/*
  coins-syspro.c -- 情報科学類の授業「システムプログラム」で使うライブラリ
  ~yas/syspro/ipc/coins-syspro.c
*/
#include <stdio.h>
#include <stdlib.h>	/* malloc(), free() */
#include <sys/types.h>	/* socket() */
#include <sys/socket.h>	/* socket(), getnameinfo() */
#include <netdb.h>	/* getnameinfo() */
#include <string.h>	/* memcpy() */
#include <unistd.h>	/* gethostname() */
#include <ctype.h>	/* isdigit() */

#define PORTNO_BUFSIZE 30
#define	SOCKADDR_PRINT_BUFSIZE	1024
#define PRINT_MY_HOST_PORT_HOST_NAME_MAX 256

extern	int tcp_connect( char *server, int portno );
extern	void print_my_host_port( int portno );
extern	void tcp_sockaddr_print( int com );
extern	void tcp_peeraddr_print( int com );
extern	void sockaddr_print( struct sockaddr *addrp, socklen_t addr_len );
extern	int  tcp_acc_port( int portno, int pf );
extern	int  fdopen_sock( int sock, FILE **inp, FILE **outp );
extern	char *chomp( char *str );
extern	int  string_split( char *str, char del, int *countp, char ***vecp  );
extern	void free_string_vector( int qc, char **vec );
extern	int  countchr( char *s, char c );
extern char *get_query_string();
extern char *read_query_string();
extern void  safe_printenv( char *name );
extern void  safe_print_string( char *str );
extern char *html_escape( char *str );
extern char *decode_url( char *str );
extern char *getparam( int qc, char *qv[], char *name );

int
tcp_connect( char *server, int portno )
{
	struct addrinfo hints, *ai, *p;
	char portno_str[PORTNO_BUFSIZE];
	int s, err;
	snprintf( portno_str,sizeof(portno_str),"%d",portno );
	memset( &hints, 0, sizeof(hints) );
	hints.ai_socktype = SOCK_STREAM;
	if( (err = getaddrinfo( server, portno_str, &hints, &ai )) )
	{
		fprintf(stderr,"unknown server %s (%s)\n",server,
			gai_strerror(err) );
		goto error0;
	}
	for( p=ai ; p ; p=p->ai_next )
	{
		if( (s = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) < 0 )
		{
			perror("socket");
			goto error1;
		}
		if( connect(s, p->ai_addr, p->ai_addrlen) >= 0 )
		{
			break;
		}
		else
		{
			close( s );
		}
	}
	freeaddrinfo( ai );
	return( s );
error1:
	freeaddrinfo( ai );
error0:
	return( -1 );
}

void
print_my_host_port( int portno )
{
	char hostname[PRINT_MY_HOST_PORT_HOST_NAME_MAX+1] ;

	gethostname( hostname,PRINT_MY_HOST_PORT_HOST_NAME_MAX );
	hostname[PRINT_MY_HOST_PORT_HOST_NAME_MAX] = 0 ;
	printf("run telnet %s %d \n", hostname, portno );
}

void
tcp_sockaddr_print( int com )
{
	struct sockaddr_storage addr ;
	socklen_t addr_len ; /* macOS: __uint32_t, Linux: unsigned int */

	addr_len = sizeof( addr );
    	if( getsockname( com, (struct sockaddr *)&addr, &addr_len  )<0 )
	{
		perror("tcp_peeraddr_print");
		return;
	}
	sockaddr_print( (struct sockaddr *)&addr, addr_len );
	printf("\n");
}

void
tcp_peeraddr_print( int com )
{
	struct sockaddr_storage addr ;
	socklen_t addr_len ; /* macOS: __uint32_t, Linux: unsigned int */

	addr_len = sizeof( addr );
    	if( getpeername( com, (struct sockaddr *)&addr, &addr_len  )<0 )
	{
		perror("tcp_peeraddr_print");
		return;
	}
	sockaddr_print( (struct sockaddr *)&addr, addr_len );
	printf("\n");
}

void
sockaddr_print( struct sockaddr *addrp, socklen_t addr_len )
{
	char host[SOCKADDR_PRINT_BUFSIZE] ;
	char port[SOCKADDR_PRINT_BUFSIZE] ;

	if( getnameinfo(addrp, addr_len, host, sizeof(host),
			port, sizeof(port), NI_NUMERICHOST|NI_NUMERICSERV)<0 )
		return;
	if( addrp->sa_family == PF_INET )
		printf("%s:%s", host, port );
	else
		printf("[%s]:%s", host, port );
}

