On Wed, 19 Feb 2025 14:54:44 +1100 David Gibson <david(a)gibson.dropbear.id.au> wrote:In conf_ports() we have three different paths which actually do the setup of an individual forwarded port: one for the "all" case, one for the exclusions only case and one for the range of ports with possible exclusions case. We can unify those cases using a new helper which handles a single range of ports, with a bitmap of exclusions. Although this is slightly longer (largely due to the new helpers function comment), it reduces duplicated logic. It will also make future improvements to the tracking of port forwards easier. Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au> --- conf.c | 175 +++++++++++++++++++++++++++++---------------------------- 1 file changed, 90 insertions(+), 85 deletions(-) diff --git a/conf.c b/conf.c index 18017f51..f862845b 100644 --- a/conf.c +++ b/conf.c @@ -123,6 +123,75 @@ static int parse_port_range(const char *s, char **endptr, return 0; } +/** + * conf_ports_range_except() - Set up forwarding for a range of ports minus a + * bitmap of exclusions + * @c: Execution context + * @optname: Short option name, t, T, u, or U + * @optarg: Option argument (port specification) + * @fwd: Pointer to @fwd_ports to be updated + * @addr: Listening address + * @ifname: Listening interface + * @first: First port to forward + * @last: Last port to forward + * @exclude: Bitmap of ports to exclude + * @to: Port to translate @first to when forwarding + * @weak: Ignore errors, as long as at least one port is mapped + */ +static void conf_ports_range_except(const struct ctx *c, char optname, + const char *optarg, struct fwd_ports *fwd, + const union inany_addr *addr, + const char *ifname, + uint16_t first, uint16_t last, + const uint8_t *exclude, uint16_t to, + bool weak)...ouch, bool anything_else? I think this patch is strictly better than the existing duplication, so I'm fine with it as it is. I don't see any obvious way to make the prototype smaller (other than things that would reduce readability by hiding information), so... yeah. I just wanted to mention that the prototype is a bit heavy.+{ + bool bound_one = false; + unsigned i; + int ret; + + if (first == 0) { + die("Can't forward port 0 for option '-%c %s'", + optname, optarg); + } + + for (i = first; i <= last; i++) { + if (bitmap_isset(exclude, i)) + continue; + + if (bitmap_isset(fwd->map, i)) { + warn( +"Altering mapping of already mapped port number: %s", optarg); + } + + bitmap_set(fwd->map, i); + fwd->delta[i] = to - first; + + if (optname == 't') + ret = tcp_sock_init(c, addr, ifname, i); + else if (optname == 'u') + ret = udp_sock_init(c, 0, addr, ifname, i); + else + /* No way to check in advance for -T and -U */ + ret = 0; + + if (ret == -ENFILE || ret == -EMFILE) { + die("Can't open enough sockets for port specifier: %s", + optarg); + } + + if (!ret) { + bound_one = true; + } else if (!weak) { + die("Failed to bind port %u (%s) for option '-%c %s'", + i, strerror_(-ret), optname, optarg); + } + } + + if (!bound_one) + die("Failed to bind any port for '-%c %s'", optname, optarg); +} + /** * conf_ports() - Parse port configuration options, initialise UDP/TCP sockets * @c: Execution context @@ -135,10 +204,9 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg, { union inany_addr addr_buf = inany_any6, *addr = &addr_buf; char buf[BUFSIZ], *spec, *ifname = NULL, *p; - bool exclude_only = true, bound_one = false; uint8_t exclude[PORT_BITMAP_SIZE] = { 0 }; + bool exclude_only = true; unsigned i; - int ret; if (!strcmp(optarg, "none")) { if (fwd->mode) @@ -173,32 +241,14 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg, fwd->mode = FWD_ALL; - /* Skip port 0. It has special meaning for many socket APIs, so - * trying to bind it is not really safe. - */ - for (i = 1; i < NUM_PORTS; i++) { + /* Also exclude ephemeral ports */"Also" implies the reader figures out that conf_ports_range_except() skips port zero while looking at this line, which is not really something you can expect, I guess. We could probably just drop this comment, or change it as you did below.