POSTメソッドで受け取ったbodyからバイナリデータを取り出し、IPFSノードにアップロードするNode.jsのプログラムのプログラム片。

uploadToIpfs.js

// See https://pandanote.info/?p=8723 for details.
import * as fs from 'fs';
import axios from 'axios';
import FormData from 'form-data';

function getBoundary(header) {
	var tmpct = header['content-type'].split(/;/);
	var boundary = tmpct.filter(function(e) {
		return e.trim().startsWith("boundary=");
	});
	if (boundary.length > 0) {
		return boundary[0].trim().replace("boundary=","");
	}
	return null;
}

function uploadToIpfs(v, req, res) {
	let buffer = [];
	req.setEncoding('binary');
	let length = 0;
	req.on('data', function(chunk) {
		length += chunk.length;
		buffer += chunk;
	});
	req.on('end', async function() {
		console.log(req.headers);
		// console.log(buffer.length);
		var boundary = getBoundary(req.headers);
		if (boundary != null) {
			var partlist = [];
			var attrlist = {};
			// 0: start,
			// 1: in-part(text),
			// 2: in-part(pre-content),
			// 3: in-part(binary)
			var mode = 0;
			var linebuf = [];
			var i = 0;
			while (i < buffer.length) {
				const cp = i > 0?buffer.charCodeAt(i-1) & 0xff: 0;
				const c = buffer.charCodeAt(i) & 0xff;
				if (mode != 3) {
					if (cp == 0x0d && c == 0x0a) {
						var lb = linebuf.trim();
						linebuf = [];
						if (lb == "--"+boundary) {
							mode = 1;
						} else if (mode == 1) {
							if (lb.startsWith("Content-Disposition")) {
								var attrs = lb.replace(/^Content-Disposition:\s+/,"").split(/;/);
								attrs.forEach(attr => {
									var at = attr.trim().split(/=/);
								if (at.length < 2) {
									attrlist[at[0]] = "";
								} else {
									attrlist[at[0]] = at[1].replace(/^\"([^\"]+)\"/,"$1");
								}
								});
							//console.log(attrlist);
							} else if (lb.startsWith("Content-Type")) {
								attrlist["Content-Type"] = lb.replace(/^Content-Type:\s+/,"");
								partlist.push(attrlist);
								attrlist = {};
								mode = 2;
								//console.log(partlist);
							}
						} else if (mode == 2) {
							mode = 3;
							var ccp = 0;
							var cc = 0;
							do {
								i+=2;
								ccp = buffer.length > i-1? buffer.charCodeAt(i-1) & 0xff: 0;
								cc = buffer.length > i? buffer.charCodeAt(i) & 0xff: 0;
								//console.log(ccp+":"+cc);
							} while(ccp == 0x0d && cc == 0x0a);
							i-=2;
						}
					} else {
						linebuf += buffer[i];
					}
				} else {
					var j = buffer.indexOf("--"+boundary,i);
					if (j > i) {
						partlist[partlist.length-1]["content"] = buffer.slice(i,j-2);
						mode = 0;
						linebuf = [];
						//console.log(partlist);
						i = j-1;
						//console.log(partlist[partlist.length-1]["content"].length);
					}
				}
				i++;
			}
			let buf = Buffer.from(partlist[partlist.length-1]["content"],'binary');
			var ipfsform = new FormData();
			ipfsform.append("image",buf);
			axios.post('http://localhost:5001/api/v0/add', ipfsform,
							 { headers: ipfsform.getHeaders() })
				.then(response => {
					res.writeHead(200, {"Content-Type": "text/plain"});
					res.write(JSON.stringify(response.data));
					res.end();
				})
				.catch(error => {
					console.log(error);
					res.writeHead(500, {"Content-Type": "text/plain"});
					res.write(error);
					res.end();					   
				});
		} else {
			// console.log(error);
			res.writeHead(400, {"Content-Type": 'text/html; charset=utf-8'});
			res.write(fs.readFileSync("static/400.html"));
			res.end();
		}
	});
}