int
tcp_acc_port( int portno, int ip_version )
{
	struct addrinfo hints, *ai;
	char portno_str[PORTNO_BUFSIZE];
	int err, s, on, pf;

    	switch( ip_version )
	{
	case 4:
		pf = PF_INET;
		break;
	case 6:
#if	!defined(IPV6_V6ONLY)
		fprintf(stderr,"Sorry, IPV6_V6ONLY is not supported in this system.\n");
		goto error0;
#endif	/*IPV6_V6ONLY*/
		pf = PF_INET6;
		break;
	case 0:
	case 46:
	case 64:
		pf = PF_INET6; /* pf = 0; in macOS */
		break;
	default:
		fprintf(stderr,"bad IP version: %d.  4 or 6 is allowed.\n",
			ip_version );
		goto error0;
	}
	snprintf( portno_str,sizeof(portno_str),"%d",portno );
	memset( &hints, 0, sizeof(hints) );
	ai = NULL;
	hints.ai_family   = pf ;
	hints.ai_flags    = AI_PASSIVE;
	hints.ai_socktype = SOCK_STREAM ;
	if( (err = getaddrinfo( NULL, portno_str, &hints, &ai )) )
	{
		fprintf(stderr,"bad portno %d? (%s)\n",portno,
			gai_strerror(err) );
		goto error0;
	}
	if( (s = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol)) < 0 )
	{
		perror("socket");
		goto error1;
	}

#ifdef	IPV6_V6ONLY
	if( ai->ai_family == PF_INET6 && ip_version == 6 )
	{
		on = 1;
		if( setsockopt(s,IPPROTO_IPV6, IPV6_V6ONLY,&on,sizeof(on)) < 0 )
		{
			perror("setsockopt(,,IPV6_V6ONLY)");
			goto error1;
		}
	}
#endif	/*IPV6_V6ONLY*/

	if( bind(s,ai->ai_addr,ai->ai_addrlen) < 0 )
	{
		perror("bind");
		fprintf(stderr,"Port number %d\n", portno );
		goto error2;
	}
	on = 1;
	if( setsockopt( s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on) ) < 0 )
	{
		perror("setsockopt(,,SO_REUSEADDR)");
		goto error2;
	}
	if( listen( s, 5 ) < 0 )
	{
		perror("listen");
		goto error2;
	}
	freeaddrinfo( ai );
	return( s );

error2:
	close( s );	
error1:
	freeaddrinfo( ai );
error0:
	return( -1 );
}

int
fdopen_sock( int sock, FILE **inp, FILE **outp )
{
	int sock2 ;

	if( (sock2=dup(sock)) < 0 )
	{
		return( -1 );
	}
	if( (*inp = fdopen( sock2, "r" )) == NULL )
	{
		close( sock2 );
		return( -1 );
	}
	if( (*outp = fdopen( sock, "w" )) == NULL )
	{
		fclose( *inp );
		*inp = 0 ;
		return( -1 );
	}
	setvbuf(*outp, (char *)NULL, _IONBF, 0);
	return( 0 );
}

char *
chomp( char *str )
{
	int len ;

	len = strlen( str );
	if( len>=2 && str[len-2] == '\r' && str[len-1] == '\n' )
	{
		str[len-2] = str[len-1] = 0;
	}
	else if( len >= 1 && (str[len-1] == '\r' || str[len-1] == '\n') )
	{
		str[len-1] = 0;
	}
	return( str );
}

int
string_split( char *str, char del, int *countp, char ***vecp  )
{
	char **vec ;
	int  count_max, i, len ;
	char *s, *p ;

	if( str == 0 )
		return( -1 );
	count_max = countchr(str,del)+1 ;
	vec = malloc( sizeof(char *)*(count_max+1) );
	if( vec == 0 )
		return( -1 );

	for( i=0 ; i<count_max ; i++ )
	{
		while( *str == del )
			str ++ ;
		if( *str == 0 )
			break;
		for( p = str ; *p!=del && *p!=0 ; p++ )
			continue;
		/* *p == del || *p=='\0' */
		len =  p - str ;
		s = malloc( len+1 );
		if( s == 0 )
		{
			int j ;
			for( j=0 ; j<i; j++ )
			{
				free( vec[j] );
				vec[j] = 0 ;
			}
			free( vec );
			return( -1 );
		}
		memcpy( s, str, len );
		s[len] = 0 ;
		vec[i] = s ;
		str = p ;
	}
	vec[i] = 0 ;
	*countp = i ;
	*vecp = vec ;
	return( i );
}

