The hostname is resolved just once since commit 58125210ab3b ("Tools: hv: cache FQDN in kvp_daemon to avoid timeouts") to make sure the VM responds within the timeout limits to requests from the host. If for some reason getaddrinfo fails, the string returned by the "FullyQualifiedDomainName" request contains some error string, which is then used by tools on the host side. Adjust the code to resolve the current hostname in a separate thread. This thread loops until getaddrinfo returns success. During this time all "FullyQualifiedDomainName" requests will be answered with an empty string. Signed-off-by: Olaf Hering <olaf@xxxxxxxxx> --- tools/hv/Makefile | 2 ++ tools/hv/hv_kvp_daemon.c | 69 ++++++++++++++++++++++++++++++++---------------- 2 files changed, 48 insertions(+), 23 deletions(-) diff --git a/tools/hv/Makefile b/tools/hv/Makefile index b57143d9459c..3b5481015a84 100644 --- a/tools/hv/Makefile +++ b/tools/hv/Makefile @@ -22,6 +22,8 @@ ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS)) ALL_SCRIPTS := hv_get_dhcp_info.sh hv_get_dns_info.sh hv_set_ifconfig.sh +$(OUTPUT)hv_kvp_daemon: LDFLAGS += -lpthread + all: $(ALL_PROGRAMS) export srctree OUTPUT CC LD CFLAGS diff --git a/tools/hv/hv_kvp_daemon.c b/tools/hv/hv_kvp_daemon.c index e9ef4ca6a655..22cf1c4dbf5c 100644 --- a/tools/hv/hv_kvp_daemon.c +++ b/tools/hv/hv_kvp_daemon.c @@ -41,6 +41,7 @@ #include <net/if.h> #include <limits.h> #include <getopt.h> +#include <pthread.h> /* * KVP protocol: The user mode component first registers with the @@ -85,7 +86,7 @@ static char *processor_arch; static char *os_build; static char *os_version; static char *lic_version = "Unknown version"; -static char full_domain_name[HV_KVP_EXCHANGE_MAX_VALUE_SIZE]; +static char *full_domain_name; static struct utsname uts_buf; /* @@ -1327,27 +1328,53 @@ static int kvp_set_ip_info(char *if_name, struct hv_kvp_ipaddr_value *new_val) return error; } - -static void -kvp_get_domain_name(char *buffer, int length) +/* + * Async retrival of Fully Qualified Domain Name because getaddrinfo takes an + * unpredictable amount of time to finish. + */ +static void *kvp_getaddrinfo(void *p) { - struct addrinfo hints, *info ; - int error = 0; + char *tmp, **str_ptr = (char **)p; + char hostname[HOST_NAME_MAX + 1]; + struct addrinfo *info, hints = { + .ai_family = AF_INET, /* Get only ipv4 addrinfo. */ + .ai_socktype = SOCK_STREAM, + .ai_flags = AI_CANONNAME, + }; + int ret; + + if (gethostname(hostname, sizeof(hostname) - 1) < 0) + goto out; + + do { + ret = getaddrinfo(hostname, NULL, &hints, &info); + if (ret) + sleep(1); + } while (ret); + + ret = asprintf(&tmp, "%s", info->ai_canonname); + freeaddrinfo(info); + if (ret <= 0) + goto out; + + if (ret > HV_KVP_EXCHANGE_MAX_VALUE_SIZE) + tmp[HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1] = '\0'; + *str_ptr = tmp; - gethostname(buffer, length); - memset(&hints, 0, sizeof(hints)); - hints.ai_family = AF_INET; /*Get only ipv4 addrinfo. */ - hints.ai_socktype = SOCK_STREAM; - hints.ai_flags = AI_CANONNAME; +out: + pthread_exit(NULL); +} + +static void kvp_obtain_domain_name(char **str_ptr) +{ + pthread_t t; - error = getaddrinfo(buffer, NULL, &hints, &info); - if (error != 0) { - snprintf(buffer, length, "getaddrinfo failed: 0x%x %s", - error, gai_strerror(error)); + if (pthread_create(&t, NULL, kvp_getaddrinfo, str_ptr)) { + syslog(LOG_ERR, "pthread_create failed; error: %d %s", + errno, strerror(errno)); return; } - snprintf(buffer, length, "%s", info->ai_canonname); - freeaddrinfo(info); + pthread_detach(t); } void print_usage(char *argv[]) @@ -1412,11 +1439,7 @@ int main(int argc, char *argv[]) * Retrieve OS release information. */ kvp_get_os_info(); - /* - * Cache Fully Qualified Domain Name because getaddrinfo takes an - * unpredictable amount of time to finish. - */ - kvp_get_domain_name(full_domain_name, sizeof(full_domain_name)); + kvp_obtain_domain_name(&full_domain_name); if (kvp_file_init()) { syslog(LOG_ERR, "Failed to initialize the pools"); @@ -1571,7 +1594,7 @@ int main(int argc, char *argv[]) switch (hv_msg->body.kvp_enum_data.index) { case FullyQualifiedDomainName: - strcpy(key_value, full_domain_name); + strcpy(key_value, full_domain_name ? : ""); strcpy(key_name, "FullyQualifiedDomainName"); break; case IntegrationServicesVersion: