c-libp2p/net/multistream.c
2017-02-09 03:34:12 -05:00

137 lines
3.5 KiB
C

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include "libp2p/net/p2pnet.h"
#include "varint.h"
/***
* An implementation of the libp2p multistream
*/
/**
* Write to an open multistream host
* @param socket_fd the socket file descriptor
* @param data the data to send
* @param data_length the length of the data
* @returns the number of bytes written
*/
int libp2p_net_multistream_send(int socket_fd, const unsigned char* data, size_t data_length) {
int num_bytes = 0;
if (data_length > 0) { // only do this is if there is something to send
// first send the size
unsigned char varint[12];
size_t varint_size = 0;
varint_encode(data_length, &varint[0], 12, &varint_size);
num_bytes = socket_write(socket_fd, (char*)varint, varint_size, 0);
if (num_bytes == 0)
return 0;
// then send the actual data
num_bytes += socket_write(socket_fd, (char*)data, data_length, 0);
}
return num_bytes;
}
/**
* Read from a multistream socket
* @param socket_fd the socket file descriptor
* @param results where to put the results. NOTE: this memory is allocated
* @param results_size the size of the results in bytes
* @returns number of bytes received
*/
int libp2p_net_multistream_receive(int socket_fd, char** results, size_t* results_size) {
int bytes = 0;
size_t buffer_size = 65535;
char buffer[buffer_size];
char* pos = buffer;
size_t num_bytes_requested = 0, left = 0, already_read = 0;
// first read the varint
while(1) {
unsigned char c;
bytes = socket_read(socket_fd, (char*)&c, 1, 0);
pos[0] = c;
if (c >> 7 == 0) {
pos[1] = 0;
num_bytes_requested = varint_decode((unsigned char*)buffer, strlen(buffer), NULL);
break;
}
pos++;
}
if (num_bytes_requested <= 0)
return 0;
left = num_bytes_requested;
do {
bytes = socket_read(socket_fd, &buffer[already_read], left, 0);
if (bytes < 0) {
bytes = 0;
if ( (errno == EAGAIN) || (errno == EWOULDBLOCK)) {
// do something intelligent
} else {
return 0;
}
}
left = left - bytes;
already_read += bytes;
} while (left > 0);
if (already_read != num_bytes_requested)
return 0;
// parse the results, removing the leading size indicator
*results = malloc(num_bytes_requested);
if (*results == NULL)
return 0;
memcpy(*results, buffer, num_bytes_requested);
*results_size = num_bytes_requested;
return num_bytes_requested;
}
/**
* Connect to a multistream host, and this includes the multistream handshaking.
* @param hostname the host
* @param port the port
* @returns the socket file descriptor of the connection, or -1 on error
*/
int libp2p_net_multistream_connect(const char* hostname, int port) {
int retVal = -1, return_result = -1, socket = -1;
char* results = NULL;
size_t results_size;
size_t num_bytes = 0;
uint32_t ip = hostname_to_ip(hostname);
socket = socket_open4();
// connect
if (socket_connect4(socket, ip, port) != 0)
goto exit;
// send the multistream handshake
char* protocol_buffer = "/multistream/1.0.0\n";
num_bytes = libp2p_net_multistream_send(socket, (unsigned char*)protocol_buffer, strlen(protocol_buffer));
if (num_bytes <= 0)
goto exit;
// try to receive the protocol id
return_result = libp2p_net_multistream_receive(socket, &results, &results_size);
if (return_result == 0 || results_size < 1)
goto exit;
if (strstr(results, "multistream") == NULL)
goto exit;
// we are now in the loop, so we can switch to another protocol (i.e. /secio/1.0.0)
retVal = socket;
exit:
if (results != NULL)
free(results);
return retVal;
}