近期对json-rpc比較感兴趣，思想非常easy，并且看到了非常多不同语言的实现。在github上 hmngomes 的 json-rpc-c （实现的是server端，基于TCP流），短小精悍，提供了非常好的框架。代码十分清晰。易于扩展，并且代码easy看懂，非常经典。该实现依赖于其他两个库 libev 和 cJSON。值得认真学习。
測试的时候先启动server，而后通过 nc 命令发送对应的json格式数据，就会有对应的效果：
vonzhou@de15:~$ echo "{"method":"sayHello"}" | nc localhost 1234
{
"result": "Hello!"
}
vonzhou@de15:~$ echo "{"method":"exit"}" | nc localhost 1234
{
"result": "Bye!"
}
{
"result": "Hello!"
}
vonzhou@de15:~$ echo "{"method":"exit"}" | nc localhost 1234
{
"result": "Bye!"
}
以下贴出代码，便于温习。
-------------------server.c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <signal.h>
#include "jsonrpc-c.h"
#define PORT 1234 //
the port users will be connecting to
struct jrpc_server my_server;
cJSON * say_hello( jrpc_context *
ctx, cJSON * params, cJSON *id) {
return cJSON_CreateString( "Hello!" );
}
cJSON * exit_server( jrpc_context *
ctx, cJSON * params, cJSON *id) {
jrpc_server_stop(&my_server);
return cJSON_CreateString( "Bye!" );
}
int main( void )
{
jrpc_server_init(&my_server, PORT);
//注冊俩方法
jrpc_register_procedure(&my_server, say_hello, "sayHello" ,
NULL );
jrpc_register_procedure(&my_server, exit_server, "exit" ,
NULL );
jrpc_server_run(&my_server);
jrpc_server_destroy(&my_server);
return 0;
}
-----------------json-rpc.h
#ifndef JSONRPCC_H_
#define JSONRPCC_H_
#include "cJSON.h"
#include <ev.h>
/*
*
* http://www.jsonrpc.org/specification
*
* code message meaning
* -32700 Parse error Invalid JSON was received by the server.
* An error occurred on the server while parsing the JSON text.
* -32600 Invalid Request The JSON sent is not a valid Request object.
* -32601 Method not found The method does not exist / is not available.
* -32602 Invalid paramsInvalid method parameter(s).
* -32603 Internal errorInternal JSON-RPC error.
* -32000 to -32099Server error Reserved for implementation-defined server-errors.
*/
#define JRPC_PARSE_ERROR -32700
#define JRPC_INVALID_REQUEST -32600
#define JRPC_METHOD_NOT_FOUND -32601
#define JRPC_INVALID_PARAMS -32603
#define JRPC_INTERNAL_ERROR -32693
typedef struct {
void * data;
int error_code;
char * error_message ;
} jrpc_context;
//JSON方法类型
typedef cJSON*
(* jrpc_function )(jrpc_context *context, cJSON *params, cJSON*
id);
struct jrpc_procedure {
char * name;
//方法名
jrpc_function function;
//方法地址
void * data;
//额外信息
};
struct jrpc_server {
int port_number;
struct ev_loop
* loop; //eventloop类型
ev_io listen_watcher ;
//
int procedure_count;
struct jrpc_procedure
* procedures ;
int debug_level;
};
struct jrpc_connection {
struct ev_io io;
int fd;
int pos; //记录在buffer中的位置
unsigned int buffer_size ;
char * buffer;
int debug_level;
};
int jrpc_server_init( struct jrpc_server
*server, int port_number);
int jrpc_server_init_with_ev_loop( struct jrpc_server
*server,
int port_number, struct ev_loop
*loop);
static int __jrpc_server_start (struct jrpc_server
*server);
void jrpc_server_run( struct jrpc_server
*server);
int jrpc_server_stop( struct jrpc_server
*server);
void jrpc_server_destroy( struct jrpc_server
*server);
static void jrpc_procedure_destroy (struct jrpc_procedure
*procedure);
int jrpc_register_procedure( struct jrpc_server
*server,
jrpc_function function_pointer, char *name, void *data);
int jrpc_deregister_procedure( struct jrpc_server
*server, char *name);
#endif
-----------------json-rpc.c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include "jsonrpc-c.h"
struct ev_loop *loop;
// get sockaddr, IPv4 or IPv6:
static void *get_in_addr( struct sockaddr
*sa) {
if (sa-> sa_family == AF_INET)
{
return &(((struct sockaddr_in*)
sa)->sin_addr );
}
return &((( struct sockaddr_in6*)
sa)->sin6_addr);
}
static int send_response( struct jrpc_connection
* conn, char *response) {
int fd
= conn-> fd;
if (conn-> debug_level >
1)
printf ("JSON
Response:
%s
" , response);
write(fd,
response, strlen (response));
write(fd, "
" ,
1);
return 0;
}
static int send_error( struct jrpc_connection
* conn, int code, char *
message,
cJSON * id) {