+ for (i = 0; i < NUM_PORTS; i++) if (fwd_port_is_ephemeral(i)) - continue; - - bitmap_set(fwd->map, i); - if (optname == 't') { - ret = tcp_sock_init(c, NULL, NULL, i); - if (ret == -ENFILE || ret == -EMFILE) - goto enfile; - if (!ret) - bound_one = true; - } else if (optname == 'u') { - ret = udp_sock_init(c, 0, NULL, NULL, i); - if (ret == -ENFILE || ret == -EMFILE) - goto enfile; - if (!ret) - bound_one = true; - } - } - - if (!bound_one) - goto bind_all_fail; - + bitmap_set(exclude, i);I would add an extra blank line here, otherwise it's quite confusing.+ conf_ports_range_except(c, optname, optarg, fwd, + NULL, NULL, + 1, NUM_PORTS - 1, exclude, + 1, true); return; } @@ -275,37 +325,14 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg, } while ((p = next_chunk(p, ','))); if (exclude_only) { - /* Skip port 0. It has special meaning for many socket APIs, so - * trying to bind it is not really safe. - */ - for (i = 1; i < NUM_PORTS; i++) { - if (fwd_port_is_ephemeral(i) || - bitmap_isset(exclude, i)) - continue; - - bitmap_set(fwd->map, i); - - if (optname == 't') { - ret = tcp_sock_init(c, addr, ifname, i); - if (ret == -ENFILE || ret == -EMFILE) - goto enfile; - if (!ret) - bound_one = true; - } else if (optname == 'u') { - ret = udp_sock_init(c, 0, addr, ifname, i); - if (ret == -ENFILE || ret == -EMFILE) - goto enfile; - if (!ret) - bound_one = true; - } else { - /* No way to check in advance for -T and -U */ - bound_one = true; - } - } - - if (!bound_one) - goto bind_all_fail; - + /* Exclude ephemeral ports */ + for (i = 0; i < NUM_PORTS; i++) + if (fwd_port_is_ephemeral(i)) + bitmap_set(exclude, i);Same here, a blank line would be nice.+ conf_ports_range_except(c, optname, optarg, fwd, + addr, ifname, + 1, NUM_PORTS - 1, exclude, + 1, true); return; } @@ -334,40 +361,18 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg, if ((*p != '\0') && (*p != ',')) /* Garbage after the ranges */ goto bad; - for (i = orig_range.first; i <= orig_range.last; i++) { - if (bitmap_isset(fwd->map, i)) - warn( -"Altering mapping of already mapped port number: %s", optarg); - - if (bitmap_isset(exclude, i)) - continue; - - bitmap_set(fwd->map, i); - - fwd->delta[i] = mapped_range.first - orig_range.first; - - ret = 0; - if (optname == 't') - ret = tcp_sock_init(c, addr, ifname, i); - else if (optname == 'u') - ret = udp_sock_init(c, 0, addr, ifname, i); - if (ret) - goto bind_fail; - } + conf_ports_range_except(c, optname, optarg, fwd, + addr, ifname, + orig_range.first, orig_range.last, + exclude, + mapped_range.first, false); } while ((p = next_chunk(p, ','))); return; -enfile: - die("Can't open enough sockets for port specifier: %s", optarg); bad: die("Invalid port specifier %s", optarg); mode_conflict: die("Port forwarding mode '%s' conflicts with previous mode", optarg); -bind_fail: - die("Failed to bind port %u (%s) for option '-%c %s', exiting", - i, strerror_(-ret), optname, optarg); -bind_all_fail: - die("Failed to bind any port for '-%c %s', exiting", optname, optarg); } /**-- Stefano