shared/socket-util: add function to query remote address

src/shared/socket-util.c

@@ -31,6 +31,7 @@
 #include <sys/stat.h>
 #include <stddef.h>
 #include <sys/ioctl.h>
+#include <netdb.h>
 
 #include "macro.h"
 #include "util.h"
@@ -574,13 +575,12 @@ int sockaddr_pretty(const struct sockaddr *_sa, socklen_t salen, bool translate_
 
 int getpeername_pretty(int fd, char **ret) {
         union sockaddr_union sa;
-        socklen_t salen;
+        socklen_t salen = sizeof(sa);
         int r;
 
         assert(fd >= 0);
         assert(ret);
 
-        salen = sizeof(sa);
         if (getpeername(fd, &sa.sa, &salen) < 0)
                 return -errno;
 
@@ -608,12 +608,11 @@ int getpeername_pretty(int fd, char **ret) {
 
 int getsockname_pretty(int fd, char **ret) {
         union sockaddr_union sa;
-        socklen_t salen;
+        socklen_t salen = sizeof(sa);
 
         assert(fd >= 0);
         assert(ret);
 
-        salen = sizeof(sa);
         if (getsockname(fd, &sa.sa, &salen) < 0)
                 return -errno;
 
@@ -625,6 +624,49 @@ int getsockname_pretty(int fd, char **ret) {
         return sockaddr_pretty(&sa.sa, salen, false, ret);
 }
 
+int socknameinfo_pretty(union sockaddr_union *sa, socklen_t salen, char **_ret) {
+        int r;
+        char host[NI_MAXHOST], *ret;
+
+        assert(_ret);
+
+        r = getnameinfo(&sa->sa, salen, host, sizeof(host), NULL, 0,
+                        NI_IDN|NI_IDN_USE_STD3_ASCII_RULES);
+        if (r != 0) {
+                _cleanup_free_ char *sockname = NULL;
+                int saved_errno = errno;
+
+                r = sockaddr_pretty(&sa->sa, salen, true, &sockname);
+                if (r < 0)
+                        log_error("sockadd_pretty() failed: %s", strerror(-r));
+                else
+                        log_error("getnameinfo(%s) failed: %s", sockname, strerror(-r));
+                return -saved_errno;
+        }
+
+        ret = strdup(host);
+        if (!ret)
+                return log_oom();
+
+        *_ret = ret;
+        return 0;
+}
+
+int getnameinfo_pretty(int fd, char **ret) {
+        union sockaddr_union sa;
+        socklen_t salen = sizeof(sa);
+
+        assert(fd >= 0);
+        assert(ret);
+
+        if (getsockname(fd, &sa.sa, &salen) < 0) {
+                log_error("getsockname(%d) failed: %m", fd);
+                return -errno;
+        }
+
+        return socknameinfo_pretty(&sa, salen, ret);
+}
+
 int socket_address_unlink(SocketAddress *a) {
         assert(a);
 

src/shared/socket-util.h

@@ -101,6 +101,9 @@ int sockaddr_pretty(const struct sockaddr *_sa, socklen_t salen, bool translate_
 int getpeername_pretty(int fd, char **ret);
 int getsockname_pretty(int fd, char **ret);
 
+int socknameinfo_pretty(union sockaddr_union *sa, socklen_t salen, char **_ret);
+int getnameinfo_pretty(int fd, char **ret);
+
 const char* socket_address_bind_ipv6_only_to_string(SocketAddressBindIPv6Only b) _const_;
 SocketAddressBindIPv6Only socket_address_bind_ipv6_only_from_string(const char *s) _pure_;
 

src/test/test-socket-util.c

@@ -22,6 +22,7 @@
 #include "util.h"
 #include "macro.h"
 #include "log.h"
+#include "async.h"
 
 static void test_socket_address_parse(void) {
         SocketAddress a;
@@ -212,6 +213,58 @@ static void test_in_addr_prefix_next(void) {
 
 }
 
+static void *connect_thread(void *arg) {
+        union sockaddr_union *sa = arg;
+        _cleanup_close_ int fd = -1;
+
+        fd = socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC, 0);
+        assert(fd >= 0);
+
+        assert_se(connect(fd, &sa->sa, sizeof(sa->in)) == 0);
+
+        return NULL;
+}
+
+static void test_nameinfo_pretty(void) {
+        _cleanup_free_ char *stdin = NULL, *localhost = NULL;
+
+        union sockaddr_union s = {
+                .in.sin_family = AF_INET,
+                .in.sin_port = 0,
+                .in.sin_addr.s_addr = htonl(INADDR_ANY),
+        };
+        int r;
+
+        union sockaddr_union c = {};
+        socklen_t slen = sizeof(c.in), clen = sizeof(c.in);
+
+        _cleanup_close_ int sfd = -1, cfd = -1, afd = -1;
+        r = getnameinfo_pretty(STDIN_FILENO, &stdin);
+        log_info("No connection remote: %s", strerror(-r));
+
+        assert_se(r < 0);
+
+        sfd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC, 0);
+        assert(sfd >= 0);
+
+        assert_se(bind(sfd, &s.sa, sizeof(s.in)) == 0);
+
+        /* find out the port number */
+        assert_se(getsockname(sfd, &s.sa, &slen) == 0);
+
+        assert_se(listen(sfd, 1) == 0);
+
+        assert_se(asynchronous_job(connect_thread, &s) == 0);
+
+        log_debug("Accepting new connection on fd:%d", sfd);
+        cfd = accept4(sfd, &c.sa, &clen, SOCK_CLOEXEC);
+        assert(cfd >= 0);
+
+        r = getnameinfo_pretty(cfd, &localhost);
+        log_info("Connection from %s", localhost);
+        assert(r == 0);
+}
+
 int main(int argc, char *argv[]) {
 
         log_set_max_level(LOG_DEBUG);
@@ -224,5 +277,7 @@ int main(int argc, char *argv[]) {
         test_in_addr_prefix_intersect();
         test_in_addr_prefix_next();
 
+        test_nameinfo_pretty();
+
         return 0;
 }