int return_value
= 0;
cJSON *result_root = cJSON_CreateObject();
cJSON *error_root = cJSON_CreateObject();
cJSON_AddNumberToObject(error_root, "code" ,
code);
cJSON_AddStringToObject(error_root, "message" ,
message);
cJSON_AddItemToObject(result_root, "error" ,
error_root);
cJSON_AddItemToObject(result_root, "id" ,
id);
char *
str_result = cJSON_Print(result_root);
return_value = send_response(conn, str_result);
free(str_result);
cJSON_Delete(result_root);
free(message);
return return_value;
}
static int send_result( struct jrpc_connection
* conn, cJSON * result,
cJSON * id) {
int return_value
= 0;
cJSON *result_root = cJSON_CreateObject();
if (result)
cJSON_AddItemToObject(result_root, "result" ,
result);
cJSON_AddItemToObject(result_root, "id" ,
id);
char *
str_result = cJSON_Print(result_root);
return_value = send_response(conn, str_result);
free(str_result);
cJSON_Delete(result_root);
return return_value;
}
static int invoke_procedure( struct jrpc_server
*server,
struct jrpc_connection
* conn, char *name, cJSON *params, cJSON *id)
{
cJSON *returned = NULL;
int procedure_found
= 0;
jrpc_context ctx;
ctx. error_code =
0;
ctx. error_message =
NULL;
int i
= server-> procedure_count ;
while (i--)
{
if (!strcmp (server-> procedures[i]. name,
name)) {
procedure_found = 1;
ctx. data =
server-> procedures [i].data ;
returned = server->procedures [i].function (&ctx,
params, id);
break ;
}
}
if (!procedure_found)
return send_error(conn, JRPC_METHOD_NOT_FOUND,
strdup ("Method
not found." ), id);
else {
if (ctx.error_code )
return send_error(conn,
ctx.error_code , ctx.error_message ,
id);
else
return send_result(conn,
returned, id);
}
}
static int eval_request (struct jrpc_server
*server,
struct jrpc_connection
* conn, cJSON *root) {
cJSON *method, *params, *id;
method = cJSON_GetObjectItem(root, "method" );
if (method
!= NULL && method-> type == cJSON_String ) {
params = cJSON_GetObjectItem(root, "params ");
if (params
== NULL|| params->type == cJSON_Array
|| params-> type == cJSON_Object )
{
id = cJSON_GetObjectItem(root, "id" );
if (id
== NULL|| id->type == cJSON_String
|| id-> type == cJSON_Number )
{
//We have to copy ID because using
it on the reply and deleting the response Object will also delete ID
cJSON * id_copy = NULL;
if (id
!= NULL)
id_copy =
(id-> type == cJSON_String)
? cJSON_CreateString(
id-> valuestring) :
cJSON_CreateNumber(id-> valueint);
if (server->debug_level )
printf ("Method
Invoked: %s
" , method->valuestring);
return invoke_procedure(server,
conn, method->valuestring,
params, id_copy);
}
}
}
send_error(conn, JRPC_INVALID_REQUEST,
strdup ("The
JSON sent is not a valid Request object."), NULL);
return -1;
}
static void close_connection( struct ev_loop
*loop, ev_io *w) {
ev_io_stop(loop, w);
close((( struct jrpc_connection
*) w)->fd );
free((( struct jrpc_connection
*) w)->buffer );
free((( struct jrpc_connection
*) w));
}
static void connection_cb( struct ev_loop
*loop, ev_io *w, int revents)
{
struct jrpc_connection
*conn;
struct jrpc_server
*server = ( struct jrpc_server *) w->data;
size_t bytes_read
= 0;
//get our 'subclassed'
event watcher
conn = ( struct jrpc_connection
*) w;
int fd
= conn-> fd;
// 为这个session 分配的buffer满了，须要又一次分配空间，成倍增长
if (conn-> pos ==
(conn-> buffer_size - 1)) {
char *
new_buffer = realloc(conn-> buffer,
conn->buffer_size *= 2);
if (new_buffer
== NULL) {
perror ("Memory
error" );
return close_connection(loop,
w);
}
conn-> buffer =
new_buffer;
//把后来增长的空间置空
memset (conn->buffer +
conn-> pos, 0, conn->buffer_size -
conn->pos );
}
// can not fill the entire buffer, string must
be NULL terminated
int max_read_size
= conn-> buffer_size - conn->pos -
1;
//从套接字中读取数据。-1 说明异常终止
if ((bytes_read
= read (fd, conn->buffer +
conn-> pos, max_read_size))
== -1) {
perror ("read" );
return close_connection(loop,
w);
}
//为0说明client关闭连接
if (!bytes_read)
{
// client closed the sending half of the
connection
if (server->debug_level )
printf ("Client
closed connection.
