Re: [PATCH 3/3] tcp, udp: Make {tcp,udp}_listen() return socket fds

On Mon, 5 Jan 2026 19:28:50 +1100 David Gibson wrote:

{tcp,udp}_listen() currently return 0 on success, rather than the socket fd they created. Historically, that was because these functions could sometimes create multiple sockets. We've now refactored things to avoid that, so it makes more sense for them to return the socket on success.

Signed-off-by: David Gibson --- conf.c | 14 +++++++------- tcp.c | 7 ++----- udp.c | 4 ++-- 3 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/conf.c b/conf.c index cc3c20a9..5db49653 100644 --- a/conf.c +++ b/conf.c @@ -149,7 +149,7 @@ static void conf_ports_range_except(const struct ctx *c, char optname, { bool bound_one = false; unsigned i; - int ret; + int fd;

if (first == 0) { die("Can't forward port 0 for option '-%c %s'", @@ -185,23 +185,23 @@ static void conf_ports_range_except(const struct ctx *c, char optname, fwd->delta[i] = to - first;

if (optname == 't') - ret = tcp_listen(c, PIF_HOST, addr, ifname, i); + fd = tcp_listen(c, PIF_HOST, addr, ifname, i); else if (optname == 'u') - ret = udp_listen(c, PIF_HOST, addr, ifname, i); + fd = udp_listen(c, PIF_HOST, addr, ifname, i); else /* No way to check in advance for -T and -U */ - ret = 0; + fd = 0;

- if (ret == -ENFILE || ret == -EMFILE) { + if (fd == -ENFILE || fd == -EMFILE) { die("Can't open enough sockets for port specifier: %s", optarg); }

- if (!ret) { + if (fd >= 0) { bound_one = true; } else if (!weak) { die("Failed to bind port %u (%s) for option '-%c %s'", - i, strerror_(-ret), optname, optarg); + i, strerror_(-fd), optname, optarg); } }

diff --git a/tcp.c b/tcp.c index 67007c05..80b47f3c 100644 --- a/tcp.c +++ b/tcp.c @@ -2680,7 +2680,7 @@ void tcp_sock_handler(const struct ctx *c, union epoll_ref ref, * @ifname: Name of interface to bind to, NULL for any * @port: Port, host order * - * Return: 0 on success, negative error code on failure + * Return: Socket fd on success, negative error code on failure

Nit, here and on udp_listen(): "socket". See also 9e0423e13541 ("style: Fix 'Return' comment style").

*/ int tcp_listen(const struct ctx *c, uint8_t pif, const union inany_addr *addr, const char *ifname, in_port_t port) @@ -2729,10 +2729,7 @@ int tcp_listen(const struct ctx *c, uint8_t pif, socks[port][V6] = s < 0 ? -1 : s; }

- if (s < 0) - return s; - - return 0; + return s; }

/** diff --git a/udp.c b/udp.c index 8cfa1e1f..63dc7c25 100644 --- a/udp.c +++ b/udp.c @@ -1136,7 +1136,7 @@ int udp_tap_handler(const struct ctx *c, uint8_t pif, * @ifname: Name of interface to bind to, NULL if not configured * @port: Port, host order * - * Return: 0 on success, negative error code on failure + * Return: Socket fd on success, negative error code on failure */ int udp_listen(const struct ctx *c, uint8_t pif, const union inany_addr *addr, const char *ifname, in_port_t port) @@ -1180,7 +1180,7 @@ int udp_listen(const struct ctx *c, uint8_t pif, if (!addr || !inany_v4(addr)) socks[V6][port] = s < 0 ? -1 : s;

- return s < 0 ? s : 0; + return s; }

/**

-- Stefano