void
free_string_vector( int qc, char **vec )
{
	int i ;
    	for( i=0 ; i<qc ; i++ )
	{
		if( vec[i] == NULL )
			break;
		free( vec[i] );
	}
	free( vec );
}

int
countchr( char *s, char c )
{
	int count ;
	for( count=0 ; *s ; s++ )
		if( *s == c )
			count ++ ;
	return( count );
}

char *
get_query_string()
{
	char *request_method, *query_string;
	request_method = getenv("REQUEST_METHOD");
	if( request_method == 0 )
		return( 0 );
	else if( strcmp(request_method,"GET") == 0 )
	{
		query_string = getenv("QUERY_STRING");
		if( query_string == 0 )
			return( 0 );
		else
			return( strdup(query_string) );
	}
	else if( strcmp(request_method,"POST") == 0 )
	{
		return( read_query_string() );
	}
	else
	{
		printf("Unknown method: ");
		safe_print_string( request_method );
		printf("\n");
		return( 0 );
	}
}

char *
read_query_string()
{
	int   clen ;
	char *content_length ;
	char *buf ;

	content_length = getenv("CONTENT_LENGTH");
	if( content_length == 0 )
	{
		return( 0 );
	}
	else
	{
		clen = strtol( content_length,0,10 );
		buf = malloc( clen + 1 );
		if( buf == 0 )
		{
			printf("read_query_string(): no memory\n");
			exit( -1 );
		}
		if( read(0,buf,clen) != clen )
		{
			printf("read error.\n");
			exit( -1 );
		}
		buf[clen] = 0 ;
		return( buf );
	}
}

void
safe_printenv( char *name )
{
	char *val ;
	char *safe_val ;

	printf("%s=",name );
    	val = getenv( name );
	safe_print_string( val );
	printf("\n");
}


void
safe_print_string( char *str )
{
	char *safe_str ;

	if( str == 0 )
	{
		printf("(null)");
		return;
	}
	safe_str = html_escape( str );
	if( safe_str == 0 )
	{
		printf("(no memory)");
	}
	else
	{
		printf("%s",safe_str );
		free( safe_str );
	}
}

char *
html_escape( char *str )
{
	int len ;
	char c, *tmp, *p, *res ;

	len = strlen( str );
	tmp = malloc( len * 6 + 1 );
	if( tmp == 0 )
		return( 0 );
	p = tmp ;
	while( (c = *str++) )
	{
		switch( c )
		{
		case '&': memcpy(p,"&amp;", 5); p += 5 ; break;
		case '<': memcpy(p,"&lt;",  4); p += 4 ; break;
		case '>': memcpy(p,"&gt;",  4); p += 4 ; break;
		case '"': memcpy(p,"&quot;",6); p += 6 ; break;
		default:  *p = c ;              p++ ;    break;
		}
	}
	*p = 0 ;
	res = strdup( tmp );
	free( tmp );
	return( res );
}

char *
decode_url( char *str )
{
	int len ;
	char c, *tmp, *p, *res ;

	len = strlen( str );
	tmp = malloc( len + 1 );
	if( tmp == 0 )
		return( 0 );
	p = tmp ;

	while( *str )
	{
		if( *str == '%' && isxdigit(*(str+1)) && isxdigit(*(str+2)) )
		{
			char hexstr[3] ;
			hexstr[0] = *(str+1);
			hexstr[1] = *(str+2);
			hexstr[2] = 0 ;
			c = strtol( hexstr, 0, 16 );
			*p ++ = c ;
			str += 3 ;
		}
		else if( *str == '+' )
		{
			*p ++ = ' ' ;
			str ++ ;
		}
		else
		{
			*p ++ = *str ;
			str ++ ;
		}
	}
	*p = 0 ;
	res = strdup( tmp );
	free( tmp );
	return( res );
}

char *
getparam( int qc, char *qv[], char *name )
{
	int i;
	size_t len;

	len = strlen( name );
	for( i=0; i<qc; i++ )
	{
		if( strncmp(qv[i],name,len) == 0 &&
		    qv[i][len] == '=' )
		{
			return( &qv[i][len+1] );
		}
	}
	return( NULL );
}