source: lib/oauth.c @ c573f1b

/***************************************************************************\
*                                                                           *
*  BitlBee - An IRC to IM gateway                                           *
*  Simple OAuth client (consumer) implementation.                           *
*                                                                           *
*  Copyright 2010 Wilmer van der Gaast <wilmer@gaast.net>                   *
*                                                                           *
*  This library is free software; you can redistribute it and/or            *
*  modify it under the terms of the GNU Lesser General Public               *
*  License as published by the Free Software Foundation, version            *
*  2.1.                                                                     *
*                                                                           *
*  This library is distributed in the hope that it will be useful,          *
*  but WITHOUT ANY WARRANTY; without even the implied warranty of           *
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU        *
*  Lesser General Public License for more details.                          *
*                                                                           *
*  You should have received a copy of the GNU Lesser General Public License *
*  along with this library; if not, write to the Free Software Foundation,  *
*  Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA           *
*                                                                           *
\***************************************************************************/

#include <glib.h>
#include <gmodule.h>
#include <stdlib.h>
#include <string.h>
#include "http_client.h"
#include "base64.h"
#include "misc.h"
#include "sha1.h"
#include "url.h"
#include "oauth.h"

#define HMAC_BLOCK_SIZE 64

static char *oauth_sign( const char *method, const char *url,
                         const char *params, struct oauth_info *oi )
{
        sha1_state_t sha1;
        uint8_t hash[sha1_hash_size];
        uint8_t key[HMAC_BLOCK_SIZE+1];
        char *s;
        int i;
        
        /* Create K. If our current key is >64 chars we have to hash it,
           otherwise just pad. */
        memset( key, 0, HMAC_BLOCK_SIZE );
        i = strlen( oi->sp->consumer_secret ) + 1 + ( oi->token_secret ? strlen( oi->token_secret ) : 0 );
        if( i > HMAC_BLOCK_SIZE )
        {
                sha1_init( &sha1 );
                sha1_append( &sha1, (uint8_t*) oi->sp->consumer_secret, strlen( oi->sp->consumer_secret ) );
                sha1_append( &sha1, (uint8_t*) "&", 1 );
                if( oi->token_secret )
                        sha1_append( &sha1, (uint8_t*) oi->token_secret, strlen( oi->token_secret ) );
                sha1_finish( &sha1, key );
        }
        else
        {
                g_snprintf( (gchar*) key, HMAC_BLOCK_SIZE + 1, "%s&%s",
                            oi->sp->consumer_secret, oi->token_secret ? oi->token_secret : "" );
        }
        
        /* Inner part: H(K XOR 0x36, text) */
        sha1_init( &sha1 );
        
        for( i = 0; i < HMAC_BLOCK_SIZE; i ++ )
                key[i] ^= 0x36;
        sha1_append( &sha1, key, HMAC_BLOCK_SIZE );
        
        /* OAuth: text = method&url&params, all http_encoded. */
        sha1_append( &sha1, (const uint8_t*) method, strlen( method ) );
        sha1_append( &sha1, (const uint8_t*) "&", 1 );
        
        s = g_new0( char, strlen( url ) * 3 + 1 );
        strcpy( s, url );
        http_encode( s );
        sha1_append( &sha1, (const uint8_t*) s, strlen( s ) );
        sha1_append( &sha1, (const uint8_t*) "&", 1 );
        g_free( s );
        
        s = g_new0( char, strlen( params ) * 3 + 1 );
        strcpy( s, params );
        http_encode( s );
        sha1_append( &sha1, (const uint8_t*) s, strlen( s ) );
        g_free( s );
        
        sha1_finish( &sha1, hash );
        
        /* Final result: H(K XOR 0x5C, inner stuff) */
        sha1_init( &sha1 );
        for( i = 0; i < HMAC_BLOCK_SIZE; i ++ )
                key[i] ^= 0x36 ^ 0x5c;
        sha1_append( &sha1, key, HMAC_BLOCK_SIZE );
        sha1_append( &sha1, hash, sha1_hash_size );
        sha1_finish( &sha1, hash );
        