" );
return close_connection(loop,
w);
} else {
cJSON *root;
char *end_ptr
= NULL;
conn-> pos +=
bytes_read;
if ((root
= cJSON_Parse_Stream(conn->buffer , &end_ptr)) != NULL)
{
if (server->debug_level >
1) {
char *
str_result = cJSON_Print(root);
printf ("Valid
JSON Received:
%s
" , str_result);
free (str_result);
}
if (root->type == cJSON_Object)
{
eval_request(server, conn, root);
}
//shift processed request, discarding
it
memmove (conn->buffer ,
end_ptr, strlen (end_ptr) + 2);
conn-> pos = strlen (end_ptr);
memset (conn->buffer +
conn-> pos, 0,
conn-> buffer_size -
conn->pos - 1);
cJSON_Delete(root);
} else {
// did we parse the all buffer?
If so, just wait for more.
// else there was an error before the
buffer's end
if (end_ptr
!= (conn->buffer + conn-> pos))
{
if (server->debug_level )
{
printf ("INVALID
JSON Received:
---
%s
---
",
conn-> buffer);
}
send_error(conn, JRPC_PARSE_ERROR,
strdup (
"Parse error.
Invalid JSON was received by the server."),
NULL);
return close_connection(loop,
w);
}
}
}
}
static void accept_cb( struct ev_loop
*loop, ev_io *w, int revents)
{
char s[ INET6_ADDRSTRLEN];
struct jrpc_connection
*connection_watcher;
connection_watcher = malloc (sizeof ( struct jrpc_connection));
//通用socket addr
struct sockaddr_storage
their_addr; // connector's address information
socklen_t sin_size;
sin_size = sizeof their_addr;
connection_watcher-> fd =
accept(w-> fd, ( struct sockaddr
*) &their_addr,
&sin_size);
if (connection_watcher-> fd ==
-1) {
perror ("accept" );
free (connection_watcher);
} else {
if (((struct jrpc_server
*) w->data)-> debug_level)
{
inet_ntop(their_addr. ss_family ,
get_in_addr(( struct sockaddr
*) &their_addr), s, sizeof s);
printf ("server:
got connection from %s
" , s);
}
ev_io_init(&connection_watcher-> io,
connection_cb,
connection_watcher-> fd, EV_READ);
//copy pointer to struct jrpc_server
connection_watcher-> io. data =
w->data ;
connection_watcher-> buffer_size =
1500;
connection_watcher-> buffer = malloc (1500);
memset (connection_watcher->buffer ,
0, 1500);
connection_watcher-> pos =
0;
//copy debug_level, struct jrpc_connection
has no pointer to struct jrpc_server
connection_watcher-> debug_level =
(( struct jrpc_server
*) w->data)-> debug_level;
ev_io_start(loop, &connection_watcher-> io);
}
}
int jrpc_server_init( struct jrpc_server
*server, int port_number) {
loop = EV_DEFAULT;
return jrpc_server_init_with_ev_loop(server,
port_number, loop);
}
int jrpc_server_init_with_ev_loop( struct jrpc_server
*server,
int port_number, struct ev_loop
*loop) {
memset(server,
0, sizeof (struct jrpc_server));
server-> loop =
loop;
server-> port_number =
port_number;
char *
debug_level_env = getenv ("JRPC_DEBUG" );
if (debug_level_env
== NULL)
server-> debug_level =
0;
else {
server-> debug_level = strtol (debug_level_env,
NULL, 10);
printf ("JSONRPC-C
Debug level %d
" , server->debug_level );
}
return __jrpc_server_start(server);
}
static int __jrpc_server_start (struct jrpc_server
*server) {
int sockfd;
struct addrinfo
hints, *servinfo, *p;
struct sockaddr_in
sockaddr;
int len;
int yes
= 1;
int rv;
char PORT[6];
sprintf(PORT, "%d" ,
server->port_number );
memset(&hints,
0, sizeof hints);
hints. ai_family = AF_UNSPEC;
hints. ai_socktype = SOCK_STREAM;
hints. ai_flags = AI_PASSIVE; //
use my IP
if ((rv
= getaddrinfo(NULL, PORT, &hints, &servinfo)) != 0) {
fprintf (stderr, " getaddrinfo:
%s
" , gai_strerror(rv));
return 1;
}
// loop through all the results and bind to the first we can
