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