fd)
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continue;
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}
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if (server->tcp_lenbuf_pos != 2)
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{
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/* We haven't yet read a length word, so read that (or
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@ -294,22 +342,34 @@ static void read_tcp_data(ares_channel channel, fd_set *read_fds, time_t now)
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/* If any UDP sockets select true for reading, process them. */
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static void read_udp_packets(ares_channel channel, fd_set *read_fds,
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time_t now)
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ares_socket_t read_fd, time_t now)
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{
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struct server_state *server;
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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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if(!read_fds && (read_fd == ARES_SOCKET_BAD))
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/* no possible action */
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return;
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for (i = 0; i < channel->nservers; i++)
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{
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/* Make sure the server has a socket and is selected in read_fds. */
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server = &channel->servers[i];
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if (server->udp_socket == ARES_SOCKET_BAD ||
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!FD_ISSET(server->udp_socket, read_fds))
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if (server->udp_socket == ARES_SOCKET_BAD)
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continue;
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if(read_fds) {
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if(!FD_ISSET(server->udp_socket, read_fds))
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continue;
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}
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else {
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if(server->udp_socket != read_fd)
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continue;
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}
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count = sread(server->udp_socket, buf, sizeof(buf));
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if (count == -1 && try_again(SOCKERRNO))
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continue;
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14
ares/setup.h
14
ares/setup.h
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@ -3,7 +3,7 @@
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/* $Id$ */
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/* Copyright (C) 2004 - 2005 by Daniel Stenberg et al
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/* Copyright (C) 2004 - 2007 by Daniel Stenberg et al
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*
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* Permission to use, copy, modify, and distribute this software and its
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* documentation for any purpose and without fee is hereby granted, provided
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@ -117,18 +117,6 @@
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#undef VERSION
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#undef PACKAGE
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/*
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* Typedef our socket type
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*/
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#ifdef USE_WINSOCK
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typedef SOCKET ares_socket_t;
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#define ARES_SOCKET_BAD INVALID_SOCKET
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#else
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typedef int ares_socket_t;
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#define ARES_SOCKET_BAD -1
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#endif
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/*
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* Assume a few thing unless they're set by configure
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*/
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