File content as of revision 40:84182fc63956:

#include "EthernetNetIf.h"
#include "SimpleSocket.h"
#include <ctype.h>

void encodeBase64(char *ibuf, char *obuf);
int encodeFormUrl(char *s, char *t);

void supertweet() {
    EthernetNetIf eth;
    eth.setup();
    ClientSocket client("66.180.175.246", 80); // api.supertweet.net

    char user[16], password[16], message[64] = {};
    printf("user => ");
    scanf("%s", user);
    printf("password => ");
    scanf("%s", password);
    printf("message => ");
    int c = 0;
    while (c < ' ' || 0x7E < c)
        c = getc(stdin);
    ungetc(c, stdin);
    for (int i = 0; i < sizeof(message) - 1 && (c = getc(stdin)) >= ' '; i++)
        message[i] = c;

    char credential[48], credential2[64], message2[256];

    sprintf(credential, "%s:%s", user, password);
    encodeBase64(credential, credential2);
    encodeFormUrl(message, message2);

    const char *request =
        "POST /1/statuses/update.xml HTTP/1.1\r\n"
        "Host: api.supertweet.net\r\n"
        "Authorization: Basic %s\r\n"
        "Content-Length: %d\r\n"
        "Content-Type: application/x-www-form-urlencoded\r\n"
        "\r\n"
        "status=%s";

    client.printf(request, credential2, strlen(message2) + 7,  message2);
    printf(request, credential2, strlen(message2) + 7,  message2);
    printf("\n");

    while (client) {
        if (client.available()) {
            while (client.available()) {
                char response[128] = {};
                client.read(response, sizeof(response) - 1);
                printf("%s", response);
            }
            client.close();
        }
    }
    printf("\ndone\n");
}

int encodeFormUrl(char *s, char *t) {
    char *head = t;
    for (char c; (c = *s) != 0; s++)
        switch (c) {
            case '\r':
                break;
            case ' ' :
                *t++ = '+';
                break;
            default:
                t += sprintf(t, isalnum(c) ? "%c" : (c == '\n') ? "\r%c" : "%%%02X", c);
        }
    *t = '\0';
    return t - head;
}

void encodeBase64(char ibuf[], int length, char *obuf) {
    const char BASE64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    int i, j;
    for (i = j = 0; j < length; j += 3, i += 4) {
        long a = ibuf[j] << 16 | (j + 1 < length ? ibuf[j + 1] << 8 : 0) | (j + 2 < length ? ibuf[j + 2] : 0);
        for (int k = 3; k >= 0; k--, a >>= 6)
            obuf[i + k] = (j + k - 1) < length ? BASE64[a & 63] : '=';
    }
    obuf[i] = '\0';
}

void encodeBase64(char *ibuf, char *obuf) {
    encodeBase64(ibuf, strlen(ibuf), obuf);
}