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