for (p
= servinfo; p != NULL; p = p-> ai_next) {
if ((sockfd
= socket(p->ai_family , p->ai_socktype ,
p->ai_protocol ))
== -1) {
perror ("server:
socket" );
continue ;
}
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
&yes, sizeof (int ))
== -1) {
perror (" setsockopt" );
exit (1);
}
if (bind(sockfd,
p->ai_addr , p->ai_addrlen )
== -1) {
close (sockfd);
perror ("server:
bind" );
continue ;
}
len = sizeof (sockaddr);
if (getsockname(sockfd,
( struct sockaddr *) &sockaddr, &len)
== -1) {
close (sockfd);
perror ("server: getsockname" );
continue ;
}
server-> port_number =
ntohs( sockaddr.sin_port );
break ;
}
if (p
== NULL) {
fprintf (stderr, "server:
failed to bind
" );
return 2;
}
freeaddrinfo(servinfo); // all done with this
structure
if (listen(sockfd,
5) == -1) {
perror ("listen" );
exit (1);
}
if (server-> debug_level )
printf ("server:
waiting for connections...
" );
ev_io_init(&server-> listen_watcher ,
accept_cb, sockfd, EV_READ);
server-> listen_watcher .data =
server;
ev_io_start(server-> loop,
&server-> listen_watcher );
return 0;
}
// Make the code work with both the old (ev_loop/ev_unloop)
// and new (ev_run/ev_break) versions of libev.
#ifdef EVUNLOOP_ALL
#define EV_RUN
ev_loop
#define EV_BREAK
ev_unloop
#define EVBREAK_ALL
EVUNLOOP_ALL
#else
#define EV_RUN
ev_run
#define EV_BREAK
ev_break
#endif
void jrpc_server_run( struct jrpc_server
*server){
EV_RUN(server-> loop,
0);
}
int jrpc_server_stop( struct jrpc_server
*server) {
EV_BREAK(server-> loop, EVBREAK_ALL);
return 0;
}
void jrpc_server_destroy( struct jrpc_server
*server){
/* Don't destroy server */
int i;
for (i
= 0; i < server-> procedure_count ; i++){
jrpc_procedure_destroy( &(server-> procedures [i])
);
}
free(server-> procedures );
}
static void jrpc_procedure_destroy (struct jrpc_procedure
*procedure){
if (procedure-> name){
free (procedure->name );
procedure-> name =
NULL;
}
if (procedure-> data){
free (procedure->data );
procedure-> data =
NULL;
}
}
int jrpc_register_procedure( struct jrpc_server
*server,
jrpc_function function_pointer, char *name, void *
data) {
int i
= server-> procedure_count ++;
if (!server-> procedures )
server-> procedures = malloc ( sizeof( struct jrpc_procedure));
else {
//每次添加一个jrpc_procedure空间
struct jrpc_procedure
* ptr = realloc (server->procedures ,
sizeof (struct jrpc_procedure)
* server->procedure_count );
if (!ptr)
return -1;
server-> procedures =
ptr;
}
//name是局部变量，所以要 strdup
if ((server-> procedures [i].name = strdup(name))
== NULL)
return -1;
server-> procedures [i].function =
function_pointer;
server-> procedures [i].data =
data;
return 0;
}
int jrpc_deregister_procedure( struct jrpc_server
*server, char *name) {
/* Search the procedure to deregister */
int i;
int found
= 0;
if (server-> procedures ){
for (i
= 0; i < server->procedure_count ; i++){
if (found)
server-> procedures [i-1]
= server->procedures [i];
else if (! strcmp(name,
server->procedures [i].name )){
found = 1;
jrpc_procedure_destroy( &(server->procedures [i])
);
}
}
if (found){
server-> procedure_count --;
if (server->procedure_count ){
struct jrpc_procedure
* ptr = realloc (server->procedures ,
sizeof (struct jrpc_procedure)
* server->procedure_count );
if (!ptr){
perror (" realloc" );
return -1;
}
server-> procedures =
ptr;
} else {
server-> procedures =
NULL;
}
}
} else {
fprintf (stderr, "server
: procedure '%s' not found
", name);
return -1;
}
return 0;
}
----------当中关于cJSON代码部分。见 C语言解析JSON部分。
參考：