        /* base64_encode + HTTP escape it (both consumers 
           need it that away) and we're done. */
        s = base64_encode( hash, sha1_hash_size );
        s = g_realloc( s, strlen( s ) * 3 + 1 );
        http_encode( s );
        
        return s;
}

static char *oauth_nonce()
{
        unsigned char bytes[21];
        char *ret = g_new0( char, sizeof( bytes) / 3 * 4 + 1 );
        
        random_bytes( bytes, sizeof( bytes ) );
        base64_encode_real( bytes, sizeof( bytes), (unsigned char*) ret, "0123456789"
                            "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0A" );
        
        return ret;
}

void oauth_params_add( GSList **params, const char *key, const char *value )
{
        char *item;
        
        item = g_strdup_printf( "%s=%s", key, value );
        *params = g_slist_insert_sorted( *params, item, (GCompareFunc) strcmp );
}

void oauth_params_del( GSList **params, const char *key )
{
        int key_len = strlen( key );
        GSList *l, *n;
        
        for( l = *params; l; l = n )
        {
                n = l->next;
                
                if( strncmp( (char*) l->data, key, key_len ) == 0 &&
                    ((char*)l->data)[key_len] == '=' )
                {
                        g_free( l->data );
                        *params = g_slist_remove( *params, l->data );
                }
        }
}

void oauth_params_set( GSList **params, const char *key, const char *value )
{
        oauth_params_del( params, key );
        oauth_params_add( params, key, value );
}

const char *oauth_params_get( GSList **params, const char *key )
{
        int key_len = strlen( key );
        GSList *l;
        
        for( l = *params; l; l = l->next )
        {
                if( strncmp( (char*) l->data, key, key_len ) == 0 &&
                    ((char*)l->data)[key_len] == '=' )
                        return (const char*) l->data + key_len + 1;
        }
        
        return NULL;
}

static void oauth_params_parse( GSList **params, char *in )
{
        char *amp, *eq, *s;
        
        while( in && *in )
        {
                eq = strchr( in, '=' );
                if( !eq )
                        break;
                
                *eq = '\0';
                if( ( amp = strchr( eq + 1, '&' ) ) )
                        *amp = '\0';
                
                s = g_strdup( eq + 1 );
                http_decode( s );
                oauth_params_add( params, in, s );
                g_free( s );
                
                *eq = '=';
                if( amp == NULL )
                        break;
                
                *amp = '&';
                in = amp + 1;
        }
}

void oauth_params_free( GSList **params )
{
        while( params && *params )
        {
                g_free( (*params)->data );
                *params = g_slist_remove( *params, (*params)->data );
        }
}

char *oauth_params_string( GSList *params )
{
        GSList *l;
        GString *str = g_string_new( "" );
        
        for( l = params; l; l = l->next )
        {
                char *s, *eq;
                
                s = g_malloc( strlen( l->data ) * 3 + 1 );
                strcpy( s, l->data );
                if( ( eq = strchr( s, '=' ) ) )
                        http_encode( eq + 1 );
                g_string_append( str, s );
                g_free( s );
                
                if( l->next )
                        g_string_append_c( str, '&' );
        }
        
        return g_string_free( str, FALSE );
}

void oauth_info_free( struct oauth_info *info )
{
        if( info )
        {
                g_free( info->auth_url );
                g_free( info->request_token );
                g_free( info->token );
                g_free( info->token_secret );
                oauth_params_free( &info->params );
                g_free( info );
        }
}

static void oauth_add_default_params( GSList **params, const struct oauth_service *sp )
{
        char *s;
        
        oauth_params_set( params, "oauth_consumer_key", sp->consumer_key );
        oauth_params_set( params, "oauth_signature_method", "HMAC-SHA1" );
        
        s = g_strdup_printf( "%d", (int) time( NULL ) );
        oauth_params_set( params, "oauth_timestamp", s );
        g_free( s );
        
        s = oauth_nonce();
        oauth_params_set( params, "oauth_nonce", s );
        g_free( s );
        
        oauth_params_set( params, "oauth_version", "1.0" );
}

static void *oauth_post_request( const char *url, GSList **params_, http_input_function func, struct oauth_info *oi )
{
        GSList *params = NULL;
        char *s, *params_s, *post;
        void *req;
        url_t url_p;
        
        if( !url_set( &url_p, url ) )
        {
                oauth_params_free( params_ );
                return NULL;
        }
        
        if( params_ )
                params = *params_;
        
        oauth_add_default_params( &params, oi->sp );
        
        params_s = oauth_params_string( params );
        oauth_params_free( &params );
        
        s = oauth_sign( "POST", url, params_s, oi );
        post = g_strdup_printf( "%s&oauth_signature=%s", params_s, s );
        g_free( params_s );
        g_free( s );
        
        s = g_strdup_printf( "POST %s HTTP/1.0\r\n"
                             "Host: %s\r\n"
                             "Content-Type: application/x-www-form-urlencoded\r\n"
                             "Content-Length: %zd\r\n"
                             "\r\n"
                             "%s", url_p.file, url_p.host, strlen( post ), post );
        g_free( post );
        
        req = http_dorequest( url_p.host, url_p.port, url_p.proto == PROTO_HTTPS,
                              s, func, oi );
        g_free( s );
        
        return req;
}

static void oauth_request_token_done( struct http_request *req );

