serve.c

   1 #include "cache.h"
   2 #include "repository.h"
   3 #include "config.h"
   4 #include "pkt-line.h"
   5 #include "version.h"
   6 #include "strvec.h"
   7 #include "ls-refs.h"
   8 #include "serve.h"
   9 #include "upload-pack.h"
  10
  11 static int advertise_sid;
  12
  13 static int always_advertise(struct repository *r,
  14                             struct strbuf *value)
  15 {
  16         return 1;
  17 }
  18
  19 static int agent_advertise(struct repository *r,
  20                            struct strbuf *value)
  21 {
  22         if (value)
  23                 strbuf_addstr(value, git_user_agent_sanitized());
  24         return 1;
  25 }
  26
  27 static int object_format_advertise(struct repository *r,
  28                                    struct strbuf *value)
  29 {
  30         if (value)
  31                 strbuf_addstr(value, r->hash_algo->name);
  32         return 1;
  33 }
  34
  35 static int session_id_advertise(struct repository *r, struct strbuf *value)
  36 {
  37         if (!advertise_sid)
  38                 return 0;
  39         if (value)
  40                 strbuf_addstr(value, trace2_session_id());
  41         return 1;
  42 }
  43
  44 struct protocol_capability {
  45         /*
  46          * The name of the capability.  The server uses this name when
  47          * advertising this capability, and the client uses this name to
  48          * specify this capability.
  49          */
  50         const char *name;
  51
  52         /*
  53          * Function queried to see if a capability should be advertised.
  54          * Optionally a value can be specified by adding it to 'value'.
  55          * If a value is added to 'value', the server will advertise this
  56          * capability as "<name>=<value>" instead of "<name>".
  57          */
  58         int (*advertise)(struct repository *r, struct strbuf *value);
  59
  60         /*
  61          * Function called when a client requests the capability as a command.
  62          * The function will be provided the capabilities requested via 'keys'
  63          * as well as a struct packet_reader 'request' which the command should
  64          * use to read the command specific part of the request.  Every command
  65          * MUST read until a flush packet is seen before sending a response.
  66          *
  67          * This field should be NULL for capabilities which are not commands.
  68          */
  69         int (*command)(struct repository *r,
  70                        struct strvec *keys,
  71                        struct packet_reader *request);
  72 };
  73
  74 static struct protocol_capability capabilities[] = {
  75         { "agent", agent_advertise, NULL },
  76         { "ls-refs", ls_refs_advertise, ls_refs },
  77         { "fetch", upload_pack_advertise, upload_pack_v2 },
  78         { "server-option", always_advertise, NULL },
  79         { "object-format", object_format_advertise, NULL },
  80         { "session-id", session_id_advertise, NULL },
  81 };
  82
  83 static void advertise_capabilities(void)
  84 {
  85         struct strbuf capability = STRBUF_INIT;
  86         struct strbuf value = STRBUF_INIT;
  87         int i;
  88
  89         for (i = 0; i < ARRAY_SIZE(capabilities); i++) {
  90                 struct protocol_capability *c = &capabilities[i];
  91
  92                 if (c->advertise(the_repository, &value)) {
  93                         strbuf_addstr(&capability, c->name);
  94
  95                         if (value.len) {
  96                                 strbuf_addch(&capability, '=');
  97                                 strbuf_addbuf(&capability, &value);
  98                         }
  99
 100                         strbuf_addch(&capability, '\n');
 101                         packet_write(1, capability.buf, capability.len);
 102                 }
 103
 104                 strbuf_reset(&capability);
 105                 strbuf_reset(&value);
 106         }
 107
 108         packet_flush(1);
 109         strbuf_release(&capability);
 110         strbuf_release(&value);
 111 }
 112
 113 static struct protocol_capability *get_capability(const char *key)
 114 {
 115         int i;
 116
 117         if (!key)
 118                 return NULL;
 119
 120         for (i = 0; i < ARRAY_SIZE(capabilities); i++) {
 121                 struct protocol_capability *c = &capabilities[i];
 122                 const char *out;
 123                 if (skip_prefix(key, c->name, &out) && (!*out || *out == '='))
 124                         return c;
 125         }
 126
 127         return NULL;
 128 }
 129
 130 static int is_valid_capability(const char *key)
 131 {
 132         const struct protocol_capability *c = get_capability(key);
 133
 134         return c && c->advertise(the_repository, NULL);
 135 }
 136
 137 static int is_command(const char *key, struct protocol_capability **command)
 138 {
 139         const char *out;
 140
 141         if (skip_prefix(key, "command=", &out)) {
 142                 struct protocol_capability *cmd = get_capability(out);
 143
 144                 if (*command)
 145                         die("command '%s' requested after already requesting command '%s'",
 146                             out, (*command)->name);
 147                 if (!cmd || !cmd->advertise(the_repository, NULL) || !cmd->command)
 148                         die("invalid command '%s'", out);
 149
 150                 *command = cmd;
 151                 return 1;
 152         }
 153
 154         return 0;
 155 }
 156
 157 int has_capability(const struct strvec *keys, const char *capability,
 158                    const char **value)
 159 {
 160         int i;
 161         for (i = 0; i < keys->nr; i++) {
 162                 const char *out;
 163                 if (skip_prefix(keys->v[i], capability, &out) &&
