From 7f175ccbc38c0de2423a9554f8ee1663431845d9 Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Thu, 16 Aug 2007 18:27:47 +0000 Subject: [PATCH] add comments regarding SO_REUSEADDR --- include/libbb.h | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/include/libbb.h b/include/libbb.h index 7b456a9fa..912505026 100644 --- a/include/libbb.h +++ b/include/libbb.h @@ -282,6 +282,13 @@ void xlisten(int s, int backlog); void xconnect(int s, const struct sockaddr *s_addr, socklen_t addrlen); ssize_t xsendto(int s, const void *buf, size_t len, const struct sockaddr *to, socklen_t tolen); +/* SO_REUSEADDR allows a server to rebind to an address that is already + * "in use" by old connections to e.g. previous server instance which is + * killed or crashed. Without it bind will fail until all such connections + * time out. Linux does not allow multiple live binds on same ip:port + * regardless of SO_REUSEADDR (unlike some other flavors of Unix). + * Turn it on before you call bind(). */ +//TODO: it seems like in Linux this never fails. Change to void, eliminate error checks int setsockopt_reuseaddr(int fd); int setsockopt_broadcast(int fd); /* NB: returns port in host byte order */ @@ -318,6 +325,7 @@ int xsocket_stream(len_and_sockaddr **lsap); * numeric IP ("N.N.N.N") or numeric IPv6 address, * and can have ":PORT" suffix (for IPv6 use "[X:X:...:X]:PORT"). * Only if there is no suffix, port argument is used */ +/* NB: these set SO_REUSEADDR before bind */ int create_and_bind_stream_or_die(const char *bindaddr, int port); int create_and_bind_dgram_or_die(const char *bindaddr, int port); /* Create client TCP socket connected to peer:port. Peer cannot be NULL. @@ -345,7 +353,7 @@ len_and_sockaddr* xhost_and_af2sockaddr(const char *host, int port, sa_family_t #define host_and_af2sockaddr(host, port, af) ((void)(af), host2sockaddr((host), (port))) #define xhost_and_af2sockaddr(host, port, af) ((void)(af), xhost2sockaddr((host), (port))) #endif -/* Assign sin[6]_port member if the socket is of corresponding type, +/* Assign sin[6]_port member if the socket is an AF_INET[6] one, * otherwise no-op. Useful for ftp. * NB: does NOT do htons() internally, just direct assignment. */ void set_nport(len_and_sockaddr *lsa, unsigned port); -- 2.25.1