struct oauth_info *oauth_request_token( const struct oauth_service *sp, oauth_cb func, void *data )
{
        struct oauth_info *st = g_new0( struct oauth_info, 1 );
        GSList *params = NULL;
        
        st->func = func;
        st->data = data;
        st->sp = sp;
        
        oauth_params_add( &params, "oauth_callback", "oob" );
        
        if( !oauth_post_request( sp->url_request_token, &params, oauth_request_token_done, st ) )
        {
                oauth_info_free( st );
                return NULL;
        }
        
        return st;
}

static void oauth_request_token_done( struct http_request *req )
{
        struct oauth_info *st = req->data;
        
        st->http = req;
        
        if( req->status_code == 200 )
        {
                GSList *params = NULL;
                
                st->auth_url = g_strdup_printf( "%s?%s", st->sp->url_authorize, req->reply_body );
                oauth_params_parse( &params, req->reply_body );
                st->request_token = g_strdup( oauth_params_get( &params, "oauth_token" ) );
                oauth_params_free( &params );
        }
        
        st->stage = OAUTH_REQUEST_TOKEN;
        st->func( st );
}

static void oauth_access_token_done( struct http_request *req );

gboolean oauth_access_token( const char *pin, struct oauth_info *st )
{
        GSList *params = NULL;
        
        oauth_params_add( &params, "oauth_token", st->request_token );
        oauth_params_add( &params, "oauth_verifier", pin );
        
        return oauth_post_request( st->sp->url_access_token, &params, oauth_access_token_done, st ) != NULL;
}

static void oauth_access_token_done( struct http_request *req )
{
        struct oauth_info *st = req->data;
        
        st->http = req;
        
        if( req->status_code == 200 )
        {
                oauth_params_parse( &st->params, req->reply_body );
                st->token = g_strdup( oauth_params_get( &st->params, "oauth_token" ) );
                st->token_secret = g_strdup( oauth_params_get( &st->params, "oauth_token_secret" ) );
        }
        
        st->stage = OAUTH_ACCESS_TOKEN;
        if( st->func( st ) )
        {
                /* Don't need these anymore, but keep the rest. */
                g_free( st->auth_url );
                st->auth_url = NULL;
                g_free( st->request_token );
                st->request_token = NULL;
                oauth_params_free( &st->params );
        }
}

char *oauth_http_header( struct oauth_info *oi, const char *method, const char *url, char *args )
{
        GSList *params = NULL, *l;
        char *sig = NULL, *params_s, *s;
        GString *ret = NULL;
        
        oauth_params_add( &params, "oauth_token", oi->token );
        oauth_add_default_params( &params, oi->sp );
        
        /* Start building the OAuth header. 'key="value", '... */
        ret = g_string_new( "OAuth " );
        for( l = params; l; l = l->next )
        {
                char *kv = l->data;
                char *eq = strchr( kv, '=' );
                char esc[strlen(kv)*3+1];
                
                if( eq == NULL )
                        break; /* WTF */
                
                strcpy( esc, eq + 1 );
                http_encode( esc );
                
                g_string_append_len( ret, kv, eq - kv + 1 );
                g_string_append_c( ret, '"' );
                g_string_append( ret, esc );
                g_string_append( ret, "\", " );
        }
        
        /* Now, before generating the signature, add GET/POST arguments to params
           since they should be included in the base signature string (but not in
           the HTTP header). */
        if( args )
                oauth_params_parse( &params, args );
        if( ( s = strchr( url, '?' ) ) )
        {
                s = g_strdup( s + 1 );
                oauth_params_parse( &params, s );
                g_free( s );
        }
        
        /* Append the signature and we're done! */
        params_s = oauth_params_string( params );
        sig = oauth_sign( method, url, params_s, oi );
        g_string_append_printf( ret, "oauth_signature=\"%s\"", sig );
        g_free( params_s );
        
        oauth_params_free( &params );
        g_free( sig );
        
        return ret ? g_string_free( ret, FALSE ) : NULL;
}

char *oauth_to_string( struct oauth_info *oi )
{
        GSList *params = NULL;
        char *ret;
        
        oauth_params_add( &params, "oauth_token", oi->token );
        oauth_params_add( &params, "oauth_token_secret", oi->token_secret );
        ret = oauth_params_string( params );
        oauth_params_free( &params );
        
        return ret;
}

struct oauth_info *oauth_from_string( char *in, const struct oauth_service *sp )
{
        struct oauth_info *oi = g_new0( struct oauth_info, 1 );
        GSList *params = NULL;
        
        oauth_params_parse( &params, in );
        oi->token = g_strdup( oauth_params_get( &params, "oauth_token" ) );
        oi->token_secret = g_strdup( oauth_params_get( &params, "oauth_token_secret" ) );
        oauth_params_free( &params );
        oi->sp = sp;
        
        return oi;
}