by When I test in Linux 2.4.18-14debug(Redhat 8.0), only 10 or 11 datagrams
can be queued on a unix domain socket(datagram)'s receive buffer. If a
sender tries to send more datagrams, it blocks(in a blocking sento) or
returns error(in a non-blocking sendto). That doesn't make sense, because
each message is 10 bytes long and receive buffer size is 128KB. Is there any
solution?
----> dg_serv.c
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <errno.h>
#define MAXLINE 1024
int
main(int argc, char **argv)
{
int sockfd, clilen, rcvbufsize, len;
struct sockaddr_un cliaddr, servaddr;
char recvline[MAXLINE + 1];
char UNIXDG_PATH[30]="unix_sock_dgram";
sockfd = socket(AF_LOCAL, SOCK_DGRAM, 0);
unlink(UNIXDG_PATH);
bzero(&servaddr, sizeof(servaddr));
servaddr.sun_family = AF_LOCAL;
strcpy(servaddr.sun_path, UNIXDG_PATH);
bind(sockfd, (struct sockaddr*) &servaddr, sizeof(servaddr));
rcvbufsize = 256*1024; // when i tested, 128KB is max size
len = sizeof(rcvbufsize);
setsockopt( sockfd, SOL_SOCKET, SO_RCVBUF, &rcvbufsize, len);
getsockopt( sockfd, SOL_SOCKET, SO_RCVBUF, &rcvbufsize, &len);
printf("recv buffer size = %d\n", rcvbufsize);
clilen = sizeof(cliaddr);
while (1) {
int n;
getchar();
while( (n = recvfrom(sockfd, recvline, MAXLINE, MSG_DONTWAIT,
(struct sockaddr*) &cliaddr, &clilen ))>0 ) {
recvline[n]='\0';
printf("Received :%s", recvline);
}
}
----> dg_cli.cQuote:}
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <errno.h>
#define MAXLINE 1024
int
main(int argc, char **argv)
{
int sockfd, count=0;
struct sockaddr_un cliaddr, servaddr;
char UNIXDG_PATH[30]="unix_sock_dgram";
sockfd = socket(AF_LOCAL, SOCK_DGRAM, 0);
bzero(&cliaddr, sizeof(cliaddr)); /* bind an address for us */
cliaddr.sun_family = AF_LOCAL;
strcpy(cliaddr.sun_path, tmpnam(NULL));
bind(sockfd, (struct sockaddr*) &cliaddr, sizeof(cliaddr));
bzero(&servaddr, sizeof(servaddr)); /* fill in server's address */
servaddr.sun_family = AF_LOCAL;
strcpy(servaddr.sun_path, UNIXDG_PATH);
while (1) {
char sendline[MAXLINE];
int retval;
sprintf( sendline, "Message %d\n" , count);
retval = sendto(sockfd, sendline, strlen(sendline), MSG_DONTWAIT,
(struct sockaddr*) &servaddr, sizeof(servaddr) );
printf("called sendto() with %s", sendline);
printf("return value = %d, errno = %d\n",retval,errno);
sleep(1);
count += 1;
}
Quote:}