[PATCH rfc 2/2] fabrics: allow user to pass hostname instead of traddr

[Sagi Grimberg <sagi@grimberg.me>]

Some users would like to use well known hostnames instead
of remembering ip addresses. So, allow users to pass --hostname
and we will attempt to resolve against the DNS.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
---
 fabrics.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/fabrics.c b/fabrics.c
index a7d628b1f0c9..7bd95c4b0d10 100644
--- a/fabrics.c
+++ b/fabrics.c
@@ -33,6 +33,10 @@
 #include <sys/stat.h>
 #include <stddef.h>
 
+#include <sys/types.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
 #include "util/parser.h"
 #include "nvme-ioctl.h"
 #include "nvme-status.h"
@@ -60,6 +64,7 @@ static struct config {
 	char *nqn;
 	char *transport;
 	char *traddr;
+	char *hostname;
 	char *trsvcid;
 	char *host_traddr;
 	char *hostnqn;
@@ -857,6 +862,54 @@ static int build_options(char *argstr, int max_len, bool discover)
 	return 0;
 }
 
+static int hostname2traddr(struct config *cfg)
+{
+	struct addrinfo *host_info, hints = {.ai_family = AF_UNSPEC};
+	char addrstr[NVMF_TRADDR_SIZE];
+	const char *p;
+	int ret;
+
+	if (cfg->traddr) {
+		fprintf(stderr, "hostname and traddr cannot be passed together\n");
+		return -EINVAL;
+	}
+
+	ret = getaddrinfo(cfg->hostname, NULL, &hints, &host_info);
+	if (ret) {
+		fprintf(stderr, "failed to get host info for %s\n", cfg->hostname);
+		return ret;
+	}
+
+	switch (host_info->ai_family) {
+	case AF_INET:
+		p = inet_ntop(host_info->ai_family,
+			&(((struct sockaddr_in *)host_info->ai_addr)->sin_addr),
+			addrstr, NVMF_TRADDR_SIZE);
+		break;
+	case AF_INET6:
+		p = inet_ntop(host_info->ai_family,
+			&(((struct sockaddr_in6 *)host_info->ai_addr)->sin6_addr),
+			addrstr, NVMF_TRADDR_SIZE);
+		break;
+	default:
+		fprintf(stderr, "unrecognized address family (%d) %s\n",
+			host_info->ai_family, cfg->hostname);
+		ret = -EINVAL;
+		goto free_addrinfo;
+	}
+
+	if (!p) {
+		fprintf(stderr, "failed to get traddr for %s\n", cfg->hostname);
+		ret = -errno;
+		goto free_addrinfo;
+	}
+	cfg->traddr = strdup(addrstr);
+
+free_addrinfo:
+	freeaddrinfo(host_info);
+	return ret;
+}
+
 static int connect_ctrl(struct nvmf_disc_rsp_page_entry *e)
 {
 	char argstr[BUF_SIZE], *p;
@@ -1230,6 +1283,13 @@ static int discover_from_conf_file(const char *desc, char *argstr,
 		if (cfg.persistent && !cfg.keep_alive_tmo)
 			cfg.keep_alive_tmo = NVMF_DEF_DISC_TMO;
 
+		if (cfg.hostname) {
+			ret = hostname2traddr(&cfg);
+			if (ret)
+				goto out;
+			cfg.hostname = NULL;
+		}
+
 		err = build_options(argstr, BUF_SIZE, true);
 		if (err) {
 			ret = err;
@@ -1259,6 +1319,7 @@ int fabrics_discover(const char *desc, int argc, char **argv, bool connect)
 	OPT_ARGS(opts) = {
 		OPT_LIST("transport",      't', &cfg.transport,       "transport type"),
 		OPT_LIST("traddr",         'a', &cfg.traddr,          "transport address"),
+		OPT_LIST("hostname",       'A', &cfg.hostname,        "transport address in a hostname form"),
 		OPT_LIST("trsvcid",        's', &cfg.trsvcid,         "transport service id (e.g. IP port)"),
 		OPT_LIST("host-traddr",    'w', &cfg.host_traddr,     "host traddr (e.g. FC WWN's)"),
 		OPT_LIST("hostnqn",        'q', &cfg.hostnqn,         "user-defined hostnqn (if default not used)"),
@@ -1295,6 +1356,13 @@ int fabrics_discover(const char *desc, int argc, char **argv, bool connect)
 	} else {
 		if (cfg.persistent && !cfg.keep_alive_tmo)
 			cfg.keep_alive_tmo = NVMF_DEF_DISC_TMO;
+
+		if (cfg.hostname) {
+			ret = hostname2traddr(&cfg);
+			if (ret)
+				goto out;
+		}
+
 		ret = build_options(argstr, BUF_SIZE, true);
 		if (ret)
 			goto out;
@@ -1315,6 +1383,7 @@ int fabrics_connect(const char *desc, int argc, char **argv)
 		OPT_LIST("transport",         't', &cfg.transport,         "transport type"),
 		OPT_LIST("nqn",               'n', &cfg.nqn,               "nqn name"),
 		OPT_LIST("traddr",            'a', &cfg.traddr,            "transport address"),
+		OPT_LIST("hostname",          'A', &cfg.hostname,          "transport address in a hostname form"),
 		OPT_LIST("trsvcid",           's', &cfg.trsvcid,           "transport service id (e.g. IP port)"),
 		OPT_LIST("host-traddr",       'w', &cfg.host_traddr,       "host traddr (e.g. FC WWN's)"),
 		OPT_LIST("hostnqn",           'q', &cfg.hostnqn,           "user-defined hostnqn"),
@@ -1339,6 +1408,12 @@ int fabrics_connect(const char *desc, int argc, char **argv)
 	if (ret)
 		goto out;
 
+	if (cfg.hostname) {
+		ret = hostname2traddr(&cfg);
+		if (ret)
+			goto out;
+	}
+
 	ret = build_options(argstr, BUF_SIZE, false);
 	if (ret)
 		goto out;
-- 
2.20.1


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