diff options
author | Thomas Haller <thaller@redhat.com> | 2023-08-18 16:08:19 +0200 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2023-08-20 23:48:26 +0200 |
commit | 7076523e482110d59c4456f4a795581a2ca39c41 (patch) | |
tree | 9b1cf7707f110fd3402dae19419b17722f66dfd2 /src/nftutils.c | |
parent | 4646d656466b1f05bd765bbfb4d6d7bf1529bdbd (diff) |
nftutils: add and use wrappers for getprotoby{name,number}_r(), getservbyport_r()
We should aim to use the thread-safe variants of getprotoby{name,number}
and getservbyport(). However, they may not be available with other libc,
so it requires a configure check. As that is cumbersome, add wrappers
that do that at one place.
These wrappers are thread-safe, if libc provides the reentrant versions.
Use them.
Signed-off-by: Thomas Haller <thaller@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'src/nftutils.c')
-rw-r--r-- | src/nftutils.c | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/src/nftutils.c b/src/nftutils.c new file mode 100644 index 00000000..13f879dd --- /dev/null +++ b/src/nftutils.c @@ -0,0 +1,102 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include <config.h> + +#include "nftutils.h" + +#include <netdb.h> +#include <string.h> +#include <stdint.h> + +/* Buffer size used for getprotobynumber_r() and similar. The manual comments + * that a buffer of 1024 should be sufficient "for most applications"(??), so + * let's double it. It still fits reasonably on the stack, so no need to + * choose a smaller one. */ +#define NETDB_BUFSIZE 2048 + +bool nft_getprotobynumber(int proto, char *out_name, size_t name_len) +{ + const struct protoent *result; + +#if HAVE_DECL_GETPROTOBYNUMBER_R + struct protoent result_buf; + char buf[NETDB_BUFSIZE]; + int r; + + r = getprotobynumber_r(proto, + &result_buf, + buf, + sizeof(buf), + (struct protoent **) &result); + if (r != 0 || result != &result_buf) + result = NULL; +#else + result = getprotobynumber(proto); +#endif + + if (!result) + return false; + + if (strlen(result->p_name) >= name_len) + return false; + strcpy(out_name, result->p_name); + return true; +} + +int nft_getprotobyname(const char *name) +{ + const struct protoent *result; + +#if HAVE_DECL_GETPROTOBYNAME_R + struct protoent result_buf; + char buf[NETDB_BUFSIZE]; + int r; + + r = getprotobyname_r(name, + &result_buf, + buf, + sizeof(buf), + (struct protoent **) &result); + if (r != 0 || result != &result_buf) + result = NULL; +#else + result = getprotobyname(name); +#endif + + if (!result) + return -1; + + if (result->p_proto < 0 || result->p_proto > UINT8_MAX) + return -1; + return (uint8_t) result->p_proto; +} + +bool nft_getservbyport(int port, const char *proto, char *out_name, size_t name_len) +{ + const struct servent *result; + +#if HAVE_DECL_GETSERVBYPORT_R + struct servent result_buf; + char buf[NETDB_BUFSIZE]; + int r; + + r = getservbyport_r(port, + proto, + &result_buf, + buf, + sizeof(buf), + (struct servent**) &result); + if (r != 0 || result != &result_buf) + result = NULL; +#else + result = getservbyport(port, proto); +#endif + + if (!result) + return false; + + if (strlen(result->s_name) >= name_len) + return false; + strcpy(out_name, result->s_name); + return true; +} |