Hello, I was examining how many TCP and UDP ports are assigned for bind(2) with addr.sin_port = htons(0). I found strange behavior with 2.6.12-1.1447_FC4 kernel. In the case of socket(AF_INET, SOCK_STREAM, 0), it returned error when exhausted local port range during search as they are described in the source code. http://lxr.linux.no/source/net/ipv4/tcp_ipv4.c#L218 http://lxr.linux.no/source/net/ipv4/tcp_ipv4.c?v=2.4.28#L218 But in the case of socket(AF_INET, SOCK_DGRAM, 0), it doesn't seem to return error when exhausted local port range during search. http://lxr.linux.no/source/net/ipv4/udp.c#L130 http://lxr.linux.no/source/net/ipv4/udp.c?v=2.4.28#L116 Running the following program needs too long busy time (I think it has fallen into infinite busy loop) with my FC4 environment. Does automatic local port assignment for UDP MUST NOT FAIL? Or is this a bug? Regards. --- bindtest.c --- #include <stdio.h> #include <string.h> #include <unistd.h> #include <sys/socket.h> #include <netinet/in.h> #include <errno.h> int main(int argc, char *argv[]) { int i; for (i = 0; i < 128; i++) { switch (fork()) { case 0: for (i = 0; i < 512; i++) { int fd = socket(AF_INET, SOCK_DGRAM, 0); struct sockaddr_in addr; memset(&addr, 0, sizeof(addr)); addr.sin_family = AF_INET; addr.sin_addr.s_addr = htonl(INADDR_ANY); addr.sin_port = htons(0); if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) == 0) { socklen_t size = sizeof(addr); getsockname(fd, (struct sockaddr *) &addr, &size); printf("%05d\n", ntohs(addr.sin_port)); fflush(stdout); } } while (1) sleep(100); } } while (1) sleep(100); return 0; } -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
