I have written a small to test TCP/IP roundtrip times of the packets in
a proprietary protocol and while
compiling and running this server on different platforms (Windows
7/cygwin, UbuntuLinux, FreeBSD 8.0 Release), I found
that the server produces an error when the listening socket (on which
the accpet() is performed) is member of the select()
fd_set.
On the other platforms the program works without error, just under
FreeBSD I'm getting this "invalid argument" error.
Comments appreciated (despite comments about the error checking logic :)
Here is the code:
// testsrv.c
// gcc -o testsrv testsrv.c
//
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define USEDBUFSIZ 60
#define MAX_HOSTNAME 256
#define MAXFDS 256
#define CLRBUF memset(buf,0,sizeof(buf))
#define max(a,b)(((a) > (b)) ? (a) : (b))
static unsigned char buf[256];
int array_of_fds[MAXFDS];
static fd_set clientfds;
#define SOCKET int
void *memset(void *, int, size_t);
int enter (int);
int remov (int);
int invalidip (char *);
voidexit (int);
int getv (int, unsigned char *, int);
int getfds ();
int
main(int argc, char **argv)
{
int nfds;
static fd_set readfds;
SOCKET ListenSocket, newsockfd;
struct sockaddr_in cli_addr;
struct sockaddr_in service;
struct hostent *thisHost;
int bOptVal = 0;
int bOptLen = sizeof(int);
charhostname[256];
char *host_addr;
struct in_addr addr = {0};
char *ip;
u_short port;
int iResult = 0;
int i , n, m, clilen, dummy, connect = 0;
struct timeval tv;
//---
//Create a listening socket
ListenSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (ListenSocket == -1) {
perror("socket creation");
return 1;
} else
printf("ListenSocket=%d\n", ListenSocket);
//---
//Bind the socket to the local IP address
// and port 3210
port = 3210;
if (gethostname(hostname, 256))
perror("gethostname failed\n"), exit(3);
printf("%s\n", hostname), fflush(stdout);
thisHost = gethostbyname(hostname);
ip = inet_ntoa(*(struct in_addr *)(*thisHost->h_addr_list));
if (argc == 2) {
host_addr = argv[1];
service.sin_addr.s_addr = inet_addr(host_addr);
thisHost = gethostbyaddr((const char *)&service.sin_addr.s_addr,
sizeof(service.sin_addr.s_addr), AF_INET);
if (thisHost == 0)
printf("host unknown\n"), exit(3);
if (invalidip(host_addr))
printf("invalid IP\n"), exit(4);
} else {
service.sin_addr.s_addr = inet_addr(ip);
}
service.sin_port = htons(port);
service.sin_family = AF_INET;
iResult = bind(ListenSocket, (struct sockaddr *)&service,
sizeof(service));
if (iResult == -1) {
perror("bind");
shutdown(ListenSocket, SHUT_RDWR);
return 1;
}
listen(ListenSocket, SOMAXCONN);
printf("SOMAXCONN=%d %d\n", SOMAXCONN, FD_SETSIZE);
/* all sockets are put into an own array_of_fs */
/* in the while() loop below the FD_SET id used by looping through
the */
/* array_of_fds to fill the readfds array in the select() */
enter(ListenSocket);
/*
* Wait for connect
*/
tv.tv_sec = 0;
tv.tv_usec = 500; /* 5 seconds */
printf("Server %s listening on port %d\n", thisHost->h_name, port);
memset((void *)array_of_fds, 0, (size_t) MAXFDS *
sizeof(*array_of_fds));
nfds = ListenSocket + 1;
while (1) {
FD_ZERO(&readfds);
FD_SET(ListenSocket, &readfds);
for (i = 0; i < MAXFDS; i++) {
if (array_of_fds[i]) {
nfds = max(nfds, array_of_fds[i]) + 1;
FD_SET(array_of_fds[i], &readfds);
}
}
n = select(nfds, &readfds,
(fd_set *) NULL, /* not interested in write */
(fd_set *) NULL, /* ...or exceptions */
&tv);/* timeout */
switch (n) {
case 1:
clilen = sizeof(cli_addr);
/* first test if a new client has connected */
if (FD_ISSET(ListenSocket, &readfds)) {
newsockfd = accept(ListenSocket,
(struct sockaddr *)&cli_addr, &clilen);
if (enter(newsockfd)) /* socket of new connection is
entered*/
printf("\n%d.connect! ", ++connect), fflush(stdout);
else
printf("too many connections"), exit(1);
sprintf(buf, "ENTERED %d of %d", 1, 10);
send(newsockfd, buf, USEDBUFSIZ, 0); /* send to t
