gdb-server/client.c

#include <client.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>

static bool write_char(RdbClient *self, char out)  {
    if (self->len >= RDB_CLIENT_BUFLEN) {
        return false;
    }
    if (out == '#' || out == '$' || out == '}' || out == '*') {
        self->full_buf[self->len++] = '}';
        self->chk += '}';
        if (self->len >= RDB_CLIENT_BUFLEN) {
            return false;
        }
        out ^= 0x20;
    }
    self->full_buf[self->len++] = out;
    self->chk += out;
    return true;
}

bool char_to_hex_digit(char in, char *out) {
    if (in & 0xf0) {
        return false;
    }
    in &= 0x0f;
    if (in > 9) {
        *out = 'a' + in - 10;
    } else {
        *out = '0' + in;
    }
    return true;
}

bool char_to_hex_digits(char in, char *hi, char *lo) {
    return char_to_hex_digit((in & 0xf0) >> 4, hi)
        && char_to_hex_digit(in & 0x0f, lo);
}

void rdb_client_init(RdbClient *self, int connfd) {
    self->connfd = connfd;
    self->len = 0;
    self->chk = 0;
    self->should_ack = true;
}

void rdb_client_begin_packet(RdbClient *self) {
    self->len = 0;
    self->chk = 0;
    if (self->should_ack) {
        self->full_buf[self->len++] = '+';
    }
    self->full_buf[self->len++] = '$';
}

bool rdb_client_write_str(RdbClient *self, const char *str) {
    size_t len = strlen(str);
    for (size_t i = 0; i < len; ++i) {
        if (!write_char(self, str[i])) {
            return false;
        }
    }
    return true;
}

bool rdb_client_write_str_hex(RdbClient *self, const char *str) {
    size_t len = strlen(str);
    for (size_t i = 0; i < len; ++i) {
        char hi, lo;
        if (!char_to_hex_digits(str[i], &hi, &lo)
            || !write_char(self, hi)
            || !write_char(self, lo)) {
                return false;
        }
    }
    return true;
}

bool rdb_client_write_i8_hex(RdbClient *self, uint8_t value) {
    char hi, lo;
    return char_to_hex_digits(value, &hi, &lo)
        && write_char(self, hi)
        && write_char(self, lo);
}

bool rdb_client_write_i32_hex(RdbClient *self, uint32_t value) {
    return rdb_client_write_i8_hex(self, (uint8_t) value)
        && rdb_client_write_i8_hex(self, (uint8_t) (value >> 8))
        && rdb_client_write_i8_hex(self, (uint8_t) (value >> 16))
        && rdb_client_write_i8_hex(self, (uint8_t) (value >> 24));
}

int rdb_client_send_packet(RdbClient *self) {
    if (self->len + 3 > RDB_CLIENT_BUFLEN) {
        return -1;
    }
    self->full_buf[self->len++] = '#';
    char hi, lo;
    if (!char_to_hex_digits(self->chk, &hi, &lo)) {
        return -1;
    }
    self->full_buf[self->len++] = hi;
    self->full_buf[self->len++] = lo;
    printf("sending command \"%.*s\" %d\n", (int) self->len, self->full_buf, (int)self->len);

    ssize_t rwrite = write(self->connfd, self->full_buf, self->len);
    if (rwrite == -1) {
        return -1;
    }
    return 0;
}