void main_loop() {
int res;
fd_set fdr;
fd_set fdw;
// see if there are any connections to accept or read / write from
FD_ZERO(&fdr);
FD_ZERO(&fdw);
FD_SET(server.fd, &fdr);
FD_SET(server.fd, &fdw);
#if !TEST_DGRAM
if (client.fd) FD_SET(client.fd, &fdr);
if (client.fd) FD_SET(client.fd, &fdw);
#endif
res = select(64, &fdr, &fdw, NULL, NULL);
if (res == -1) {
perror("select failed");
exit(EXIT_SUCCESS);
}
#if !TEST_DGRAM
// for TCP sockets, we may need to accept a connection
if (FD_ISSET(server.fd, &fdr)) {
#if TEST_ACCEPT_ADDR
// Do an accept with non-NULL addr and addlen parameters. This tests a fix to a bug in the implementation of
// accept which had a parameter "addrp" but used "addr" internally if addrp was set - giving a ReferenceError.
struct sockaddr_in addr = {0};
addr.sin_family = AF_INET;
socklen_t addrlen = sizeof(addr);
client.fd = accept(server.fd, (struct sockaddr *) &addr, &addrlen);
#else
client.fd = accept(server.fd, NULL, NULL);
#endif
assert(client.fd != -1);
}
#endif
#if !TEST_DGRAM
int fd = client.fd;
#else
int fd = server.fd;
#endif
if (client.state == MSG_READ) {
if (!FD_ISSET(fd, &fdr)) {
return;
}
socklen_t addrlen = sizeof(client.addr);
res = do_msg_read(fd, &client.msg, client.read, 0, (struct sockaddr *)&client.addr, &addrlen);
if (res == -1) {
return;
} else if (res == 0) {
// client disconnected
memset(&client, 0, sizeof(client_t));
return;
}
client.read += res;
// once we've read the entire message, echo it back
if (client.read >= client.msg.length) {
client.read = 0;
client.state = MSG_WRITE;
}
}
if (client.state == MSG_WRITE) {
if (!FD_ISSET(fd, &fdw)) {
return;
}
res = do_msg_write(fd, &client.msg, client.wrote, 0, (struct sockaddr *)&client.addr, sizeof(client.addr));
if (res == -1) {
return;
} else if (res == 0) {
// client disconnected
memset(&client, 0, sizeof(client_t));
return;
}
client.wrote += res;
if (client.wrote >= client.msg.length) {
client.wrote = 0;
client.state = MSG_READ;
#if CLOSE_CLIENT_AFTER_ECHO
close(client.fd);
memset(&client, 0, sizeof(client_t));
#endif
}
}
}
void main_loop() {
static char out[1024*2];
static int pos = 0;
fd_set fdr;
fd_set fdw;
int res;
// make sure that server.fd is ready to read / write
FD_ZERO(&fdr);
FD_ZERO(&fdw);
FD_SET(server.fd, &fdr);
FD_SET(server.fd, &fdw);
res = select(64, &fdr, &fdw, NULL, NULL);
if (res == -1) {
perror("select failed");
finish(EXIT_FAILURE);
}
if (server.state == MSG_READ) {
if (!FD_ISSET(server.fd, &fdr)) {
return;
}
#if !TEST_DGRAM
// as a test, confirm with ioctl that we have data available
// after selecting
int available;
res = ioctl(server.fd, FIONREAD, &available);
assert(res != -1);
assert(available);
#endif
res = do_msg_read(server.fd, &server.msg, echo_read, 0, NULL, NULL);
if (res == -1) {
return;
} else if (res == 0) {
perror("server closed");
finish(EXIT_FAILURE);
}
echo_read += res;
// once we've read the entire message, validate it
if (echo_read >= server.msg.length) {
assert(!strcmp(server.msg.buffer, MESSAGE));
finish(EXIT_SUCCESS);
}
}
if (server.state == MSG_WRITE) {
if (!FD_ISSET(server.fd, &fdw)) {
return;
}
res = do_msg_write(server.fd, &echo_msg, echo_wrote, 0, NULL, 0);
if (res == -1) {
return;
} else if (res == 0) {
perror("server closed");
finish(EXIT_FAILURE);
}
echo_wrote += res;
// once we're done writing the message, read it back
if (echo_wrote >= echo_msg.length) {
server.state = MSG_READ;
}
}
}
void main_loop() {
static int state = 0;
static int readPos = 0;
static int writePos = 0;
int selectRes;
ssize_t transferAmount;
fd_set sett;
switch (state) {
case 0:
// writing 10 bytes to the server
// since the socket in the read file descriptors has no available data,
// select should tell us 0 handles are ready
FD_ZERO(&sett);
FD_SET(sockfd, &sett);
selectRes = select(64, &sett, NULL, NULL, NULL);
if (selectRes != 0) {
printf("case 0: read select != 0 (%d)\n", selectRes);
finish(EXIT_FAILURE);
}
// the socket in the write file descriptors has to result in either a 0 or 1
// the connection either is setting up or is established and writing is possible
FD_ZERO(&sett);
FD_SET(sockfd, &sett);
selectRes = select(64, NULL, &sett, NULL, NULL);
if (selectRes == -1) {
printf("case 0: write select == -1\n");
finish(EXIT_FAILURE);
} else if (selectRes == 0) {
return;
}
// send a single byte
transferAmount = do_msg_write(sockfd, &writemsg, writePos, 1, NULL, 0);
if (transferAmount != -1) writePos += transferAmount;
// after 10 bytes switch to next state
if (writePos >= writemsg.length) {
state = 1;
}
break;
case 1:
// wait until we can read one byte to make sure the server
// has sent the data and then closed the connection
FD_ZERO(&sett);
FD_SET(sockfd, &sett);
selectRes = select(64, &sett, NULL, NULL, NULL);
if (selectRes == -1) {
printf("case 1: read selectRes == -1\n");
finish(EXIT_FAILURE);
} else if (selectRes == 0) {
return;
}
// read a single byte
transferAmount = do_msg_read(sockfd, &readmsg, readPos, 1, NULL, NULL);
if (transferAmount == 0) {
perror("server closed");
finish(EXIT_FAILURE);
} else if (transferAmount != -1) {
readPos += transferAmount;
}
// if successfully reading 1 byte, switch to next state
if (readPos >= 1) {
state = 2;
}
break;
case 2:
// calling select with the socket in the write file descriptors should
// succeed, but the socket should not set in the set.
FD_ZERO(&sett);
FD_SET(sockfd, &sett);
selectRes = select(64, NULL, &sett, NULL, NULL);
if (selectRes != 0 || FD_ISSET(sockfd, &sett)) {
printf("case 2: write selectRes != 0 || FD_ISSET(sockfd, &sett)\n");
finish(EXIT_FAILURE);
}
// calling select with the socket in the read file descriptors
// has to succeed because there is still data in the inQueue
FD_ZERO(&sett);
FD_SET(sockfd, &sett);
selectRes = select(64, &sett, NULL, NULL, NULL);
if (selectRes != 1) {
printf("case 2: read selectRes != 1\n");
finish(EXIT_FAILURE);
} else if (selectRes == 0) {
return;
}
// read a single byte
transferAmount = do_msg_read(sockfd, &readmsg, readPos, 1, NULL, NULL);
if (transferAmount == 0) {
perror("server closed");
finish(EXIT_FAILURE);
} else if (transferAmount != -1) {
readPos += transferAmount;
}
// with 10 bytes read the inQueue is empty => switch state
if (readPos >= readmsg.length) {
state = 3;
}
break;
case 3:
// calling select with the socket in the read file descriptors
// should succeed
FD_ZERO(&sett);
FD_SET(sockfd, &sett);
selectRes = select(64, &sett, NULL, NULL, NULL);
if (selectRes != 1) {
printf("case 3: read selectRes != 1\n");
finish(EXIT_FAILURE);
}
// but recv should return 0 signaling the remote
// end has closed the connection.
transferAmount = do_msg_read(sockfd, &readmsg, readPos, 0, NULL, NULL);
if (transferAmount) {
printf("case 3: read != 0\n");
finish(EXIT_FAILURE);
}
// report back success, the 266 is just an arbitrary value without
// deeper meaning
finish(266);
break;
default:
printf("Impossible state!\n");
finish(EXIT_FAILURE);
break;
}
return;
}