 164                     (!*out || *out == '=')) {
 165                         if (value) {
 166                                 if (*out == '=')
 167                                         out++;
 168                                 *value = out;
 169                         }
 170                         return 1;
 171                 }
 172         }
 173
 174         return 0;
 175 }
 176
 177 static void check_algorithm(struct repository *r, struct strvec *keys)
 178 {
 179         int client = GIT_HASH_SHA1, server = hash_algo_by_ptr(r->hash_algo);
 180         const char *algo_name;
 181
 182         if (has_capability(keys, "object-format", &algo_name)) {
 183                 client = hash_algo_by_name(algo_name);
 184                 if (client == GIT_HASH_UNKNOWN)
 185                         die("unknown object format '%s'", algo_name);
 186         }
 187
 188         if (client != server)
 189                 die("mismatched object format: server %s; client %s\n",
 190                     r->hash_algo->name, hash_algos[client].name);
 191 }
 192
 193 enum request_state {
 194         PROCESS_REQUEST_KEYS,
 195         PROCESS_REQUEST_DONE,
 196 };
 197
 198 static int process_request(void)
 199 {
 200         enum request_state state = PROCESS_REQUEST_KEYS;
 201         struct packet_reader reader;
 202         struct strvec keys = STRVEC_INIT;
 203         struct protocol_capability *command = NULL;
 204         const char *client_sid;
 205
 206         packet_reader_init(&reader, 0, NULL, 0,
 207                            PACKET_READ_CHOMP_NEWLINE |
 208                            PACKET_READ_GENTLE_ON_EOF |
 209                            PACKET_READ_DIE_ON_ERR_PACKET);
 210
 211         /*
 212          * Check to see if the client closed their end before sending another
 213          * request.  If so we can terminate the connection.
 214          */
 215         if (packet_reader_peek(&reader) == PACKET_READ_EOF)
 216                 return 1;
 217         reader.options &= ~PACKET_READ_GENTLE_ON_EOF;
 218
 219         while (state != PROCESS_REQUEST_DONE) {
 220                 switch (packet_reader_peek(&reader)) {
 221                 case PACKET_READ_EOF:
 222                         BUG("Should have already died when seeing EOF");
 223                 case PACKET_READ_NORMAL:
 224                         /* collect request; a sequence of keys and values */
 225                         if (is_command(reader.line, &command) ||
 226                             is_valid_capability(reader.line))
 227                                 strvec_push(&keys, reader.line);
 228                         else
 229                                 die("unknown capability '%s'", reader.line);
 230
 231                         /* Consume the peeked line */
 232                         packet_reader_read(&reader);
 233                         break;
 234                 case PACKET_READ_FLUSH:
 235                         /*
 236                          * If no command and no keys were given then the client
 237                          * wanted to terminate the connection.
 238                          */
 239                         if (!keys.nr)
 240                                 return 1;
 241
 242                         /*
 243                          * The flush packet isn't consume here like it is in
 244                          * the other parts of this switch statement.  This is
 245                          * so that the command can read the flush packet and
 246                          * see the end of the request in the same way it would
 247                          * if command specific arguments were provided after a
 248                          * delim packet.
 249                          */
 250                         state = PROCESS_REQUEST_DONE;
 251                         break;
 252                 case PACKET_READ_DELIM:
 253                         /* Consume the peeked line */
 254                         packet_reader_read(&reader);
 255
 256                         state = PROCESS_REQUEST_DONE;
 257                         break;
 258                 case PACKET_READ_RESPONSE_END:
 259                         BUG("unexpected stateless separator packet");
 260                 }
 261         }
 262
 263         if (!command)
 264                 die("no command requested");
 265
 266         check_algorithm(the_repository, &keys);
 267
 268         if (has_capability(&keys, "session-id", &client_sid))
 269                 trace2_data_string("transfer", NULL, "client-sid", client_sid);
 270
 271         command->command(the_repository, &keys, &reader);
 272
 273         strvec_clear(&keys);
 274         return 0;
 275 }
 276
 277 /* Main serve loop for protocol version 2 */
 278 void serve(struct serve_options *options)
 279 {
 280         git_config_get_bool("transfer.advertisesid", &advertise_sid);
 281
 282         if (options->advertise_capabilities || !options->stateless_rpc) {
 283                 /* serve by default supports v2 */
 284                 packet_write_fmt(1, "version 2\n");
 285
 286                 advertise_capabilities();
 287                 /*
 288                  * If only the list of capabilities was requested exit
 289                  * immediately after advertising capabilities
 290                  */
 291                 if (options->advertise_capabilities)
 292                         return;
 293         }
 294
 295         /*
 296          * If stateless-rpc was requested then exit after
 297          * a single request/response exchange
 298          */
 299         if (options->stateless_rpc) {
 300                 process_request();
 301         } else {
 302                 for (;;)
 303                         if (process_request())
 304                                 break;
 305         }
 306 }