[CRIU] [PATCHv3 4/8] util: Enable hostname resolution of tcp address

[Radostin Stoyanov]

On 10/09/18 20:04, Andrei Vagin wrote:
> On Tue, Sep 04, 2018 at 10:26:53PM +0100, Radostin Stoyanov wrote:
>> Add hostname resolution in setup_tcp_client(). This change allows a
>> valid hostname to be provided as value for the --address option when
>> connecting to page server.
>>
>> Signed-off-by: Radostin Stoyanov <rstoyanov1 at gmail.com>
>> ---
>>  Documentation/criu.txt |  2 +-
>>  criu/include/util.h    |  2 +-
>>  criu/util.c            | 56 +++++++++++++++++++++++++++++++-----------
>>  3 files changed, 44 insertions(+), 16 deletions(-)
>>
>> diff --git a/Documentation/criu.txt b/Documentation/criu.txt
>> index 6bb3f0f5..04e7a610 100644
>> --- a/Documentation/criu.txt
>> +++ b/Documentation/criu.txt
>> @@ -550,7 +550,7 @@ Launches *criu* in page server mode.
>>      It isn't supposed to use --daemon and --status-fd together.
>>  
>>  *--address* 'address'::
>> -    Page server IP address.
>> +    Page server IP address or hostname.
>>  
>>  *--port* 'number'::
>>      Page server port number.
>> diff --git a/criu/include/util.h b/criu/include/util.h
>> index b286b3e9..aba16818 100644
>> --- a/criu/include/util.h
>> +++ b/criu/include/util.h
>> @@ -293,7 +293,7 @@ void print_data(unsigned long addr, unsigned char *data, size_t size);
>>  
>>  int setup_tcp_server(char *type, char *addr, unsigned short *port);
>>  int run_tcp_server(bool daemon_mode, int *ask, int cfd, int sk);
>> -int setup_tcp_client(char *addr);
>> +int setup_tcp_client(char *hostname);
>>  
>>  #define LAST_PID_PATH		"sys/kernel/ns_last_pid"
>>  #define PID_MAX_PATH		"sys/kernel/pid_max"
>> diff --git a/criu/util.c b/criu/util.c
>> index 71bb2f6e..5c9fb306 100644
>> --- a/criu/util.c
>> +++ b/criu/util.c
>> @@ -30,6 +30,7 @@
>>  #include <sys/resource.h>
>>  #include <sys/wait.h>
>>  #include <sys/socket.h>
>> +#include <netdb.h>
>>  #include <netinet/in.h>
>>  #include <netinet/tcp.h>
>>  #include <sched.h>
>> @@ -1384,28 +1385,55 @@ out:
>>  	return -1;
>>  }
>>  
>> -int setup_tcp_client(char *addr)
>> +int setup_tcp_client(char *hostname)
>>  {
>>  	struct sockaddr_storage saddr;
>> -	int sk;
>> -
>> -	pr_info("Connecting to server %s:%u\n", addr, opts.port);
>> +	struct addrinfo addr_criteria, *addr_list, *p;
>> +	char ipstr[INET6_ADDRSTRLEN];
>> +	int sk = -1;
>> +	void *ip;
>>  
>> -	if (get_sockaddr_in(&saddr, addr, opts.port))
>> -		return -1;
>> +	memset(&addr_criteria, 0, sizeof(addr_criteria));
>> +	addr_criteria.ai_family = AF_UNSPEC;
>> +	addr_criteria.ai_socktype = SOCK_STREAM;
>> +	addr_criteria.ai_protocol = IPPROTO_TCP;
>>  
>> -	sk = socket(saddr.ss_family, SOCK_STREAM, IPPROTO_TCP);
>> -	if (sk < 0) {
>> -		pr_perror("Can't create socket");
>> -		return -1;
>> +	if (getaddrinfo(hostname, NULL, &addr_criteria, &addr_list)) {
>> +		pr_perror("Failed to resolve hostname: %s", hostname);
>> +		goto out;
>>  	}
>>  
>> -	if (connect(sk, (struct sockaddr *)&saddr, sizeof(saddr)) < 0) {
>> -		pr_perror("Can't connect to server");
>> -		close(sk);
>> -		return -1;
>> +	for(p = addr_list; p != NULL; p = p->ai_next) {
>> +
>> +		if (p->ai_family == AF_INET) {
>> +			struct sockaddr_in *ipv4 = (struct sockaddr_in *)p->ai_addr;
>> +			ip = &(ipv4->sin_addr);
>> +		} else {
>> +			struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)p->ai_addr;
>> +			ip = &(ipv6->sin6_addr);
>> +		}
>> +
>> +		inet_ntop(p->ai_family, ip, ipstr, sizeof(ipstr));
>> +		pr_info("Connecting to server %s:%u\n", ipstr, opts.port);
>> +
>> +		if (get_sockaddr_in(&saddr, ipstr, opts.port))
>> +			goto out;
>> +
>> +		sk = socket(saddr.ss_family, SOCK_STREAM, IPPROTO_TCP);
>> +		if (sk < 0) {
>> +			pr_perror("Can't create socket");
>> +			goto out;
>> +		}
>> +
>> +		if (connect(sk, (struct sockaddr *)&saddr, sizeof(saddr)) < 0) {
>> +			pr_info("Can't connect to server %s:%u\n", ipstr, opts.port);
>> +			close(sk);
>> +			sk = -1;
>> +		}
> How many sockets are we going to create? Why do we need this loop?
Oh, I just realised that I forgot to add break here (when the connection
is successful).

Thank you for pointing this out. I will resend the series.

Radostin
>
>>  	}
>>  
>> +out:
>> +	freeaddrinfo(addr_list);
>>  	return sk;
>>  }
>>  
>> -- 
>> 2.17.1
>>
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